CT Flashcards
Which generation scanner leaves a ring artifact?
3rd
Which generation scanner has the highest patient dose?
4th
Which generation scanner takes the longest to scan?
1st (5min)
Which generation scanner first developed a fan-shaped beam?
2nd
Which generation scanner has a translate-rotate configuration?
1st & 2nd
Which generation scanner first started a multidetector array?
2nd
Which generation scanner has a rotating x-ray source and a stationary detector?
4th
What is the scan time for 4th generation scanners?
1 sec
Which generation scanner does not result in a constant beam path from the source to all detectors?
4th
What types of collimators exist for CT?
a) prepatient coliimator
- - mounted on the x-ray tube
- - decreases patient dose
- - determines the slice thickness
b) predetector collimator – reduces scatter radiation to the detector array
- - improves image contrast
- - does not affect patient dose
What is the purpose of the bow-tie filter in the 2nd generation scanner?
Given the shape of the patient and the fan shaped beam, there is increased intensity towards the edges of the beam. The bow-tie filter helps solve this.
What is the difference btwn the 1st generation and 2nd generation scanners?
1st – pencil beam; one detector; 5min scan; 180 translations
2nd – fan-shaped; detector array; increased intensity at edge of beam; 30sec scan
What measures at 0 HU?
Water
What measures at +1000 HU?
Compact bone
What measures at -1000 HU?
Air
