Iterative reconstruction of SiPM light response functions in a square-shaped compact gamma camera

Area of Science:

• Medical Imaging
• Nuclear Instrumentation
• Computational Physics

Background:

• Compact gamma cameras are vital for small animal imaging, cancer diagnostics, and surgical guidance.
• Accurate spatial response of silicon photomultipliers (SiPMs) is essential for advanced statistical reconstruction methods, outperforming traditional centroid techniques.

Purpose of the Study:

• To develop and validate an iterative method for parameterizing the spatial response functions of SiPMs in compact gamma cameras.
• To assess the impact of this parameterization on image reconstruction accuracy using both Monte Carlo simulations and experimental data.

Main Methods:

• Utilized Monte Carlo simulations and experimental data from a gamma camera prototype with a LYSO crystal and an 8x8 SiPM array.
• Employed an iterative approach to parameterize SiPM spatial responses with axially symmetric functions from flood field irradiation data.
• Reconstructed images using the maximum likelihood method with the derived response functions.

Main Results:

• The iterative method successfully parameterized the spatial response functions of all SiPMs.
• Simulations showed minor image distortions, with average position differences not exceeding 0.2 mm centrally and 0.4 mm peripherally.
• Experimental validation confirmed a similar low level of image distortions with the camera prototype.

Conclusions:

• The iterative parameterization of SiPM spatial response functions is effective for compact gamma cameras.
• This method significantly improves image reconstruction accuracy, minimizing positional distortions for enhanced diagnostic capabilities.
• The findings support the use of statistical reconstruction methods with accurately characterized spatial responses in gamma imaging.