Spare the Bowel, Don't Spoil the Target: Optimal Margin Assessment for Online Cone Beam Adaptive Radiation Therapy (OnC-ART) of the Cervix
Spare the Bowel, Don't Spoil the Target: Optimal Margin Assessment for Online Cone Beam Adaptive Radiation Therapy (OnC-ART) of the Cervix
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DOI：
10.1016/j.prro.2022.10.009
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发表时间：
2023-03-01
影响因子：
3.3
通讯作者：
Albuquerque, Kevin
中科院分区：
文献类型：
--
作者：
Yen, Allen;Choi, Byongsu;Albuquerque, Kevin
目的：局部晚期宫颈癌的标准治疗包括盆腔放化疗。调强放射治疗计划需要将子宫颈和子宫临床靶区 (CTV) 扩大 1.5 至 2 厘米，以适应运动。通过在线锥形束自适应放射治疗 (OnC-ART)，可以考虑分次间移动，这可能会导致 CTV 与计划靶区 (PTV) 的裕度较小。在这项研究中，我们试图确定 OnC-ART 充分覆盖的最佳 CTV-PTV 边界以及可能影响 CTV 覆盖的因素。方法和材料：纳入了 21 名接受根治性放化疗的宫颈癌患者的回顾性队列。 9 名接受非适应性放射治疗的患者在治疗前锥形束计算机断层扫描 (CBCT) 和治疗结束后的 CBCT 上绘制了宫颈轮廓。计算前后、横向和上下位移以及所有方向的平均位移。在 12 名接受 OnC-ART 治疗的患者组成的验证队列中确定并验证了 CTV 至 PTV 的扩展。结果：平均前后、横向和上下位移的标准差分别为 0.32 +/- 1.55 cm、0.12 +/- 2.31 cm 和 1.67 +/- 3.41 cm。预处理 CTV 周围均匀的 5 毫米扩张覆盖了最终治疗 CTV 的 98.85% +/- 1.23%。这种 5 毫米扩张应用于我们接受 OnC-ART 治疗的验证队列，覆盖了 98.39% +/- 3.0% 的最终治疗 CTV。 CBCT 之间的时间 >30 分钟和膀胱体积的变化与 CTV 覆盖范围显着相关。结论：根据我们的分析，5 毫米的 CTV 到 PTV 边缘足以涵盖 98% 的 CTV。显着降低的裕度可能会降低宫颈癌患者与放射相关的毒性，并改善患者报告的毒性结果。我们建议医生从 5 毫米边缘开始，并在日常适应期间通过图像引导评估足够的覆盖范围。(c) 2022 年美国放射肿瘤学会。由爱思唯尔公司出版。保留所有权利。
Purpose: The standard treatment for locally advanced cervical cancer involves pelvic chemoradiation. Intensity modulated radiation therapy planning requires expansion of the cervix and uterus clinical target volume (CTV) by 1.5 to 2 cm to account for motion. With online cone beam adaptive radiation therapy (OnC-ART), interfractional movement is accounted for, which can potentially lead to smaller CTV to planned target volume (PTV) margins. In this study, we attempted to determine the optimal CTV-to-PTV margin for adequate coverage with OnC-ART and factors that can affect CTV coverage.Methods and Materials: A retrospective cohort of 21 patients with cervical cancer treated with definitive chemoradiation was included. Nine patients treated with nonadaptive radiation had the uterocervix contoured on pretreatment cone beam computed tomog-raphy (CBCT) and end-treatment CBCTs. Anterior-posterior, lateral, and superior-inferior shifts and the average shift in all directions were calculated. A CTV-to-PTV expansion was determined and verified on a validation cohort of 12 patients treated with OnC-ART.Results: The average anterior-posterior, lateral, and superior-inferior shifts with standard deviation were 0.32 +/- 1.55 cm, 0.12 +/- 2.31 cm, and 1.67 +/- 3.41 cm, respectively. A uniform 5-mm expansion around the pretreatment CTV covered 98.85% +/- 1.23% of the end-treatment CTV. This 5-mm expansion was applied to our validation cohort treated with OnC-ART, and 98.39% +/- 3.0% of the end-treatment CTV was covered. Time between CBCTs >30 minutes and change in bladder volume were significantly correlated to CTV coverage.Conclusions: Based on our analysis, a CTV-to-PTV margin of 5 mm is adequate to encompass 98% of the CTV. A significantly reduced mar-gin could potentially decrease the toxicities associated with radiation for patients with cervical cancer and lead to improved patient reported toxic-ity outcomes. We recommend physicians begin with a 5-mm margin and assess adequate coverage with image guidance during daily adaptation.(c) 2022 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.