What artifact occurs when multiple tissues with different linear attenuation coefficients are in the same voxel?

The phenomenon described occurs when a single voxel contains a mix of tissues that have different linear attenuation coefficients. This results in an averaging effect where the contribution of each tissue type is combined, leading to a loss of image detail and potential misrepresentation of the tissues' actual characteristics. This is known as Partial Volume Averaging.

In computed tomography, each voxel represents a three-dimensional volume, and if it encompasses different types of soft tissues, the resulting attenuation value captured in the CT image will not accurately reflect any single tissue type. Instead, it appears as an average, which can blur the interface between tissues and reduce diagnostic accuracy. For example, where muscle and fat meet, they will produce a value that may not distinctly reflect the true density of either tissue, thus creating an artifact.

Understanding Partial Volume Averaging is critical for radiologists and technologists, as recognizing this artifact allows for improved imaging techniques or adjustment in scan protocols to minimize its effects. Other options, such as aliasing, beam hardening, and image noise, refer to different types of artifacts or issues that occur within imaging but do not directly address the phenomenon of mixed tissue attenuation within a voxel.