Initial Performance of a Prototype Small Animal PET Scanner Consisting of Long Semi-Monolithic Scintillator Detectors

Area of Science:

• Medical Imaging
• Nuclear Instrumentation
• Materials Science

Background:

• Monolithic scintillator detectors offer depth-of-interaction (DOI) capabilities but suffer from edge effects.
• Semi-monolithic detectors combine DOI encoding with reduced edge effects, enhancing detector performance.
• Small animal Positron Emission Tomography (PET) requires high spatial resolution and sensitivity for preclinical research.

Purpose of the Study:

• To investigate the performance of long semi-monolithic scintillator detectors for small animal PET scanners.
• To evaluate the spatial resolution, sensitivity, and imaging capabilities of a PET scanner utilizing these detectors.
• To demonstrate a position calibration method suitable for semi-monolithic detector systems.

Main Methods:

• Manufactured two semi-monolithic detectors using LYSO slabs with ESR or BaSO4 reflectors.
• Built a prototype PET scanner with two detectors for spatial resolution measurements using a 22Na point source.
• Simulated a full-ring PET scanner with 20 detectors using GATE software to assess sensitivity and imaging performance.
• Developed and applied a position calibration method for improved response uniformity.

Main Results:

• Achieved spatial resolution better than 0.65 mm in the prototype scanner using point spread function (PSF) modeling.
• Simulations showed a peak sensitivity of 5.45% for a full-ring scanner.
• Resolved 0.75 mm diameter rods in phantom images reconstructed with PSF modeling.
• The proposed calibration method effectively addressed non-uniform responses.

Conclusions:

• Long semi-monolithic scintillator detectors are a promising technology for small animal PET systems.
• These detectors enable sub-millimeter uniform spatial resolution and good sensitivity.
• The developed technology offers a potentially cost-effective solution for advanced preclinical imaging.