INDIVIDUAL THYROID DOSE ESTIMATES FOR THE GENOMIC STUDY OF FOLLICULAR CARCINOMAS AND ADENOMAS IN PARTICIPANTS OF THE...

Assessment of thyroid doses among participants of the Chornobyl Tissue Bank (CTB) enrolled in the study of the genomic landscape of thyroid follicular carcinomas and follicular adenomas, using updated methodologies and data on residential history and dietary patterns collected during the study through personal dosimetry interviews.

This study presents an assessment of thyroid doses in 140 participants of the Chornobyl Tissue Bank (CTB) with pathologically confirmed diagnoses of follicular adenoma and follicular thyroid carcinoma.Thyroid doses from 131I intake were estimated using the substantially revised 'Thyroid Dosimetry System 2020 for Ukraine' (TDU20). In addition, the data on residential and dietary history have been obtained through personal interviews with 85 individuals for whom dosimetryrelated data were limited. Radiation doses to the thyroid were also estimated for the following minor exposure pathways: (a) intake of short lived radionuclides (132Te+132I and 133I) via inhalation and ingestion; (b) external irradiation from radionuclides deposited on the ground; and (c) ingestion of 134Cs and 137Cs with contaminated foodstuffs.

The arithmetic mean of thyroid doses estimated in this study from all exposure pathways combined was 445 mGy, while the median dose was 71 mGy. Among study participants, a broad range of thyroid doses was observed, from 0.23 mGy to 14 Gy. The major exposure pathway was 131I intake, which accounted for a median contribution of 92 % to the thyroid dose. Among individuals who were interviewed in the study, thyroid doses from 131I intake that were calculated using TDU20 and individual questionnaire data were lower than doses that did not include the interview data: 105 mGy vs. 150 mGy for the arithmetic mean and 46 mGy vs. 98 mGy for the median, respectively.Uncertainties in dose estimates from 131I intake were characterized using the geometric standard deviation of 1,000 individual stochastic dose realizations. As a result, the geometric standard deviation ranged from 1.3 to 6.1, with an overall arithmetic mean of 3.1 and a median of 3.3 across all study participants.

This study demonstrated that the use of individual questionnaire data in dose assessment for participants who completed personal dosimetric interviews had an impact on the estimated thyroid doses. In conducting specialized studies aimed at identifying potential associations between thyroid dose and key demographic, clinical, pathological, and moleculargenetic indicators, it is valuable to carry out personal dosimetric interviews to obtain detailed residential and dietary histories of study participants. Incorporating such information allows for more realistic individual dose estimates.