1. Department of Radiology, Cathay General Hospital, Taipei 106, Taiwan, R.O.C.
2. Department of Medical Imaging and Radiology, Shu‑Zen Junior College of Medicine and Management, Kaohsiung 821, Taiwan, R.O.C.
3. Department of Radiation Oncology, Cheng Hsien General Hospital, Bei‑tou, Taipei 112, Taiwan, R.O.C.
4. Department of Radiation Oncology, Taipei City Hospital, Renai Branch, Taipei 242, Taiwan, R.O.C.
5. Department of Biomedical Imaging and Radiological Sciences, National Yang‑Ming University, Taipei 112, Taiwan, R.O.C.
6. Department of Radiation Oncology, Mackay Memorial Hospital, Taipei 104, Taiwan, R.O.C.