1. Engineering Research Center of Molecular and Neuro‐imaging of Ministry of Education School of Life Science and Technology Xidian University Xi'an Shaanxi 710126 P. R. China
2. Department of Thoracic Surgery Shanghai Pulmonary Hospital School of Medicine Tongji University Shanghai 200433 P. R. China
3. Academy of Advanced Interdisciplinary Research Xidian University Xi'an Shaanxi 710071 P. R. China
4. Department of Radiotherapy Chinese PLA General Hospital Beijing 100071 P. R. China