Parametric Stochastic Model of Bone Structures to Be Used in Computational Dosimetric Phantoms of Human Skeleton

Shishkina, E.A.; Zalyapin, V.I.; Timofeev, Yu. S.; Smith, Michael A.; Napier, Bruce A.

doi:10.21175/radj.2018.02.022

Cited by 11 publications

(13 citation statements)

References 13 publications

(14 reference statements)

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“…Dose factors were calculated for each from 67 segments with the use of Monte -Carlo simulation of electron-photon transport [9]. The obtained values were averaged within the hematopoietic site, taking into account segment-specific bone marrow mass.…”

Section: Results Of Dose Factors Calculationmentioning

confidence: 99%

Segmentation of Hematopoietic Sites of Human Skeleton for Calculations of Dose to Active Marrow Exposed to Bone-Seeking Radionuclides

Sharagin¹,

Shishkina²,

Толстых³

et al. 2019

RAD Conference Proceedings

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The Techa River (the Urals, Russia) was heavily contaminated due to the release of radionuclides from the Mayak Production Association. The radioactive releases included bone-seeking beta-emitters such as 90 Sr and 89 Sr that contribute to doses to bone marrow. Moreover, 90 Sr is a long-lived isotope, the uptake of which leads to a chronic bone marrow exposure known to result in an increased risk of leukemias. Ongoing epidemiological studies of the long-term effects of chronic radiation exposure are being performed for the Techa River Cohort members. Radiation dosimetry is a part of this study, of which, the internal dose estimates for active bone marrow exposed to beta emission of Sr isotopes incorporated in calcified tissue is an important component. Internal dose calculations, which are based on electron-photon transport simulations, require geometrical descriptions of bone shapes and bone microstructures of the main hematopoietic sites of the human skeleton (ribs, vertebrae, pelvic bones, femur, humeri, bones of the skull, sternum, clavicle and scapula). For this purpose, the parametric approach for modeling bone geometry was elaborated. The proposed approach can be used to segment and define each of the bone sites as simple geometric shapes for which parameters can be derived. The aim of the paper is to present the principles of bone segmentation. Dose factors that convert the activity concentration of bone-seeking radionuclides into a corresponding bone marrow dose rate were calculated for each segment. The calculations were done with MCNP6. The bone segmentation allows optimizing the size of the computational phantom (in terms of voxel number), substituting the complex-shaped bone model with a set of simple stylized phantoms and taking into account the heterogeneity of bone microstructure.

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Section: Results Of Dose Factors Calculationmentioning

confidence: 99%

Segmentation of Hematopoietic Sites of Human Skeleton for Calculations of Dose to Active Marrow Exposed to Bone-Seeking Radionuclides

Sharagin¹,

Shishkina²,

Толстых³

et al. 2019

RAD Conference Proceedings

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“…A general approach to bone dosimetric modeling for 89 Sr and 90 Sr+ 90 Y was described in [ 61 ]. The hematopoietic sites are modeled by dividing them into small segments described by simple geometric shapes [ 20 , 21 ]. The cortical layer with a thickness of Ct .…”

Section: General Approach and Modeling Tasks To Be Solvedmentioning

confidence: 99%

“…Sp ; BV/TV) . Stochastic modeling of radiation transport in a heterogeneous medium simulating the distribution of bone tissue and marrow in each of the segments is performed by Monte Carlo methods [ 20 ].…”

Section: General Approach and Modeling Tasks To Be Solvedmentioning

confidence: 99%

“…Some segmentation information is readily available in our previous publications. For example, segmentation of the vertebra and ribs of adult males were described in [ 20 , 62 ].…”

Section: General Approach and Modeling Tasks To Be Solvedmentioning

confidence: 99%

“…The current paper presents a general description of the voxel-based Stochastic Parametric Skeletal Dosimetry (SPSD) model for humans, originally proposed by E. Shishkina and V. Zalyapin [ 20 , 21 ]. This SPSD model accounts for the individual variability of the macro- and microstructure of bone tissues and is currently implemented for males and females of different ages beginning from birth.…”

Section: Introductionmentioning

confidence: 99%

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Stochastic parametric skeletal dosimetry model for humans: General approach and application to active marrow exposure from bone-seeking beta-particle emitters

et al. 2021

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The objective of this study is to develop a skeleton model for assessing active marrow dose from bone-seeking beta-emitting radionuclides. This article explains the modeling methodology which accounts for individual variability of the macro- and microstructure of bone tissue. Bone sites with active hematopoiesis are assessed by dividing them into small segments described by simple geometric shapes. Spongiosa, which fills the segments, is modeled as an isotropic three-dimensional grid (framework) of rod-like trabeculae that “run through” the bone marrow. Randomized multiple framework deformations are simulated by changing the positions of the grid nodes and the thickness of the rods. Model grid parameters are selected in accordance with the parameters of spongiosa microstructures taken from the published papers. Stochastic modeling of radiation transport in heterogeneous media simulating the distribution of bone tissue and marrow in each of the segments is performed by Monte Carlo methods. Model output for the human femur at different ages is provided as an example. The uncertainty of dosimetric characteristics associated with individual variability of bone structure was evaluated. An advantage of this methodology for the calculation of doses absorbed in the marrow from bone-seeking radionuclides is that it does not require additional studies of autopsy material. The biokinetic model results will be used in the future to calculate individual doses to members of a cohort exposed to 89,90Sr from liquid radioactive waste discharged to the Techa River by the Mayak Production Association in 1949–1956. Further study of these unique cohorts provides an opportunity to gain more in-depth knowledge about the effects of chronic radiation on the hematopoietic system. In addition, the proposed model can be used to assess the doses to active marrow under any other scenarios of 90Sr and 89Sr intake to humans.

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Bone marrow dosimetry for mice: exposure from bone-seeking 89,90Sr

Shishkina

Shuiskaya

Sharagin

2022

Radiat Environ Biophys

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Studies of radiobiological effects in murine rodents exposed to internal radiation in the wild or in laboratory experiments require a dosimetric support. The main problem of bone marrow (BM) dosimetry for boneseeking β-emitters is dosimetric modeling due to the fact that the bone is a heterogeneous structure with complex microarchitecture. To date, there are several approaches to calculating the absorbed dose in BM, which mostly use rough geometric approximations. Recently, in the framework of studies of people exposed to 90 Sr in the Urals, a new approach (SPSD) has been developed. The aim of current study was to pilot test the possibility of extension of the SPSD-approach elaborated for humans to mice. The computational phantoms of femur bones of laboratory animals (C57BL/6, C57BL/6J, BALB/c, BALB/cJ) aged 5-8 weeks (growing) and >8 weeks (adults) were created. The dose factors to convert the 89,90 Sr activity concentrations in a bone tissue into units of the dose rate absorbed in the bone marrow were estimated as follows: DFSr-90(BMTBV+CBV) is equal to 1.75±0.42 and 2.57±0.93 (μGy day -1 ) per (Bq g -1 ) for growing and adults, respectively; DFSr-89(BMTBV+CBV) is equal to 1.08±0.27 and 1.66±0.67 (μGy day -1 ) per (Bq g -1 ) for growing and adults, respectively. These results are about 2.5 times lower than skeleton-average DF, calculated assuming the homogenous bone, where source and target coincide. The study demonstrates the possibility of application of the SPSD-approach elaborated for humans to non-human mammals.

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Parametric Stochastic Model of Bone Structures to Be Used in Computational Dosimetric Phantoms of Human Skeleton

Cited by 11 publications

References 13 publications

Segmentation of Hematopoietic Sites of Human Skeleton for Calculations of Dose to Active Marrow Exposed to Bone-Seeking Radionuclides

Segmentation of Hematopoietic Sites of Human Skeleton for Calculations of Dose to Active Marrow Exposed to Bone-Seeking Radionuclides

Stochastic parametric skeletal dosimetry model for humans: General approach and application to active marrow exposure from bone-seeking beta-particle emitters

Bone marrow dosimetry for mice: exposure from bone-seeking 89,90Sr

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