Dohopolski Michael, Visak Justin, Choi Byongsu, Meng Boyu, Parsons David, Zhong Xinran, Inam Enobong, Avkshtol Vladimir, Moon Dominic, Sher David, Lin Mu-Han
Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX, USA.
Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX, USA; Department of Radiation Oncology, Yonsei Cancer Center, Seoul, Republic of Korea; Medical Physics and Biomedical Engineering Lab, Yonsei University College of Medicine, Seoul, Republic of Korea.
Radiother Oncol. 2024 Aug;197:110178. doi: 10.1016/j.radonc.2024.110178. Epub 2024 Mar 6.
We explore the potential dosimetric benefits of reducing treatment volumes through daily adaptive radiation therapy for head and neck cancer (HNC) patients using the Ethos system/Intelligent Optimizer Engine (IOE). We hypothesize reducing treatment volumes afforded by daily adaption will significantly reduce the dose to adjacent organs at risk. We also explore the capability of the Ethos IOE to accommodate this highly conformal approach in HNC radiation therapy.
Ten HNC patients from a phase II trial were chosen, and their cone-beam CT (CBCT) scans were uploaded to the adaptive RT (ART) emulator. A new initial reference plan was generated using both a 1 mm and 5 mm planning target volume (PTV) expansion. Daily adaptive ART plans (1 mm) were simulated from the clinical CBCT taken every fifth fraction. Additionally, using physician-modified ART contours the larger 5 mm plan was recalculated on this recontoured on daily anatomy. Changes in target and OAR contours were measured using Dice coefficients as a surrogate of clinician effort. PTV coverage and organ-at-risk (OAR) doses were statistically compared, and the robustness of each ART plan was evaluated at fractions 5 and 35 to observe if OAR doses were within 3 Gy of pre-plan.
This study involved six patients with oropharynx and four with larynx cancer, totaling 70 adaptive fractions. The primary and nodal gross tumor volumes (GTV) required the most adjustments, with median Dice scores of 0.88 (range: 0.80-0.93) and 0.83 (range: 0.66-0.91), respectively. For the 5th and 35th fraction plans, 80 % of structures met robustness criteria (quartile 1-3: 67-100 % and 70-90 %). Adaptive planning improved median PTV V100% coverage for doses of 70 Gy (96 % vs. 95.6 %), 66.5 Gy (98.5 % vs. 76.5 %), and 63 Gy (98.9 % vs. 74.9 %) (p < 0.03). Implementing ART with total volume reduction yielded median dose reductions of 7-12 Gy to key organs-at-risk (OARs) like submandibular glands, parotids, oral cavity, and constrictors (p < 0.05).
The IOE enables feasible daily ART treatments with reduced margins while enhancing target coverage and reducing OAR doses for HNC patients. A phase II trial recently finished accrual and forthcoming analysis will determine if these dosimetric improvements correlate with improved patient-reported outcomes.
我们探讨使用Ethos系统/智能优化器引擎（IOE），通过对头颈部癌（HNC）患者进行每日自适应放射治疗来减少治疗体积的潜在剂量学益处。我们假设每日自适应所带来的治疗体积减少将显著降低对相邻危及器官的剂量。我们还探讨了Ethos IOE在HNC放射治疗中采用这种高度适形方法的能力。
从一项II期试验中选取10例HNC患者，将他们的锥束CT（CBCT）扫描上传至自适应放疗（ART）模拟器。使用1毫米和5毫米的计划靶区（PTV）扩展生成新的初始参考计划。从每五分次采集的临床CBCT模拟每日自适应ART计划（1毫米）。此外，使用医生修改后的ART轮廓，在每日解剖结构上重新勾勒的轮廓上重新计算较大的5毫米计划。使用Dice系数作为临床医生工作量的替代指标来测量靶区和危及器官（OAR）轮廓的变化。对PTV覆盖情况和危及器官（OAR）剂量进行统计学比较，并在第5分次和第35分次评估每个ART计划的稳健性，以观察OAR剂量是否在计划前剂量的3 Gy范围内。
本研究纳入6例口咽癌患者和4例喉癌患者，共70个自适应分次。原发灶和淋巴结大体肿瘤体积（GTV）需要最多的调整，Dice评分中位数分别为0.88（范围：0.80 - 0.93）和0.83（范围：0.66 - 0.91）。对于第5分次和第35分次计划，80%的结构符合稳健性标准（四分位数1 - 3：67 - 100%和70 - 90%）。自适应计划改善了70 Gy剂量时PTV V100%的覆盖情况（96%对95.6%）、66.5 Gy剂量时（98.5%对76.5%）和63 Gy剂量时（98.9%对74.9%）（p < 0.03）。实施总体积减少的ART使下颌下腺、腮腺、口腔和咽缩肌等关键危及器官（OAR）的剂量中位数降低了7 - 12 Gy（p < 0.05）。
IOE能够实现可行的每日ART治疗，减少边界，同时提高靶区覆盖并降低HNC患者的OAR剂量。一项II期试验最近完成入组，即将进行的分析将确定这些剂量学改善是否与患者报告的结局改善相关。
