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Spring 2016

Diagnostic Radiography VETT-116

QuestionAnswer
effects of radiation- cannot feel pain or effects environmental -sun), medical -Xray imaging, CAT Occupational- Xray techs, vet techs.
Why X-rays are so harmful effects are accumulative over time. Rad is colorless, odorless and painless,
4 effects on living tissue 1. Pass through and cause no damage 2. Produce repairable cell damage as new cells replace old damaged cells. 3. Produce permanent cell damage-not repairable 4.Kill the cell, and eventually kill the tissue
Cells and tissues most sensitive to radiation rapidly dividing cells-organ systems, responsible for growth and reproduction. pregnant women, cancer cells. Bone and lymphatic tissue-cause decrease in white blood reducing immunity and resistant's. Skin -squamous cell carcinoma
Results of overexposure to radiation Somatic or Genetic
Somatic( has some in it) may occur sometime during life time or immediate- cancer cataract or sterility
Genetic ( has gene in it ) enters genes of reproductive cells, alters DNA or gene mutation may cause birth defects
Exposure from the radiation machine 1. primary beam ( use lead line glove and stay out of beam when restraining patient) 2. scatter radiation-Xray travels in a straight line, unless it bounces off another surface. 3. Leakage from the
Exposure from the radiation machine Xray tube when handling, a greater distance from the machine will decrease or eliminate exposure
MPD maximum permissible dose Measuring exposure max dose of radiation an individual may receive during a specific period. the MPD levels are determined by NCRP nation council/committee on radiation protection and measurements-non profit organization of experts
whole body exposure limits ( over 18 years of age ) -5 rem or 0.05 Sieverts (sv)
Tracking exposer- dosimeters 1 device per person,worn by individual when xrays being made only, device should be sent to outside lab for processing and evaluation on a regular basis. tied to SS number
4 types of radiation exposure monitoring devices 1. film badge-rings , wrist bands to clip on. pregnant should wear 2 one at waste high. 2. TLS thermoluminescent dosimeters -calcium or lithium fluoride. 3. OSL-optically stimulated luminescence badges-
4 types of rad exposure monitoring devices 4. Ion chamber-little pocket device, size of pen and provides immediate feed back
maintaining radiation protection gear techs responsible for maintenance -look for cracks, holes, leaks and wear. made of rubber and lead lining. aprons should be hung vertically or laid flat. don't stack stuff on top.
maintaining radiation protection gear gloves should not be folded may cause cracks. inspect regularly. have an inspection chart
Radiation safety remove all unnecessary personnel from room. this prevents unnecessary exposure. rotate staff decreases the amount of Rad to 1-2 people, and cross trains staff.
Chemical restraint procedure may be recommended vet, not necessary for every patient. patient can be supported by sand bags or other cushions adhesive tape, anesthesia. Reduces exposure to more than one staff.
PPE- personal protection equipment 0.25 mm -1 mm lead lining in gloves, apron , thyroid protectors and gloves. Keep any part of body outside primary beam. Do not point beam at anyone. do not aim at wall if someone is on the other side of the wall if walls are not lead line
Collimator a part of X ray machine, used to restrict field size of xray beam. a light will illuminate so you can see size of beam and area it will xray. never hold Xray tube, due top possible tube leakage
Tips on reducing exposure take time to plan have necessary equip and patient is ready. properly position patient the first time, avoid retakes. be patient when doing thorax to cycle through respiration. keep appropriate distance from beam.
Safety Regulations be aware of your laws, regs from State department of health. logs or report. Quality control records, specific safety guidelines. keep log of ALL radiographs with date, patient views and exposure settings
Absorbed dose quantity of energy imparted by ionizing radiations to matter
Dose equivalent quantity obtained by multiplying the absorbed dose in tissue by the quality factor
Dosimeter device used to measure radiation exposure to personnel
Dosimetry various methods used to measure radiation exposure to personnel
Fluoroscopy special radiographic diagnostic method in which a " live view" of the internal anatomy is possible
Genetic damage effects of rad that occur in the genes of reproductive cells
Gray (Gy) unit of absorbed dose imparted by ionizing radiations to matter ( 1 gray = 100 rad)
Hemopoietic anatomic areas where red blood cells are produced
Leukopoietic anatomic areas where white blood cells are produced
Pocket ionization chamber method of dosimetry consisting of a charged ion chamber and electrometer, which can be read immediately to determine the amount of exposure
Primary beam path that the xrays follow as they leave the tube
Secondary radiation commonly called scatter radiation, it is caused by interaction of the primary beam with objects in its path
Sievert (Sv) dose of radiation equivalent to the absorbed dose in tissue ( 1 sv = 100 rem)
Somatic damage damage to the body induced by radiation that becomes manifest within the lifetime of the recipient.
TLD- thermoluminescent dosimeter method of dosimetry consisting of a chamber containing special compounds that become electrically altered by ionizing radiation
Radiaton safety program contains an adequate technique chart, positioning aids, PPE, dosimetry devices, emergency procedure for malfunctioning xray equipment, quality control measurements and tests.
ALARA as low as reasonably achievable
Annual total of exposure whole body up to .05 sv/yearly from occupational and .005 Sv(.5 rem)background exposure. individual organs and tissues 0.5 sv( 50 rem) Occupational, 0.05 Sv (5 rem) background. lens of eye .15 Sv( 1.5 rem) occupational, 0.03 Sv ( 3. rem) background
Background exposure dental xrays, MRIs, CAT
Protection for the patient breeding animals should have their gonads covered when taking xrays to protect the reproduction system
soft Xrays- use a 2.5 aluminum filter to remove soft xrays from the primary beam less penetrating like the bounce off of radiation in a scattering beam. without filters the total skin rad dose for both patient and personnel would increase approx 4 times
Genetic damage this damage might not be detectable until further generations are produced. single massive dose is more extensive than cumulatively equivalent repeated doses
General maintenance of Xray room maintenance of film developing and fixer fluids. cleaning table and machine, free of hair and dirt accumulations also screens and cassettes.
Radiation safety maintenance responsibility includes checking PPE, staff training, using of the PPE, managing, ordering, mailing and maintaining reports for dosimeters badges.
Digital radiography these still involve radiation exposure. They are quickly produced, easily stored and transferred between vet hospitals. quick Dx, clearer and more precise picture.
Computed Tomography (CT)/ Magnetic Resonance Imaging (MRI) this also involves radiation and all principles still apply, safety, maintenance, quality control and patient monitoring
Anode a positively charged electrode
Atom- consists of small particles protons, neutrons and electrons a basic part of matter that consists of a nucleus and a surround cloud of electrons ( shells )
Atomic number the number of protons in an atoms nucleus
Cathode A negatively charged electrode
Electromagnetic radiation : particles and waves a method of transporting energy through space, distinguished by wavelength, frequency and energy
Electromagnetic spectrum electromagnetic radiation grouped according to wavelength and frequency ( infrared, ultraviolet, gamma)
Electron a negatively charged particle that travels around the nucleus
Excitation a process in which an electron is moved to a higher energy level within the atom, moves to another shell closer to the valence shell, or to the valence shell
Fluorescence the ability of a substance to emit visible light
Frequency the number of cycles of the wave that pass a stationary point in a second. higher frequency = higher power of the energy
Gamma Rays electromagnetic radiation emitted from the nucleus of radioactive substances
Infrared Rays electromagnetic radiation, beyond the red end of the visible spectrum characterized by long wavelengths
Ionization a process in which an outer electron is removed from the atom to that the atom is left positively charged. this process takes more energy than excitation
Neutron a neutral particle located in the nucleus of an atom
Photons A bundle of radiant energy ( synonymous with quanta) they have no mass or electrical charge. they consist of pure energy and are transported or carried by the wave
Proton a positively charged particle located in the nucleus of an atom
Quanta a bundle of radiant energy (synonymous with photons )
Radiant energy energy contained in light rays or any other form of radiation
Radiograph a visible photographic record on film produced by Xrays passing through an object
Shell an electrons orbital path and energy level. atoms surround the nucleus
Ultraviolet rays electromagnetic radiation, beyond the violet end of the visible spectrum that is characterized by short wavelengths
Vacuum an area from which all air has been removed
Wavelength the distance between 2 consecutive corresponding points on a wave EX top of 1 hill to the top of the next. the shorter the length higher the frequency and penetrating power the energy has thru space and matter, longer the wavelengths lower the frequency
Xray 1% of the energy from fast moving electrons. the form of electromagnetic radiation similar to visible light but of a shorter wavelength. generated when fast moving electrons (negative particles) collide with any matter. best achieved in an xray tube
Xray beam a number of xrays traveling together through space at a rapid speed or wave. these bundles of energy quanta or photons. have no mass or electrical charge.
Wavelength groups starting with the shortest waves Cosmic. gamma, Xray, ultraviolet( sun), visible. infrared, TV and radar, radio waves
Xray tube when charged particles ( 2 electrodes cathode and anode that are opposite electrical charges ) when they collide the give off a lot of heat. are slowed down or stopped by atoms of a target area, this process occurs in the xray tube to create an xray beam
energy of radiation is proportional to the wavelength meaning xrays that have a shorter wavelength penetrate farther than xrays that have longer wavelengths
7 Physical properties of Xray electromagnetic radiation one and two properties 1. wavelength is variable and is related to the energy of the radiation 2. travel is in a straight line, direction can be altered but the new path is also a straight line
third property 3. with extremely short wavelengh, xrays can penetrate materials that absorb/reflect visible light. gradually absorbed the farther they pass thru an object.
third property amount of absorption depends on the atomic number, the physical density of the object and energy of the xray
fourth property 4. fluorescence (emit visible light) crystalline substances like calcium tungstate or rare earth phosphors florescence( emit light) with the visible spectrum after absorbing electromagnetic radiation of a shorter wavelength
fifth property 5. xrays produce an invisible image on photographic film that can be made visible by processing the film
sixth property 6. xrays have the ability to excite or ionize the atoms and molecules of the substances including gases through which they pass. Excitation is a process in which an electron is moved to a higher energy level withing the atom.
sixth property energy is required to initiate this change. ionization is a process in which an outer electron is removed from the atom so it is left positively charged, this requires more energy than excitation
seventh property 7. xrays cause biologic changes in living tissue. change occurs by direct action of excitation and ionization on important molecules in cells or indirectly as a result of chemical changes occurring near the cells. affected cells may be damaged or killed
William Roentgen- founder of the Xray machine the first written report concerning xrays and their use for medical and surgical diagnosis was make in 1895
radiation waves that kills cells and tissue is the smallest wave and the most dangerous, cosmic, gamma
Radiography vs Xray Xray used instead of radiography its a form of electromagnetic radiation used to produce a visible image. Radiograph refers to the actual photographic record that is produced by the xray passing thru the object so radiography is preferred
key features of an Xray machine a table for positioning, (or hand held for large animals) a control panel to select kilovoltage, milliamperage and time of exposure on a common selector control. must be set correctly for a properly exposed radiograph
mA- the number if electrons produced stands for milliamperage, the dial automatically sets the highest mA station and the fastest time to provide the requested mA , the lower the mA the lower numbers or less electrons. the higher the mA the higher number of the electrons
Milliamperage x time in seconds controls the volume or number of xray photons produced.
Andre M Ampere the A in mA is the scientist credited with the discovery of eclectic currents
3 types of Xray machines portable, mobile and stationary units
Portable xray- should never be hand held can be carried easily from one location to another. weighs from 6.75-20.25 kgs, used on blocks or stands
Common characteristics of a portable xray single focal point ( 1.2mm) stationary anode tube, 1 filament. collimation from lead plate w adjustable field. tube output 90 kVp at 10 mAs. electronic timer from 0.01-10 sec. uses 110v with a 220v adapter. some have 12 Dc current or battery
Mobile unit medium powered, wheels mounted that can move around the hospital, not used for outside hospital. mostly used as fixed units on a designated room. power cord can be in the way
Stationary units the most powerful, the tube can be suspended from the ceiling, the tube can rotate 90 degrees in all directions and has a heavy duty collimator usually 300-500 mAs with exposure times of 1/60 to 1/120 of a second
Fluoroscopy study of moving structures. an image that is continuous in time. involves a direct xray beam through patient into an image intensifier. the intensifier amplifies the xrays coming through the patient reducing the amount of radiation needed
Fluoroscopy for continuous exposure. images can be videotaped for analysis.
uses for fluoroscopy gastrointestinal studies, tracheal studies, myelography and heart and vascular studies
Digital imaging used for computed tomography CT, diagnostic ultrasound, nuclear medicine, magnetic resonance imaging (MRI) digital radiography DR, computed radiography CR and digital fluoroscopy DF, endoscopy
Digital radiography (DR) an xray tube coupled to a specialized detector panel that changes xrays into electrical signals. the analog image is digitized and displayed on computer screen. allows postproduction digital enhancement.
Digital radiography (DR) - uses film operator can alter the image using software, decreases retakes.
Computed radiography CR- doesn't use film instead of film being used CR uses a plate/ all chemical exposure , expense and darkroom time are eliminated because the plate is run through a computer scanner to read and digitize the image. image acquisition is slightly longer with this method
Image quality in CR allows images to see both bone and tissue. the spatial ( 2 adjacent structures) and wide latitude ( range of many shades of grey)
Quantum Mottle is severe underexposure resulting in too few xray photons striking the detector panel or plate leading to grainy images with poor resolution.
Acceleration increase in speed over time
Alloy a mixture of metals
Anode copper with the tungsten targeted area. a positively charged electrode that acts as a target for the electrons from the cathode. Electrons interacting with the anode produce heat and xrays
Cathode a negatively charged electrode that provides a source of electrons, holds the filament the when heated emits electrons
Collimator a restrictive device used to control the size of the primary xray beam
console the control panel of the xray machine
Effective focal spot the area of the focal spot that is visible through the xray tube window and directed toward the xray film. this spot is always smaller than the actual focal spot
filament part of a low energy circuit in the cathode that when heated releases electrons from their orbits
Actual Focal spot the small area of the target which electrons collide on the anode. this spot is always larger than the effective focal spot
Film Records must be recorded like any other record. name of patient, owner address of hospital, date, patient info( breed, age, gender and view) handled so not damaged and loss of film
Film identification - must be permanent on the exposure lead markers on cassette prior to exposure. lead lined tape written with information affixed to cassette prior to exposure. Photo imprinting system. flashed on film after image taken but before processing. R and L markers
window bottom of tube where radiations passes thru to take the image
Focusing cup a recessed area where the filament lies, directing the electrons toward the anode
Glass envelope glass vacuum tube that contains the anode and cathode of the xray tube
Heel effect a decreased of xray intensity on the anode side of the xray beam caused by the anode target angle.
Kilovoltage kV the amount of electrical energy being applied to the anode and cathode to accelerate the electrons from the cathode to the anode ( 1 kV-1000 volts (V) )
Kilovoltage peak kVp peak or maxi energy at that kilovoltage setting, higher the Kilos faster eletrons are accelerated. this acceleration increases the energy of the xrays produced at the electron collision with the anode target, shorter wavelength more penetrating power
Line focus principle the effect of making the actual focal spot size appear small when viewed from the position of the film because of the angle of the target to the electron stream
Milliamperage mA amount of electrical energy being applied to the filament, mA describes the number of xrays produced during exposure
Molybdenum a metal commonly used on focusing cups because if its high melting point and poor conduction of heat
Penumbra or halo effect partial out shadow of an object being imaged by illumination
Rotating anode an anode that turns on an axis to increase xray production while dissipating heat
Stationary anode a nonmoving anode, usually found in dental and small portable radiographic units
Target on the anode where the electrons hit
Tungsten a common metal used in a filament of a cathode
Xray tube a mechanism consisting of an anode and cathode in a vacuum that produces a controlled xray beam. is source of elections. method of accelerating electrons, obstacle free path of high speed electrons, a target in which electrons can
Xray tube interact, releasing energy in the form of xrays, an envelope to provide a vacuum environment eliminating the air from the electron stream and preventing rapid oxidation of the elements
Exposure button on the control panel or attached by a length of cable. the button s/b position at least 2 meters form the tube housing .
control panel components voltage compensator, kilovoltage selector, on/off switch, milliamperage selector, timer, exposure button, warning light
what is required on a label of a radiograph name of patient, name of owner, name and address of hospital, date, patient information
what is the electrical components of the xray machine transformer, generator, line voltage compensator, timer and rectifier
More xrays leave the xray tube on the anode side
High kilovoltage (kVp) and low milliamperage-second(mAs) are 2 electrical circuits, the kilo circuit controls the electrical potential between the anode and cathode. that controls the speed of electron acceleration and the energy level or penetrability of the resulting xray beam. the milli circuit
kVp's and mAs controls the electrical potential across the filament and affects the volume of electrons created and thus the number or volume of xrays created.
Stationary anode stationary anode target area is small tungsten block 3.18 mm thick in copper. good for extremities of horses and dogs.. but limited for abdomen and thorax because it cannot produce enough powerful xray beam to penetrate thicker
Stationary anode body parts, also limited in its ability to produce short xray exposure of efficient strength for chest radiograph to eliminate respiratory motion artifact
Rotating anode rotation anodes produce higher quality images. rotating tubes can use much higher tube currents, shorter exposure times and focal spots as small as 0.1mm because electrons deposit their energy over a larger target region as the anode
Rotating anode rotates, these tubes must dissipate enormous amounts of heat. rotation machines have a 2 step exposure switch. the 1st step starts the anode rotating, the 2nd switch activates the high voltage circuit, resulting in xray production.
Rotating anode the anode is angled for 2 reasons, on e directs the xray beam vertically to exit the tube window and two it creates a smaller more compact effective focal spot to create better resolution and produce a higher quality radiograph
patient placement always place the thickest part of the patient on the cathode side of the xray tube, a more uniformed density can be obtained on the radiograph
Tube rating chart provided by all manufacturer's of xray tubes. it provides important information on the maximum safe exposure time that can be used with specific milliamperage and kilovoltage settings. longer than designated exposure times are used ,
Tube rating chart tube damage may occur. the size of the anode focal spot determines the rating of the tube because size controls the amount of energy it can absorb and convert into xrays and heat
physics of Xray production xrays are produced when all energy packed in extremely rapidly moving electrons comes to an abrupt stop on encountering the target in the xray tube. 99% of the energy dissipates in the target and lost as heat. 1% is converted into xray energy.
physics of Xray production 2 events occur when electrons approach the atoms of the target. 1st electrons miss the atoms and their orbital electrons and go thru the entire target and absorbed by the
physics of Xray production backing material of the target or lead shielding of the xray tube. 2nd incoming electrons may interact with the electron cloud of the atoms in the target material and produce xrays by transferring their energy to these atoms. both events produce xray
physics of Xray production photons most of which are produced by slowing of the electrons as they are absorbed into the target. the faster electrons travel greater is their energy and therefore the greater is the energy, as well as the penetrating power of the resulting xray beam
Scatter radiation -are the main source of radiation exposure for vet techs when an xray passes through a patient,the beam becomes attenuated or its energy is decreased gradually. scatter radiations are lower energy xray photons that have undergone a change in direction after interacting with structures in the patients body.
Scatter radiation scatter is a concern because it decreases film quality and increases radiation exposure for personnel involved in taking the xray. most scatter rad contribute to the overall film
Scatter radiation blackness or radiographic density, but does not contribute to the useful image. this results in reduced subject contrast. scatter rad are directly increased with the increases in these
Scatter radiation 3 factors. kilovoltage, thickness of the part being x-rayed and size of the field. to reduce exposure the use of beam limiting devices, correct kilos settings, compression radiography and grids are used
properly exposed radiographs must have the kilovoltage, milliamperage and time of exposure set correctly to have a properly exposed radiograph
Heel effects when an xray leaves the tube and has an uneven xray photon distribution, is related to the angle of the target areas and to absorption by the anode and target material. as a result the beam is more intense at the side of the
Heel effects cathode than in the center beam or on the anode side. when x-raying parts of uneven thickness, a problem in thoracic and abdominals or deep chested dogs, by placing the thick part toward the cathode side makes uniform density
Quality of an xray beam is determined by its penetrating power. shorter wavelength radiation has increased penetrating power and is said to have increased penetrating ability
Quantity or intensity of an xray beam is defined as the amount of energy flowing per second through a unit area perpendicular to the direction of the beam. Or is 3.20
Exposure time the period in which the xrays are permitted to leave the tube. it is measured in fractions of seconds. Time part is how long the window is open for electrons to be produced. like shutter speed on a camera
Milliamperage-seconds mAs is the quantity of xrays required for a given exposure. is the product of mA x time( in seconds) x mAs.
example of mAs calculations 20 mA x1/2 sec=10 mAs. how? 20x1/2=20/2=10, OR 100 mA x 1/10 sec=10 mAs How? 100x1/10 = 100/10=10. 100mA x 1/20 s-5mAs, 300mA x 1/60=5mAs. 300mA x 1/20= 15mAs. 200mA x 1/10s=20 mAs
Higher kVp means lower mAs means shorter exposure time.
Distance in xrays- SID source image distance the distance between source of xray(focal spot of tube) and the image receptor ( cassette or film) also affects the intensity of the image produced as the SID is decreased the
Distance in xrays intensity of the xray is increased, if the SID increases the intensity of the xray decreases
Inverse square law- if FFD is doubled the mAs must increase 4 x to maintain density increasing the distance from the radiation source reduces the intensity of the beam. radiographic density is affected by a change in distance. when the SID is changed the total amount of xrays must be increased or decreased in order to
Inverse square law make a comparable exposure using the new distance. this can be done by changing the mAs which governs the rate in which the xray tube produces xradiation.
calculating a different distance by adjustments of the mAs old mAs ( new sid)2/( old sid)2 = new mAs
When the SID is changed image detail is changed. as any SID is decreased image sharpness is decreased. the SID is an important factor. whenever possible , the SID should be kept constant. the most common SID in vet practice is ranges from 36 to 48
When the SID is changed inches ( 80-110 cm) usually noted on the tube stand or housing verify the SID before every radiograph because of the effect of the SID on radiographic film density
The most common artifact in radiology is motion. screws the image every time
Radiographic density or blackness of a film. tissue will absorb xrays different like ,fat , water or muscle and bone air fully inflated is better, fat less dense than muscle.( adjust settings appropriately ) water or muscle, less dense than bone but more dense than fat.,
Radiographic density bone absorbs more xray than muscle. ( appears more white) Metal is most dense screw wires plates, or something swallowed. less dense appears black more dense appears white
Contrast levels of shades in the black, whites and greys. differences in density between various areas and structures. may be altered using the kVp. film fogging may decease density, caused by low grade lights , heat , scatter rad or bad techniques.
Exposure factors time of exposure, mA and kVp, time and mA makes mAs
Milliamperage setting controls the quantity of electrons, will increase heat on filament and number of xrays produced. density will increase also. decrease mAs will decease density and film will be lighter
Time Measured in fractions of seconds. controls how long the electron circuit is allowed to flow from cathode to anode. use the shortest amount of time possible to decrease movement, blurry. make sure exposure time allowed for contact with the film
mAs- milliamperage seconds has an impact on the quantity of xray and also the density of the radiograph. higher mA the shorter time used reduces blur and motion
kVp- kilovoltage peak higher kVp the greater the scale of contrast. higher kVp perpetrates through dense tissue/organs. increased kVp increases scatter rad
Distance 2 distance that may alter images. focal film distance (FFD) distance from the target in the xray tube to the film. usually kept at a constant unless film is moved. Source image distance (SID) or object direct distance is the distance from
Distance the object ( patient ) to film. closer patient to film less likely distorted. closer gives a clearer picture. patent as parallel and close is best.
Grid is used to control scatter radiation before it reaches the cassette. measures greater than 9 cm. placed between patient and film. series of linear or parallel lead strips will help absorb scatter rad. grid can be placed on the cassette or
Grid built into cassette, directly under xray table surface in bucky tray or between patient and film.
types of grid patterns used linear/parallel , linear focused ( in a row), or criss-cross.( 2 separate layers superimposed on each other in different directions like a checker board, used for high levels of rad. as it absorbs scatter rad from all different
Grid ratio sized by height of lead strips and distance between lead strips. grid with 15:1 blocks out more radiation than 5:1 grid.
diagnostic quality radiograph 1. measure area to be radiographed 2. set appropriate kVp and mAs settings. 3. check FFD 4. create exposure 5. process film 6. evaluate for diagnostic quality
In most states, an employee who is terminated for willful violation of safety rules will likely be denied: Unemployment benefits
When positioning an uncooperative patient for a radiograph, it is acceptable to expose your hands to the primary x-ray beam. false
Which is NOT one of the 3 methods of radiation protection? patient positioning
digital imaging and communications in medicine DICOM standard is a universal ditital image format. images produced form equipment using DICOM standard can communicate another vendors software. this functionality enables image storage, query, retrieval, display and manipulation. also store US-ultrasound, MRI, CT,
DICOM radiography, SC or secondary capture like film scanner. a service class provider(SCP) or service calls users (SCUs) allow the DICOM to work.
Picture archival computing PACs computer system used to move images around to different computer work stations within a single or multiple hospitals. and also a method of storing imaging data permanently.
benefits of PACs 1. they eliminate the need to generate and store film hard copies.2. communication to other vets for info dissemination is improved 3. tracking down lost films is not a problem 4. multiple users can view the images at the same time.
disadvantages of PACs when system goes down, blocked or loss of connectivity there is decreased productivity, data can be lost, users must have excellent knowledge of system.
Radiology Information systems RIS software programs that allow all patient data to be made available and coupled with digital imaging data. the data input is coordinated with all other hospital forms and records, like patient id and details are entered into the digital
RIS file and automatically transferred to radiology forms. reduce redundant data entry.
Teleradiology allows transmission of digital data across the internet from private practices to referral centers around the world. specialists can receive images instantly interpret then and quickly send back a written report. no mailing necessary
Exposure factors factors that must be selected include time of exposure, mA and kV, focal film distance, type of intensifying screen, type of xray film and tabletop vs grid technique.
Exposure Milliamperage - to double density double mAs, to halve density halve mAs this controls the quantity of electrons boiled off the filament in the xray tube, its a quantity factor because it controls the quantity of xrays that will be produced at the target area. most operate at a setting of 50-300 mA.
Exposure Milliamperage larger units may have a current flow up to 2000 mA. adjustments of mA setting control allow control of the quantity of xrays produced, increased mA density or film blackness increases, a reduction of mA decreases density or a lighter film results
Exposure time- affects quantity of xray and density of image is the time in fractions of seconds during with the anode is positively charged. the longer the exposure time the greater the number of electrons that flow from the cathode to the anode.. the greater number of xray photons are produced.
Exposure time Because both exposure time and mA affect the number of photons created you want the shortest exposure time possible to decrease patient motion blur always use the highest mA setting and shorter exposure time.
exposure Kilovoltage kV-increases density is the quality factor that regulate the energy of the xray beam. the setting regulates the voltage differential applied between the anode and cathode in the tube. high voltage the faster the electrons are accelerated and the greater the energy of the
exposure Kilovoltage kV increases density beam.the greater the energy, the greater amount of patient tissue that an be penetrated. increasing the kA will also increase density/film blackness because of the increased photons passing through the patient most common setting is 40k-150k V ( 40-150 kV
kV and the scale of contrast refers to the number of shades of grey that can be seen. if not contrast existed all radiographs would be opaque. low kVp setting produces higher contrast image -more lack and white in appearance with few grays. Use of high kVps
kV and the scale of contrast results in a darker image which show little difference in opacity between bone , soft tissue and fat. kVp must be set high enough to penetrate the patient but not so high as to decrease contrast,
increasing radiographic density or film blackness by increasing the energy level of the photons (kVp) or the total number of photons (mAs)
Focal film distance FFD- standard is 40 cm is the distance between the focal spot on the anode in the tube and the xray detector. this factor is normally kept constant from one exposure to the next the norm is 90-105 cm(36-42 in) for small animals. 70-85 cm (28-34 in) for large animals
Focal film distance keeping the distance constant because it has a significant influence on exposure factors. an increase in distance decreases the number of xrays reaching the film. this is not
Focal film distance a linear relationship. if you double the focal film distance the number of xrays reaching the film will be reduced by a factor of 4.
Inverse square law- if FFD is doubled, must increase 4x's the intensity of the xray beam at a given point is inversely proportional to the square of the distance from the xray source . So, if you double the film distance from xray source, you will decrease the beam intensity to 1/4 of the
Inverse square law original strength, small changes in focal distance can result in big changes in density
Radiographic film quality utmost important to produce a radiograph of excellent quality to arrive at a diagnosis. a film of good diagnostic quality should provide excellent detail, correct scale of contrast and optimal density
radiographic detail refers to the degree of sharpness that defines the edge of an anatomic structure. represents the best possible reproduction of an organ, detail is influenced by every possible factor , geometry and motion factors are more influential than others.
radiographic detail the FFD or focal film distance or SID source image distance is important factor of image lose. if the spot is too close to the part xray'd magnification and lack of distinction will be noted at the margins of the structures.
radiographic detail therefore its important to keep FFD as long as possible without reducing beam intensity.
Object film distance OFD should be kept as short as possible to prevent image distortion ( penumbra effect )due to magnification, this is why the goal is to have the object being examined as close the xray detector as possible
Movement a factor that influences detail can be due to respiration, intestinal or patient movement. sedation is necessary to prevent unsharpness due to patient movement and mA settings are adjusted to prevent blurring due to breathing or bowel movements, thorax xrays need at
Movement a factor that influences detail least 1/30 sec to ideally 1/120 exposure time to prevent blurring
Size of focal spot influences detail the larger the spot the poorer the detail, because most equipment has a rather large focal spot of 0.8 mm or greater. loss of detail may be significant. place the part to be xrayed as close as possible to the film if too far the
Size of focal spot influences detail magnification and distortion will loss detail.
Other factors that affect detail - poor processing causes more ruined film than all other factors combined poor film screen contact, over and under exposure often result from improper technique chart or carelessness. scatter rad. light leakage, rapid high temp processing techniques
Radiographic contrast refers to the density or opacity difference between 2 areas on a radiograph. High contrast - fewer shades of grey also very black and white. high contrast is ideal for spine and extremity film
latitude refers to the range of different opacities on the radiograph, Long latitude has a much larger number of shades of gray and are good for thoracic film. but the difference or contrast between shades is small.
Greatest influence on contrast is kV the higher the kV the greater the latitude therefore the greater the number of shades of black gray and white.( lower contrast) Absorption of beam at high kV is more uniform among the various tissues in the body, resulting in
Greatest influence on contrast is kV less contrast. therefore thoracic examination, a high kV is recommended to produce a higher contrast image.
magnification a technique that is rarely used in vet practice but popular in teaching hospitals, based on principle that a larger image of anatomic structure can be obtained if the distance between the object and the film is increased. the result is twice as
magnification large as the actual structure , for diagnostic film its necessary to have a small focal spot of 0.3 mm or smaller
Technical errors and artifacts caused by technician error, poor film processing. important to make sure film processors are clean at all times, roller assembly cleaned once a week. serviced regularly, fresh fixer and solution is provided as needed
increased film density error mA or kV setting too high, FFD is too short, wrong measurement of anatomic part. equip malfunction, speed of intensifying screen too fast.
decreased film density error mA or kV setting to low, FFD is too long, wrong measurement of anatomic part, speed of intensifying screen too slow
Black marks or artifacts error film scratches, crescent mark from rough handling, static electricity ( lineal dots or tree patterns). top of film is black do to exposure to light while in box, defective cassette that does not close properly, exposing margin of film to ligh
White marks of artifacts error dirt or debris between film and screen, defect or crack in screen, contrast medium on tabletop, skin or cassette
Grey film error film exposed to radiation ( scatter, secondary or direct) lack of grid for exam of a thick part, outdated film, film stored in hot or humid place
Distorted or blurred radiograph error motion of patient, cassette or machine, OFD too great causing magnification and distortion. poor film screen contact, poor centering of primary beam
Linear Artifact error gridlines, grid out of focus, primary bean mot centered, grid upside down, grid damaged, causing distorted gridline
Miscellaneous artifact error cone cut, causing underexposed margins, target damage, resulting in inconsistent film density require tube replacements, double exposure, blank film: faulty equipment, nonexposed film processed
Four 4 exposure factors control density contrast detail mA, kVp, focal film distance FFD and source image distance SID, object film distance OFD. changing one factor usually requires adjustments in another factor to maintain the same density
Santes rule : 2 x thickness +40= kVp when thickness is less than 10cm. higher cm means the grid factor must be in place and the formula is now 2 x thickness + 40(SID) + X( grid factor) =kVp
Santes rule : is a formula used to estimate kV in relation to area of thickness. this can be used in combination with the measurements of the patients thickness of the area to be imaged and the FFD. measured with calipers in centimeters.
Effects of exposure mAs, low #=image to light( under exposed) too High-=image too dark( overexposed) kVps= low high contrast, but with soft tissue can be lost. kVps too high-low contrast( uniform grey), FFD- low=image overexposed, high=image underexposed,
Effects of exposure OFD-Low=cannot be too low, object can only be so close to film, high= magnification and blurring of edges and structures
When radiographing skeletal, or bone, structures, use: lower kVp, higher mAs
which body part has the shortest scale of contrast femur
When completing a radiographic exposure, if you double the mAs, you will double the radiographic density. true or it increases the kVp by 20%, to halve radiographic density decrease kVp by 16%
image formation with film screen systems xray beams penetrates a body system and reaches an xray film, a latent image is produced that will be revealed when the film is processed chemically. several factors involved.
Xray cassette or film holders. 2 types nonscreen or nonrigid and rigid intensifying screen,fronts can be made of polycarbonate ( bakelite) aluminum , magnesium and carbon fiber. Can be color coated on the edge to identify the screen type inside.
Nonscreen or Nonrigid cassette is a direct exposure cassette which the film is placed in a cardboard cassette or plastic film holder. must be light proof,. is used for greater detail like intraoral occlusal of nasal cavity and dental arches. Disadvantage is it requires
Nonscreen or Nonrigid cassette sedation or anesthetic and longer exposure time, 26 x more than normal exposure time. no personnel are required for restraint in the room
Nonrigid these should be used only when the animals is under anesthetic or sedation motion. no personnel required to restrain or be in the room
Rigid cassette intensifying screen more conventional image intensifying screen. placed in a rigid cassette with high quality hinges to ensure uniform contact between the xray film and the intensifying screen and to prevent light leakage that could fog or darken film.
Rigid cassette intensifying screen they have solid fronts of plastic or light metal or carbon fiber. carbon fiber can reduce quantity of xrays needed by 20%. cassette back made of steel and hold moderate weight.
intensifying screens- high level of xray absorption, high xray to light conversion and little or no afterglow are smooth shiny white inner surface, made of layers of tiny crystals bonded together on a plastic support and covered with a protective coating. crystals are fluoresce, or emit light after exposure to xrays. screens are placed into the inner
intensifying screens surfaces of the cassette and the film is sandwiched between. fluorescence decreases the amount of radiation needed to produce a film of diagnostic density.
intensifying screens uses much lower mAs which decreases loss of detail to motion, patient exposure, helps prolong life of xray tube. screens are mounted in pairs
Components of intensifying screens 1. Backing of cardboard or plastic ( Mylar ) 2. reflection layers like titanium dioxide that reflect light from active layer back toward film. 3. active layer of light emitting phosphor, like calcium tungstate or rare earth material produces
Components of intensifying screens florescence, exposing the film after absorption of rays. 4.a plastic coating that reduces static electricity and provides protective covering that can be cleaned
Maintenance of intensifying screens must be cleaned on a regular basis-monthly or when artifacts are noted. use product recommended by manufacturer. if product is not available use 70% alcohol solution. screen must be completely dry before inserting film
cross section of an intensifying screen- whats inside the cassette From the cassette front padding, support layer, intensifying screen, phosphor layer, double coated film( inside is emulsion, support and another emulsion layer), phosphor layer, support layer , back padding, lead foil and cassette back
Screen speed- is the ability to convert absorbed xray energy into visible light refers to the amount of radiation required by that screen to produce a film. a fast screen requires less radiation than regular, medium or par screen to produce same degree of blackness on radiograph.
fast film screen- the faster the poorer detail or resolution. require less radiation than regular, medium or par screens to produce the same degree of blackness. they have thicker phosphor layer and larger crystals to increase xray absorption and light production
slow film screen- better detail have smaller crystals and are less efficient at light conversion but produce greater detail and resolution than fast screen, requires greater exposure by xray. is less grainy and greater definition, greater latitude
Fine screen or detail screen require 4 times amount of radiation required by a medium or par screen. fine screens are best for obtaining radiographs of birds or small exotic animals.
Regular screens more expensive are intermediate in speed between par or medium and fast screens
Rare earth screens are more efficient because they absorb more xray photons per crystal and produce more light per absorbed photon. need special xray film to produce optimal film.
Advantage of rare earth screens reduce exposure time/ reduced motion artifacts / decreased tube voltage, resulting in improved contrasts / decreased tube current, which prolongs the love of the tube / reduced production of heat in the xray tube/ reduced patient/technician radiation dose
relative speed of calcium tungstate and Rare earth screens fine detail Calcium ASA film speed 30. par calcium 100, fine detail rare earth 150, regular calcium 200, fast calcium 250, medium rare earth 300, regular rare earth 400, fast rare earth 600
Advantages of Rare Earth screens- good for large animals due to speed they require fewer rays to produce great radiographs, lower exposures means lower radiation doses to patient and tech, fewer retakes due to patient motion and longer xray tube life
Disadvantage of Rare earth screens is cost, much greater than calcium tungsten screens. screens last 10-12 years.
Screen craze is the white speckled pattern most notably in the black areas on the film
Xray films are prepared from suspension of light and xray sensitive granules embedded in a gelatin emulsion usually silver bromide crystals of different sizes. the gelatin mix is protected by a thin covering called T coat.
Small crystal containing film, slower film take images of great detail but longer exposure time than large crystals
Large crystal containing film, faster film is in faster films but results in loss of detail, but is compensated by shorter exposure times. because of the shorter time faster films provide betting image detail due to few motion artifacts
Xray films 2 categories screen film and nonscreen film. be sure that the xray film you are using is maximally sensitive to the spectrum of light that the screens are emitting
screen film- has silver halides has is sensitive primarily to wavelengths of light emitted from intensifying screens. less sensitive to ionizing radiation, but sensitive to visible/flourescent light. less exposure time due to sensitivity of fluorescence emitted by intensifying screens.
screen film film should match in sensitivity to the light of the spectrum of the screen usually blue sensitive, highly responsive to ultraviolet violet and blue spectrum
nonscreen film - direct exposure film -this type is exposed by xrays only are designed for direct exposer to xrays and are relatively insensitive to visible light from screens. provides superb detail and are good for intraoral nasal cavity, dental studies. and bony extremities. disadvantage-needing longer
nonscreen film- this type is exposed by xrays only exposure times. patients s/b sedated and no personnel should be in the room.
Afterglow the tendency of a luminescent compound to continue to give off light after xray has stopped
Base a transparent flexible polyester support layer of radiographic film, tinted blue each side has a adhesive layer
cassette a lightproof encasement designed to hold xray film and intensifying screens in close contact
Emulsion a layer of radiographic film made of gelatin containing suspended silver halide crystals suspended and dispersed evenly throughout the layer. Gelatin provides reasonable permanence and allows rapid processing ,its easily penetrated by developing solution
Film latitude the exposure range of a film that will produce acceptable densities. Wide latitude considered the forgiving film. Narrow latitude or high contrast requires less change in exposure factors or processing to alter density
Fluoroscopy a special radiographic diagnostic method by which a "live view" of the internal anatomy is possible
Intensifying screens sheets of luminescent phosphor crystals bound together and mounted on a clapboard or plastic base
Latent Image an invisible image on the xray film after it is exposed to ionizing radiation or light before processing
Nonscreen film film that is more sensitive to ionizing radiation than to fluorescent light
Quantum Mottle an artifact of faster screens that results in density variation due to random spatial distribution of the phosphor crystals within the screen
Reflective layer a layer of an intensifying screen that reflects the light from the phosphor layer toward the film
Screen film film with silver crystals that is more sensitive to fluorescent light emitted from intensifying screens than to ionizing radiation
Silver Halide a compound of silver and bromine, chlorine or iodine, all of which are in the halogen group of elements. looks like sand under a microscope, suspended in gelatin. has a protective layer that protects it.
Supercoat a clear protective layer on radiographic film. decreases the possibility of damaged to the fragile emulsion
Processing film it is process to convert the latent image into a visable image. more than 95% of the exposure recorded on the film is due to the light emitted from the intensifying screens. Only 5% of the exposure of the film results from the ionization of xrays
Film composition number of layers. the transparent polyester base provides flexible support with a thin adhesive subcoating on each side. adhesive serves to bind the next layer, the emulsion to the base.
Film speed manufactured with various speed though the use of different sized silver halide crystals. speeds determined from exposures required to produce an image with adequate density.
Fast film has larger silver halide crystals, requires less exposure by xray or fluorescent light from intense screens. produces a grainer image /lacks definition has less latitude in exposure factors and processing
Medium film speed ( standard or par speed ) most widely used by vets, represents a compromise between fine grain and speed, has a medium latitude in exposure factors
Film Care cassettes stored so the film is vertical. if horizontal the emulsion may blend causing block xray from pressure then is useless. temps should be cool 10-15 C (50-60F )low relative humidity( 40-60%) not stored near any source of ionizing radiation or
Film Care where vapors from formalin, hydrogen peroxide or ammonia can reach it. it causes fogging or hazing. keep eye on expiration dates.
Key Points Approximately 95% of the exposure recorded on a film is due to the light emitted from the intensifying screens. Only 5% of the exposure of the film results from the ionization of x-rays.
Key Points A cassette must maintain close contact between the intensifying screens and the film. • The primary function of the intensifying screen is to reduce the amount of radiation exposure required to produce a diagnostic radiograph.
Key Points Faster screen speeds require a small exposure and produce less detail; slow screens require a larger exposure and produce greater detail. • Screens must be cleaned regularly. Dirt and hair on the screen can cause radiographic artifacts
Key Points and lead to wrong diagnoses. X-ray film is manufactured with various speeds and latitude.
Dark Room for film processing- dry side cassettes loaded, unloaded. wet side chemicals are 1. keep it clean 2. organized dry and wet side 3. must be light proof-can contribute to film fogging, celling tiles might be source of light leak 4. safelight ( light will not expose or damage film) indirect light is pointed to ceiling
Film process- 5 basic steps 1. developing 2. rinsing ( stop bath) 3. fixing 4. washing 5. drying
Developing chemicals that convert latent image( silver halide) to visible image. use correct time and temperature. developing agents- turns silver to black halides. accelerators-increases activity of the developer. emulsion swells and softens to absorb
Developing more water. preservatives- only changed at intervals ( 3 months) prevents solution from rapid oxidization and prevent staining. Restrainers-protect unexposed silver crystals. Hardener- stops excessive swelling in emulsion.
Rinse bath stop the developing process, rinse any remaining developer from film. or else is will continue developing and have dark film. prevents contamination of the fixer. stop bath-
Rinse bath chemical solution like acidic acid. in automatic process a rinse bath may not be needed
Fixer 2 purposes1. removes any unchanged silver halide crystals 2. hardens the gelatin coating. fixers contain clearing agents or fixing agents to dissolve and remove unexposed crystals from emulsion also changes film from milky white or opacity
Fixer to clear film also contains preservatives to prevent decomposition of the fixing agent while being used. also hardeners part of solution that hardens the film and prevents
Fixer emulsion from swelling also speeds up drying time. Acidifiers neutralize developer that might be carried over to the fixer. Buffers keep the pH balance acidic. solvent-water
Fixer works with fixing agent to remove or dissolve any other ingredients that need to be removed before drying
Wash bath removes processing chemicals from the film, washes film in circulating fresh water, rinse time for 20-30 minutes with periodic agitation. or circulation water
Maintaining processing fluids changed every 3 months or what manufacturer states. Temps should be constant, warmer fluid faster emulsions swell. if its too cool the fluids will not penetrate the emulsions and will take more time. 68F is the norm temp.
Maintaining processing fluids Levels may decrease in volume and strength, adding replenishes. Watch for biologic growth( fungi) tanks should be cleaned with 1% bleach solution, if not clean it could cause artifacts on the film
manual hand processing develop a routine- layout a dark room should be left to right. tank should be set as used. check chemicals with a thermometer ( 68 F), levels checked and stirred , don't use same stirrer to stir other tanks. remove jewelry before
manual hand processing development. put film on hanger and put in developer, agitate a little to remove air bubbles. set timer, reload empty cassette, 5 minutes in developer, place in rinse bath for 30 sec, submerge in fixer, agitate to remove air bubbles. take
manual hand processing about 10 minutes. place in wash tank for rinse time of 20-30 minutes. hung to dry.
Automatic processing involves same principles as manual. advantages-standardized steps and processes. develop quickly and dry time is shortened. minimizes user error. chemicals kept at 95 F for faster processing. emulsion on film for automatic is
Automatic processing harder, to prevent scratches or damage with rollers
Labeling radiograph must have the name and address of the hospital or clinic, date and patient ID ( name age sex and breed) and owner of patient, can be done with a lead marker. must collimate to leave room for marker. lead impregnated tape is easier and cheaper
Labeling radiograph Photo imprinting- imprinting of basic information so it can be placed on film during processing set between film and light source.
radiograph filing system placed in a suitable holder, must be completely dry, labeled appropriately on sleeve, 14x17 in file envelope. file in logical manner
15% rule for kVp If the radiograph is too DARK, DECREASE the kVp by 15%, if the radiograph is too LIGHT, INCREASE the kVp by 15%
15% rule for kVp once you are close to a properly exposed radiograph, use the 15% rule to keep increasing and decreasing the kVp in 5% increments until exposure is right. once the best film is selected, you can begin to formulate your technique charts
Formulating a technique chart start with factors that produce the diagnostic film. then subtract (-)2 kVp for each centimeter decrease from the original measurement . Add 2 kVp to each centimeter increased from the original measurement up to 80 kVp.
Formulating a technique chart Add 3 kVp for each centimeter increase when the kVp is above 80 until you get to 100 kVp. Add 4 kVp for each centimeter increase when the kVp is above 100 kVp until you reach your maximum of 125 kVp
Using a grid in technique charting scatter radiation is increased with increased thickness of a part being xrayed, it is recommended that a grid be used for thicknesses greater than 10 cm. if you are creating a chart for less than 10 cm, a grid doesn't figure into your technique chart
Technique charts are developed for a specific focal film distance, film, cassette screen and development process. if you change any one of these factors within your practice, the technique chart will need to be updated
Santes rule 2 x thickness +40(SID)= kVp when thickness is less than 10cm. higher cm means the grid factor must be in place and the formula is now 2 x thickness + 40(SID) + 8( grid factor) =kVp
Santes rule is a formula used to estimate kV in relation to area of thickness. this can be used in combination with the measurements of the patients thickness of the area to be imaged and the FFD. measured with calipers in centimeters.
Modifying factors under certain circumstances, exposure time will need to change from value indicated by a standard mAs chart. there are the factor and adjustments for common variations
factor- emaciated animals halve mAs
factor- juveniles halve mAs
Facto-r grid not used halve mAs ( depends on grid ratio)
Factor- barium study increase mAs by 50-100%
Factor- pleural effusion increase mAs by 50-100%
Factor- ascites increase mAs by 50-100 %
Factor- Obesity double mAs
Factor- plaster casts double mAs
Factors affecting technique charts speed of screens, age of screens, speed of film, SID ( source image distance), amount of beam filtration, temperature and time of film processing, type of grid
Chats may include screen and nonscreen, grid and non grid, various film screen combinations, species specific, anatomy specific
Exposure too dark decrease mAs by 30-50 % or kVp 10-15%
exposure too light increase mAs by 30-50 % or kVp 10-15%
Test patient for radiograph cooperative adult dog, moderate size and muscling, average weight ( 50lbs) clean hair coat that is medium to short length
Reasons for chart failure the reason may be some of the factors of chemistry, chart, equipment, personnel , other
Chemistry- chart failure aged chemicals, incorrect processing temperature, changed processing time
Chart failure- chart failure failure to extrapolate correctly, inappropriate selection of trial exposure factors
Equipment failure- chart failure unmatched xray film and intensifying screens, faulty exposure timer, variation in line voltage, non-linear kVp.mAs machine settings
Personnel failure-chart failure inconsistent measuring method, sight developing instead of time and temp method
Other reason for chart failure film fog ( faulty safelight or light intrusion)
unexposed film will be clear
Proper positioning of a patient is essential if diagnostic radiographs are to be obtained.. 2 views at right angles are necessary to obtain a proper study. exceptions include, thoracic and spinal examinations in
Proper positioning of a patient horses and examinations in traumatized or debilitated animals when only later views can be taken without causing undue stress.
Proper positioning of a patient important to center the beam on the lesion itself when known. important in orthopedics. EX fracture healing may look different when the beam is centered over the fracture line as opposed to a short distance away. ( keep it close) .
Proper positioning of a patient Use an xray film large enough to cover whole system being examined. May be necessary to use 2 films for abdomen. 1 cranial and 1caudal, also taken at lower kVp setting.
Restraints to achieve proper positioning for proper film taking and radiation safety. some are chemical or manual
Mechanical restraints in many forms. like a muzzle,( has a calming effect) sand bags, sponges, foam or wood blocks and wedges rope, tape, gauze, compression bands. must take picture rapidly because the patient will not hold still for long
Chemical restraints tranquilizer, analgesics or anesthetics. contribute greatly to progress made in radiology by allowing positioning a that otherwise would be impossible. complete exam of skull s/n be done without anesthesia. most spinal review's also.
Chemical restraints Tranquilizers are good for frightened or aggressive dogs and cats or large animals. it takes time and practice to produce a diagnostic radiograph, most organs can be xrayed with proper techniques, equipment and accessory devices.
Ultrasonography is an essential diagnostic tool in vet practice. its portable, does not require use of ionizing radiation and is noninvasive, well tolerated by patients and accepted by clients. has a long learning curve, image quality and
Ultrasonography interpretation are only as good as the skills of the person doing the exam
Ultrasonography basics sound is a mechanical pressure wave made up of a series of compressions and rarefactions transmitted through a medium. sound waves are characterized by wavelength or distance between compression, frequency in cycles per
Ultrasonography basics second and velocity or speed of transmission. characteristics are integrated by the following formula Velocity = wavelength x frequency
Speed of sound in a body is 1540m/sec as the frequency of sound increases, the wavelength decreases, shorter sound waves produce increased image resolution but decreases patient penetration. frequencies used in vet practice generally range from 2.5 to 12 megahertz( MHz)
Hertz ( Hz) is 1 cycle per second ,. typical ultrasound frequencies range from 2.5 million to 12 million cycles per second. audible sound ranges from 20 to 20,000 Hz.
Real time, grey scale ultrasonography- pulse echo principle is based on the pulse echo principle. a short pulse of sound, usually 2 or 3 cycles long, is produced from the transducer and transmitted into the patient , the sound wave strikes an echogenic surface in the patient and returns some of the
Real time, grey scale ultrasonography sound to the transducer. the strength of the returning sound wave determines the brightness of the image and the time it takes for the sound to travel into the patient and back to the transducer determines where the echo will be seen on the screen.
Piezoelectric Effect a piezoelectric crystal will change shape or thickness when subjected to a voltage pulse. Rapid pulses of electrical energy are converted into mechanical energy or sound waves by the vibrating crystal. returning sound waves cause
Piezoelectric Effect the crystal to vibrate, and that mechanical energy is converted into electrical energy by the transducer. this electrical signal is transformed into the gray scale image on the screen.
Transducer acts as both the sound transmitter and receiver. the operating frequency of the transducer is partially determined by the thickness of the piezoelectric crystal. the thinner the crystal, the higher is the transducer frequency.
Transducer the transducer transmits sound 0.01 % of the time. it receives returning sound waves 99.9% of the time
Positioning terminology is used by the doctor to instruct the tech what parts of the body need xrays, the directional path of the beam, may follow from entrance to exit. 1st letter= entrance, 2nd letter = exit. May indicate direction( R,L,Oblique) R&L mean patients R&L not yours
Caudal- Cd-towards the tail or Posterior describes parts of the head, neck and trunk positioned toward the tail from any given point. Also aspects of limbs, above the carpal and tarsal joints that face toward the tail
Cranial-Cr- towards the head parts of the neck, trunk and tail positioned toward the head from any given point. and aspects of limbs above the carpal and tarsal joints that face toward the head
Distal- D- part of the body or bone furthest from the main part of the body legs and feet farther away from the point of origin of a structure
Dorsal- D- back or topline above dorsal plane( horizontal mid line) upper aspect of head neck and trunk and tail. also means toward the upper aspect of the animal, also describes the legs from carpus and tarsus joints distally that face toward the head. DV view is a dorsal ventral, meaning the patient is on its abdomen
Lateral- L-outside of the leg away from midline xray beams enters through either the left or right side of the body and emerges on the opposite side there the cassette is positioned. LM view is beam comes thru the lateral area and exit the medial, outside the leg to inside the leg.
Mediolateral, Medial - M - inside of the leg Middle of patient xray beam enters a limb through the medial side and exits on the lateral side, most later radiographs or the limbs are taken in lateromedial projection in large animal radiogrpahs
Palmar- Pa- under side of front paw ( palm) used instead of caudal when describing the fore limb from the carpal joint distally, underside of the front foot from toes to ankle joint( carpus )
Plantar- Pl - underside of back paw ( sole) used instead of caudal when describing the hind limb from the tarsal joint distally, underside of the back foot from toes to the ankle joint ( tarsal)
Proximal- higher end of the extremity or bone towards the spine or top of the animal if standing near to the point of origin of a structure
Recumbent the animal is lying down when the radiograph is made. Most radiographs of the dog and cat are make this way and this position should be assumed unless otherwise stated on the radiograph
Rostral - towards the nose parts of the head positioned toward the nares(nostrils) from any given point on the head
Superior and inferior used to describe the upper and lower dental arcades respectively
Ventral - underside of head, neck trunk and tail lower aspect of the head neck trunk and tail, the term also means toward the lower aspect of the animal. ad VD is a ventral dorsal view, meaning the animals is on its back, the beam comes thru the ventral part of the patient and exits the dorsal side
Abbreviations of animal positioning L=left, R= right, Dorsal = D, Ventral = V, Cranial=Cr, Caudal = Cd, Rostral= R, Medial = M, Lateral = L, Proximal= Pr, Distal= D, Palmar= Ps or P, Plantar= Pl, Oblique= O
Oblique radiographic view taken at an angle. visualizes structures normally hidden by other structures
positioning basic criteria to find the most suitable posture to produce an accurate reproduction of the anatomic area. 1. welfare of the patient 2. restraint and immobilization of the patient 3. minimal trauma to the area of interest 4. least risk of exposing those assisting xray
Measurement equipment Caliper is used to measure the anatomic area. it measures part thickness in centimeter increment, when in doubt measure the thickest part. make 2 separate xrays with different exposures to make sure you have a good xray.
Anatomical directional terms for oblique views dorsomedial-palmarolateral oblique (upper left side)Dorsolateral-palmaromedial oblique ( upper right side) Palmaromedial dorsolateral oblique ( lower left side) Palmarolateral dorsomedial oblique ( lower right side) dorsopalmer towards head,
Anatomical directional terms for oblique views palmarodorsal toward tail, lateral to the right of middle, medial is the middle
Required view a 2 dimensional picture of a 3 dimensional structure, 2 views are taken at right angles to each other are the minimum recommended. 2 exemplify with a fractured bone, the lateral view may appear normal the crainocaudal view may
Required view visualize the fracture. position area of interest closest to the film.this reduces distortion and magnification of the are. if a limb is being xray'd it may be helpful to xray the opposite corresponding limb for comparison.
Collimation the smallest field size possible should be used for any given area of the body. EX when xraying the carpus of a cat, the collimator light should include the carpus and a small portion of the long bones distal and proximal to the carpus.
Collimation exposing a large area surrounding the carpus is not necessary. in fact such an exposure increase the amount of scatter radiation which decrease the contrast
Positional terms -Positioning guidelines the central xray beam should be centered directly over the area of interest. EX if the beam is centered over the caudal border of the 13th rib for a study of the abdomen, the entire abdomen is included ( assuming the proper size cassette is used)
Positioning guidelines the measurement for an anatomic region should be taken over the thickest area, this ensures that all regions of the part of interest will be penetrated with sufficient exposure factors. specific anatomy must be included for each area.
Positioning guidelines EX all pictures of long bones ( humerus and femur) should include the shaft of the bone, as well as the joints both distal and proximal to the bone. for joint xrays the beam must be
Positioning guidelines centered over the joint space and include a portion of the long bones both proximal and distal
Patient preparation patient s/b clean and free of debris, if the coat is wet or full of debris, confusing artifacts can appear. collars, harnesses and leashes of any sort should be removed. bandages,
Patient preparation splints and casts should be removed before xray unless there is a reason for leaving them in place. Pedal radiograph of the horse may require cleaning the frog and removing the shoe to prevent artifacts. for small animal abdomen, the GI
Patient preparation tract must be free of ingesta and fecal material. a cathartic like an enema or laxative may be indicated to remove obstructions
Positioning aids should not be placed over or under the area of interest because non are completely nonradiopaque. foam tends to produce an air density shadow and absorb and retain liquids that may be radiopaque when dry
Film identification placement a marker must be used for R or L side of patient. anatomic areas that are symmetric ( dorsoventral view of dog skull) or anatomically identical to another areas( equine limb distal to the carpus and tarsus) are difficult to distinguish without labels.
Film identification placement EX later view of the front fetlock joint of a horse must be labeled " Left (L) Front" R & L should be placed on the appropriate side of the animal. when a lateral projection of an abdomen or thorax is taken, the marker should indicate
Film identification placement the side that is down on the table. for an extremity the marker should be placed cranial to ( in from of) the leg. taking sequential xrays with appropriate numbers that identify time elapsed or order taken is also important. EX like GI contrast study
Film identification placement require sequential radiographs over a period of time, in such instance each set of xrays must be labeled with appropriate time elapsed ( hours and minutes)
Feline patients tend to resist too much restraint and canines respond to a calm, authoritative approach to restraints
Median plane is the middle of the body
Sagittal plane less than center
Transverse plan the vertical plan that cuts an animal in half
Quality assurance A system of activities, the purpose of which is to provide assurance that overall quality control is being done effectively. The system involves continuing education on the adequacy and effectiveness of the overall quality control program and
Quality assurance initiates corrective measures where necessary
5 activities of quality assurance (1) preventive maintenance, (2) quality control, (3) equipment calibration, (4) in-service education of the personnel responsible for radiography, and (5) other items such as the evaluation of new products.
Quality control being just one aspect of the quality assurance programThe overall system of activities, the purpose of which is to provide a quality product or service that meets the needs of the users. The aim of quality control is to provide quality that is
Quality control satisfactory, adequate, dependable, and economic.
quality assurance/quality control (QA/QC) 3 purposes 1st-it provides a way to minimize the dose of radiation to the patient and staff who are assisting. 2nd-allows image of quality radiographs that provide information for an accurate diagnosis.
quality assurance/quality control (QA/QC) 3 purposes 3rd- its use leads to a decreased number of repeated films and thereby reduces overall cost per examination.
imaging equipment for QA/QC The actual equipment used to perform quality control testing depends on the size of the facility or practice. For a small facility, the equipment listed following is sufficient for an informative quality control testing protocol.
imaging equipment for QA/QC These items should be stored within easy access—and together—to eliminate confusion and delay when it is time to conduct the tests. Most of these tests are done only annually; if this is not the case, it is noted in the test procedure.
imaging equipment for QA/QC-Tracking Charts to provide a means to record the data for ease in interpretation and tracking results. no right or wrong except for sensitometry/densitometry tests. The charts that the technician makes and relies on for tracking the equipment
imaging equipment for QA/QC-Tracking Charts parameters are the mainstay of the quality assurance program. When the charts indicate to the technician that the control limits have been reached or exceeded, action should be taken immediately.
imaging equipment for QA/QC- Procedures The procedures for using the test equipment are described in detail with each test. The following tests can be conducted frequently, as they are easy to do and provide the practice with a quick look at the physical nature of the radiographic
imaging equipment for QA/QC- Procedures equipment and the environment.
imaging equipment for QA/QC- equipment needed Graph paper or commercially prepared tracking charts -Pencil and ruler -Notebook or folder for retention of tracking charts -Sensitometer -Densitometer -Thermometer -Nine pennies -
imaging equipment for QA/QC- equipment needed Tape measure --Carpenter's level -Screen-film contact mesh - Simple instructions for use and interpretation
SOURCE-IMAGE DISTANCE (SID- source image distance) MARKS needs a tape measure and carpenters level. Objective : to ensure accuracy of the SID.
SOURCE-IMAGE DISTANCE (SID- source image distance) MARKS - procedure 1.Using a steel measuring tape, measure from the focal spot mark on the tube housing to the tabletop. If there is no mark on the tube housing, simply divide the tube housing end cap into fourths.
SOURCE-IMAGE DISTANCE (SID- source image distance) MARKS - procedure Using the bottom fourth as the focal spot, mark this on the end cap with a permanent marker and proceed with the measurement.
SOURCE-IMAGE DISTANCE (SID- source image distance) MARKS - procedure 2. Measure from the tabletop to the top of the cassette in the Bucky tray. 3.Add these two numbers. They should equal the SID that is marked
SOURCE-IMAGE DISTANCE (SID- source image distance) MARKS - procedure Measure the marks on the tube stand for accuracy as well. Replace any “missing” marks with permanent marker, nail polish, or paint. If the collimator has a tape measure on it, check this for accuracy with the external tape measure.
SOURCE-IMAGE DISTANCE (SID- source image distance) MARKS - procedure This information should be recorded for comparison and included in the quality control tests notebook or file.
PERPENDICULARITY -Equipment / objective Carpenters level. Objective - To ensure that the x-ray beam is properly centered, we must be sure that the tube stand, collimator, and x-ray tube are perpendicular and properly aligned.
PERPENDICULARITY- porcedure 1.When the x-ray tube is positioned in the normal position, use the level to confirm that the tube is level and parallel with the table. Stand at the end of the table and look at the tube, collimator, and tube stand.
PERPENDICULARITY- porcedure Visually verify that they appear to be perpendicular. Stand alongside the table and verify the same information regarding perpendicularity of the collimator, x-ray tube, and tube stand.
PERPENDICULARITY- porcedure 3. If the tube, the collimator, or the tube stand looks crooked or canted, adjust it or have it repaired before attempting any alignment tests or taking any radiographs. record info along with whether the test was negative, what was canted, and how
PERPENDICULARITY- porcedure it was corrected. If the equipment was serviced, the repair report should be kept for future reference. The information should be recorded for comparison.
TUBE/TABLE/CRANE LOCKS -equipment and objective Equipment Needed - None. Objective -To check the function of the locks to eliminate any unnecessary motion from the x-ray tube, table, or crane.
TUBE/TABLE/CRANE LOCKS - procedure 1. Physically place locks on and off to see whether they lock securely and unlock properly. 2. Check to make sure that the lock switch itself is not broken and that it functions properly. This should be recorded for future reference.
QA/QC TESTS FOR THE X-RAY APPARATUS X-RAY FIELD LIGHT - equipment and objective Equipment needed - water and cloth. Objective- To ensure that the field light can be seen properly with the normal lights on in the radiographic room.
QA/QC TESTS FOR THE X-RAY APPARATUS X-RAY FIELD LIGHT- procedure 1.Turn off the power to the machine. Wash the plastic covering of the collimator with warm water and mild soap. The plastic covering over the tube output area should be clean and free of debris and dirt. If not, artifacts can show up on the radiograph.
QA/QC TESTS FOR THE X-RAY APPARATUS X-RAY FIELD LIGHT- procedure (Note: On some older equipment, the plastic covering may be part of the filtering of the x-ray beam. If this is the case, do not damage or remove it without having a service person correct the filtration on the equipment.)
QA/QC TESTS FOR THE X-RAY APPARATUS X-RAY FIELD LIGHT- procedure 2. Turn on the power to the machine. To check the brightness of the light, leave room lights on and turn on the collimator light. If there is no difficulty in seeing the edges of the field, there is no problem.
QA/QC TESTS FOR THE X-RAY APPARATUS X-RAY FIELD LIGHT- procedure 3. If the dimensions of the light field are difficult to see, there is a problem. A service person should be called to increase the light intensity, and a record should be made for future comparison and reference.
LIGHT FIELD SIZE - equipment and objective • Steel tape measure - Objective To ensure that the light field determined by the collimator dials is accurate.
LIGHT FIELD SIZE- procedure 1. Using the tape measure, verify the SID to the tabletop. 2. Set the collimator size indications at some field size. Remember to use the score for the SID you use routinely. An example of a field size to use is 8 × 10 inches collimator light.
LIGHT FIELD SIZE- procedure 3. Turn on the 4. Using the tape measure, measure the light field on the tabletop. This measurement of the SID for light field accuracy.
LIGHT FIELD SIZE- procedure should be within 2% This measurement should be within 2% of the SID for light field accuracy. This should be recorded for future comparison and reference.
QA/QC TESTS FOR THE X-RAY APPARATUS COLLIMATOR/CONES/DIAPHRAGMS equipment If the x-ray equipment does not have a lighted collimator but uses slide-in diaphragms to collimate to the cassette sizes this test should be conducted. Equipment Needed- • One cassette to match each of the cone/diaphragm sizes or diameters
QA/QC TESTS FOR THE X-RAY APPARATUS COLLIMATOR/CONES/DIAPHRAGMS- objective Obective - To ensure that the cones or diaphragms used are the correct size for the cassettes available for use within the practice.
QA/QC TESTS FOR THE X-RAY APPARATUS COLLIMATOR/CONES/DIAPHRAGMS - procedure 1. Slide the different cones/diaphragms into or onto the x-ray tube, one at a time. 2. Place the appropriate size cassette in the Bucky tray (be sure to recheck the SID). 3. Make an exposure.
QA/QC TESTS FOR THE X-RAY APPARATUS COLLIMATOR/CONES/DIAPHRAGMS - procedure Use a technique for this exposure that is approximately that for fetlock or carpus.
QA/QC TESTS FOR THE X-RAY APPARATUS COLLIMATOR/CONES/DIAPHRAGMS - procedure 4. Develop this film. The corners of the developed film will be clear (as if cut off) if the cone/diaphragm used matched the size of the cassette used in the Bucky tray. If there is no
QA/QC TESTS FOR THE X-RAY APPARATUS COLLIMATOR/CONES/DIAPHRAGMS - procedure Bucky tray and all the radiographs are done tabletop, then do this test tabletop, making sure that the SID is accurate. Record this information in the QA/QC file for future reference.
QA/QC TESTS FOR THE X-RAY APPARATUS LOCKS/CABLES/OVERHEAD CRANE MOVEMENT - equipment and objective Equipment Needed - None, except the x-ray equipment. Objective -To ensure adequate locking and movement so that the x-ray tube does not drift during the exposure.
QA/QC TESTS FOR THE X-RAY APPARATUS LOCKS/CABLES/OVERHEAD CRANE MOVEMENT - procedure 1. Lock and unlock the locks. When each lock is in the locked position, the item that you are testing should not be able to move. For example, if you are testing the Bucky tray lock, then in the locked position, you should not be able to move it. If you
QA/QC TESTS FOR THE X-RAY APPARATUS LOCKS/CABLES/OVERHEAD CRANE MOVEMENT - procedure are testing x-ray tube motion, then in the locked position, you should be unable to move the x-ray tube. 2. To assess the overhead crane movement, the x-ray tube must be moved around its known limitations.
QA/QC TESTS FOR THE X-RAY APPARATUS LOCKS/CABLES/OVERHEAD CRANE MOVEMENT - procedure The tube should move easily and without obstruction. Record this information for future reference.
QA/QC TESTS FOR THE X-RAY APPARATUS ANGULATION INDICATOR - equipment and objective Equipment Needed -Carpenter's level , protractor. Objective - To ensure that the angle indicator is correct when using any angulation on the x-ray tube for a radiographic exposure.
QA/QC TESTS FOR THE X-RAY APPARATUS ANGULATION INDICATOR-procudure 1. Place the carpenter's level on the tabletop—it should be level. 2. Place the carpenter's level on the bottom of the collimator—this also should be level. 3. Note that at both places the appropriate indicators should be zero.
QA/QC TESTS FOR THE X-RAY APPARATUS ANGULATION INDICATOR-procudure 4. Rotate the x-ray tube to 15 degrees, and using the protractor, measure the degree of angulation. This should also be 15 degrees. 5. Repeat this rotation of the x-ray tube to 30
QA/QC TESTS FOR THE X-RAY APPARATUS ANGULATION INDICATOR-procudure and to 45 degrees, reading the angle indicator and measuring each degree change with the protractor . Record this information for future reference
QA/QC TESTS FOR THE X-RAY APPARATUS VIEW-BOX UNIFORMITY - equipment equipment- Light meter -You can use a photographic light meter if it has a measurement scale. With certain types of photographic light meters, the denominator of the shutter-speed light intensity is in foot-candles.
QA/QC TESTS FOR THE X-RAY APPARATUS VIEW-BOX UNIFORMITY - objective To ensure uniform bulb intensity and color for even-light transmittance in radiographic evaluation.
QA/QC TESTS FOR THE X-RAY APPARATUS VIEW-BOX UNIFORMITY - procedure 1. Unplug the view box from the electrical outlet. Clean the view box inside and out. Use a soft cloth and warm water with mild soap. Do not use nail polish remover or other harsh abrasives
QA/QC TESTS FOR THE X-RAY APPARATUS VIEW-BOX UNIFORMITY - procedure because they will scratch the view-box surface. 2. When cleaning inside, ensure that the bulbs are the same brand and the same color (e.g., daylight or soft white). 3. To measure the intensity of the lights, turn on the view box 2
QA/QC TESTS FOR THE X-RAY APPARATUS VIEW-BOX UNIFORMITY - procedure minutes before doing the test. This allows the bulbs to stabilize. 4. Turn off all the room lights. 5. Measure the intensity with the light meter at three different areas on the viewer.
QA/QC TESTS FOR THE X-RAY APPARATUS VIEW-BOX UNIFORMITY - procedure 6. Calculate the average of the intensity on the viewer. An average or normal range is 400 to 580 foot-candles. Record this average information to monitor the life of the bulbs and their intensity as they age.
QA/QC TESTS FOR THE X-RAY APPARATUS LIGHT FIELD/X-RAY FIELD ALIGNMENT - equipment and objective Equipment Needed -Nine pennies ,10- × 12-inch cassette loaded with film. Objective-To ensure that the x-ray field is actually going where the light field indicates.
QA/QC TESTS FOR THE X-RAY APPARATUS LIGHT FIELD/X-RAY FIELD ALIGNMENT-procedure 1. Center the x-ray tube over the table. 2. Set the SID to 40 inches or your normal SID, and verify that the collimator is level. 3. Put a cassette in the Bucky tray. 4. Center to the tray under the table.
QA/QC TESTS FOR THE X-RAY APPARATUS LIGHT FIELD/X-RAY FIELD ALIGNMENT-procedure 5. Set the collimator field indicators at a field that is approximately 6 × 8 inches. 6. Turn the collimator light on. Place one penny in the middle of each edge of the light field inside the light and one penny in the middle of each edge of t
QA/QC TESTS FOR THE X-RAY APPARATUS LIGHT FIELD/X-RAY FIELD ALIGNMENT-procedure he light field outside the light. The edges of the pennies should have the light field running between them, but the pennies should be touching 7. Make an exposure. The technique should be approximately the same as for a carpus or a stifle.
QA/QC TESTS FOR THE X-RAY APPARATUS LIGHT FIELD/X-RAY FIELD ALIGNMENT-procedure 8. Develop the film. When developed, the radiograph should show the pennies just as they were placed on the table, on either side of the light field. If it does not, the collimator needs adjustment. The width of a penny is 0.75 inch, and 2% of a
QA/QC TESTS FOR THE X-RAY APPARATUS LIGHT FIELD/X-RAY FIELD ALIGNMENT-procedure 40-inch SID is 0.8 inch. Therefore if the x-ray field is off by the width of one penny, it is time to call service personnel. To ensure that the center of the light and the x-ray field are aligned, draw diagonally from corner to corner on the film itself
QA/QC TESTS FOR THE X-RAY APPARATUS LIGHT FIELD/X-RAY FIELD ALIGNMENT-procedure (all four corners). Make the same drawing from corner to corner on the exposed part. These two pairs of “Xs” also should not be apart by more than 2% of the SID. If they are, realignment by service personnel is necessary.
QA/QC TESTS FOR THE X-RAY APPARATUS LIGHT FIELD/X-RAY FIELD ALIGNMENT-procedure Record this information in the QA/QC file for future reference.
QA/QC TESTS FOR THE X-RAY APPARATUS SCREEN-FILM CONTACT equipment and objective Equipment Needed -Copper wire mesh contact tool with ⅛-inch spacing of the wires, Densitometer. Objective To ensure that the adhesive on the back of the screens within the cassettes is still holding the screen tightly.
QA/QC TESTS FOR THE X-RAY APPARATUS SCREEN-FILM CONTACT = procedure 1. Each cassette to be tested should be allowed to sit for about 10 minutes before this test is performed. This allows any trapped air (from loading the film) to dissipate. 2. Place the cassette on the tabletop. 3. Place the cassette so
QA/QC TESTS FOR THE X-RAY APPARATUS SCREEN-FILM CONTACT = procedure that the long axis is perpendicular to the anode-cathode axis of the x-ray tube. This is to minimize the anode heel effect. 4. Place the wire mesh over the cassette. 5. Use an SID of at least 40 inches. 6 Cone down to the size of the cassette.
QA/QC TESTS FOR THE X-RAY APPARATUS SCREEN-FILM CONTACT = procedure 7. Make an exposure using approximately a carpus or a stifle technique for tabletop. 8. Process the film. 9. When viewing the film, place it on a view box in a dimly lit room.
QA/QC TESTS FOR THE X-RAY APPARATUS SCREEN-FILM CONTACT = procedure 10. Stand 6-8 ft back from viewer, look for areas of darkness, unsharpness, areas of poor contact appear as dark areas on the film. If the area of darkness is in the middle of the cassette or where you would likely put the area of interest the screen
QA/QC TESTS FOR THE X-RAY APPARATUS SCREEN-FILM CONTACT = procedure should be adjusted This may be as simple as regluing the edges of the screen to the felt. Any household white glue (e.g., Elmer's) can be used, or you can use double-backed tape (e.g., carpet tape). The screens in the cassette may need
QA/QC TESTS FOR THE X-RAY APPARATUS SCREEN-FILM CONTACT = procedure to be replaced. This test must be done on all cassettes.
QA/QC TESTS FOR THE X-RAY APPARATUS UNIFORMITY OF SCREEN SPEED equipment equipment- Control cassette for each speed within the practice (usually one that is the newest or most consistent for exposure) -Densitometer , One box of film, to be used with each screen size within the practice.
QA/QC TESTS FOR THE X-RAY APPARATUS UNIFORMITY OF SCREEN SPEE-D Objective Objective To determine periodically whether screens have lost speed through wear and tear.
QA/QC TESTS FOR THE X-RAY APPARATUS UNIFORMITY OF SCREEN SPEED -procedure Before starting, visually inspect each cassette for properly functioning locks, intact hinges, and screen-felt contact. The screens should be checked for scratches, worn spots, or chips and should be clean.
QA/QC TESTS FOR THE X-RAY APPARATUS UNIFORMITY OF SCREEN SPEED -procedure 1.Sort all the cassettes by screen type or speed group (high-speed, par, detail, rare-earth). Test each speed group separately. 2. Select one cassette from a sorted speed group as the control cassette.
QA/QC TESTS FOR THE X-RAY APPARATUS UNIFORMITY OF SCREEN SPEED -procedure Record the number of this cassette so that you can repeat this test when needed. 4. Load the cassettes from the film box designated for this procedure. Cutting a 14×17-in film into fourths and placing one fourth into one corner of each
QA/QC TESTS FOR THE X-RAY APPARATUS UNIFORMITY OF SCREEN SPEED -procedure cassette helps limit the cost of this procedure. Just remember which corner of the cassette has the film in it. 5.SID should be at least 50 inches if possible. You may have to put the cassettes on the floor to get this distance.
QA/QC TESTS FOR THE X-RAY APPARATUS UNIFORMITY OF SCREEN SPEED -procedure 6. Place the corners of the cassettes together. 7 Center the x-ray tube over the area where the cassettes meet. 8. Cone down to approximately 8- × 8-inch field
QA/QC TESTS FOR THE X-RAY APPARATUS UNIFORMITY OF SCREEN SPEED -procedure 9. Mark the cassette that is the control, and place this cassette into the upper-right-quadrant position of the four cassettes 10. Make an exposure, using approximately a carpus or a stifle technique. A technique that could be used for a medium-
QA/QC TESTS FOR THE X-RAY APPARATUS UNIFORMITY OF SCREEN SPEED -procedure speed system is 10 mAs at 50 to 60 kVp. For a faster speed system, 5 mAs at the same range of kVp would be acceptable.
QA/QC TESTS FOR THE X-RAY APPARATUS UNIFORMITY OF SCREEN SPEED -procedure 11. Process these films. 12. Read the density of each film in the center on the densitometer. 13. Record the density for each screen. 14. Repeat this procedure until all the screens within the same speed group have been tested.
QA/QC TESTS FOR THE X-RAY APPARATUS UNIFORMITY OF SCREEN SPEED -procedure 15. Determine the average density of the films for each speed group. Divide the measured density of each film by the density of the control to determine each screen's ratio. 16. If there is more than one speed in the practice, this
QA/QC TESTS FOR THE X-RAY APPARATUS UNIFORMITY OF SCREEN SPEED -procedure procedure must be repeated for the other speed groups, starting from the choice of a control cassette to the recording of the densities. The range of acceptable ratios between screens is between 0.85 and 1.15. Any screen that falls
QA/QC TESTS FOR THE X-RAY APPARATUS UNIFORMITY OF SCREEN SPEED -procedure outside the ratio range should be removed from service. Record this information for future reference.
QA/QC TESTS PARAMETERS FOR CALIBRATION (kVp, mA, TIMER, AND FILTRATION) Calibration should be conducted at least annually. The rationale for calibrating the x-ray equipment is to ensure that when 80 kVp is chosen, 80 kVp is delivered. Likewise, it is done to ensure that the mA stations and the timer are correct.
QA/QC TESTS PARAMETERS FOR CALIBRATION (kVp, mA, TIMER, AND FILTRATION) Calibration involves a series of tests that a serviceperson must perform. For example, a parameter that can change is kilovoltage. As an x-ray machine ages, kilovoltage can fluctuate. This problem also can be caused by incoming line voltage.
QA/QC TESTS PARAMETERS FOR CALIBRATION (kVp, mA, TIMER, AND FILTRATION) Many veterinary clinics do not have a dedicated line for the radiographic equipment, and the voltage can change dramatically with an increase or a decrease in the incoming line voltage. This, of course, affects the penetration on the radiographs.
QA/QC TESTS PARAMETERS FOR CALIBRATION (kVp, mA, TIMER, AND FILTRATION) Another possible source of kilovoltage fluctuation is bad internal workings—a computer chip, board, or drive that is not functioning correctly. These problems will be apparent in radiographs that are incorrectly penetrated and need to be repeated.
Darkroom Quality Control Darkroom cleanliness is so important for good film processing that it is addressed separately. Just wiping up the counter is not enough, but it is a start. There must be no eating and no smoking in the darkroom.
Darkroom Quality Control Crumbs in the cassettes can cause artifacts that could be interpreted as part of the diagnosis for the patient. Remember that the lit end of a cigarette is not a “safe” light and can fog your radiographs.
Darkroom Quality Control This type of fog is called darkroom fog. Darkroom fog, no matter what the cause, is unacceptable. Fog can be caused by white-light leaks from around a door, cracked safelights, improper-wattage bulb in the safelight, improper safelight filter,
Darkroom Quality Control safelight too close to the counter with a too-high wattage bulb, improper chemical temperature, or improper chemical balance.
QA/QC TESTS FOR THE X-RAY APPARATUS FOG TEST equipment and objective equipment: Lightly exposed radiograph ,Watch or timer , Densitometer. Objective: To assess any fog in the darkroom that may be adding unwanted density to the radiograph during processing.
QA/QC TESTS FOR THE X-RAY APPARATUS FOG TEST -procedure 1. Expose a cassette with a film in it, using a smallextremity technique. 2. Take the cassette into the darkroom. 3. Remove the film from the cassette, place the film on the counter, and cover half of it with the cassette.
QA/QC TESTS FOR THE X-RAY APPARATUS FOG TEST -procedure 4. All the safelights should be on, as in routine processing of a radiograph. 5. Leave the film and cassette in this position for 2 minutes by the watch or timer 6. Process the film normally.
QA/QC TESTS FOR THE X-RAY APPARATUS FOG TEST -procedure 7. When the film has been processed, notice the difference. 8. Measure each side of the radiograph with the densitometer. The difference should be no greater than 0.08 optical density
QA/QC TESTS FOR THE X-RAY APPARATUS FOG TEST -procedure (OD) for routine film-screen combinations and routine darkroom processing. If the difference is greatert han 0.8 OD, the source of the radiographic fog must be located . This test should be done quarterly because it provides a good follow-up
QA/QC TESTS FOR THE X-RAY APPARATUS FOG TEST -procedure on fog. Record this information for future reference.
QA/QC TESTS FOR THE X-RAY APPARATUS SENSITOMETRY AND DENSITOMETRY equipment Film, one box designated for sensitometry (this should be the same type/speed used every day but of the smallest size [i.e., 8 × 10 inches]) , Sensitometer , Densitometer , Sensitometry graph paper,Thermometer.
QA/QC TESTS FOR THE X-RAY APPARATUS SENSITOMETRY AND DENSITOMETRY-objective To ensure that the processing of the radiographs is optimized, thereby providing the best quality radiograph. This is done by testing the processing procedure using a constant nonradiographic light source.
QA/QC TESTS FOR THE X-RAY APPARATUS SENSITOMETRY AND DENSITOMETRY-procedure 1. in the dark room take the temperature of the developer. 2. Using the sensitometer, expose one edge of a piece of radiographic film from the box of film dedicated for sensitometry. 3. Process the film normally.
QA/QC TESTS FOR THE X-RAY APPARATUS SENSITOMETRY AND DENSITOMETRY-procedure 4. After the film has been processed, read the optical density of the steps with the densitometer and record the result on the graph paper according to the following procedure. 5. Measure the density in the center area of the film without any exposure.
QA/QC TESTS FOR THE X-RAY APPARATUS SENSITOMETRY AND DENSITOMETRY-procedure 6. Plot this densitometer reading (number) in the base + fog area on the graph. 7. The base + fog should not increase more than + 0.05 from the original or normal reading. 8. Next, read the steps of the sensitometry exposure and record the
QA/QC TESTS FOR THE X-RAY APPARATUS SENSITOMETRY AND DENSITOMETRY-procedure numbers on either the film or a piece of scratch paper. These numbers determine which step should be used for the contrast strip and the speed strip. 9. From these numbers, determine
QA/QC TESTS FOR THE X-RAY APPARATUS SENSITOMETRY AND DENSITOMETRY-procedure which step is within a density range of 1 to 1.3. This is known as the speed step. 10. Plot the density reading for the speed step in the area on the graph. This step is used for the speed
QA/QC TESTS FOR THE X-RAY APPARATUS SENSITOMETRY AND DENSITOMETRY-procedure step for the entire box of sensitometry film. Variations should not be greater than ± 0.15 of the initial reading. If they are beyond this parameter, corrective action must be taken.
QA/QC TESTS FOR THE X-RAY APPARATUS SENSITOMETRY AND DENSITOMETRY-procedure 11. Using the numbers for the steps off the scratch paper, determine the density of the steps above and below the speed step. 12. Subtract these two densities for the reading for the contrast strip. These two steps will be used for the contrast
QA/QC TESTS FOR THE X-RAY APPARATUS SENSITOMETRY AND DENSITOMETRY-procedure strip for the entire box of sensitometry film. 13. Plot this number on the graph portion for contrast. The variations should not be greater than ± 0.2. If they are beyond this parameter, corrective action must be taken 14. These
QA/QC TESTS FOR THE X-RAY APPARATUS SENSITOMETRY AND DENSITOMETRY-procedure densities from the same steps on the sensitometry strip should be read and plotted daily on the graph paper.
QA QC KEY POINTS 1. The purpose of a QA/QC program is to provide a way to minimize the dose of radiation to the patient and personnel, to allow production of quality radiographs to help with an accurate diagnosis, and to decrease the number of repeated films.
QA QC KEY POINTS 2. QA/QC tests are intended to be interpreted objectively. Opinions and personal preferences are inappropriate, 3. The majority of QA/QC tests must be performed annually;
QA QC KEY POINTS however, it is important to check the required frequency of each test because some have other than annual schedules. responses.
Technical Common artifacts and causes- film too dark Overexposure due to too much kVp or mAs Over development due to extended time in developer or increased developer temperature Over measurement of part under examination
Common artifacts and causes- film too light Underexposure due to insufficient kVp or mAs Underdevelopment due to decreased temperature or time of development, developer exhausted or diluted X-ray tube failure,Incorrect film-screen combination,
Common artifacts and causes- film too light Machine timer out of calibration ,Drop in incoming line voltage
Common artifacts and causes-Film gray/lack of contrast Too much kVp, Radiation fog due to exposure of film to radiation other than desired exposure, Light leak in darkroom, Storage fog due to conditions that are too hot or too humid Chemical fog due to old chemicals, increased chemical
Common artifacts and causes-Film gray/lack of contrast temperature, or increased time of development, Film out of date, Lack of a grid with use of high kVp, Double exposure, Incorrect bulb wattage or filter for safelight in darkroom
Common artifacts and causes-Lack of detail Increased object—film distance Blurring due to patient motion Blurring due to poor screen-film contact Blurring due to x-ray tube motion Distorted image due to central x-ray not directed at center of film Double exposure
Common artifacts and causes-Heavy lines on radiograph (generalized) Grid lines due to: Grid out of focal range Grid out of alignment to x-ray central beam Grid upside down Damaged grid Roller marks as result of film jammed in automatic processor
Common artifacts and causes-Inconsistent film density Collimation of primary beam Bucky tray not positioned directly under primary x-ray beam Cassette not locked into Bucky tray correctly Light leak into cassette Quantum mottle Target damage (pitted anode) Variable screen-film contact
Common artifacts and causes-Black marks (not generalized) Crimping or folding of film Two films sticking together during development Static electricity Developer on film before processing Fingerprints as a result of developer on hands while loading or unloading cassette
Common artifacts and causes-Clear areas on film (white marks not generalized) Hair in cassette, Scratch in film emulsion, Line due to scratch on screen surface, Contrast medium on cassette or table Air bubble on film during developing procedure,
Common artifacts and causes-Clear areas on film (white marks not generalized) Film touching side of tank during manual processing, Fingerprints due to film handling with contaminated hands
Common artifacts and causes- Yellow radiograph Fixer splashes on film before developing Premature age due to improper fixation Film sticking together during fixing process Incomplete washing so that residual fixer oxidizes to yellow powder while destroying the image
This radiograph exhibits a blurred image that lacks detail and definition a classic example of motion. The most common cause is patient movement during exposure. Patient motion is the most common artifact in xraying animals.use sedation/restraint.for panting, hold muzzle closed or giving a short, quick blow on the nose while
This radiograph exhibits a blurred image that lacks detail and definition making the exposure can effectively stop rapid respiration temporarily. or use is a short exposure time using highest mA .Another cause of a blurred radiographic image is x-ray tube or cassette motion. sturdy tube stand and cassette holder can minimize
radiograph exhibits a general lack of density. radiograph lacks sufficient (kVp) or(mAs). Insufficient exposure may cause this, or more than the image is light: the background (area surrounding the patient anatomy) is also light.
radiograph exhibits a general lack of density. This type of insufficient film density can be the result of faulty film processing,incorrect film-screen matching, or an x-ray machine out of calibration. process solution expired or too cold,
radiograph exhibits a general lack of density. not in developer for sufficient time. An incorrect film-screen combination can result in a radiograph that is too light or too dark. The intensifying screens must match the film being used. If there is any question, the manufacturer should be consulted.
Improper film handling is the cause of this radiographic artifact A black “tree” pattern or a linear dot patterncaused by a static electrical charge released on the film. Static electricity is most common in dry winter months, when the darkroom has relatively low humidity. To avoid static, eliminate friction by
Improper film handling is the cause of this radiographic artifact removing the x-ray film from the storage box slowly and placing it in the cassette without dragging across any surface
two identical images are actually superimposed. This radiograph is an example of a double exposure.exposure button twice. could be that the audible exposure indicator (“beep” or “ding” during exposure) malfunctioned and a second exposure was then taken. If there is any question of machine function
Finger pressure mark artifact called a finger crescent; occurs when the tech is in a hurry to remove the x-ray film from the cassette. When two fingers are placed on the film a small distance apart and pinched together
Finger pressure mark artifact to remove the film from the cassette, a black crease mark can result from the pressure placed on the film by the fingertips. To avoid this and similar artifacts, x-ray film should be handled by the edges only
poor animal preparation artifacts The gray streaks are the result of a wet haircoat. inhibit a proper diagnosis or even mimic a pathologic lesion. Radiopaque contrast media, urine, blood, or water can create this artifact.
poor animal preparation artifacts Before any radiograph is exposed, debris should be removed and the haircoat should be dry.
Film folding in cassette-artifacts when a tech is in a hurry and corners are not in place, creates a dark line across the radiograph and a mirror image on either side of the crease.
result of a foreign object in the cassette-artifacts a piece of paper that was inadvertently placed in the cassette during the film loading process.manufacturers supply x-ray film with a sheet of thin paper between each piece. easy to not see and remove
a scratch in the emulsion artifact the emulsion can become marred through contact with adjacent hangers or other projections. Scratched emulsion is a common occurrence when a number of films are developed at one time. true with the use of tension clips instead of channel clips
film fog- artifact -Increased blackness, usually regional or global Definition: any unwanted film exposure /development Decreased image contrast and detail Unwanted light (1) the film bin door is ajar, (2) a film box lid is loose or damaged, or (3) the cassette is not closed properly or is damaged.
radiopaque contrast media artifact Contrast media are used for special radiographic procedures such as an upper gastrointestinal study or cystogram . Whenever radiopaque contrast media are used the possibility of spillage exists. If a contrast medium is present on the
radiopaque contrast media artifact cassette or on the xray table, it will prevent the x-rays from reaching the film, To minimize the occurrence of this artifact, the tabletop and cassettes should be monitored and cleaned frequently
portion of the film being unexposed Two primary causes for the type of artifact shown here are (1) the central x-ray is not perpendicular to the cassette and (2) the cassette is not directly under the entire primary xray beam. Aiming the central ray at any angle other than 90
portion of the film being unexposed degrees not only prevents the entire film from being exposed but causes geometric distortion. The cause of the artifact in this case study was not the tube angle but the cassette was not under the primary xray beam
portion of the film being unexposed the cassette must be locked into the tray with the cassette locks, the tray must be pushed completely under the tabletop, and the center of the cassette tray must be in line with the central x-ray.
The artifact in this radiograph appears as small, clear (white) areas.- fingertips dead giveaway of fault of xrays white blotches are actually fingerprints. This is most likely the result of fix solution on the hands while handling the film before processing. It is imperative that the hands be clean and dry before handling any film.
white dots inside the animal- artifacts may be buckshot, and can remain, it wont hurt the animal and may work themselves out
mottled density -artifact no animal patient between the x-ray beam and the cassette. No pattern to the mottled density appears to exist. This would indicate the presence of something on the intensifying screens. When in white light, there was a thin sheet of tissue
mottled density -artifact paper inside. As it turns out, the practice just received new cassettes and neglected to remove the tissue
The film has uneven density where the top of the film - artifact There is also a noticeable wavelike appearance over the entirebottom half of the film. Clearly, this is not an artifact that is on the animal patient because it is dispersed over the entire film. The problem here involves the
The film has uneven density where the top of the film - artifact chemical processing. This film was manually processed using hand tanks. The radiographer failed to stir the chemicals before processing, which resulted in an uneven concentration of developer in the tank.
KEY POINTS artifacts It is essential that the radiographer understand the causes of artifacts and know how to troubleshoot and correct the cause of the artifact. 2. Artifacts can mimic pathologic conditions which may lead to a misdiagnosis.
KEY POINTS artifacts 3. The most common cause of artifacts in veterinary radiology is patient motion.
grid use always use a grid between the patient and the film cassette when the body part being xrayed is greater than 10cm thick
Darkroom mistakes most mistakes made are related to the processing of radiographs. necessary to keep clean and light proof. chems should be changed, replenished and maintained and mixed according to strict directions of manufacturer
Darkroom safelight a light bulb shielded by a plastic filter that stops any light to which the film is sensitive from penetrating the filter and entering the room. , bulb not exceed 15 w or less,wattage recommended. or film will be fogged or partially exposed.
Darkroom safelight no film should be exposed to the safe light longer than necessary.
Darkroom table should be placed in darkroom for loading and unloading cassettes, located far away from processor, so liquid or dry chem will not be spilled on it. shelves above or below to store unexposed films and cassettes. Xray film must be kept in a cool dry place
Automatic film processor- must provide ventilation, ceiling exhaust fan is good small capacity 90 second processor installed without construction. larger needs construction because input tray must be outside dark room. it is necessary to maintain fresh solution and that solutions are flowing properly within processor.
Automatic film processor though these speed up the standardized film processing but require more maintenance than hand processing tanks.
Darkroom film storage it must be protected from light, exrays, gamma radiation, heat, moisture and pressure. all these my result in fogging and decreased quality. keep films in original boxes and placed in a cabinet.
Darkroom cassette loading and unloading prevent static electricity, bending, creasing scratching when film is transferred from box to cassette. hold only at corners and pull slowly and continuous from box. place carefully in cassette no edges over cassette. c
Darkroom cassette loading and unloading areful to prevent soiling or intensifying screen when film is removed
darkroom xray handling film is more sensitive after exposure than before. handle only at corners. have dry clean hands when handeling. any developer or fixer solution that touches the film before processing will create an artifact on processed film,
darkroom xray handling usually not an issue with an automated processor
darkroom silver recovery the silver contained within xray film emulsion, may be removed and recovered. most silver not exposed to xray is not converted to metallic silver and accumulates within the fixer solution. silver recovery units may be attached to the fixer to
darkroom silver recovery remove the silver by an electrolytic process. it is economical for large practice . silver can be recovered from exposed and non exposed film. few companies specialize in recycling film for silver recovery. could have small cost savings.
darkroom radiographic film quality a film of good diagnostic quality should provide excellent detail correct scale of contrast and optimal density.
radiographic detail refers to the degree of sharpness that defines the edge of an anatomic structure. represents the best reproduction or an organ.
darkroom wall color The walls of the darkroom should be painted white or cream with a good-quality, washable paint. By painting the walls a light color, more reflection of the safelight is produced, providing a more visible work environment. If the quality and
darkroom wall color intensity of the light are “safe,” the illumination reflected from any surface also is “safe,” regardless of the color of that surface.
safelight color and wattage Safelights use a small-wattage bulb and a special filter to eliminate the light from the blue and green spectrum. The light bulb should be 15 watts or less. The filter varies by manufacturer.The most common types are a brown filter (
safelight color and wattage Wratten 6B, Kodak) for blue-light-sensitive film and a dark-red filter (Wratten 6BR or GS-1) for green-light-sensitive film. special red for rare earth. The dark-red filter is recommended because of its versatility: both
safelight color and wattage green-light- and blue-light-sensitive film can be used in this lighting.
safelight positioning Safelights should be positioned so that darkroom work can be performed without fumbling. There are two types of safe lighting: direct and indirect. Direct lighting is a diffused light that shines directly over a work area such as the dry or wet
safelight positioning side of the darkroom. Indirect lighting is a filtered light directed toward the ceiling and reflected over the entire room. Indirect lighting is often combined with direct lighting. At no time
safelight positioning should the safelight be closer than 4 feet from a work area. A safelight that is too close, has a too-high wattage bulb, or has incorrect filtration may cause film fog.
Film Reticulation A darkroom artifact produced by variable chemical temperatures that cause irregular expansion and contraction of the film emulsion, resulting in a mottled density appearance.
Developing agents are composed of chemical compounds such as hydroquinone or phenidone that can convert exposed grains of silver halide to black metallic silver. The developing agent has little or no effect on the unexposed silver halide crystals.
Developing agents Accelerators are chemicals that increase the activity of the developer. Substances such as potassium carbonate or sodium carbonate are used to increase the pH to an alkaline range of
Developing agents Accelerators 9.8 to 11.4. This increase in pH causes the emulsion to swell and soften, allowing the developing agent to work more effectively.
Developing agents Preservatives prevent the rapid oxidation that can occur with alkaline developing agents. They also help maintain a stable development rate and prevent staining of the emulsion layer.
Developing agents Restrainers often potassium bromide and potassium iodide are used as restrainers or antifoggants. limit the action of the developing agent to the exposed silver bromide crystals in the film.
Developing agents Hardeners are often added to developers in automatic processors. They harden the film during processing and prevent excessive swelling of the emulsion. If the gelatin emulsion were to swell extensively, it could be damaged by the rollers in the automatic processor.
Developing agents solvent consists of water to dissolve the chemicals.
Developing agents The Rinse Bath After a film has been in the developer, it retains a substantial amount of developer in the gelatin (approximately 60 mL on a 14- × 17-inch film). If the film were transferred directly into the fixer,
Developing agents The Rinse Bath the alkaline developer would neutralize the acid of the fixer.
Developing agents The Rinse Bath Normally, the rinse bath consists of circulating water in which the film is rinsed for 30 seconds. A chemical solution such as acetic acid and water can be used as another method of stopping the development procedure. This chemical solution is
Developing agents The Rinse Bath called a stop bath. In automatic processing, a rinse or stop bath is not necessary because the rollers tend to remove excess developer from the film before it reaches the fix tank.
Developing agents Fixer After a film has been properly developed and the exposed silver halide crystals have been converted to metallic silver, one other step involving the silver crystals remains. The
Developing agents Fixer unexposed silver halide crystals remaining on the film are unaffected by the developer solution and must be removed. If these silver crystals were to remain on the film, they would discolor and darken with exposure to light.
Developing agents Fixer erves two basic purposes: (1) it clears the unexposed silver halide crystals from the film, and (2) it hardens the gelatin coating so that it can be dried without damaging the film
Developing agents Fixer surface. This process is known as fixation. The general guideline is that the film should be fixed for twice the development time to ensure maximum hardening of the
Developing agents Fixer emulsion. (Note: A radiograph can be viewed briefly after it has been in the fix for 1 minute and then returned after evaluation.)
Developing agents Fixer Clearing or fixing agents dissolve and remove the unexposed silver halide crystals from the film emulsion. The two most common clearing agents are sodium thiosulfate and ammonium thiosulfate. The agent actually changes the appearance of
Developing agents Fixer Clearing 8 the film from a milky white to a clear or transparent image. The black metallic silver portion of the film remains the same.
Developing agents Fixer Preservatives such as sodium sulfite prevent decomposition of the fixing agent.
Developing agents Fixer Hardeners such as aluminum salt prevent excessive swelling of the gelatinous emulsion during the fixation procedure and softening during the wash procedure. Hardeners shorten the drying time by essentially preventing the film from becoming waterlogged.
Developing agents Fixer Acidifiers are compounds that accelerate the action of the other chemicals and neutralize any alkaline developer possibly carried over into the acidic fix solution.
Developing agents Fixer Buffers are chemical compounds added to the solution to maintain the desired pH. Buffers stabilize the acidity against the addition of alkaline developer by carryover. Without the addition of a buffer, the alkaline developer would neutralize the acid of the
Developing agents Fixer Buffers fix solution, thus shortening the effective life of the fix. Some buffers also prevent sludge formation in the fix bath.
Developing agents Fixer Solvent consists of water. Its purpose is to dissolve the other ingredients and assist the fixing agent to diffuse into the emulsion layer of the film. Once the fixing agent is in the
Developing agents Fixer Solvent emulsion layer, it can dissolve the unexposed silver halide crystals. The solvent then helps by carrying the silver halide away from the film.
Developing agents Wash Bath The purpose of the wash is to remove the processing chemicals from the film surface. If a film is not washed properly for a long enough period, the image will eventually
Developing agents Wash Bath discolor and fade. Films should be washed in circulating water so that both surfaces of the film receive fresh water continuously. In manual processing, the average suggested
Developing agents Wash Bath wash time is 20 to 30 minutes with periodic agitation or water circulation. In automatic processing, the water system of the processor keeps a constant flow of temperate water through and around the wash rack and film.
Developing agents Wetting Agent A common problem of drip-drying films is the possibility of water spots or other drying streaks. The drying process can be hastened and some artifacts avoided by using a wetting agent bath known as a surface-tension reducing agent (a detergent).
PROCESSOR MAINTENANCE Solution level check • Replenishment rate check • Temperature check • Roller operation check • Rinsing and wiping of all roller racks • Regular cleaning of tanks
Key Points Dark room xray developing The darkroom must be clean, organized, and completely lightproof. 2. All chemicals must be kept at the same temperature to prevent reticulation. 3. Bacterial, fungal, and
Key Points algal growth are a common problem in hand-processing tanks and can be controlled by cleaning tanks with 1% chlorine bleach when they are drained. 4. Exposed x-ray film can be
Key Points processed manually in hand tanks or automatically in an automatic processor. 5. The legal requirement for keeping radiographs is 7 years; however, it is advisable to keep them until the patient dies.
Exhausted fixer solution can result in yellow radiographs. true
Developer and fixer should be changed every ________ weeks regardless of use. 7-8 week
The majority of QA/QC tests must be performed monthly. false
__________ is the exposure factor that has the greatest influence of radiographic contrast. Kv
Radiographic contrast agents contrast means density. in many rads, natural or inherent contrast of the anatomy is insufficient for a diagnosis to be make, very true in GI urogential and spinal cord disease. Addition of positive or negative contrast
Radiographic contrast agents medium can increase the density difference between anatomic structures, increasing the likelihood of correct image interpretation.
Radiographic contrast agents- 4 types of contrast medium 1.radiographic gases 2. insoluble inert radiopaque medium, 3. soluble ionic radiopaque 4. soluble nonionic radiopaque
Radiographic contrast agents Radiolucent gases( air, nitrous oxide, carbon dioxide) absorb small amounts of radiation, resulting in images of greatly reduced opacity. these agents are used primarily in double contrast gastrograms, double contrast cystograms and rarely, pneumoperitoneography.
Radiographic contrast agents Radiolucent gases( air, nitrous oxide, carbon dioxide) Contraindications for animal with severe hemorrhagic cycistiswhich gas absorbtion in circulation is increased. nitrous and carbon dioxide is safer than room air due the increased solubility is less likely to cause serious air embolization
Radiographic contrast agents - Insoluble inert radiopaque medium: barium sulfate Barium sulfate has a high atomic number and absorbs a large amount to radiation, resulting in greatly increased radiopgraphic opacity. used for upper and lower GI exams. it is inert (nonabsorbed) and fairly soothing to the GI tract. it coats the GI mucosa
Radiographic contrast agents - Insoluble inert radiopaque medium: barium sulfate better than organic iodides, improves visualization of luminal surface. comes in powder, paste or liquid. contraindications for server constipation and upper or lower bowel perforations. care with animals with aspiration pneumonia
Radiographic contrast agents- Soluble ionic radiopaque medium: iothalamte diatrizoate negatively charged iothalamate and diatrizoate are benzoic acid derivatives with 3 iodine molecules. coupled with positively charged sodium or meglumine to form a soluble salt. high atomic number of iodine increases radiation absorption
Radiographic contrast agents- Soluble ionic radiopaque medium: iothalamte diatrizoate and increases rad opacity.can be used orally for GI exam, intravascularly for venous or arterial studies and excretory urography for peritoneal cavity, bladder and urethra; intra articularly in draining wounds for fistulography, and in saivary
Radiographic contrast agents- Soluble ionic radiopaque medium: iothalamte diatrizoate ducts for sialographyionic organic iodides should not be used in respiratory tract or intrathecally for meylography. because ionic iodides are hyperosmolar salt solutions, when used intravascularly the can increase in intravascular fluid volume
Radiographic contrast agents- Soluble ionic radiopaque medium: iothalamte diatrizoate followed by somotic diuresis. the hyperosmolartiy can cause diarrhea when given orally. contraindicated in dehydrated and know iodine sensitivity patients.
Radiographic contrast agents- Soluble nonionic radiopaque medium: iohexol, iopamidol- positive contrast -high specific gravity positive contrast agents are the nonionic organic iodides. like iohexol, iopamidol and iotolan. doesn't dissociating into pos (+) and neg (-) charged ions in solution.allow agents to be used intrathecally (in cerebrospinal fluid around the spinal cord)
Radiographic contrast agents- Soluble nonionic radiopaque medium: iohexol, iopamidol for myelography and everywhere ionic iodides can be used. these agents are still hyperosmolar but much less so than the ionic organic iodides. they appear to have a lower incidence of adverse effects and contrast reactions but cost more.
Radiographic contrast agents- ionic and nonionic organic iodides may case serious contrast reactions or adverse effects when given intravenously, intra arterially or intrathecally. reactions are much less when used orally. reactions may be nausea, vomiting, hypotension , cardiac arrest and anaphalaxis. they
Radiographic contrast agents- ionic and nonionic organic iodides occur infrequently but is advisable to have a catheter in place as well as fluids and oxygen endotracheal tube and resuscitation drugs. dont leave patient alone.
esophagus contrast study use agent barium sulfate, 100% weight/volume suspension. alone or diluted to evaluate an enlarged esophagus or a thick paste if esophagus is not enlarged, mix barium with food, oral
esophagus contrast study organic iodides ( ionic or nonionic) is used when perforation of esophagus is suspected. Procedure- no prep necessary, use fluoroscopy. if non available exposure must be made when animal swallows, barium admin with a syringe into buccal pauch
Upper gastrointestinal (GI) study- stomach and small bowel-negative contrast agent-low specific gravity 3 types contrast used 1. barium sulfate 25%-30% wt/vol, 2 oral iodides and 3.negative contrast,including air, carbon dioxide and nitrous oxide. Barium is most common used for upper GI when perforation is not suspected. Negative contrast used in
Upper gastrointestinal (GI) study- stomach and small bowel combination with barium sulfate for double contrast studies. oral iodinated used when perforation is suspected because barium sulfate will not be reabsorbed once it leaks into body cavity. Procedure: no food 24 before and warm water enemas
Upper gastrointestinal (GI) study- stomach and small bowel administered 2-3 hours before. acepromazine can be used without adverse side effects on motility. Dosage: barium sulfate 10ml/kg and oral Hypaque or Gastrografin 3,;/lg
Upper gastrointestinal (GI) study- stomach and small bowel Film sequence: ventrodorsal and lateral views. immediately after given medication 2 films should be taken to completely evaluate the stomach, ventrodorsal view, a dorsoventral and both R and L later views. at 15,30 and 60 minutes,
Upper gastrointestinal (GI) study- stomach and small bowel film sequence consists of ventrordorsal and R lateral views. the same views are taken at various intervals until contrast reaches the large bowel. timing varies with patient and suspected disease
Lower gastrointestinal (GI) study- large bowel-barium enema barium sulfate 10% - 15% wt/vol or iodinated preparations like Gastrografin or oral hypaque used for lower GI's. Precautions: barium sulfate should not be used wish a perforation is suspected.
Lower gastrointestinal (GI) study- large bowel-barium enema A barium enema should not be preformed within 48 hours after a biopsy of the rectum or colon has been obtained. Preparation: fasting for 24-48 hours, may be given a GI cleansing agent like Golytely. warm water enemas must be
Lower gastrointestinal (GI) study- large bowel-barium enema given before exam , it is essential that the entire bowel be cleansed before enema preformed. A Bardex catheter and a barium container are needed for the study.
Lower gastrointestinal (GI) study- large bowel-barium enema Procedure: animal should be anesthetized, balloon tipped catheter inserted into rectum, and the cuff is inflated to form a firm seal against the colonic wall. barium or iodine is placed in
Lower gastrointestinal (GI) study- large bowel-barium enema colon by gravitational flow. 15% wt/vol barium sulfate solution is used for enema. ideally flouoroscopy is used. radiographic views needed are lateral, ventrodorsal and R and L ventrodorsal oblique. after exam completed and the barium
Lower gastrointestinal (GI) study- large bowel-barium enema evacuated air is injected to obtain a double contrast study of the large bowel
Urinary Track study-kidneys contrast agent: several kinds available for evaluation of kidneys. will use the intravenous pyelogram (IVP) which is most used. IVP or excretory urogram, performed by injection contrast medium intravenously. Ionic organic iodide used. a
Urinary Track study-kidneys meglumine diatrizoate and sodium diatrizoate prep is most common. Standard dose of contrast is 800mg of iodine per Kilogram, which may increase by 50% in patients with poor renal function.
Urinary Track study-kidneys Complications- with IVP is vomiting and anaphylactioid reactions and hypotension. vomiting is transient reaction of short duration and not serious in nature. but make sure animal doesnt aspirate. anaphylactoid reactions are rare but must be
Urinary Track study-kidneys attended immediately. it is necessary to have epinephrine available for immediate admin , when hypotension occurs it can be life threatening and lead to renal failure. contraindication; is dehydration or iodine sensitivity
Urinary Track study-kidneys Procedure: fast for 24 hours, but given water to prevent dehydrations. emenas given when needed at least 2-3 hours before. Ventrodorsal and lateral films taken before exam. films hould be taken with patient in ventrodorsal and
Urinary Track study-kidneys lateral postions immediately after injection and 5 to 15 minutes afterafter injection, follow up studies may be preformed at 20-25 mins after injection
Urinary Bladder study agents- ionic organic iodide are most desirable for retrograde cystography. Nonopaque like air, carbon dioxide and nitrous oxide used in addition to organic iodides for double contrast cystography. Procedure: colon should be cleansed .a Foley
Urinary Bladder study catheter, a tomcat or a soft flexible male catheter is needed. also a syringe and a 3 way valve are needed.2 types cystography performed. positive and double contrast. a positive contrasts is used to detect leaks or rupture of lower urinary
Urinary Bladder study tract after trauma. Ionic organic iodide contrast at concentration of 10% - 15% is injected retrograde into urinary bladder at a dose of 5 - 15 ml/kg of body weight. Double contrast cystography is used to detect all other forms of
Urinary Bladder study urinary bladder disease. a catheter is placed in to urinary bladder and all urine is removed. next, 30-10ml of organic iodide contrast is injected , followed by carbon dioxide or room air at a dose of 50-15 ml/kg of body weight. because of
Urinary Bladder study variability of urinary bladder volume, best to fill bladder to palpable turgidity. lateral and oblique ventrosorsal radiographic views are most helpful
Urethrography - Urethra study ionic organic iodide compounds at 20% concentration. Procedure: a balloon tipped Foley catheter placed in the distal urethra. cuff inflated to prevent leakage . and 10 - 20 ml of contrast hand injected rapidly into the catheter.
Urethrography - Urethra study xrays taken during injection of the last few milliliters. a lateral view and 2 oblique views should be taken during separate injections of contrast material
Spinal cord study Myelography is the contrast examination most used to localize and characterize spinal cord lesions. animal must be anesthetized. Nonionic iodinated contrast medium is injected into the subarachnoid space ( cerebrospinal fluid space) i
Spinal cord study n the cisterna magna( skull C! space) or into the caudal lumbar spine area (L4-L6) Myelography is most commonly preformed before surgery Contrast Agents: 2 nonionic contrast agents iopamidol (Isovue)and iohexol ( Omnipaque)
Spinal cord study the dose medium ranges from 0.25ml/kg for cervical with a cisternal injection to 0.45 ml/kg for cervical eval with a lumbar injection. the concentration with iodine s/b between 240 and 300 mg/ml and injection volume should not exceed 15ml
Spinal cord study contraindications; include infection of the spinal cord and meinges. if treating disease medically rather than surgically, myelography would be contrindicated.
Spinal cord study Procedure; survey films s/b taken first. site of injection s/b aseptically prepared. spinal needles of 20-22 gauge and 3.75-8.75 cm s/b available due to different sized animals. Carefully
Spinal cord study collmated films are taken ventrodorsal and lateral positions immediately after injection
Positioning is essential to obtain diagnostic radiographs. To achieve proper positioning 2 views are right angles are necessary to obtain a diagnostic study. exceptions to this rule are thoracic and spinal exams in horses, or traumatized or debilitated
Positioning animals when only laterals view can be taken without causing undue stress .Also important is centering the primary beam on the lesion itself, when known. important in Orthopedic cases. ex: a fracture healing may look different when the xray beam
Positioning is centered over the fracture line as opposed to a short distance away.
Ultrasound- tissue interaction as sound wave proceed through the body, its progressively attenuated or weakened. attenuation limits the depth of penetration of the sound wave and therefore limits the depth of structures that can be effectively imaged. the ultrasound beam is attenuated
Ultrasound- tissue interaction by absorption , reflection, scattering, refraction and diffraction. Reflection is a redirection of the sound beam back to the transducer and is the basis for diagnostic image. Absorption is sound energy converted to heat within the tissues.
Ultrasound- tissue interaction Scattering is the intertissue micoreflection of sound, which is responsible for much of the echo texture of various organs. Refraction and diffraction are the result of bending of the sound beam as it crosses areas of differing tissue densities.
Ultrasound- tissue interaction Refraction attenuation is important in the generation of several ultrasound artifacts. sound reflection of echo production forms the basis of the ultrasound image. and echo is produced whenever the ultrasound beam crosses an acoustic interface.
Ultrasound- tissue interaction acoustic interface is the boundary between 2 tissues of differing acoustic impedances or Z. Acoustic impedance(Z)= Density(P) x speed of sound trasmission (C), or Z=PxC
Ultrasound- tissue interaction speed of sound is in soft tissue is 1540m/sec, then the main factor that influences acoustic impedance is the density or composition of tissue. thus the more different 2 tissues are the greater will be the echo reflection between them.
Ultrasound- tissue interaction so homogeneous populations of cells (lymphomas, lymph nodes, regenerative liver modules) produce few echos and are generally hypoechoic( darker) if the interface difference is small only a small % of sound will be reflected. if it is large,
Ultrasound- tissue interaction a large portion of sound will be reflected. most soft tissue have a Z, or acoustic impedance withing 1% to 2% of the liver. some interface and % reflections : at/muscle=0.94%, fat/bone=49.00% and tissue/air=100.00% so the acoustic
Ultrasound- tissue interaction impedance between fat and muscle is low and the impedance between fat and bone and between soft tissue and air is high. this is why ultrasound cannot be used to image through bone or gas. too much of the sound beam is reflected back from
Ultrasound- tissue interaction bone and gas interface, because the large change in tissue density.
patient preparation for ultrasound 100% of sound is reflected back when the beam intersects with air. hair traps air, and thus insulates the animal, but if one tries to pass an ultrasound beam through hair , most of the beam is reflected back before it even enters the animal.
patient preparation for ultrasound so a close shave and removal of dirt and scales will improve the image, also a generous volume of ultrasound gel is beneficial for displacing air and coupling the transducer to the skin
patient preparation for ultrasound Small animals are placed in a padded V trough table on their backs or lateral recumbency for abdominal exams, and in lateral or sternal recumbency for cardiac exams. small animals tolerate ultrsould exams well. a special cardiac table
patient preparation for ultrasound with small holes helps echocardiography. large animals are done in the standing tranquilized animal.
Ultrasound display modes A-mode A-mode or amplitude mode, displays returning echos as spikes from a baseline. echo intensity is displayed by the height of the spike. A mode is used in ophthalmology and have little value in vet practice.
Ultrasound display modes B-mode B-mode or brightness mode forms the basis for 2 dimensional imaging.return echos are displayed as dots on the image screen. the brightness of the dots is a function of the strength of the returning echo. the placement of the dot is a function of
Ultrasound display modes B-mode the time it took for the dot to return to the transducer. the cross sectional image is formed through data storage. sound beam is automatically swept across the patient while the transducer is held steady and is moved slowly over the area of interest.
Ultrasound display modes- B mode real time Rapid collection of images is called real time, this permits direct observation of moving structures like a beating heart, movement of a puppy in pregnant mother. B mode with real time equipment , images are displayed in gray scale. Gray
Ultrasound display modes- B mode real time scale is a technique in which various echo strengths are displayed in numerous shades of gray from black to white, similar to a black and white TV.
Ultrasound display modes M-mode time motion (TM) produced by passing a narrow sound beam across a body part. each echo interface is presented as a dot. the motion of the body part is displayd by sweeping the image across the screen or image recorder. M-mode can be thought of as a thin
Ultrasound display modes M-mode time motion (TM) sector of B-mode display as a function of time. M-mode is used primarily for echocardiography ( ultrasonic exam of the heart) ideal equipment for vet practice is a real time B-mode scanner with an M-mode capability.
Selection of transducers( wand)- linear aray critical, the traducers vary in size, sype, style, shape and frequency. Linear array transducers are made with several piezoelectric crystals stacked side by side. crystals are fired in rapid sequence to produce a rectangular cross section image.
Selection of transducers( wand)- linear aray difficult to use these transducer for intercostal cardiac studies and for subcostal studies in cranioabdominal area in small animals. linear transducers are used primarily for transrectal reproductive exams in cattle and horses.
Selection of transducers( wand)- linear aray small foot print convex array transducers are used for small animal
Selection of transducers( wand) Use a transducer with the highest possible frequency to maximize resolution while still allowing penetration to the needed depth.
Frequency of the transducer The higher the frequency of the transducer, the shorter the sound wavelength and the better the resolution, however, as the frequency increases, the depth of sound beam penetration decreases.
Frequency of the transducer the abdominal ultrasonography in small dogs 15kg or less, and cats a 7.5 MHz transducer is ideal. for medium size to large dogs, a 5 MHz transducer works well.
Time gain compensation (TGC) contol the echoes coming from acoustic interfaces close to the transducer are stronger than those returning from farther away from the transducer. TCG amplification compensates for progressive attenuation of the ultrasound beam with increasing depth.
Time gain compensation (TGC) contol TGC is operator dependent, and is set for the best looking uniform image. the controls consists of a series of slide pods on the front of the machine. top pod is the near field of the image and the lowest pod is far field or bottom of the image
The ultrasound image is a thin cross sectional slice through the body in a new or different orientation. use standard image orientation, which places the head or the front of the animal on the left in sagittal
The ultrasound image or longitudinal view, animals right on the left of the screen on the transverse or axial view
Ultrasound terminology Echogenicity-refers to the strength or amplitude of the returning echoes. a structure that is soneodense or echogenic ( bright) produces echoes.
Ultrasound terminology Anechoic or sonolucent ( dark) produces few or no echoes.
Ultrasound terminology Hyperchoic ( brighter than) if it produces more echoes thatn adjacent structures.
Ultrasound terminology Hypoechoic ( darker than) if it produces few echoes than the surrounding structures.
Ultrasound terminology isoechoic ( same as) structure has a level of echogenicity similar to that of adjacent structures.
Ultrasound terminology REMEMBER that echogenicity is a relative term, any structure can be make bright by adjusting the machine control settings. compare organs at the same depth and control setting to prevent misinterpretation of relative echogenicities
Ultrasound aritfacts most fail to take time to understand artifacts. ignored because artifacts do not contribute to useful image information. NOT true they provide accurate clues to what makes up the ultrasound image
Reverberation artifact- dirty shadowing or comet tails occurs when the ultrasound beam hits gas or air. because of the large drop in acoustic impedance ( softer tissue/air interface) the entire ultrasound beam is reflected back. a portion bounces off transducer and reenters the patient. It hits
Reverberation artifact- dirty shadowing or comet tails the air a second time and the same thing happens again. this occurs repeatedly and appears on the screen as a set of bright parallel lines that re the same distance from each other.
Reverberation artifact- dirty shadowing or comet tails each parallel line represents the distance between the transducer and the gas interface.
Shadowing occurs because of inadequate sound beam penetration through a highly reflective or sound absorptive substance. acoustic shadowing is an area of darkness or hypoechogenicity that occurs deep to dense material. like bone, calcium, or calculi.
Shadowing Small objects cast an acoustic shadow only if the are within the focal zone or narrow portion of the ultrasound beam.
Acoustic enhancement or through transmission if the beam passes through an area with few tissue interfaces ( low attenuation region) the emerging beam will have greater intensity that would be expected and will be brighter or more echogenic distal to the nonattenuating structure.
Acoustic enhancement or through transmission EX; normal gallbladder surrounded by hepatic parenchyma. liver tissue distal or deep to the gallbladder appears brighter than adjacent hepatic tissue. this artifact is seen deep to fluid filled structures .
Refraction or edge artifact refraction is a hypoechoic band or stripe at the margin of a curved structure caused by refraction of bending of the sound beam. the sound beam is deflected from its true path and never returns with an effect similar to shadowing. and edge artifact is
Refraction or edge artifact helpful in identifying smooth round structures like early pregnancy vesicles.
Mirror image artifact the ultrasound machine places an image on the viewing screen as a function of the time it took the echo to return. if the sound wave reverberates within a highly echogenic
Mirror image artifact structure before returning to the transducer, the image will be duplicated on the screen distal to the original image. most common is ad duplication of the gallbladder in mirror image o the other side of the diaphragm
Slice thickness artifact if the width of the beam cuts through the edge of a cystic structure and solid tissue, the solid tissue may look as if its layered within the cyst. this artifact is responsible for erroneous appearance of debris within the urinary bladder, gallbladder
Slice thickness artifact the erroneous appearance is the result of volume averaging of tissue by the ultrasound machine
the ultrasound examination requires at least 20-30 minutes. if the answer is quick ( pregnant or hay pyometra) the exam is shorter. ultrasound is used for diagnosis of abdominal disease, a completed exam should be performed every time. it is important to have
the ultrasound examination thorough understanding of various abdominal organs before trying to identify abnormalities associated with disease. remember that echogenicity is a relative term one must compare organs at similar control settings and
the ultrasound examination similar depths to avoid misinterpretation
Ranking from least to most echogenic Renal medulla ( least) liver, renal cortex, spleen, prostate renal sinus fat ( most echogenic)
Nuclear medicine for vets currently vet therapeutic nuclear medicine involves the administration of radioactive iodine( 131 I) for the treatment of hyperthyroidism and thyroid tumors. it doesn't generate visual images, but detects physiologic, pharmacological and kinetic
Nuclear medicine for vets data from the patient in image or numeric data form. common use is for bone scanning for detection of tumor metastasis to bone. scanning for pulmonary embolism. renal scanning for kidney perfusion, thyroid scanning. also hepatobiliary
Nuclear medicine for vets scanning, brain scanning, labeled white blood cell scanning for detection of occult infection, lymphoscintigraphy, nuclear angiography.
Nuclear medicine for vets agent used radionuclide is technetium 99m. ( 99mTc) available from a disposable technetium generator. administered in ionic form as 99mTcO4 (pertechnetate) or is bound to a specific organ localizing pharmaceutical agent before given
electromagnetic radiation has a 6 hour physical half life and emits a 140-KeV gamma ray, which is appropriate for most imaging studies. Common route of administration is IV, latex examination gloves s/b worn
electromagnetic radiation and careful injection technique should be used to ensure that the entire dose is delivered IV not perivascularly. Technetium routes of excretion is urine and lesser in feces. animals should be separated in restricted area, stool and urine carefully
electromagnetic radiation collected and held for decay until levels are below exempt quantities.
electromagnetic radiation diagnostic nuclear med involves admin of radionuclides and detection of the electromagnetic radiation emitted from the animal with a gamma scintillation camera. radionuclides are atoms with unstable nucleus by spontaneous emission of
electromagnetic radiation electromagnetic radiation. electromagnetic radiation that is of nuclear origin is called gamma rays.
Computed Tomography CT scan is obtained by passing a thin xray beam transaxially through the patient,measuring the xray attenuation at multiple sites in a thin slice of the patients anatomy. the computer then reconstructs the transmitted data into a cross sectional image on monitor.
Computed Tomography CT scan PACs( picture archival computing) images are in digital format and are stored in PACs, they can be printed out on film for storage using a dry laser printer. advantage of Ct over common xrays: improved radiographic contrast, spatial
Computed Tomography CT scan resolution, and cross sectional anatomic presentation, all of which eliminate the problem of superimposition of structures. as occurs with radiography
Computed Tomography CT scan Most common use is for head and spinal exams for neurologic disease and radiation treatment planning. Allows vets noninvasive look inside the patients skull. patient placed in ventrodorsal or dorsoventral position on long narrow table. patient moves
Computed Tomography CT scan thru the circular gantry that houses the xray tube and detectors. during each step the Ct scanner obtains a single cross sectional slice of data Modern scanners have a helical scan mode , where the xray tube turns 360 degrees around patient as the bed
Computed Tomography CT scan moves thru the gantry. the helical is faster, so they are excellent for regions like thorax , patient must be heavily sedated to prevent any motion. usually taken with contrast or without. urographic contrast admin dose of 800 mg of iodine per kilo
Magnetic Resonance Imaging MRI similar to CT but MRI does not use ionizing radiation to create the image, instead uses a radio wave signal from tissue in which hydrogen nuclei have been disturbed by a characteristic radiofrequency pulse. it is better than Ct in resolution ,
Magnetic Resonance Imaging MRI anatomic definition and sensitivity to tissue composition difference. better for brain and spinal cord images. disadvantage is it takes much longer time to scan than a CT
Magnetic Resonance Imaging MRI 2 types low field strength and high field strength Low field strength magnets are 0.4 T (tesla) or less. high field strength magnets are 0.6 T and above. typical superconducting magnet has a field strength of 1 or 1.5 T. Safety concerns of MRIs, they have strong magnetic fields
Magnetic Resonance Imaging MRI 2 types low field strength and high field strength and high magnetic field in an MRI unit is always on. and anything made of ferromagnetic metal in or around the magnet will rapidly and forcefully pull these objects to the magnet. like gas anesthetic machine. oxygen tanks, IV poles,
Magnetic Resonance Imaging MRI 2 types low field strength and high field strength clipboards, ink pens, leashes, collars, beepers. plug ears for protection because of the noise and maintain sedation. scan takes 45-60 mins, so animals that cannot stand deep injectable general anesthetic are not good candidates.
Magnetic Resonance Imaging MRI 2 types low field strength and high field strength contrast solution is gadolinium pentetic acid, Organic iodide will not work in MRI.
Created by: Trisha Fravel
 

 



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