Nuclear Medicine

Nuclear medicine involves imaging parts of the body down to the cellular level. Unlike other imaging methods, such as x-rays, CT scans, or MRIs that use an external source to create the image (Read about "X-rays" "CT Scan - Computerized Tomography" "MRI - Magnetic Resonance Imaging"), nuclear medicine uses an internal source. Nuclear medicine can also be used to treat certain types of cancer and other diseases.

Nuclear medicine uses what are called radiopharmaceuticals. They are also sometimes referred to as probes. They consist of very small amounts of radioactive materials combined with a medicine, thus the name radiopharmaceutical. The pharmaceutical part of the probe is designed to go to a specific part of the body where the radioactive part of the material emits radiation and allows a special camera, such as a gamma camera or a positron emission tomography (PET) scanner to see what is happening, down to the cellular level. (Read about "PET - Positron Emission Tomography")

The Society of Nuclear Medicine (SNM) says that the amount of radioactive material that is used is minute, generally less than one-tenth of a million of an ounce. SNM also says that the risk of a reaction to the material is two to three incidents per 100,000 procedures. By comparison, x-ray contrast elicits two to three thousand reactions per 100,000 procedures, according to SNM.

According to the Society of Nuclear Medicine and Molecular Imaging (SNMMI), most of the time the radiopharmaceutical is injected. It might also be swallowed or inhaled, according to SNM.

Two types of nuclear medicine scans are positron emission tomography (PET) and single-photon emission computed tomography (SPECT).

PET scans use the radiopharmaceutical FDG. FDG is similar to glucose and goes to places in the body that are active and using a lot of glucose. For example, cancer cells will show higher levels of FDG because they are more active than normal cells. However, cells in the brain that are affected by dementia will have less FDG show up. (Read about "The Brain" "Dementia")

SPECT involves injecting a radiopharmaceutical designed to accumulate in a specific organ or type of cell. A gamma camera then is used, along with a computer, to build a three-dimensional image of how the probe is distributed, showing blood flow and how the organs are functioning. SNMMI says SPECT studies can be combined with CT scans.

With the ability to provide a clear picture of blood flow, nuclear medicine can help diagnose heart disease and provide a clear picture of how blocked an artery might be and how the heart is functioning. (Read about "Coronary Heart Disease") It also has an impact on cancer treatment (Read about "Cancer Treatments"), showing if some treatments are having an effect.

Nuclear medicine itself can be a treatment for some cancers. Nuclear medicine has been treating thyroid cancer for over 50 years. (Read about "Thyroid Cancer") Iodine collects in the thyroid, so radioactive iodine is given to the patient and the radioactive material is absorbed by cancer cells there and they are destroyed.

SNMMI says so-called targeted radionuclide therapy (TRT) can also be used to treat other forms of cancer such as non-Hodgkin lymphoma. (Read about "Lymphoma")

If you undergo a nuclear medicine procedure, your doctor will tell you what you need to do, both before and after. SNM says you will probably want to drink lots of fluids after the procedure to flush the excess radioactivity out of your body. If you are pregnant or breastfeeding, be sure to talk to your doctor about these issues before the procedure.