1. Department of Radiotherapy, Cangzhou Central Hospital, Cangzhou, Hebei 061001, P.R. China
2. Department of Dermatology, Cangzhou City People's Hospital, Cangzhou, Hebei 061000, P.R. China
3. Department of Gynaecology and Obstetrics, Tianjin Hospital, Tianjin 300211, P.R. China
4. Department of Anesthesiology, Tianjin Institute of Anesthesiology, General Hospital of Tianjin Medical University, Tianjin 300052, P.R. China