Technical Note: Predicting dose distribution with replacing stopping power ratio for inter‐fractional motion and intra‐fractional motion during carbon ion radiotherapy with passive irradiation method for stage I lung cancer
Technical Note: Predicting dose distribution with replacing stopping power ratio for inter‐fractional motion and intra‐fractional motion during carbon ion radiotherapy with passive irradiation method for stage I lung cancer
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技术说明：用替代停止功率比预测 I 期肺癌被动照射碳离子放射治疗过程中分次间运动和分次内运动的剂量分布
DOI：
10.1002/mp.12966
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发表时间：
2018
期刊：
影响因子：
3.8
通讯作者：
Nakano Takashi
中科院分区：
文献类型：
--
作者：
Kubota Yoshiki;Sakai Makoto;Tashiro Mutsumi;Saitoh Jun‐ichi;Abe Takanori;Ohno Tatsuya;Nakano Takashi
PurposeWe设计并评估了一种简单的方法，用于预测在碳离子放射治疗（CIRT）孤立病灶I期肺癌时，分次内和/或分次间运动对剂量分布的影响。用肺的阻止本领比（SPR）代替当前肿瘤区域，用肿瘤的SPR代替移动的肿瘤区域，计算预测剂量分布（PDD）。计算实际剂量分布（ADD），不进行替换。回顾性研究了10例孤立性病变I期肺癌患者，以评估预测方法的准确性。采用骨和肿瘤匹配方法，将4个用于分次内运动的PDD（四维CT期间的门入、呼气、门出、吸气阶段）和2个用于分次间运动的PDD（治疗前1-2天采集的CT图像）与每次CT扫描的6个ADD中的每一个进行比较。计划/临床靶体积（PTV/CTV）接收>95%的处方剂量（V95）和最小剂量覆盖95%的PTV/CTV（D95）的图像与剂量体积直方图参数进行了比较。结果最大肿瘤位移发生在上下方向，上级和下级方向的分数内运动值分别为3.75和8.97 mm，分次间值分别为9.61 mm和4.10 mm。PTV V95关于分次内运动的最大平均误差在门控输出阶段为−0.43%，在吸入阶段为−0.63%。两组间各参数差异无统计学意义（P= 0.541，P = 0.571）。PTV和CTV V95的平均误差分别为2.2%和2.9%，差异无统计学意义（P= 0.387，P = 0.155）。因此，在CIRT期间使用所提出的方法来预测I期孤立病灶肺癌患者肿瘤分次内运动和/或分次间运动的剂量分布是可行的。
PurposeWe designed and evaluated a simple method for predicting the effects of intra‐fractional and/or inter‐fractional motion on dose distribution during carbon ion radiotherapy (CIRT) for solitary‐lesion stage I lung cancer.MethodsThe proposed method uses computed tomography (CT) images from treatment planning and intra‐tumoral and/or inter‐tumoral displacement. The predicted dose distribution (PDD) was calculated by replacing the current tumor region with the stopping power ratio (SPR) of the lung and replacing the moved tumor region with the SPR of the tumor. The actual dose distribution (ADD) was calculated without the replacement. Ten patients with solitary‐lesion stage I lung cancer were retrospectively studied to evaluate the prediction method's accuracy. Four PDDs for intra‐fractional motion (gate‐in, exhalation, gate‐out, inhalation phases during four‐dimensional CT) and two PDDs for inter‐fractional motion (CT images acquired 1–2 days before treatment) with bone‐ and tumor‐matching methods were compared with each of six ADDs on each CT scan. Percentages of the planning/clinical target volumes (PTV/CTV) receiving >95% of the prescribed dose (V95) and of minimum doses covering 95% of the PTV/CTV (D95) were compared with dose volume histogram parameters.ResultsThe maximum tumor displacements occurred in the superior–inferior direction, with intra‐fractional motion values of 3.75 and 8.97 mm for the superior and inferior directions, respectively, and inter‐fractional values of 9.61 and 4.10 mm. The maximum average error for PTV V95regarding intra‐fractional motion was −0.43% for the gate‐out phase and −0.63% for the inhalation phase. There were no significant differences for these parameters (P= 0.541,P= 0.571). Average errors for PTV and CTV V95with inter‐fractional motion with bone matching were 2.2% and 2.9%, respectively, with no significant differences (P= 0.387,P= 0.155).ConclusionsThe accuracy of the proposed method was good. Hence, it is feasible to use the proposed method during CIRT to predict dose distribution with respect to intra‐fractional motion and/or inter‐fractional motion of the tumor in patients with solitary‐lesion stage I lung cancer.
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DOI：
10.1016/j.ejmp.2016.12.018
发表时间：
2017-01-01
影响因子：
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作者：
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