In this article, we investigate quantum entanglement (QE) filtering to address the challenges in multi-isotope positron emission tomography (PET) or in PET studies utilizing radiotracers with dual-positron and prompt gamma emissions. Via GATE simulation, we demonstrate the efficacy of QE filtering using a one-of-a-kind cadmium zinc telluride (CZT) PET system -establishing its viability as a multimodal scanner and ability to perform QE filtering. We show the high Compton scattering probability in this CZT-based scanner with 44.2% of gammas undergoing a single scatter prior to absorption. Additionally, the overall system sensitivity as a standard PET scanner (11.29%), QE-PET scanner (6.81%), and Compton Camera (11.29%) is quantified. Further, we find a 23% decrease in the double Compton scatter (DCSc) frequency needed for QE filtering for each mm decrease in crystal resolution and an increase in mean absolute error (MAE) of their ∆ϕs from 6.8 o for 1 mm resolution to 9.5 o , 12.2 o , and 15.3 o for 2, 4, and 8 mm resolution, respectively. These results reinforce the potential of CZT detectors to lead next generation PET systems taking full advantage of the QE information of positron annihilation photons.