1. Center for In Vivo Microscopy, Department of Radiology, Duke University, 311 Research Dr, Durham, North Carolina 27710,
USA
2. Medical Physics Graduate Program, Duke University, 2424 Erwin Rd., Ste. 101, Durham, North Carolina 27710,
USA
3. Shared Materials Instrumentation Facility, Duke University, 101 Science Dr., Durham, North Carolina 27710,
USA