S2698
RTT - Patient preparation, immobilisation, and verification protocols
ESTRO 2026
alternate days thereafter for analyzing the data for setup errors. Results: The mean interfraction translation shifts for daily imaging by CBCT were 2.0 mm, 2.2 mm and 1.1mm in the S-I (Sup-Inf), L-R (Left-Right) and A-P (Ant-Post) direction, respectively. Also the rotation errors were between 1.3 to 1.5 deg. in all directions. On the other hand the mean shifts with SGRT (ETD) were 0.9mm, 1.2mm, and 0.4 mm in the S-I, L-R and A-P direction, respectively. Similarly the rotation errors were found between 0.6 to 1.0 deg. in all directions. Results show that SGRT significantly reduced initial positioning errors compared to laser based conventional methods. Conclusion: This precision is vital in H&N radiotherapy even small errors in patient positioning can significantly impact treatment outcomes and increase the risk of side effects.Studies show both CBCT and SGRT provide acceptable treatment accuracy in H&N cancers. But the Thermo-optical surface imaging system combined with room-based stereoscopic X - ray image guidance (ETD-IGRT) for image verification offers advantages like improved patient comfort, increased accuracy, reduced treatment time and imaging dose. References: 1. Shift detection discrepancy between ExacTrac Dynamic system and cone-beam computed tomography (Vivian U Y Chow, Michael L M Cheung, Monica W K Kan, Anthony T C Chan)2. Clinical Experience of Intrafractional Motion Monitoring of Patients Under Head and Neck Radiation Therapy Using ExacTrac Dynamic System (Vivian U.Y.Chow, Michael L.M. Cheung, Monica W.K.Kan, Anthony T.C. Chan MD, FRCP)3.Stereoscopic X-ray imaging, cone beam CT, and couch positioning in stereotactic radiotherapy of intracranial tumors: preliminary results from a cross-modality pilot installation (Barbara Zollner, Christian Heinz, Sabrina Pitzler, Farkhad Manapov, Steffi Kantz, Maya Christine Rottler, Maximilian Niyazi, Ute Ganswindt, Claus Belka, Hendrik Ballhausen) Keywords: VERIFICATION ,SGRT , HEAD & NECK IMMOBILIZATION
demonstrating clear site-specific ranges. This framework enables ROI personalisation, objective ROI QA, facilitates RTT training, and helps prospectively flag outlier anatomy before treatment. References: Malone C, Ryan S, Nicholson J, Brennan SM. From rugged ridges to radiotherapy ROIs: Translating topographical metrics to Surface-Guided Radiation Therapy regions of Interest in radiotherapy. Radiother Oncol. Published online October 9, 2025:111173.
doi:10.1016/j.radonc.2025.111173 Keywords: SGRT, ROI, topography
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Advancing Image-Guided Radiotherapy with Thermo-Optical Surface Imaging and real time Stereoscopic X-Ray: Precision without Additional Dose RAKESH KAUL Radiation Oncology, Max Cancer Hospital, New Delhi, India Purpose/Objective: Radiation treatment plays a crucial role in the H&N cancers in ensuring delivery of dose with high precision, using laser based patient positioning alignment system and verified by portal imaging or (CBCT) and compare setup errors with thermo-optical surface imaging (SGRT) system combined with room- based stereoscopic X - ray image guidance (IGRT) for image verification. We at our center have The Edge linear accelerator by Varian with integrated ExacTrac Dynamic (ETD) system (Brainlab SE, Munich, Germany) which offers advanced features for precise and efficient cancer treatment.Thermo-optical surface imaging system combined with room-based stereoscopic X - ray image guidance offers precise patient positioning, improved treatment accuracy, reduced overall treatment time and hybrid approach of ExacTrac Dynamic offers more comprehensive view of the patient positioning and real time monitoring in comparison to kV-CBCT alone. It is noninvasive and non-ionization and reduces the need for volumetric imaging during verification. Material/Methods: 42 patients with H&N cancer were randomly picked up for study. Radiation dose of 70Gy in 35 fractions was delivered on EDGE- Linear accelerator. For All patients 5 clamp H&N thermoplastic mask were used as immobilization device. A total of 252 CBCT images were evaluated for patient setup verification and compared with Stereoscopic x-ray image verification after initial setup with SGRT on ETD. These images are obtained at first three days of treatment and then on
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Assessment of Intrafractional Displacements in Surface-Guided Deep Inspiration Breath-Hold Stereotactic Body Radiation Therapy Domagoj Brki ć , Hrvoje Kau č i ć Radiotherapy, Specialty Hospital Radiochirurgia Zagreb, Sveta Nedelja, Croatia
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