1. National Council on Radiation Protection and Measurements, Bethesda, MD, USA
2. Departments of Medical Physics and Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
3. SLAC National Accelerator Laboratory, Menlo Park, CA, USA
4. Department of Radiology, University of New Mexico School of Medicine, Albuquerque,, NM, USA
5. Mayo Clinic, Rochester, MN, USA