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By: Masood Ahmed (Radiographer)Aga Khan University Hospital Karachi.

Second Generation

Third Generation

Fourth Generation

Electron Beam CT

First Generation

Generation

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The term generation has been applied because of the order in which the CT scanner designs have been introduced, and each has a number associated with it. Progress was rapid so the fourth-generating CT imagers appeared in 1978, just 6 year after the first ct imager.Unlike Hounsfield's early experiments, the patient does not move during CT, except for spiral CT rather , the x-ray source and the image receptor move.

Generations

Last Updated: April 8, 2023

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By: Masood Ahmed (Radiographer)Aga Khan University Hospital Karachi.

Second Generation

Third Generation

Fourth Generation

Electron Beam CT

First Generation

Generation

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Finely collimated x-ray beam (pencil beam) was used in first-generation CT images.Single radiation detector.Translate-rotate motion.180 translations with 1degree rotation between translates.Single image projection per translation.Five minute image time.Head imager only, not capable of body imaging.

First Generation.

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By: Masood Ahmed (Radiographer)Aga Khan University Hospital Karachi.

Second Generation

Third Generation

Fourth Generation

Electron Beam CT

First Generation

Generation

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Fan –shaped x-ray beam.

Multiple radiation detectors . A detector array.

Translate-rotate motion.

Usually 180 translations with 10 degree rotations between translations.

Multiple image projections per translations.

Approximately, 30 s imaging time.

Head and body imager.

Second Generation

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By: Masood Ahmed (Radiographer)Aga Khan University Hospital Karachi.

Second Generation

Third Generation

Fourth Generation

Electron Beam CT

First Generation

Generation

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A fan beam X-ray source is usedseveral hundred radiation detector The curvilinear detector array provides constant distance between source and each detector resulting in good image reconstruction.360 degree rotate-rotate mention. Hundreds of image projections are acquired during each rotation, Imaging time is reduced to 1 s or less.Ring artifacts are characteristic of third generation imagers.

Third Generation

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By: Masood Ahmed (Radiographer)Aga Khan University Hospital Karachi.

Second Generation

Third Generation

Fourth Generation

Electron Beam CT

First Generation

Generation

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Fourth generation was developed principally to suppress ring artifacts.Several thousand individual detectors.The mechanical motion is rotation of the x-ray source around a fixed detector array (rotate stationary).As the fan beam passes across each detector, and image projection is acquired.Imaging time is 1 s or less.

Fourth Generation

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By: Masood Ahmed (Radiographer)Aga Khan University Hospital Karachi.

Second Generation

Third Generation

Fourth Generation

Electron Beam CT

First Generation

Generation

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Fast imaging.Time less than 100ms, The x-ray source is not an x-ray tube but rather a focused, steered , and microwave-accelerated electron beam incident on a tungsten target.The target covers one-half of the imaging circle; the detector array covers the other half.The electron beam is steered along the curved tungsten target creating moving source.EBCT is principally applied to cardiac imaging .Heat dissipation no problem in EBCT.EBCT scan time as short as 50ms.

Electron Beam CT (EBCT)

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By: Masood Ahmed (Radiographer)Aga Khan University Hospital Karachi.

Second Generation

Third Generation

Fourth Generation

Electron Beam CT

First Generation

Generation

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