This study aimed to comprehensively present data on treatment optimization in linac-based SBRT for localized prostate cancer at a single institution. Moreover, the dosimetric quality and treatment efficiency of single-arc (SA) versus dual-arc (DA) VMAT planning and delivery approaches were compared. Re-optimization was performed on twenty low-to-intermediate-risk- (36.25 Gy in 5 fractions) and twenty high-risk (42.7 Gy in 7 fractions) prostate plans initially administered with the DA FFF-VMAT technique in 2021. An SA approach was adopted, incorporating new optimization parameters based on increased planning and clinical experience. Analysis included target coverage, organ-at-risk (OAR) sparing, treatment delivery time, and the pre-treatment verification’s gamma analysis-passing ratio. The SA optimization technique has consistently produced superior plans. Rectum and bladder mean doses were significantly reduced, and comparable target coverage and homogeneity were achieved in order to maintain a urethra protection strategy. The mean SA treatment delivery time was reduced by 22%; the mean monitor units increased due to higher plan complexity; and dose measurements demonstrated optimal agreement with calculations. The substantial reduction in treatment delivery time decreased the probability of prostate motion beyond the applied margins, suggesting potential decrease in treatment-related toxicity and improved target coverage in prostate SBRT. Further investigations are warranted to assess the long-term clinical outcomes.
本研究旨在全面呈现单一机构基于直线加速器的立体定向放射治疗（SBRT）在局限性前列腺癌治疗优化中的数据。同时，比较了单弧（SA）与双弧（DA）容积旋转调强放疗（VMAT）计划设计与实施方法的剂量学质量和治疗效率。研究对2021年采用双弧无均整滤束模式VMAT技术初始制定的20例低至中危（5次分割，总剂量36.25 Gy）和20例高危（7次分割，总剂量42.7 Gy）前列腺癌计划进行重新优化。优化采用单弧技术，并基于积累的计划设计和临床经验引入了新的优化参数。分析指标包括靶区覆盖度、危及器官保护、治疗实施时间以及治疗前验证的伽马分析通过率。单弧优化技术持续产生更优的治疗计划：在维持尿道保护策略的前提下，直肠和膀胱平均剂量显著降低，同时实现了可比的靶区覆盖度和剂量均匀性。单弧治疗平均实施时间减少22%；由于计划复杂度提高，平均监测单元数有所增加；剂量测量显示与计算结果高度吻合。治疗实施时间的大幅缩短降低了前列腺移动超出预设边界范围的概率，提示前列腺癌SBRT可能降低治疗相关毒性并改善靶区覆盖。未来需进一步研究评估其长期临床结局。
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