  Positron Emission Tomography (PET) is a widely-used imaging modality for
medical research and clinical diagnosis. Here we demonstrate, through detailed
experiments and simulations, an exploration of the benefits of exploiting the
quantum entanglement of linear polarisation between the two positron
annihilation photons utilised in PET. A new simulation, which includes the
predicted influence of quantum entanglement on the interaction of MeV-scale
photons with matter, is validated by comparison with experimental data from a
cadmium zinc telluride (CZT) PET demonstrator apparatus. In addition, a
modified setup enabled the first experimental constraint on entanglement loss
for photons in the MeV regime. Quantum-entangled PET offers new methodologies
to address key challenges in next generation imaging. As an indication of the
potential benefits, we present a simple method to quantify and remove
in-patient scatter and random backgrounds using only the quantum entanglement
information in the PET events.
