Whole-Body Voxel-Based Personalized Dosimetry: The Multiple Voxel S-Value Approach for Heterogeneous Media with Nonuniform Activity Distributions
Whole-Body Voxel-Based Personalized Dosimetry: The Multiple Voxel S-Value Approach for Heterogeneous Media with Nonuniform Activity Distributions
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DOI：
10.2967/jnumed.117.201095
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发表时间：
2018-07-01
影响因子：
9.3
通讯作者：
Lee, Jae Sung
中科院分区：
文献类型：
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作者：
Lee, Min Sun;Kim, Joong Hyun;Lee, Jae Sung
随着个体化医学和靶向放射性核素治疗的发展，高精度的个体化剂量测量变得越来越重要。可使用剂量点核或体素S值（VSV）卷积进行基于体素的剂量测定。然而，这些方法没有考虑介质的异质性。在这里，我们提出了一种新的方法，全身基于体素的个性化剂量测定在异质介质与不均匀的活动分布的方法，我们称为多VSV方法。该方法使用多个（N）VSV来覆盖各种密度范围的介质，而不是如在水中发现的仅使用单个VSV。研究方法：使用GATE Monte Carlo模拟预先计算VSV，并将其与时间积分活动进行卷积，以生成密度特定剂量图。进行基于CT的分割以生成每个密度区域的二进制掩模图像。通过N个分段的密度特异性剂量图的总和获得最终剂量图。我们测试了几组具有不同密度的VSV：N = 1（单水VSV）、4、6、8、10和20。为了验证所提出的方法，体模和患者的研究进行了比较，与直接蒙特卡罗方法，这被认为是地面真理。最后，对10例患者进行了剂量测定，使用多VSV方法，并与单VSV和器官为基础的方法进行了比较。报告了8个器官的体素和器官水平错误。结果如下：在体模和患者研究中，多VSV方法显示体素级误差显著降低，尤其是肺部和骨骼区域。随着VSV数量的增加，体素级误差减少，尽管在肺边界观察到一些高估。对于多个VSV（N 5 8），我们实现了体素级误差为2.06%。在剂量学研究中，我们所提出的方法显示出大大改善的结果相比，单一的VSV和器官为基础的剂量学。单VSV、多VSV和基于器官的剂量测量在器官水平的误差分别为-6.71%，2.17%和227.46%。结论：多个VSV方法的异质介质与不均匀的活动分布提供了快速个性化的剂量测定在全身水平，产生的结果相比，直接蒙特卡罗方法。
Personalized dosimetry with high accuracy is becoming more important because of the growing interest in personalized medicine and targeted radionuclide therapy. Voxel-based dosimetry using dose point kernel or voxel S-value (VSV) convolution is available. However, these approaches do not consider the heterogeneity of the medium. Here, we propose a new method for whole-body voxel-based personalized dosimetry in heterogeneous media with nonuniform activity distributions-a method we refer to as the multiple VSV approach. Instead of using only a single VSV, as found in water, the method uses multiple numbers (N) of VSVs to cover media of various density ranges, as found in the whole body. Methods: The VSVs were precalculated using GATE Monte Carlo simulation and were convoluted with the time-integrated activity to generate density-specific dose maps. CT-based segmentation was performed to generate a binary mask image for each density region. The final dose map was acquired by the summation of N segmented density-specific dose maps. We tested several sets of VSVs with different densities: N = 1 (single water VSV), 4, 6, 8, 10, and 20. To validate the proposed method, phantom and patient studies were conducted and compared with the direct Monte Carlo approach, which was considered the ground truth. Finally, dosimetry on 10 patients was performed using the multiple VSV approach and compared with the single VSV and organ-based approaches. Errors at the voxel and organ levels were reported for 8 organs. Results: In the phantom and patient studies, the multiple VSV approach showed significant decreases in voxel-level errors, especially for the lung and bone regions. As the number of VSVs increased, voxel-level errors decreased, although some overestimations were observed at the lung boundaries. For the multiple VSVs (N 5 8), we achieved a voxel-level error of 2.06%. In the dosimetry study, our proposed method showed greatly improved results compared with single VSV and organ-based dosimetry. Errors at the organ level were -6.71%, 2.17%, and 227.46% for single VSV, multiple VSV, and organ-based dosimetry, respectively. Conclusion: The multiple VSV approach for heterogeneous media with nonuniform activity distributions offers fast personalized dosimetry at the whole-body level, yielding results comparable to those of the direct Monte Carlo approach.