Prostate volumetric-modulated arc therapy: dosimetry and radiobiological model variation between the single-arc and double-arc technique
Prostate volumetric-modulated arc therapy: dosimetry and radiobiological model variation between the single-arc and double-arc technique
复制标题
DOI：
10.1120/jacmp.v14i3.4053
复制
发表时间：
2013-01-01
影响因子：
2.1
通讯作者：
Jiang, Runqing
中科院分区：
文献类型：
--
作者：
Chow, James C. L.;Jiang, Runqing
本研究探讨了单弧技术在前列腺体积调节电弧治疗（VMAT）中加入第二光子弧时剂量学和放射生物学模型的变化。对5例前列腺体积29-68.1 cm的患者进行单弧和双弧前列腺VMAT方案的剂量学和放射生物学模型比较(3)。处方剂量为78 Gy/39分，光子束能量为6 MV。采用单弧和双弧VMAT技术确定剂量-体积直方图、靶区（计划靶区和临床靶区）和正常组织（直肠、膀胱和股骨）的平均和最大剂量、治疗方案中的剂量-体积标准（PTV的D-99%、直肠和膀胱的D-30%、D-50%、V-17Gy和V-35Gy、股骨的D-5%）以及穿过等心的纵、横轴上的剂量分布。为了比较，我们计算了基于RapidArc给药方式的监护单元、前列腺肿瘤控制概率（TCP）和基于Lyman-Burman-Kutcher算法的直肠正常组织并发症概率（NTCP）。研究发现，虽然双弧技术所需的治疗时间几乎是单弧技术的两倍，但双弧方案通过将患者的剂量从前后方向转移到外侧方向，提供了更好的直肠和膀胱剂量-容量标准。由于股骨头比直肠和膀胱放射敏感性低，双弧技术导致前列腺VMAT计划与单弧相比具有更好的前列腺覆盖和直肠剂量-体积标准。双弧组前列腺TCP较单弧组略有升高（0.16%）。因此，当单弧前列腺VMAT计划很难达到直肠剂量-体积标准时，值得考虑双弧技术。
This study investigates the dosimetry and radiobiological model variation when a second photon arc was added to prostate volumetric-modulated arc therapy (VMAT) using the single-arc technique. Dosimetry and radiobiological model comparison between the single-arc and double-arc prostate VMAT plans were performed on five patients with prostate volumes ranging from 29-68.1 cm(3). The prescription dose was 78 Gy/39 fractions and the photon beam energy was 6 MV. Dose-volume histogram, mean and maximum dose of targets (planning and clinical target volume) and normal tissues (rectum, bladder and femoral heads), dose-volume criteria in the treatment plan (D-99% of PTV; D-30%, D-50%, V-17Gy and V-35Gy of rectum and bladder; D-5% of femoral heads), and dose profiles along the vertical and horizontal axis crossing the isocenter were determined using the single-arc and double-arc VMAT technique. For comparison, the monitor unit based on the RapidArc delivery method, prostate tumor control probability (TCP), and rectal normal tissue complication probability (NTCP) based on the Lyman-Burman-Kutcher algorithm were calculated. It was found that though the double-arc technique required almost double the treatment time than the single-arc, the double-arc plan provided a better rectal and bladder dose-volume criteria by shifting the delivered dose in the patient from the anterior-posterior direction to the lateral. As the femoral head was less radiosensitive than the rectum and bladder, the double-arc technique resulted in a prostate VMAT plan with better prostate coverage and rectal dose-volume criteria compared to the single-arc. The prostate TCP of the double-arc plan was found slightly increased (0.16%) compared to the single-arc. Therefore, when the rectal dose-volume criteria are very difficult to achieve in a single-arc prostate VMAT plan, it is worthwhile to consider the double-arc technique.