Research progress in the trace-level radionuclides <italic>in vivo</italic> counting experiment (TRACE)
Abstract
<p indent="0mm">The assessment of health risks from long-term and low-dose radiation exposure is one of the important scientific frontiers in the field of radiation protection. In contrast to the clear health effects of high doses, assessing health risk of low doses lacks the support of foundational experimental data. Based on the China Jinping Underground Laboratory, the TRACE group from Beijing Normal University is committed to providing essential scientific foundational experimental data for the assessment of potential risks of long-term and low-dose radiation through measurements of trace-level radionuclides in the human body. The first phase of TRACE group focuses on in vivo measurement of Pb-210 in the skull, with key issues including: (1) low signal-to-noise ratio; (2) significant efficiency calibration errors, and (3) the widespread sources of Pb-210 in the human body coupled with complex metabolic patterns. This paper introduces the main research progress made by the TRACE group on the key issues mentioned above. To address issue (1), the TRACE group conducted background source analysis in the shielding room of in vivo measurement. The results showed that cosmic rays, background from shielding materials and measuring instruments, and K-40 in the subject’s body are the main contributors, accounting for approximately 12%, 24%, and 58%, respectively. To address issue (2), the TRACE group studied the impact of different phantom types on efficiency calibration of Pb-210 in the skull. The results indicated that counting efficiency deviations between the lower-fidelity BOMAB and MIRD phantoms and the higher-fidelity MIDA phantom can exceed 40%. To address issue (3), the TRACE group developed a whole-body Pb-210 biokinetic model and performed Pb-210 source tracing. The results showed that the specific activity range of Pb-210 in typical intake sources, such as tea and tobacco, is <sc>8.15–49.67 Bq/kg</sc> and <sc>21.74–31.16 Bq/kg,</sc> respectively. </p>
