Simulation Analysis on the Performance of a Circular-Edge Technique in Measurements of the Modulation Transfer Function

Abstract

The modulation transfer function (MTF) plays an important role in characterizing medical imaging systems. For such characterization, the circular-edge technique has become a prevalent task-based methodology. When determining the MTF with complicated task-based measurements, error factors must be well understood to properly interpret the results. In this context, the aim of this work was to study the changes in measurement performance in the analysis of the MTF using a circular edge. To eliminate the systematic error related to the measurement and suitably manage the error factors, images were generated by Monte Carlo simulation. Further, a performance comparison with the conventional method was conducted; in addition, the influence of the edge size and contrast and the setting error of the center coordinates were investigated. The difference from the true value and the standard deviation relative to the average value were applied to the index as the accuracy and precision, respectively. The results demonstrated that the smaller the circular object used and the lower the contrast, the grater the deterioration in the measurement performance. Furthermore, this study clarified the underestimating of the MTF in proportion to the square of the distance with respect to the setting error of the center position, which is important for the synthesis of the edge profile. Evaluations in the backgrounds wherein there are multiple factors affecting the results are complex, and the system users must properly judge the validity of the characterization results. These findings provide meaningful insight in the context of MTF measurement techniques.

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

“…For this work, analysis target images were generated using Electron Gamma Shower version 5. 22,23 This simulation was applied to eliminate potential factors other than shape distortion of a circular edge in the MTF measurement. In addition, random noise (i.e., uncorrelated x-ray quantum noise) was introduced, and the shape of the edge object was precisely adjusted within the simulation.…”