1. Department of Ultrasound, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266000, P.R. China
2. Physical Examination Department, People's Hospital of Rizhao, Rizhao, Shandong 276800, P.R. China
3. Sterilization Supply Room, The People's Hospital of Zhangqiu Area, Jinan, Shandong 250200, P.R. China
4. Health Management Center, The People's Hospital of Zhangqiu Area, Jinan, Shandong 250200, P.R. China
5. Outpatient Department, The People's Hospital of Zhangqiu Area, Jinan, Shandong 250200, P.R. China