Abstract
PURPOSE: This study proposes a multidimensional hybrid twin navigation system to enhance applicator placement accuracy in low-energy x-ray intraoperative radiotherapy (kV-IORT), particularly for less-experienced practitioners. The system integrates augmented reality (AR) and digital twin technologies to improve intraoperative precision and usability. METHODS: The system comprises three core modules: (1) a holographic dose (Holo-dose) model visualizing clinically relevant radiation layers based on Zeiss TARGIT data, (2) a patient-specific applicator positioning strategy with real-time AR feedback adapted to tumor bed geometry, and (3) a bidirectional hybrid twin control linking a physical radiotherapy robot with its virtual twin for precise navigation. Phantom experiments utilized a 20 mm spherical applicator within a 30 mm tumor bed boundary. Target dose range was 18.50-19.50 Gy (15 mm radius) over 25 min. Accuracy was evaluated via root mean square error (RMSE) and target registration error (TRE). Mean RMSE was 0.383 mm (phantom) and 0.106 mm (robot); mean TRE was 0.41 mm. RESULTS: The system significantly enhanced positioning accuracy for novice users. Medical students achieved an average precision of 2.971 mm (p = 0.00015), and inexperienced physicians reached 2.803 mm (p = 0.00038). No significant improvement was observed for experienced surgeons (p > 0.05), indicating the system's potential as a training and assistance tool. The average System Usability Scale (SUS) score was 83.5, suggesting high user satisfaction, especially among younger participants. CONCLUSIONS: The hybrid twin navigation system significantly improved applicator placement accuracy for novice users, demonstrating its value as an effective training and assistance tool for kV-IORT. High user satisfaction and sub-millimeter registration and alignment accuracy confirm its potential for clinical translation, particularly in enhancing usability and precision for less-experienced practitioners.