A unit of X‐ray attenuation used for computed tomography scans as a measurement of bone density. Each pixel is assigned a value on a scale on which air is 1000, water 0, and compact bone +1000.
In computed tomography (CT), a number or value that represents the attenuation of x-rays through a voxel (volume element) in the body and is assigned to the corresponding pixel (picture element) on the image. This number is relative to the standard, which is the absorption of x-rays in water on a scale of +1,000 to — 1,000. It is also known as a CT unit.