Biological Effects of Ionizing Radiations

The use of ionizing radiation in medicine followed soon after the discovery of the X-rays by Roentgen in 1895. Currently, the diagnostic and therapeutic applications of ionizing radiation (i.e., diagnostic radiology, interventional radiology, nuclear medicine, and radiotherapy) constitute an integral and important part of the everyday medical clinical practice. However, apart from their beneficial uses, ionizing radiations may also lead to harmful biological effects which are associated with their impact on the building block of biological tissues and organs, the cell. These effects may be either direct or indirect, deterministic or stochastic. Deterministic are the biological effects which appear for ionizing radiation doses above a threshold value and their severity is directly proportional to the dose received (e.g., erythema, cataract, etc.). On the contrary, the stochastic effects are associated with a likelihood of occurrence and there is no threshold dose for their appearance (e.g., cancer, heritable effects, etc.). The harmful effects of ionizing radiation do not concern only the patients who are irradiated during diagnosis or therapy but can also affect medical and paramedical staff participating in these procedures. Interventional radiologists and staff members are frequently exposed to doses of ionizing radiation and cataract is considered an issue of major concern.