Investigation on basic imaging properties in medical radiography and its application (in Japanese)

The focus of this study was to investigate basic imaging properties of medical radiography and to develop a computer-aided diagnosis (CAD) scheme for automated detection and classification of interstitial infiltrates in chest radiographs. This dissertation included the following four topics: (1) comparison of two methods for accurate measurement of modulation transfer functions (MTFs) of screen-film systems with a slit and a square-wave test pattern; (2) evaluation of an asymmetric screen-film system for chest radiography; (3) investigation of basic imaging properties of a computed radiographic system with photostimulable phosphors; and (4) development of the CAD scheme for automated detection and classification of interstitial infiltrates with consideration of optical-density dependence on texture measures as an application of basic imaging properties. In this disseration, problems concerning resolution propertites of screen-film systems were discussed in detail. Moreover, effective methods to measure the presampling MTFs of a computed radiographic system as well as characteristic curves and noise properties were shown. Also, an application of the imaging properties to the development of the CAD scheme for interstitial infiltrates in chest radiographs was effective to improve the performance. This research clearly shows the importance of understanding basic imaging properties of analog and digital imaging systems in medical radiography.