Diagnostic imaging with Nuclear Medicine has been used in examination of various types of cerebrovascular diseases. Recently, measurement of glucose metabolism, oxygen consumption and neurotransmitter function has been developed using PET. Radiopharmaceuticals for SPECT have been formulated after its clinical usefulness has been determined by the PET. The new examination with SPECT includes rCBF and receptor imaging. Clinical SPECT and PET which gives information not only physiological but also biochemical function will eventually play a vital role in patients examination near future. Clinical application of these examinations has been presented in this paper.

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Recently, wavelet analysis is applied in various fields, in place of traditional transient analysis methods such as short time Fourier transform and Gabor transform. In this paper, we investigate the discriminant accuracy of the heterogenous region from the other normal area. In order to estimate the capability of discriminant, using the non-stationary random field as the image data, we carry out the simulation. The experiment results show the shift within a few pixel from the true boundary. To proceed these realized situations to the practical uses, some important problems to be settled are pointed out.

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We have developed a program to study the interaction between x-ray photons and a phantom, based on the Monte Carlo method. Using the program, we have calculated primary fraction varying the irradiation field size and the phantom thickness for the x-ray tube voltage of 100kV, and compared the calculated results with our experimental data. The results of the simulation and the experiment were in good agreement. We found that a primary fraction was given as a power function of the irradiation field within the limited range of the irradiation field, and that the scattered photon-angle distribution had a peak around 35°.

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The mandibular head has been extracted from a cine radiographic film digitized through a TV camera system, in order to trace its sagital motion during an opening and closing period of the mouth automatically. A model is given of subtraction based on the cine-film TV-input. An assumption of the additive property of radiographic images was used to compensate fluctuation of the illuminating light intensity by equalizing the average gray levels among the frames, as well as to estimate the background image by LIP, the least intensity projection. The background was estimated by peeping directly through the moving object at each pixel at an instant when the object did not contribute to the pixel intensity. This means that, for a sequence of images with both moving and unmoving objects, moving objects can be extracted by subtraction, even if it is impossible to take any image of the background separately. The developed method is called LIS, the least intensity subtraction. The mandibular head region was extracted by subsequent application of standard digital image recognition techniques including connected component extraction and erosion-dilation. The motion trajectory was obtained by tracing the top end point of that mandibular head region.

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