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Radiology Test 1
| Question | Answer |
|---|---|
| proton is | mass and has positive 1 charge |
| neutron is | no charge has mass |
| electron has | smaller, negative 1 charge, has mass |
| what is binding energy? | the amount of energy required to remove an electron from a given shell must exceed the electrostatic force of attraction between it and the nucleus |
| which shell would have the greatest binding energy? | K because it is closest to the nucleus |
| what is an ion? | charged particle either positive or negative |
| what is an ion pair? | positive ion or negative ion |
| atom minus and electron would have what charge | positive ion |
| a free electron would have what charge | negative ion |
| an atom plus an electron would have what charge? | negative ion |
| ionization is... | process by which an electrically neutral atom loses or gains an electron and becomes electrically unbalanced the result of ionization is an ion pair |
| ionizing radiation is... | capable of producing ions by removing or adding an electron to an atom such as X-rays |
| radiation definition is | transmission of energy through space or matter |
| what are the two forms of radiation? | particulate radiation electromagnetic radiation |
| what is particulate radiation? | particles have mass and energy particles can be positive, negative, or neutral particles are moving at high velocity |
| what are some examples of particulate radiation? | alpha particles beta particles cathode rays |
| what is electromagnetic radiation? | has neither mass nor charge |
| what are some examples of electromagnetic radiation | gamma rays, x-rays, ultraviolet rays, visible light, infrared radiation (heat), microwaves, radio waves |
| what are types of electromagnetic radiation? | divided by energy: non-ionizing radiation and ionizing radiation |
| ionizing radiation is | has enough energy to remove an orbital electron from an atom |
| what are ionizing rays? | X-rays, ultraviolet, cosmic rays, gamma rays |
| what are the two theories that explain electromagnetic radiation? | wave theory particle or quantum theory |
| wave theory is what? | radiation is propagated in the form of waves consisting of electrical and magnetic fields oriented in planes at right angles to one another oscillating perpendicular to the direction of motion |
| what is wavelength? | the distance from crest to crest or valley to valley or between points on consecutive waves |
| what is frequency? | the number of waves passing a point in a unit of time |
| velocity = | wavelength times frequency |
| short wavelength has... | high frequency |
| long wavelength has... | low frequency |
| what is quantum theory | radiation is depicted as small bundles of energy called photons each photon travels at the speed of light and contains a specific amount of energy |
| SHH | short wavelength, high frequency, high energy |
| LLL | long wavelength, low frequency, low energy |
| the X-ray tube is made up of | cathode anode |
| cathode is... | negative |
| anode is... | positive |
| power supply is made up of | tube current and tube voltage |
| cathode is made up of | tungsten filament and molybdenum focusing cup |
| what does the tungsten filament do? | source of electrons heat releases electrons |
| what does the molybdenum focusing cup do? | concave reflector that focuses the electrons it is not made of tungsten |
| cathode overall does what | generates electrons, production of high speed electrons focusing electrons stopping of high speed electrons at the target |
| anode is composed of what? | tungsten target copper stem |
| why do we use tungsten on the tungsten target? | high atomic number, high melting point, high thermal conductivity low vapor pressure |
| what does the tungsten target do | converts the kinetic energy of the electrons from the filament into x-ray photons |
| where are electrons generated | anode tungsten target focal spot of anode tungsten target |
| what does the focal spot do? | area on the target to which the focusing cup directs the electrons from the filament place that generates X-rays |
| the smaller the focal spot | the sharpness of image increases the heat generated per unit increases |
| actual focal spot sits about how many degrees off target | 20 degrees |
| what would you like to see for an x-ray machine in regards to actual and effective focal spot? | smaller effective focal spot for increase in sharpness and image larger actual focal spot for heat dissipation |
| what does the copper stem do? | good thermal conductor, dissipates heat from the tungsten |
| the glass envelope or tube does what? | provides a vacuum environment withstands tremendous heat |
| what does the x-ray tube window do? | allows the maximum emission of x-rays and minimum absorption by the glass |
| what does oil bath in older x-ray machines do? | electrical insulator, thermal cushion disperse heat |
| what is the protective housing in x-ray machines | lead lined metal casing provides mechanical support prevents excessive radiation exposure and electrical shock |
| what does the aluminum filter do in x-rays? | remove low energy photons |
| what does a collimator do? | limits x-rays to patient (7 cm) restrain size of x-rays |
| low voltage does what for x-ray machines | from the cathode side, provides current and generate heat |
| high voltage does what for x-ray machines | anode and cathode potential controls potential between them and how fast electrons travel |
| direct current is what? | electrons flow in one direction only power supply by battery constant current and uniform spectrum |
| what is alternating current? | electrons flow in alternating directions 60 cycles |
| what is rectification? | process of converting an alternating current voltage into a direct current voltage anode negative, cathode positive (NO CHARGE) |
| milliaperage (mA) is... | low voltage controls the temperature of the tungsten filament and thus how many electrons are available |
| kilovoltage (kVp) is... | high voltage, controls the difference between cathode and anode side |
| what does the timer do on the x-ray machine? | determines the length of time electrons will flow from the cathode to the anode and thus the number of x-rays produced |
| the kinetic energy of electrons is converted to... | X-rays (1%) thermal radiation (99%) |
| what are examples of X-ray radiation | bremsstrahlung radiation characteristic radiation |
| Bremsstrahlung Radiation direct hit what happens? | electron from cathode strokes tungsten filament on anode side hits nucleus and releases bremsstrahlung radiation a photon of maximal energy is released |
| Bremsstrahlung Radiation near miss what happens? | electron from cathode side hits tungsten filament on anode side it nearly misses the nucleus but has an altered path kinetic energy is released and converted to low energy |
| what is the primary source of radiation in an x-ray tube? | bremsstrahlung radiation |
| what is characteristic radiation | radiation originating in ana tom following the removal of an electron from shell |
| what happens during characteristic radiation | high energy electron from the filament displaces an electron from a shell of tungsten (ionization) higher energy electron in an outer shell of tungsten atom fills vacancy |
| what produces monochromatic radiation? | characteristic radiation |
| what produces polychromatic radiation? | bremsstrahlung radiation |
| what is quantity of X-ray beam entail? | the number of photons generated |
| what dictates high quality and low quantity? | more photons, high quantity less photons, low quantity |
| what is quality of X-ray beam entail? | the mean energy of photons generated the maximal energy of photons generated Penetrating power the the beam |
| what dictates high quality and low quality? | high quality has enough energy to penetrate long distance through matter low quality has short distance and stop inside tissue and do not go through patient |
| what is the major factors affecting X-ray beam quantity | Time, milliamperage, kilovoltage, filtration |
| what are the major factors affecting X-ray beam quality | kilovoltage and filtration |
| increased photons (higher quality) = | higher quality |
| increased time does what to quantity? | increased quantity more photons |
| what does milliamperage (mA) control? | controls the temperature on the cathode side the higher the temperature the more photons |
| increase mA will do what to quantity? | increase quantity |
| what does kilovoltage affect? | quantity and quality |
| Increased kVp will do what to quantity and quality | increase quality increase quantity |
| what is filtration | process of selectively removing x-rays from the beam removes low energy or non-penetrating X-rays |
| what does filtration affect? | quantity and quality |
| increased filtration does what to quantity and quality? | increased quality but decreases quantity |
| what is the regulation for x-rays for equal to or less than 70 kVp | greater than or equal to 1.5 mm aluminum |
| what is the regulation for x-rays for greater than 70 kVp | greater than or equal to 2.5 mm aluminum |
| what is collimation? | the process of restricting the size and shape of the x-ray beam |
| what are the federal regulations for the collimation | less than or equal to 2.75 inches less than or equal to 7 centimeters |
| what is the basic idea of inverse square law? | higher intensity the closer to the source lower the intensity further away from the source |
| coherent or classic scattering is... | x-rays are deposited on the patient low energy photon in outer shell takes get bounced out and receives energy of the incident photon (no loss in energy) |
| coherent or classic scattering affect on patient and film... | no significant effect to patient or film |
| what is the major portion of radiation interactions | compton scattering |
| what is compton scattering | incident photon interacts with a loosely bound outer shell electron and knocks it out of orbit into recoil electron as binding energy is overcome |
| what are the patient indications for compton scattering | good for patient but produces film fog energy isn't deposited on patient |
| what is photoelectric absorption? | an incident photon interacts with an inner shell electron, binding energy is overcome and photoelectron is produced when removing |
| what is the indications for the patient and film for photoelectric absorption? | produce radiation inside patient's body produces characteristic radiation, but inside patient's body high quality x-rays are produced (no scatter) |
| coherent scattering makes up what percentage? | less than 10% |
| compton scattering makes up about what percentage? | 60% |
| photoeletric absorption makes up about what percentage | 30% |
| no interaction makes up about what percentage | less than 10% |
| beam attenuation is... | the intensity of an x-ray beam is reduced by interaction with the matter it encounters |
| what is a half value layer? | thickness of this material that is required to reduce the x-ray intensity to one half of its original value |
| beam attenuation is dependent on | thickness of the absorber mass of the absorber energy of the beam |
| thicker the tissue does what to beam attenuation? | less x-ray penetration more x-rays absorbed by material (lighter film) |
| the higher the density of the object on beam attenuation | more photons are absorbed and less x-rays will be transferred to film |
| which type of energy beam (low or high) are much more likely to be absorbed? | low energy photons are much more likely to be absorbed than high energy photons |
| as an x-ray beam passes through matter...the intensity of beam does what | decreases but the mean energy of the resultant beam increases |
| 1 R (roentgen) is how many mR? | 1,000 mR |
| 1 gray is how many rad? | 100 rad |
| 1 sievert (Sv) is how many grays? | 1 gray diagnostic x-ray examinations |
| 1 sievert equals how many rem? | 100 rem |
| what is dosimetry? | determining the quantity of radiation exposure or dose |
| what is exposure? | measure of radiation quantity the capacity of radiation to ionize the air under standard conditions of temperature and pressure |
| what is absorbed dose? | measure of the energy absorbed by any type of ionizing radiation per unit mass of any type of matter |
| what is equivalent dose? | used to compare the biologic effect of different types of radiation on a tissue organ |
| what is density? | overall degree of darkening of an exposed and processed radiograph |
| what is radiolucent | dark area in the radiographic image, resulting from more exposure of the film by radiation passing through the less dense anatomic structure |
| what is radiopaque? | light area in the radiograph image resulting from less exposure of the film by radiation being absorbed by the dense anatomic structure |
| metals show up as what on x-rays? | white or radiopaque |
| bone shows up as what on x-rays? | light area |
| muscle shows up as what on x-rays | dark gray |
| air shows up as what on x-rays? | black or radiolucent |
| what is the major control image density? | mA or milliaperage-second |
| what are the factors that affect image density? | kVp, collimation, filtration, patient factors, focal spot to film distance |
| increasing the mA will do what to the density? | increase density (DARKER image) more electrons reach the anode side and generate more x-ray photons |
| high contract is what kind of gray scale? | short gray scale reduced range of grays between the black area and white areas in a radiographic image |
| low contrast is what kind of gray scale? | long gray scale increased range of grays between the black areas and a white areas in a radiographic image |
| 40 kVp will have what kind of contrast? | high contrast short gray scale |
| 100 Kvp will have what kind of contrast? | low contrast long gray scale |
| what is the major factor affecting image contrast? | Kilovoltage (kVp) |
| increase in kVp will do what do contrast? | decrease the contrast |
| increase in collimation will do what to density? | decrease density |
| increase in collimation will do what to contrast? | increase contrast |
| increase in mA will do what do the image | increased density and darker image more electrons are boiled off and more hit the film because more photons are generated |
| increase in time will do what to density? | increase density and darker image more photons |
| increase in mA does what to density and contrast? | increased density, darker image no change in contrast |
| increase in kVp does what to density and contrast? | increase density, darker image decrease in contrast, low contrast |
| increase focal spot to film distance does what to density and what to contrast? | decreases density, image is lighter no change in contrast |
| increased collimation does what to density and what to contrast? | decreased density, image is lighter increased contrast, high contrast |
| increased filtration does what to density and what to contrast? | decrease in density, image is lighter decrease in contrast, low contrast |
| increased thickness in patient will do what to density? | decrease density and a lighter image |
| photons come from which side? | anode |
| electrons come from which side? | cathode |
| what is the measurement of the capacity of radiation to ionize air under standard conditions of temperature and pressure? | Roentgen (mR) coulombs per kilogram |
| what is the measure of the energy absorbed by any type of ionizing radiation per unit mass of any type of matter? | gray rad |
| what is the measure to compare the biological effects of different types of radiation on a tissue or organ? | sievert rem |
| what is a penumbra? | photons originating at different places on the focal spot resulting in a penumbra or zone of unsharpness on the radiograph |
| what is image sharpness? | measures how well a boundary between two areas of differing radio density is revealed |
| what is image resolution? | measures how well a radiograph is able to reveal small objects that are lose together |
| what are the factors that affect image definition | focal spot size focal spot to object distance object to film distance |
| the smaller the focal spot size, what happens to penumbra, image sharpness and resolution? | smaller the penumbra, the higher the image sharpness and the higher the resolution |
| the smaller the target angle... what happens to penumbra and sharpness? | higher the sharpness and the smaller the penumbra |
| for focal spot size, the penumbra is... | directly related to the size of the effective focal spot |
| what is principle 1 for focal spot size? | use as small an effective focal spot as practice need to be large enough to disperse heat |
| focal spot to object distance, the penumbra is... | penumbra is inversely related to the focal spot to object distance |
| what is principle 2 for focal spot to object distance? | increase the distance between the focal spot and the object by sing a long, open-ended cylinder |
| for object to film distance, penumbra is... | directly related to the object to film distance |
| what is principle 3 for focal object to film distance? | decrease the distance between the object and the film |
| what are the factors that influence image definition? | kVp and mA motion |
| kVp does what do image definition? kVp increases... | the size of the focal spot will decrease slightly with an increase in kVp beam appears narrow when kVp is increases and the sharpness of the image increases |
| what does mA do to image definition? mA increases... | the size of the focal spot will increase slightly with an increase in mA temperature increases, more electrons, spread out towards anode side |
| magnification is... | refers to an increase in size of the radiographic image as compared with the actual size of the object |
| what are the control factors for magnification? | focal spot to film distance object to film distance |
| analog is... | continuous values smooth transition |
| digital is... | discrete values discrete steps, steps are numerous and small so looks small |
| what is digital radiography | the image is recorded electronically rather than on film |
| what is direct imagining? | intra-oral receptor inside the mouth making a radiograph |
| what is still required for digital radiography? | x-ray generator |
| what are the three types of digital radiography | CCD, CMOS, PSP |
| how does film work? | put sensor in and expose to radiation image is recorded on film film is put into a processor and proceed and same film comes out with image |
| How do solid film work? | put senor in and expose to radiation image captured on image receptor and transferred to computer the image is recorded digitally |
| how do the solid phosphor plates work? | put sensor in and expose to radiation take film out and put into laser reader image is erased on plate and transferred to CPU |
| hardware for digital radiography is | image receptor and computer equipment |
| software for digital radiography is | program used to manipulate and display images |
| how is the image created for CCD and CMOS? | image is created when the x-ray photon interacts with a silicon atom |
| CCD darker areas are | where lots of electrons are trapped in electron wells |
| CCD light areas are | where less or no electrons are trapped in electron wells |
| scintillation is | extra layer added to make the sensor more sensitive, less radiation is needed to make the image but the sensor becomes larger |
| how is CMOS different than CCD | CMOS had a microprocessor in the electron wells so when photons interact with silicon the electrons are counted and information is received a bit faster |
| spatial resolution is a measure of | fine detail |
| all sensors have a higher spatial resolution than | storage phosphor |
| CMOS and CCD have what kind of spatial resolution? | same spatial resolution |
| film has what kind of spatial resolution when compared to CCD | higher or equal spatial resolution to CCD |
| PSP has what kind of latitude when compared to CCD | higher latitude than CCD |
| CMOS and film have what kind of latitude | same latitude |
| when an x-ray sensor is fast, what does that mean | how much radiation exposure is required to get a diagnostic image |
| cathode ray tube (CRT) is best at... | shades of gray wider viewing angle |
| thin film transistor (TFT) is best at... | superior in color fixed resolution narrower range of gray shades higher contrast |
| lossless storage is... | reversible: no data is lost lower compression ratios |
| lossy storage is... | irreversible: data is lost higher compression ratios |
| CCD and CMOS summary | usually wired inflexible and thicker limited area 1 step procedure |
| PSP summary | no wires some flexibility larger active area 2 step process |
| which of the following is NOT considered to be "particulate" radiation | X-rays |
| long wavelength x radiation has _____ | low energy and low frequency |
| in the Bohr atomic model, what is the designation of the inner electron shell? | K |
| to ionize an atom, the incoming x-ray photon must have enough energy to exceed the ____ energy of the electron that it ejects | binding |
| which of the following is NOT a characteristic of X radiation | travels at a variety of speeds |
| x rays differ from visible light in that they.... | have higher energy than visible light |
| the target of the x-ray tube is typically made of | tungsten |
| the filament of an x-ray tube is heated by the _____ voltage circuit which contains a _____ transformer | low voltage step-down |
| the timer on a self rectified dental -ray unit is set at 30 impulses that is the equivalent of... | 0.50 |
| which of the following is a part of the anode in an x-ray tube | copper stem |
| which of the following controls the energy of the x-ray beam | kVp |
| which of the following controls the quantity of photons in the x-ray beam | kVp exposure time milliamperage |
| the line focus principle has to do with the... | size of the focusing cup |
| filtration of the x-ray beam removes... | long wavelength photons |
| if a high speed electron makes a direct hit on the nucleus of the target atom, what type of radiation is produced? | bremsstrahlung |
| the oil surrounding the glass x-ray tube is considered to be part of the ____ filtration of the beam | inherent |
| the half value layer of an x-ray beam is used to describe the ____ of the the beam | quality |
| what effect will increasing the kVp have on an x-ray beam | number of photons will be increased the mean energy of the beam will be increased the maximum energy of the beam will be increased |
| the first step in characteristic radiation production is when an incoming high energy electron collides with a ____ of the target atom creating a vacancy | electron |
| the majority of the x-ray beam spectrum is ____ radiation | bremsstrahlung |
| a low energy photon interacts with an outer shell electron and ejects it. what type of interaction occurred? | compton scattering |
| a recoil electron is NOT part of which interaction? | coherent (classical scattering) |
| what unit is used to measure radiation exposure in air | coulombs per kilogram |
| an x-ray photon passes through an object without interacting with any atoms when it exists the object, it is referred as ____ radiation | remnant |
| the overall degree of darkening on a processed x-ray film is called ___image | density |
| a film comes out of the processor and it is too light because the patient is very large. which of the following techniques changes would increase the radiographic density | increase the exposure time |
| metal object (like amalgam) absorb virtually all of the x-ray photons that they are exposed to. thus they appear ____ on the processed x-ray film | radiopaque |
| before making a radiograph, you increase the kVp on an x-ray machine and keep all other technique factors. this will make the image on the processed film have.... | less contrast and greater density |
| which of the following decreases penumbra? | decreasing effective focal spot size |
| the x-ray beam is perpendicular to the film, but not the object, which of the following describes the results | foreshortening |
| the image of the edge of an object typically appears slightly blurred, this blurred zone is called... | penumbra |
| as the object to film distance increases what is the effect on the image? | increased magnification |
| the ability of a radiograph to distinguish small structures or objects that are close together is called | resolution |
| a large number of shades of gray or long gray scale implies | low contrast |
| when the bombarding electron stream interacts with the target, the majority of the kinetic energy of the electrons is converted to | heat |
| as the filament of the x-ray tube is heat _____ are emitted or bubbled off forming a cloud. this process is thermionic emission | electrons |
| the exposure factor that is the primary control for radiographic contrast is... | voltage |
| soft tissue structures such as the tongue are said to have | low subject contrast and low subject density |
| which of the following is NOT found in dental x-ray film packets | intensifying screen |
| according to the wave theory of electromagnetic radiation | frequency and wavelength are inversely related |
| gamma rays originate... | in the nucleus of radioactive atoms |
| ionization occurs when | an electrically neutral atom loses and electrons |
| particulate radiation consists of | consists of atomic nuclei or subatomic particles moving at high velocities |
| the milliamperage control of the x-ray generating unit regulates the... | availability of electrons for the generation of x-rays |
| in an x-ray tube, the face of the anode is placed at an angle to the electron beam to... | improve radiographic image sharpness and increase the heat capacity of the anode |
| in standard x-ray machines the quality of x-radiation produced during exposure is controlled primarily by the | kVp |
| at diagnostic levels, what percentage of the projectile electrons kinetic energy is converted to x-ray radiation at the anode | less than 1% |
| increasinf the operating kVp of an x-ray machine increases the.... | number and energy of x-ray photons generated |
| the majorityof electromagnetic radiation produced in a dental x-ray tube is... | thermal radiation |
| bremstrahlung radiation is generated as a result of... | interactions between a projectile electron and the nucleus of a target atom |
| what refers to the anode | it serves as an electrical conductor and provides mechanical support for the target |
| which of the following refers to the cathode | consists of a filament and focusing cup |
| which of the following refers to the radiographic tube housing | it prevents excessive radiation exposure |
| the radiation that occurs when an electron moves from an outer orbit to fill a vacancy in an inner orbit is called | characteristic radiation |
| the longer the x-ray wavelength... | the less penetrating the x-ray photos |
| an x-ray beam is heterogeneous or polychromatic because | the potential across the tube changes constantly as the AC voltage caries |
| the reduction in radiation intensity as it passes through material is termed | attenuation |
| the x-ray beam is made more penetrating by... | increasing the kVp |
| if the milliamperage is doubled what must operator do to the exposure time to maintain the intensity of the x-ray beam if all other factors are held constant | reduce exposure time by one half |
| the beam of radiation emitted from the radiographic tube housing consists of... | x-ray photons of many different energies and wavelengths |
| the radiation which produces the diagnostic image consists of | remnant radiation plus scatter radiation |
| remnant radiation is... | a component of an image producing radiation |
| quality of the x-ray beam can be most accurately measured by which of the following | half value layer |
| both milliamperage setting and the exposure time determine the | number of x-rays produced |
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Chobchi
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