ESTRO 2025 - Abstract Book

S4376

RTT - Treatment planning, OAR and target definitions

ESTRO 2025

Figure 1 shows the deviation between the 3D-3D and 3D-2D registration. A wider range of deviations is seen in the bTFE-cine. Figure 2 shows a preference of the T2-TSE-cine over the bTFE-cine in terms of the VGA metrics. The equivalent continuous sound level for the bTFE-cine and T2-TSE-cine were 110.7 dB and 100.1 dB respectively. Conclusion: This study shows a higher accuracy, improvement of image quality and lower acoustic noise levels of the T2-TSE cine sequence over the bTFE-cine used for intrafraction drift correction workflows of pelvic targets on the 1.5T MR Linac and therefore allowing for potentially smaller PTV margins and extreme hypofractionation. Furthermore, the lower overall equivalent acoustic noise level of the T2-TSE-cine compared to the bTFE-cine, contributes to higher comfort for patients. This T2-TSE-cine sequence is available in the newest MR 5.8.1. release at the Unity.

Keywords: MR-Linac, intrafraction motion correction, cine