1. Department of Respiratory, Weifang Yidu Central Hospital, Weifang, Shandong 262500, P.R. China
2. Department of Respiratory, Weifang Yidu Central Hospital, Weifang, Shandong 262500, P.R. China
3. Department of Oncology, Weifang Yidu Central Hospital, Weifang, Shandong 262500, P.R. China
4. Department of Respiratory, Anqiu People's Hospital, Anqiu, Shandong 262100, P.R. China