1. Department of Mechanical Engineering, Chang Gung University, Taoyuan 333, Taiwan
2. Department of Biomedical Engineering, Chang Gung University, Taoyuan 333, Taiwan
3. Department of Periodontics, Chang Gung Memorial Hospital, Taipei 105, Taiwan
4. Accelerator Laboratory, Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu 300, Taiwan
5. Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 300, Taiwan
6. Department of Radiation Oncology, Chang Gung Memorial Hospital, Taoyuan 333, Taiwan
7. Department of Medical Imaging and Radiological Science, Chang Gung University, Taoyuan 333, Taiwan
8. Proton and Radiation Therapy Center, Linkou Chang Gung Memorial Hospital, Taoyuan 333, Taiwan
9. Department of Mechanical Engineering, Ming Chi University of Technology, New Taipei City 243, Taiwan