Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
Br J Radiol. 2010 Oct;83(994):874-81. doi: 10.1259/bjr/59469015. Epub 2010 Mar 11.
The aim of this study was to investigate if non-coplanar intensity-modulated radiation therapy (IMRT) in the post-mastectomy setting can reduce the dose to normal structures and improve target coverage. We compared this IMRT technique with a standard partial wide tangential (PWT) plan and a five-field (5F) photon-electron plan. 10 patients who underwent left-sided mastectomy were planned to 50.4 Gy using either (1) PWT to cover the internal mammary (IM) nodes and supraclavicular fields, (2) 5F comprising standard tangents, supraclavicular fields and an electron field for the IM nodes or (3) IMRT. The planning target volume (PTV) included the left chest wall, supraclavicular, axillary and IM lymph nodes. No beams were directed at the right lung, right breast or heart. Mean dose-volume histograms were constructed by combining the dose-volume histogram data from all 10 patients. The mean PTV to receive 95% of the dose (V95%) was improved with the IMRT plan to 94.2% from 91.4% (p = 0.04) with the PWT plan and from 87.7% (p = 0.012) with the 5F plan. The mean V110% of the PTV was improved to 3.6% for the IMRT plan from 16.8% (p = 0.038) for the PWT plan and from 51.8% (p = 0.001) for the 5F plan. The mean fraction volume receiving 30 Gy (v30Gy) of the heart was improved with the IMRT plan to 2.3% from 7.5% (p = 0.01) for the PWT plan and 4.9% (p = 0.02) for the 5F plan. In conclusion, non-coplanar IMRT results in improved coverage of the PTV and a lower heart dose when compared with a 5F or PWT plan.
本研究旨在探讨在乳腺癌根治术后采用非共面调强放疗（IMRT）是否能降低正常组织剂量并提高靶区覆盖。我们将这种调强放疗技术与标准部分宽切线野（PWT）计划和五野（5F）光子电子混合计划进行了比较。10 例接受左侧乳房切除术的患者分别采用以下三种方法进行 50.4Gy 的放疗：（1）PWT 覆盖内乳（IM）淋巴结和锁骨上野；（2）5F 包括标准切线野、锁骨上野和 IM 淋巴结电子野；（3）IMRT。计划靶区（PTV）包括左胸壁、锁骨上、腋窝和 IM 淋巴结。没有射束照射右侧肺、右侧乳房或心脏。通过将 10 例患者的剂量-体积直方图数据合并，构建了平均剂量-体积直方图。PTV 接受 95%剂量（V95%）的平均值，与 PWT 计划相比，IMRT 计划从 91.4%提高到 94.2%（p=0.04），与 5F 计划相比从 87.7%提高到 94.2%（p=0.012）。PTV 接受 110%剂量（V110%）的平均值，与 PWT 计划相比，IMRT 计划从 16.8%（p=0.038）降至 3.6%，与 5F 计划相比从 51.8%（p=0.001）降至 3.6%。心脏接受 30Gy（v30Gy）剂量的平均体积分数，与 PWT 计划相比，IMRT 计划从 7.5%（p=0.01）降至 2.3%，与 5F 计划相比从 4.9%（p=0.02）降至 2.3%。总之，与 5F 或 PWT 计划相比，非共面 IMRT 可提高 PTV 的覆盖范围并降低心脏剂量。
