Positron range in combination with point-spread-function correction: an evaluation of different implementations for...

Area of Science:

• Nuclear Medicine
• Medical Imaging Physics

Background:

• Iterative image reconstruction in ¹²⁴I-PET imaging is crucial for accurate diagnosis.
• Positron range uncertainty and system-specific resolution characteristics affect image quality.
• Combining positron range correction (PRC) with point-spread-function (PSF) correction may enhance image fidelity.

Purpose of the Study:

• To evaluate the combined effect of PRC and PSF correction in iterative ¹²⁴I-PET image reconstruction.
• To compare different implementation methods of PRC (simplified vs. full) within iterative reconstruction algorithms.
• To assess the impact on contrast recovery and image noise.

Main Methods:

• ¹²⁴I positron range blurring kernels were generated using the GATE (GEANT4) framework in various materials.
• Iterative image reconstruction was performed using OSEM with and without PRC, and with PSF correction.
• Different PRC implementation strategies (simplified and full) were compared.
• Phantoms were used to evaluate contrast recovery and image noise on a Siemens mCT PET/CT system.

Main Results:

• Combining PRC and PSF significantly improved contrast recovery (up to 37% with full PRC, up to 19% with PSF+PRC).
• The benefit of PRC was more pronounced in low-density materials.
• Full PRC implementation was necessary for noise control, while simplified PRC offered faster convergence with comparable noise levels.
• PSF+PRC reconstructions showed improved contrast recovery with reduced image noise compared to stand-alone corrections.

Conclusions:

• The combination of PSF and PRC offers superior contrast recovery and noise reduction in ¹²⁴I-PET imaging.
• Full PRC implementation is essential for managing image noise in OSEM-PRC reconstructions.
• Simplified PRC implementation can be effectively utilized when combined with PSF correction to reduce overall reconstruction time.