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In this work we investigate the effects due to photon attenuation and scattering in a Positron Emission Mammography (PEM) study using the GATE (Geant4 Application for Tomographic Emission) Monte Carlo (MC) code. Breast phantoms with different shapes and volumes placed within a scanner geometry similar to IFUNAM’s PEM prototype under development were considered. The results show that attenuation and scatter effects for 511 keV photons depend strongly on the breast phantom volume (and thus, breast thickness). For breast volumes between 200 and 950 ml, scatter contributions vary from 24% to 58%, while the attenuation of primary photons are significant, within 36% and 73%. Our results indicate, overall, that the larger the breast volume, the larger these effects. This implies that for a clinical study to provide precise and quantitative information, complex corrections pre- or post- image reconstruction must necessarily be implemented. |
