5.2 CT: image quality and artifacts Flashcards
how many generations of CT scanners are there?
4
(pencil beam 1790, partial fan beam 1972, fan beam 1976, fan beam 1978)
which generation of CT scanners started using multiple detectors instead of just one?
2nd generation
which generation of CT scanners did we observe a significant improvement in duration of scan?
2nd generation
what was the “number of detectors” for each generation of CT scanners?
1st: one
2nd: multiple, up to 30
3rd: multiple, 288-700
4th: multiple, more than 2000
what was the “type of beam” for each generation of CT scanners?
1st: pencil-like x-ray beam
2nd: fan-shaped x-ray beam
3rd: fan-shaped
4th: fan-shaped
what were the “tube-detector movements” for each generation of CT scanners?
1st: translate-rotate
2nd: translate-rotate
3rd: rotate-rotate
4th: rotate-fixed
what is the “average duration of scan” for each generation of CT scanners?
1st: 25-30 mins
2nd: less than 90 sec
3rd: 5 sec
4th: few secs
describe the difference of tube-detector movements between the 3rd and 4th generation of CT scanners
3rd gen: detectors rotate together with the x-ray tube
4th gen: fixed detectors, rotation of only the x-ray tube
does a higher generation of CT scanners mean it is more advanced?
no, the 3rd gen is still used to today in some cases rather than 4th gen
what is a characteristic of ALL CT systems when it comes to x-ray tubes and detectors
in all systems, there is only ONE x-ray tube, and many detectors
what are the 2 types of beam?
- multiple pencil beams
- small fan beams