Optimizing Image Reconstruction Parameters in Time of Flight PET/CT Imaging: a Phantom Study

Purpose- The aim of this study was to determine optimal reconstruction parameters in relation to the image quality and quantitative accuracy for advanced reconstruction algorithms by phantom study. Methods- A house-made image quality phantom, including 6 cylindrical inserts, was filled with an 18F-FDG solution with a 4:1 radioactivity ratio compared to the background. All emission data was acquired in 3D list-mode. The PET data reconstructed with TOF only and TOF+PSF algorithms. The reconstructed images were post-filtered with Gaussian filters with varying FWHM (0 to 10 mm with 0.5 mm increment). All images were reconstructed with different product of iterations and subsets (It×SS) ranging from 3 to 144. Optimal image reconstruction parameters were determined by calculating quantitative parameters including noise, signal to noise ratio (SNR), and recovery coefficient (RC). Results- Our results showed that Gaussian filtering with FWHM greater than 5 mm for TOF and greater than 3.5 mm for TOF+PSF algorithms led to an acceptable clinical noise level (