Lis Michelle, Newhauser Wayne, Donetti Marco, Wolf Moritz, Steinsberger Timo, Paz Athena, Graeff Christian
Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana, United States of America.
Biophysics Department, GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany.
Phys Med Biol. 2021 Nov 23;66(23). doi: 10.1088/1361-6560/ac36e7.
. The purpose of this study was to perform preliminary pre-clinical tests to compare the dosimetric quality of two approaches to treating moving tumors with ion beams: synchronously delivering the beam with the motion of a moving planning target volume (PTV) using the recently developed multi-phase 4D dose delivery (MP4D) approach, and asynchronously delivering the ion beam to a motion-encompassing internal tumor volume (ITV) combined with rescanning.. We created 4D optimized treatment plans with proton and carbon ion beams for two patients who had previously received treatment for non-small cell lung cancer. For each patient, we created several treatment plans, using approaches with and without motion mitigation: MP4D, ITV with rescanning, static deliveries to a stationary PTV, and deliveries to a moving tumor without motion compensation. Two sets of plans were optimized with margins or robust uncertainty scenarios. Each treatment plan was delivered using a recently-developed motion-synchronized dose delivery system (M-DDS); dose distributions in water were compared to measurements using gamma index analysis to confirm the accuracy of the calculations. Reconstructed dose distributions on the patient CT were analyzed to assess the dosimetric quality of the deliveries (conformity, uniformity, tumor coverage, and extent of hotspots).. Gamma index analysis pass rates confirmed the accuracy of dose calculations. Dose coverage was >95% for all static and MP4D treatments. The best conformity and the lowest lung doses were achieved with MP4D deliveries. Robust optimization led to higher lung doses compared to conventional optimization for ITV deliveries, but not for MP4D deliveries.. We compared dosimetric quality for two approaches to treating moving tumors with ion beams. Our findings suggest that the MP4D approach, using an M-DDS, provides conformal motion mitigation, with full target coverage and lower OAR doses.
本研究的目的是进行初步的临床前测试，以比较两种离子束治疗移动肿瘤方法的剂量学质量：使用最近开发的多阶段4D剂量递送（MP4D）方法，使束流与移动的计划靶体积（PTV）的运动同步递送；以及将离子束异步递送至包含运动的内部肿瘤体积（ITV）并结合重新扫描。我们为两名先前接受过非小细胞肺癌治疗的患者创建了质子和碳离子束的4D优化治疗计划。对于每位患者，我们使用有无运动缓解的方法创建了多个治疗计划：MP4D、带重新扫描的ITV、向固定PTV的静态递送以及向无运动补偿的移动肿瘤的递送。两组计划在有边缘或稳健不确定性情况下进行了优化。每个治疗计划都使用最近开发的运动同步剂量递送系统（M-DDS）进行递送；将水中的剂量分布与使用伽马指数分析的测量结果进行比较，以确认计算的准确性。分析患者CT上重建的剂量分布，以评估递送的剂量学质量（适形性、均匀性、肿瘤覆盖范围和热点范围）。伽马指数分析通过率证实了剂量计算的准确性。所有静态和MP4D治疗的剂量覆盖率均>95%。MP4D递送实现了最佳的适形性和最低的肺部剂量。与ITV递送的传统优化相比，稳健优化导致肺部剂量更高，但MP4D递送并非如此。我们比较了两种离子束治疗移动肿瘤方法的剂量学质量。我们的研究结果表明，使用M-DDS的MP4D方法提供了适形的运动缓解，具有完全的靶区覆盖和更低的危及器官剂量。
