Simultaneous couch and gantry dynamic arc rotation (CG-Darc) in the treatment of breast cancer with accelerated partial breast irradiation (APBI): a feasibility study
Simultaneous couch and gantry dynamic arc rotation (CG-Darc) in the treatment of breast cancer with accelerated partial breast irradiation (APBI): a feasibility study
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DOI：
10.1120/jacmp.v14i1.4035
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发表时间：
2013-01-01
影响因子：
2.1
通讯作者：
Vlachaki, Maria T.
中科院分区：
文献类型：
--
作者：
Popescu, Carmen C.;Beckham, Wayne A.;Vlachaki, Maria T.
本研究的目的是比较CG-Darc与三维适形放射治疗（3D CRT）和调容弧治疗（RapidArc）在乳腺癌APBI治疗中的剂量学。使用两个切向治疗床弧与同时非共面机架弧相结合生成CG-Darc计划。动态治疗床弧由10个间隔的连续调强放射治疗场模拟。RapidArc计划使用带有回避扇区的单个部分弧，防止射束直接进入胸腔。在20例既往接受过3D CRT治疗的患者（A组）和另外15例未通过加拿大试验和NSABP B-39/RTOG 0413剂量限制的APBI患者（B组）中，将CG-Darc和RapidArc计划与3D CRT进行了比较。与3D CRT和RapidArc相比，CG-Darc的目标覆盖率上级（V95%：98.2% vs. 97.1%和95.7%）。对于外乳病变，与3D CRT相比，CG-Darc和RapidArc显著降低了同侧乳腺V50%，A组降低了8%，B组降低了15%（p < 0.05）。对于内部和中心病变，与3D CRT和RapidArc相比，CG-Darc导致同侧肺V10%显著降低（A组10.7% vs. 12.6%和20.7%，B组15.1% vs. 25.2%和27.3%）。在对侧乳房的剂量测定中观察到类似的优势，其中CG-Darc、3D CRT和RapidArc的最大剂量百分比分别为3.9%、6.3%和5.8%（A组）和4.3%、9.2%和6.3%（B组）（p < 0.05）。CG-Darc实现了上级靶覆盖，同时降低了正常组织剂量，即使在APBI剂量限制失败的患者中也是如此。因此，该技术有可能将APBI的使用扩展到目前不适合此类治疗的患者。需要修改RapidArc算法，以将治疗床和机架旋转与可变剂量率联系起来，因此，可以在临床实践中使用CG-Darc。
The purpose of this study was to compare the dosimetry of CG-Darc with three-dimensional conformal radiation therapy (3D CRT) and volumetric-modulated arc therapy (RapidArc) in the treatment of breast cancer with APBI. CG-Darc plans were generated using two tangential couch arcs combined with a simultaneous noncoplanar gantry arc. The dynamic couch arc was modeled by consecutive IMRT fields at 10 intervals. RapidArc plans used a single partial arc with an avoidance sector, preventing direct beam exit into the thorax. CG-Darc and RapidArc plans were compared with 3D CRT in 20 patients previously treated with 3D CRT (group A), and in 15 additional patients who failed the dosimetric constraints of the Canadian trial and of NSABP B-39/RTOG 0413 for APBI (group B). CG-Darc resulted in superior target coverage compared to 3D CRT and RapidArc (V95%: 98.2% vs. 97.1% and 95.7%). For outer breast lesions, CG-Darc and RapidArc significantly reduced the ipsilateral breast V50% by 8% in group A and 15% in group B (p < 0.05) as compared with 3D CRT. For inner and centrally located lesions, CG-Darc resulted in significant ipsilateral lung V10% reduction when compared to 3D CRT and RapidArc (10.7% vs. 12.6% and 20.7% for group A, and 15.1% vs. 25.2% and 27.3% for group B). Similar advantage was observed in the dosimetry of contralateral breast where the percent maximum dose for CG-Darc, 3D CRT, and RapidArc were 3.9%, 6.3%, and 5.8% for group A and 4.3%, 9.2%, and 6.3% for group B, respectively (p < 0.05). CG-Darc achieved superior target coverage while decreasing normal tissue dose even in patients failing APBI dose constraints. Consequently, this technique has the potential of expanding the use of APBI to patients currently ineligible for such treatment. Modification of the RapidArc algorithm will be necessary to link couch and gantry rotation with variable dose rate and, therefore, enable the use of CG-Darc in clinical practice.