Monte Carlo simulations of a ClearPET: Scatter and attenuation of gamma rays in various rock formations

Positron emission tomography (PET) is applied in geosciences for the visualization of flow and transport processes in various rock formations (GeoPET [1]). Denser rock material requires more demanding and stronger corrections of scatter and attenuation of the gamma rays than in human body tissue. Once the quantification of scatter and attenuation is acquired, correction strategies can be established and the physical limit of the spatial resolution of ~1 mm for the GeoPET method be accomplished. We suggest Monte Carlo (MC) simulations of a ClearPET camera (Raytest) as means for achieving this aim.

We report simulation results of the GeoPET using software GATE (Geant4 Application for Tomographic Emission [2]). The purpose of this investigation is to determine the scatter fraction of gamma rays in various rock formations with different gantry diameter configurations, various Isotopes and different energy windows.
The simulations show that the energy window and increasing gantry diameter are important physical parameters affecting the scatter fraction values in denser material. Reconstructed images from measurements and simulations show good qualitative agreement.
[1] Kulenkampff, J. et al. (2008) Phys. Chem. Earth 33, 937-942.
[2] Jan, S. et al. (2011) Phys. Med. Biol. (56) 881-901.