1. From the Departments of Radiology (A.M.F., M.K., L.H.B., K.S., J.M.J., J.K., S.B.P., T.J.B., S.A.H., A.B.M., R.M.S.) and Medical Physics (A.M.F., R.M.S.), University of Wisconsin School of Medicine and Public Health, 600 Highland Ave, Madison, WI 53792-3252; and University of Wisconsin Carbone Cancer Center, Madison, Wis (A.M.F., R.M.S.).