Evaluating the Impact of Improved Timing Resolution Time of Flight PET on Image Quality Over a Range of Phantom Sizes

Abstract

Time-of-flight (TOF) positron emission tomography (PET) has been shown to improve image quality by enhancing localization of annihilation events, particularly in larger body sizes. This study evaluates the impact of improved timing resolution on TOF PET image quality across a range of phantom sizes using three PET/CT scanner models with diferent timing resolutions: 544 ps, 382 ps, and 215 ps. A large tapering phantom, representing different patient body sizes, was imaged at multiple cross-sectional areas. Images were reconstructed both with and without TOF information, and quantitative metrics—including contrast recovery coefficient (CRC), background variability (BGV), and contrast to noise ratio (CNR)—were assessed. Results demonstrated that improved timing resolution led to significant increases in CRC and reductions in BGV, particularly in larger phantom sizes. The highest timing resolution scanner, the Siemens Biograph Vision, exhibited the greatest TOF-related improvements at the largest phantom sizes. These findings confirm that improved TOF timing resolution enhances PET image quality and supports its continued advancement in clinical applications, particularly for larger patients.