Computed Tomography - CT or CAT Scan
Hounsfield and Cormack Invented Computer Axial Tomography in 1972
Aug 30, 2008
Invented by engineer Godfrey Hounsfield and physicist Allan Cormack, the "computed tomography" (CT) scan, also known as "computed axial tomography" (CAT) scan, allows doctors to see the soft tissues inside the body, unlike the conventional X-ray that only allows the outline of bones and organs to be seen.
The CT scan uses a computer to produce detailed cross-sectional images of the body. This way, doctors can examine the body one narrow "slice" at a time to pinpoint specific areas of concern.
Inventors: Hounsfield and Cormack
Independently of each other, CT scan was invented in 1972 by British engineer Godfrey Hounsfield of EMI laboratories in England, and by South African-born physicist Allan Cormack of Tufts University in the US.
Early CT Scan Machines
The first machines were installed between 1974 and 1976, originally designed to scan the head of the body only. The whole body systems with studies became available in 1976. Today, an entire chest scan can be taken in 5 to 10 seconds using the most advanced multi-slice system.
Many of the improvements have been made in patient comfort, more anatomy being scanned in less time, and an increase in image quality. Recent researches are focused to provide excellent image quality for diagnostic confidence and the lowest possible X-ray dosage and exposure.
CT is Based on X-Ray Principle
A CT scan is based on X-ray principle. How it works is that, as X-rays pass through the body, they are absorbed at different levels, creating a matrix or profile of X-ray beams of different strengths. As the X-ray profile is registered on film, it creates an image. For a CT image, the film is replaced by a banana-shaped detector that measures the X-ray profile.
CT Scan Physical Appearance
A CT scan looks like a large square. The opening where the patient enters is 24 to 28 inches in diameter. Inside it is a rotating frame with an X-ray tube attached on one side and the banana-shaped detector mounted on the opposite side. A fan beam of X-ray is created as the rotating frame spins the X-ray tube and detector around the patient.
With the full rotation of the detector and the X-ray tube, the detector takes many snapshots of the X-ray beam. In one full rotation, about a thousand profiles are sampled. Each profile is subdivided spatially by the detectors, fed into numerous individual channels, and reconstructed backward by a dedicated computer into a two-dimensional image of the slice that was scanned. Multiple computers are used to control the entire scan process with a "host" computer leading the entire system.
Importance of CT Scan
Thanks to great minds of inventors Godfrey Hounsfield and Allan Cormack, CT enables direct imaging and differentiation of soft tissue structures including the liver, lung tissue, and fat. It is especially useful in searching for lesions, tumors, and metastasis. CT reveals the presence, size, spatial location, and extent of the material. CT can also perform the imaging of the head and brain to detect tumors, blood clots, blood vessel defects and other abnormalities, including the nerves and muscles of the eye.
Source:
The 100 Greatest Inventions of All Time by Tom Philbin, New York, Citadel Press, 2003
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