Voxel

Synonyms

Volume element

Definition

A voxel is a measurement of volume in a structure that is to be imaged.

Background

Each voxel represents a defined volume and can be localized by coordinates on a three-dimensional grid. Both CT and MRI scanners image a section of tissue and describe it in a two-dimensional image on the computer screen. Each image is made up of a matrix of two-dimensional cells called pixels. Each pixel represents a volume of tissue, or voxel. The voxel has the same 2-D (x-axis, y-axis) size as the pixel, but the third dimension (z-axis) is equivalent to the slice thickness of the scan. The color (tissue attenuation value) of each pixel is an average of the tissues represented in the voxel. A voxel represents a single data point that is represented on a three-dimensional grid with regular spacing. This data point can consist of a single piece of data or multiple data points. A voxel represents only a single point on this grid, not a volume; the space between each...