Radioactive Tracers

Radioactive tracers – gamma emitters - can be used toimage parts of the body. When introduced into the body, theirprogress can be monitored from outside, and give information abouthow an organ is functioning or to analyse blood circulation forexample.

There are many factors affecting the choice of whichtracer to use for any situation.

  • The radioisotope used should be able to be takenup b the organ in question in a natural way, so must have specificchemical properties.

  • The lifetime of the tracer needs to be matched tothe length of time of the process under study. Choosing thiscorrectly will minimise the amount of tracer used, and the danger tothe patient.

Some tracers and their uses are given in the table.




General body use

Used to measure volumes of body fluids and saltconcentration (sodium, potassium, chlorine)


Used to measure blood volume and differentcomponents (plasma, red blood cells...) and the volume of blood indifferent organs, and to detect internal bleeding


Used to abnalyse absorption of calcium, location ofbone disease and mineral metabolisation

Cancerous tumours

Used to detect locate and diagnose tumours

Heart and lungs

Used to measure the heart blood flow, volume andcirculation. Also used to investigate respiration.


Used to diagnose liver conditions


Used in muscles, especially heart muscles

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