Resolution recovery in pinhole SPECT based on multi-ray projections: a phantom study

Area of Science:

• Medical Imaging
• Nuclear Medicine
• Image Reconstruction

Background:

• Pinhole apertures in SPECT imaging often suffer from low sensitivity.
• Increasing aperture size improves sensitivity but degrades spatial resolution.
• A better resolution-sensitivity trade-off is needed for improved SPECT imaging.

Purpose of the Study:

• To explore an iterative reconstruction algorithm using multi-ray projections to model the pinhole aperture.
• To improve the resolution-sensitivity trade-off in SPECT imaging.

Main Methods:

• Validated a new iterative reconstruction algorithm with simulated data and phantom experiments.
• Investigated two approaches: modeling the pinhole aperture in forward/back projectors and a dual matrix implementation.
• Quantified systematic error, full-width at half-maximum (FWHM), and statistical error.

Main Results:

• Modeling the pinhole aperture during iterative reconstruction decreased systematic error, FWHM, and statistical error.
• Achieved smaller systematic errors and FWHM for a fixed statistical error by modeling the pinhole opening.
• The dual matrix implementation yielded results comparable to modeling in both projectors.

Conclusions:

• The multi-ray method enhances resolution recovery in pinhole SPECT.
• This approach offers a superior trade-off between spatial resolution and noise.
• It provides better image quality compared to reconstructions that do not model the pinhole aperture.