Nuclear medicine is an imaging modality that involves injection, inhalation or injection of radioactive tracers to visualize various organs. The tracer or radiopharmaceutical is produced through addition of a radioactive isotope to a pharmaceutical specific to the organ being imaged. The radioactive tracer emits gamma radiation, which is then imaged using a gamma camera.
The gamma camera consists of a radiation sensitive crystal which detects the distribution of the tracer within the patient's body. The information is converted to a digital format to produce a two or three dimensional image on a screen. The latest generations of gamma camera are hybrid machines including a CT to allow for fusion of Nuclear Medicine and CT images.
The field of Nuclear Medicine also incorporates therapy procedures. A high dose of therapeutic radiation is delivered through administration of a radiopharmaceutical specific to the diseased target organ. This is of benefit to treat cancer or over functioning thyroid gland.
Common Clinical Applications
- Bone scan; to assess metabolic activity of the bones. Commonly used for oncology staging, arthritis, fractures.
- Myocardial Perfusion scan; to compare the blood flow to the myocardium at exercise and rest allowing for differentiation of ischaemia and infarction.
- Renal scan; to determine the perfusion and drainage of the kidneys and allow for calculation of differential function.
- Lung scan (VQ); to allow for comparison of ventilation and perfusion of the lungs to diagnose pulmonary embolism.
- Thyroid scan; to assess the appearance and function of the thyroid gland.
- Pregnancy status must be established prior to procedure. Performance of a Nuclear Medicine study on a pregnant woman must be clinically justified, with the administered dose minimized.
- Breast feeding women may need to cease breast feeding dependent on the procedure being performed. This is due to excretion of the radiotracer in the breast milk.
- Children are particularly radiosensitive; therefore non radiation imaging modalities such as ultrasound and MRI should be utilized if possible. When performing Nuclear Medicine studies on pediatric patients the radioactive dose is scaled according to the patient's weight.
- To aid excretion of the tracer via the urinary tract, the patient may be instructed to remain well hydrated and urinate frequently to reduce radiation dose.
- Patients undergoing therapy procedures will be given specific instructions regarding radiation safety.