Introduction: Dose validation inside the human body needs a medium which can simulate the actual heterogeneities of a specific body site. The aim of the present work is to study the properties of a cost-effective heterogeneous thorax phantom (HTP) developed in-house by the author and its application for the evaluation of patient-specific absolute point dosimetry by employing analytic anisotropic algorithm (AAA) and Acuros XB (AXB) algorithm.
Materials and Methods: HTP was made from the dust of porous pinewood, rib cage, and honeybee's wax. Density and central axis isodose depth distribution was measured on computed tomography images of actual patient and on HTP. Absolute point dose verification of 35 patients was done using AAA and AXB algorithm. The difference in the calculated dose by AAA and AXB was compared using the Wilcoxon signed-rank test.
Results: Density distribution and central axis depth dose inside the HTP compare well with that of an actual patient. The mean percentage variation between the planned and the measured doses inside the HTP was found to be 4.85 (standard deviation [SD] = 3.38) and 1.3 (SD = 2.93), respectively, using AAA and AXB algorithm. The difference in the measured dose and the planned dose was found to be significant for AAA with the significance level of 0.01 (p-value < 0.00001), whereas it was found to be insignificant (p-value < 0.00001) for AXB.
Conclusion: The results of this study showed that the HTP is resembled with the human thorax in terms of its heterogeneities and radiological properties and can be used for pretreatment plan verification.


中文翻译：

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通过分析各向异性算法和 Acuros XB 算法验证绝对点剂量测定，在内部开发具有成本效益的异质胸部模型


简介：人体内的剂量验证需要一种能够模拟特定身体部位的实际异质性的介质。本工作的目的是研究作者内部开发的具有成本效益的异质胸腔体模 (HTP) 的特性及其在采用分析各向异性算法 (AAA) 评估患者特定绝对点剂量学中的应用和 Acuros XB (AXB) 算法。
材料和方法：HTP 是由多孔松木、肋骨和蜜蜂蜡的灰尘制成的。在实际患者的计算机断层扫描图像和 HTP 上测量密度和中心轴等剂量深度分布。使用 AAA 和 AXB 算法对 35 名患者进行绝对点剂量验证。使用 Wilcoxon 符号秩检验比较 AAA 和 AXB 计算剂量的差异。
结果：HTP 内的密度分布和中心轴深度剂量与实际患者的比较好。使用 AAA 和 AXB 算法，发现 HTP 内计划剂量和测量剂量之间的平均百分比变化分别为 4.85（标准偏差 [SD] = 3.38）和 1.3（SD = 2.93）。发现测量剂量和计划剂量的差异对于 AAA 具有显着性，显着性水平为 0.01（p 值 < 0.00001），而对于 AXB ，发现不显着（p 值 < 0.00001）。
结论：本研究结果表明，HTP在异质性和放射学特性方面与人胸腔相似，可用于预处理方案验证。