Artifacts in digital coincidence timing.

Area of Science:

• Medical Imaging
• Nuclear Instrumentation
• Signal Processing

Background:

• Digital methods are standard for time difference measurements in PET cameras.
• These methods rely on a master clock and digitized detector arrival times.
• Time differences are calculated by subtracting detector pair estimates.

Purpose of the Study:

• To demonstrate the origin of artifacts in digital timing measurements.
• To highlight potential errors in optimizing timing resolution.
• To advise caution when solely minimizing timing resolution.

Main Methods:

• Comparing detector output signals to a reference clock edge.
• Utilizing time-to-digital converters (TDCs) or waveform digitization.
• Measuring coincidence timing resolution to assess timing methods.

Main Results:

• A nonlinear transfer function can cause timing artifacts.
• These artifacts artificially narrow the timing resolution distribution.
• This can lead to the erroneous selection of an 'optimal' timing method.

Conclusions:

• Timing resolution minimization alone can be misleading.
• Nonlinear transfer functions create artifacts that affect optimization.
• Careful consideration of error sources is crucial for digital timing systems.