The Röntgen equivalent physical or rep (symbol rep) is a legacy unit of absorbed dose first introduced by Herbert Parker in 1945 to replace an improper application of the roentgen unit to biological tissue.[1] It is the absorbed energetic dose before the biological efficiency of the radiation is factored in. The rep has variously been defined as 83 or 93 ergs per gram of tissue (8.3/9.3 mGy)[2] or per cm3 of tissue.[3]
At the time, this was thought to be the amount of energy deposited by 1 roentgen.[4] Improved measurements have since found that one roentgen of air kerma deposits 8.77 mGy in dry air, or 9.6 mGy in soft tissue, but the rep was defined as a fixed number of ergs per unit gram.[5]
A 1952 handbook from the US National Bureau of Standards affirms that "The numerical coefficient of the rep has been deliberately changed to 93, instead of the earlier 83, to agree with L. H. Gray's 'energy-unit'."[6] Gray's 'energy unit' was " one roentgen of hard gamma resulted in about 93 ergs per gram energy absorption in water". The lower range value of 83.8 ergs was the value in air corresponding to wet tissue.[7] The rep was commonly used until the 1960s,[8] but was gradually displaced by the rad starting in 1954 and later the gray starting in 1977.
Referencesedit
^Cantrill, S.T; H.M. Parker (5 January 1945). . Argonne National Laboratory: US Atomic Energy Commission. Archived from the original on 30 November 2012. Retrieved 14 May 2012. {{cite journal}}: Cite journal requires |journal= (help)
^Dunning, John R.; et al. (1957). A Glossary of Terms in Nuclear Science and Technology. American Society of Mechanical Engineers.
^Bertram, V. A. Low-Beer (1950). The clinical use of radioactive isotopes. Thomas.
^Anderson, Elda E. (March 1952). "Units of Radiation and Radioactivity". Public Health Reports. 67 (3): 293–297. doi:10.2307/4588064. JSTOR 4588064. PMC2030726. PMID 14900367.
^"APPENDIX E: Roentgens, RADs, REMs, and other Units". Princeton University Radiation Safety Guide. Princeton University. Retrieved 10 May 2012.
^National Bureau of Standards (1952). Radiological Monitoring Methods and Instruments(PDF). Vol. 51. US Department of Commerce. Retrieved 16 November 2012.
^US patent 3568311, Elliott J. Lawton, "INSULATING AND SPACING ELECTRICALLY CONDUCTIVE MEMBERS", published 1971-03-09, issued 1971-03-01, assigned to General Electric Company
röntgen, equivalent, physical, symbol, legacy, unit, absorbed, dose, first, introduced, herbert, parker, 1945, replace, improper, application, roentgen, unit, biological, tissue, absorbed, energetic, dose, before, biological, efficiency, radiation, factored, v. The Rontgen equivalent physical or rep symbol rep is a legacy unit of absorbed dose first introduced by Herbert Parker in 1945 to replace an improper application of the roentgen unit to biological tissue 1 It is the absorbed energetic dose before the biological efficiency of the radiation is factored in The rep has variously been defined as 83 or 93 ergs per gram of tissue 8 3 9 3 mGy 2 or per cm3 of tissue 3 At the time this was thought to be the amount of energy deposited by 1 roentgen 4 Improved measurements have since found that one roentgen of air kerma deposits 8 77 mGy in dry air or 9 6 mGy in soft tissue but the rep was defined as a fixed number of ergs per unit gram 5 A 1952 handbook from the US National Bureau of Standards affirms that The numerical coefficient of the rep has been deliberately changed to 93 instead of the earlier 83 to agree with L H Gray s energy unit 6 Gray s energy unit was one roentgen of hard gamma resulted in about 93 ergs per gram energy absorption in water The lower range value of 83 8 ergs was the value in air corresponding to wet tissue 7 The rep was commonly used until the 1960s 8 but was gradually displaced by the rad starting in 1954 and later the gray starting in 1977 References edit Cantrill S T H M Parker 5 January 1945 The Tolerance Dose Argonne National Laboratory US Atomic Energy Commission Archived from the original on 30 November 2012 Retrieved 14 May 2012 a href Template Cite journal html title Template Cite journal cite journal a Cite journal requires journal help Dunning John R et al 1957 A Glossary of Terms in Nuclear Science and Technology American Society of Mechanical Engineers Bertram V A Low Beer 1950 The clinical use of radioactive isotopes Thomas Anderson Elda E March 1952 Units of Radiation and Radioactivity Public Health Reports 67 3 293 297 doi 10 2307 4588064 JSTOR 4588064 PMC 2030726 PMID 14900367 APPENDIX E Roentgens RADs REMs and other Units Princeton University Radiation Safety Guide Princeton University Retrieved 10 May 2012 National Bureau of Standards 1952 Radiological Monitoring Methods and Instruments PDF Vol 51 US Department of Commerce Retrieved 16 November 2012 Meggitt G Taming the Rays pub Lulu com 2008 US patent 3568311 Elliott J Lawton INSULATING AND SPACING ELECTRICALLY CONDUCTIVE MEMBERS published 1971 03 09 issued 1971 03 01 assigned to General Electric Company See also editRadiation poisoning Rontgen equivalent man rem nbsp This radioactivity related article is a stub You can help Wikipedia by expanding it vte nbsp This standards or measurement related article is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title Rontgen equivalent physical amp oldid 1166016095, wikipedia, wiki, book, books, library,
