Performance of a high-resolution depth encoding PET detector using barium sulfate reflector

Area of Science:

• Preclinical biomedical research
• Medical imaging technology
• Detector physics

Background:

• Small animal positron emission tomography (PET) is crucial for preclinical research.
• Current PET scanner performance is limited by detector capabilities.
• High spatial resolution and sensitivity require depth-encoding detectors.

Purpose of the Study:

• To evaluate the performance of a lutetium-yttrium oxyorthosilicate (LYSO) array using barium sulfate (BaSO4) as an inter-crystal reflector.
• To compare the BaSO4 reflector's performance against the commonly used enhanced specular reflector (ESR).
• To assess the potential of BaSO4 for developing advanced small animal PET scanners.

Main Methods:

• Fabricated and tested two dual-ended readout LYSO arrays (18x18 crystals, ~0.62x0.62x20 mm3).
• One array used BaSO4 powder as the inter-crystal reflector; the other used ESR.
• Measured flood histograms, energy resolution, depth of interaction (DOI) resolution, and timing resolution.

Main Results:

• The BaSO4 array exhibited significantly better flood histograms, clearly resolving all crystals.
• The ESR array showed less clear crystal resolution, particularly at the edges.
• Average energy resolution was similar (15.2% for BaSO4, 15.3% for ESR).
• DOI resolution was worse for BaSO4 (2.19 mm) compared to ESR (1.76 mm).
• Timing resolution was comparable (~1.6 ns) for both arrays.

Conclusions:

• The BaSO4 reflector offers superior crystal identification in dual-ended readout PET detectors compared to ESR.
• This new reflector enables the development of cost-effective small animal PET scanners with uniform high spatial resolution and sensitivity.