radiobiologie

Radiobiology is the study of the effects of ionizing radiation on living systems, from molecules to populations. It investigates how radiation interacts with biological material, induces DNA damage, and triggers cellular and tissue responses that influence health, disease, and heredity. The field underpins medical applications and radioprotection.

Ionizing radiation includes photons (X-rays and gamma rays) and particles (alpha, beta, neutrons). Doses are measured in grays (Gy) for absorbed energy and sieverts (Sv) for biological impact. Linear energy transfer (LET) differentiates high- and low-LET radiations, affecting damage patterns and repair needs. Dose rate and fractionation influence tissue responses, with higher dose rates generally causing more acute effects.

Radiation damages DNA, causing single- and double-strand breaks and complex lesions. Cells respond with signaling, cell-cycle arrest, and repair pathways such as non-homologous end joining and homologous recombination. Irreparable damage can lead to apoptosis or senescence; surviving cells may accumulate mutations, potentially contributing to cancer or heritable effects.

Biological effects include deterministic effects with thresholds (skin injury, radiation sickness) and stochastic effects (cancer, heritable changes) without a fixed threshold. Risk assessments often use the linear no-threshold model, though alternatives exist. Dose, dose rate, tissue sensitivity, and age modulate risk.

Applications include radiotherapy, diagnostic imaging, and nuclear medicine. Radioprotection aims for ALARA (as low as reasonably achievable) through shielding, time management, and distancing, guided by international guidance from organizations such as ICRP and IAEA. Monitoring and regulation ensure safe occupational and public exposure.

Key milestones span early X-ray discoveries, Muller’s mutagenesis work, and the development of models that inform therapy and safety.