It was introduced in the early 1970s,
and Allan Cormack and Godfrey Hounsfield shared the Nobel Prize in Physiology
and Medicine in 1979 for its development.
Bones show up clearly on x-ray images,
but soft tissues do not.
Computed Tomography (CT) images provide
a “cross-section” view that displays a thin slice of the body.
The x-ray tube and detectors rotate around
the patient.
The scanner records the x-ray absorption
by the patient's body.
A CT image is composed of pixels, whose
brightness corresponds to the absorption of x-rays in a thin rectangular
slab of the cross-section, which is called a “voxel.”
Since the CT scan requires so many x-ray
exposures, the amount of radiation used to make a CT scan is typically greater
that used to make a traditional x-ray.
b
