Dosimetric effect due to the motion during deep inspiration breath hold for left-sided breast cancer radiotherapy
Dosimetric effect due to the motion during deep inspiration breath hold for left-sided breast cancer radiotherapy
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DOI：
10.1120/jacmp.v16i4.5358
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发表时间：
2015-01-01
影响因子：
2.1
通讯作者：
Marks, Lawrence
中科院分区：
文献类型：
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作者：
Tang, Xiaoli;Cullip, Tim;Marks, Lawrence
左侧乳腺癌的深吸气屏气（DIBH）放射治疗可以减少心脏暴露和内部运动。我们修改了我们的内部治疗计划系统（TPS），以回顾性分析屏气运动日志文件，计算屏气期间运动的剂量效应。研究了30例使用AlignRT治疗的左侧仰卧位DIBH乳腺患者。记录屏气运动-治疗表面的三个平移和三个旋转位移-真实的时间增量（RTD）。使用RTD的射束开启部分估计相应的输送剂量。每次运动用于计算剂量，最终估计剂量是多次所得剂量的等加权平均值。30例患者中有10例有目的地将内乳淋巴结（IMN）纳入切线野，我们评估了40戈伊覆盖的IMN百分比。比较了计划和实施的心脏平均剂量、肺V20（接受> 20戈伊的肺体积）、40戈伊覆盖的IMN百分比和IMN平均剂量。绝对RTD的射束开启部分的平均值和标准差分别为0.81 +/- 1.29 mm、0.68 +/- 0.85 mm、0.76 +/- 0.85 mm、0.96度+/- 0.49度、0.93度+/- 0.43度和1.03度+/- 0.50度，垂直、纵向、分别为横向、偏航、滚转和俯仰。平均计划和输送的平均心脏剂量分别为99和101 cGy。肺V20分别为6.59%和6.74%。IMN 40戈伊覆盖率为83%和77%，平均IMN剂量为4642和4518 c戈伊。DIBH期间的平均运动小于1 mm和1度，这反映了患者屏气的相对再现性。平均而言，平均心脏剂量和肺V20合理地接近计划的剂量。IMN 40戈伊的覆盖率在某些情况下可能会适度降低。
Deep inspiration breath-hold (DIBH) radiotherapy for left-sided breast cancer can reduce cardiac exposure and internal motion. We modified our in-house treatment planning system (TPS) to retrospectively analyze breath-hold motion log files to calculate the dosimetric effect of the motion during breath hold. Thirty left-sided supine DIBH breast patients treated using AlignRT were studied. Breath-hold motion was recorded - three translational and three rotational displacements of the treatment surface - the Real Time Deltas (RTD). The corresponding delivered dose was estimated using the beam-on portions of the RTDs. Each motion was used to calculate dose, and the final estimated dose was the equally weighted average of the multiple resultant doses. Ten of thirty patients had internal mammary nodes (IMN) purposefully included in the tangential fields, and we evaluated the percentage of IMN covered by 40 Gy. The planned and delivered heart mean dose, lungs V20 (volume of the lungs receiving > 20 Gy), percentage of IMN covered by 40 Gy, and IMN mean dose were compared. The averaged mean and standard deviation of the beam-on portions of the absolute RTDs were 0.81 +/- 1.29 mm, 0.68 +/- 0.85 mm, 0.76 +/- 0.85 mm, 0.96 degrees +/- 0.49 degrees, 0.93 degrees +/- 0.43 degrees, and 1.03 degrees +/- 0.50 degrees, for vertical, longitudinal, lateral, yaw, roll, and pitch, respectively. The averaged planned and delivered mean heart dose were 99 and 101 cGy. Lungs V20 were 6.59% and 6.74%. IMN 40 Gy coverage was 83% and 77%, and mean IMN dose was 4642 and 4518 cGy. The averaged mean motion during DIBH was smaller than 1 mm and 1 degrees, which reflects the relative reproducibility of the patient breath hold. On average, the mean heart dose and lungs V20 were reasonably close to what have been planned. IMN 40 Gy coverage might be modestly reduced for certain cases.