Medical Use

The use of radiation and radioisotopes in medicine, particularly for diagnosis, evaluation, and therapy of various medical conditions is a common practice currently. In developed countries about one person in 50 uses diagnostic nuclear medicine each year, and the frequency of therapy with radioisotopes is about one-tenth of this.

• Diagnosis

Nuclear medicine tests use a small amount of radioactive material combined with a carrier molecule. This compound is called a radiotracer. These tests help diagnose and assess medical conditions. They are non-invasive and usually painless.

When a radiotracer is injected into the body, it builds up in certain areas of the body. Radiotracers go to the area of the body that needs to be examined, such as a cancerous tumor or inflamed area. They can also bind to certain proteins in the body.

The most common radiotracer is F-18 fluorodeoxyglucose (FDG). It is just one of many radiotracers in use or in development. FDG is a compound similar to glucose, or sugar. Highly active cancer cells need more energy than normal cells. As a result, they absorb more glucose. An imaging device that detects energy given off by FDG creates pictures that show the location of the radiotracer in the body. Other radioisotopes used in the medical industry are Technetium-99m, Iodine-131, and Molybdenum-99.

Radiotracers are usually given via injection, but they may also be swallowed or inhaled.

Radioisotopes produced at the High Flux Reactor in Petten (The Netherlands) and their applications (Source: NucleairNederland)

• Therapy

Nuclear medicine therapy uses a small amount of radioactive material combined with a carrier molecule. This is called a radiopharmaceutical. Radiopharmaceuticals attach to specific cells and then deliver a high dose of radiation, destroying them.

Nuclear medicine therapies treat cancer and other conditions including Non-Hodgkin’s B-cell lymphoma, neuroendocrine tumors, advanced neuroendocrine tumors affecting the digestive tract and painful tumor metastases in the bones.

Common radiopharmaceuticals used include Radioactive iodine (I-131) therapy to treat thyroid cancer and hyperthyroidism, I-131 MIBG (radioactive iodine labeled with metaiodobenzylguanidine) to treat neuroendocrine tumors, including paragangliomas and pheochromocytomas, and neuroblastoma in infants, Radium-223 dichloride, samarium-153 lexidronam, and strontium-89 chloride to treat painful tumor metastases to the bones and Lu-177 dotatate to treat adult patients with advanced neuroendocrine tumors that affect the digestive tract, known as GEP-NETs. This is also called Peptide Receptor Radionuclide Therapy (PRRT).

• Sterilization

Hospitals use gamma radiation to sterilize medical products and supplies such as syringes, gloves, clothing, and instruments that would otherwise be damaged by heat sterilization. Many medical products today are sterilized by gamma rays from a cobalt-60 source, a technique which generally is much cheaper and more effective than steam heat sterilization. The disposable syringe is an example of a product sterilized by gamma rays. Because it is a 'cold' process, radiation can be used to sterilize a range of heat-sensitive items such as powders, ointments, and solutions, as well as biological preparations such as bone, nerve, skin, etc., used in tissue grafts.

The benefit to humanity of sterilization by radiation is tremendous. It is safer and cheaper because it can be done after the item is packaged. The sterile shelf life of the item is then practically indefinite provided the package is not broken open. Apart from syringes, medical products sterilized by radiation include cotton wool, burn dressings, surgical gloves, heart valves, bandages, plastic and rubber sheets, and surgical instruments.