What term describes a 3D volume element in imaging data?

• A. Pixels
• B. Voxels
• C. Dexels
• D. Matrix

Answer: (B)

In 3D imaging data, the unit that represents a small cube of tissue is called a voxel. A voxel is the 3D counterpart to a pixel and carries a single intensity or density value for its tiny volume in space, defined by x, y, and z dimensions. The collection of voxels forms the complete 3D dataset, and voxel size directly affects spatial resolution: smaller voxels capture finer detail but require more data and can raise noise; larger voxels average signals over a bigger volume, reducing resolution but often improving signal strength. Pixels are 2D elements, and terms like dexels aren’t standard, while a matrix is just a data structure holding values, not the volume element itself.