Abstract: An NMR imaging method using a rotating field gradient is disclosed in which transverse magnetization is prepared in a portion of an object to be inspected, by the 90.degree.-180.degree. RF pulse excitation, a rotating field gradient is generated to perform a sampling operation for an output signal in a state that the position of signal in a phase space is revolved, the intensity or rotational speed of the rotating field gradient is varied stepwise or continuously to obtain data arranged on concentric circles or a spiral in the phase space, and the data thus obtained undergoes Fourier transformation in each of a plurality of radial directions or two-dimensional Fourier transformation, to form an image of spin distribution.

Abstract: The present invention is an imaging method using three-dimensional NMR to which an echo-planar method is applied. After excitation of nuclear spins, the gradient magnetic field Gx for phase-encoding is applied and there is repeated a sequence of measuring and obtaining an echo train of spin-echoes with a constant gradient magnetic field Gx and a periodically-inverted gradient magnetic field Gy, as varying the amount of encoding, so as to obtain the three-dimensional imaging by the Fourier-conversion. Moreover, after the selective excitation of spins within an X-Y surface, a 180.degree. radio frequency pulse is applied. As varying the time difference .tau..sub..epsilon. between the interval from the excitation until the application of the 180.degree. radio frequency pulse and the interval from the application thereof until a peak of a first echo of an echo train, three-dimensional imaging is carried out with a chemical shift axis as one axis by repeating the sequence and accomplishing Fourier-conversion with .

Abstract: An NMR imaging method which provides a three-dimensional image representative of the two-dimensional distribution of nuclear spin species resolved by chemical shift or the local spectra resolved by two-dimensional location. After the excitation of nuclear spins and the phase-encoding by application of a field gradient G.sub.y, a periodically inverting field gradient G.sub.x is generated to yield a continuous echo train. The echo train is sampled and separated into data of odd-numbered echoes and data of even-numbered echoes which data are in turn reconstructed into two-dimensional data arrays, respectively. The data thus reconstructed are three-dimensional Fourier-transformed.

Abstract: A method of measuring a static magnetic field distribution in a nuclear magnetic resonance (NMR) inspection system which comprises magnetic field generator for producing a static magnetic field, inclination or gradient magnetic fields and a high-frequency magnetic field, a signal detector for sensing nuclear magnetic resonance signals from an inspection sample, a computer for processing output signals from the signal detector and an output device for providing a computational result of the computer, wherein a time interval t.sub.1 from the center of a 90.degree.-pulse high-frequency magnetic field to the center of a 180.degree.-pulse high-frequency magnetic field is made different by a time difference t.sub.0 from a time interval t.sub.2 from the center of the 180.degree.-pulse high-frequency magnetic field to a peak of a spin echo, so that static magnetic field distribution is calculated based on the computer output which corresponds to the difference of the two time intervals.

Abstract: An NMR imaging apparatus and method for direct Fourier imaging. This apparatus includes a static magnetic field generator, gradient magnetic field generators, high-frequency magnetic field generator, signal detecting detector for detecting a nuclear magnetic resonance signal from a body to be inspected, a computer for performing an arithmetic operation for the detected signal to obtain the nuclear magnetic resonance intensity distribution in the to-be-inspected body from measured values of the nuclear magnetic resonance intensity distribution at various points on a rectangular coordinate system in the Fourier space, and memories used for correction.

Abstract: An NMR imaging apparatus for reconstructing a cross section of a body to be inspected, by the projection-reconstruction method. That is, an apparatus for forming the above cross section in such a manner that the nuclear magnetic resonance is caused by the to-be-inspected body in the resulting magnetic field of a static magnetic field and a rotatable gradient field, a projection of the to-be-inspected body is detected at each rotational positions of the gradient field, and the cross section is reconstructed using the above projection. The apparatus comprises memories for previously storing therein data indicating the distorsion of magnetic field such as the non-uniformity of the static magnetic field and the non-linearity of the gradient field, in order to perform the coordinate calculation in the back projection, using the data stored in the memories.

Abstract: In an imaging apparatus using nuclear magnetic resonance which includes apparatus for generating a static magnetic field, a linear gradient magnetic field and a radio frequency magnetic field, respectively, signal detection device for detecting the nuclear magnetic resonant signal from an object to be inspected, a computer for calculating from the detection signal an image and output device for displaying the result of calculation by the computer, the improvement wherein the size of the object to be inspected is detected by use of ultrasonic wave or light beams and a signal indicative of the detected size of the object is applied to the linear gradient magnetic field generation apparatus so as to control the intensity of the linear gradient magnetic field.

Abstract: A radiation-image photographing apparatus comprises a radiation source, a radiation detector disposed in opposition to the radiation source for detecting radiation through an object to be examined and to generate an electrical signal proportional to the amount of incident radiation, a scanning device for changing the relative, positional relationship between the radiation source and the radiation detector, an analog-to-digital converter for converting the output signal from the radiation detector to a digital quantity, a memory for storing the digital signal, an arithmetic unit, and a display unit.

Abstract: An imaging apparatus using nuclear magnetic resonance is disclosed in which both an image corresponding to the projection of a nuclear spin distribution in a to-be-inspected object on a two-dimensional plane and a display mark indicating a desired measuring position are displayed on a display face of a display device such as a CRT display, the display mark is freely moved on the display face to be set at a desired position on the display face, and magnetic field generating means for generating a static magnetic field, linear gradient field, or radio frequency magnetic field is controlled on the basis of the desired position of the display mark to obtain an image of that cross section of the object which is located at a position indicated by the display mark.

Abstract: An electromagnet having a current detecting device for detecting the current flowing through an electromagnet exciting coil, the output of which is utilized to control the power supplied to the coil to stabilize the current flowing through the coil; the electromagnet further including a separate power supply to supply current to the current detecting device which supplies current to the current detecting device when the electromagnet is not on working.

Abstract: A tomographic imaging system is disclosed in which the quantity of absorption or transmittance of a transmissive radiation by or through a certain tomographic cross-section of an object under consideration is detected and the distribution of radiation absorption or transmittance in the cross-section is reconstructed through a convolution operation. A weighting function used in the convolution operation is prepared with a predetermined one of its positive orders the value of which is an integration of the weighting function from the predetermined positive order to positive infinity and a predetermined one of its negative orders the value of which is in integration of the weighting function from the predetermined negative order to negative infinity.

Abstract: In a system in which the tomographic image of an object under investigation is produced on the basis of the amount of absorption of radiation by the object when a source of radiation and a plurality of radiation sensitive detectors with the object interposed therebetween are rotated around the object, the output signal from at least one of the plural detectors is used to correct the radiation absorption amount. Another selected one of the plural detectors may be used for checking whether the object is positioned within a useful detection view.