Estimation and validation of the frequency responses of a scanner system and an image reconstruction system in X-ray computed tomography

In computed tomography, factors that theoretically affect the modulation transfer function (MTF) in the region near the isocenter are the frequency responses of the scanner system (MTFS) and reconstruction processing (MTFA). Although MTFS and MTFA are performance indices that are not disclosed to the users, both can be estimated by the measured MTF with the use of theoretical formulas. In this study, we proposed two methods to obtain the MTFS and MTFA, and confirm their validity. The first method to obtain the MTFS and MTFA uses a theoretical formula and the measured MTF. Another method uses the measured MTF and the noise power spectrum. In both the methods, the MTFS and MTFA were obtained separately. By our proposed methods, performance indices that are not usually disclosed to the users can be known.

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