Song Jun Yeong, Chie Eui Kyu, Kang Seong-Hee, Jeon Yeon-Jun, Ko Yoon-Ah, Kim Dong-Yun, Kang Hyun-Cheol
Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea.
Department of Radiation Oncology, Seoul National University College of Medicine, Seoul, Korea.
Radiat Oncol J. 2022 Dec;40(4):242-250. doi: 10.3857/roj.2022.00332. Epub 2022 Dec 26.
The safety of online contouring and planning for adaptive radiotherapy is unknown. This study aimed to evaluate the dosimetric difference of the organ-at-risk (OAR) according to the extent of contouring in stereotactic magnetic resonance image-guided adaptive RT (SMART) for pancreatic cancer.
We reviewed the treatment plan data used for SMART in patients with pancreatic cancer. For the online contouring and planning, OARs within 2 cm from the planning target volume (PTV) in the craniocaudal direction were re-controlled daily at the attending physician's discretion. The entire OARs were re-contoured retrospectively for data analysis. We termed the two contouring methods the Rough OAR and the Full OAR, respectively. The proportion of dose constraint violation and other dosimetric parameters was analyzed.
Nineteen patients with 94 fractions of SMART were included in the analysis. The dose constraint was violated in 10.6% and 43.6% of the fractions in Rough OAR and Full OAR methods, respectively (p = 0.075). Patients with a large tumor, a short distance from gross tumor volume (GTV) to OAR, and a tumor in the body or tail were associated with more occult dose constraint violations-large tumor (p = 0.027), short distance from GTV to OAR (p = 0.061), tumor in body or tail (p = 0.054). No dose constraint violation occurred outside 2 cm from the PTV.
More occult dose constraint violations can be found by the Full OAR method in patients with pancreatic cancer with some clinical factors in the online re-planning for SMART. Re-contouring all the OARs would be helpful to detect occult dose constraint violations in SMART planning. Since the dosimetric profile of SMART cannot be represented by a single fraction, patient selection for the Full OAR method should be weighted between the clinical usefulness and the time and workforce required.
在线轮廓勾画及自适应放疗计划的安全性尚不清楚。本研究旨在评估在立体定向磁共振图像引导的胰腺癌自适应放疗（SMART）中，根据危及器官（OAR）轮廓勾画范围的不同，OAR的剂量差异。
我们回顾了胰腺癌患者SMART治疗计划数据。对于在线轮廓勾画及计划，在头脚方向上距离计划靶体积（PTV）2 cm以内的OAR，由主治医师酌情每日重新勾画。对所有OAR进行回顾性重新勾画以进行数据分析。我们分别将这两种轮廓勾画方法称为粗略OAR和完整OAR。分析了剂量约束违反比例及其他剂量学参数。
19例患者共94次SMART治疗纳入分析。粗略OAR和完整OAR方法中分别有10.6%和43.6%的分次出现剂量约束违反（p = 0.075）。肿瘤大、大体肿瘤体积（GTV）到OAR距离短以及肿瘤位于体部或尾部的患者，更易出现隐匿性剂量约束违反——肿瘤大（p = 0.027）、GTV到OAR距离短（p = 0.061）、肿瘤位于体部或尾部（p = 0.054）。在距PTV 2 cm以外未出现剂量约束违反情况。
在胰腺癌患者SMART在线重新计划中，对于存在某些临床因素的患者，完整OAR方法能发现更多隐匿性剂量约束违反情况。重新勾画所有OAR有助于在SMART计划中检测隐匿性剂量约束违反。由于SMART的剂量分布不能由单次分次表示，完整OAR方法的患者选择应在临床实用性与所需时间和人力之间进行权衡。
