Radiation Dose to Patients in Diagnostic Nuclear Medicine

Abstract

In its 2007 Recommendations, ICRP introduced changes in the system of radiation protection that affect the calculation of effective dose and implied a revision of dose coefficients for internal exposure by administration of radiopharmaceuticals in medical diagnostics published in earlier publications, lastly in Publication 128. This report replaces the previous series of Publications on Radiation Dose to Patients from Radiopharmaceuticals (Publications 53, 80, 106 and 128) and the related Addenda published in Publications 62 (Erratum in Publication 75) as well as online. It provides data on individual radiopharmaceuticals and their labelled radioisotopes including their use in nuclear medicine; their physical half-lives; the biokinetic information available; the structure and parameter values of the proposed biokinetic model. Internal distribution and excretion of radiopharmaceuticals have been calculated using improved compartmental biokinetic models. These models are based on available experimental data and knowledge of human physiology also allowing more complex physiologically based model structures than in earlier reports, in an attempt to make them more realistic representations of uptake and retention in organs and tissues and of excretion. The Publication 100 Human Alimentary Tract Model (HATM) was also used when appropriate. For the calculation of the dose to the urinary bladder wall a dynamic bladder model has been used as well as a specific bladder voiding regime which is typical for the situation in the application of the radiopharmaceutical considered. The dose coefficients have been calculated implementing the changes that were introduced in Publication 103 to: the radiation weighting factors used in the calculation of equivalent doses to tissues; the tissue weighting factors used in the calculation of effective dose; and the calculation of effective dose based on averaging sex-specific tissue or organ equivalent doses. Dose calculations were also improved by using the updated radionuclide decay data of Publication 107 and specific absorbed fractions computed using the reference anatomical voxel phantoms of Publications 110 and 143 and published in Publications 133 and 155. This report gives sex-specific coefficients of absorbed dose to 27 target tissues or organs for patients in diagnostic nuclear medicine for the ages 3 months, 1 year, 5 years, 10 years, 15 years, and for adults. It also gives the corresponding effective dose coefficients for each age group considered. In cases when the group of patients considered deviates noticeably from the ICRP reference person, specific dose calculations were performed accordingly. Data are also given in an electronic Annex. The data presented here are intended for diagnostic applications of radiopharmaceuticals only. For therapeutic applications of radionuclides individual planning must be based on detailed patient-specific dosimetry.