Elith Craig A, Dempsey Shane E, Warren-Forward Helen M
British Columbia Cancer Agency, Fraser Valley Centre Surrey, BC, Canada ; School of Health Sciences, University of Newcastle Callaghan, NSW, Australia.
School of Health Sciences, University of Newcastle Callaghan, NSW, Australia.
J Med Radiat Sci. 2014 Jun;61(2):91-101. doi: 10.1002/jmrs.52. Epub 2014 May 20.
This study compared four different volumetric modulated arc therapy (VMAT) beam arrangements for the treatment of early-stage prostate cancer examining plan quality and the impact on a radiotherapy department's resources.
Twenty prostate cases were retrospectively planned using four VMAT beam arrangements (1) a partial arc (PA), (2) one arc (1A), (3) one arc plus a partial arc (1A + PA) and (4) two arcs (2A). The quality of the dose distributions generated were compared by examining the overall plan quality, the homogeneity and conformity to the planning target volume (PTV), the number of monitor units and the dose delivered to the organs at risk. Departmental resources were considered by recording the planning time and beam delivery time.
Each technique produced a plan of similar quality that was considered adequate for treatment; though some differences were noted. The 1A, 1A + PA and 2A plans demonstrated a better conformity to the PTV which correlated to improved sparing of the rectum in the 60-70 Gy range for the 1A + PA and 2A techniques. The time needed to generate the plans was different for each technique ranging from 13.1 min for 1A + PA to 17.8 min for 1A. The PA beam delivery time was fastest with a mean time of 0.9 min. Beam-on times then increased with an increase in the number of arcs up to an average of 2.2 min for the 2A technique.
Which VMAT technique is best suited for clinical implementation for the treatment of prostate cancer may be dictated by the individual patient and the availability of departmental resources.
本研究比较了四种不同的容积调强弧形放疗（VMAT）射束排列方式用于治疗早期前列腺癌的计划质量以及对放疗科室资源的影响。
对20例前列腺病例进行回顾性计划，采用四种VMAT射束排列方式：（1）部分弧形（PA），（2）单弧形（1A），（3）单弧形加部分弧形（1A + PA），（4）双弧形（2A）。通过检查总体计划质量、与计划靶区（PTV）的均匀性和适形性、监测单位数量以及危及器官的受量，比较所生成剂量分布的质量。通过记录计划时间和射束投照时间来考虑科室资源。
每种技术都产生了质量相似且被认为足以用于治疗的计划；不过也注意到了一些差异。1A、1A + PA和2A计划对PTV的适形性更好，这与1A + PA和2A技术在60 - 70 Gy范围内直肠受量的改善相关。每种技术生成计划所需的时间不同，从1A + PA的13.1分钟到1A的17.8分钟不等。PA射束投照时间最快，平均时间为0.9分钟。随着弧形数量的增加，射束开启时间增加，2A技术的平均时间达到2.2分钟。
哪种VMAT技术最适合临床用于治疗前列腺癌可能取决于个体患者情况和科室资源的可用性。
