Granularity of X-ray Films and Random-dot Model

概要

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It is known that the Wiener spectrum of film graininess of X-ray films cannot be explained by the conventional random-dot model (RDM) in low spatial frequencies. It is considered that the cause of this phenomenon is due to the effects of grain aggregations in the developed emulsion. The RDM does not take account of the effects of grain aggregations. In order to analyze the effects of grain aggregations, the RDM is extended by K. Tanaka and S. Uchida. In this paper, measured Wiener spectra of film graininess of X-ray films are compared with the theoretical results of this extended random-dot model (ERMA) and the RDM. Density fluctuations of films are measured by means of the microdensitometer and Wiener spectra are calculated by Blackman-Tukey's method. Microphotographs of films are also compared with computer-generated random-dot patterns. By using these methods, it is concluded that the ERDM is more appropriate than the RDM in describing properties of Wiener spectra of film graininess of X-ray films in low spatial frequencies.
Medical Imaging and Information Sciencesの論文