Department of Radiation Oncology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada.
Int J Radiat Oncol Biol Phys. 2012 Mar 15;82(4):e657-62. doi: 10.1016/j.ijrobp.2011.09.006. Epub 2012 Jan 13.
To perform a comparison of two pelvic lymph node volume delineation strategies used in intensity-modulated radiotherapy (IMRT) for high risk prostate cancer and to determine the role of volumetric modulated arc therapy (VMAT).
Eighteen consecutive patients accrued to an ongoing clinical trial were identified according to either the nodal contouring strategy as described based on lymphotropic nanoparticle-enhanced magnetic resonance imaging technology (9 patients) or the current Radiation Therapy Oncology Group (RTOG) consensus guidelines (9 patients). Radiation consisted of 45 Gy to prostate, seminal vesicles, and lymph nodes, with a simultaneous integrated boost to the prostate alone, to a total dose of 67.5 Gy delivered in 25 fractions. Prospective acute genitourinary and gastrointestinal toxicities were compared at baseline, during radiotherapy, and 3 months after radiotherapy. Each patient was retrospectively replanned using the opposite method of nodal contouring, and plans were normalized for dosimetric comparison. VMAT plans were also generated according to the RTOG method for comparison.
RTOG plans resulted in a significantly lower rate of genitourinary frequency 3 months after treatment. The dosimetric comparison showed that the RTOG plans resulted in both favorable planning target volume (PTV) coverage and lower organs at risk (OARs) and integral (ID) doses. VMAT required two to three arcs to achieve adequate treatment plans, we did not observe consistent dosimetric benefits to either the PTV or the OARs, and a higher ID was observed. However, treatment times were significantly shorter with VMAT.
The RTOG guidelines for pelvic nodal volume delineation results in favorable dosimetry and acceptable acute toxicities for both the target and OARs. We are unable to conclude that VMAT provides a benefit compared with IMRT.
对两种用于高危前列腺癌调强放疗（IMRT）的盆腔淋巴结体积勾画策略进行比较，并确定容积旋转调强放疗（VMAT）的作用。
根据基于淋巴亲脂性纳米颗粒增强磁共振成像技术的淋巴结勾画策略（9 例）或当前放射治疗肿瘤学组（RTOG）共识指南（9 例），对连续纳入的 18 例患者进行了识别。患者接受 45Gy 的前列腺、精囊和淋巴结照射，同时对前列腺进行同步整合增敏照射，总剂量为 67.5Gy，分 25 次进行。在基线、放疗期间和放疗后 3 个月前瞻性比较急性泌尿生殖和胃肠道毒性。对每个患者采用相反的淋巴结勾画方法进行回顾性再计划，并对计划进行归一化比较。根据 RTOG 方法生成 VMAT 计划进行比较。
RTOG 计划在治疗后 3 个月后泌尿生殖频率明显降低。剂量学比较表明，RTOG 计划在规划靶区（PTV）覆盖和降低危及器官（OARs）和积分剂量（ID）方面均有优势。VMAT 需要 2 到 3 个弧才能实现足够的治疗计划，但我们没有观察到 PTV 或 OARs 的一致剂量学优势，并且观察到更高的 ID。然而，VMAT 的治疗时间明显缩短。
RTOG 指南用于盆腔淋巴结体积勾画，可获得靶区和 OARs 良好的剂量学和可接受的急性毒性。我们无法得出 VMAT 与 IMRT 相比具有优势的结论。
