1. Center for General Education, Chang Gung University, Taoyuan 333, Taiwan
2. School of Medicine, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan
3. Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming Chiao Tung University, Taipei 112, Taiwan
4. Department of Radiation Oncology, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung 833, Taiwan
5. Institute for Radiological Research, Chang Gung University, Taoyuan 333, Taiwan