Kernel-integration scatter model for the characterization of nuclear waste drums by gamma emission tomography
The objective of this study is the determination of the distribution of the activity of radio-elements contained in radioactive waste packages by means of single photon emission computed tomography (SPECT). A three-dimensional (3D) projector simulator for a parallel hole collimator and NaI(Tl) scintillator, based on the point kernel integration method is proposed, The model takes into account the attenuation and scatter of gamma rays. Primary scattered photons are treated by the Compton process and Klein-Nishina formula and the multiple scattering is accounted for by means of the dose buildup factor normally used in shielding problems. An advantage of the proposed model is that it offers the possibility of generating a full two-dimensional point-spread function (PSF) that can be used for 3D reconstruction. The developed model is convenient in those situations where more exact techniques (Such as Monte Carlo simulation) are not economical. The model has been evaluated for the package ha...ving homogenous density with the Cs-137 point source inside.