Sarria Gustavo R, Schmitt Hanna, Jahnke Lennart, Bürgy Daniel, Wenz Frederik, Siebenlist Kerstin, Giordano Frank A, Jahnke Anika, Boda-Heggemann Judit
Department of Radiation Oncology, University Hostpital Bonn, University of Bonn, Bonn, Germany.
Department of Radiation Oncology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.
Adv Radiat Oncol. 2020 Oct 13;6(1):100593. doi: 10.1016/j.adro.2020.09.026. eCollection 2021 Jan-Feb.
This study aimed to investigate, in the setting of neoadjuvant gastric irradiation with integrated boost, whether cone beam computed tomography (CBCT)-based adaptive radiation therapy compared with a defined-filling protocol would be beneficial in terms of feasibility and achieving daily reproducible dose volume indexes of the planning target volume (PTV) and organs at risk (OARs) and workflow.
Planning computed tomography (PCT) and 25 CBCT scans of a previously treated patient were used, and neoadjuvant therapy of gastric carcinoma was simulated offline. PTVs and OARs were defined per the TOPGEAR protocol (PTV: 45 Gy/1.8 Gy), and an integrated boost (gross tumor volume [GTV]: 50.4 Gy/2.016 Gy) was added. The patient followed a filling regimen consisting of 12-hour fasting followed by 200 mL of water intake (2 glasses of water) immediately before irradiation. OARs and PTVs were newly contoured on each CBCT. Nonrigid registration of PCT and CBCT scans was performed. Nonadapted plans were recalculated on each CBCT (R-CBCT). Furthermore, an adapted plan was created for the new anatomy (A-CBCT). Dose parameters and comparison of R-CBCT and A-CBCT for the kidneys, liver, and heart were analyzed using a paired test.
A total of 200 plans for R-CBCT and A-CBCT were obtained. Mean gastric volumes were 277.32 cm (±54.40 cm) in CBCT scans and 519.2 cm in PCT. Mean doses to the PTV did not differ meaningfully within the CBCT scans, with an average of 1.54%. The D improved in GTV coverage by 5.26% compared with the R-CBCT plan. Mean heart, liver, and right kidney doses were reduced with the A-CBCT plan by 35.74%, 10.71% and 29.47%, respectively. The R- and A-CBCT comparison for GTV and OARs was significantly different in all cases ( < .0001).
Adaptive radiation therapy through deformable registration represents an important tool in neoadjuvant gastric irradiation, encompassing daily variability and organ motion, compared with the defined-filling protocol while improving OAR sparing.
本研究旨在探讨在新辅助胃照射联合增量照射的情况下，基于锥形束计算机断层扫描（CBCT）的自适应放射治疗与固定填充方案相比，在可行性、实现计划靶区（PTV）和危及器官（OARs）每日可重复的剂量体积指数以及工作流程方面是否有益。
使用一名先前治疗患者的计划计算机断层扫描（PCT）和25次CBCT扫描，离线模拟胃癌的新辅助治疗。根据TOPGEAR方案定义PTV和OARs（PTV：45 Gy/1.8 Gy），并添加联合增量照射（大体肿瘤体积[GTV]：50.4 Gy/2.016 Gy）。患者遵循一种填充方案，即照射前禁食12小时，然后立即摄入200 mL水（2杯水）。在每次CBCT上重新勾勒OARs和PTV。对PCT和CBCT扫描进行非刚性配准。在每次CBCT（R-CBCT）上重新计算非适应性计划。此外，针对新的解剖结构创建适应性计划（A-CBCT）。使用配对t检验分析R-CBCT和A-CBCT对肾脏、肝脏和心脏的剂量参数及比较结果。
共获得200个R-CBCT和A-CBCT计划。CBCT扫描中胃的平均体积为277.32 cm³（±54.40 cm³），PCT中为519.2 cm³。在CBCT扫描内，PTV的平均剂量差异无统计学意义，平均差异为1.54%。与R-CBCT计划相比，A-CBCT计划使GTV的剂量覆盖提高了5.26%。A-CBCT计划使心脏、肝脏和右肾的平均剂量分别降低了35.74%、10.71%和29.47%。在所有情况下，GTV和OARs的R-CBCT与A-CBCT比较均有显著差异（P <.0001）。
与固定填充方案相比，通过可变形配准的自适应放射治疗是新辅助胃照射中的一项重要工具，可涵盖每日的变异性和器官运动，同时提高对OARs的保护。
