1. Department of Medical Physics; Graduate School of Medical Science; Kindai University; Osakasayama 589-8511 Japan
2. Clinical Radiology Service Division; Kindai University Hospital; Osakasayama 589-8511 Japan
3. Division of Clinical Radiology Service; Okayama Central Hospital; Okayama 700-0017 Japan
4. Clinical Radiology Service Division; Kyoto University Hospital; Kyoto 606-8507 Japan
5. Department of Therapeutic Radiology; Nagoya University Graduate School of Medicine; Nagoya 466-8550 Japan