Effect of Voxel Size and Computation Method on Tc-99m MAA SPECT/CT-Based Dose Estimation for Y-90 Microsphere Therapy
Effect of Voxel Size and Computation Method on Tc-99m MAA SPECT/CT-Based Dose Estimation for Y-90 Microsphere Therapy
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DOI：
10.1109/tmi.2009.2022753
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发表时间：
2009-11-01
影响因子：
10.6
通讯作者：
Erwin, William D.
中科院分区：
文献类型：
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作者：
Pasciak, Alexander S.;Erwin, William D.
用Y-90标记的微球选择性内照射治疗肝细胞癌和肝转移癌已成为一种有效和广泛使用的治疗方案。然而，这种治疗的剂量学评估仍然是原始的，因为通常只使用基于注入活度的均匀分布模型。这项研究试图量化几种复杂的针对患者的技术的有效性，这些技术利用TC-99m MAA模拟研究的源分布来执行体素剂量计算。这些技术包括基于CT的体素体素模型中完整的蒙特卡罗辐射传输计算、患者特定体素模型中的局部能量沉积以及水中的核传输技术。使用三种不同的体素尺寸和SPECT重建矩阵大小对每种技术进行评估。所有方法的剂量评估结果都与使用全三维蒙特卡罗模拟获得的精确解进行了比较，其中源分布不是基于SPECT数据，而是基于研究中使用的拟人体模的注入活动和精确边界。研究结果表明，在体素较大的情况下，使用小矩阵的SPECT重建(×)，蒙特卡罗方法和局部沉积方法几乎是相同的。然而，使用较大的SPECT重建矩阵(256×256)，局部沉积方法明显比全三维蒙特卡罗传输方法更精确，并且计算量可以忽略不计。
The use of selective internal radiation therapy for treatment of hepatocellular carcinoma and liver metastases using Y-90 labeled microspheres has become an effective and widely used treatment regimen. However, dosimetric evaluations of this treatment are still primitive as uniform distribution models based only on injected activity are often used. This investigation attempts to quantify the effectiveness of several sophisticated patient-specific techniques which utilize the source distribution of Tc-99m MAA simulation studies to perform voxelized dosimetric computations. Among these techniques are complete Monte-Carlo radiation transport computation in patient-specific CT-based voxel phantoms, local energy deposition in patient specific phantoms and kernel transport techniques in water. Each technique was evaluated using three different phantom voxel dimensions and SPECT reconstruction matrix sizes. Dose evaluation results using all methods were compared to the exact solution, obtained using fully 3-D Monte-Carlo simulations with source distribution based not on SPECT data, but on the injected activity and exact boundaries of the anthropomorphic phantom used in the study. The results of this study show that at large voxel sizes and using SPECT reconstructions with a small matrix size (64 x 64), Monte-Carlo and local deposition methods are nearly equivalent. However, using a large SPECT reconstruction matrix (256 x 256) the local deposition method is significantly more accurate than full 3-D Monte-Carlo transport, and with a negligible computational burden.