Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina, USA.
Int J Radiat Oncol Biol Phys. 2010 Sep 1;78(1):288-96. doi: 10.1016/j.ijrobp.2009.10.036. Epub 2010 May 3.
To investigate the technical feasibility of volumetric modulated arc therapy (V-MAT) in the delivery of partial breast irradiation (PBI).
V-MAT and the standard, three-dimensional conformal radiotherapy (3D-CRT), were compared retrospectively in 8 patients previously treated with PBI. These patients' plans were replanned with a single partial arc using V-MAT that included partial blocking to minimize normal tissue dose. Dosimetric parameters were calculated to evaluate plan quality. Quality assurance studies included verifying both the point and the multiple planar doses. Total monitor units and delivery time were also evaluated, and collision clearance was analyzed.
Volumes of ipsilateral lung irradiated to 10 Gy (V10) and 20 Gy (V20) by V-MAT were significantly less than those of 3D-CRT (p = 0.03 for V10 and p = 0.025 for V20). The volume of ipsilateral breast irradiated to 5 Gy was significantly less by using V-MAT than with 3D-CRT (p = 0.02), with a ratio of integrated dose of <1.00. The total mean monitor units (489 +/- 38) for V-MAT were significantly less than those for 3D-CRT (634 +/- 123) (p = 0.017), with a 23% reduction. The average machine delivery time was 1.21 +/- 0.10 min for the V-MAT plans and 6.28 +/- 1.40 min for the 3D-CRT plans, resulting in a reduction factor of 80.1%. The conformity indexes were 1.3 in the V-MAT plans and 1.5 in the 3D-CRT plans (p = 0.102).
V-MAT technology is feasible for PBI patients. Compared to a conventional 3D-CRT technique, it is more efficient, offers equivalent or better dose conformity, delivers lower doses to the ipsilateral lung and breast, and may potentially reduce intrafractional motion.
研究容积调强弧形治疗（VMAT）在部分乳房照射（PBI）中的技术可行性。
回顾性比较了 8 例接受 PBI 治疗的患者的 VMAT 和标准的三维适形放疗（3D-CRT）。这些患者的计划使用单弧 VMAT 进行重新规划，包括部分阻断以最小化正常组织剂量。计算剂量学参数以评估计划质量。质量保证研究包括验证点剂量和多个平面剂量。还评估了总监测单位和输送时间，并分析了碰撞清除。
VMAT 照射的同侧肺 10 Gy（V10）和 20 Gy（V20）体积明显小于 3D-CRT（V10 时 p = 0.03，V20 时 p = 0.025）。使用 VMAT 照射的同侧乳房 5 Gy 体积明显小于 3D-CRT（p = 0.02），积分剂量比<1.00。VMAT 的总平均监测单位（489 +/- 38）明显小于 3D-CRT（634 +/- 123）（p = 0.017），减少了 23%。VMAT 计划的平均机器输送时间为 1.21 +/- 0.10 分钟，3D-CRT 计划的平均机器输送时间为 6.28 +/- 1.40 分钟，减少了 80.1%。VMAT 计划的适形指数为 1.3，3D-CRT 计划的适形指数为 1.5（p = 0.102）。
VMAT 技术对 PBI 患者是可行的。与传统的 3D-CRT 技术相比，它更有效，提供等效或更好的剂量适形性，对同侧肺和乳房的剂量更低，并且可能降低分次内运动。
