History of Radiology

CT Scanning

Sir Godfrey Hounsfield

CT was invented in 1972 by British engineer Godfrey Hounsfield of EMI Laboratories in England. Hounsfield was later awarded the Nobel Peace Prize and honoured with a Knighthood for his contributions to medicine and science. CT combined x-ray images with a computer. If you took many x-rays of the same area, at slightly different angles, a computer could put the information from the x-rays together to create a cross-sectional image.

Godfrey Hounsfield made a prototype in 1971 and the following year tried it out on a patient. The CT scanners for clinical use were first installed in 1975. The original systems were dedicated to head scanning but whole body scanners with larger patient openings became available in 1976. 30,000 CT Scanners are now installed worldwide. The first CT scanner developed by Hounsfield in his lab at EMI took several hours to acquire the raw data for a single scan (slice) and took days to reconstruct a single image from this raw data.

The latest multi-slice CT systems can collect up to 4 slices of data in about 350 ms and reconstruct a 512 x 512-matrix image from millions of data points in less than a second. An entire chest (forty 8 mm slices) can be scanned in five to ten seconds using the most advanced multi-slice CT system.

During its 25-year history, CT has made great improvements in speed, patient comfort, and resolution. As CT scan times have got faster, more anatomy can be scanned in less time. Faster scanning helps to eliminate artifacts from patient motion such as breathing or bowel movements. The new scanners provide excellent images of diagnostic quality at low doses of radiation.

MRI Scanning

The first clinical use of MRI took place in Nottingham University Hospital in 1967. The images then were of poor quality and could not be used for clinical medicine. With the advances in the computer and magnet technology the image quality improved. In the early 1980s The Clinicians were impressed by its ability to visualize abnormalities in the brain specially in the posterior fossa of the brain. CT scans by this time had established as an important diagnostic tool in the head and body imaging.CT scan uses X-Rays unlike MRI which uses magnetism.

Over the next few years, MRI became a supplementary modality to CT specially for investigating the Brain and spinal cord. Pictures from the chest and abdomen were not of diagnostic quality as they were blurred from respiratory and heart motion. With the introduction of high field magnets in the mid 1980s, came faster scan times and better techniques. Soon the superiority of MRI over CT scan was established. The improved hardware and software in computers gave MRI the ability to produce good quality images from all parts of the body.

Today MRI is the imaging modality of choice for most parts of the body. The images of the spine, musculoskeletal system, neck and mediastinal structures are of excellent quality. Recently the reduction of scanning time down to milliseconds allow for MRI fluoroscopy which shows movement of organs and structures in real time. This may be used in interventional radiology.

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Contents

History of Radiology

CT Scanning

MRI Scanning