CT 画像計測プログラムを用いた円形エッジ法における標的径とFOV に対するMTF 測定精度

抄録

Purpose: The purpose of this study was to evaluate the effects of target diameter and display-field of view (D-FOV) in modulation transfer function (MTF) by circular edge strategy using the computed tomography (CT) image measurement program “CTmeasure”. Methods: We calculated the MTF (MTF_edge) using the circular edge strategy applied to cylindrical phantom (200 mmφ) that inserted with cylinders have 10, 20, 30, and 40 mm diameters. The phantom images were reconstructed using filtered back projection method varied with D-FOV (240, 320, 400, and 500 mm). The study compared both MTF_edge and MTF_wire at MTF_50% and MTF_10% for target diameter and D-FOV, respectively. Results: The MTF_edge by the different of target diameter indicated in rough compatibility. However, MTF_edge of D-FOV diameters (320, 400, and 500 mm) decreased in the high frequency range. Conclusions: The circular edge strategy for MTF depended on the D-FOV, however, it was little dependent on target diameter using the CT image measurement program “CTmeasure”.