ABSTRACT
CH A P T E 7 Radiation Protection in Radiation Oncology Raymond K. Wu Department of Radiation Oncology & Cyberknife, University of Arizona Cancer Center, Phoenix, Arizona, USA
Richard J. Vetter Mayo Clinic, Rochester, Minnesota, USA
R adiation oncology is the sub-discipline of oncology that focuses onthe use of radiation to treat cancer. This medical specialty is concernedwith prescribing radiation to treat disease (radiation therapy) as opposed to the medical specialty of radiology where radiation is used to diagnose disease. Thus, the quantum energy of the radiation and the absorbed doses applied in radiation therapy are orders of magnitude greater. Radiation therapy is applied to the human body in several different ways to treat cancer. The most common method is directing a beam of radiation on the tumor, i.e., the target tissue. Beams of different dimensions, shapes, and intensities are directed on the lesion from various directions to maximize dose to the lesion and to minimize dose to normal tissues. In curative radiation therapy the objective is to eradicate the tumor while sparing critical structures and minimizing damage to other healthy tissues following strict guidelines. This beam of radiation is most often generated by a powerful X-ray machine called a linear accelerator. Other types of machines can also generate beams of radiation for therapy and are discussed below. While no longer commonly used in countries with more resources, teletherapy machines using high activity 60Co sealed source is used in some practices around the world to deliver the beam of radiation. In developed countries 60Co is also used in a self-shielded device called the Gamma Knifer to treat various lesions of the brain. Another form of radiation therapy that uses smaller quantities of various radionuclides to treat cancer is called brachytherapy and will be described below. In a modern radiation oncology department, there are many potential safety concerns. We will focus only on those in which radiation is the primary contributing factor.
