Recently, remarkable attention is focused on the low coherence interferometry in order to realize visualization of thin sections of biological tissue. In our experiment, a specific low coherence interferometer was developed to evaluate quantitatively the spatial resolution of the detected image of a fine test pattern. It was then found that the resolution was nearly 10μm along the depth and<10μm in the cross section. Moreover, in actual optical CT, it is necessary to determine as precisely the dimensions of a biological tissue as possible. To do this, the refractive index n and thickness t of the biological tissue should be measured simultaneously. We proposed and developed a new technique for simultaneous measurement of n and t based on the low coherence interferometry. The detail will be described in this paper. Recent activities of there methods for optical CT are also presented.

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In the previous paper, we proposed a psychophysical RMS granularity σ_p for the evaluation of radiographic mottle [J. Photogr. Sci.,43,103 (1995)]. Moreover, we found that the density dependence of psychophysical Wiener spectrum W_p (ν)at the frequency near 2.0mm^-1 has a good correlation with that ofσp² [J. Photogr. Sci.,44,89(1996)].
In this paper, we supported the vahdity of σ_p by comparing with the subjective rating result for additional three medical X-ray films having the different characteristics, and we found more accurate equivalent spatial frequency between W_p(ν)and σ_p². The equivalent frequencies were 2.0∼2.2mm^-1 on 8000 lm⋅m^-2 viewer and 1.6mm^-1 on 1500 lm⋅m^-2 viewer.

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The aim of this study was to review the basic points in the LSF measurements of the intensifying screen by MIC system(Microscope-Image intensifier-Charged coupled devicesystem). The results obtained were as follows:
There was a significant difference between the LSF calculated from the intensifying screen film combination and LSF obtained directly from the MIC system. The LSF obtained from the MIC system was much sharper. In the case of LSF measured for the combination of the intensifying screen and the film, multiple light reflection of the fluorescence occurred in the space between the intensifying screen and the emulsion layer of the film, and it is deduced from experiments that this contributed greatly to the impairment of sharpness. Controlling this phenomenon enables development of new system that will satisfy the opposing factors of high sensitivity and sharpness of the intensifying screen film combination.

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We have been developing a computer-aided diagnosis(CAD) system for detecting clustered microcalcifications and masses on digital mammograms. In our recent study, we found that the automated breast-region- extraction algorithm used in this CAD system was not accurate sometimes when we increased the database and tested many mammograms. This algorithm was based on the breast-border determination technique. The purpose of this study is to modify and improve this technique and also to test it by increasing image data. In our revised technique, the weight of the location information of breast border and the differentiation of the image density profile were included, and the location of breast region on the film and the number of breasts imaged on the same film were also considered. The new technique was succeeded in the extraction of the breast region in 728 cases(98.8%) out of 737mammograms obtained from 8 different facilities.

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