Surgery – Truss – Pad
Patent
1992-12-23
1995-06-06
Pfaffle, Krista M.
Surgery
Truss
Pad
25036304, 36441314, 36441319, 378901, 382128, A61B 500, G01T 100, G06K 920
Patent
active
054213304
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention concerns the examination of a body, by means of wave beams emerging therefrom. It applies more particularly, but not exclusively to tomography.
2. Related Art
The current embodiments in the field concern what may be termed "computed tomography" (see for example, the French Patent No. 74 14031 published under No. 2 227 582). The body to be examined is traversed by wave beams. Sensors in a specified position each receive a wave beam which emerges from the body with a specified direction. For each sensor, the sensed signals ("gross data") represent the accumulated effect of the body under radiation all along the trajectory of the wave beam in question.
In other words, each gross data signal represents the intensity of a wave beam of a given type which emerges from the body along an axis termed the "acquisition line". The axis in question may be designated by at least two parameters (such as a position parameter and an angular parameter). According to these axis parameters, the gross data define a "image of projections" of the radiation in a multidimensional space termed "space of projections". This is a dual space of real space (the physical observation space), because to each point of the space of projections, there corresponds a straight line and one only of real space.
Computed tomography is based on the following principle: if a sufficiently large set of gross data signals is available relating to acquisition lines passing through the body along different directions, then it must be possible to find the variation of absorption (or of emission) of the wave beam at each point of the examined body.
The drawback of computed tomography is that it requires a considerable number of calculations. It is therefore difficult and expensive to reconstitute the real image of the body in real time.
SUMMARY OF THE INVENTION
An essential object of the present invention is, on the contrary, to provide means which facilitate the use of the sensed information in real time.
A second object of the invention is to allow this sensed information to be used at the level of the image of projections, that is to say, without having to convert them necessarily into "reconstructed data" in real space.
A third object of the invention is to provide results from a restricted set of gross data, while the technique of the prior art necessitates in principle a complete knowledge of these data.
A fourth object of the invention is to provide more accurate results than before concerning the internal or external surfaces of the examined body.
The invention also aims to make possible not only the processing of absolute measurements, but also that of "differential" measurements obtained at the level of the sensors.
The invention moreover aims to allow an apparatus acting on the body to be directly controlled, in particular in real time.
The invention moreover opens a way for the dynamic tracking of objects, here again because of its potential for operating in real time.
For this purpose, the invention offers, first of all, a device for assistance with an examination of a body.
This device will acquire an ordered set of gross data signals such as defined above.
According to the invention, the processing means include means for the differential analysis of gross data signals relative to their axis parameters, to determine therein critical points where a jump in intensity of the sensed signal manifests itself. In this way, each one of these points corresponds to an acquisition line tangential to an internal (or external) boundary of the examined body. The axis parameters of the critical points then represent, as a whole, the position of at least one portion of the boundaries of the body.
Other characteristics and advantages of the invention will emerge on examining the detailed description given below and the attached drawings wherein:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is the general layout diagram of a tomography apparatus;
FIG. 2 is the operating diagram of a unidimen
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Ayache Nicholas
Thirion Jean-Philippe
Inria Institut National de Recherche en Informatique et en Autom
Pfaffle Krista M.
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