3D<i>π</i>: three-dimensional positron imaging, a novel total-body PET scanner using xenon-doped liquid argon scintillator

<i>Objective.</i>This paper introduces a novel PET imaging methodology called 3-dimensional positron imaging (3D<i>π</i>), which integrates total-body coverage, time-of-flight (TOF) technology, ultra-low dose imaging capabilities, and ultra-fast readout electronics inspired by emerging technology from the DarkSide collaboration.<i>Approach.</i>The study evaluates the performance of 3D<i>π</i>using Monte Carlo simulations based on NEMA NU 2-2018 protocols. The methodology employs a homogenous, monolithic scintillator composed of liquid argon (LAr) doped with xenon (Xe) with silicon photomultipliers (SiPMs) operating at cryogenic temperatures.<i>Main results.</i>Substantial improvements in system performance are observed, with the 3D<i>π</i>system achieving a noise equivalent count rate of 3.2 Mcps at 17.3 kBq ml^-1, continuing to increase up to 4.3 Mcps at 40 kBq ml^-1. Spatial resolution measurements show an average FWHM of 2.7 mm across both axial positions. The system exhibits superior sensitivity, with values reaching 373 kcps MBq^-1with a line source at the center of the field of view. Additionally, 3D<i>π</i>achieves a TOF resolution of 151 ps at 5.3 kBq ml^-1, highlighting its potential to produce high-quality images with reduced noise levels.<i>Significance.</i>The study underscores the potential of 3D<i>π</i>in improving PET imaging performance, offering the potential for shorter scan times and reduced radiation exposure for patients. The Xe-doped LAr offers advantages such as fast scintillation, enhanced light yield, and cost-effectiveness. Future research will focus on optimizing system geometry and further refining reconstruction algorithms to exploit the strengths of 3D<i>π</i>for clinical applications.