Redundancy-weighted FDK reconstruction for dual-detector combined-scanning CBCT: Practical implementation for image guided particle therapy

Abstract

Background: Cone-beam computed tomography (CBCT) is essential for image-guided particle therapy (IGPT), providing daily patient positioning, anatomical monitoring, and treatment verification. However, conventional single-detector CBCT suffers from poor soft-tissue contrast, long acquisition times, and motion artifacts, reducing its effectiveness for adaptive radiotherapy workflows. Addressing these challenges requires an advanced CBCT reconstruction approach capable of enhancing image quality while reducing scan time and radiation exposure. Purpose: This study introduces a Dual Detector Combined Scanning (DDCS) CBCT reconstruction algorithm to overcome conventional CBCT limitations. By integrating a dual-source, orthogonal imaging setup, DDCS significantly reduces scanning time and imaging artifacts. A modified Parker-weighting algorithm further improves image reconstruction accuracy, ensuring high-fidelity visualization. The goal is to enhance adaptive radiotherapy by improving real-time patient positioning, dose verification, and motion management. Methods: A dual-detector CBCT system was designed to acquire orthogonal projections simultaneously, reducing scan time and improving data completeness. A modified Parker-weighting algorithm corrected angular overlap distortions, ensuring better reconstruction accuracy. The system was evaluated using numerical and physical phantom studies to assess spatial resolution, contrast-to-noise ratio (CNR), and artifact reduction. Additionally, a dynamic phantom simulated respiratory motion, validating motion robustness for adaptive radiotherapy. Performance was compared against single-detector CBCT, focusing on image fidelity, noise suppression, and computational efficiency. Results: DDCS-CBCT demonstrated higher CNR, reduced motion artifacts, and improved spatial resolution, leading to more accurate anatomical visualization. The system's efficiency enables faster, more reliable patient setup in IGPT while maintaining a lower imaging dose. Conclusion: The proposed DDCS-CBCT approach significantly improves imaging accuracy, reduces scan time, and enhances real-time volumetric guidance in IGRT/IGPT. These findings support the clinical feasibility of the DDCS system and its integration into online adaptive radiotherapy workflows. © 2025 American Association of Physicists in Medicine.