A stationary hemispherical SPECT imager for three-dimensional brain imaging

Area of Science:

• Medical Imaging
• Nuclear Medicine
• Biomedical Engineering

Background:

• Single Photon Emission Computed Tomography (SPECT) is crucial for brain imaging.
• Traditional SPECT systems face limitations in spatial resolution and sensitivity.
• Coded aperture imaging offers potential for improved SPECT system design.

Purpose of the Study:

• To design and evaluate a stationary, hemispherical-coded aperture SPECT system for 3D brain imaging.
• To characterize the system's spatial resolution and sensitivity.
• To assess the impact of coded aperture multiplexing on data quality.

Main Methods:

• A hemispherical multiple-pinhole coded aperture was integrated with 20 digital gamma cameras.
• Two laboratory versions of the system were constructed and tested.
• Image reconstruction algorithms were applied to acquired projection data.
• Performance metrics including spatial resolution and sensitivity were measured.
• An ideal-observer model was used to quantify data degradation.

Main Results:

• The system achieved a reconstructed field of view of 100 x 100 x 50 mm.
• Spatial resolution was measured at 4.8 mm FWHM at the center of the field of view.
• System sensitivity was determined to be 36 counts per second per microCurie (cps/µCi).
• Multiplexed data showed a 21% degradation compared to non-multiplexed data.

Conclusions:

• The developed stationary, hemispherical-coded aperture SPECT system demonstrates potential for 3D brain imaging.
• The system achieves specific spatial resolution and sensitivity benchmarks.
• Data degradation due to multiplexing necessitates consideration for effective sensitivity calculations, yielding 79% of measured sensitivity.