The CT scanner was invented by an engineer at a British music company
In 1972 Godfrey Hounsfield, an engineer at the British firm EMI, unveiled a machine that fired X-rays through a slice of the head and let a computer rebuild a cross-section. Three years later EMI had a version for the whole body. Hounsfield shared the 1979 Nobel Prize in medicine with the physicist Allan Cormack.
Seeing inside living people has become routine. More than 5 billion imaging studies had been carried out worldwide by 2010, and in 2006 medical scans made up about half of all ionizing radiation Americans received. Most techniques are noninvasive, meaning nothing enters the body. The hardware leans heavily on the chip industry, from image sensors to signal processors, and in 2015 some 46 million medical imaging chips shipped, worth 1.1 billion dollars.
Plain X-ray pictures were the first modern imaging method and remain common because they are cheap, sharp and, for some uses, lower in dose than three-dimensional scans. A wide beam passes through the body and dense tissue such as bone blocks it. Fluoroscopy keeps a weaker beam running to produce moving pictures, often with barium, iodine or air to outline organs as they work. Its receiver evolved from a glowing screen to a large vacuum tube coated with caesium iodide that reflected the image in a mirror, and finally to a television camera.
CT and MRI see different things. CT depends on tissue dense enough to stop X-rays, so soft organs show poorly, while MRI listens to hydrogen in water and gives excellent soft-tissue detail without ionizing radiation. MRI does carry risks from heating by radio waves and from implants such as pacemakers, which scanner designs and protocols tightly control. Combining several MRI sequences, an approach called multiparametric imaging, helps distinguish tissues in organs such as the prostate and liver.
Pictures made with ordinary light count too, as in dermatology and wound care. Radiologists usually read the images, though trained radiographers increasingly do so. Digital medical image processing was inducted into the Space Technology Hall of Fame in 1994.
Source: Medical imaging
