Ionising radiation is widely used in biomedical research. Such research is normally carried out in the laboratory and using different animal models. Research on normal tissue radiobiology aims at the investigation of the pathophysiological mechanisms and the consequences of ionising radiation. Pre-clinical in vivo studies in experimental animals largely focus on the characterisation of the pathophysiology of normal tissue reactions, the identification of potential biomarkers or the establishment of assays for predicting normal tissue toxicity of radiotherapy. Establishment of tumor xenograft models, involving implantation of human patient-derived tumors into immunodeficient animals, is a valuable research tool to investigate the biological effects of ionizing radiation on the disease mechanism of cancer.
Studies involving radiation exposure of patients adds another level of risk that must be evaluated by an institutional ethics review board with assistance of a radiation expert or radiation safety committee. In all investigations involving exposure of humans, a careful estimation of the radiation dose to the patients or volunteers should be made. The associated risks should then be weighted against the benefits for the patients or the society when volunteers are involved. A reasonable alternative is the ex-vivo exposure of tumor specimen, human blood or skin samples obtained from patients or healthy volunteers, to avoid the hazard of radiation exposure. Approval by an institutional ethics review board or human studies committee must be obtained prior to conducting human subject research. The researchers' role is to conduct their research ethically while maximizing benefits to the society and minimizing harm to the participants. ICRP has provided recommendations in the guidance ICRP Publication 105 Radiological Protection in Medicine and a previous ICRP Publication 62 Radiological Protection in Biomedical Research.