Microcalcifications in breast imaging are tiny white specks of calcium salts. Microcalcifications in clusters, seen on a mammogram, can be the only sign of ductal carcinoma in situ or early invasive cancer, or they can be associated with benign breast changes.

A sample is placed into a concentrated beam of neutrons. Through neutron-capture heavier nuclei become frequently unstable. This artificial radiation decays with a characteristic half-live consisting of alpha- and beta-particles and gamma-rays.

See Neutron Activation Analysis

(ROI) Keyboard controlled identification of a given area of an image for numerical analysis and the area of anatomy being scanned that is of particular importance in the image. This area can also be a volume, than called (VOI) volume of interest.
A ROI can be used for purposes such as calculation of pixel statistics. ROI measurements should be made with the smallest area and away from boarders and edges to avoid partial volume averaging.

The resolution element has the size of the smallest spatially resolved region in an image. It may be anisotropic, e.g. with an asymmetric acquisition matrix or slice thickness, and may be larger than the pixel or voxel.

Concentration determination of trace elements, halogens, lead, arsenic and mercury in pharmaceuticals by neutron activation.

See Neutron Activation Analysis.