just 20 mK. Dosimeters in radiotherapy (linear particle accelerator in external beam therapy) are routinely calibrated using ionization chambers or diode technology or gel dosimeters. Radiation-related quantities The following table shows radiation quantities in SI and non-SI units. Although the United States Nuclear Regulatory Commission permits the use of the units curie, rad, and rem alongside SI units, the European Union European units of measurement directives required that their use for "public health ... purposes" be phased out by 31 December 1985. Radiation exposure monitoring Records of legal dosimetry results are usually kept for a set period of time, depending upon the legal requirements of the nation in which they are used. Medical radiation exposure monitoring is the practice of collecting dose information from radiology equipment and using the data to help identify opportunities to reduce unnecessary dose in medical situations. See also Computational human phantom Health effects of radon Radiation dose reconstruction References External links Ionization chamber - "The confusing world of radiation dosimetry" - M.A. Boyd, U.S. Environmental Protection Agency. An account of chronological differences between USA and ICRP dosimetry systems. Tim Stephens and Keith Pantridge, 'Dosimetry, Personal Monitoring Film' (a short article on Dosimetry from the point of view of its relation to photography, in Philosophy of Photography, volume 2, number 2, 2011, pp. 153–158.) Radiobiology Radiation therapy Nuclear physics Medical physics Radiation protection