Nuclear medicine

What is nuclear medicine?

Nuclear medicine is a medical specialisation which uses radioactive substances in order to investigate organ metabolism and for other therapeutic purposes.

For diagnosis, a radioactive tracer (a radioactive isotope linked to a physiological substance) is administered to the patient, most often intravenously. The radioactive element is carried by the physiological substance to the organ that needs to be examined. Depending on its metabolism, more or less radiation will be detected in the organ. Any potential illness will alter this radiation level.

After a waiting period (which varies from immediately to up to several hours after the injection), images are taken using a gamma camera (scintigraphy, SPECT/CT) or PET/CT (positron-emission tomography linked to scanner). The choice of equipment and radioactive substance used depends on the type of examination required.

What are the risks?

Radiation protection is taken very seriously within nuclear medicine and equipment and materials are regularly reviewed in order to achieve the best possible results using the least amount of radiation. The dose given to a patient during a nuclear medicine examination is comparable to that of a radiology examination. A team of radiation protection experts will monitor the doses.

Care for pregnant women:

Radiological examinations and MRI scans should be avoided.

If breastfeeding, women should express and dispose of breastmilk for 24 to 48 hours after the scintigraphy. A minimal-dose pulmonary scintigraphy can be used to detect pulmonary embolisms in pregnant women.

Imaging techniques

Scintigraphy

The device records the gamma rays emitted by the patient to create functional images. Activity curves can be generated, for example to map kidney function or compare the activity of a body part on the left with a body part on the right. This is often used to examine stress fractures or bone disorders. Two radioactive tracers are used to examine the lungs; one is inhaled and the other injected. This technique is used to examine lung function before an operation, in cooperation with a pneumologist, and to detect pulmonary embolisms. To confirm a diagnosis of Parkinson’s disease, a cerebral scintigraphy (Datscan) may be carried out at the request of a neurologist. In endocrinology, a scintigraphy can be carried out on the thyroid or parathyroid glands. It is the preferred examination for hormonal issues, or to investigate thyroid or parathyroid nodules. In the case of symptoms that can suggest coronary artery disease (feelings of suffocation, chest pain, shortness of breath), a cardiac scintigraphy is indicated. For this examination, a cardiac stress test is carried out with a cardiologist once the radiotracer is administered. The result shows the activity of the cardiac muscle and allows doctors to diagnose an ischaemia or infarct.

PET scan

A PET/CT scan is used for oncological, cardiological and neurological examinations and to investigate sources of infection. In oncology, this technique can be used to confirm the presence of a cancer. As the patient’s whole body is examined, it can also detect tumour cells present in other organs (metastasis). With the PET/CT scan, quantitative values can be obtained and used to track tumour cells, in order to determine if a treatment is working and evaluate if the cancer is improving.

From a therapeutic point of view, nuclear medicine uses radioactive pharmaceuticals to destroy diseased cells. A pre-treatment scintigraphy or PET/CT scan ensures the radiation correctly targets the diseased cells. Afterwards, the patient is administered radioactive pharmaceuticals that are specific to the cells that need to be destroyed. Some therapies can be carried out as outpatient procedures and the patient can leave the nuclear medicine centre after the injection.