Timing performance evaluation of a dual-Axis rotational PET system according to NEMA NU 4-2008 standards: A simulation study

<i>Introduction:</i>Positron Emission Tomography (PET) imaging's diagnostic accuracy is dependent on the scanner design and image quality, which is affected by several factors including the coincidence timing window (CTW). NEMA NU 4-2008 procedures are commonly used to assess and compare PET systems performance, including dual rotation technologies like easyPET.3D, known for high-spatial resolution and reduced parallax contribution.<i>Aim:</i>This study aims to identify easyPET.3D's optimal performance based on NEMA standards. In addition, explores the impact of different CTWs on PET image quality by comparing simulated electronics capable of a 300 ps CTW with a 40 ns CTW.<i>Results:</i>When the data is filtered by a 40 ns CTW, a sub-millimetre resolution at the field-of-view (FoV) centre and a constant behaviour in the radial direction are achieved. The absolute sensitivity was 0.18% with a maximum value of 0.31%, for a 15 mm transverse FoV. The noise equivalent count rate peaked at 18 MBq with 249 cps. Recovery coefficients ranged from 17% to 90%, and spilled-over ratios were 0.32 (water) and 0.41 (air).<i>Conclusions:</i>A shorter 300 ps CTW primarily impacted PET dynamic range, allowing higher activity acquisitions, with no significant changes in resolution and sensitivity under NEMA test conditions. As for the image quality test, the 300 ps CTW images have less background, better SOR values, and similar RC values when comparing the 40 ns CTW.