Computational lymphatic node models in pediatric and adult hybrid phantoms for radiation dosimetry.
Computational lymphatic node models in pediatric and adult hybrid phantoms for radiation dosimetry.
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DOI：
10.1088/0031-9155/58/5/n59
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发表时间：
2013-03-07
影响因子：
3.5
通讯作者：
Moroz BE
中科院分区：
文献类型：
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作者：
Lee C;Lamart S;Moroz BE
我们为6个儿童和2个成人混合计算模型开发了淋巴结模型，以计算来自外部和内部辐射暴露的淋巴结剂量估计值。我们根据国际辐射防护委员会（ICRP）出版物23和89中的建议，在16个淋巴结簇位置得出淋巴结数量：胸外，颈，胸（上下），乳房（左右），肠系膜（左和右），腋窝（左右），肘（左侧和右侧）、腹股沟（左侧和右侧）和腘动脉（左侧和右侧），适用于不同年龄（新生儿、1岁、5岁、10岁、15岁和成人）。我们通过假设所有节点具有相同的大小，除了狭窄的集群网站来自已发表的数据，模拟每个淋巴结的混合体素格式内。通过以下算法生成淋巴结：（1）在16个簇位点中选择淋巴结位点;（2）在以所选簇位点为中心的球形空间内随机采样淋巴结位置;（3）基于ICRP出版物23和89中定义的淋巴结特征创建代表淋巴结的组织球体或卵形体。我们创建淋巴结，直到达到所选簇部位的预定义淋巴结数量。该算法适用于体素化后的儿科（新生儿、1岁、5岁和10岁男性以及15岁男性）和成年男性和女性符合ICRP的混合体模。为了评估我们的内部剂量测定模型的性能，我们使用MCNPX2.6（一种经过充分验证的蒙特卡罗辐射传输代码）计算了分布在6个淋巴结簇部位的碘-131选定器官和组织的剂量转换系数（称为S值）。我们对计算结果的分析表明，S值受淋巴结簇位置的显著影响，并且由于与较大体模相比器官间距离较短，较小体模的S值增加。通过测试S值对随机采样和体素分辨率的敏感性，我们证实了淋巴结模型对于不同的随机采样和体素分辨率是合理稳定和一致的。
We developed models of lymphatic nodes for 6 pediatric and 2 adult hybrid computational phantoms to calculate the lymphatic node dose estimates from external and internal radiation exposures. We derived the number of lymphatic nodes from the recommendations in International Commission on Radiological Protection (ICRP) Publications 23 and 89 at 16 cluster locations for the lymphatic nodes: extrathoracic, cervical, thoracic (upper and lower), breast (left and right), mesentery (left and right), axillary (left and right), cubital (left and right), inguinal (left and right), and popliteal (left and right), for different ages (newborn, 1-, 5-, 10-, 15-year-old, and adult). We modeled each lymphatic node within the voxel format of the hybrid phantoms by assuming that all nodes have identical size derived from published data except narrow cluster sites. The lymph nodes were generated by the following algorithm: (1) selection of the lymph node site among the 16 cluster sites; (2) random sampling of the location of the lymph node within a spherical space centered at the chosen cluster site; (3) creation of the sphere or ovoid of tissue representing the node based on lymphatic node characteristics defined in ICRP Publications 23 and 89. We created lymph nodes until the pre-defined number of lymphatic nodes at the selected cluster site was reached. This algorithm was applied to pediatric (newborn, 1-, 5-, and 10-year-old male, and 15-year-old males) and adult male and female ICRP-compliant hybrid phantoms after voxelization. To assess the performance of our models for internal dosimetry, we calculated dose conversion coefficients, called S values, for selected organs and tissues with Iodine-131 distributed in 6 lymphatic node cluster sites using MCNPX2.6, a well validated Monte Carlo radiation transport code. Our analysis of the calculations indicates that the S values were significantly affected by the location of the lymph node clusters and that the values increased for smaller phantoms due to the shorter inter-organ distances compared to the bigger phantoms. By testing sensitivity of S values to random sampling and voxel resolution, we confirmed that the lymph node model is reasonably stable and consistent for different random samplings and voxel resolutions.