A three-dimensional transport model for determining absorbed fractions of energy for electrons within trabecular bone.
A three-dimensional transport model for determining absorbed fractions of energy for electrons within trabecular bone.
复制标题
用于确定骨小梁内电子吸收能量分数的三维传输模型。
作者：
L. Bouchet;D. Jokisch;W. Bolch
未标记
骨髓通常是放射免疫治疗和放射性核素缓解骨痛中关注的剂量限制器官。然而，骨骼剂量测定是复杂的，其微观结构的复杂性，这可能会有很大的不同，在整个骨骼区域。在这篇文章中，介绍了一种新的三维电子传输模型的松质骨，基于Monte Carlo传输和骨微结构信息的几个松质骨网站。
方法
最初由Spiers等人发表的骨髓腔和骨小梁弦长分布被随机取样，以在单电子的三维传输期间创建骨、骨内膜和骨髓的交替区域。对于骨髓空间，在基于每个区域中活性和非活性骨髓百分比的转运计算中明确考虑了部位特异性元素组成。电子输运用EGS 4电子输运程序和参数简化的电子步输运算法进行。将7个成人骨小梁部位的电子吸收能量分数制成表格，考虑3个源和靶区域：骨小梁骨髓腔（TMS）、骨小梁骨内膜（TBE）和骨小梁体积（TBV）。
结果
对于所有的源-靶组合，被吸收的分数被认为是在骨骼内变化很大。这些变化可以直接归因于不同骨骼区域的骨小梁显微结构的差异。对于许多源-目标组合，在计算的吸收分数中看到了大量的能量依赖性，这是国际辐射防护委员会（ICRP）推荐的值中没有考虑的因素。还开发了基于范围-能量关系的松质骨中电子传输的一维模型，以验证三维传输模型并评估两种建模方法之间的差异。观察到大约10%-15%的差异，特别是在低电子能量下。在TBV源和TMS靶的情况下（或反之亦然），在吸收分数中观察到>50%的差异。
结论
骨小梁中电子传递的三维模型允许改进骨骼吸收分数的估计。该模型突出了区域和能源的依赖性的吸收分数以前没有考虑在ICRP模型。
UNLABELLED
Bone marrow is generally the dose-limiting organ of concern in radioimmunotherapy and in radionuclide palliation of bone pain. However, skeletal dosimetry is complicated by the intricate nature of its microstructure, which can vary greatly throughout skeletal regions. In this article, a new three-dimensional electron transport model for trabecular bone is introduced, based on Monte Carlo transport and on bone microstructure information for several trabecular bone sites.
METHODS
Marrow cavity and trabecular chord length distributions originally published by Spiers et al. were randomly sampled to create alternating regions of bone, endosteum and marrow during the three-dimensional transport of single electrons. For the marrow spaces, explicit consideration of the site-specific elemental composition was made in the transport calculations based on the percentage of active and inactive marrow in each region. The electron transport was performed with the EGS4 electron transport code and the parameter reduced electron-step transport algorithm. Electron absorbed fractions of energy were tabulated for seven adult trabecular bone sites, considering three source and target regions: the trabecular marrow space (TMS), the trabecular bone endosteum (TBE) and the trabecular bone volume (TBV).
RESULTS
For all source-target combinations, the absorbed fraction was seen to vary widely within the skeleton. These variations can be directly attributed to the differences in the trabecular microstructure of the different skeletal regions. For many source-target combinations, substantial energy dependence was seen in the calculated absorbed fraction, a factor not considered in values recommended by the International Commission on Radiological Protection (ICRP). A one-dimensional model of electron transport in trabecular bone, based on range-energy relationships, was also developed to verify the three-dimensional transport model and to evaluate differences between the two modeling approaches. Differences of approximately 10%-15% were seen, particularly at low electron energies. In the case of a TBV source and a TMS target (or vice versa), differences >50% were seen in the absorbed fraction.
CONCLUSION
The three-dimensional model of electron transport in trabecular bone allows improved estimates of skeletal absorbed fractions. The model highlights both the regional and the energy dependency of the absorbed fraction not previously considered in the ICRP model.
铼-186(Sn)-HEDP 对转移性骨骼肿瘤辐射剂量的蒙特卡罗模拟模型。
DOI：
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发表时间：
1995
期刊：
Journal of nuclear medicine : official publication, Society of Nuclear Medicine.
影响因子：
--
作者：
Samaratunga,RC;Thomas,SR;Hinnefeld,JD;VonKuster,LC;Hyams,DM;Moulton,JS;Sperling,MI;Maxon3rd,HR
通讯作者：
Maxon3rd,HR
选择放射性药物缓解转移性骨病变骨痛的考虑因素。
DOI：
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发表时间：
2000
期刊：
Journal of nuclear medicine : official publication, Society of Nuclear Medicine.
影响因子：
--
作者：
Bouchet,LG;Bolch,WE;Goddu,SM;Howell,RW;Rao,DV
通讯作者：
Rao,DV