Alshamrani Amerah, Chuter Robert, Aznar Marianne, Hoskin Peter, Nelder Claire, Choudhury Ananya, Barraclough Lisa, Eccles Cynthia L
Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom; Department of Radiological Sciences, College of Health and Rehabilitation Sciences, Princess Nourah bint Abdulrahman University, Riyadh, Kingdom of Saudi Arabia.
Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom; Department of Clinical Oncology, Christie NHS Foundation Trust, Manchester, United Kingdom.
Acta Oncol. 2025 May 19;64:693-702. doi: 10.2340/1651-226X.2025.42898.
This study assessed the inter- and intra-fractional dosimetric impact of MR-Linac-based adaptive radiotherapy for cervical cancer (CC).
A retrospective analysis of five node-negative, locally advanced cervical cancer patients treated under the MOMENTUM study (NCT04075305) using adapt-to-shape (ATS) on an Elekta Unity MR-Linac. Assessing the dosimetric impact of daily online adaptations: (1) comparing dose between daily adapted (MR-adapted) and non-adapted (MR-guided) plans, by quantifying dose differences relative to reference plans (by 2 and 5%) and evaluating adaptation frequency; (2) performing intra-fraction dose evaluations. Dose metrics for targets and organs at risk (OARs) were evaluated following EMBRACE II guidelines.
MR-adapted plans improved target coverage or reduced OAR dose in 82-100% of fractions at a 2% dose deviation (and in 25-84% at a 5% deviation), compared to MR-guided plans. Dose reductions for OARs ranged from 2 to 8% for D0.1%, 4.77-16.70% for V4000cGy and 2.10-14.00% for V3000cGy. Intra-fraction analysis showed that the difference between daily planned and delivered doses in all target structures was not clinically significant, ranging from 0.08 to 2.20%, except two fractions that experienced higher deviations (5%) in ITV45. Treatment was well-tolerated, with no Grade 2 or 3 toxicities reported.
MR-guided plans required adaptation in 25-100% of the fractions when compared to MR-adapted plans. MR-adapted plans demonstrated enhanced target dose consistency and reduced OAR dose for all patients, highlighting the benefits of daily adaptation. Despite longer treatment times, dose accuracy was preserved. Toxicity results for MRgART in CC appear promising.
本研究评估了基于磁共振直线加速器（MR-Linac）的宫颈癌（CC）自适应放疗在分次间和分次内的剂量学影响。
对五项在MOMENTUM研究（NCT04075305）中接受治疗的淋巴结阴性、局部晚期宫颈癌患者进行回顾性分析，这些患者在Elekta Unity MR-Linac上采用适应形状（ATS）技术。评估每日在线自适应的剂量学影响：（1）通过量化相对于参考计划的剂量差异（2%和5%）并评估适应频率，比较每日自适应（MR-自适应）计划和非自适应（MR-引导）计划之间的剂量；（2）进行分次内剂量评估。根据EMBRACE II指南评估靶区和危及器官（OARs）的剂量指标。
与MR-引导计划相比，在2%剂量偏差时，MR-自适应计划在82%-100%的分次中改善了靶区覆盖或降低了OAR剂量（在5%偏差时为25%-84%）。OARs的剂量降低范围为：D0.1%降低2%-8%，V4000cGy降低4.77%-16.70%，V3000cGy降低2.10%-14.00%。分次内分析表明，所有靶区结构中每日计划剂量与实际 delivered 剂量之间的差异在临床上不显著，范围为0.08%-2.20%，除了两个在ITV45中出现较高偏差（5%）的分次。治疗耐受性良好，未报告2级或3级毒性反应。
与MR-自适应计划相比，MR-引导计划在25%-100%的分次中需要进行自适应。MR-自适应计划在所有患者中均表现出增强的靶区剂量一致性并降低了OAR剂量，突出了每日自适应的益处。尽管治疗时间延长，但剂量准确性得以保持。CC中MRgART的毒性结果似乎很有前景。
