Different authors publish about the transmission curves as a function of shielding material thickness. It is important to define these curves of transmission of photons using the material composition available and regularly commercialized. So the objective of this work was to simulate the transmission data and to generate the transmission curves as function of different material composition as function of the thickness to the spectrum energy used on PetCT. That way we simulate an incoming monoenergetic photons beam of 511 keV. Were collected in sensitive volume the absorbed energy and the photon flux on spherical sensitive volume with a radius of 1.0cm composed of air. We simulated two sensitive volumes one before and one after the shielding wall. We simulate shielding wall made of: lead; concrete, described according Simpkin and ICRU 44 documentation; iron alloy composed by 1% of carbon and barite mortar. The curves of transmission were compared to other simulated data and to real data. As results we generate a group of data and fitting curves applied to the medical application getting concordance to the previously published data and the real data collected. We generated curves of transmission data for barite mortar, undefined for these applications until now.