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What is nuclear medicine?

Nuclear medicine a branch of medical imaging. It involves giving small amounts of radioactive materials (radiotracers) to patients in order to scan the body from the inside using special cameras that detect radiation and create images of the inside of the body. It has been described as the reverse of radiology, which uses radiation such as X-rays to scan the body from the outside.

It can also be used for treatment in certain situations. For example, radioactive iodine I-131 therapy can be used to treat cancers and certain conditions affecting the thyroid gland.

What does nuclear medicine involve?

Radiotracers can be swallowed, delivered by injection, or breathed in as a gas. They eventually accumulate in the part of the body being examined. The radiation they emit is traced by special cameras, which produce images that allow the doctor to examine what is happening inside the patient in fine detail. They provide information, such as what is happening on a molecular level, which is impossible to obtain by other means.

Why is it done?

Nuclear medicine imaging is done to allow the doctor to visualise the structure and function of organs, tissue, and bones inside the body, including:

• The heart – e.g. assessing the damage after a heart attack; diagnosing coronary artery disease; evaluating heart function, etc.
• The lungs – e.g. scanning for respiratory or blood flow problems; detecting organ transplant rejection, etc.
• Bones – e.g. detecting fractures, arthritis, infection, metastatic bone disease; identifying sites for biopsy; evaluating prosthetic joints, etc.
• The brain – e.g. investigating abnormalities; detecting early onset Alzheimer’s, etc.
• The kidneys – detecting urinary tract obstructions; analysing kidney blood flow and function, etc.
• Other – identifying bleeding in the bowel; measuring thyroid function; identifying gallbladder problems, inflammation, etc; locating infections, etc.

It is also used in testing for and treating cancer in various parts of the body, including in determining the stage and spread of cancer, evaluating the response to treatment, and even in treating certain tumours and certain forms of lymphoma.

Preparation for nuclear medicine

As with most scans, you will have to remove jewellery beforehand. Inform your doctor and technologist if there is any chance you might be pregnant or if you are breastfeeding, and also let them know about any allergies or medical conditions you have. Your doctor may give you instructions about eating and drinking in the 24 hours before the exam, depending on the type of test.

What to expect during the test

Nuclear medicine is generally non-invasive and painless (although if the radioactive material is injected, the patient will experience the usual discomfort associated with injections). Depending on the area being scanned and the radiotracer used, scanning may be done within seconds or after a few days – it depends how long the radiotracer takes to reach its destination.

The type of camera or scanning equipment used depends on the nature and objective of the test. It may be done in the space of 20 minutes or may take several hours to complete. Some scans are conducted over several days.