Wayne R. Hedrick, PhD, Professor, Medical Radiation Biophysics, College of Medicine, Northeastern Ohio University, Rootstown, OH, USA; Certified Diagnostic Radiological and Medical Nuclear Physicist, Aultman Hospital, Canton, OH, USA, David L. Hykes, PhD, Consultant Medical Physicist, Medical Physics Services, Inc., Canton, OH, USA and Dale E. Starchman, PhD, Professor, Medical Radiation Biophysics, College of Medicine, Mortheastern Ohio Universities, Rootstown, OH, USA