Optimization, evaluation and calibration of a cross-strip DOI detector

Area of Science:

• Medical Imaging Physics
• Detector Technology
• Nuclear Medicine

Background:

• High-resolution Positron Emission Tomography and Magnetic Resonance (PET/MR) imaging requires advanced detector capabilities.
• Depth of Interaction (DOI) determination is critical for improving PET image reconstruction accuracy.
• Silicon Photomultiplier (SiPM) detectors offer potential for compact and high-performance PET systems.

Purpose of the Study:

• To evaluate a dual-sided readout SiPM detector for its Depth of Interaction (DOI) capability.
• To assess the detector's suitability for high-resolution PET/MR imaging applications.
• To compare the performance of different scintillator arrays and calibration methods for DOI resolution.

Main Methods:

• Evaluation of two pixelated Lutetium-based Scintillator (LSO) arrays (12x12 pixels, 1.60 mm pitch) with different lengths and reflectors (Vikuiti ESR and Lumirror E60).
• Implementation and comparison of linear and nonlinear calibration methods using intrinsic scintillator radiation against a conventional method with a collimated beam.
• Measurement of energy resolution, DOI resolution, and coincidence resolving time.

Main Results:

• An improved energy resolution from 22.6% to 15.5% was achieved with the E60 reflector array using nonlinear light collection correction.
• Average FWHM DOI resolutions of 2.96 mm (ESR) and 1.83 mm (E60) were obtained.
• Linear and nonlinear calibration methods showed small deviations from the conventional method (0.32-0.67 mm), with the linear method being simpler and applicable to assembled systems.

Conclusions:

• The dual-sided readout SiPM detector demonstrates promising DOI capability for high-resolution PET/MR imaging.
• The choice of reflector and calibration method significantly impacts energy and DOI resolution.
• The developed linear calibration method offers a practical and accurate approach for DOI determination in assembled detector systems.