title: Geometrical parameters and scattered radiation effects on the extrinsic sensitivity and counting efficiency of a rectangular gamma camera.
abstract: A point source is used to investigate the effect of water phantom thickness and source-to-detector distance (SDD) on the sensitivity and counting efficiency of a rectangular detector gamma camera. The increase in water thickness resulted in an increase in scatter fraction, a decrease in sensitivity, and counting efficiency. The increase in SDD resulted in a decrease in sensitivity and an increase in counting efficiency. An SDD of 0.79±0.02m is found to provide a good compromise for acceptable sensitivity and reasonable counting efficiency.
authors.affiliation: Physics Department, Faculty of Science, Assiut University, Egypt.
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: Ghoneim
authors.affiliation: Physics Department, Faculty of Science, Helwan University, Egypt.
authors.forename: M H
authors.initials: MH
authors.lastname: Khedr
authors.affiliation: Biophysics Department, Faculty of Science, Cairo University, Egypt.
authors.forename: Wael M
authors.initials: WM
authors.lastname: Elshemey
keywords: Calibration; Counting efficiency; Extrinsic sensitivity; Gamma camera; Scattered fraction