Qiu Jian-Jian, Chang Zheng, Horton Janet K, Wu Qing-Rong Jackie, Yoo Sua, Yin Fang-Fang
Department of Radiation Oncology, Duke University Medical Center, Durham, NC; Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai, China; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China.
Department of Radiation Oncology, Duke University Medical Center, Durham, NC.
Med Dosim. 2014 Summer;39(2):152-8. doi: 10.1016/j.meddos.2013.12.001. Epub 2014 Jan 27.
The purpose is to dosimetrically compare the following 3 delivery techniques: 3-dimensional conformal radiation therapy (3D-CRT), intensity-modulated arc therapy (IMRT), and volumetric-modulated arc therapy (V-MAT) in the treatment of accelerated partial-breast irradiation (APBI). Overall, 16 patients with T1/2N0 breast cancer were treated with 3D-CRT (multiple, noncoplanar photon fields) on the RTOG 0413 partial-breast trial. These cases were subsequently replanned using static gantry IMRT and V-MAT technology to understand dosimetric differences among these 3 techniques. Several dosimetric parameters were used in plan quality evaluation, including dose conformity index (CI) and dose-volume histogram analysis of normal tissue coverage. Quality assurance studies including gamma analysis were performed to compare the measured and calculated dose distributions. The IMRT and V-MAT plans gave more conformal target dose distributions than the 3D-CRT plans (p < 0.05 in CI). The volume of ipsilateral breast receiving 5 and 10Gy was significantly less using the V-MAT technique than with either 3D-CRT or IMRT (p < 0.05). The maximum lung dose and the ipsilateral lung volume receiving 10 (V10) or 20Gy (V20) were significantly less with both V-MAT and IMRT (p < 0.05). The IMRT technique was superior to 3D-CRT and V-MAT of low dose distributions in ipsilateral lung (p < 0.05 in V5 and D5). The total mean monitor units (MUs) for V-MAT (621.0 ± 111.9) were 12.2% less than those for 3D-CRT (707.3 ± 130.9) and 46.5% less than those for IMRT (1161.4 ± 315.6) (p < 0.05). The average machine delivery time was 1.5 ± 0.2 minutes for the V-MAT plans, 7.0 ± 1.6 minutes for the 3D-CRT plans, and 11.5 ± 1.9 minutes for the IMRT plans, demonstrating much less delivery time for V-MAT. Based on this preliminary study, V-MAT and IMRT techniques offer improved dose conformity as compared with 3D-CRT techniques without increasing dose to the ipsilateral lung. In terms of MU and delivery time, V-MAT is significantly more efficient for APBI than for conventional 3D-CRT and static-beam IMRT.
三维适形放射治疗（3D-CRT）、调强弧形放疗（IMRT）和容积调强弧形放疗（V-MAT）在加速部分乳腺照射（APBI）治疗中的效果。总体而言，16例T1/2N0期乳腺癌患者在RTOG 0413部分乳腺试验中接受了3D-CRT（多个非共面光子野）治疗。随后，使用静态机架IMRT和V-MAT技术对这些病例进行重新计划，以了解这三种技术之间的剂量学差异。在计划质量评估中使用了几个剂量学参数，包括剂量适形指数（CI）和正常组织覆盖的剂量体积直方图分析。进行了包括伽马分析在内的质量保证研究，以比较测量和计算的剂量分布。IMRT和V-MAT计划给出的靶区剂量分布比3D-CRT计划更适形（CI方面p<0.05）。使用V-MAT技术时，同侧乳腺接受5Gy和10Gy剂量的体积显著小于3D-CRT或IMRT（p<0.05）。V-MAT和IMRT的最大肺剂量以及接受10（V10）或20Gy（V20）剂量的同侧肺体积均显著更小（p<0.05）。在同侧肺低剂量分布方面，IMRT技术优于3D-CRT和V-MAT（V5和D5方面p<0.05）。V-MAT的总平均监测单位（MUs）（621.0±111.9）比3D-CRT（707.3±130.9）少12.2%，比IMRT（1161.4±315.6）少46.5%（p<0.05）。V-MAT计划的平均机器照射时间为1.5±0.2分钟，3D-CRT计划为7.0±1.6分钟，IMRT计划为11.5±1.9分钟，表明V-MAT的照射时间短得多。基于这项初步研究，与3D-CRT技术相比，V-MAT和IMRT技术在不增加同侧肺剂量的情况下提供了更好的剂量适形性。在监测单位和照射时间方面，V-MAT在APBI治疗中比传统3D-CRT和静态束IMRT效率显著更高。
