Research on Automatic Measurement Method of Three-dimensional Gamma Dose Rate Radiation Field Based on VSLAM

Abstract

To address the need for rapid acquisition of gamma radiation field information in nuclear facility sites and digital radiation protection systems, simultaneous localization and mapping (SLAM) technology was combined with gamma dose detection technology in this paper. This combination aims to solve the problem of efficiently measuring gamma dose rate radiation fields in indoor scenarios while ensuring compatibility with digital systems. The study leverages the characteristics of scene sensors, focusing on visual SLAM (VSLAM) algorithms and methods for synchronizing and locating radiation measurement data using an RGBD camera. A gamma dose rate measurement device based on VSLAM was developed, employing an RGBD camera to capture the device motion trajectory and scene information. The gamma dose rate data was temporally and spatially matched with the trajectory test data by utilizing timestamps and the integral path midpoint method. This approach ensures precise synchronization between the spatial data from the VSLAM system and the temporal data from the gamma dose measurements. The quality of the scene point cloud, the accuracy of trajectory localization, and the performance of the gamma dose rate detection module were thoroughly tested. The measurement efficiency, localization accuracy, and compatibility with digital systems were analyzed at the experiments conducted at a nuclear facility site. The results show that more than 80% of the VSLAM scene point cloud matches the reference point cloud with a nearest neighbor distance of less than 0.2 m. This high level of accuracy in point cloud matching indicates that the VSLAM system can reliably reconstruct the 3D environment of the nuclear facility. The average matching distance between the measured trajectory and the motion capture system trajectory is 4.2 cm, with a standard deviation of 0.4 m. This demonstrates the high precision of the trajectory localization achieved by the VSLAM system. Within a dose rate range of 20 μGy/h to 20 mGy/h, the relative error in dose rate measurement is less than ±5%, indicating the reliability of the gamma dose detection module. Compared to traditional measurement methods, the new method improves the measurement efficiency of radiation dose rate fields by 10 times. This significant enhancement in efficiency can greatly reduce the time and effort required for radiation monitoring in nuclear facilities. The average matching distance between the measured trajectory and traditional tracking equipment (total station) was 18 cm, further validating the accuracy of the SLAM-based approach. Integration with digital systems achieves 3D spatial interpolation of radiation fields, with a single gamma source localization error of less than 0.8 m. This integration allows for a comprehensive visualization and analysis of radiation fields, facilitating better decision-making for radiation protection and safety. The developed VSLAM gamma dose rate measurement method and corresponding device offer high measurement efficiency, accurate localization, and good compatibility with digital systems, indicating a broad application prospect in the field of nuclear safety and radiation protection.

Keywords

• vslam
• γ radiation dose
• 3d radiation mapping
• digital systems