A fast and robust constraint-based online re-optimization approach for automated online adaptive intensity modulated proton therapy in head and neck cancer

A fast and robust constraint-based online re-optimization approach for automated online adaptive intensity modulated proton therapy in head and neck cancer

Oud, Michelle (Erasmus MC; Holland Particle Therapy Centre)
Breedveld, Sebastiaan (Erasmus MC)
Rojo-Santiago, Jesús (Erasmus MC; Holland Particle Therapy Centre)
Giżyńska, Marta Krystyna (Holland Particle Therapy Centre)
Kroesen, Michiel (Erasmus MC)
Habraken, S.J.M. (Erasmus MC; Holland Particle Therapy Centre)
Perko, Z. (TU Delft RST/Reactor Physics and Nuclear Materials)
Heijmen, Ben (Erasmus MC)
Hoogeman, M.S. (TU Delft RST/Medical Physics & Technology; Erasmus MC; Holland Particle Therapy Centre)

2024

Objective. In head-and-neck cancer intensity modulated proton therapy, adaptive radiotherapy is currently restricted to offline re-planning, mitigating the effect of slow changes in patient anatomies. Daily online adaptations can potentially improve dosimetry. Here, a new, fully automated online re-optimization strategy is presented. In a retrospective study, this online re-optimization approach was compared to our trigger-based offline re-planning (offlineTB re-planning) schedule, including extensive robustness analyses. Approach. The online re-optimization method employs automated multi-criterial re-optimization, using robust optimization with 1 mm setup-robustness settings (in contrast to 3 mm for offlineTB re-planning). Hard planning constraints and spot addition are used to enforce adequate target coverage, avoid prohibitively large maximum doses and minimize organ-at-risk doses. For 67 repeat-CTs from 15 patients, fraction doses of the two strategies were compared for the CTVs and organs-at-risk. Per repeat-CT, 10.000 fractions with different setup and range robustness settings were simulated using polynomial chaos expansion for fast and accurate dose calculations. Main results. For 14/67 repeat-CTs, offlineTB re-planning resulted in <50% probability of D98% ≥ 95% of the prescribed dose (Dpres) in one or both CTVs, which never happened with online re-optimization. With offlineTB re-planning, eight repeat-CTs had zero probability of obtaining D98% ≥ 95%Dpres for CTV7000, while the minimum probability with online re-optimization was 81%. Risks of xerostomia and dysphagia grade ≥ II were reduced by 3.5 ± 1.7 and 3.9 ± 2.8 percentage point [mean ± SD] (p < 10−5 for both). In online re-optimization, adjustment of spot configuration followed by spot-intensity re-optimization took 3.4 min on average. Significance. The fast online re-optimization strategy always prevented substantial losses of target coverage caused by day-to-day anatomical variations, as opposed to the clinical trigger-based offline re-planning schedule. On top of this, online re-optimization could be performed with smaller setup robustness settings, contributing to improved organs-at-risk sparing.

intensity modulated proton therapy (IMPT)
daily online adaptive radiotherapy using dose restoration
head-and-neck cancer
inter-fraction anatomy variation
automated treatment planning

http://resolver.tudelft.nl/uuid:9af93419-2648-4a16-89d8-e34aa863e637

https://doi.org/10.1088/1361-6560/ad2a98

0031-9155

Physics in Medicine and Biology, 69 (7)

Institutional Repository

journal article

© 2024 Michelle Oud, Sebastiaan Breedveld, Jesús Rojo-Santiago, Marta Krystyna Giżyńska, Michiel Kroesen, S.J.M. Habraken, Z. Perko, Ben Heijmen, M.S. Hoogeman