Time-of-Flight Requirements to Mitigate Blurring Induced by Annihilation Photon Acollinearity

Area of Science:

• Medical Imaging
• Nuclear Physics
• Instrumentation

Background:

• Annihilation photon acollinearity (APA) limits spatial resolution in positron emission tomography (PET) scanners.
• Long axial field-of-view (FOV) PET systems experience increased APA blur.
• Time-of-flight (TOF) resolution has the potential to mitigate APA-induced spatial resolution loss.

Purpose of the Study:

• To investigate the requirements for achieving observable spatial resolution gains in PET imaging.
• To explore the impact of TOF resolution and count statistics on APA mitigation.
• To assess TOF resolution needs for both whole-body and long axial FOV PET scanners.

Main Methods:

• Simulations using a fictive 81-cm diameter PET scanner with 2-mm detectors.
• Evaluation of varying TOF resolutions (13 ps, 27 ps, 67 ps FWHM).
• Analysis of spatial resolution improvements under different count statistics.

Main Results:

• Ultrafast TOF resolution (13 ps FWHM) demonstrated observable spatial resolution gains across various count statistics.
• Lower TOF resolutions (27 ps or 67 ps) can mitigate APA in long axial FOV systems with oblique lines of response.
• TOF precision shows potential for reducing the nonstationary nature of spatial resolution in PET.

Conclusions:

• Specific TOF resolution and count statistics are crucial for overcoming APA limitations in PET.
• Advanced TOF capabilities can enhance spatial resolution and mitigate non-uniformity in PET imaging.
• The findings provide insights into optimizing future PET scanner designs for superior image quality.