How It Works

In nuclear medicine, medical professionals inject a tiny amount of a radioisotope—a chemical element that produces radiation—into a patient’s body. A specific organ picks up the radioisotope, enabling a special camera to take a detailed picture of how that organ is functioning. For example: 

• Myocardial perfusion imaging maps the blood flow to the heart, allowing doctors to see whether a patient has heart disease and determine the most effective course of treatment.
• Bone scans can detect the spread of cancer six to 18 months earlier than X-rays.
• Kidney scans are much more sensitive than X-rays or ultrasounds in fully evaluating kidney function.
• Imaging with radioactive technetium-99 can help diagnose bone infections at the earliest possible stage.

These kinds of diagnostic procedures involve very small amounts of radioisotopes. In higher doses, radioisotopes also help treat disease. For example, radioactive iodine’s widespread use in therapy for thyroid cancer results in a lower recurrence rate than drug therapy. It also avoids potentially fatal side effects, such as the destruction of bone marrow.

Sealed sources of radiation placed inside the body, or radiation directed from external sources, are effective in treating various cancers. Nearly half of all cancer patients in the United States receive radiation treatment at some point in their therapy.

Hospitals also use radiation to sterilize materials, thus helping to prevent the spread of diseases. Exposing these materials to radiation does not make them radioactive.


CT Scans Reduce Need for Exploratory Surgery

A 2009 report from the National Council on Radiation Protection and Measurements (NCRP) found a dramatic increase in the use of nuclear medicine since the 1980s, especially computed tomography (CT) scans. These scans help guide treatment of car-accident injuries, cancer, blood clots in the lungs and many other conditions. Approximately 68 million CT scans were performed in the United States in 2006, according to the NCRP. ¹

CT and other medical imaging procedures have largely eliminated the need for exploratory surgery, leading to a lower risk of surgery-related complications and shorter hospital stays, said Cynthia McCollough, Ph.D., a professor of radiological physics at the Mayo Clinic. Improved technology enables CT scanners to tailor the radiation dose to the specific exam type and individual. As a result, the average dose per CT exam has fallen by a factor of two or three since the early 1980s, McCollough said. ²  

¹“Medical Radiation Exposure of the U.S. Population Greatly Increased Since the Early 1980s,” press release, National Council on Radiation Protection and Measurements, March 3, 2009.)

² “Average radiation exposure of the US population requires perspective and caution,” American Association of Physicists in Medicine, press release, March 3, 2009.)