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

Phys Med Biol. 2024 Feb 19. doi: 10.1088/1361-6560/ad2a98. Online ahead of print.ABSTRACTObjective - In head-and-neck cancer intensity modulated proton therapy (IMPT), 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.&#xD;&#xD;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. &#xD;&#xD;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...
Source: Physics in Medicine and Biology - Category: Physics Authors: Source Type: research