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radiologydh
xray DH
| Question | Answer |
|---|---|
| Making radiographs by exposing an image receptor,by film or digital sensor | radiography |
| Study of x-rays and techniques to produce radiographic images | oral radiology |
| An image or picture produced by x-rays a) picture b) radiograph c) total graph d) digital picture | b) radiograph |
| The study of x-radiation a) radiology b) radiography c) roentegen | a) radiology |
| discovered x-rays? a) Francis Mouyen b) H. R. Raper c) W.C. Roentegen | c) W.C. Roentgen |
| wrote the first dental book? a) O. Walkhoff b) W. Roentegen c) H.R. Raper d) W. Coolidge | c) H. R. Raper |
| When were x- rays discovered? | 1895 |
| older term given to x-radiation in honor of discoverer? | roentgen ray |
| Term used by oral health care professionals, more descriptive than x-ray & easier to pronounce | radiograph |
| Introduced Victor CDX shockproof dental x-ray machine | William David Coolidge & General Electric |
| Published "X Light Kills" warning of x-ray dangers | W.H. Rollins |
| Unit capable of exposing entire dentition and surrounding structures on single image | Panoramic radiography "pano" |
| Imaging system that allow for enhanced two and three dimensional images for diagnosis and treatment of dental conditions | digital imaging |
| Method of imaging a single selected plane of tissues, used to assist dentists with complex diagnosis and treatment planning | computed tomography "CT scans" |
| Who exposed prototype of first dental x-ray film | Otto Walkhoff |
| imaging system most likely to become gold standard for imaging certain dental conditions in near future | cone beam volumetric tomography |
| given credit for applying rule of isometry to bisecting technique | A. Cieszynski |
| given credit for developing paralleling technique | Franklin McCormack |
| Currently we know of __________ basic elements | 118 |
| Each element made up of __________ | atoms |
| smallest particles of element, retains properties of element | atom |
| smallest particle of substance, retains properties of substance | molecule |
| __________ have negative charge and constantly in motion orbiting nucleus | electron |
| has positive charge | protons |
| has no charge | neutrons |
| The number of protons in nucleus of an element determines ______________ | atomic number |
| Electrons are maintained in their orbits by positive attraction of the protons, known as ________ | binding energy |
| Atoms that gained or lost electrons are electrically unstable | ions *ion is defined as a charged particle* |
| positively charged atom ion and negatively charged electron ion are called | ion pair |
| Formation of ion pairs | ionization |
| emission and movement of energy through space in form of electromagnetic waves | radiation |
| radiation that produces ions | ionizing radiation |
| process that certain unstable elements undergo spontaneous disintegration, result in new isotope | radio activity |
| Dental x-rays do/do not involve use of radio activity | do not |
| movement of wave like energy through space as combination of electric and magnetic fields | electromagnetic radiation |
| Consists of orderly arrangement of all known radiant energies | electromagnetic spectrum |
| Bundles of energy, travel through space at the speed of light, "bullets of energy" | photons |
| Distance between two similar points on two successive waves | Wave length *measured in angstrom (A) units* |
| Measurement, number of waves that pass given point per unit of time | frequency * measured in hertz (Hz) * |
| speed of wave | velocity |
| Long wave length -low frequency -low energy -less penetrating x-ray | Soft radiation "Grenz rays" |
| Short wave length -high frequency -high energy -more penetrating power | hard radiation |
| X-rays have following properties: | -invisible -travel straight lines -travel speed of light - no mass or weight -have no charge -interact with matter causing ionization -penetrate opaque tissues and structures -affect biological tissue -affect photographic film |
| Dense structures, like bone and enamel appear white or gray on x-ray, this is called | radiopaque * white * |
| Less dense structures, like pulp chamber, muscles and skin appear _____________ | radiolucent * darker/gray * |
| bodies in motion, believed to be | kinetic energy |
| ___________ is produced when bombarding electron from tube filament collides with orbiting K electron of tungsten target | Characteristic radiation |
| Produced when high-speed electrons are stopped or slowed down by tungsten atoms of dental x-ray tube | general/bremsstrahlung |
| beam of x-rays passing through matter, weakened and gradually disappears, disappearance is called | absorption |
| When x-ray passes through atom unchanged, no interaction occurs, this is called | No interaction * 9% in dental radiology * |
| When low energy x-ray passes near atom's outer electron, may be scattered without loss of energy is called | Coherent scattering (unmodified scattering, "Thompson scattering" |
| "All or nothing energy loss" X-ray imparts all energy to an orbital electron of some atom | Photo electric effect |
| Similar to Photoelectric effect, only part of dental x-ray energy is transferred to electron, and new, weaker x-ray is formed and scattered in new direction | Compton effect aka Compton Scattering |
| most widely accepted terms used for radiation units of measurement come from | Systeme Internationale "modern version of metric system" |
| Amount of energy deposited, any form of matter (such as teeth, soft tissues, treatment chair) by any type of radiation (alpha, beta particles, gamma or x-rays) | Absorbed dose |
| Unit for measuring absorbed dose | gray (Gy) or rad |
| Term used for radiation protection purposes to compare biological effects of various types of radiation | dose equivalent |
| unit for measuring, dose equivalent is | sievert (Sv) or rem |
| aid in making more accurate comparisons between different radiographic exposures __________ is used to compare risk of radiation exposure a biological response | effective dose equivalent |
| ionizing radiation, always present in environment | background radiation |
| Contains regulating devices on dental x-ray machine | control panel |
| enables tube head to be positioned on dental x-ray machine | extension arm or bracket |
| contains x-ray tube that x-rays are generated | tube head |
| 5 major controls operated or will be preset on dental x-ray machine | -line switch to electrical outlet -milliampere selector -kilovoltage selector -the timer -exposure button |
| measures amount of current passing through wires of circuit | milliampere (mA selector) |
| determines available number of free electrons at cathode filament, therefore amount of x-rays that will be produced | amperage |
| measures difference in potential or voltage across x-ray tube | kilo volt peak (kVp) selector |
| Determines speed of electrons traveling toward target on anode, the penetrating ability of x-rays produced | kVp |
| Flows continuously in one direction | direct current (DC) |
| "The house hold current" changes direction of flow 60 times per second | AC alternating current |
| Electromagnetic device for changing current coming into dental x-ray machine | transformer |
| decreases voltage from wall outlet to approximately 5v, enough to heat filament & form electron cloud | step-down transformer |
| increases voltage from wall outlet to approximately 60-100 kVp to propel electrons toward target | step-up transformer |
| located in control panel, is voltage compensator that corrects minor fluctuations in current flowing through wires | auto transfomer |
| measurement of number of electrons moving through wire conductor | amperage |
| describes electrical pressure (difference in potential) between two electrical charges | voltage |
| located inside tube head, a glass bulb from where air has been pumped to create vacuum | x-ray tube |
| beam of x-rays, originates at focal spot and emerges through port of tube head | primary beam or useful beam |
| x-ray in center of primary beam | central beam |
| x-ray beam that is composed of variety energy wavelengths | polychromatic |
| What metal is used for target in x-ray tube | tungsten |
| Charged negatively during time that x-ray tube is operating to produce x-rays | cathode |
| describes opening in tube housing, allows primary beam to exit | port |
| removes low-energy, long wavelength energy from beam | filter |
| process of heating cathode wire filament until red hot and electrons boil off | thermionic emission |
| Three basic requirements for acceptable diagnostic radiograph | -must be imaged as close to their natural shapes and sizes as the patient's oral anatomy will permit -area examined must be imaged completely -free of errors and show proper density, contrast, and definition |
| refers to portion of image that is dark or black, permit passage of x-rays with little or no resistance | radiolucent * abscess, soft tissues, air space * |
| refers to portion of image that is light or white, areas are dense and absorb or resist the passage of x-rays | radiopaque * enamel, dentin, bone * |
| degree of darkness or image blackening | density |
| refers to many shades of gray that separate dark and light areas | contrast |
| describes radiograph when density differences between adjacent areas are large -high contrast | short-scale contrast |
| describes radiograph when density differences between adjacent areas are small - low contrast | long-scale contrast |
| refers to detail and clarity of outline of structures shown on radiograph | sharpness/definition |
| partial shadow around objects of interest | penumbra |
| rules for casting a shadow image | 1)small focal spot 2)long target-object distance 3)short object-image receptor distance 4)parallel relationship between object and image receptor 5)perpendicular relationship between the central ray of the x-ray beam & both the object & the image rece |
| to reduce size of penumbra resulting in sharper image and slightly less magnification | small focal spot |
| to reduce penumbra and magnification | long target-object distance |
| to reduce penumbra and magnification | short object-image receptor distance |
| to prevent distortion of image | parallel relationship between object and image receptor |
| to prevent distortion of image | perpendicular relationship between the central ray of the x-ray beam and both the object and the image receptor |
| factors affecting radiographic image | subject kilovoltage peak (kVp) scatter radiation film/digital sensor type exposure processing |
| small focal spot | increase sharpness |
| large focal spot | decrease sharpness |
| long target-image receptor distance | increase image |
| short target-image receptor distance | decrease sharpness |
| underexposed or over exposed radiograph will result in | diminished or poor contrast |
| small part on target where bombarding electrons are converted into x-rays | focal spot |
| when long PID is used, x-rays in center of beam are more parallel, resulting in | less image magnification |
| object-image receptor distance should | be kept to a minimum |
| result of unequal magnification of different parts of same object (image receptor is not parallel to object) | distortion |
| increasing mA, increases (darkens) ___________ of radiograph | density |
| decreasing mA, decreases (lightens) _________ of radiograph | density |
| interval that x-ray machine is fully activated and x-rays are produced | exposure time |
| increase mA, makes image density | darker |
| decrease mA, makes image density | lighter |
| increase time makes image density | darker |
| decrease time, makes image density | lighter |
| increase kVp, makes image density | darker |
| decrease kVp, makes image density | lighter |
| length of target-surface distance depends on length of | position indicating device (PID) |
| quality of radiographic image improves whenever target-image receptor distance is | increased |
| Increasing target-image receptor distance reduces fuzzy outline (penumbra), seen around radiographic images | true |
| positioning image receptor far enough from teeth to enable it to be held parallel and using long 12in PID will increase quality of image definition | true |
| degree of darkening of radiographic image is referred to as | density |
| image contrast, not affected by | milliamperage |
| fuzzy shadow around outline of radiographic image | penumbra |
| distortion results when | object and image receptor are not parallel |
| theory that x-ray photons collide with important cell chemicals and break them apart by ionization, causing critical damage to large molecules | direct theory |
| theory based on assumption that radiation can cause chemical damage to cells by ionizing water within it | indirect theory |
| term used to describe degree of susceptibility of various cells and body tissues to radiation | radiosensitive |
| Which cell is most sensitive to damage from radiation | white blood cells (lymphocytes) |
| all cells of body, except reproductive cells | somatic cells |
| effect that occurs when biological change or damage occurs in irradiated individual, but not passed along to offspring | somatic effect |
| describes changes in hereditary material that do not manifest in irradiated individual, but in future generation | genetic effect |
| genetic cells | eggs and sperm |
| radiation that depends on type, energy, and duration of radiation (greater of dose, more severe probable biological effect | total dose |
| rate which radiation is administered or absorbed is very important in determination of what effects will occur | dose rate |
| various species have wide range of radiosensitivity | variation in species |
| lethal dose (LD) for each species is expressed in statistical terms. For humans LD is | LD 50/30, estimated to be 4.5 gray (Gy) or 450 rad |
| younger, more rapidly dividing cells are more radiosensitive than older, mature cells, so children are more susceptible to injury than adults from an equal dose of radiation | true |
| following initial radiation exposure, and before first detectable effect occurs, a lag time called | latent period |
| following latent period, certain effects can be observed this is called | period of injury |
| following exposure to radiation, some recovery can take place | recovery period |
| certain amount of damage where there is no recovery occurs is called | irreparable injury |
| when biological response is based on probability of occurrence rather than severity of change is called | stochastic effect "all or nothing effect" |
| likelihood of injury or death from some hazard | risk |
| primary cause of biological damage from radiation is | ionization |
| direct injury from radiation occurs when x-ray photons | strike critical cell molecules |
| indirect injury from radiation occurs when x-ray photons | ionize water and form toxins |
| Which cell are most radio resistant | muscle cells |
| dose response curve indicating that any amount of radiation, no matter how small, has potential to cause biological response is called | nonthreshold |
| ALARA | as low as reasonably achievable |
| what is considered short term outcome following radiation exposure | acute radiation syndrome |
| comparisons between dental radiation exposures and natural background exposure | effective dose equivalent |
| controls size and shape of useful beam | collimation |
| collimation reduces | scatter radiation |
| lead apron has to be made of at least | .25mm lead or lead equivalent material |
| minimum total filtration that is required by x-ray machine that can operate in ranges above 70kVp | 2.5 mm of aluminum equivalent |
| annual maximum permissible whole-body dose for oral health care personnel is | 50 mSv |
| annual maximum permissible whole-body dose for the general public is | 5.0 mSv |
| silver halide crystals are sensitive to radiation | true |
| silver halide crystals, when exposed to x-rays, retains the | latent image |
| When radiation reaches emulsion, silver halide crystals are ionized, or separated into silver and bromide and iodide ions that store energy as a | latent image |
| _________ absorbs most radiation | enamel |
| designed for use inside oral cavity | intraoral films |
| _________ used to determine film orientation and used to distinguish between radiographs of patients right and left side | identification dot |
| sizes of intraoral film | 0, 1, 2, 3, 4 |
| images coronal portions of both upper and lower teeth and crestal bone on same film | bitewing radiographs |
| used to record detailed examination of entire tooth, from crown to root rip or apex | periapical radiograph |
| ideal for recording large area of the maxilla, mandible, and floor of mouth | occlusal radiograph |
| designed for outside of mouth | extraoral films |
| large films, classified as screen film | extraoral films |
| screen film means | indirect exposure film |
| provides support for fragile film emulsion | base |
| light and x-ray sensitive | silver halide crystals |
| what is function of lead foil in film packet | absorb backscatter radiation |
| What can be found on back side of intraoral film packet | film speed number of films in packet embossed dot location |
| Which film has greatest sensitivity to radiation a) D- speed b) E- speed c) F- speed | F- speed |
| size #4 intraoral film packet,most likely used to expose | occlusal radiograph |
| What projection will dentist most likely prescribe for evaluation of specific tooth and surrounding structures | periapical radiograph |
| Intensifying screens will | reduce exposure time |
| What is considered to be a screen film | panoramic |
| X-ray films should be stored | away from heat and humidity |
| Role of this solution is to reduce exposed silver halide crystals within film emulsion to black metallic silver | developer solution |
| Processing transforms________ image, which is produced when x-ray photons are absorbed by silver halide crystals in emulsion, into visible, stable image by means of chemicals | latent |
| Basic steps of processing dental x-ray film are | developing rinsing fixing washing drying |
| Removes unexposed and/or undeveloped silver halide crystals from the film emulsion | fixer solution |
| Prevents rapid oxidation of developing agents | preservative |
| Activates developing agents by providing required alkalinity | activator |
| Restrains developing agents from developing unexposed silver halide crystals, which produce film fog | restrainer |
| Slows the rate of oxidation and prevents deterioration of the fixing agent | preservative |
| Shrinks and hardens the gelatin emulsion | hardening agent |
| Stops further development by neutralizing the alkali of the developer | acidifier |
| What is minimum distance from source of light and counter space where film will be handled | 4 -ft |
| When film can be read under white light after 2-3 minutes of fixing is called | wet reading |
| Manual processing can be used to produce a working radiograph without a darkroom in about ______ seconds | 30 |
| Process by which latent image becomes visible | reduction |
| What is correct processing sequence | develop, rinse, fix, wash, dry |
| The basic constituents of developer solution are | developing agent (reducing agent) preservative activator restrainer |
| During which step of the processing procedure are the exposed solver halide crystals reduced to metallic silver | developing |
| Which ingredient removes the unexposed/undeveloped silver halide crystals from the film emulsion | sodium thiosulfate |
| Which ingredient causes emulsion to soften and swell | activator |
| Which ingredient hardens emulsion | potassium alum |
| Chemically, the developer used in automatic processor contains more _______ than developer used for manual processing | hardener |
| Which colors of safelight filters is safe for processing all film speeds | red |
| What is appearance of the radiographic image if film is exposed to safelight too long | fogged |
| A thermometer is used for manual processing to determine temperature of | developing solution |
| What is ideal temperature for processing film manually | 68 F |
| Replenisher is addd to developing solution to compensate for | oxidation loss of volume loss of solution strength |
| Which processing method requires most maintenance & strictest adherence to regular replenishment and cleaning | automatic |
| Discrete units of information that together constitute an image | pixel |
| The discernable separation of closely adjacent image details | spacial resolution |
| Refers to number of paired lines visible in 1mm of an image | line pair |
| Relating to mechanism in which data is represented by continuously variable physical quantities | analog |
| Refers to total number of shades of gray visible in image | gray scale |
| A ______ radiographic image exists as bits of information in computer file | digital |
| The computer converts information into image that appears on computer monitor | true |
| Digital radiography can be used for | to detect caries to monitor an endodontic procedure to detect dental disease |
| When a transparency scanner or digital camera is used to convert an existing film-based radiograph to digital file, process is called | digitization |
| The following are digital image receptors | CCD CMOS PSP |
| Stores x-ray energy until later simulation by a laser beam, reads electric signal and converts it into digital image | PSP (photostimuable phosphor plate) |
| smaller the number of pixels in image the sharper the spatial resolution | true |
| Each pixel stores a number representing different shade of gray | true |
| Digital radiography requires less radiation exposure to produce an image than film based radiography because the | image receptor (CDC or CMOS) is more sensitive to x-rays than film |
| Image receptor is called a | sensor |
| Polyester plate covered with phosphor crystals is called a | photostimuable phosphor (PSP) plate |
| A solid state detector used in digital sensors. Converts x-rays to electrons that are sent to computer via a wire | Charge-coupled device (CCD) |
| A solid state state integrated circuit used in digital radiography as an image receptor in the intraoral sensor | Complementary metal oxide semiconductor (CMOS) |
| Digital imaging sensors that use rare earth phosphor coated plates. When exposed to x-rays, __________ stores the x-ray energy until stimulated by a laser beam to produce a digital image | photostimuable phosphors (PSP) |
| Allows for comparison of digitally stored images to detect changes over time or prior to and after treatment interventions | digital subtraction |
| To prevent transmission of disease among patients | infection control |
| primary purpose of infection control is to | prevent the transmission of infectious diseases |
| microorganism capable of causing disease | pathogen |
| Agent used on living tissues to destroy or stop the growth of bacteria | antiseptic |
| Absence of septic matter or freedom from infection | asepsis |
| Soiling by contact or mixing | contamination |
| Making someone immune to a disease | immunization |
| Suspension of microorganisms that may be capable of causing disease produced during normal breathing and speaking | microbial aerosol |
| Infection or presence of septic matter | sepsis |
| practice of care to protect persons from pathogens spread via blood or any other body fluid, excretion or secretion | standard precautions |
| total destruction of spores and disease-producing microorganisms, accomplished by autoclaving | sterilize |
| Routes of infection are | direct contact with pathogens direct contact with airborne contaminants present in aerosols indirect contact with contaminated objects or instruments |
| For infection to occur, four conditions must be present | 1) a susceptible host 2) a disease causing microorganism 3)sufficient numbers of pathogen to initiate infection 4) an appropriate route (port of entry) to enter host |
| Use of chemical or physical procedure to reduce disease-producing microorganisms to acceptable level on inanimate objects | disinfection |
| Chemical germicides inactivate spores, can be used to disinfect heat sensitive semicritical dental instruments | high level disinfectant |
| Instruments used to penetrate soft tissue or bone | critical instruments |
| Instruments that contact oral mucosa without penetrating soft tissue or bone | semicritical instruments * x-ray image receptor holding devices |
| Clinical contact surfaces are those devices and surfaces of treatment area that may contact intact skin or may become contaminated by microbial aerosols or spatter, but not mucous membranes | noncritical instruments * lead apron, PID, chin rest and head positioner |
| An approach to infection control that states that body fluids (except sweat) of all patients should be treated as if infected is | standard precautions |
| What agency develops and provides recommendations for adoption of infection control guidelines, does not act as enforcer of these guidelines | Centers for Disease Control and Prevention (CDC) |
| Spraying disinfectant directly on which of these should be avoided | x-ray machine exposure switch |
| What should be done with image receptor immediately after removing it from patient's mouth | remove excess saliva with a dry or disinfectant soaked paper towel |
| order of maintaining infection control after radiographic procedure | remove patient treatment gloves remove lead apron put on utility gloves clean and disinfect |
| key to producing quality radiographic images is | gaining patient trust presenting a confident, caring image communicating effectively |
| ability to share in patient's emotions and fellings is called | empathy |
| Refers to relationship between patient and oral health care professional | patient relations |
| Position assumed by body in connection with feeling or mood | attitude |
| Used to communicate with others successfully | interpersonal skills |
| Process by which information is exchanged between two or more patients | communication |
| Effective use of words in ___________ begins with facing patient directly and maintaining eye contact | verbal communication |
| Includes gestures, facial expressions, body movement, and listening | non verbal communication |
| Consists of methods of exposing dental x-ray film, phosphor plates, or digital sensors within oral cavity | intraoral |
| Examination that images coronal portions of teeth and alveolar crests of bone of both the maxilla and mandible on a single radiograph. Good for detecting carries | Bitewing examination |
| Used to image apices of teeth and surrounding bone | periapical examination periapical radiographs |
| Images entire maxillary or mandibular arch | occlusal examination |
| _________ is technique of choice because is more likely to satisfy more of shadow casting requirements | paralleling |
| Technique known as "rule of isometry" | bisecting technique |
| ________ technique is more likely to meet most of shadow casting rules, making technique less likely to produce image distortion | Paralleling technique |
| Full mouth series consists of __________ films | 18 |
| procedure by which tube head and PID are aligned to obtain optimum angle at which radiation is to be directed toward image receptor is called | angulation |
| ____________ is changed by rotating tube head horizontally and vertically | angulation |
| _________ is achieved by directing central rays perpendicularly toward surface of image receptor in horizontal plane | horizontal angulation |
| Achieved by directing central rays perpendicularly toward surface of image receptor in vertical plane | Vertical angulation |
| Vertical angulation is customarily described in | degrees |
| When portion of image is not recorded on radiograph | conecut error |
| Point of entry for central ray should be in middle for image receptor | true |
| Holders designed to position phosphor plate or digital sensor | film holders |
| How many size 2 image receptors are required by most health care practices for exposure of posterior radiographs of full mouth series | 8 |
| Anterior periapical image receptors are placed vertically/horizontally | vertically |
| Posterior periapical image receptors are placed _________ in oral cavity | horizontally |
| Where should embossed identification dot be positioned when taking periapical radiograph | toward the incisal or occlusal edge of the tooth |
| Which setting would PID be pointing to the floor | +20 |
| What is correct seating position for patient during radiographic examination when an image receptor without an external aiming device is used | occlusal plane parallel and midsaggital plane perpendicular to the floor |
| What is best sequencing for exposing full mouth series of periapical radiographs | maxillary anteriors, mandibular anteriors, maxillary posteriors, mandibular posteriors |
| Advantage of using paralleling technique | produces images with minimal dimensional distortion |
| Interproximal space is the | embrasure |
| To compensate for increased object-image receptor distance needed to achieve parallelism, target-image receptor distance should be | increased |
| Important reason for using a holder when utilizing paralleling technique is to stabilize image receptor in a position | parallel to the teeth |
| Film holders designed for use with paralleling technique should have a | long biteblock and L-shaped backing |
| Example of holder that can be used with both paralleling and bisecting techniques | SUPA |
| Directing central rays perpendicular to plane of image receptor and perpendicular to long axes of the teeth describes which step of the paralleling technique | vertical angulation |
| Cutting off root apex portion of image on a periapical radiograph results from | inadequate vertical angulation |
| Results in incisal/occlusal edges being cut off image | excessive vertical angulation |
| The __________ technique satisfies fewer shadow cast principles | bisecting |
| __________ is applied when image receptor is not, or cannot, be placed parallel to long axes of the teeth | bisecting |
| Tooth and film should be as close as possible | bisecting technique |
| Imaginary line between two lines | bisector |
| Image receptor holders designed for use with bisecting technique will most likely have a short/long bite block | short |
| __________ is achieved by directing central ray of x-ray beam perpendicular to curvature of arch, through the contact points of these teeth | horizontal angulation |
| Curvature of the arch | mean tangent |
| When the vertical angulation is excessive | foreshortened image |
| When the vertical angulation in inadequate | elongated image |
| When utilizing bisecting technique, central ray of the x-ray beam is directed | perpendicular to the bisector |
| Which of these target-image receptor distances is recommended for use with bisecting technique | 8 in. |
| When utilizing bisecting technique, image receptor is placed | as close as possible to the tooth |
| What term describes imaginary line between long axis of tooth and plane of image receptor | bisector |
| Image receptor holders designed for use with bisecting technique should have a | short biteblock and 105degree backing |
| What is suggested point of entry for directing central ray of x-ray beam when exposing maxillary incisors radiograph using bisecting technique | tip of the nose |
| Radiation that may travel in direction opposite that of original x-ray. New x-ray may undergo another Compton scattering or it may be absorbed by photoelectric effect interaction | secondary radiation |
| The sum of inherent and added filtration a) added filtrationt b) inherent filtration c) total filtration | c) total filtration |
| Filtration built into machine by the manufacturer a) half value b) finished filtration c) secondary filtration d) inherent filtration | d) inherent filtration |
| Placement of aluminum discs in path of x-ray beam between port seal of tube head and PID a) added filtration b) secondary filtration c) simple filtration | a) added filtration |
| Beam filtration must comply with state and federal laws, safety requires an equivalent of _________ for x-ray machines operating in ranges below 70 kVp a) 2.5mm of aluminum b) .5mm of tin c) 1.5mm of aluminum d) 3.5mm of aluminum | c) 1.5mm |
| X-ray machines operating over 70kVp require minimum of _________ of beam filtration to comply with state and federal laws a) 2.0mm aluminum b) 2.5mm aluminum c) 3.0 mm aluminum | b) 2.5 aluminum |
| The ___________ of an x-ray beam is thickness (measured in mm) of aluminum that will reduce intensity of beam by one-half a) face value layer b) half-value layer c) the value of the layer | b) half-valued layer |
| _________ controls size and shape of useful beam a) collimation b) collimator c) filtration | a) collimation |
| ________ is absorption of long wavelength, less penetrating, x-rays of polychromatic x-ray beam by passage of beam through sheet of material a) fusion b) filtration c) elimination | b) filtration |
| Collimation reduces _______ a) exposure b) density c) beam strength d) scatter radiation | d) scatter radiation |
| ________ shape of collimator reduces size of x-ray beam and amount of scatter radiation (best to use) a) circular b) square c) rectangular | c) rectangular |
Created by:
welchang
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