1. From the Interdisciplinary Graduate Program in Radiation Sciences (M.L.L.), Department of Physics and Astronomy (D.R.C., F.E.M.), McMaster School of Biomedical Engineering (M.D.N.), and Department of Electrical and Computer Engineering (M.D.N.), McMaster University, 1280 Main St W, Hamilton, ON, Canada L8S 4L8; and Department of Physics, Ryerson University, Toronto, Ontario, Canada (J.L.G.).