MODEL RELEASED. Heart gamma scanning. View of a technician performing a gamma scan of a patient's heart. Several views of the heart are seen on the monitor at lower right. The heart muscle appears as a purple/orange ring or horseshoe shape, depending on the angle of the scan. The heart's chambers appear black or dark blue at the centre of the rings or horseshoes. Gamma scanning is a technique in which a radioactive chemical is injected into the area to be studied, and its emissions detected by a sensitive camera. Here, the heart's health is being monitored to check for any adverse effects of a new drug treatment for AIDS (acquired immune deficiency syndrome).