1 Medical Physics and Informatics Laboratory, Department of Electronics Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung 807, Taiwan.
2 Department of Radiation Oncology, Institute for Advanced Radiation Oncology, Monmouth Medical Center, Barnabas Health, Long Branch, NJ 07740, USA.
3 Department of Radiation Oncology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University, College of Medicine, Kaohsiung 833, Taiwan.
4 Department of Medical Imaging and Radiological Sciences, Chang Gung University, Taoyuan 333, Taiwan.
5 Medical Physics Department, Memorial Sloan-Kettering Cancer Center, 136 Mountain View Boulevard, Basking Ridge, NJ 07920, USA.
6 Department of Radiation Oncology, City of Hope National Medical Center, Duarte, CA 91010, USA.