Pancreatic SABR using peritumoral fiducials, triggered imaging and breath-hold

• Published in: Pathology oncology research 2023, Vol.29, p.1611456-1611456
• Main Authors: Kisivan, Katalin, Farkas, Andrea, Kovacs, Peter, Glavak, Csaba, Lukacs, Gabor, Mahr, Karoly, Szabo, Zsolt, Csima, Melinda Petone, Gulyban, Akos, Toth, Zoltan, Kaposztas, Zsolt, Lakosi, Ferenc
• Format: Article
• Language: English
• Subjects: Breath Holding; deep inspiration breath hold; Humans; Induction Chemotherapy; Kaplan-Meier Estimate; motion control; Pancreas; pancreatic cancer; Radiosurgery; stereotactic ablative radiotherapy; triggered imaging
• ISSN: 1532-2807; 1532-2807
• DOI: 10.3389/pore.2023.1611456

We aim to present our linear accelerator-based workflow for pancreatic stereotactic ablative radiotherapy (SABR) in order to address the following issues: intrafractional organ motion management, Cone Beam CT (CBCT) image quality, residual errors with dosimetric consequences, treatment time, and clinical results. Between 2016 and 2021, 14 patients with locally advanced pancreatic cancer were treated with induction chemotherapy and SABR using volumetric modulated arc therapy (VMAT). Internal target volume (ITV) concept (5), phase-gated (4), or breath hold (5) techniques were used. Treatment was verified by CBCT before and after irradiation, while tumor motion was monitored and controlled by kV triggered imaging and beam hold using peritumoral surgical clips. Beam interruptions and treatment time were recorded. The CBCT image quality was scored and supplemented by an agreement analysis (Krippendorff's-α) of breath-hold CBCT images to determine the position of OARs relative to the planning risk volumes (PRV). Residual errors and their dosimetry impact were also calculated. Progression free (PFS) and overall survival (OS) were assessed by the Kaplan-Meier analysis with acute and late toxicity reporting (CTCAEv4). On average, beams were interrupted once (range: 0-3) per treatment session on triggered imaging. The total median treatment time was 16.7 ± 10.8 min, significantly less for breath-hold vs. phase-gated sessions (18.8 ± 6.2 vs. 26.5 ± 13.4, < 0.001). The best image quality was achieved by breath hold CBCT. The Krippendorff's-α test showed a strong agreement among five radiation therapists (mean K-α value: 0.8 (97.5%). The mean residual errors were