WE‐DE‐BRA‐10: Development of a Novel Scanning Beam Low‐Energy Intraoperative Radiation Therapy (SBIORT) System for Pancreatic Cancer

Abstract

Purpose:Developing a compact collimator system and validating a 3D surface imaging module for a scanning beam low‐energy x‐ray radiation therapy (SBIORT) system that enables delivery of non‐uniform radiation dose to targets with irregular shapes intraoperatively.Methods:SBIORT consists of a low energy x‐ray source, a custom compact collimator module, a robotic arm, and a 3D surface imaging module. The 3D surface imaging system (structure sensor) is utilized for treatment planning and motion monitoring of the surgical cavity. SBIORT can deliver non‐uniform dose distributions by dynamically moving the x‐ray source assembly along optimal paths with various collimator apertures. The compact collimator utilizes a dynamic shutter mechanism to form a variable square aperture. The accuracy and reproducibility of the collimator were evaluated using a high accuracy encoder and a high resolution camera platform. The dosimetrical characteristics of the collimator prototype were evaluated using EBT3 films with a Pantak Therapax unit. The accuracy and clinical feasibility of the 3D imaging system were evaluated using a phantom and a cadaver cavity.Results:The SBIORT collimator has a compact size: 66 mm diameter and 10 mm thickness with the maximum aperture of 20 mm. The mechanical experiment indicated the average accuracy of leaf position was 0.08 mm with a reproducibility of 0.25 mm at 95% confidence level. The dosimetry study indicated the collimator had a penumbra of 0.35 mm with a leaf transmission of 0.5%. 3D surface scans can be acquired in 5 seconds. The average difference between the acquired 3D surface and the ground truth is 1 mm with a standard deviation of 0.6 mm.Conclusion:This work demonstrates the feasibility of the compact collimator and 3D scanning system for the SBIORT. SBIORT is a way of delivering IORT with a compact system that requires minimum shielding of the procedure room.This research is supported by the University of Iowa Internal Funding Initiatives