1. Department of Radiation Oncology , , 21-1 Hongo, Bunkyo-ku, Tokyo 113-8421 , Japan
2. Juntendo University, Graduate School of Medicine , , 21-1 Hongo, Bunkyo-ku, Tokyo 113-8421 , Japan
3. Department of Radiological Technology , , 21-1 Hongo, Bunkyo-ku, Tokyo 113-8421 , Japan
4. Juntendo University , , 21-1 Hongo, Bunkyo-ku, Tokyo 113-8421 , Japan
5. Medical Technology Innovation Center , , 21-1 Hongo, Bunkyo-ku, Tokyo 113-8421 , Japan
6. Department of Radiology , , 21-1 Hongo, Bunkyo-ku, Tokyo 113-8421 , Japan
7. Juntendo University Hospital , , 21-1 Hongo, Bunkyo-ku, Tokyo 113-8421 , Japan
8. Misugikai Satou Hospital, Department of Radiation Oncology , 65-1 Yabuhigashimachi, Hirakata-shi, Osaka 573-1124, Japan