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The committed dose in radiological protection is a measure of the stochastic health risk due to an intake of radioactive material into the human body. Stochastic in this context is defined as the ''probability'' of cancer induction and genetic damage, due to low levels of radiation. The SI unit of measure is the sievert. A committed dose from an internal source represents the same effective risk as the same amount of effective dose applied uniformly to the whole body from an external source, or the same amount of equivalent dose applied to part of the body. The committed dose is not intended as a measure for deterministic effects such as radiation sickness which is defined as the ''severity'' of a health effect which is certain to happen. The radiation risk proposed by the International Commission on Radiological Protection (ICRP) predicts that an effective dose of one sievert carries a 5.5% chance of developing cancer. Such a risk is the sum of both internal and external radiation dose.〔ICRP publication 103 - Paragraph 83.〕 ==ICRP Definition== The ICRP states "Radionuclides incorporated in the human body irradiate the tissues over time periods determined by their physical half-life and their biological retention within the body. Thus they may give rise to doses to body tissues for many months or years after the intake. The need to regulate exposures to radionuclides and the accumulation of radiation dose over extended periods of time has led to the definition of committed dose quantities".〔ICRP Publication 103 paragraph 140〕 The ICRP defines two dose quantities for individual committed dose. Committed equivalent dose, H T(''t'') is the time integral of the equivalent dose rate in a particular tissue or organ that will be received by an individual following intake of radioactive material into the body by a Reference Person, where t is the integration time in years.〔ICRP publication 103 - Glossary.〕 This refers specifically to the dose in a specific tissue or organ, in the similar way to external equivalent dose. Committed effective dose, E(''t'') is the sum of the products of the committed organ or tissue equivalent doses and the appropriate tissue weighting factors ''W''T, where ''t'' is the integration time in years following the intake. The commitment period is taken to be 50 years for adults, and to age 70 years for children.〔 This refers specifically to the dose to the whole body, in the similar way to external effective dose. The committed effective dose is used to demonstrate compliance with dose limits and is entered into the "dose of record" for occupational exposures used for recording, reporting and retrospective demonstration of compliance with regulatory dose limits.〔ICRP publication 103 - paragraph B225 and glossary.〕 The ICRP further states "For internal exposure, committed effective doses are generally determined from an assessment of the intakes of radionuclides from bioassay measurements or other quantities (e.g., activity retained in the body or in daily excreta). The radiation dose is determined from the intake using recommended dose coefficients".〔ICRP publication 103 - Paragraph 144.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「committed dose」の詳細全文を読む スポンサード リンク
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