Radioactive tracer

A radioactive tracer is introduced into the body, for example by swallowing it or injecting it. It is usually incorporated into a substance that follows a particular biological pathway or collects in a particular organ. Detectors outside the body record radiation coming from different positions.

For detection, a radioactive tracer in the body emits radiation that can be detected from outside, helping to locate a tumour or investigate what is happening inside the body. For treatment, beams of gamma rays are directed at a tumour to damage or kill cancer cells. The treatment is planned to limit exposure of surrounding healthy tissue.

Gamma rays can be used in medical imaging with a radioactive tracer introduced into the body. A scanner detects gamma rays coming from the tracer and maps where it has collected, helping reveal activity inside the body. This is different from shining an X-ray beam through the body.

To explore an internal organ, a patient may be given a small amount of a radioactive tracer. The tracer can be attached to a compound that travels to a particular part of the body. As it moves or is taken up by tissue, it emits radiation.