Washington University School of Medicine in St Louis, Department of Radiation Oncology, St Louis, Missouri.
Washington University School of Medicine in St Louis, Department of Radiation Oncology, St Louis, Missouri.
Int J Radiat Oncol Biol Phys. 2022 Dec 1;114(5):1022-1031. doi: 10.1016/j.ijrobp.2022.06.078. Epub 2022 Jun 26.
We conducted a prospective, in silico clinical imaging study (NCT04008537) to evaluate the feasibility of cone beam computed tomography-guided stereotactic adaptive radiation therapy (CT-STAR) for the treatment of abdominal oligometastases. We hypothesized that CT-STAR produces improved dosimetry compared with nonadapted CT-stereotactic body radiation therapy (SBRT).
Eight patients receiving stereotactic body radiation therapy for abdominal oligometastatic disease received 5 additional kV cone beam CTs on the ETHOS system. These additional cone beam CTs were used for imaging during an emulator treatment session. Initial plans were created based on their simulation (P) and emulated adaptive plans were based on anatomy-of-the-day. The prescription was 50 Gy out of 5 fractions. Organ-at-risk (OAR) constraints were prioritized over planning target volume coverage under a strict isotoxicity approach. The P was applied to the patient's anatomy-of-the-day and compared with the reoptimized adaptive plans using dose-volume histogram metrics, with selection of the superior plan. Feasibility was defined as completion of the adaptive workflow and compliance with strict OAR constraints in ≥80% of fractions. Fractions were performed under time pressures by a physician and physicist to mimic the adaptive process.
CT-STAR was feasible, with successful workflow completion in 38 out of 40 (95%) fractions. P application to daily anatomy created OAR constraint violations in 30 out of 40 (75%) fractions. There were 8 stomach, 18 duodenum, 16 small bowel, and 11 large bowel P OAR constraint violations. In contrast, OAR violations occurred in 2 out of 40 (5%) adaptive plans (both small bowel violations, both improved from the P). CT-STAR also improved gross tumor volume V100 and D95 coverage in 25 out of 40 (63%) and 20 out of 40 (50%) fractions, respectively. Zero out of 40 (0%) fractions were deemed nonfeasible due to poor image quality and/or inability to delineate structures. Adaptation time per fraction was a median of 22.59 minutes (10.97-47.23).
CT-STAR resolved OAR hard constraint violations and/or improved target coverage in silico compared with nonadapted CT-guided stereotactic body radiation therapy for the ablation of abdominal oligometastatic disease. Although limitations of this study include its small sample size and in silico design, the consistently high-quality cone beam CT images captured and comparable timing metrics to prior adaptive studies suggest that CT- STAR is a viable treatment paradigm for the ablation of abdominal oligometastatic disease. Clinical trials are in development to further evaluate CT-STAR in the clinic.
我们进行了一项前瞻性、计算机辅助的临床影像学研究（NCT04008537），以评估锥形束 CT 引导的立体定向自适应放疗（CT-STAR）治疗腹部寡转移的可行性。我们假设 CT-STAR 比非自适应 CT 立体定向体部放疗（SBRT）能产生更好的剂量学结果。
8 例接受腹部寡转移病灶立体定向放疗的患者在 ETHOS 系统上接受了 5 次额外的千伏锥形束 CT。这些额外的锥形束 CT 用于模拟器治疗过程中的成像。初始计划基于他们的模拟（P）制定，自适应计划基于当天的解剖结构。处方剂量为 50Gy，分 5 次。在严格的等毒理学方法下，器官危及器官（OAR）的限制优先于计划靶区的覆盖。P 被应用于患者当天的解剖结构，并使用剂量-体积直方图指标与重新优化的自适应计划进行比较，选择更好的计划。适应性工作流程的完成和 80%以上的分次治疗中严格遵守 OAR 限制被定义为可行性。在时间压力下，由医生和物理学家进行分次治疗，以模拟自适应过程。
CT-STAR 是可行的，40 次分次治疗中有 38 次（95%）成功完成了适应性工作流程。P 应用于每日解剖结构会导致 30 次（75%）分次治疗中的 OAR 限制违反，其中 8 次为胃、18 次为十二指肠、16 次为小肠和 11 次为大肠。相比之下，在 40 次自适应计划中仅出现 2 次（均为小肠限制违反，均比 P 有所改善）。CT-STAR 还改善了 25 次（63%）和 20 次（50%）分次治疗中肿瘤总体积（GTV）V100 和 D95 的覆盖范围。40 次治疗中无（0%）因图像质量差和/或无法勾画结构而导致的不可行性。每次分次治疗的自适应时间中位数为 22.59 分钟（10.97-47.23）。
与非自适应 CT 引导的立体定向体部放疗相比，CT-STAR 在计算机上解决了 OAR 硬限制违反问题，并改善了靶区覆盖范围，用于治疗腹部寡转移病灶。尽管该研究存在样本量小和计算机设计的局限性，但始终高质量的锥形束 CT 图像捕获和与之前自适应研究相当的时间指标表明，CT-STAR 是治疗腹部寡转移病灶的可行治疗方案。目前正在开展临床试验，以进一步评估 CT-STAR 在临床中的应用。
