Abstract: A method and apparatus for image processing on a radiation image which may be a conventional radiographic image on X-ray film or a radiation image which is stored in a stimulable phosphor and read out therefrom. The radiation image is scanned by a light beam or stimulating rays and an image signal is obtained by use of a photodetector. The image signal is subjected to a frequency processing by use of an unsharp masking process. The unsharp mask signal (Sus) is used for conducting an operation ofSorg+.beta.(Sorg-Sus)to obtain an image-processed signal S, wherein Sorg is a digital signal for each picture element of the scanned image and .beta. is a frequency emphasizing coefficient. The median of a group of digital signals in an unsharp mask of a predetermined size is employed.

Abstract: A method and apparatus for computed axial tomography (CAT) image reconstruction applicable to X-ray scanning of the human body. Successive series of calculations determine the values of a characteristic in defined segmented areas of an examination plane. A reduction in the time and equipment requirements for reconstruction calculations may thereby be effected.Images representative of the difference between the value of the characteristic at a reconstruction point and the average value of the characteristic in adjacent regions (.DELTA..mu.) may be calculated and displayed from measurements taken within a localized contiguous region of the examination plane. Radiation dose to patients and computation time in X-ray computerized axial tomography scanning systems is thus reduced. Differential displays of the type described may be adjusted to image boundaries, in which case they do not suffer from gray scale resolution problems which are typical of prior art displays.

Abstract: Measurement of magnetic field distributions is performed using a method based on the nuclear magnetic resonance (NMR) technique of Pourier imaging. By selecting objects which limit the spatial distribution of the NMR observable nuclei, images can be obtained which allow easy interpretation of the magnetic field distribution and facilitate rapid shimming of magnets. A method for providing a convenient display of field data is provided, as well as chemical shift imaging with correction for static field inhomogeneity. Results from these field plots are used as corrections for static field inhomogeniety when obtaining a chemical shift image. A method for localized spectral analysis from the chemical shift image is also provided.

Abstract: A method and apparatus for computed axial tomography (CAT) image reconstruction applicable to X-ray scanning of the human body. Successive series of calculations determine the values of a characteristic in defined segmented areas of an examination plane. A reduction in the time and equipment requirements for reconstruction calculations may thereby be effected.Images representative of the difference between the value of the characteristic at a reconstruction point and the average value of the characteristic in adjacent regions (.DELTA..mu.) may be calculated and displayed from measurements taken within a localized contiguous region of the examination plane. Radiation dose to patients and computation time in X-ray computerized axial tomography scanning systems is thus reduced. Differential displays of the type described may be adjusted to image boundaries, in which case they do not suffer from gray scale resolution problems which are typical of prior art displays.

Abstract: A method and apparatus for detecting the presence of caries in human teeth using visible luminescence. A region to be examined is excited with a beam of monochromatic light. The intensity of the visible light emitted from the region is measured at two predetermined wavelengths, one where the intensity dependence of the spectra is about the same for caries and noncaries and the other where the relative intensity increases significantly in the presence of caries. A signal corresponding to the difference in the two intensities is obtained and then displayed. By first determining the magnitude of the difference signal at a nondecayed region, any increases in the magnitude as other regions are probed indicate the presence of caries. The invention is based on the discovery that the visible luminescence spectra for decayed and nondecayed regions of a human tooth are substantially different and that the differences are such that visible luminescence from teeth can be used to detect the presence of caries.