Nuclear medicine uses very small amounts of unsealed radioactive materials (radiopharmaceuticals) to diagnose and treat disease.
Nuclear medicine imaging is unique in that it provides doctors with information about both the anatomy of the body and its physiology (function).
Nuclear medicine tests are safe and painless. They allow quick and accurate diagnoses of a wide range of conditions and diseases, such as heart disease, blood clots in lungs, bone infections, sports injuries, tumours and cancer metastasis (spread).
In addition, nuclear medicine therapy may be used to control, and in some cases cure, a range of conditions such as thyroid cancer, overactive thyroid, and bone pain caused by cancer metastasis.
Nuclear medicine imaging is used for detecting a range of conditions including:
- Irregular or inadequate blood flow to tissues
- Blood cell disorders and inadequate functioning of organs such as thyroid and pulmonary function deficiencies
Current nuclear medicine techniques include:
- Positron Emission Tomography (PET)
- Single Photon Emission Computed Tomography (SPECT)
- Cardiovascular imaging
- Bone scanning
Positron Emission Tomography (PET)
PET and SPECT imaging are similar techniques in that they both utilise gamma rays given off by the radiopharmaceutical that is injected.
PET utilises short-lived radioactive isotopes; the PET camera detects the gamma rays given off at the site where a positron emitted from the radioactive substance collides with an electron in the tissue. Through a number of stages the PET camera enables the gamma rays to be converted to electrical signals that are processed by a computer to generate images; a series of many thin “slice” images of the body can then be assembled into a three dimensional representation of the patient’s body.
PET provides images of blood flow or other biochemical functions. PET is increasingly used in the detection and staging of cancers, particularly in metastatic spread, where glucose metabolism enables metastases to be readily identified
Through the use of PET scanning, the use of nuclear medicine for diagnosis of cancer and for identifying metastatic spread is increasing rapidly.
In addition, nuclear therapy is used to treat some cancers in cases where other therapeutic options may have been exhausted.
Single Photon Emission Computed Tomography (SPECT)
SPECT uses radioactive isotopes that are longer living than those for PET and emit single rather than double gamma rays. SPECT is a “mature” technology in that is has been available for many years and is widely available to the Australian community.
The major cardiac imaging technique is the myocardial perfusion (stress thallium) study, whereby the patient undergoes two studies one with and one without exercise; the before and after images enable changes in blood flow to the heart to be assessed. This is an important test to detect blocked arteries or arterioles in the heart.
Nuclear Medicine Specialty
In Australia, nuclear medicine is provided by recognised specialists in nuclear medicine. Nuclear medicine is an advanced specialty in that the Advanced Training Program is undertaken as specialty training of either the Royal Australasian College of Physicians (RACP) or the Royal Australian and New Zealand College of Radiologists (RANZCR).
Nuclear medicine specialists will thus have completed a further 7-8 years of training after they have qualified as medical practitioners (a total of approximately 15 years’ university and post graduate training).
There are currently approximately 450 credentialled specialists in nuclear medicine in Australia who deliver nuclear medicine services in approximately 200 sites across Australia. The most common studies are bone scans, myocardial perfusion studies, lung perfusion studies and thyroid scans, which comprise 80 per cent of all studies.
The AANMS is the main organisation in Australia representing the specialty of nuclear medicine. The AANMS takes a major role in the promotion and advancement of the clinical practice of nuclear medicine and is responsible for accreditation of training sites.