Co-registered image quality comparison in hybrid iterative reconstruction techniques: SAFIRE and SafeCT

Abstract

Iterative reconstruction techniques (IRTs) are used to reduce the radiation dose significantly and suppress the noise in computed tomography (CT) imaging. However, the image from IRTs is unacceptable to the human visual system due to the presence of outlier and non-Gaussian noise structure. The conventional noise measurements, such as mean and standard deviation, are limited to provide the information of noise characteristics of an image comprehensively when the undesirable noise structure happens on the image. In this study, the images reconstructed by using Weighted filtered back-projection (WFBP) and image-based IRTs (SAFIRE and SafeCT) were compared in terms of conventional noise statistics, high-order noise statistics, modulation transfer function (MTF), and slice sensitivity profile (SSP) with different levels of radiation dose. The results showed that the noise characteristics, which were considered with conventional and high-order noise statistics, and spatial resolution characteristics were different for the IRTs, reconstruction parameters, and levels of radiation dose. This study can contribute to the optimization of image quality from IRT with the reduction of radiation dose and development of IRT which overcomes the issue caused by undesirable noise structures.