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4418419 Dental tomography apparatus
New Patents
xiv
A tomographic image of X-ray tested tissue of body is reconstructed by calculating X-ray absorption coefficients of picture elements constituting a tomographic plane in reference to measured values produced by the first and second projectional distributions of X-ray produced by projecting X-ray. Accordingly, it becomes possible to reconstruct a clear tomographic image of a moving X-ray tested tissue and to make an X-ray exposure level very low by extremely shortening the time of the reconstruction of computed tomographic image. Moreover, a resolving power of measuring is substantially improved, resulting in that an accuracy of reconstructing the tomographic image may also be improved.
that the contacts whose position corresponds to the shape of the dentition are actuated. Therefrom, the contour of the dentition is determined by an arithmetic unit which supplies the control signals for the drive motors.
4418387 METHOD OF RECONSTRUCTING A COMPUTED TOMOGRAPHIC IMAGE FROM A SINGLE X-RAY PROJECTION Shoichiro Yamaguchi, Fujio Kobayashi, Tokyo, Japan assigned to The President of Tokyo Institute of Technology
4418419 DENTAL TOMOGRAPHY APPARATUS Peter Schreiber, Eberhard Steenfadt, Gerard P M Bergman, Rellingen, Federal Republic Of Germany assigned to U S Philips Corporation
l3a
A dental tomography apparatus comprises three drive motors for displacing the film and the Xray source in two mutually perpendicular directions in a horizontal plane and for pivoting the carrier which connects the film and the X-ray source. The control signals for the motor drives are derived from the contour of the dentition by means of a plate which is covered by contacts on which the patient exerts a pressure by biting, so
A method of reconstructing a computed tomographic image comprising projecting Xrays through material to be tested at a plurality of spaced positions, and measuring the X-ray density values of the X-rays projected through the material along the distribution of projected X-rays. The spaced positions at which the X-ray density values are measured are selected such that the tomographic plane of the material to be reconstructed is represented by a pseudotomographic plane comprised of an array of n rows of m columns of picture elements, each having a single piece of X-ray density information, and such that each X-ray beam passes through the lower left corner of a corresponding picture element. The X-ray absorption coefficient for each picture element is calculated from the measured values of X-ray density, and the computed tomographic image is reconstructed by positioning picture elements having the computed X-ray absorption coefficients in an array corresponding to the array in the pseudotomographic plane.
For information about PATSEARCH@
Pergamon International Information Corporation 1340 Old Chain Bridge Road McLean, Virginia 22101 USA Telephone (703) 442-0900 Telex: 90-1811
Pergamon InfoLine Limited 12 Vandy Street London EC2A 2DE England Telephone (01) 377-4650 Telex: 8814614
Pergamon Press Canada Ltd 150 Consumers Road, Suite 104 Willowdale, Ontario Canada M2J lP9 Telephone (416) 497-8337
xiv
A tomographic image of X-ray tested tissue of body is reconstructed by calculating X-ray absorption coefficients of picture elements constituting a tomographic plane in reference to measured values produced by the first and second projectional distributions of X-ray produced by projecting X-ray. Accordingly, it becomes possible to reconstruct a clear tomographic image of a moving X-ray tested tissue and to make an X-ray exposure level very low by extremely shortening the time of the reconstruction of computed tomographic image. Moreover, a resolving power of measuring is substantially improved, resulting in that an accuracy of reconstructing the tomographic image may also be improved.
that the contacts whose position corresponds to the shape of the dentition are actuated. Therefrom, the contour of the dentition is determined by an arithmetic unit which supplies the control signals for the drive motors.
4418387 METHOD OF RECONSTRUCTING A COMPUTED TOMOGRAPHIC IMAGE FROM A SINGLE X-RAY PROJECTION Shoichiro Yamaguchi, Fujio Kobayashi, Tokyo, Japan assigned to The President of Tokyo Institute of Technology
4418419 DENTAL TOMOGRAPHY APPARATUS Peter Schreiber, Eberhard Steenfadt, Gerard P M Bergman, Rellingen, Federal Republic Of Germany assigned to U S Philips Corporation
l3a
A dental tomography apparatus comprises three drive motors for displacing the film and the Xray source in two mutually perpendicular directions in a horizontal plane and for pivoting the carrier which connects the film and the X-ray source. The control signals for the motor drives are derived from the contour of the dentition by means of a plate which is covered by contacts on which the patient exerts a pressure by biting, so
A method of reconstructing a computed tomographic image comprising projecting Xrays through material to be tested at a plurality of spaced positions, and measuring the X-ray density values of the X-rays projected through the material along the distribution of projected X-rays. The spaced positions at which the X-ray density values are measured are selected such that the tomographic plane of the material to be reconstructed is represented by a pseudotomographic plane comprised of an array of n rows of m columns of picture elements, each having a single piece of X-ray density information, and such that each X-ray beam passes through the lower left corner of a corresponding picture element. The X-ray absorption coefficient for each picture element is calculated from the measured values of X-ray density, and the computed tomographic image is reconstructed by positioning picture elements having the computed X-ray absorption coefficients in an array corresponding to the array in the pseudotomographic plane.
For information about PATSEARCH@
Pergamon International Information Corporation 1340 Old Chain Bridge Road McLean, Virginia 22101 USA Telephone (703) 442-0900 Telex: 90-1811
Pergamon InfoLine Limited 12 Vandy Street London EC2A 2DE England Telephone (01) 377-4650 Telex: 8814614
Pergamon Press Canada Ltd 150 Consumers Road, Suite 104 Willowdale, Ontario Canada M2J lP9 Telephone (416) 497-8337