1. Historical Development
CT scanners are categorized into several generations depending on the type of detectors, scanning method etc

2. First Generation Scanners
Single detector, single x-ray tube, rotate/translate pencil beam system, rotation angle/step 1°
Long scan time
Poor spatial resolution
Best scatter rejection

4. First generation model of a CT head scanner

7. Second Generation Scanners
Linear array of about 30 detectors, single x-ray tube, rotate/translate motion, narrow angle (10 ° ) fan beam
rotation angle/step 10°
Shortest scan time was about 18 s per slice

8. Third Generation Scanners
Linear array of about 800 detectors, single x-ray tube, rotate/rotate motion only, wide fan beam to cover the entire patient
Scan time of newer scanners is about ½ s per slice
Can produce ring artifacts

9. Fourth Generation Scanners
Complete circular array of about 4800 stationary detectors
Single x-ray tube rotates with in the circular array of detectors
Wide fan beam to cover the entire patient
Scan time of newer scanners is about ½ s per slice
Designed to address ring artifacts

10. Fifth Generation Scanners
210° arc array of stationary detectors
x-rays are produced from the focal track as high energy electron beam strikes the tungsten target
Scan time is about 50 ms per slice
Developed for cardiac tomographic imaging

13. Three major components of EBCT scanner:
A – Electron gun
B- Tungsten targets
C - Detectors