Center for Proton Therapy, Paul Scherrer Institute, Villigen, Switzerland.
Int J Radiat Oncol Biol Phys. 2010 Mar 1;76(3):685-97. doi: 10.1016/j.ijrobp.2009.02.062. Epub 2009 Jul 15.
To study the potential reduction of dose to organs at risk (OARs) with intensity-modulated proton radiotherapy (IMPT) compared with intensity-modulated radiotherapy (IMRT) and three-dimensional conformal radiotherapy (3D-CRT) photon radiotherapy for left-sided breast cancer patients.
Comparative treatment-planning was performed using planning computed tomography scans of 20 left-sided breast cancer patients. For each patient, three increasingly complex locoregional volumes (planning target volumes [PTVs]) were defined: whole breast (WB) or chest wall (CW) = (PTV1), WB/CW plus medial-supraclavicular (MSC), lateral-supraclavicular (LSC), and level III axillary (AxIII) nodes = (PTV2) and WB/CW+MSC+LSC+AxIII plus internal mammary chain = (PTV3). For each patient, 3D-CRT, IMRT, and IMPT plans were optimized for PTV coverage. Dose to OARs was compared while maintaining target coverage.
All the techniques met the required PTV coverage except the 3D-CRT plans for PTV3-scenario. All 3D-CRT plans for PTV3 exceeded left-lung V20. IMPT vs. 3D-CRT: significant dose reductions were observed for all OARs using IMPT for all PTVs. IMPT vs. IMRT: For PTV2 and PTV3, low (V5) left lung and cardiac doses were reduced by a factor >2.5, and cardiac doses (V22.5) were by a factor of >20 lower with IMPT compared with IMRT.
When complex-target irradiation is needed, 3D-CRT often compromises the target coverage and increases the dose to OARs; IMRT can provide better results but will increase the integral dose. The benefit of IMPT is based on improved target coverage and reduction of low doses to OARs, potentially reducing the risk of late-toxicity. These results indicate a potential role of proton-radiotherapy for extended locoregional irradiation in left breast cancer.
研究与强度调制光子放射治疗（IMRT）和三维适形放射治疗（3D-CRT）相比，左侧乳腺癌患者使用调强质子放射治疗（IMPT）治疗时，对危及器官（OARs）剂量的潜在降低效果。
对 20 例左侧乳腺癌患者的计划计算机断层扫描进行了比较性治疗计划。对于每个患者，定义了三个逐渐复杂的局部区域体积（PTV）：全乳（WB）或胸壁（CW）=（PTV1）、WB/CW 加内上锁骨区（MSC）、外侧锁骨区（LSC）和 III 级腋窝（AxIII）淋巴结=（PTV2）以及 WB/CW+MSC+LSC+AxIII 加内乳链=（PTV3）。对于每个患者，都为 PTV 覆盖优化了 3D-CRT、IMRT 和 IMPT 计划。在保持靶区覆盖的同时，比较了 OAR 的剂量。
除 PTV3 方案的 3D-CRT 计划外，所有技术均满足所需的 PTV 覆盖范围。所有 PTV3 的 3D-CRT 计划均超过左肺 V20。与 3D-CRT 相比，IMPT：对于所有 PTV，与 3D-CRT 相比，使用 IMPT 可显著降低所有 OAR 的剂量。与 IMRT 相比，对于 PTV2 和 PTV3，左肺和心脏的低剂量（V5）降低了 2.5 倍以上，心脏剂量（V22.5）降低了 20 倍以上。
当需要复杂靶区照射时，3D-CRT 通常会影响靶区覆盖范围并增加 OAR 剂量；IMRT 可以提供更好的结果，但会增加积分剂量。IMPT 的优势在于改善靶区覆盖范围并降低 OAR 的低剂量，从而降低迟发性毒性的风险。这些结果表明质子放疗在左侧乳腺癌扩展局部区域照射中具有潜在作用。
