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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Opportunistic bone density screening for the abdominal radiologist using colored CT images: a pilot retrospective study

Purpose: The purpose of the study was to develop an accurate and reproducible method for detecting low spinal bone density on abdominal CT images. Methods: For this IRB-approved HIPAA-compliant single-center retrospective study, nonenhanced CT images of the lower abdomen were obtained in 631 African-American participants. Mean attenuation of L3/L4 was associated with quantitative CT bone density (QCT) in a randomly selected training cohort (N = 511), and receiver operating characteristics analysis was used to identify the optimal mean attenuation threshold for differentiating normal from low bone density. Custom image processing software was used to generate grayscale and colored CT images of the midline spine, with green for normal and red for low bone density. Five radiologists independently assessed bone density at L3/L4 in a validation cohort (N = 120) using various methods: QCT, visual assessment of sagittal grayscale images (Grayscale), quantitative measurement of mean attenuation on a midline sagittal image (Attenuation), and visual assessment of a midline sagittal colored image (Color). Accuracy was calculated using the average QCT bone density as a reference standard. Inter-observer agreement was assessed using intraclass correlation coefficient (ICC). Results: The optimal mean attenuation threshold for differentiating normal from low bone density at L3/L4 was 145 Hounsfield Units. The average accuracy of Grayscale, Attenuation, and Color methods was 58, 87, and 91% (p < 0.001), respectively. Inter-observer agreement was poor for Grayscale (ICC: 0.20; 95% CI 0.12, 0.28) and excellent for both Attenuation (ICC: 0.85; 95% CI 0.73, 0.91) and Color methods (ICC: 0.87; 95% CI 0.83, 0.90). Conclusion: Detection of low spinal bone density using colored abdominal CT images was highly accurate and reproducible.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Persistent organic pollutants, skull size and bone density of polar bears (Ursus maritimus) from East Greenland 1892–2015 and Svalbard 1964–2004

Highlights: • Density in East Greenland males decreased over time. • Size in East Greenland females tented to decrease over time. • Size was highest in Svalbard polar bears. • Density was positive correlated to POPs. • Environmental changes and POPs may affect bone density and size. We investigated skull size (condylobasal length; CBL) and bone mineral density (BMD) in polar bears (Ursus maritimus) from East Greenland (n = 307) and Svalbard (n = 173) sampled during the period 1892–2015 in East Greenland and 1964–2004 at Svalbard. Adult males from East Greenland showed a continuous decrease in BMD from 1892 to 2015 (linear regression: p < 0.01) indicating that adult male skulls collected in the early pre-pollution period had the highest BMD. A similar decrease in BMD over time was not found for the East Greenland adult females. However, there was a non-significant trend that the skull size of adult East Greenland females was negatively correlated with collection year 1892–2015 (linear regression: p = 0.06). No temporal change was found for BMD or skull size in Svalbard polar bears (ANOVA: all p > 0.05) nor was there any significant difference in BMD between Svalbard and East Greenland subpopulations. Skull size was larger in polar bears from Svalbard than from East Greenland (two-way ANOVA: p = 0.003). T-scores reflecting risk of osteoporosis showed that adult males from both East Greenland and Svalbard are at risk of developing osteopenia. Finally, when correcting for age and sex, BMD in East Greenland polar bears increased with increasing concentrations of persistent organic pollutants (POPs) i.e. ΣPCB (polychlorinated biphenyls), ΣHCH (hexachlorohexane), HCB (hexachlorobenzene) and ΣPBDE (polybrominated diphenyl ethers) while skull size increased with ΣHCH concentrations all in the period 1999–2014 (multiple linear regression: all p < 0.05, n = 175). The results suggest that environmental changes over time, including exposure to POPs, may affect bone density and size of polar bears.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Perfluoroalkyl substances, bone density, and cardio-metabolic risk factors in obese 8–12 year old children: A pilot study

Highlights: • Cross sectional study of 48 obese children aged 8–12 years. • Serum Perfluoroalkyl substances (PFASs), measured by UPLC-ESI-MS/MS. • In 23 children, bone health assessed using calcaneal quantitative ultrasound. • PFNA showed significant negative relationship with bone health. • PFNA associated with raised systolic blood pressure and lipids. Perfluoroalkyl substances (PFASs), including perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorohexane sulfonic acid (PFHxS), and perfluorononanoic acid (PFNA), have been associated with adverse bone, and metabolic changes in adults. However association of PFASs with bone health in children is understudied. Considering their role as endocrine disruptors, we examined relationships of four PFASs with bone health in children.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Loss of PiT-2 results in abnormal bone development and decreased bone mineral density and length in mice

Highlights: • PiT-2 deficiency decreased mineral density in craniofacial and long bones in mice. • Bone length was reduced in long bones in PiT-2 deficient mice. • Trabecular and cortical bone mineral density were decreased in PiT-2 deficient mice. • Static bone morphometric parameters were altered in PiT-2 deficient mice. • PiT-2 deficiency altered craniofacial bone morphology. Normal bone mineralization requires phosphate oversaturation in bone matrix vesicles, as well as normal regulation of phosphate metabolism via the interplay among bone, intestine, and kidney. In turn, derangement of phosphate metabolism greatly affects bone function and structure. The type III sodium-dependent phosphate transporters, PiT-1 and PiT-2, are believed to be important in tissue phosphate metabolism and physiological bone formation, but their requirement and molecular roles in bone remain poorly investigated. In order to decipher the role of PiT-2 in bone, we examined normal bone development, growth, and mineralization in global PiT-2 homozygous knockout mice. PiT-2 deficiency resulted in reduced vertebral column, femur, and tibia length as well as mandibular dimensions. Micro-computed tomography analysis revealed that bone mineral density in the mandible, femur, and tibia were decreased, indicating that maintenance of bone function and structure is impaired in both craniofacial and long bones of PiT-2 deficient mice. Both cortical and trabecular thickness and mineral density were reduced in PiT-2 homozygous knockout mice compared with wild-type mice. These results suggest that PiT-2 is involved in normal bone development and growth and plays roles in cortical and trabecular bone metabolism feasibly by regulating local phosphate transport and mineralization processes in the bone. Further studies that evaluate bone cell-specific loss of PiT-2 are now warranted and may yield insight into complex mechanisms of bone development and growth, leading to identification of new therapeutic options for patients with bone diseases.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Quantitative impact of changes in marrow cellularity, skeletal size, and bone mineral density on active marrow dosimetry based upon a reference model

Purpose The hematopoietically active tissues of skeletal bone marrow are a prime target for computational dosimetry given potential risks of leukemia and, at higher dose levels, acute marrow toxicity. The complex three‐dimensional geometry of trabecular spongiosa, however, complicates schema for dose assessment in such a way that only a few reference skeletal models have been developed to date, and which are based upon microimaging of a limited number of cadaveric bone spongiosa cores. The question then arises as to what degree of accuracy is achievable from reference skeletal dose models when applied to individual patients or specific exposed populations? Methods Patient variability in marrow dosimetry were quantified for three skeletal sites — the ribs, lumbar vertebrae, and cranium — for the beta‐emitters 45 Ca, 153 Sm, and 90 Y, and the alpha‐particle emitters 223 Ra, 219 Rn, and 215 Po, the latter two being the immediate progeny of the former. For each radionuclide and bone site, three patient parameters were altered from their values in the reference model: (1) bone size as a surrogate for patient stature, (2) marrow cellularity as a surrogate for age‐ or disease‐related changes in marrow adiposity, and (3) the trabecular bone volume fraction as a surrogate for bone mineral density. Marrow dose variability is expressed as percent differences in the radionuclide S value given by the reference model and the patient‐parameterized model. The impact of radionuclide biokinetics on marrow dosimetry was not considered. Results Variations in overall bone size play a very minor role in active marrow dose variability. Marrow cellularity is a significant factor in dose variability for active marrow self‐irradiation, but it plays no role for radionuclides localized to the trabecular bone matrix. Variations in trabecular bone volume fractions impact the active marrow dose variability for short‐range particle emitters 45 Ca, 223 Ra, 219 Rn, and 215 Po in the vertebrae and ribs, skeletal sites with small spongiosa proportions of trabecular bone. In the cranium, with its relative high proportion of trabecular bone, significant differences in marrow dosimetry from the reference model were noted for all radionuclides. Conclusions Skeletal models of active marrow dosimetry should be more fully parameterized to permit closer matching to patient bone density and marrow cellularity, particularly when considering short‐range particle emitters localized to either the bone trabeculae or active marrow, respectively.

Geyer, Amy M.↗
DOE OSTI2013

Changes in Bone Mineral Density in Uterine Cervical Cancer Patients After Radiation Therapy

Purpose: To prospectively investigate the changes in bone mineral density (BMD) after pelvic radiation therapy in patients with uterine cervical cancer. Methods and Materials: Of 52 cervical cancer patients who received pelvic RT in our university hospital between 2009 and 2011, 46 patients without recurrence and who were followed up for more than 12 months were included in the study. The BMD of the irradiated region and nonirradiated regions, serum estradiol, tartrate-resistant acid phosphatase-5b, and N-terminal cross-linking telopeptide of collagen 1 were measured before, at 3 months after, and at 12 months after RT. The patient cohort was divided into 2 groups according to estradiol level before RT, and the groups were defined as postmenopausal (<40 pg/mL) and premenopausal (≥40 pg/mL). Results: The mean BMDs within the irradiation field (lumbar vertebra 5) in the postmenopausal and the premenopausal groups were 0.825 and 0.910 g/cm{sup 2} before RT and 0.746 and 0.841 g/cm{sup 2} 12 months after RT, respectively. Significant decreases were observed in both groups (P<.05 and P<.01, respectively). In addition, in the premenopausal group the mean BMDs of the nonirradiated regions at thoracic vertebrae 9-12 and lumbar vertebrae 2-4 were 0.753 and 0.958 g/cm{sup 2} before RT and were significantly decreased to 0.706 and 0.921 g/cm{sup 2} 12 months after RT (P<.01 and P<.05, respectively). Estradiol significantly decreased 3 months after RT, whereas tartrate-resistant acid phosphatase-5b and N-terminal cross-linking telopeptide of collagen 1 continued to increase over time in the premenopausal group. Conclusions: A decrease in BMD in the irradiated region after RT was observed within 1 year, regardless of menopausal status. Furthermore, in premenopausal patients, pelvic RT caused a decrease in systemic BMD.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Bone mineral density and blood metals in premenopausal women

Exposure to metals, specifically cadmium, lead, and mercury, is widespread and is associated with reduced bone mineral density (BMD) in older populations, but the associations among premenopausal women are unclear. Therefore, we evaluated the relationship between these metals in blood and BMD (whole body, total hip, lumbar spine, and non-dominant wrist) quantified by dual energy X-ray absorptiometry in 248 premenopausal women, aged 18-44. Participants were of normal body mass index (mean BMI 24.1), young (mean age 27.4), 60% were white, 20% non-Hispanic black, 15% Asian, and 6% other race group, and were from the Buffalo, New York region. The median (interquartile range) level of cadmium was 0.30 {mu}g/l (0.19-0.43), of lead was 0.86 {mu}g/dl (0.68-1.20), and of mercury was 1.10 {mu}g/l (0.58-2.00). BMD was treated both as a continuous variable in linear regression and dichotomized at the 10th percentile for logistic regression analyses. Mercury was associated with reduced odds of decreased lumbar spine BMD (0.66, 95% confidence interval: 0.44, 0.99), but overall, metals at environmentally relevant levels of exposure were not associated with reduced BMD in this population of healthy, reproductive-aged women. Further research is needed to determine if the blood levels of cadmium, lead, and mercury in this population are sufficiently low that there is no substantive impact on bone, or if effects on bone can be expected only at older ages.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2013

Randomized, Double-Blinded, Placebo-Controlled, Trial of Risedronate for the Prevention of Bone Mineral Density Loss in Nonmetastatic Prostate Cancer Patients Receiving Radiation Therapy Plus Androgen Deprivation Therapy

Purpose: Androgen deprivation therapy (ADT) has been used as an adjuvant treatment to radiation therapy (RT) for the management of locally advanced prostate carcinoma. Long-term ADT decreases bone mineral density (BMD) and increases the risk of osteoporosis. The objective of this clinical trial was to evaluate the efficacy of risedronate for the prevention of BMD loss in nonmetastatic prostate cancer patients undergoing RT plus 2 to 3 years of ADT. Methods and Materials: A double-blinded, placebo-controlled, randomized trial was conducted for nonmetastatic prostate cancer patients receiving RT plus 2 to 3 years of ADT. All had T scores > −2.5 on dual energy x-ray absorptiometry at baseline. Patients were randomized 1:1 between risedronate and placebo for 2 years. The primary endpoints were the percent changes in the BMD of the lumbar spine at 1 and 2 years from baseline, measured by dual energy x-ray absorptiometry. Analyses of the changes in BMD and bone turnover biomarkers were carried out by comparing mean values of the intrapatient changes between the 2 arms, using standard t tests. Results: One hundred four patients were accrued between 2004 and 2007, with 52 in each arm. Mean age was 66.8 and 67.5 years for the placebo and risedronate, respectively. At 1 and 2 years, mean (±SE) BMD of the lumbar spine decreased by 5.77% ± 4.66% and 13.55% ± 6.33%, respectively, in the placebo, compared with 0.12% ± 1.29% at 1 year (P=.2485) and 0.85% ± 1.56% (P=.0583) at 2 years in the risedronate. The placebo had a significant increase in serum bone turnover biomarkers compared with the risedronate. Conclusions: Weekly oral risedronate prevented BMD loss at 2 years and resulted in significant suppression of bone turnover biomarkers for 24 months for patients receiving RT plus 2 to 3 years of ADT.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

High fat diet promotes achievement of peak bone mass in young rats

Highlights: • High fat diet helps in achieving peak bone mass at younger age. • Shifting from high fat to normal diet normalizes obese parameters. • Bone parameters are sustained even after withdrawal of high fat diet. - Abstract: The relationship between obesity and bone is complex. Epidemiological studies demonstrate positive as well as negative correlation between obesity and bone health. In the present study, we investigated the impact of high fat diet-induced obesity on peak bone mass. After 9 months of feeding young rats with high fat diet, we observed obesity phenotype in rats with increased body weight, fat mass, serum triglycerides and cholesterol. There were significant increases in serum total alkaline phosphatase, bone mineral density and bone mineral content. By micro-computed tomography (μ-CT), we observed a trend of better trabecular bones with respect to their microarchitecture and geometry. This indicated that high fat diet helps in achieving peak bone mass and microstructure at younger age. We subsequently shifted rats from high fat diet to normal diet for 6 months and evaluated bone/obesity parameters. It was observed that after shifting rats from high fat diet to normal diet, fat mass, serum triglycerides and cholesterol were significantly decreased. Interestingly, the gain in bone mineral density, bone mineral content and trabecular bone parameters by HFD was retained even after body weight and obesity were normalized. These results suggest that fat rich diet during growth could accelerate achievement of peak bone mass that is sustainable even after withdrawal of high fat diet.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

SU-E-CAMPUS-J-06: The Impact of CT-Scan Energy On Range Uncertainty in Proton Therapy Planning

Purpose: To investigate the impact of tube potential (kVp) on the CTnumber (HU) to proton stopping power ratio (PSPR) conversion table; the range uncertainty and the dosimetric change introduced by a mismatch in kVp between the CT and the HU to PSPR table used to calculate dose are analyzed. Methods: A CIRS CT-ED phantom was scanned with a Philips Brilliance 64-slice scanner under 90kVp and 120kVp tube potentials. Two HU to PSPR curves were then created. Using Eclipse (Varian) a treatment plan was created for a single beam in a water phantom (HU=0) passing through a wedge-shaped heterogeneity (HU=1488). The dose was recalculated by changing only the HU to PSPR table used in the dose calculation. The change in range (the distal 90% isodose line) relative to a distal structure was recorded as a function of heterogeneity thickness in the beam. To show the dosimetric impact of a mismatch in kVp between the CT and the HU to PSPR table, we repeated this procedure using a clinical plan comparing DVH data. Results: The HU to PSPR tables diverge for low-density bone and higher density structures. In the phantom plan, the divergence of the tables results in a change in range of ~1mm per cm of bone in the beam path for the HU used. For the clinical plan, a mismatch in kVp showed a 28% increase in mean dose to the brainstem along with a 10% increase in maximum dose to the brainstem center. Conclusion: A mismatch in kVp between the CT and the HU to PSPR table can introduce significant uncertainty in the proton beam range. For dense bone, the measured range uncertainty is about 1mm per cm of bone in the beam. CT-scan energy verification should be employed, particularly when high-density media is in the proton beam path.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2013

Alleviating anastrozole induced bone toxicity by selenium nanoparticles in SD rats

Aromatase inhibitors like anastrozole play an undisputed key role in the treatment of breast cancer, but on the other hand, various side effects like osteoporosis and increased risk of bone fracture accompany the chronic administration of these drugs. Here we show for the first time that selenium nanoparticles, when given in conjugation to anastrozole, lower the bone toxicity caused by anastrozole and thus reduce the probable damage to the bone. Selenium nanoparticles at a dose of 5 μg/ml significantly reduced the cell death caused by anastrozole (1 μM) in HOS (human osteoblast) cells. In addition, our results also highlighted that in female SD rat model, SeNPs (0.25, 0.5, 1 mg/kg/day) significantly prevented the decrease in bone density and increase in biochemical markers of bone resorption induced by anastrozole (0.2 mg/kg/day) treatment. Histopathological examination of the femurs of SeNP treated group revealed ossification, mineralization, calcified cartilaginous deposits and a marginal osteoclastic activity, all of which indicate a marked restorative action, suggesting the protective action of the SeNPs. Interestingly, SeNPs (1 mg/kg/day) also exhibited protective effect in ovariectomized rat model, by preventing osteoporosis, which signifies that bone loss due to estrogen deficiency can be effectively overcome by using SeNPs. - Highlights: ► SeNPs significantly reduce bone toxicity in anastrozole treated rats. ► SeNPs successfully prevented osteoporosis in ovariectomized rats. ► SeNP treatment lowered the levels of TRAP and increased the levels of ALKP.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2012

X-ray vector radiography imaging for biomedical applications

The non-invasive estimation of fracture risk in osteoporosis remains a challenge in the clinical routine and is mainly based on an assessment of bone density by dual X-ray absorption (DXA) although bone micro-architecture is known to play an important role for bone fragility. Here we report on 'X-ray vector Radiography' measurements able to provide a direct bone microstructure diagnostics on human bone samples, which we compare qualitatively and quantitatively with numerical analysis of high resolution radiographs.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2023

Changes in Distal Tibial Microarchitecture During Eight Weeks of U.S. Army Basic Combat Training Differ by Sex and Race

ABSTRACT Basic combat training (BCT) is a physically rigorous period at the beginning of a soldier's career that induces bone formation in the tibia. Race and sex are determinants of bone properties in young adults but their influences on changes in bone microarchitecture during BCT are unknown. The purpose of this work was to determine the influence of sex and race on changes in bone microarchitecture during BCT. Bone microarchitecture was assessed at the distal tibia via high‐resolution peripheral quantitative computed tomography at the beginning and end of 8 weeks of BCT in a multiracial cohort of trainees (552 female, 1053 male; mean ± standard deviation [SD] age = 20.7 ± 3.7 years) of which 25.4% self‐identified as black, 19.5% as race other than black or white (other races combined), and 55.1% as white. We used linear regression models to determine whether changes in bone microarchitecture due to BCT differed by race or sex, after adjusting for age, height, weight, physical activity, and tobacco use. We found that trabecular bone density (Tb.BMD), thickness (Tb.Th), and volume (Tb.BV/TV), as well as cortical BMD (Ct.BMD) and thickness (Ct.Th) increased following BCT in both sexes and across racial groups (+0.32% to +1.87%, all p < 0.01). Compared to males, females had greater increases in Tb.BMD (+1.87% versus +1.40%; p = 0.01) and Tb.Th (+0.87% versus +0.58%; p = 0.02), but smaller increases in Ct.BMD (+0.35% versus +0.61%; p < 0.01). Compared to black trainees, white trainees had greater increases in Tb.Th (+0.82% versus +0.61%; p = 0.03). Other races combined and white trainees had greater increases in Ct.BMD than black trainees (+0.56% and + 0.55% versus +0.32%; both p ≤ 0.01). Changes in distal tibial microarchitecture, consistent with adaptive bone formation, occur in trainees of all races and sexes, with modest differences by sex and race. Published 2023. This article is a U.S. Government work and is in the public domain in the USA. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Hughes, Julie M.↗
DOE OSTI2018

Adverse physiological and psychological effects of screen time on children and adolescents: Literature review and case study

A growing body of literature is associating excessive and addictive use of digital media with physical, psychological, social and neurological adverse consequences. Research is focusing more on mobile devices use, and studies suggest that duration, content, after-dark-use, media type and the number of devices are key components determining screen time effects. Physical health effects: excessive screen time is associated with poor sleep and risk factors for cardiovascular diseases such as high blood pressure, obesity, low HDL cholesterol, poor stress regulation (high sympathetic arousal and cortisol dysregulation), and Insulin Resistance. Other physical health consequences include impaired vision and reduced bone density. Psychological effects: internalizing and externalizing behavior is related to poor sleep. Depressive symptoms and suicidal are associated to screen time induced poor sleep, digital device night use, and mobile phone dependency. ADHD-related behavior was linked to sleep problems, overall screen time, and violent and fast-paced content which activates dopamine and the reward pathways. Early and prolonged exposure to violent content is also linked to risk for antisocial behavior and decreased prosocial behavior. Psychoneurological effects: addictive screen time use decreases social coping and involves craving behavior which resembles substance dependence behavior. Brain structural changes related to cognitive control and emotional regulation are associated with digital media addictive behavior. A case study of a treatment of an ADHD diagnosed 9-year-old boy suggests screen time induced ADHD-related behavior could be inaccurately diagnosed as ADHD. Screen time reduction is effective in decreasing ADHD-related behavior.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Regulatory inhibition of biological tissue mineralization by calcium phosphate through post-nucleation shielding by fetuin-A

In vertebrates, insufficient availability of calcium and inorganic phosphate ions in extracellular fluids leads to loss of bone density and neuronal hyper-excitability. To counteract this problem, calcium ions are usually present at high concentrations throughout bodily fluids—at concentrations exceeding the saturation point. This condition leads to the opposite situation where unwanted mineral sedimentation may occur. Remarkably, ectopic or out-of-place sedimentation into soft tissues is rare, in spite of the thermodynamic driving factors. This fortunate fact is due to the presence of auto-regulatory proteins that are found in abundance in bodily fluids. Yet, many important inflammatory disorders such as atherosclerosis and osteoarthritis are associated with this undesired calcification. Hence, it is important to gain an understanding of the regulatory process and the conditions under which it can go awry. In this manuscript, we extend mean-field continuum classical nucleation theory of the growth of clusters to encompass surface shielding. We use this formulation to study the regulation of sedimentation of calcium phosphate salts in biological tissues through the mechanism of post-nuclear shielding of nascent mineral particles by binding proteins. We develop a mathematical description of this phenomenon using a countable system of hyperbolic partial differential equations. A critical concentration of regulatory protein is identified as a function of the physical parameters that describe the system.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

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

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 89,90 Sr 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 90 Sr and 89 Sr intake to humans.

59 BASIC BIOLOGICAL SCIENCES↗