Internal Bone Marrow Dosimetry: the Effect of the Exposure Due to 90sr Incorporated in yhe Adjacent Bone Segments

The paper is devoted to dosimetric modelling of the human red bone marrow (RBM) internal exposure due to beta-emitting 90Sr incorporated in spongiosa bone. The dose factor calculation (absorbed dose rate due to unit specific activity of 90Sr) is based on the modelling of radiation transport in segments of the skeleton bones with active hematopoiesis. Segmentation considerably simplifies the modelling, but can lead to an underestimation due to electron emission from the neighboring parts of the bone adjacent to the studied segment. The objective of the study is to determine this cross-fire effect on the absorbed dose in RBM. For this purpose, we analyze the results of the numerical experiment on modelling of dose absorption within the bone segments of various shape and size that were parts of the computational phantoms of skeletons of people of different sex and age. We analyze dose factor dependencies on the area of the spongiosa bone surface and the ratio of weights of bone and RBM. It is found that if the area of the spongiosa surface (SS) > 6 cm^2, then the effect of neighboring bone parts exposure is negligible. For a smaller SS the extension of the linear dimensions of the spongiosa bone by 2 mean electron path lengths results in dose factor increase proportional to the ratio of the extended spongiosa bone surface area to the original one to the power of 0,28. For human computational phantoms, these values are in the range 1,03 -- 1,21 and are used as adjustment coefficients for the dose factors. Relative standard uncertainty of the adjustment coefficient is 5%.

Keywords

numerical modelling; computational phantoms; 90Sr; red bone marrow; spongiosa bone

References

1. Loke K.S., Padhy A.K., Ng D.C., Goh A.S, Divgi C. Dosimetric Considerations in Radioimmunotherapy and Systemic Radionuclide Therapies: A Review. World Journal of Nuclear Medicine, 2011, vol. 10, no. 2, pp. 122-138. DOI: 10.4103/1450-1147.89780
2. Degteva M.O., Shagina N.B., Vorobyova M.I., Shishkina E.A., Tolstykh E.I., Akleev A.V. Contemporary Understanding of Radioactive Contamination of the Techa River in 1949-1956. Radiation Biology. Radioecology, 2016, vol. 56, no. 5, pp. 523-534. (in Russian)
3. Degteva M.O., Tolstykh E.I., Shishkina E.A., Shagina N.B., Volchkova A.Yu., Bougrov N.G., Napier B.A., Smith M.A., Anspaugh L.R. Enhancements in the Techa River Dosimetry System: TRDS-2016D Code for Reconstruction of Deterministic Estimates of Dose from Environmental Exposures. Health Physics, 2019, vol. 117, no. 4, pp. 378-387. DOI: 10.1097/HP.0000000000001067
4. Degteva M.O., Shishkina E.A., Tolstykh E.I., Zalyapin V.I., Sharagin P.A., Smith M.A., Napier B.A. Methodological Approach to Development of Dosimetric Models of the Human Skeleton for Beta-emitting Radionuclides. Radiation Hygiene, 2019, vol. 12, no. 2, pp. 66-75. DOI:10.21514/1998-426X-2019-12-2-66-75 (in Russian)
5. Degteva M.O., Tolstykh E.I., Shishkina E.A., Sharagin P.A., Zalyapin V.I., Volchkova A.Yu., Smith M.A., Napier B.A. Stochastic Parametric Skeletal Dosimetry Model for Humans: General Approach and Application to Active Marrow Exposure from Bone-Seeking Beta-Particle Emitters. PLos One, 2021, vol. 16, no. 10, article ID: e0257605, 32 p. DOI: 10.1371/journal.pone.0257605
6. Shishkina E.A., Zalyapin V.I., Timofeev Yu.S., Degteva M.O., Smith M.A., Napier B.A. Parametric Stochastic Model of Bone Structures to be Used in Computational Dosimetric Phantoms of Human Skeleton. Radiation and Applications, 2018, vol. 3, no. 2, pp. 133-137. DOI: 10.21175/RadJ.2018.02.022
7. Zalyapin V.I., Timofeev Yu.S., Shishkina E.A. Parametric Stochastic Model of Bone Geometry. Bulletin of the South Ural State University. Series: Mathematical Modelling, Programming and Computer Software, 2018, vol. 11, no. 2, pp. 44-57. DOI: 10.14529/mmp180204
8. Sharagin P.A., Shishkina E.A., Tolstykh E.I., Volchkova A.Yu., Smith M.A., Degteva M.O. Segmentation of Hematopoietic Sites of Human Skeleton for Calculations of Dose to Active Marrow Exposed to Bone-seeking Radionuclides. Medical Physics, 2018, vol. 3, pp. 154-158. DOI: 10.21175/RadProc.2018.33
9. Shishkina E.A., Sharagin P.A., Volchkova A.Yu. Analytical Description of the Dose Formation in Bone Marrow due to ^{90}Sr Incorporated in Calcified Tissues. Radiation Safety Issues, 2021, no. 3, pp. 72-82. (in Russian)
10. ICRP, 1995. Basic Anatomical and Physiological Data for Use in Radiological Protection - The Skeleton. ICRP Publication 70. Annals of the ICRP, 1995, vol. 25, no. 2, pp. 1-80.
11. Shishkina E.A., Timofeev Y.S., Volchkova A.Y., Sharagin P.A., Zalyapin V.I., Degteva M.O., Smith M.A., Napier B.A. Trabecula: A Random Generator of Computational Phantoms for Bone Marrow Dosimetry. Health Physics, 2020, vol. 118, no. 1, pp. 53-59. DOI: 10.1097/HP.0000000000001127
12. Sharagin P.A., Tolstykh E.I., Shishkina E.A., Napier B.A., Smith M.A., Degteva M.O. Dosimetric Modeling of Bone for Bone-Seeking Beta-Emitting Radionuclides: Size Parameters and Segmentation. Contemporary Issues of Radiobiology - 2021: International Scientific Conference Proceedings, Minsk, 2021, pp. 200-203. (in Russian)
13. Tolstykh E.I., Sharagin P.A., Shishkina E.A., Degteva M.O., Napier B.A., Smith M.A. Dosimetric Modeling of Red Bone Marrow Exposure from ^{89,90}Sr: Resolving Age-Dependent Trabecular Bone Parameters. Contemporary Issues of Radiobiology - 2021: International Scientific Conference Proceedings, Minsk, 2021, pp. 176-179. (in Russian)
14. Soppera N., Bossant M., Dupont E. JANIS 4: An Improved Version of the NEA Java-based Nuclear Data Information System. Nuclear Data Sheets, 2014, vol. 120, pp. 294-296. DOI: 10.1016/j.nds.2014.07.071