A roadmap for implementation of kV‐CBCT online adaptive radiation therapy and initial first year experiences

Abstract

Purpose: Online Adaptive Radiation Therapy (oART) follows a different treatment paradigm than conventional radiotherapy, and because of this, the resources, implementation, and workflows needed are unique. The purpose of this report is to outline our institution's experience establishing, organizing, and implementing an oART program using the Ethos therapy system. Methods: We include resources used, operational models utilized, program creation timelines, and our institutional experiences with the implementation and operation of an oART program. Additionally, we provide a detailed summary of our first year's clinical experience where we delivered over 1000 daily adaptive fractions. For all treatments, the different stages of online adaption, primary patient set-up, initial kV-CBCT acquisition, contouring review and edit of influencer structures, target review and edits, plan evaluation and selection, Mobius3D 2nd check and adaptive QA, 2nd kV-CBCT for positional verification, treatment delivery, and patient leaving the room, were analyzed. Results: We retrospectively analyzed data from 97 patients treated from August 2021-August 2022. One thousand six hundred seventy seven individual fractions were treated and analyzed, 632(38%) were non-adaptive and 1045(62%) were adaptive. Seventy four of the 97 patients (76%) were treated with standard fractionation and 23 (24%) received stereotactic treatments. For the adaptive treatments, the generated adaptive plan was selected in 92% of treatments. On average(±std),adaptive sessions took 34.52 ± 11.42 min from start to finish.The entire adaptive process (from start of contour generation to verification CBCT), performed by the physicist (and physician on select days),was 19.84 ± 8.21 min. Conclusion:We present our institution's experience commissioning an oART program using the Ethos therapy system. It took us 12 months from project inception to the treatment of our first patient and 12 months to treat 1000 adaptive fractions. Retrospective analysis of delivered fractions showed that the average overall treatment time was approximately 35 min and the average time for the adaptive component of treatment was approximately 20 min.

Physicists should perform reference planning for CBCT guided online adaptive radiotherapy

“…Intent reviews could be implemented in the planning workflow to ensure adequate preparation prior to plan optimization within the IOE. 8 We agree that the planning techniques and optimization tools utilized within the IOE differ significantly from those in traditional TPS. However, our perspective maintains that the duty to impart knowledge and expertise to dosimetrists lies with the medical physicist, rather than assuming the role of primary planners.…”

Evaluation and correlation of patient movement during online adaptive radiotherapy with CBCT and a surface imaging system

“…Online adaptive therapy corrects for daily variations in patient set-up and anatomy by generating a new radiotherapy treatment plan using daily imaging to update structure contours. [1][2][3][4][5][6][7] Patients are kept in the treatment position for the entire adaptive session, which typically lasts between 20−45 min, leading to an increased likelihood of patient motion. 7 Typically, radiographic imaging is repeated prior to treatment to verify the integrity of the patient setup and acceptability of anatomical changes (e.g.…”

“…[1][2][3][4][5][6][7] Patients are kept in the treatment position for the entire adaptive session, which typically lasts between 20−45 min, leading to an increased likelihood of patient motion. 7 Typically, radiographic imaging is repeated prior to treatment to verify the integrity of the patient setup and acceptability of anatomical changes (e.g. bladder filling).…”

ART2Dose: A comprehensive dose verification platform for online adaptive radiotherapy

“…2,4 It can provide secondary dose check within approximately 5 min for adaptive plans on average. 5 For MR-based ART systems, such as the 0.35-T ViewRay MRIdian (ViewRay Inc., Oakwood, USA) and 1.5-T Elekta Unity (Elekta AB, Stockholm, Sweden), the secondary dose calculation requires additional magnetic field modeling. The MRIdian features a vendorprovided online adaptive QA tool integrated into the treatment console, enabling secondary dose calculations for new adaptive treatment plans and automatic generation of comprehensive reports including plan comparisons, 3D gamma analysis, contour/dose statistics, and per-beam fluence comparisons.…”

“…Mobius3D has been investigated as a secondary dose check system for Ethos and other treatment planning systems (TPS) 2,4 . It can provide secondary dose check within approximately 5 min for adaptive plans on average 5 …”