Reducing multiplexing artifacts in multi-pinhole SPECT with a stacked silicon-germanium system: a simulation study

Area of Science:

• Medical Imaging
• Nuclear Medicine
• Spectroscopy

Background:

• Multi-pinhole collimators in single photon emission computed tomography (SPECT) enhance sensitivity but can cause projection overlap (multiplexing), leading to image artifacts.
• Germanium (Ge) detectors are commonly used in SPECT, but their projections can exhibit significant multiplexing.

Purpose of the Study:

• To investigate if a stacked-detector configuration using both germanium (Ge) and silicon (Si) detectors can mitigate image artifacts in SPECT.
• To evaluate the impact of low-multiplexing Si projections on reducing artifacts from highly-multiplexed Ge projections.

Main Methods:

• Simulations were performed to develop a reconstruction method combining Si and Ge projections.
• Digital phantoms and varying pinhole configurations were used to simulate different levels of projection multiplexing.
• Reconstructed images were quantitatively assessed using normalized mean-square error and normalized standard deviation.
• Qualitative assessment of artifacts was performed using the differential point response function.

Main Results:

• The addition of Si projections, which exhibit minimal multiplexing, effectively reduced image artifacts in SPECT reconstructions.
• Both quantitative and qualitative analyses demonstrated a significant improvement in image quality when Si data was incorporated.
• The proposed method successfully mitigated artifacts arising from highly-multiplexed Ge projections.

Conclusions:

• A stacked-detector approach with Ge and Si detectors offers a viable strategy to improve image quality in SPECT.
• Utilizing low-multiplexing Si projections alongside high-multiplexing Ge projections is an effective method for artifact reduction in SPECT imaging.