Medical Use Program to regulate the use of byproduct material in medicine. The review of this program is the subject of the NRC's charge to the IOM.

Byproduct materials include such radionuclides as cobalt-60, iodine-131, iodine-125, and iridium-192, all of which are used for diagnosis and treatment of cancer. They are sources of ionizing radiation and, as such, pose risks to health and safety that sources of nonionizing radiation do not.4 Radiation is ionizing when it dislocates electrons from atoms to produce positive ions and free electrons. (Nonionizing radiation pertains to other types of electromagnetic radiation at wavelengths that do not cause ionization, such as those used in magnetic resonance imaging, microwaves, and radar). Byproduct material is not the only source of ionizing radiation; other sources are radioactive materials that occur naturally or are accelerator produced, and radiation (not materials) produced by x-ray machines and particle accelerators. 5

In examining the existing NRC Medical Use Program, the IOM Committee for Review and Evaluation of the Medical Use Program of the Nuclear Regulatory Commission compared the program not only with the regulation of sources of medically used ionizing radiation other than reactor-generated byproduct material but also with the regulation of medicine in general. The scope of this comparison was occasioned by an awareness of problems among the NRC, Congress, the states, and the regulated community that the entire regulatory system needed to be examined. In particular, a major question for the IOM committee was whether the scientific data on risks associated with reactor-generated byproduct material used in radiation medicine justify the extent to which it is regulated compared to other sources of radiation in medicine and to medicine in general.

ERRORS AND SUCCESSES, BENEFITS AND PROBLEMS OF RADIATION MEDICINE

The Indiana, Pennsylvania, incident—one of the precipitating factors in the NRC's decision to seek an independent review of its Medical Use Program—involved Sara Mildred Colgan, an 82-year-old woman who had worked most of her life as a physical therapist at a home for disabled children before retiring in the mid-1970s. In October 1991, she was diagnosed with cancer.

4  

This is not to imply that there is no controversy or doubt concerning the possible effects of nonionizing radiation.

5  

Naturally occurring and accelerator-produced radioactive materials are collectively referred to as "NARM" to distinguish them from reactor-generated byproduct materials. The term "radionuclide" refers to both NARM and reactor-generated byproducts.



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