What defines a voxel in a computed tomography (CT) image?

A voxel is defined as a three-dimensional unit of image data in computed tomography (CT) imaging. In the context of CT, a voxel represents a specific volume in the scanned area, similar to how a pixel represents a specific area in a two-dimensional image. Each voxel contains information about the composition of the tissue within that volume, including density and attenuation characteristics that contribute to the creation of the final image.

Voxel data is critical because it allows for the reconstruction of the three-dimensional anatomy of the patient, providing more detailed information compared to traditional two-dimensional imaging techniques. This three-dimensional perspective is essential for accurately diagnosing and evaluating conditions within the body.

The other options do not accurately describe a voxel. A two-dimensional shape relates more to pixels, which are the building blocks of flat images rather than three-dimensional data units. The width of the beam in a scan pertains to the physical characteristics of the CT scanner and does not define what a voxel is. Lastly, the distance between adjacent slices refers to slice thickness and spacing in scanning protocols, rather than the volumetric concept of a voxel itself.