An Improved Method of Measuring Spatial Resolution of the Computed Tomography from ESF based on CT phantom images

摘要

Spatial resolution is an important feature of the computed tomography (CT) imaging system, which is the ability of an image to convey details and distinguish between small objects that are close together. In this paper, a simple developed methodology for measuring the spatial resolution of CT images is implemented using phantom images. The present study offers an alternative methodology to the measurement of the spatial resolution of CT machine which is based on the calculation of the full width at half maximum (FWHM) of the line spread function (LSF) acquired from a function called the edge spread function (ESF). The ESFs data were constructed from the CT image obtained by scanning phantom made of silicone rubber shaped as a cylindrical containing different material. The ESF curves were obtained by a direct fit of a mathematical expression of the ESF profile using MATLAB (R2015b) to the ESF data acquired at the interface between the different materials within the experiment phantom. The proposed methodology can be implemented using signal data from the reconstructed CT image and is not sensitive to the noise introduced by differentiating the ESF to produce the LSF as noted in the previous measurement. In addition, the proposed methodology provides a practical measurement of CT machine spatial resolution.