Help
Options
Question
mAs literally determins what
click to flip
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't know
Question
what imaging system has a linear exposure relationship?
Remaining cards (87)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Stack #735079
| Question | Answer |
|---|---|
| mAs literally determins what | the number of electrons boiled off of the filament |
| what imaging system has a linear exposure relationship? | digital |
| over exposed or underexposed between the two which one would be least likely to be repeated? | overexposed |
| ___ represents the different absorbtion characteristics of the body | density |
| with film/screen systems image density is represented by twhat? | Black metallic silver deposit patterns |
| What happens to density as processing developer temp. increases? | it increases |
| what happens to density if collimation is increased? (field size is made smaller?) | it decreases |
| the intensity of a beam is less on which end of the tube? | Anode |
| all other factors remaining constant, if the intinsifying screen is switched to a faster one, what effect will it have on density? | it increases |
| As kVp increases and everything else remains constant what happens to density | it increases |
| what is the absorbing material in a grid? | lead |
| according to the inverse square law if the sistance is reduced to 1/2 the intensity will? | increase by a factor of 4 |
| total filtration in the x-ray tube head assembly affects density by___ | removing low energy photons |
| what happens to density with increase in tissue thickness? | it will decrease |
| which set will produce the highest contrast? 50@20, 58@10, 67@5, 77@2.5 | 50@20 |
| the lower the kVp the _____ resultant of contrast | higher |
| what tissue group will likely have the greatest xray absorption? | bone |
| which difference in densities will have the lowest contrast? 1.8, 1.5, 1.0, 0.5 | 0.5 because the lowest difference between densities will present low contrast |
| where does black metallic silver formation begin? | sensitivity speck |
| what layer in general film is not duplicated? | the base |
| which layer is manufactures to reduce eye strain? | the base |
| a grid will _____ scatter production... how/why? | decrease, it only reduces the amount of scatter that reaches the receptor... |
| an increase in developer time will ____ contrast | decrease |
| a compensating filter will ________ contrast | decrease |
| scatter _____ contrast | decreases |
| collimation ____ contrast | increases |
| the level or degree of penetration of the xray beam is a primary factor in determining _______ | the scale of contrast |
| the higher the kvp and mAs the ________ density | greater the |
| the lower the kVp the ____ the contrast | higher |
| scatter, patient dose, density... which one does kVp affect? | all of them |
| primary controller of density | mAs |
| ___ literally controls the current through the xray tube | mAs |
| what determins the energy of the x-ray beam? | kVp |
| 20 mAs is used at 40'' SID what will the mAs be at 72 '' SID | 65 mAs |
| 24 mAs is used for a slow speed screen... what would the mAs be for a fast moving screen? | 6 new mAs=24*(1/4) |
| if the collimation field is made smaller what will happen to the density if the mAs is not adjusted? | it will decrease |
| purpose of a grid? | absorb scatter |
| 20 mAs is used for a non grid tech. what mAs should be used for an 8:1 grid? | 80 |
| increasing the screen speed allows for a reduction in ____ needed | mAs |
| if changed from a 11x14 cassette to a 10x12 cassette what adjustment needs to be made and why? | increase mAs because the photons that would have exposed the patient or the image receptor are removed. |
| to obtain a higher scale of contrast you must _____ kVp and ____mAs | decrease;increase |
| for every 4-cm change in tissue thickness mAs must be changed by ____ | a factor of 2 |
| ____ controls the overall blackness of a radiograph? | mAs |
| the ____ the SID and the ____ the OID the sharper the image | longer;shorter |
| films with thicker emulsions or larger silver halide crystals will have ______ sharpness | less |
| in digital, changing a negative image to a positive image is called what? | image inversion |
| adjusting the brightness and contrast is called what? | window and leveling |
| in a psp plate the trapping of electrons in the conduction band creates what? | latent image |
| which kVp is capeable of producing the lowest contrast? 50,60,70,80 | 80, the higher th kVp the more penetration resulting in a low contrast image |
| which kVp setting will provide the most kenetic energy to filament electrons? | 100 the higher the kVp the more energy |
| which xray energy would have the lightest shades ? 20 50 80 or 100 | 20 less energy more chance of the photons being absorbed in the body less hitting the IR |
| which tissue group has the lowest water content? | fat |
| which tissue group has the highest water content? | muscle |
| what is the primary absorber of xrays in bone? | calcium |
| in which layer of the intensifying screen is xray energy converted into light? | active layer |
| which layer of film contains halide crystals? | emu;sion |
| once the halide crystals are exposed the sensitivity speck will first aquire what charge? | negative |
| why is scatter exposure undesirable? | it decreases contrast |
| compensating filters in effect _____ tissue thickness and density | increase |
| which OID would result in the greatest increase in radiographic contrast? 1,4,6,12 | 12 |
| positive contrast media will ____ contrast | increase |
| what increases the voltage to kilovoltage in the xray circuit? | step up transformer |
| if the lead strips are 4.0 mm high and are separatedby an interspace of 025mm what is the grid ratio? | 4.0/.25 = 16:1 |
| if lead strips are 2.0mm high and are separated by an interspace of.25mm what is the grid ratio? | 2.0/.25=8:1 |
| s radiograph is produced using 85@8 without a grid. a second film is requested using an 8:1 grid with a conversion factor of 4 what mAs is needed? | 8 * 1/4 = 32/1 = 32 mAs (cross multiply |
| 1st radiograph is 85@10 without a grid what would be the mAs if using a 16:1 grid?(conversion factor of 6) | 10* 1/6 = 60/1 = 60 mAs |
| 1st image used 85@30 with a 12:1 grid 9conversion factor 5) 2nd film will be same tech. with a 16:1 grid (conversion of 6) what mAs is needed | 30* 5/6= 180/5 = 36 mAs |
| what are the grid-conversion factors for no grid, 5:1, 8:1, 12:1, and 16:1 grids? | 1,3,4,5,6 |
| when the patient thickness is more that 10cm the kVp should be | greater than 60 |
| transmission is responsible for what? | the dark areas on the image |
| absorption is responsible for | the light areas |
| the higher the frequency of a grid the ____ the interspace must be... & the ___the grid ratio | thinner;higher |
| contrast is _____ when a grid is used | doubled |
| what will go down, what must be increased, when a grid is placed in beam? | density will go down, exposure factors must be increased to compensate |
| parallel linear grid | all lead sstrips are parallel to eachother, they absorb a large amount of the primary beam resulting in some cut-off |
| with a decrease in SID grid cut-off will | increase |
| criss-cross ot cross hatched or cross grid | horizontal lead strips, vertical lead strips, primary beam must be centered perp. to grid, grid must remain flat |
| focused grid | fabricated so the strips are parallel to the primary xray path across the entire image receptor. minimizes grid cut-off |
| focused linear grids | lead strips are angled to match divergence of beam, primary beam will align with interspace material, scatter absorbed by lead strips |
| focused linear grids | convergence line, narrow positioning latitude, improper centering results in periphereal cut-off, only useful at present SID distance |
| which grids require careful alignment with tube? | higher frequency grids |
| what are the four main grid errors? | off-level, off-center, off focus, upside down |
| the central axis is not perpendicular to the grid, and if partial cut off occurs over the entire image receptor and comes out underexposed what type of error is this? | off level |
| when a focused grid has partial grid cut-off over t he entire image nad it looks underexposed what type of error is it? | off center |
| if a grid is not positioned at the specified focal distance, grid cut-off occurs and the optimal density decreases with distance from the central ray... cut off is toward the edge of image... what error? | off focus |
| if complete grid cutoff occurs except in the central region of the central ray what error is it? | upside down grid |
| which grid is better, focused or parallel? | focused |
| what are the three factors to consider with grid selection? | kVp, degree of clean-up, patient dose |
Created by:
b.xray