Generations of CT Scanners

Scanner CT (évolution) de générations de scanners CT - Apprentissage par tomodensitométrie

generations of ct scanners - computed tomography learning

CT scanners were first introduced in 1971 with a single detector for brain study under the leadership of Godfrey Hounsfield, an electrical engineer at EMI (Electric and Musical Industries Ltd). Thereafter, it has undergone several changes 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

GENERATIONS OF CT SCANNERS

The different generations of CT scanner was developed over the years to increase scan time and efficiency of scanning. The changes were majorly on the X-ray tube and detector arrangements.

Major adjustment in the technology of CT scanners were manifested in

Tube orientation and shape of beam (from pencil beam through narrow beam to fan beam)

Number of detectors (from single detectors to multiple detectors).

Detector arrangement.

Slip ring technology.

This primarily led to decrease in scan time and increase in efficiency of the scanners.