Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
Radiother Oncol. 2021 May;158:1-6. doi: 10.1016/j.radonc.2021.01.039. Epub 2021 Feb 13.
To investigate the potential of an offline Adaptive Radiotherapy (ART) strategy, based on the interfractional vagina motion (IVM) measured using fiducial markers (FM) during an initial number of fractions, on the CTV to PTV margins in post-operative gynecological patients.
In 18 patients, treated post-operatively for gynecological tumors, the systematic residual IVM was quantified after simulating an offline ART procedure, utilizing the average IVM measured with FM for a varying initial numbers of fractions to find the optimal moment to adapt the treatment plan and a threshold for selecting patients for replanning. Clinical margins for a zero, 2 and 5 mm threshold based strategy were calculated to assess the possible margin reduction.
Applying an ART strategy based on the average IVM of the initial 5 fractions reduces the systematic IVM significantly (P < 0.025), allowing a reduction of the clinical margin of 3 mm (20%) in the CC direction and 2 mm (13%) in the AP direction. A 2 mm threshold for selecting patients for replanning shows no difference in the reduction of the clinical margin, but reduces the workload with 12%.
An ART strategy based on adapting on the average IVM during the initial 5 fractions of treatment provides an opportunity to reduce the CTV to PTV margins in postoperative gynecological tumors. To keep the workload in balance with the best achievable margin reduction, a threshold for selecting patients for plan adaptation is recommended.
研究基于初始部分分次治疗期间使用基准标记（FM）测量的阴道间离室运动（IVM）的离线自适应放疗（ART）策略，对术后妇科患者的CTV 至 PTV 边界的潜在影响。
在 18 例术后接受妇科肿瘤治疗的患者中，模拟离线 ART 程序后量化了系统残余 IVM，利用 FM 测量的平均 IVM 对初始分次数量进行了变化，以确定最佳调整治疗计划的时机和选择患者进行重新计划的阈值。计算了基于 0、2 和 5mm 阈值的策略的临床边界，以评估可能的边界减少。
应用基于前 5 个分次平均 IVM 的 ART 策略可显著降低系统 IVM（P<0.025），允许 CC 方向的临床边界减少 3mm（20%），AP 方向减少 2mm（13%）。选择 2mm 阈值进行患者重新计划的策略，对临床边界的减少没有差异，但可以减少 12%的工作量。
基于治疗初始 5 个分次期间平均 IVM 进行调整的 ART 策略，为降低术后妇科肿瘤的 CTV 至 PTV 边界提供了机会。为了在最佳的边界减少与平衡的工作量之间取得平衡，建议为计划适应选择患者的阈值。
