Physics Bucharest 2017

Deterministic effects → Tissue reactions (ICRP 2007 – 2012)

• ICRP 60 – 1991 → Deterministic: casually determined by preceding events. • ICRP 103 - 2007 → They are not necessarly PREdetermined and can be modified after irradiation by the use of various biological response modifier. Stochastic are presumed to be unicellular in origin while Tissue /Organ reactions are due to injury in a population of cells. • ICRP 60 – 1991 → the emphasis was on radiation-induced cell killing in relation to tissue damage. • ICRP 118 - 2012 → 1) the cytotoxic effects of radiation cannot explain all tissue reactions (especially late effects - fibrosis); 2) non-lethal effects of radiation on cells and tissues, with the resultant disturbances in molecular cell signalling, also play a crucial role in determining tissue response to radiation; 3) more information has become available regarding the effect of biological response modifiers in mitigating tissue reactions, which has the effect of modifying threshold doses.