1. Department of Health Policy and Management, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, United States,
2. Institute for Hospital Management, School of Medicine, Tsinghua University, Beijing, China,
3. Department of Radiology, School of Clinical Medicine, Beijing Tsinghua Changgung Hospital, Tsinghua University, Beijing, China,
4. Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, China,