A Monte Carlo–Based Digital Twin Platform for Integrated PET/CT-Linac Imaging and Radiation Transport Simulation
Abstract
Purpose
Integrated PET/CT-LINAC systems enable functional imaging and radiation delivery within a unified geometry, providing a unique platform for imaging-guided radiotherapy. Rigorous investigation of such systems requires a physics-consistent simulation framework capable of jointly modeling PET imaging performance and radiation transport processes. This study aims to develop a Monte Carlo–based PET/CT-LINAC digital twin simulation framework to support system-level performance evaluation and future PET-guided radiotherapy research.
Methods
A unified digital simulation platform was developed using the GATE Monte Carlo toolkit. Accurate geometric and physical models of a whole-body PET/CT system and a linear accelerator were constructed, incorporating detector configuration, scintillation properties, coincidence timing, and acquisition parameters. These components were integrated to establish a coupled PET/CT-LINAC simulation environment. Key PET performance metrics, including sensitivity and spatial resolution, were evaluated under different activity levels and acquisition conditions. In addition, radiation dose distributions deposited in geometric phantoms were simulated to assess the radiation transport component. Simulation results were compared with reported system specifications to evaluate model accuracy, numerical stability, and reproducibility.
Results
The simulated PET/CT-LINAC system demonstrated good agreement with reference system performance. The digital twin accurately reproduced sensitivity trends, high spatial resolution characteristics, and physically reasonable radiation dose distributions across multiple simulated conditions. Stable and reproducible results were consistently observed, indicating that the integrated PET/CT-LINAC digital twin provides a coherent and reliable platform for combined imaging and radiation transport analysis.
Conclusion
The proposed Monte Carlo–based PET/CT-LINAC digital twin simulation framework offers a robust and physics-consistent tool for integrated imaging and therapy studies. It enables comprehensive system-level performance evaluation and establishes a validated foundation for future investigations of PET-guided radiotherapy and imaging–therapy integration.