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fluoro
| Question | Answer |
|---|---|
| CCD | charged coupling device |
| the intensifier was introduced in the | 1950s |
| converts incoming photons to light | input phosphor |
| photocathode | converts light to electrons |
| shape and directs electron stream to preserve image detail | focusing lenses |
| role of the anode in the intensifier | accelerates the electrons |
| output phosphor | converts the accelerated electrons into a brighter light |
| cesium iodide makes up the | input phosphor |
| photoemission is performed by the | photocathode- converts light to electrons |
| the input phosphor absorbs ____% of xrays | 60 |
| the photocathode is made of | cesium and antimony |
| the output phosphor is composed of | Zinc Cadmium Sulfide |
| the image created by the intensifier is ____ times brighter than the original image | 5000-10,000 x |
| brightness gain = | minification gain x flux gain |
| minification gain = | (diameter of the input phosphor / diameter of the output phosphor)^2 (Di/Do)^2 |
| Flux gain = | # of output light photons / X of input Xray photons |
| transfers the visible light emitted from the intensifier to the digital monitor | charged coupling device |
| two types of monitors | liquid crystal display monitors and plasma monitors |
| plasma monitors are used | in IR, more expensive. the clearest picture |
| conversion factor is another way to describe | brightness gain |
| the antiquated CCD | camera tube |
| mag mode works by | decreasing the fov on the input phosphor. similar to collimation. image appears brighter and clearer. |
| which monitor type is common practice | liquid crystal display monitors |
| the issue with plasma monitors is that they can create | internal artifact |
| modern C-arms replace the intensifier with | flat panel detectors |
| FPDs advantages over intensifier | intensifiers need an ADC. FPDs produce a direct digital signal. FPDs reduce dose, no light loss to conversion, higher detector quality efficiency. they're also lighter |
| DQE | detector quantum efficiency. how good the IR is at picking up radiation |
| dose monitoring units | air kerma (kinetic energy released in matter) in grays |
| DAP contributes | air kerma |
| meter that monitors dose | DAP/KAP |
| indicator of pt skin dose | air kerma |
| indicator of overall pt radiation risk | DAP |
| pixel binning | combining adjacent pixel data to form larger pixel bunches. a way of making the image if there is not enough signal. decreases spatial resolution. better SNR, less quantum mottle. |
| HVL for filtration | how much Al or lead it takes to drop the exposure to half |
| added plus inherent filtration | 2.5mm Al |
| kVp accuracy was previously measured with a | Wisconsin test cassette |
| The measured kVp and the control panel kVp should be within ____ of each other | +/- 5% |
| Linearity variance of mA values should be within | 10% |
| With binning you can use less dose, but ___ decreases and ____ increases. | spatial resolution decreases, SNR increases(improves) |
| when using a smaller "field of view", binning causes | better spatial resolution |
| the essential reason for binning is to | lower pt dose |
| Automatic Brightness Stabilization System (ABS) aka | adjusts radiation output for changes in part thickness. aka AERC- automatic exposure rate control. |
| difference btwn ABS and Automatic gain control | AGC changes signal gain while automatic brightness stabilization changes radiation output. Both maintain brightness. |
| What is the maximum entrance exposure rate /min for units with ABS | 10 R/min (2.6 mCkg-min) for units with ABS. The max intensity that can enter the pt |
| What is the maximum entrance exposure rate /min for units withOUT ABS | 5 R/min |
| Minimum SID for fluoro units(stationary) | 15 in/ 38cm |
| minimum SID for Mobile units | 12 in |
| minimum SID for specialized units | 8 in or 20cm |
| Difference between quantum mottle and electronic noise | quantum mottle is dose dependent. Electronic noise is dose independent. both look the same |
| how much lag is allowed for cardiac, vascular and interventional studies? | 10% |
| how much lag is allowed for GI studies? | 20% |
| decreased temporal resolution is the same as | motion blur |
| what test is used to evaluate lag? | spinning wheel with numbers |
| relative conversion factor measures | the efficiency of the machine from Xray to light conversion. |
| Would a decrease of 60% in relative exposure factor be acceptable | no. anything more than 50% fails |
| The spinning top test evaluates the | timer accuracy. uses pulses |
| DICOM | Digitial Imaging and Communications in Medicine. How gray levels should map to luminance |
| AAPM | American assoc of Physicists in Medicine. the actual test patterns to check compliance |
| SMPTE | |
| What tests new monitor installation | SMPTE |
| GSDF | gray scale display function |
| what determines that all rad monitors have the same gray scale | GSDF- the recipe. the look up table is the chef |
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