Protection and measurement in radiation therapy.

In radiation therapy, unlike most other applications involving radiation, the intention is to deliver high doses of radiation to diseased tissue, constrained by the effects of radiation to healthy tissue. With regard to patient exposure, the radiation protection framework of justification, optimization, and limitation is a direct part of the prescription process of radiation therapy. Staff and public exposures are typically far below occupational maximum permissible exposures. However, a number of other issues arise in radiation therapy that fall into the category of radiation protection. After an historical review, this paper discusses several contemporary and emerging concerns within radiation therapy, including fetal dose, secondary malignancies, and dose to implantable devices, all of which involve accurate dose assessment outside the intended treatment volume. Other concerns include quality and safety, molecularly based disease assessment and treatment, and other novel treatment strategies. The paper ends with a discussion of the interplay between best practices and regulatory oversight.