等解像度画像を用いたＣＴの性能評価

Abstract

A method of evaluating the performance of computed tomography (CT) with equivalent resolution images was investigated. Generally, in performance evaluations of CT, the resolution property is measured by the wire method, and the noise property is measured from noise images of a cylindrical water phantom. The signal-to-noise ratio (SNR) is then calculated for the integrated evaluation. Our proposed method enabled perceptual integrated evaluation by using equivalent resolution images created with frequency processing. The frequency-processing factor was calculated from the ratio of the modulation transfer factors of two models of CT, and the image of one of the two was processed by the factor. Because these processed images have resolution equivalent to images of the other CT, the perceptual evaluation with noise images becomes effective. In this investigation, images of a water phantom and a middle contrast resolution phantom were employed. Perceptual comparison of the amount of noise with equivalent resolution images could be performed easily, and effective performance evaluation was achieved. Therefore, our proposed method is useful for noise property and performance evaluation of CT.