A new dual threshold time-over-threshold circuit for fast timing in PET

Area of Science:

• Medical Imaging
• Nuclear Physics
• Electronics Engineering

Background:

• Time-over-threshold (ToT) offers combined timing and energy encoding in PET.
• Conventional single threshold ToT exhibits nonlinear responses and poor timing/energy resolution tradeoffs.
• This limits its suitability for demanding applications like time-of-flight (ToF) PET.

Purpose of the Study:

• To investigate the efficacy of a dual threshold ToT method for enhanced PET imaging.
• To experimentally demonstrate improved timing resolution using a novel compact circuit design.
• To compare the performance of dual threshold ToT against conventional single threshold ToT.

Main Methods:

• Implementation of a novel compact circuit utilizing a dual threshold Time-over-threshold (ToT) technique.
• Experimental evaluation of timing resolution with 3 × 3 × 5 mm³ LYSO crystals.
• Comparative analysis of dual threshold ToT against single threshold ToT systems.

Main Results:

• Achieved excellent time resolution of 154 ps Full Width at Half Maximum (FWHM) with dual threshold ToT.
• Demonstrated significantly superior coincidence time resolution (154 ps vs. 418 ps) compared to single threshold ToT.
• Successfully developed and demonstrated a nonlinearity correction method for dual threshold ToT energy spectra.

Conclusions:

• Dual threshold ToT provides excellent timing resolution suitable for time-of-flight (ToF) PET.
• The new method overcomes limitations of single threshold ToT, offering superior performance.
• This advancement holds promise for improving the capabilities of PET imaging systems.