| Question |
Answer |
| Narrow window width produces what? |
short scale |
| Wide window width produces what? |
long scale |
| Window allows the viewer to alter what? |
contrast |
| Window level controls what? |
density |
| Window width controls what? |
contrast |
| BUN number range for contrast: |
7-18 |
| Creatnine number range for contrast: |
.6-1.5 |
| A “viscous” material is: |
thick |
| CTDI |
dose to pt within the primary beam |
| MSAD |
average dose pt receives during an exam |
| Noise in CT is: |
the variation in CT numbers above and below 0 |
| Linearity: |
calibration of CT scanner so that water = 0 |
| Most important component of the CT QC program is: |
spatial resolution test (bar or hole pattern) |
| Laser localizer for CT should be how accurate? |
to within +/- 1mm |
| How does pt dose change with slice thickness? |
thinner slices = more pt dose |
| Scintillation |
detector made of crystal with 50% detector efficiency. Most common. |
| Pre-patient collimation controls: |
pt dose |
| Postpatient (pre-detector) collimation controls: |
slice thickness |
| How must the CT computer be stored? |
in a cool dry place, under 68 degrees and 30% relative humidity |
| Formula for pixel size |
FOV / matrix size |
| Formula for voxel |
pixel size X slice thickness |
| CT numbers +1000 represent : |
hard bone |
| CT numbers -1000 represent: |
air |
| Ct numbers 0 represent : |
water |
| CT number range for lung tissue: |
-250 to -850 |
| CT number range for blood fluid: |
+25 to +50 |
Spanish 3
