ESTRO 2024 - Abstract Book

S3729

Physics - Dose prediction, optimisation and applications of photon and electron planning

ESTRO 2024

1 Inselspital, Bern University Hospital, and University of Bern, Division of Medical Radiation Physics and Department of Radiation Oncology, Berne, Switzerland. 2 Varian Medical Systems Imaging Laboratory GmbH, Varian, Baden, Switzerland

Purpose/Objective:

Dynamic trajectory radiotherapy (DTRT) is an investigational radiotherapy delivery technique, which extends standard-of-care volumetric modulated arc therapy (VMAT) by dynamic table and collimator rotation during beam-on. DTRT has shown improved healthy tissue sparing compared to VMAT. However, there are concerns that dynamic motion of the treatment table may induce motion sickness. The aim of this study was to compare motion sickness induced by DTRT to non-coplanar VMAT (ncVMAT) in healthy volunteers, testing for non-inferiority.

Material/Methods:

In this prospective phase I, randomized, open-label, non-inferiority crossover trial, healthy volunteers were randomly assigned in a 1:1:1:1 ratio to undergo dry-runs (reproducing mechanical motion of treatment plan delivery without beam-on) of DTRT (D) or ncVMAT (V) treatment plans simulating oropharyngeal cancer treatment in four different sequences (DDVV / VVDD / DVVD / VDDV). Volunteers filled in the motion sickness assessment questionnaires (MSAQ 1 ) before and after each of the four dry-runs with 45 min for wash-out between runs. Analysis was performed on the intention-to-treat population. The primary outcome was overall motion sickness score differences (defined as the summary score of the MSAQ questionnaire post- minus pre-run) with a non inferiority margin of 4 points. Non-inferiority was assessed by computing mean and 95% confidence intervals of the primary outcome and comparing between DTRT and ncVMAT. Secondary endpoints were differences in MSAQ sub-scores (mean score in questionnaire items describing gastro-intestinal (GI), central (C), peripheral (P), or sopite-related (S) symptoms) and clinically relevant motion sickness.

Results:

Of 41 volunteers who underwent randomization, 40 completed all four dry-runs without protocol deviations. Table 1 describes the study demographics. Mean [95% confidence interval, CI] MSAQ summary score differences were 2.52 [1.42 - 3.63] after DTRT dry-runs and 1.62 [1.06 - 2.18] after ncVMAT dry-runs. Mean MSAQ sub-score differences were 0.13, 0.32, 0.01, 0.17 for GI, C, P, S after DTRT dry-runs and 0.07, 0.23, <0.01, 0.12 for GI, C, P, S after ncVMAT dry-runs. One adverse event (self-limiting clinically symptomatic motion sickness) was reported after one DTRT dry-run (0.6%) and none after ncVMAT dry-runs. No serious adverse events were reported.