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首页> 外文期刊>Medical Physics >Experimental verification of the Acuros XB and AAA dose calculation adjacent to heterogeneous media for IMRT and RapidArc of nasopharygeal carcinoma
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Experimental verification of the Acuros XB and AAA dose calculation adjacent to heterogeneous media for IMRT and RapidArc of nasopharygeal carcinoma

机译：鼻咽癌IMRT和RapidArc邻近异质介质的Acuros XB和AAA剂量计算的实验验证

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摘要

Purpose: To compare the doses calculated by the Acuros XB (AXB) algorithm and analytical anisotropic algorithm (AAA) with experimentally measured data adjacent to and within heterogeneous medium using intensity modulated radiation therapy (IMRT) and RapidArc~R (RA) volumetric arc therapy plans for nasopharygeal carcinoma (NPC).Methods: Two-dimensional dose distribution immediately adjacent to both air and bone inserts of a rectangular tissue equivalent phantom irradiated using IMRT and RA plans for NPC cases were measured with GafChromic~R EBT3 films. Doses near and within the nasopharygeal (NP) region of an anthropomorphic phantom containing heterogeneous medium were also measured with thermo-luminescent dosimeters (TLD) and EBT3 films. The measured data were then compared with the data calculated by AAA and AXB. For AXB, dose calculations were performed using both dose-to-medium (AXB_D_m) and dose-to-water (AXB_D_W) options. Furthermore, target dose differences between AAA and AXB were analyzed for the corresponding real patients. The comparison of real patient plans was performed by stratifying the targets into components of different densities, including tissue, bone, and air.Results: For the verification of planar dose distribution adjacent to air and bone using the rectangular phantom, the percentages of pixels that passed the gamma analysis with the ± 3%/3mm criteria were 98.7%, 99.5%, and 97.7% on the axial plane for AAA, AXB_D_m, and AXB_DW, respectively, averaged over all IMRT and RA plans, while they were 97.6%, 98.2%, and 97.7%, respectively, on the coronal plane. For the verification of planar dose distribution within the NP region of the anthropomorphic phantom, the percentages of pixels that passed the gamma analysis with the ± 3%/3mm criteria were 95.1%, 91.3%, and 99.0% for AAA, AXB_D_m, and AXB_D_W, respectively, averaged over all IMRT and RA plans. Within the NP region where air and bone were present, the film measurements represented the dose close to unit density water in a heterogeneous medium, produced the best agreement with the AXB_D_W. For the verification of point doses within the target using TLD in the anthropomorphic phantom, the absolute percentage deviations between the calculated and measured data when averaged over all IMRT and RA plans were 1.8%, 1.7%, and 1.8% for AAA, AXB_D_m and AXB_D_W, respectively. From all the verification results, no significant difference was found between the IMRT and RA plans. The target dose analysis of the real patient plans showed that the discrepancies in mean doses to the PTV component in tissue among the three dose calculation options were within 2%, but up to about 4% in the bone content, with AXB_D_m giving the lowest values and AXB_D_W giving the highest values.Conclusions: In general, the verification measurements demonstrated that both algorithms produced acceptable accuracy when compared to the measured data. GafChromic~R film results indicated that AXB produced slightly better accuracy compared to AAA for dose calculation adjacent to and within the heterogeneous media. Users should be aware of the differences in calculated target doses between options AXB_D_m and AXB_D_W, especially in bone, for IMRT and RA in NPC cases.
机译：目的：比较使用强度调制放射疗法（IMRT）和RapidArc〜R（RA）体积电弧疗法将Acuros XB（AXB）算法和解析各向异性算法（AAA）计算出的剂量与异质介质附近和内部的实验测量数据进行比较方法：用GafChromic〜R EBT3膜测量IMRT和RA计划对NPC病例照射的矩形组织等效体模的空气和骨骼插入物的紧邻空气和骨插入物的二维剂量分布。还使用热发光剂量计（TLD）和EBT3膜测量了含有拟人化体模的异质介质的鼻咽（NP）区域附近和内部的剂量。然后将测得的数据与AAA和AXB计算的数据进行比较。对于AXB，使用剂量对介质（AXB_D_m）和剂量对水（AXB_D_W）选项进行剂量计算。此外，针对相应的真实患者分析了AAA和AXB之间的目标剂量差异。通过将目标分层为不同密度的组成部分（包括组织，骨骼和空气）来进行实际患者计划的比较。结果：为了使用矩形体模验证与空气和骨骼相邻的平面剂量分布，像素百分比在所有IMRT和RA计划中，通过AAA，AXB_D_m和AXB_DW的轴上的±3％/ 3mm标准的伽玛分析的平均值分别为98.7％，99.5％和97.7％，而它们分别为97.6％，在冠状平面上分别为98.2％和97.7％。为了验证拟人化模型的NP区域内的平面剂量分布，对于AAA，AXB_D_m和AXB_D_W，通过±3％/ 3mm标准的伽马分析的像素百分比分别为95.1％，91.3％和99.0％分别在所有IMRT和RA计划中取平均值。在存在空气和骨骼的NP区域内，薄膜测量值代表了在异质介质中接近单位密度水的剂量，与AXB_D_W产生了最好的一致性。为了在拟人化体模中使用TLD验证目标内的点剂量，对于所有IMRT和RA计划，AAA，AXB_D_m和AXB_D_W的所有IMRT和RA计划取平均值时，计算数据和测量数据之间的绝对百分比偏差分别为1.8％，1.7％和1.8％ ， 分别。从所有验证结果来看，IMRT和RA计划之间没有发现显着差异。实际患者计划的目标剂量分析显示，三种剂量计算选项中，组织中PTV成分的平均剂量差异在2％以内，但骨含量最高可达4％，其中AXB_D_m的数值最低结论：总的来说，验证测量结果表明，与测量数据相比，两种算法都能产生可接受的精度。 GafChromic〜R胶片结果表明，与AAA相比，AXB在异质介质附近和内部产生的剂量计算精度更高。用户应注意，对于NPC病例中的IMRT和RA，选项AXB_D_m和AXB_D_W之间的计算目标剂量之间存在差异，尤其是在骨骼中。

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