Journal of Radiation Protection and Research

The Korean Association for Radiation Protection (대한방사선방어학회)
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Investigation on Individual Variation of Organ Doses for Photon External Exposures: A Monte Carlo Simulation Study

  • Yumi Lee (Department of Radiation Convergence Engineering, Yonsei University) ;
  • Ji Won Choi (Department of Radiation Convergence Engineering, Yonsei University) ;
  • Lior Braunstein (Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center) ;
  • Choonsik Lee (Division of Cancer Epidemiology and Genetics, National Cancer Institute) ;
  • Yeon Soo Yeom (Department of Radiation Convergence Engineering, Yonsei University)
  • Received : 2023.11.01
  • Accepted : 2024.02.06
  • Published : 2024.03.31
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Abstract

Background: The reference dose coefficients (DCs) of the International Commission on Radiological Protection (ICRP) have been widely used to estimate organ doses of individuals for risk assessments. This approach has been well accepted because individual anatomy data are usually unavailable, although dosimetric uncertainty exists due to the anatomical difference between the reference phantoms and the individuals. We attempted to quantify the individual variation of organ doses for photon external exposures by calculating and comparing organ DCs for 30 individuals against the ICRP reference DCs. Materials and Methods: We acquired computed tomography images from 30 patients in which eight organs (brain, breasts, liver, lungs, skeleton, skin, stomach, and urinary bladder) were segmented using the ImageJ software to create voxel phantoms. The phantoms were implemented into the Monte Carlo N-Particle 6 (MCNP6) code and then irradiated by broad parallel photon beams (10 keV to 10 MeV) at four directions (antero-posterior, postero-anterior, left-lateral, right-lateral) to calculate organ DCs. Results and Discussion: There was significant variation in organ doses due to the difference in anatomy among the individuals, especially in the kilovoltage region (e.g., <100 keV). For example, the red bone marrow doses at 0.01 MeV varied from 3 to 7 orders of the magnitude depending on the irradiation geometry. In contrast, in the megavoltage region (1-10 MeV), the individual variation of the organ doses was found to be negligibly small (differences <10%). It was also interesting to observe that the organ doses of the ICRP reference phantoms showed good agreement with the mean values of the organ doses among the patients in many cases. Conclusion: The results of this study would be informative to improve insights in individual-specific dosimetry. It should be extended to further studies in terms of many different aspects (e.g., other particles such as neutrons, other exposures such as internal exposures, and a larger number of individuals/patients) in the future.

Keywords

Acknowledgement

This work was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea (No. 20214000000070), the National Research Foundation of Korea (NRF) grant funded by the Korean government (No. 2022R1C1C100809312), "Regional Innovation Strategy (RIS)" through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (MOE) (2022RIS-005).

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