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Role of the weighting tissue factors in dose assessments
Yu. V. Bonchuk
State Institution “National Research Center for Radiation Medicine of the National Academy of MedicalSciences of Ukraine”, Melnykov str., 53, Kyiv, 04050, Ukraine
Objective. To determine the influence of system of tissue weighting factors wT, established by the International Commission on Radiological Protection, on the dose assessment in human.
Material and methods. The effective dose is defined as a sum of equivalent doses in specified organs and tissues, each multiplied by the appropriate wT value. Application of different wT systems to a specific set of equivalent doses produces different assessments of effective doses. Comparison of the effective doses values provides an opinion about the wT system influence on dose assessment.
Results. The role of wT systems, established in ICRP Publications 26, 60 and 103, on the assessment of external and internal exposure to humans is reviewed. It has been demonstrated that the transition of wT system from ICRP Publications 26 to ICRP Publication 60 has resulted in a significantly greater changes in the assessment of effective doses of external exposure (up to 30 times) than the corresponding transition from ICRP Publication 60 to ICRP Publication 103.
Conclusion. Application of wT system from ICRP Publication 103 compared with ICRP Publication 60 does not change the assessment of effective doses for more than 20 % for all radionuclides in the assessment of external doses and for the large majority of radionuclides (97 %) in the assessment of internal doses due to ingestion. For most iodine of the internal dose assessment will decrease (up to 20 %). Assessments of effective internal doses due to inhalation will decrease for 67 % of radionuclides. Cancellation of the “splitting rule” (introduced by ICRP Publication 60) and decrease wT value for the thyroid from 0.05 to 0.04 are the primary reasons of the decrease.
Key words: tissue weighting factors, exposure doses.
Problems of radiation medicine and radiobiology. 2013;18:38–49.
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