False-colour scintigram (gamma camera scan) of a median (profile) section through the human skull, showing a normal brain (the central red area). The image is obtained by recording the distribution of radioactivity (emitted by a previously-injected radionuclide) according to the light given off by a scintillator (a gamma camera) as it is struck by radiations of different intensities. Gamma camera scans provide information on the function of organs and tissues in the body (as opposed to the structural view afforded by other techniques such as x-rays, CAT & NMR scans). Here, blood flow in the brain is being assessed with respect to potential vascular disease (ischaemia). Compare with M180/003, same technique & section