1. Department of Experimental Nuclear Medicine, Guangzhou Medical University, Guangzhou, Guangdong, China
2. Department of Radiation Oncology, Guangzhou Medical University, Guangzhou, Guangdong, China
3. School of Photonics and Electronic Engineering, Fujian Normal University, Fuzhou, Fujian, China
4. Department of Radiation Oncology and Electronic Engineering, University of Colorado Denver, Denver, CO, USA