Performance evaluation of a preclinical all-digital positron emission particle tracking system

Objective. Positron-emission particle tracking (PEPT) is increasingly used for in vivo applications such as tracking single cells or micro-scale probes in deep tissue. To support such biomedical studies, this work evaluates whether a reconfigured, all-digital small-animal PET system can provide the count-rate capacity, sensitivity, and sub-millimetre spatial tracking precision required for accurate PEPT under realistic in vivo conditions. Approach. System performance was tested with 18 F point sources across multiple conditions: count-rate and sensitivity were measured using a central decaying source and axial scans; localisation precision was then evaluated for static, shielded sources in various materials and for moving sources at two speeds, with the algorithm parameters were tuned based on the system's coincidence rate and tracer speed to minimise localisation error. Main results. The system maintained linear count-rate behaviour up to ~25 MBq and handled prompt rates up to 3.4 MHz. System axial sensitivity peaked at 3.45 %, and static localisation precision was uniform (~0.6 mm) over a 100 mm range and remained <1 mm even with tissue-or bone-equivalent shielding. In dynamic tracking, parameter tuning based on system characteristics and tracer velocity yielded optimal localisation precisions of 0.62 mm (144 mm/s) and 0.64 mm (425 mm/s), with increasing window width N shown to degrade accuracy if not matched to motion conditions. Significance. The evaluated system delivers sub-millimetre localisation precision across a wide FOV and retains accuracy in the presence of attenuation and motion. These results support its application to in vivo cell and particle tracking and provide practical guidance for tuning PEPT parameters based on scanning conditions, greatly extending the potential for PEPT studies.