Diagnostic nuclear medicine is a type of molecular imaging that uses very small amounts of radioisotopes attached to a targeting molecule (radiopharmaceutical1) to diagnose complex diseases such as cancer. Radiopharmaceuticals are able to show the physiological function of the body rather than just the anatomy. Changes in the biochemical activity of cells often characterises disease. For example, cancer cells multiply at a much faster rate and are more active than normal cells, therefore and often have a high demand for precursors such as amino acids to build proteins.

Radiopharmaceuticals can provide images of what is occurring inside the body at molecular and cellular levels. Depending upon where the patient is in the course of their disease, such a unique insight into the human body may enable physicians to personalise patient care.