Uses of Nuclear Radiation

Nuclear radiation is used in two ways in medicine:

- as a tracer (also see PET scans) - Radioactive isotopes and radioactively labeled molecules are used as tracers to identify abnormal bodily processes.

This is possible because some natural elements tend to concentrate in certain parts of the body: iodine in the thyroid, phosphorus in the bones, potassium in the muscles.

When a patient is injected with a radioactive element, a special camera can take pictures of the internal workings of the organ.

- as therapy - for example a medical treatment for cancer (radiotherapy). A high radiation dose causes cell death.  

Radioactive Tracer
Radioactive Treatment
Type of treatment Diagnostic Therapy
Aim of treatment To investigate the function of a part of the body by labelling a biologically useful compound with radioactive atoms To destroy malignant tumours with a high dose of radiation that will result in cell death
Type of dose administered Minimal dose to patient Maximum dose to affected part, minimum dose to surrounding tissue
Type of radiation used Gamma Rays Gamma Rays
Example of substances used Pure gamma emitters such as technetium 99m Pure gamma emitters such as cobalt 60 and caesium 137
Half life Short ( about 6 hours) Long (typically 5.3 years)
Treatment Radioactive substance is injected into the patient making him/her mildly radioactive. The nuclear radiation emitted is then 'viewed' using a gamma camera A strong radioactive source is used to deliver nuclear radiation to the affected part. If this is from outside the body the patient doesn't become radioactive BUT if it is from an implanted source (like a radioactive wire inserted into the tumour) the patient does become radioactive and usually has to stay in hospital until the source is removed.
What equipment is used? The 'hardware' in the hospital (a gamma camera) does not deliver radiation but detects it.  The hardware in the hospital (a LINAC - linear accelerator or Cobalt 60 unit) produces ionising radiation which is 'fired' at the patient.
How does the patient feel afterwards? After the investigation the patient does not feel unwell  After the treatment the patient may well feel unwell: sickness, nausea, exhaustion.
Is the patient radioactive afterwards? After the investigation the patient is still mildly radioactive and may need to avoid contact with pregnant women and young children for a couple of days to minimise any risk to them. He/she will be told not to use public transport or to go to public places to avoid inadvertent contact with such individuals. After the treatment the patient is NOT radioactive. He/she may see other people straight away (although feeling unwell may not wish to).

LOJ (February 2001) - revised February 2003