Tracers and markers in medicine
The tracers used in medicine are complex organic molecules specifically chosen for their affinity for the organ under examination. These molecules are ‘marked’ by the presence of a radioactive nucleus, and are often injected intravenously. On these skeletal scans, we can see the areas where a diphosphate marked with technetium 99 has built up, indicating the possible presence of metastasis. This particular marker is very popular in gamma scintigraphy.