Semi-empirical Scatter Correction Models for High-speed Gamma- Ray Tomography

R. Maad1,2, B. T Hjertaker2, G. A. Johansen2

1Sogn og Fjordane College, Faculty of Engineering, N-6800 Førde, Norway.

E-mail: rachid.maad@hisf.no

2University of Bergen, Department of Physics and Technology, Allégaten 55, N-5007 Bergen, Norway, E-mail: geir.johansen@ift.uib.no

ABSTRACT

Scattered radiation decreases the signal to noise ratio and the contrast of gamma-ray transmission tomography, by introducing errors in the measured tomography data and consequently, in the reconstruction algorithm. In order to minimize the effect of scattered radiation on the multi-channel gamma-ray tomograph, collimator blades of lead are placed in front of each detector. Furthermore, scattered photons of lower energy are discriminated by a threshold scheme in the detector electronics unit. In this paper, the effect and contribution of the scattered radiation, emerging from the multiple low energy gamma-ray sources of the high-speed gamma-ray tomograph at the University of Bergen (UoB), is presented. The scattered radiation has been measured using different phantoms inside the tomograph. The results of these measurements are presented along with radiation scatter calculations using a semi-empirical model.

Keywords Gamma-ray tomography, Compton scattering, scatter correction, semi empirical scatter model.