History of computed tomography

[3][4][5][6][7][8][9][10][11] It was not widely used until the 1930s, when Dr Bernard George Ziedses des Plantes developed a practical method for implementing the technique, known as focal plane tomography.

In October 1963, William H. Oldendorf received a U.S. patent for a "radiant energy apparatus for investigating selected areas of interior objects obscured by dense material".

[15] In 1937, Polish mathematician Stefan Kaczmarz developed a method to find an approximate solution to a large system of linear algebraic equations.

[citation needed] In 1956, Ronald N. Bracewell used a method similar to the Radon transform to reconstruct a map of solar radiation.

[clarification needed][21] In his landmark 1961 paper, he described the basic concept later used by Allan McLeod Cormack to develop the mathematics behind computerized tomography.

In October 1963, Oldendorf received a U.S. patent for a "radiant energy apparatus for investigating selected areas of interior objects obscured by dense material," for which he shared the 1975 Lasker Award with Hounsfield.

[27] Conventional focal plane tomography remained a pillar of radiologic diagnostics until the late 1970s, when the availability of minicomputers and the development of transverse axial scanning led CT to gradually supplant as the preferred modality of obtaining tomographic images.

Scanners now produce images much faster and with higher resolution enabling doctors to diagnose patients more accurately and perform medical procedures with greater precision.

The first commercially viable CT scanner was invented by Sir Godfrey Hounsfield in Hayes, United Kingdom, at EMI Central Research Laboratories using X-rays.

This scanner required the use of a water-filled Perspex tank with a pre-shaped rubber "head-cap" at the front, which enclosed the patient's head.

Allan McLeod Cormack of Tufts University in Massachusetts independently invented a similar process, and both Hounsfield and Cormack shared the 1979 Nobel Prize in Medicine for their contributions to the development of CT.[30] The first computed tomography (CT) system capable of producing images of any part of the human body without the need for a cumbersome "water tank" was the Automatic Computerized Transverse Axial (ACTA) scanner, designed by Dr. Robert S. Ledley, DDS, at Georgetown University.

This revolutionary machine was equipped with 30 photomultiplier tubes as detectors and was capable of completing a scan in just nine translate/rotate cycles, significantly faster than the EMI-Scanner.

Georgetown University's prototype of the ACTA scanner caught the attention of the pharmaceutical giant Pfizer, which acquired the rights to manufacture it.

Remarkably, this computer functioned with a mere 64 KB of memory and a 5 MB hard disk, which held both the operating program and the acquired raw data.

The scanner counts individual x-ray photons that pass through a patient and discriminates their energy, increasing the detail supplied to the reader.