ABSTRACT
The National Cancer Institute estimates that half of all US cancer patients now are treated with ionizing radiation in radiation therapy (or radiotherapy), while enormous numbers of lifesaving medical exams (see Chapters 5 and 6) make routine use of small doses of radiation. In spite of this, a widespread perception exists that any amount of radiation represents a serious hazard. The truth is complicated: ionizing radiation can be used to diagnose and treat cancer and other illnesses, and yet itself can be a carcinogen (cancer-causing agent), or cause an illness called radiation sickness. In this chapter, we review the risks and benefits involved in using ionizing radiation in medicine. We will see that the radiation doses used in medical imaging have been lowered over time, until the benefits of proper medical care almost always outweigh the risk. In fact, the compromise between risk and benefit in modern medical imaging is more favorable than that presented by many common drugs, few of which are absolutely complication-free and some of which cause lethal reactions in an extremely small number of cases.
