Surgery – Instruments – Stereotaxic device
Patent
1995-02-10
1997-01-07
Hafer, Robert A.
Surgery
Instruments
Stereotaxic device
128774, 128845, A61B 1900, A61B 5103
Patent
active
055911757
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a device for fixing a person's head in a coordinate system.
Rhinostereometry is an optical method used for measuring the congestion of the nasal mucosa. The head of the person to be subjected to such measuring is fixed in a coordinate system. The positions in the coordinate system of a number of points on the nasal mucosa are determined by means of a surgical microscope which is placed on a micrometer table and is movable in all three dimensions.
In order for rhinostereometry to repeatedly yield comparable results, the head of the person subjected to such measuring has to be fixed in the same position on different occasions. Accurate fixation is of the utmost importance, since a point on the nasal mucosa moves about 4 mm at the most when the mucosa changes from a state of minimum congestion to one of maximum congestion.
The object of the invention is to provide a device enabling repeated and highly accurate fixation of a person's head in a coordinate system.
This object is achieved by a device having the distinctive features recited in appended claim 1. With the inventive device, a person's head can be fixed time after time in the same position in the coordinate system by setting the pressure transducers in previously recorded positions in the coordinate system and ensuring that each transducer is acted on by a predetermined pressure from the person's head.
Fixation is facilitated and can be done more quickly if the pressure transducers are disposed on a common support means which is movably arranged on a frame and thus can be used for roughly positioning the pressure transducers.
Preferably, the support means has the shape of a spectacle frame, two pressure transducers being arranged as pad bridges. In fixation, the pad bridges of the support means are moved downwards over the nasal bone as when glasses are put on.
Preferably, the remaining pressure transducers on the support means are so arranged as to be contacted with the forehead as well as the head close to the eyes during fixation. This arrangement of the pressure transducers is advantageous, in that the skull is here close beneath the skin, enabling more accurate fixation.
An embodiment of the invention will now be described in detail with reference to the accompanying drawing, in which
FIG. 1 schematically illustrates an embodiment of a fixing device according to the invention; and
FIG. 2 is an example of a pressure transducer to be used in the inventive device.
Thus, FIG. 1 shows an inventive fixing device comprising a vertically adjustable table 1, on which are mounted a vertically adjustable chin rest 2 and a fixed frame 3. Two limbs 4, on which a spectacle frame 5 is movably mounted, are fixedly arranged on the frame 3. The spectacle frame 5 can be fixed in different positions on the limbs 4, and its position thereon can be recorded by means provided therefor (not shown). Five pressure transducers 6-10 are mounted on the spectacle frame, but are merely schematically illustrated in the drawing in the form of "buttons". Two pressure transducers 6, 7 form pad bridges for the spectacle frame and are adapted to be contacted with the test subject's face at the nasal bone in the same manner as the pad bridges of ordinary glasses. A pressure transducer 8 is provided at the upper edge of the spectacle frame 5 so as to come into contact with the test subject's forehead when the pressure transducers 6, 7 in the form of pad bridges contact the nasal bone. The other two pressure transducers 9, 10 are provided at the side edges of the spectacle frame 5 and are adapted to come into contact with the test subject's face close to the eyes where the skull is just beneath the skin. For instance, the pressure transducers may have a surface of engagement with the face of about 3 mm.sup.2. Naturally, the number of pressure transducers and their positions may vary.
FIG. 2 shows by way of example the design of a pressure transducer that may be used in the device of FIG. 1. The pressure transducer has a fixed holder 20, and a pressure-sensing
REFERENCES:
patent: 3614950 (1971-10-01), Rabey
patent: 3658054 (1972-04-01), Iberall
patent: 4256112 (1981-03-01), Kopf et al.
patent: 4530367 (1985-07-01), Desjardinis et al.
patent: 5192254 (1993-03-01), Young
Hafer Robert A.
Koo Benjamin
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