In a voxel that includes various tissue types, what will be displayed by the pixel in the reconstructed image?

In computed tomography, a voxel represents a three-dimensional pixel that corresponds to a specific volume of tissue in the body, which can contain multiple types of materials with different attenuation properties. When the CT scan is performed, each voxel is assigned a CT number (or Hounsfield unit) that reflects the average attenuation of X-rays as they pass through the tissue.

When multiple tissue types are present within a single voxel, the pixel in the reconstructed image displays the average CT number of all the tissues represented in that voxel. This average is calculated based on the contributions from each type of tissue, weighted by the volume that each tissue occupies within the voxel. As a result, the displayed pixel does not represent any single tissue type exclusively (like the maximum or minimum CT number) but instead summarizes the attenuation characteristics of the mixed materials.

This averaging process is fundamental for accurately representing the composition of the scanned area, allowing radiologists and medical professionals to interpret images based on the overall profile of the tissues, rather than potentially misleading singular values.