Surgery – Truss – Pad
Patent
1990-07-27
1993-08-24
Cohen, Lee S.
Surgery
Truss
Pad
A61B 602
Patent
active
052379981
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a national phase of PCT/FR 89/00594 filed Nov. 17, 1989 and based upon French national application 88 15483 of Nov. 18, 1988 under the International Convention.
FIELD OF THE INVENTION
The present invention relates to a method of correlating three-dimensional images of human organs and to a device for the implementation of the method.
BACKGROUND OF THE INVENTION
Various methods exist for imaging the shape of an internal and external human organ.
The first consists in using an impression paste of greater or lesser elasticity and in reconstructing the part by plaster casting in order to obtain the complete reproduction of said organ.
A second method described by Moshabac in 1977 (U.S. Pat. No. 4,182,312) and then by Becker (U.S. Pat. No. 4,411,626) consists in micro-tracing the surface being studied and, where appropriate, reconstructing it using a micro-profiler.
A third method consists in taking an X-ray or tomodensitometric reading, then in repositioning each section as a function of the position of the X-ray analysis receivers and sensors.
A fourth method consists in using the NMR principle (nuclear magnetic resonance) or MRI principle (MR imaging), known methods which have been widely described and permit reconstruction of the part using a numerically controlled micro-profiler (Information dentaire, September 1988).
Finally, a new method described in a series of previous documents uses stereoscopic methods (Rooder) or moire effect methods (Duret) and makes it possible to take a three-dimensional reading of the objects photographed.
This last method, introduced very recently in dentistry, makes it possible to form an image, but does not afford the possibility of correlating various images in order to obtain an overall view of the part which is the subject of the study.
In particular, the only means used in order to correlate views presupposes the fixing of the object analyzed and of the camera in known positions of the computing and analysis center. Thus, it is relatively common nowadays to effect a rotation of the object facing the analysis camera. Such a technique is difficult to implement in the case of the imaging of a part of the jaw of a subject, in the case of dentistry.
OBJECTS OF THE INVENTION
The object of the present invention is to provide a method of and a device for the correlation of a set of three-dimensional dental or medical views of an object or to correlate several objects which may themselves have formed the subject of a correlation, without knowing a priori the position of the object and of the camera at the computer level.
SUMMARY OF THE INVENTION
To this end, the method to which the invention relates consists in affixing or locating, on the organ or on the environment of the organ whose imaging is to be effected, three reference points chosen so as all to be visible on the views obtained by the various imagings, and in carrying out a calculation of correlation of the views obtained by the various imagings in order to bring them into a single referential system, taking into account the three reference points.
This method advantageously consists in carrying out, during the correlation operation, a smoothing of the points which is associated with the apparent densities of each view, omitting from the latter any zone in which the density of the points is below a predetermined value.
In accordance with one aspect of this invention, this method consists in using a support for each reference point, consisting of a surface, if appropriate delimited by a contrast frame, making it possible to site the distance of the point relative to the camera by a statistical estimation of the value of this distance on a number of points which is higher, the greater the surface, then in determining the center of the reference point by a progressive skeletonization operation.
Advantageously, and in order to avoid the disadvantages due to the precise determination of a point on a glancing plane, each surface associated with a reference
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Ueda, Ken, "Three-Dimensional Analysis for Prediction and Assessment of Mandibular Movement in Orthognathic Surgery in the Ramus", J. max-fac., Surg., 11, (1983), pp. 216-226.
Blouin Jean-Louis
Dechellete Gilles
Duret Francois
Cohen Lee S.
Dubno Herbert
Gilbert Samuel
Sopha Bioconcept S.A.
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