Characterization of spatial resolution through Fourier ring correlation in digital neutron radiography

Abstract

Spatial resolution is a very important parameter in any imaging system, from medical to industrial even in astronomy and it should be considered every time images are analysed or even before processing. The aim of this work was to characterize spatial resolution in digital neutron radiography using the proposed method of Fourier Ring Correlation (FRC), a method which was mainly developed for cryo-microscopy imaging. This proposed method was adopted in this work for determination of spatial resolution. The Modulation Transfer Function (MTF) also known as Spatial Frequency Response (SFR) is the method used in digital neutron radiography to determine the spatial resolution of an image. The reason for adopting the FRC method was to determine if this proposed method is suitable to be applied in digital neutron radiography to find the spatial resolution of images. The current method used in neutron radiography, which is the standard method MTF/SFR, uses an edge analysis which has been observed to be a complex technique to find the spatial resolution. The results were achieved using MATLAB. Different MATLAB functions were used for FRC and MTF/SFR. The FRC results were compared with that of the standard method in neutron radiography MTF/SFR. This comparisons were made at different Object to Detector Distance (ODD). The percentage differences of FRC and MTF/SFR at different ODD's were 88.24%, 3.57%, 3.70% and 26.67%. The results yielded a higher percentage difference than expected, especially the 88.24% is quite high. FRC can be applied in neutron radiography to determine the spatial resolution as the results from different ODD's have shown a percentage differences less than 5%. The conclusion from this study is that FRC method can be used to determine spatial resolution in neutron radiography but filtering needs to be done as part of image analysis. Although it is recommended, in future studies, apodization and filtering methods should be taken into consideration for better spatial resolution.