Surgery – Instruments – Stereotaxic device
Reexamination Certificate
2000-05-03
2001-05-01
Philogene, Pedro (Department: 3732)
Surgery
Instruments
Stereotaxic device
Reexamination Certificate
active
06224613
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a device for referencing a system of coordinates for observing and locating a body in space, with respect to its position, shape, and/or alignment in the local field of gravity. Location and tracking of the body in space can be built into the device and may consist of at least two independent means for determining such, involving transmission or emission and, in a complementary way, detection or reception.
BACKGROUND OF THE INVENTION
In many instances, portable or mobile measuring devices or imaging devices are used whose position has to be changed, depending upon the measurement being taken. Some of these devices change their behavior depending upon their alignment to the field of gravitation of the earth, e.g., because of changes in the dimensions or shape of the materials used. This can result in incorrect measurements or erroneous images. An accurate measurement of the line of the field of gravity of the earth in relation to the alignment of the measuring device is necessary in order to correct or to compensate for these errors.
French Patent Application No. 2608271 to Thome discloses a device for determining the vector of the gravitational force. This well-known device contains a body made of lead on a thread that can move freely in the horizontal position and which is aligned in a field of gravity. Balls having pre-marked centers have been arranged along this thread in such a way that the alignment of the centers of the balls makes it possible to determine the vector of the gravitational force. However, this well-known device only makes it possible to determine a three-dimensional system of coordinates whose vertical axis is defined by the vector of the gravitational force.
U.S. Pat. No. 5,197,476 to Nowacki discloses a device for determining a stable three-dimensional system of coordinates. This well-known device includes a three-dimensional frame that is equipped with Infra Red LEDs (Light Emitting Diodes), two infrared cameras and a computer. The positions of the Infrared LEDs in space are detected by means of the infrared cameras and those positions are then stored in the computer. After the frame is removed, the device measures the position of an ultrasound probe that also is equipped with Infrared LEDs and that can be moved manually within the volume previously defined by the frame relative to the previously stored positions of the Infrared LEDs on the frame. Hence, this device is only able to determine a stable three-dimensional system of coordinates that has no relation at all to the vector of the gravitational force.
It is at this juncture that the present invention wishes to provide a remedy. The present invention addresses the problem of determining a vector aligned in a local field of gravity. This vector lies within a space, for example within the space of an operating room, that has objects that are aligned in space and in relation to a stable system of coordinates. By incorporating the device made in accordance with the present invention in a CAS System (Computer Assisted Surgery System) a system of reference coordinates for measuring objects in medical robotics or in computer assisted surgical navigation can be established with an axis that runs parallel to the gravitational force.
SUMMARY OF THE INVENTION
The present invention is directed to a device for referencing a system of coordinates (
1
) in space (
2
), using a body (
4
) suspended in space (
2
) and aligned in the local field of gravity (
3
), wherein the body (
4
) may comprise a first set of at least two means (
5
) that can be optically, acoustically, or electromagnetically active and that can be placed at a distance, A, from each other beforehand, and wherein the device can be incorporated in a Computer Assisted Surgery (CAS) System. This system comprises a second set of at least two additional means (
5
) that can be optically, acoustically, or electromagnetically effective and which may interact with the first set of means (
5
) and also a plotting unit (
16
) for determining the spatial coordinates of the body. Advantageously, the first set of means (
5
) can include transmitters that emit electromagnetic or acoustic waves, and the second set of means can include optical or acoustical sensors (
13
). In a preferred arrangement, the first set of means includes acoustical receivers, and the second set of means includes acoustical receivers.
The body (
4
) can be suspended (
6
) by a thread, a wire, or a chain. Alternatively, the body (
4
) can be suspended (
6
) by being mounted on gimbals (
15
) or by a ball-and-socket-joint. In a preferred embodiments, the body (
4
) can be suspended (
6
) in space by being embedded in an elastomer, especially in silicon rubber, more especially in foamed silicon rubber.
The alignment of the body (
4
) in the field of gravity (
3
) may be damped, especially in one or more of the following ways: by a water bath (
7
) that surrounds the body (
4
); by springs; electromagnetically; by means of friction; and/or by air or gas pressure shock absorbers.
In preferred embodiments, at least one set of means used may encompass one or more of the following: optical emitters, reflectors, or receivers; Light Emitting Diodes (LEDs); or Infrared LEDs. Preferably, when the first set of means used includes LEDs or Infrared LEDs, the second set of means used may include optical emitters, reflectors, or receivers.
Preferably, the second set of means may include one or more of at least two cameras, at least two optical sensors, or at least two acoustic sensors. When the cameras are not stabilized, their position can be determined by analyzing a stable control point field. When the cameras are stabilized, the position of the space coordinates can be determined videographically. Alternately, the stabilized cameras may be digital.
When the second set of means are cameras, the first set of means can include at least one transmitter of electromagnetic waves, such that the position of the space coordinates may be determined by the combination of equipment. When the second set of means are acoustical sensors, the first set of means can include sound wave emitters or reflectors, such that the position of the space coordinates may be determined by the combination of equipment. Optionally, in this case, the position of the space coordinates may be determined through analysis of interference effects. When the second set of means includes optical sensors, the first set of means can include light wave emitters or reflectors, such that the position of the space coordinates may be determined by the combination of equipment. Optionally, in this case, the position of the space coordinates may be determined through analysis of interference effects.
In another preferred embodiment, the first set of means may comprise at least one coil used to set up a magnetic field. Preferably, the second set of means can further comprise at least two coils or at least two echo sensors to detect the magnetic field. Optionally, in such cases, the position of the space coordinates may be determined through analysis of either the magnetic induction or the echo effect.
Additionally, the first set of means used may include acoustical transmitters or reflectors, preferably at least two, and the second set of means may include microphones. Optionally, in this case, the position of the space coordinates may be determined through analysis of interference effects.
REFERENCES:
patent: 5197476 (1993-03-01), Nowacki et al.
patent: 5617857 (1997-04-01), Chader et al.
patent: 5792147 (1998-08-01), Evans et al.
patent: 5907395 (1999-05-01), Schulz et al.
patent: 2608271 (1988-06-01), None
patent: WO 86/06948 (1986-12-01), None
English translation of French Patent FR 2608271 A, previously disclosed with English abstract on May 3, 2000.
Pennie & Edmonds LLP
Philogene Pedro
Synthes (U.S.A.)
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