Development of methodology for evaluation of 99mTc and 131I incorporated activities during lactation

Abstract

Internal contamination of babies may occur for milk ingestion or inhalation of mothers occupationallyexposed to ionizing radiation with possible incorporation or mothers submitted to medical exposuresduring lactation. Radionuclide concentrations in the mother´s milk may cause organ absorbed doses in thebabies proportionally to the breast volumes. Milk analysis allow to determine activities ingested by thebabies by determining the peak of mother´s milk considering the decrease of the activity rate and the milkactivities drunk at different time intervals. The work had the aim to develop simulators and methodologyto evaluate 99mTc and 131I in lactation, in the following steps: to prepare standard solution of contaminatedmilk separately with 99mTc and 131I; to build four breast simulators (600 g and 800 g) and respectivecalibration for two geometries (breast and whole-body) in the Whole-Body Counter Unit in Instituto deRadioproteção e Dosimetria. The results demonstrated the system efficiency to determine 99mTc and 131Iactivities in breasts during the lactation period. The methodology for positioning in the “breast geometry”seemed to be more efficient than the “whole-body geometry” for different breast volumes. The experimentallows achieving better evaluation of internal dosimetry of mothers and their young children.