<unk> , also known as radiological<unk> , is defined by the International Atomic Energy Agency (IAEA) as "The<unk>  of people from harmful effects of exposure to ionizing<unk> , and the means for achieving this". Exposure can be from a source of<unk>  external to the human body or due to internal irradiation caused by the ingestion of radioactive contamination Ionizing<unk>  is widely used in industry and medicine, and can present a significant health hazard by causing microscopic damage to living tissue. There are two main categories of ionizing<unk>  health effects. At high exposures, it can cause "tissue" effects, also called "deterministic" effects due to the certainty of them happening, conventionally indicated by the unit gray and resulting in acute<unk>  syndrome. For low level exposures there can be statistically elevated risks of<unk> -induced cancer, called "stochastic effects" due to the uncertainty of them happening, conventionally indicated by the unit sievert. Fundamental to<unk>  is the avoidance or reduction of dose using the simple protective measures of time, distance and shielding. The duration of exposure should be limited to that necessary, the distance from the source of<unk>  should be maximised, and the source shielded wherever possible. To measure personal dose uptake in occupational or emergency exposure, for external<unk>  personal dosimeters are used, and for internal dose to due to ingestion of radioactive contamination, bioassay techniques are applied. For<unk>  and dosimetry assessment the International Commission on<unk>  (ICRP) and International Commission on<unk>  Units and Measurements (ICRU) publish recommendations and data which is used to calculate the biological effects on the human body of certain levels of<unk> , and thereby advise acceptable dose uptake limits.
Radiation protection
Automotive safety
Road traffic safety
Bicycle safety
Assistive technology
Lasers in cancer treatment
Drug development
Clinical engineering