Department of Radiation Oncology, VU University Medical Center, Amsterdam, The Netherlands.
Radiother Oncol. 2010 Feb;94(2):224-8. doi: 10.1016/j.radonc.2009.12.027. Epub 2010 Feb 1.
Outcomes for selected patients with spinal metastases may be improved by dose escalation using stereotactic body radiation therapy (SBRT). As target geometry is complex, we compared SBRT plans using volumetric modulated arc radiotherapy (RapidArc, RA) and conventional intensity-modulated radiotherapy (IMRT).
RA and IMRT plans to deliver a fraction of 16 Gy to at least 90% of planning target volume (PTV) were compared for PTV coverage, normal organ sparing and estimated delivery times. Group 1 consisted of PTVs to only vertebral body (n=3), while group 2 had PTVs encompassing the entire vertebra (n=4). Finally, RA delivery parameters in four patients were assessed.
Both techniques delivered 16 Gy to a mean of 95% and 85% of the PTV in groups 1 and 2, respectively. Spinal cord sparing was comparable; mean V(10-partial cord) for RA and IMRT in group 1 was 3.6%, and was 9.4% versus 11.5%, respectively, in group 2. Estimated mean treatment times for RA with 2-3 arcs and IMRT were comparable. Clinical RA beam-on times ranged from 11 to 15.4 min.
Both RA and conventional IMRT plans deliver high quality vertebral SBRT, but plan quality was poorer when the PTV consisted of the entire vertebra.
使用立体定向体部放射治疗（SBRT）进行剂量递增，可能会改善某些脊柱转移患者的预后。由于靶区几何形状复杂，我们比较了使用容积调强弧形放射治疗（RapidArc，RA）和常规调强放射治疗（IMRT）的 SBRT 计划。
比较了两组计划，一组是仅用于椎体（n=3）的计划（PTV），另一组是包含整个椎体的计划（n=4）。比较了两组计划的 PTV 覆盖、正常器官保护和预计治疗时间。RA 和 IMRT 计划分别将 16 Gy 的剂量递送至 PTV 至少 90%的区域。
两种技术分别将 16 Gy 的剂量递送至 PTV 的平均 95%和 85%，在两组中分别为 95%和 85%。脊髓保护效果相当；在第一组中，RA 和 IMRT 的平均 V（10 部分脊髓）分别为 3.6%和 9.4%和 11.5%。RA 与 2-3 个弧的 IMRT 治疗的估计平均治疗时间相当。RA 的临床射线开启时间为 11 至 15.4 分钟。
RA 和常规 IMRT 计划均可提供高质量的椎体 SBRT，但当 PTV 包含整个椎体时，计划质量较差。
