Byrne Mikel, Ray Xenia, Kisling Kelly, Archibald-Heeren Ben, Finnegan Robert, Luo Suhuai, Aland Trent, Greer Peter
Icon Group, South Brisbane, QLD, Australia.
School of Information and Physical Sciences, University of Newcastle, Newcastle, NSW, Australia.
J Appl Clin Med Phys. 2025 Jul;26(7):e70160. doi: 10.1002/acm2.70160.
Accurate dose accumulation is essential for understanding the delivered dose in online adaptive radiotherapy (OART). The aim of this study is to quantify the dose accumulation accuracy and clinical significance of dose accumulation errors in pelvis treatments using the Ethos v1.1 and v2.0 systems.
Three pelvic CTs had anatomically realistic deformation vector fields (DVF) applied to create new modified images. These modified images were then used as treatment images in simulated OART treatment sessions, and the dose was accumulated by the Ethos system (D(fx)). The inverse of the applied (true) DVF was also used to accumulate the delivered dose (D(fx)). The maximum applied DVF magnitude was compared to the maximum DVF magnitude calculated by the Ethos v1.1 and v2.0 systems. A 3D gamma analysis was performed between D(fx) and D(fx), and the clinical goals for each scenario were compared.
Large discrepancies in deformable registration magnitude were noted between the applied DVF and the Ethos DVF from both Ethos versions. All Ethos v1.1 results had 90% of points passing a 3%/2 mm gamma analysis, whilst Ethos v2.0 results did not reach this benchmark in all of the simulated scenarios. Results were particularly poor for the v2.0 prostate case. Inaccuracies in the dose accumulation process caused 6% of goals to change sufficiently such that the goal was reported as met or exceeded when it was not.
The Ethos v1.1 dose accumulation system has been found to perform acceptably for the pelvic CTs tested in this study. For the Ethos v2.0 system substantial discrepancies in the dose accumulation were noted.
准确的剂量累积对于理解在线自适应放射治疗（OART）中所给予的剂量至关重要。本研究的目的是使用Ethos v1.1和v2.0系统量化盆腔治疗中剂量累积的准确性以及剂量累积误差的临床意义。
对三个盆腔CT应用解剖学上逼真的变形矢量场（DVF）以创建新的修改图像。然后将这些修改后的图像用作模拟OART治疗过程中的治疗图像，并由Ethos系统累积剂量（D(fx)）。所应用的（真实的）DVF的逆也用于累积所给予的剂量（D(fx)）。将所应用的最大DVF幅度与Ethos v1.1和v2.0系统计算出的最大DVF幅度进行比较。在D(fx)和D(fx)之间进行三维伽马分析，并比较每种情况的临床目标。
在所应用的DVF与两个Ethos版本的Ethos DVF之间，在可变形配准幅度上存在较大差异。所有Ethos v1.1的结果有90%的点通过3%/2毫米伽马分析，而Ethos v2.0的结果在所有模拟情况下均未达到该基准。v2.0前列腺病例的结果尤其差。剂量累积过程中的不准确导致6%的目标发生足够大的变化，以至于在目标未达成时却报告为已达成或超过。
已发现Ethos v1.1剂量累积系统对于本研究中测试的盆腔CT表现尚可。对于Ethos v2.
