Optics: measuring and testing – Angle measuring or angular axial alignment – With photodetection remote from measured angle
Patent
1994-04-26
1996-01-09
Hellner, Mark
Optics: measuring and testing
Angle measuring or angular axial alignment
With photodetection remote from measured angle
36441314, 36441315, 36441326, 378 15, 378 19, G01B 1126, G06F 1500
Patent
active
054833337
DESCRIPTION:
BRIEF SUMMARY
The present invention relates essentially to a method and an apparatus for determining the exact position of a target relative to a reference point of known coordinates with a receiving device comprising a linear active part formed from a variety of discrete radiation-sensitive elements.
The invention relates more particularly also to the use of the method and apparatus for determining the exact position of a target in an apparatus for the treatment of a target, preferably by pressure waves. According to a preferred embodiment, it is an apparatus for the treatment by pressure waves of a target selected from the group consisting of a lithiasis, for instance a renal or biliary lithiasis; of tissues, for instance benign or malignant tumors; bones, for instance a fracture or a bone zone to be treated, notably an osteoporosis zone.
Various methods and apparatuses are already known for determining the exact position of a target, comprising the use of a source of radiation emitting radiation capable of being received by a receiver device for this radiation, said source and said receiver device being disposed on opposite sides of said target (see EP-A-0,240,565 or EP-A-0,260,550).
Document Siemens DE-U-87/13,524=U.S. Pat. No. 4,914,588 describes an apparatus for forming an image by tomography requiring for constructing the image a rotating step around a rotation axis parallel to the patient's body to turn around it. The patient is usually displaced with a supporting table and this device requires a supplementary locating ultrasonic system.
Similarly, document EP-A-318,106 Philips=U.S. Pat. No. 4,967,735 describes an apparatus for the destruction of concretions comprising a fluoroscopic system combined with a system for detecting emitted photons, with the use of a diaphragm comprising a position of full opening and a position of reduced opening. The position, notably of the radiation source, appears to be fix, which generally implies an important irradiation of the patient.
It is further known, by document U.S. Pat. No. 4,764,944 (Finlayson) a method and a device for positioning a concretion located inside a patient's kidney using two convergent and penetrating radiation sources which intersect at focal point F2 consituting the external focus of an ellipsoid where are generated shock waves. Here, the initial position of the sources is not known but on the contrary must be very precise to intersect at the focal point. Besides, the technical solution proposed by Finlayson requires a calibrating step to determine the value of angle a between the coordinates in the observation plane and determine the angle between the observation plane and the horizontal. It is used in particular a rod terminated by a ball which is observed until the radiation observed by the fluoroscopes is centered on the intersecting point of each of the screens. This procedure is extremely complexe and requires, in all the cases of use, two sources and two receiver devices, in particular fluoroscopes whose initial position must be well determined for each one of them by the second focus, which requires that the sources be linked permanently to the treatment device, here an ellipsoid. Besides, a calibrating is necessary with the help of the device comprising a ball to bring the ball image at the center of the fluoroscope screens.
Furthermore, it is also described, in document WO-A-91/07913, a method and device for determining the position of a target using a mask-forming device combined with a film sensitive to X-rays. This solution, which is safe and reliable, requires nevertheless a minimum time for developping the film which is not always compatible with the industrial and medical requirements.
Thus, a main object of the present invention is to solve the new technical problem consisting in providing a solution enabling to determine the exact position of a target in a relatively short time while being of a great reliability and reproductibility.
A further main object of the present invention is to solve the new technical problem consisting in the
REFERENCES:
patent: 4041315 (1977-08-01), Hounsfield
patent: 4764944 (1988-08-01), Finlayson
patent: 4914588 (1990-04-01), Schittenhelm
Hellner Mark
Technomed Medical Systems
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