Dosimetric assessment of online adaptive radiotherapy in the treatment of prostate cancer on the ethos accelerator

Introduction. Online adaptive radiotherapy is a radiotherapy technique that adjusts the dose distribution to the current dimensions, shapes, and positions of the treated volume, as well as critical organs, prior to each treatment session. The dose distribution is calculated based on the real-time contours and positions of the target volumes and critical organ structures. An adapted dose distribution is then generated according to the therapeutic goals defined during the treatment planning phase. The aim of this study was to evaluate the fulfillment of therapeutic goals in non-adaptive and online adaptive plans. Material and methods. The analysis included 42 consecutively treated patients with prostate cancer using the stereotactic body radiation therapy (SBRT) technique on the Ethos accelerator. The statistical significance of differences between the plans was evaluated using the Wilcoxon, Friedman McNemar’s test, with a significance level of p = 0.05. Results and conclusions. The comparisons showed that 95% of adaptive plans and 79% of non-adaptive plans met the therapeutic goals. Additionally, adapted plans achieved therapeutic goals 69% more effectively compared to non-adapted plans.