| Question |
 |
|
| Answer |
|
|
| what is a intensifying screen used for |
used for lowers the patients dose |
| what is a intensifying screen |
a device that converts the energy of the x-ray beam into visible light |
| what is psp |
Digital IR:photostimulable phosphor plate |
| what is psp used for |
used in CR is barium flourochalide bromides with europium activitors |
| what is DR radiation detectors made of |
amorphous selenium |
| what are the layers of the intensifying screens |
base,reflective layer,phosphor layer,propective coating |
| what does the protective coating do |
closest to the film,protects screen from damage,help eliminate static electricity |
| what does the phosphor layer do |
active layer of screen |
| what are our screens made out of |
lanthanum and yttranium |
| what converts the x-ray beam into light |
the phosphor |
| what does the reflective layer do |
increases the efficiency of the beam |
| what is isotopic emission |
radiation with equal intensities in all directions. |
| what does the base do |
mechanical support for phosphor layer |
| what is the base made out of |
polyester |
| what is luminescence |
the light emitted from the screen |
| what does luminescence do |
excite the outer electrons and forms light as they fall back into place |
| what are the 2 types of luminescence |
flouorescence and phosphorescence |
| what is flouorescence |
if visible light is emitted,only when the phosphor is stimulated |
| what is phosphorescence |
if the phosphor continues to emit light after stimulation(screen lag/afterglow) |
| what does the screen speed tell us |
describes how efficiency x-rays are converted into light |
| what is the intensification factor |
the ratio of the exposure require to produce the same optical density with a screen to the exposure required to produce a optical density without a screen |
| what is the intensification factor |
IF=exposure required without screen------------------------------------ exposure required with screen |
| what is the cassette made of |
plastic-low atomic# for minimal attenuation of the beam |
| why is metal used as a back cover |
to reduce backscatter |
| what do you get if you used faster speed |
low contrast,wider latitude,less detail,increase density,less dose. |
| what do you get if you used slower speed |
high contrast,narrow latitude,greater detail,decrease density,increase dose |
| why do we do a wire mesh test |
checks for good screen-film contact |
| what is film sensitometry |
measurement of the response of film to exposures & processing & then measuring & evaluating the densities |
| most screens must be cleaned |
every 2 to 3 months,in busy center cleaning every month |
| what are artifacts on the radiograph |
undesirable optical densities or blemishes on a radiograph |
| what color is the artifacts after exposure |
artifacts appear black |
| what color is the artifact before exposure |
artifact appear white |
| radiation fog & safelight fog will do what do density |
both will show increased density |
| kink marks(cresent) fingernail or bending will show what density |
increased density |
| what is a penetrometer |
(step wedge) aluminum steps used to monitor x-ray equipment |
| what is a sensitrometer |
used for processor quality control |
| what is a densitometer |
instrument that provides a readout of the amount of density on a film |
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