ABSTRACT
This chapter reviews the stochastic effects of radiation on the induction of carcinogenesis as a function of dose, as this is the major concern with regard to the safety of radiation workers as well as in the management of patients undergoing diagnostic procedures and radiation therapy. The aim of radiation epidemiology is to identify, understand, and quantify the risk of cancer in a population when it is exposed to medical, occupational, or environmental radiation. The LNT hypothesis states that "above the prevalent background dose, an increment in dose results in a proportional increment in the probability of incurring cancer of ˜0.005" per mSv of dose". Since the biological system can repair a significant part of radiation damage for low-intensity (chronic) exposures, it is assumed that the risk should be half for low doses and when radiation is delivered at low dose rates. This is referred to as the dose and dose rate effectiveness factor (DDREF).
