Improved Edge Pixel Resolution in Modular PET Detectors with Partly Segmented Light Guides

Area of Science:

• Medical Imaging Physics
• Instrumentation Science

Background:

• Positron Emission Tomography (PET) sensor modules exhibit an "edge effect" due to asymmetric optical photon distribution near module edges.
• This effect causes errors in scintillation event coordinate reconstruction using center-of-gravity (CoG) algorithms, leading to overlapping signatures and image artifacts.

Purpose of the Study:

• To mitigate the PET "edge effect" and improve coordinate reconstruction accuracy.
• To evaluate the efficacy of partly segmented light guides in addressing photon spread.

Main Methods:

• Utilized partly segmented borosilicate light guides filled with barium sulfate to confine optical photons.
• Performed data acquisition using single PET sensor modules in coincidence with single and multiplexed channel readout.
• Employed center-of-gravity (CoG) and truncated center-of-gravity (TCoG) methods for coordinate reconstruction.

Main Results:

• Partly segmented light guides enabled distinguishing 24 × 24 crystal arrays, compared to 22 × 22 with solid guides.
• Truncated center-of-gravity (TCoG) further enhanced pixel resolution at flood map edges and corners.
• Improved coordinate reconstruction accuracy and crystal flood map quality were observed.

Conclusions:

• Partly segmented light guides substantially enhance coordinate reconstruction accuracy at PET sensor module edges.
• This method can be combined with other techniques like TCoG for synergistic improvements in accuracy and flood map quality.