[Biological mechanisms of radiation effects].
BACKGROUND
Exposure to ionizing radiation for diagnostic purposes is inevitable in modern medicine. The therapeutic application of irradiation is highly effective against cancer; however, this implies exposure of normal tissue structures to significant doses of radiation. Diagnostic or therapeutic exposure to ionizing radiation can result in tissue changes and tumor induction in the long term. Knowledge of the biological mechanisms underlying these effects is essential for individualization of the application.


OBJECTIVE
This article examines the biological mechanisms at the tissue and molecular level, the clinical manifestation of radiation effects, dose-dependence of the risk and the temporal progression as well as influencing factors.


CONCLUSIONS
The time course of the reaction of tissues to radiation exposure extends over wide ranges up to many decades. The effects of radiation on tissues are classified into early and late and their pathobiology is significantly different. Various factors (R) influencing the clinical manifestation of radiation effects have been identified related to the exposure pattern. The radiation tolerance of normal tissue structures regarding the induction of functional deficits shows great variation but always has a threshold value, which is usually not exceeded in diagnostic procedures. The risk of a radiation-induced fatal malignancy (total body exposure 5%/Gy) for a medical administration of radiation must be considered as very low in comparison to the natural risks. Informed consent of patients must reflect this in a balanced way.
ATRAB - Angewandte und Translationale Radiobiologie, Univ.-Klinik für Strahlentherapie, Medizinische Universität Wien, Währinger Gürtel 18-20, 1090, Wien, Österreich.
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Gruber
ATRAB - Angewandte und Translationale Radiobiologie, Univ.-Klinik für Strahlentherapie, Medizinische Universität Wien, Währinger Gürtel 18-20, 1090, Wien, Österreich. Wolfgang.doerr@meduniwien.ac.at.
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Dörr
D004307:Dose-Response Relationship, Radiation; D006801:Humans; D009381:Neoplasms, Radiation-Induced / Q000209:etiology; D058958:Organs at Risk / Q000528:radiation effects*; D011829:Radiation Dosage; D000069079:Radiation Exposure; D011832:Radiation Injuries; D013997:Time Factors
Dose-effect relationship; Pathobiology; Radiation risk; Radiation sensitivity; Tissue effects