CT scanner (evolution)
Last revised by Dr Bálint Botz ◉ on 15 Dec 2020
Citation, DOI & article data
Citation:
Shetty, A., Botz, B. CT scanner (evolution). Reference article, Radiopaedia.org. (accessed on 06 Jul 2022) https://doi.org/10.53347/rID-29733
Permalink:
rID:
29733
Article created:
18 Jun 2014 by Dr Aditya Shetty
Revisions:
22 times by 9 users - see full revision history
Systems:
-
Section:
Synonyms:
- Generations of CT scanners
- Evolution of CT scanners
CT scanners were first introduced in 1971 with a single detector for brain study under the leadership of Sir Godfrey Hounsfield, an electrical engineer at EMI (Electric and Musical Industries Ltd). Thereafter, it has undergone multiple improvements with an increase in the number of detectors and decrease in the scan time.
First generation
- detectors: one
- type of beam: pencil-like x-ray beam
- tube-detector movements: translate-rotate
- duration of scan (average): 25-30 mins
Second generation
- detectors: multiple (up to 30)
- type of beam: fan-shaped x-ray beam
- tube-detector movements: translate-rotate
- duration of scan (average): less than 90 sec
Third generation
- detectors: multiple, originally 288; newer ones use over 700 arranged in an arc
- type of beam: fan-shaped x-ray beam
- tube-detector movements: rotate-rotate
- duration of scan (average): approximately 5 sec
Fourth generation
- detectors: multiple (more than 2000) arranged in an outer ring which is fixed
- type of beam: fan-shaped x-ray beam
- tube-detector movements: rotate-fixed
- duration of scan (average): few seconds
Other technologies
Other CT technologies have been adapted to third and fourth generation scanners, including:
-
helical ("spiral") image acquisition
- used in all modern CT machines
- slip-ring technology made helical acquisition possible
- dual energy CT scanning
Practical points
- third and fourth generation scanner technologies are both used in many health care settings
- the fourth generation is a fundamentally different acquisition method, but the resulting image quality is similar to the third generation for most applications
See also
References
- 1. Curry TS, Dowdey JE, Murry RE. Christensen ́s physics of diagnostic radiology 4 Ed. Lippincott Williams & Wilkins. (1990) ISBN:0812113101. Read it at Google Books - Find it at Amazon
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