ESTRO 2024 - Abstract Book

S4405

Physics - Intra-fraction motion management and real-time adaptive radiotherapy

ESTRO 2024

3191

Digital Poster

First experience with oART: analysis of employed time during adaptive sessions

Naiara Fuentemilla-Urío 1 , Santiago Pellejero 1 , Victor De La Llana 1 , Mario Martín Veganzones 1 , Mikel Rico 2 , Marta Barrado 2 1 Hospital Universitario de Navarra, Radiofísica y PR, Pamplona, Spain. 2 Hospital Universitario de Navarra, Oncología Radioterapica, Pamplona, Spain

Purpose/Objective:

In March 2023, we began treating prostate patients with online adaptive RT (oART), with the Ethos system (Varian Medical Systems, Siemens, USA). Until October 2023, 29 intermediate and high risk prostate patients have been treated (a total of 410 sessions). One of the keys to the success of this type of treatment is the time spent in the online adaptation process. This work analyzes these times, separated into the different tasks into which the process is divided, from CBCT acquisition to treatment acceptance and QA.

Material/Methods:

The Ethos system incorporates a timer that displays every moment the time elapsed from CBCT reconstruction. The time between the reconstruction of the CBCT to the completion of each process has been noted: OAR contouring, CTV contouring, dosimetry acceptance and QA acceptance of the treatment plan, which is done with the Mobius3D system (Varian MS, Siemens, USA). During these months, different ways of performing the contouring have been tested (1st phase using artificial intelligence (AI) contouring for all organs, including prostate and vesicles, from which the corresponding CTVs are generated; 2nd phase using AI for OAR contouring and deformable registration for CTVs - rigid propagation of the prostate volume from pCT to daily CBCT -). During the first phase of work, the times of 106 fractions corresponding to 10 patients were analyzed and in the second phase 164 fractions (12 patients). The time spent for OAR contouring, CTV contouring, dosimetry acceptance and QA acceptance of the treatment plan was noted. The total time spent during the oART sessions is also presented on a time basis.

Results:

Graph 1 shows the total adaptation times, with a total time of 12.6 ± 4.2min in the 1st phase and 14.6 ± 3.0 min in the 2nd phase (the orange line marks the beginning of the 2nd phase).