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image acqusition and
| Question | Answer |
|---|---|
| Gemoetric blue can be evaluated using what three | star pattern, slit camera and pinhole camers |
| what pixel sice has a 512 X 512 matris witha 20-cm FOV? | FOV/MATRIX=pixel size....20cm=200mm 200/512=0.39 mm/pixel |
| in electronic imaging, as digital imaging matrix size increases, pixel (increases or decreases) | decreases |
| most laser film must be handled in | total darkness |
| name two effects tht an in crease in kilovoltage will have | more scatter radiation will be produced, and the eepsoure rate witll increase |
| decreasing field size from 14x17 in to 8x10 in, with no other changes will (increase or decrease) radiographic densith and (increase or decrease) the amount of scattered radiationa enerated within the part | decrease and decreaase |
| the componnet of a CR imaging plate that records the radiologic image is the | PSP |
| a lateral radioggraph of the c spine was made at 40 in using 300 man and 0.03 second exposure. If it is desired to increase the distance to 72 in, what should be the new mA setting, all other factors remaining constant | old mAs/new mAs=old D^2/new D^2 9/x=1600/5187 9/x=1,600/5,184 x=291.6 |
| regarding x-ray absorptiometry, is radiation dose low? | yes |
| regarding x-ray absorptiometry, do only low energy photons get used | no |
| regarding x-ray absorptiometry, photon attenuaiton by bone is calcualted (T/F) | T |
| the luminescent light emitted by the PSP is transformed into the limage seen on the CRT by the | ADC |
| IF THE QUANTITY OF BLACK METALLIC SILVER ON A PARTICULAR X-RAY FILM IS SUCH THAT IT ALLOWS 1% OF THE ILLIMINATOR LIGHT TO PASS THROUGH THE FILM, THAT FILM HAS A DENSITY OF | 2.0 |
| using a fixed millampere-seconds and variable kilovoltaghe factors, each centeimeter increase in patient thinkenss requires what adjustment in kv? | decrease of 2 |
| ifa duration of 0.05 second was selected for a particualr exposure, what mA would be necessardy to produce 30mas | mA x s= mAs 0.05x=30 x=600mA |
| x-ray photon energy is (directly or inversly) related to photon wavelwngth | inversly |
| using an AEC system, how will the mAs be adjusted as the film-screen speed combination is decreased? | it will remain the same |
| resolution in CR increases as laser beam size (inrcreases/decreases) and PSP crystal (increases/decreases) | decreases/decreases |
| In radiography of a large abdome, name one way to minimize the amount of scattered radiation reching the IR | collimation |
| does the feild size affect the exposure rate of the promary beam | no |
| in general, as the intensification factro increases, radiographic density (increases/decreases) | increases |
| radiographic contrase is a result of d__ t__ a__ & e__ c__ | differential tissue absorption & emulsion characteristics |
| grid ratio = ____/___ | height of lead strips/width of interspace material |
| a 5 in object to be radiographed at a 44 in SID lies 6 in from the IR. WHat will be the image width | Image size/object size=sid/sod x/5in=44in/38in x=5.78 image width |
| in comparison with 60 kv, 28 will permit (lesser/greater) exposure lattitued, and produce (more/less) scattered radiation | greater/more |
| mislaignment of the tube-part relationship results in ___distrotion | shape |
| causes of grid cut off, when using focused reciprocating grids, include (1) | inadewuate SID |
| using a short (25-30 in) SID with a large (14 X 17 in ) IR is likely to (increases/decreases)the anode heel effect | increase |
| chemical fog may be attributed to --- developer temp, ___developer, and ___replenihsment | excessive developer temp, oxidized developer and excessive replenishment |
| with a given exposure, as intensifying screed speed increases, how is radiographic density affected? | increases |
| using a 48 in SID, hom much OID ;must be introduced to mag a object 2 times? | 24 in OID |
| a particualr radiograph was produced using 12 mAs and 85 kV with a 16:1 ratio grid. THe radiograph is to be repeated using an 8:1 ration grid. What should be the new millampere seconds value | old mas/new mas=old grid factor/new grid factor 12/x=6/4 8 |
| name three phosphor variables that determines the quantity of fluprescent light emitted from a fluoresctent screen, | thinkness, type and size of the phosphor |
| use of (high/low) kv exposure factors would remedy the effect of very dissmilar tissue densities | high |
| name two methods of loimiting the production of scattered radiation | prone position for abd pics, collimation to the smallest area possible |
| name two types of shape distortion | elongation and foreshortening |
| during CR imaging, the latent image present on the PSP is changed to a computerized image by the | ADC |
| is mA related to recorded detail | no |
| is focal spot size related to recorded detail | yes |
| is screen speed related to recorded detail | yes |
| is OID related to recorded detail | yes |
| a satisfactory pic was taken made using a 36-in SID, 12 mAs and 12:1 grid. If the exam will be repeated at a distance of 42 in and isong a 5:12 grid what should be the new mAs value to maintain the original density? | old mas/new mas=old D^2/new D^2 12/x=36^2/42^2 thus x=16.33@42 then old mAs/newmAs=old grid factor/new grid factor 16.33/x=5/2 6.53 |
| the greatest radiographic density will be produced by the combination of the (highest/lowest) mAs and the (shortest/longest) SID | highest and shortest |
| does the mA have an effect on radtiographic contrast? | no |
| name two factors that have a dignificant effect on radiographic contrast | kV and grid ratio |
| what is likely to reslut form using single emulstion fril in an IR that has a two intensifying screens? | descease density |
| a 15% decrease in kV accompined by a 50% increase in mAs will result in a (longer/shorter) scale of contrase | shorter |
| does focal spot size impact recorded detail? | yes |
| does subject motion impact recorded detail? | yes |
| does SOD impact recorded detail? | yes |
| how are mas and radiographic densith related in the process of image formation | directly proportional |
| cassett front material can be made of what two materials | carbon fiber and magnesium |
| if a radiograph exposed using a 12:1 grid ration exhibits a loss of density at itd lateral edges, it is probably becuse the SID was too (great/short) | great |
| practices that enable a radiographer to reproduce the exposure time required for a particualt image include use of a (higher/lower) mAs, use of a (higher/lower) kV, use of (slower/faster) film-screen combination | higher, higher, faster |
| if 400 mA, 10ms, and 90 kV were usd for a particualr exposure using three-phase, 12 pulse equipment, use of what time (in seconds) woudl be apporporiate for use on single-phase equipment to produce a similar change | 0.02 seconds |
| name two materials that may be used as grid interspace materials | plastic and aluminium |
| name two factors that can impact the visibility of the anode heel effect | SID and IR size |
| an increse in the Kv is applied to the x-ray tube increases the | exposure rate |
| exposure rate will decrese with an increase in | SID |
| name the pathologic condition that will require a decrease in exposure factors | osteoporosis |
| if a radiograph exhibits insufficient density, this might be attributed to inadequate __, and __ __ | inadequate kv and grid cut off |
| name two methods that help reduce the procudtion of scattered radiation | compression and beam restriction |
| will the use of a grid help reduce scattered radaition | no |
| name two factors that accest botht the quanitiy and quality of the primary beam | HVL and kV |
| the squeege assembly in an automatic processor functions to remove ___ __ from the films and is located near the ___ ___ | escvess solution and located noear the crossover rollers |
| an AP pic of the femur ws made using 300mA, 0.03 second, 76 kV, 40 in SID, 1.2 mm focal spor and 400 speed film screen system. WIth all other factors remianing constant, what time would be needed to maintain desity at 44 SID using 500 mA? | old mas/new mas=old d^2/ new d ^2 9/x=40^2/44^2 x=10.98 then we want 500 mA 500x=11 x=0.022 |
| the sensitometric curve may be sued to identify ___ ___ porblems, and determine film ___ | automatic processing problems and determine film sensitivity |
| in a PA chest beign sued for cardiac evaluationl the heart mesures 14.7 cm between its widest points. If the mag factor os lmpwm tp be 1.2, what is the actual diameter of the heart | 12.25 cm |
| the microswitch for controlling the smnt of repnishemtn used in an automatic processor is located at the _____ ____ | entrance roller |
| what is the propose of the thin layer of lead that is oftgen located behind the reat intensifying screen in an IR | to prevent scattered radiation fog |
| (decreased/increased) mAs, (decreased/increased)kV, and (fast/slow) film screen speed is most likely to be associated with quantnum mottle | decreased mAs, increased kV and fast screen film speed |
| what pixel sixe has a 2,048 x 2,48 matrix qith a 60-cm FOV? | FOV/martix=pixel size so 60cm=600mm 600/2,084=0.35 mm |
| which of the following possess the widest dynamic range?: high speed screens, slow speed screens, AEC, CR | CR |
| the exposure facrors of 400mA, 17 ms, and 82 kV produce a mAs value of | mA x seconds 400 x .017=6.8 |
| a change from 400 speed 200 speed would require what change in mAs | it sould be doubled |
| a focal spot size of 0.3 mm of smaller is essential for | mag radiography |
| what focal spot size is necessary for mag radiography | 0.3 mm or smaller |
| name two exams that the anode heel effect can be important consideraterio | lateral t spine and AP femur |
| a pic made with a parallel grid demonstrates decreased density on its lateral edges. This is most likely due to (decreased/increased)SID | decreased |
| if 300 mA has been selected for a particualr exposure, what exposure time woudl be required to produce 6 mAs | 300x=6 x=20 |
| an increase in kV will serce to procude a longer/shorter scale of contrast | longer |
| the functions of aoutomatic beam limiter decised inscluse reducing the | production of scattered radiation |
| radiographic recorded detial is inversli related to what two things | OID and imaging system speed |
| the single most impotant factor regualting radiographic contrast is | kV |
| the lower the Kv the (shorter/longer) is the scale of contrast | shorter |
| the device used to give film emilsion a predetermined exposure in order to test its response to processing is called the | sensormiter |
| what device requires two exposures to evaluate focal spot accuracy? | slit camera |
| becuase of the anode heel effect, the intenisty of the x ray beam is greatest along the (anode/cathode) end of the beam | cathode |
| a film emulsion having a wide lattitude is likely to exhibit (low/high) contrast | low |
| can changes in mAs affect recorded detali | no |
| can changes in mAs affect optical density | yes |
| can changes in mAs affect exposure rate | yes |
| can changes in mAs affect quantity of x ray photons produced | yes |
| low kV exposure factors ususally are indicated for radiographic exams using ___-___, ____media and (positive/negative) contrast agent | water-soluble, iodinated media, negative |
| base plus fog is a result of __-tinted film base, ___ ____, and the ____ ____ | blue, chemical developemnt, and the manufacuteinf process |
| a decrease in kV will result in a (increase/decrease)in optical density | decrease |
| the cause of films coming from the automatic processor still wet can be | insufficiten hardening action |
| the term ___ describes an emilsion's ability to recoed a range of densities and the degree of error tolerated with given exposure factors | lattitude |
| a decrease from 200 to 100 mA will result in a decrease in what two factors | exposure rate and beam intensity |
| what two apparatuses are needed for the costnructiopn of a sonsometric curve? | penetrometer and densitometer |
| the quality of scattered radiation reaching the IR can be reduced throufh the use of what two things? | air gap technique and a stationary grid |
| name three conditions that contribute to poor radiographic film archival quialty | fixer retention, insufficient developer repelnishment, and poor storage conditions |
| what does a 5:1 grid allow for | positoning lattitude |
| an x ray exposure of a particualr part is made and restricted to a 14 x 17 in feild size. the same exposure is repeated but the beam is restricted to a 4 x 4. COmpared, the seond image will have (more/less) density and (more/less) contrast | less density and more contrast |
| when a slow screen film system is used with a fast screen film AEC system, the resulting images | are too light |
| any images obtained using dual x ray absorptionetry (DXA) bone densitometry are used to evaluate accuracy of the | region of interest |
| a pic made using 300 mAm 0.1 second and 75 kV shows motion unshapness but otherwise ok, The pic will be repeated using a shorter tiem. Using 86 kV and 400 mA, what shoudl be the new tiem? | mA x time=mAs 300 x .1=30 then kV was increased by 15% same as dbl mAs now only 15 mAs is required so 400x=15 x=.0375 s x=37.5 ms |
| name two exposure type artifacts | poor screen film contact, and motion |
| is chemical fog a exposure type articact | no |
| when blue emitting rare earth screens are matched properly with the correct fils emulsion, what type of safelights should ce sued in the dark room (2) | red and GBX-2 |
| what effect will a stained intenisfyign screen have on the finished radiograph | decreased densty |
| a compensating filter is used to | even out widely differing tissue desnsities |
| boxes of film stored in too watm an area may be subject to | film fog |
| what term is used to describe unsharp edges of time radiographic details | blur |
| is lanthanum oxide a rare earth phosphor | yes |
| is gadolinium oxysulfide a rare earth phosphor | yes |
| is cesium iodide a rare earth phosphor | no |
| as grid ratio is decreased, the scale of contrast becomes (longer/shorter) | longer |
| x ray film emulsion is most sensitive to safe light for at what time | after exposure |
| which focal spot size can be used for mag radiography; .2 mm .6 mm 1.2 mm or 2.0 mm | .2 mm |
| if a 6 in OID is intrduced in a particualr exam, what cnahge in SID will be necessary to overcome magnification | to compensate for every 1 in of OID, an increase of 7 in of SID is required. Therefore 6 needs 42 in |
| if a grid has lead strips 0.4 mm thick, 4.0 mm high and 0.25 mm apart, what is its grid ratio | 4.0/0.25=16:1 |
| what factor has the greatest effect on radiographic density | SID |
| the continued emission of light by a phosphor after the activating source has ceased is termed | phosphorescence |
| indigital imagein, as the size of the image matris increases the pixel size (increases/decreases) and spatial resoltion (increases/decreases) | pixel decreases and resoution increases |
| exposed silver halide crystals are changed ito black metallic cilver by the | reducers |
| gemoetric unsharpness is directly influenced by what factor | OID |
| what factro can affect the amount of developer replenisher delivered per film in an automatic processor | film size |
| what factor is directly related to photon energy | kV |
Created by:
amanda.clark