Mary Bird Perkins Cancer Center, Baton Rouge, LA 70809, USA.
Br J Radiol. 2012 Mar;85(1011):231-6. doi: 10.1259/bjr/94843998. Epub 2011 Jun 28.
Volumetric-modulated arc therapy (VMAT) is becoming an increasingly utilised modality for treating a variety of anatomical sites. However, the efficacy of single-arc VMAT to treat prostate cancer suspicious for extraprostatic extension was heretofore unknown. In this work, we report our institutional experience with single-arc VMAT and fixed-beam intensity-modulated radiation therapy (IMRT) for prostate cancer patients treated for seminal vesicle and/or lymph node involvement.
Single-arc VMAT and 7- or 9-field IMRT treatment plans were compared for 10 prostate cancer patients treated for seminal vesicle involvement and/or lymph node involvement. All treatment plans were constructed using the Philips Pinnacle treatment planning system (v.9.0, Fitchburg, WI) and delivered on an Elekta Infinity radiotherapy accelerator (Crawley, UK). Resulting plans were compared using metrics that characterised dosimetry and delivery efficiency.
No statistically significant differences in target coverage, target homogeneity or normal tissue doses were noted between the plans (p>0.05). For prostate patients treated for seminal vesicle involvement, VMAT plans were delivered in 1.4±0.1 min (vs 9.5±2.4 min for fixed-beam IMRT) (p<0.01) and required approximately 20% fewer monitor units (p=0.01). For prostate patients treated for lymph node involvement, VMAT plans were delivered in 1.4±0.1 min (vs 11.7±1.3 min for fixed-beam IMRT) (p<0.01) and required approximately 45% fewer monitor units (p<0.01).
Single-arc VMAT plans were dosimetrically equivalent to fixed-beam IMRT plans with significantly improved delivery efficiency.
容积调强弧形治疗（VMAT）正成为治疗多种解剖部位的一种越来越常用的方法。然而，单弧 VMAT 治疗前列腺癌疑似外扩的疗效在此之前尚不清楚。在这项工作中，我们报告了我们机构在治疗因精囊和/或淋巴结受累而接受治疗的前列腺癌患者时使用单弧 VMAT 和固定束强度调制放射治疗（IMRT）的经验。
对 10 例因精囊和/或淋巴结受累而接受治疗的前列腺癌患者，比较了单弧 VMAT 和 7 野或 9 野 IMRT 治疗计划。所有治疗计划均使用飞利浦 Pinnacle 治疗计划系统（v.9.0，Fitchburg，WI）和 Elekta Infinity 放射治疗加速器（英国 Crawley）构建。使用剂量学和输送效率的指标来比较结果计划。
在靶区覆盖、靶区均匀性或正常组织剂量方面，计划之间没有统计学上的显著差异（p>0.05）。对于因精囊受累而接受治疗的前列腺癌患者，VMAT 计划的输送时间为 1.4±0.1 分钟（而固定束 IMRT 为 9.5±2.4 分钟）（p<0.01），并且需要大约 20%的较少的监测单位（p=0.01）。对于因淋巴结受累而接受治疗的前列腺癌患者，VMAT 计划的输送时间为 1.4±0.1 分钟（而固定束 IMRT 为 11.7±1.3 分钟）（p<0.01），并且需要大约 45%的较少的监测单位（p<0.01）。
单弧 VMAT 计划在剂量学上与固定束 IMRT 计划等效，但输送效率显著提高。
