Analysis of the precision of modulation transfer function measurements with a circular edge: influence of object circularity.

Abstract

To measure the modulation transfer function (MTF) using a circular edge, we generate a synthesized edge spread function from multiple profiles radiating from the center, assuming that the circular object is perfectly round. Therefore, this study aimed to quantify the influence of the shape change of the circular edge on the measurement precision of the MTF. To examine this relationship, we generated simulated images with intentionally distorted circular edges and analyzed the correlation between circularity and the calculated MTF. This simulation was designed to replicate the MTF properties of an actual computed tomography image and was applied to isolate the effect of shape distortion on MTF measurements. MTF measurements were conducted on 11 different circularity images to determine the spatial frequencies at which the MTF values are 50% () and 10% (), and the error rates to the true value were calculated. Our findings revealed a correlation between circularity and the measured MTF value. Specifically, an 1% decrease in circularity from the perfect circle condition resulted in an approximately change in . This decrease in MTF values was attributed to the presence of rectangular spatial blurring, which occurs when a distorted circular image is used to generate the synthetic edge profile. This study provided insights into the influence of the shape changes in the circular edge on MTF measurements. The present findings contribute to a better understanding of the evaluation results and measurement errors when describing the image quality characteristics modalities using the circular edge technique.