Nichols G, Fontenot J, Sanders M, Matthews K, Gibbons J
Louisiana State University, Baton Rouge, LA.
Mary Bird Perkins Cancer Center, Baton Rouge, LA.
Med Phys. 2012 Jun;39(6Part19):3841. doi: 10.1118/1.4735677.
To investigate the feasibility of volumetric modulated arc therapy (VMAT) for post-mastectomy radiotherapy (PMRT) and to compare dual- arc VMAT treatment plans to helical tomotherapy (HT) plans on the basis of dosimetric quality, radiobiological calculations and delivery efficiency.
Dual-arc VMAT and HT treatment plans were created for fifteen patients previously treated at our clinic. Planning target volumes (PTV) included the chest wall (CW) and regional lymph nodes. The following metrics were used to compare treatment plans for each patient: dose homogeneity index (DHI) and conformity index (CI); coverage of the PTV; dose to organs at risk (OAR); tumor control probability (TCP), normal tissue complication probability (NTCP) and secondary cancer complication probability (SCCP); and treatment delivery time. Differences between treatment plans were tested for significance using the paired Student's t-test.
Both modalities produced clinically acceptable PMRT plans. VMAT plans showed better CI (p < 0.01), and better OAR sparing at low doses than HT plans. For example, VMAT plans showed a 26% (p < 0.01) and 9% (p < 0.01) decrease in V5Gy in the lungs and heart respectively. On the other hand, HT plans showed better DHI (p < 0.01) and PTV coverage (p < 0.01). HT plans also showed slightly better OAR sparing at higher doses, including 8% (p < 0.01) and 9% (p < 0.01) lower maximum doses to the lungs and heart, respectively. Both modalities achieved nearly 100% tumor control and approximately 1% NTCP in the lungs and heart, with VMAT showing lower SCCP (p < 0.01). VMAT plans also required 66.2% less time to deliver.
Both VMAT and HT are suitable treatment options for PMRT. Our study showed that VMAT"'in addition to being significantly faster'"achieved better CI and low dose OAR sparing while HT achieved better DHI. This work was supported in part by a research support from Elekta, Ltd. However, Elekta, Ltd., did not participate in the study design; in the collection, analysis, and interpretation of data; in the writing of the manuscript; or in the decision to submit.
探讨容积调强弧形放疗（VMAT）用于乳房切除术后放疗（PMRT）的可行性，并基于剂量学质量、放射生物学计算和交付效率，将双弧VMAT治疗计划与螺旋断层放疗（HT）计划进行比较。
为我院先前治疗过的15例患者制定双弧VMAT和HT治疗计划。计划靶区（PTV）包括胸壁（CW）和区域淋巴结。使用以下指标比较每位患者的治疗计划：剂量均匀性指数（DHI）和适形指数（CI）；PTV的覆盖情况；危及器官（OAR）的剂量；肿瘤控制概率（TCP）、正常组织并发症概率（NTCP）和继发癌并发症概率（SCCP）；以及治疗交付时间。使用配对学生t检验检验治疗计划之间的差异是否具有显著性。
两种方式均产生了临床可接受的PMRT计划。VMAT计划显示出更好的CI（p < 0.01），并且在低剂量时比HT计划对OAR的保护更好。例如，VMAT计划显示肺部和心脏的V5Gy分别降低了26%（p < 0.01）和9%（p < 0.01）。另一方面，HT计划显示出更好的DHI（p < 0.01）和PTV覆盖情况（p < 0.01）。HT计划在较高剂量时对OAR的保护也略好，包括肺部和心脏的最大剂量分别降低了8%（p < 0.01）和9%（p < 0.01）。两种方式均实现了近100%的肿瘤控制，肺部和心脏的NTCP约为1%，VMAT的SCCP较低（p < 0.01）。VMAT计划的交付时间也减少了66.2%。
VMAT和HT都是PMRT合适的治疗选择。我们的研究表明，VMAT“除了显著更快之外”，还实现了更好的CI和低剂量OAR保护，而HT实现了更好的DHI。本研究部分得到了医科达有限公司的研究支持。然而，医科达有限公司未参与研究设计；未参与数据的收集、分析和解释；未参与稿件的撰写；也未参与提交决定。
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