Change of MTF

Assessments of medical image was improved in accordance with development of medical imaging systems. One of them is edge method to determining MTF(Modulation Transfer Function) based on the Fujita method. Fujita was reduced sampling interval used slightly angulated slit to the direction of pixel array and composited finely sampled LSF to determine presampling MTF. In this study, we investigate the effect of sampling interval on the MTF under a digital imaging system by changing wire angle. The wire method was equivalent to the slit method except signal appearance. A Simens’s MAMMOMAT Inspiration with 0.085 × 0.085 mm2 pixel size made by amorphous selenium was used and 96 % accuracy on MTF in twice sampling interval compared with Fujita was obtained. However, three times of sampling interval showed 93 % accuracy on 50