Evaluation of correlation between intrafractional residual setup errors and accumulation of delivered dose distributions in single isocenter volumetric modulated arc therapy for multiple brain metastases
Evaluation of correlation between intrafractional residual setup errors and accumulation of delivered dose distributions in single isocenter volumetric modulated arc therapy for multiple brain metastases
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DOI：
10.1016/j.ejmp.2022.04.012
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发表时间：
2022-04-28
影响因子：
3.4
通讯作者：
Mizowaki, Takashi
中科院分区：
文献类型：
--
作者：
Tsuruta, Yusuke;Nakamura, Mitsuhiro;Mizowaki, Takashi
目的：评价病灶内残余设置误差（RSEs）引起的总肿瘤体积（GTV）位置偏移，并积累考虑病灶内残余设置误差的分割立体定向放疗（f-SRT）联合单等中心体积调节电弧治疗（SI-VMAT）治疗多发性脑转移的剂量分布。方法：总共纳入了72例连续接受f-SRT联合SI-VMAT治疗多发性脑转移的患者。所有患者均使用ExacTrac x射线（ETX）系统进行6D矫正。考虑ETX系统在辐照过程中测量的rse，计算GTV位移（AD）。分析了AD与等中心到各GTV的距离(d)的相关性。对5例AD患者（bbb1mm）生成考虑病灶内RSEs的CT图像。在相应的CT上重建各组分的剂量分布，然后进行累积。结果：417个gtv的7270个中心位置的AD的第95百分位为0.92 mm。AD与d之间无相关性。在5例AD患者的53 GTV中，GTV D99.5%和D0.5%在计划值和累积值之间的差异分别为-0.4 +/- 2.5%和-1.0 +/- 0.8%。D99.5%和D0.5%的GTV差异与d无相关性。结论：尽管GTV的位置远离等中心，但我们发现GTV的D99.5%和D0.5%无显著差异。然而，值得注意的是，这一结果是由于术中RSEs降低到临床可接受的水平。
Purpose: To evaluate the displacement of gross tumor volume (GTV) positions caused by intrafractional residual setup errors (RSEs) and to accumulate delivered dose distributions considering intrafraction RSEs in fractionatedstereotactic radiotherapy (f-SRT) with single isocenter volumetric modulated arc therapy (SI-VMAT) for multiple brain metastases.Methods: Overall, 72 consecutive patients who underwent f-SRT with SI-VMAT for multiple brain metastases were included. For all patients, 6D correction was performed using the ExacTrac X-ray (ETX) system. GTV displacement (AD) was calculated considering the intrafractional RSEs measured by the ETX system during irradiation. The correlation between AD and the distance from the isocenter to each GTV (d) was analyzed. Computed tomography (CT) images considering the intrafractional RSEs were generated for five patients with AD > 1 mm. The delivered dose distributions for all fractions were reconstructed on the corresponding CT, followed by their accumulation.Results: The 95th percentile of AD from 7,270 resultant center positions of 417 GTVs was 0.92 mm. No correlation was observed between AD and d. For 53 GTVs from five patients with AD > 1 mm, the difference of GTV D99.5% and D0.5% between the planned and accumulated values was -0.4 +/- 2.5% and -1.0 +/- 0.8%, respectively. There was no correlation between d and the difference of GTV D99.5% and D0.5%.Conclusions: We found no significant difference in GTV D99.5% and D0.5%, despite the location of GTVs far from the isocenter. However, it should be noted that this result was because the intrafractional RSEs were reduced to a clinically acceptable level.