1. Department of Anatomy, Histology and Embryology, School of Basic Medical Science, Shandong University, Jinan, Shandong 250012, P.R. China
2. Department of Radiotherapy, Shandong Provincial Qianfoshan Hospital, The First Hospital Affiliated with Shandong First Medical University, Jinan, Shandong 250014, P.R. China
3. Department of Special Examination, Penglai People's Hospital, Penglai, Shandong 265600, P.R. China
4. Department of Oncology, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, Shandong 250021, P.R. China