Comparison between Physical Image Quality asMeasured by a Newly Developed Phantom Dedicated for Digital Mammography QC and That by European Guidelines Methods

摘要

A quality control system for digital mammography consisting of a phantom for daily constancy test and software for image analysis and data management has been developed. The purpose of this study was to verify the measurement accuracy of the phantom and software, which was carried out by comparison of the result obtained from the method in accordance with European Guidelines for the following image characteristics; 1) Contrast to Noise Ratio (CNR) 2) Geometric distortion 3) Modulation Transfer Function (MTF) 4) Homogeneity 5) Missed tissue at chest wall side and 6) Threshold contrast visibility. In CNR and MTF, relative differences of 10% and 20% respectively were confirmed though, they were due to the difference in samples used for each measurement and in measurement position, and then those differences were identified as being no problem for the constancy test.