1. Biomedical Physics Laboratory, FPRD, School of Physics and Astronomy, Seoul National University, Seoul, Korea.
2. These authors contributed equally.
3. X-ray Imaging Center, I-BIO Program, Department of Materials Science and Engineering, Pohang University of Science and Technology, Korea.
4. Basic Research Institute, Seoul National University, Seoul, Korea.
5. Norris Comprehensive Cancer Center and Department of Surgery, University of Southern California, Los Angeles, California.