1. Department of Radiological Technology, Tsuchiya General Hospital, Hiroshima 730-8655, Japan.
2. Department of Diagnostic Radiology, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima 734-0037, Japan.
3. Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan.
4. Department of Medical Physics, Faculty of Life Sciences, Kumamoto University, Kumamoto 860-8556, Japan.
5. Department of Diagnostic Radiology, Tsuchiya General Hospital, Hiroshima 730-8655, Japan.