Affiliation: | (1) Department of Clinical Physics and Bioengineering, Walsgrave Hospital, Coventry, England;(2) Department of Engineering, University of Warwick, Coventry, England;(3) Present address: Regional Department of Medical Physics and Bioengineering, Christie Hospital and Holt Radium Institute, Wilmslow Road, Withington, M20 9BX Manchester, England;(4) Present address: Department of Physics and Nuclear Medicine, Dudley Road Hospital, B18 7QH Birmingham, England |