抄録
Ionizing radiation has long been indispensable in medicine. Such medical exposures can broadly be divided into two categories, namely, therapeutic exposures and diagnostic exposures. On one hand, therapeutic exposures generally occur at high dose and/or high dose rate, in which health effects of main concern are tissue reactions (formally called deterministic effects) and second cancer. Of these, mounting epidemiological evidence for tissue reactions has attracted particular attention to circulatory disease and cataracts. Diagnostic exposures, on the other hand, occur at relatively low dose and/or low dose rate, where cancer is the major health effect of concern. Epidemiological evidence from diagnostically exposed populations is still subject to uncertainties in dose (e.g., lack of individual doses) and potential biases (e.g., confounding by indication and reverse causation), which render direct risk estimation of diagnostic exposures unreasonable. This raises the need for the extrapolation from epidemiological evidence in other populations exposed to high dose and/or high dose-rate radiation. From radiation protection viewpoints, recent discussions include individual risk estimation, and individual radiation responses. This review paper provides a brief overview of recent topics in epidemiology and risk estimation for medical exposures.
