voxel
Pronunciation: VOX-el
A three-dimensional pixel representing the smallest unit of volume in digital imaging, containing specific density or intensity values.
Full Definition
A voxel (volume element) is the three-dimensional equivalent of a pixel, representing the smallest distinguishable volume element in digital medical imaging. Each voxel contains specific attenuation, signal intensity, or radiotracer uptake values depending on the imaging modality. In CT imaging, voxels contain Hounsfield unit values; in MRI, they contain signal intensity measurements; and in nuclear medicine, they represent radiotracer concentration. The size of voxels directly affects image resolution, with smaller voxels providing better spatial resolution but potentially increasing noise. In oncologic imaging, voxel analysis is fundamental for quantitative assessments, treatment planning, and advanced imaging techniques such as perfusion analysis and radiomics. Modern imaging systems allow for isotropic voxels, where all three dimensions are equal, enabling high-quality multiplanar reconstructions.
Usage
Usage note: Distinguish from pixel, which is two-dimensional.
In Context
- "The reconstruction algorithm creates isotropic voxels measuring 0.5mm in all dimensions." — Technical imaging specifications
- "Each voxel in the PET dataset represents the average radiotracer uptake within that volume." — Nuclear medicine quantification