Effect of noise levels of an edge image on determining the presampled modulation transfer function

摘要

The modulation transfer function (MTF) is widely used to describe the spatial resolution of x-ray imaging systems. Extensive works have been conducted to achieve accurate and precise measurement of MTF by using a slanted edge test device. The noise level of the slanted edge image is an important factor influencing the accuracy of MTF measurement. Thus in this work, a comparison study was made on the MTF measurement results obtained by using different curve fitting algorithms for ESF determination when analyzing the same image data with different noise levels. The results indicated that the averaged MTF measurement errors got increased with the decrease of the signal-to-noise ratio of the slanted edge images for all of the ESF processing algorithms. But for the same noisy slanted edge image, monotonic fitting algorithm outperformed Gaussian smoothing method or moving polynominal fitting method on MTF measurement.