EP1372479A1 - Determining the position of a surgical probe - Google Patents

Determining the position of a surgical probe

Info

Publication number
EP1372479A1
EP1372479A1 EP02704971A EP02704971A EP1372479A1 EP 1372479 A1 EP1372479 A1 EP 1372479A1 EP 02704971 A EP02704971 A EP 02704971A EP 02704971 A EP02704971 A EP 02704971A EP 1372479 A1 EP1372479 A1 EP 1372479A1
Authority
EP
European Patent Office
Prior art keywords
magnetic field
detecting
coil
emitting
operative
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP02704971A
Other languages
German (de)
French (fr)
Inventor
Emanuel Ozair Lee 1 Ladythorn Crescent COHEN
John Fuller
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hall Effect Technologies Ltd
Original Assignee
Hall Effect Technologies Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hall Effect Technologies Ltd filed Critical Hall Effect Technologies Ltd
Publication of EP1372479A1 publication Critical patent/EP1372479A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/06—Devices, other than using radiation, for detecting or locating foreign bodies ; determining position of probes within or on the body of the patient
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/06—Devices, other than using radiation, for detecting or locating foreign bodies ; determining position of probes within or on the body of the patient
    • A61B5/061—Determining position of a probe within the body employing means separate from the probe, e.g. sensing internal probe position employing impedance electrodes on the surface of the body
    • A61B5/062—Determining position of a probe within the body employing means separate from the probe, e.g. sensing internal probe position employing impedance electrodes on the surface of the body using magnetic field

Definitions

  • the present invention relates to an apparatus and method for determining the
  • the present invention seeks to address these problems.
  • processing means operative to calculate the relative position of the means for emitting and means for detecting the magnetic field thereby to determine the position of the body.
  • the method and apparatus enable the position of a body to be determined.
  • associating apparatus for introduction into a human or animal body with either a means for
  • the body may comprise a surgical instrument, needle, catheter, prosthesis or the
  • the method and apparatus are for determining the position of the body in three dimensional space.
  • the means for emitting a magnetic field is adapted to be associated with the body and may comprise a permanent magnet, or some material that
  • the means for emitting a magnetic field is preferably incorporated in the body.
  • the means for detecting the magnetic field preferably comprises one or more galvomagnetic devices, for example Hall Effect devices.
  • galvomagnetic devices for example Hall Effect devices.
  • magnetic field is preferably operative to detect magnetic field in a number of different directions, preferably at least two and more preferably three mutually substantially orthogonal directions.
  • the means for detecting the magnetic field is preferably operative to detect magnetic field in a number of different directions, preferably at least two and more preferably three mutually substantially orthogonal directions.
  • each detector for example galvomagnetic devices, each mounted for rotation about an axis, and a drive means is preferably provided for each detector,
  • the axes of all the detectors may be substantially parallel, and may be substantially evenly spaced around the circumference of a circle.
  • the axes of the detectors may not be parallel.
  • the detectors may be movable along their respective axes.
  • Means are preferably provided for determining the direction of
  • each detector this may be achieved by employing drive means operative to orient the
  • the processing means are configured to control the processing means.
  • the processing means is preferably operative to monitor the strength of magnetic field detected by each detector in conjunction with its direction, as it rotates about its axis, thereby to determine the direction of magnetic field detected by the detector.
  • the processing means is preferably
  • location of a magnetic field emitting body can be determined by triangulation.
  • the means for detecting the magnetic field is adapted to be associated with the body and may comprise one or more galvomagnetic devices,
  • the means for detecting the magnetic field is preferably incorporated in the body.
  • the means for emitting a magnetic field is preferably operative to emit a magnetic field in a number of different directions, preferably at least two and more preferably three mutually substantially orthogonal directions.
  • the means for emitting a magnetic field preferably comprises one or more electromagnets. The or each
  • electromagnet preferably comprises a coil having a coil axis, each coil preferably comprises a length of material of high magnetic permeability to concentrate the magnetic
  • the or each coil is preferably mounted for rotation about an axis substantially perpendicular to the coil axis, more preferably about two substantially perpendicular axes each of which is substantially perpendicular to the axis of the coil.
  • a drive means is
  • each coil preferably provided for the or each coil, operative to oscillate it about the axis or axes
  • Means are preferably provided for energising the or each coil and where there is
  • each coil to energise each coil sequentially.
  • Means are preferably provided for determining the direction of each coil, this may be achieved by employing drive means
  • the processing means is preferably operative to monitor the strength of the magnetic field
  • the apparatus preferably includes a display operative
  • the display may comprise a computer monitor.
  • the display is preferably operative to show a two or three dimensional
  • a user can thus easily visualise the location of the body relative to the object, which, as the case may be, may be inside the object.
  • the processing means may comprise a computer.
  • a living body comprising a magnet and/or magnetisable material.
  • the apparatus may comprise a medical or surgical instrument, needle, catheter, prosthesis, or the like.
  • the magnet or magnetisable material may comprise a powdered material, for example a rare earth material.
  • the magnet or magnetisable material may be located at a part of the apparatus the position of which needs to be known, for example
  • apparatus for use in a living body comprising a means for detecting a magnetic field.
  • the apparatus may comprise a surgical instrument, needle, catheter, prosthesis or the like.
  • the means for detecting may comprise one or more galvomagnetic devices, for
  • the means for detecting is preferably located at a part of the apparatus the position of which needs to be known, for example the tip of a catheter.
  • Figure 1 shows a schematic view of an embodiment of apparatus according to the invention
  • Figure 2 shows the arrangement of the Hall devices of the apparatus of Figure 1 during use
  • Figures 3 a each show a cross-section through a catheter according to the
  • Figure 4 shows a schematic view of another embodiment of apparatus according to the invention.
  • FIG. 5 shows a schematic view of another embodiment of apparatus according to the invention.
  • Figure 6 shows another catheter according to the invention.
  • FIG. 7 shows another catheter according to the invention
  • substantially planar Hall effect devices 1 are each mounted for rotation about respective
  • Each Hall effect device 1 is mounted on a drive motor 2 operative to cause it to oscillate about its respective vertical axis. All three Hall effect devices 1 and associated
  • drive motors 2 are mounted on a vertical drive motor 3 operative to move the Hall effect devices in a direction parallel to the three vertical axes.
  • the term vertical is only being
  • Each Hall effect device 1 has an associated current source 4 and a differential amplifier 5 operative to amplify any Hall voltage generated by the Hall Effect device 1 -
  • amplifier 5 is fed via a single multiplexer 6 to an analogue to digital converter 7, the digital output of which is fed via a microcontroller 8 for signal processing and then to a personal computer 9 comprising a display 10.
  • the three Hall effect devices 1 are caused to rotate (which term includes oscillate), about their respective axes by means of the drive motors 2 At the same time the
  • Hall voltage generated across each Hall effect device 1 is monitored When the Hall devices 1 are exposed to a stationary magnetic field their Hall voltages will vary between a
  • microcontroller 8 and personal computer 9 determines the direction of field detected by
  • each Hall effect device 1 and then, knowing the relative positions of the three Hall effect devices 1 , calculates the position of the source of the magnetic field, and thus an object emitting the field, by triangulation.
  • each Hall effect device 1 is under the control of the microcontroller 8 and personal computer 9 and thus known at any given time
  • the source of the magnetic field is not substantially in the plane of the circle around which the Hall effect devices 1 are arranged it is preferable to move the Hall effect devices 1 along their rotational axes so that the source of the magnetic field is so
  • the personal computer 9 is also operative to produce an image on the display 10 indicating the position of a detected object, against a suitable background.
  • a particular use of the apparatus is the determination of the position of medical apparatus used in brain surgery relative to a patient's brain 1 1.
  • the apparatus would need to include means for emitting a magnetic field, such as a permanent magnet.
  • personal computer 8 is caused to display a representation of a person's head and brain
  • the apparatus could equally be used for other applications, including non-medical
  • the brain 1 1 shown in Figure 2 is for illustrative purposes only
  • the end of the catheter 12 is then inserted into an electrical coil 14 through which a direct electrical current is passed to magnetise the powder 13.
  • magnetised powder 13 to be introduced into the material forming the catheter 12 during
  • Figure 3c shows an alternative embodiment of a catheter including an annular magnetisable magnet 15.
  • the apparatus comprises three planar coils 16. Each coil has an axis 17 and a ferrite rod 18 extends through each coil substantially parallel to the axis 17.
  • the three coils 16 are disposed evenly around the circumference of a circle with their axes 17 pointing generally towards the centre of the circle.
  • Each coil 16 is mounted on a drive means (not shown) operative to oscillate the coil 16 by about 60° about each of two substantially perpendicular axis, each axis being substantially perpendicular to the coil axis 17 when in the illustrated
  • Each coil 16 is supplied, in turn, with a direct or pulsed electrical current causing
  • the coil 16 to produce a magnetic field extending generally along the coil axis 17.
  • the apparatus is able to determine the position of a means for detecting a magnetic field disposed in the region surrounded by the coils 16
  • microprocessor preferably a personal computer.
  • the apparatus includes a means for detecting a magnetic field connected to a processor to which the drive means of
  • the coils 16 are also connected.
  • the relative position of the means for detecting magnetic field and the coils can then be determined.
  • the position of the coils 16 is known the position of the means for detecting magnetic field and hence of the medical apparatus can
  • This is conveniently displayed by a computer monitor caused to display a representation of the patient's heart along with a suitable symbol to indicate the position of the medical apparatus in the heart.
  • Figure 5 shows an arrangement similar to that of Figure 4, but with only a single
  • a single coil 16 is sufficient to determine the position of a means for detecting
  • Figures 6 and 7 show catheters 19 comprising a plastics tube having a Hall Effect device or devices 20 incorporated therein.
  • Leads 21 for supplying a drive current and enabling the Hall voltage to be measured extend from the Hall Effect device(s) embedded in the wall of the catheter and out through the outside of the wall of the catheter at a point

Landscapes

  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Molecular Biology (AREA)
  • Biophysics (AREA)
  • Pathology (AREA)
  • Biomedical Technology (AREA)
  • Human Computer Interaction (AREA)
  • Medical Informatics (AREA)
  • Physics & Mathematics (AREA)
  • Surgery (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
  • Media Introduction/Drainage Providing Device (AREA)
  • Measurement And Recording Of Electrical Phenomena And Electrical Characteristics Of The Living Body (AREA)

Abstract

Apparatus for determining the position of a body in space including a means for emitting a magnetic field (13, 15, 16) and a means for detecting (1, 20) the emitted magnetic field. One of either the means for emitting or detecting is associated with the body, and a processing means 9 is provided operative to calculate the relative position of the means for emitting and the means for detecting thereby to determine the position of the body. The apparatus is particularly intended for medical applications and may be used for detecting the position of medical apparatus inside a living body.

Description

DETERMINING THE POSITION OF ASURGICAL PROBE
The present invention relates to an apparatus and method for determining the
position of a body particularly, although not exclusively, for determining the position of a body within a human or animal body, and to a body.
In branches of medicine, particularly keyhole surgery, apparatus is introduced into a living body and it is desirable to know the position of that apparatus in the body. It is known to locate such apparatus using x-rays. There are, however, two drawbacks with
this approach. Materials from which some apparatus for introduction into the human body
is made, for example plastics materials, exhibit very low absorption of x-rays making their
position difficult to determine using x-rays; and prolonged exposure of a living body to x-rays is undesirable.
The present invention seeks to address these problems.
According to a first aspect of the present invention there is provided apparatus for
determining the position of a body in a space comprising a means for emitting a magnetic
field and a means for detecting the emitted magnetic field, one of which means may be associated with the body, and processing means operative to calculate the relative position of the means for emitting and means for detecting the magnetic field thereby to determine the position of the body.
According to a second aspect of the present invention there is provided a method
of determining the position of a body in a space comprising the steps of: providing means
for emitting a magnetic field and means for detecting the emitted magnetic field;
associating either the means for emitting or means for detecting the magnetic field with the body and locating the other means at a position spaced apart from the body; causing the means for emitting a magnetic field to emit a magnetic field and
detecting the magnetic field with the means or detecting the magnetic field thereby to determine the position of the body.
The method and apparatus enable the position of a body to be determined. By associating apparatus for introduction into a human or animal body with either a means for
emitting or a means for detecting a magnetic field it is possible to determine the position
of the apparatus when introduced into the body.
The body may comprise a surgical instrument, needle, catheter, prosthesis or the
like.
Preferably the method and apparatus are for determining the position of the body in three dimensional space.
In one embodiment the means for emitting a magnetic field is adapted to be associated with the body and may comprise a permanent magnet, or some material that
can be induced to emit a magnetic field by application of an external field. The means for emitting a magnetic field is preferably incorporated in the body.
The means for detecting the magnetic field preferably comprises one or more galvomagnetic devices, for example Hall Effect devices. In order to enable the position of the body to be determined in multi-dimensional space the means for detecting the
magnetic field is preferably operative to detect magnetic field in a number of different directions, preferably at least two and more preferably three mutually substantially orthogonal directions. In one arrangement the means for detecting the magnetic field
comprises three separate detectors, for example galvomagnetic devices, each mounted for rotation about an axis, and a drive means is preferably provided for each detector,
operative to oscillate it about its axis. The axes of all the detectors may be substantially parallel, and may be substantially evenly spaced around the circumference of a circle.
Alternatively, the axes of the detectors may not be parallel. The detectors may be movable along their respective axes. Means are preferably provided for determining the direction of
each detector, this may be achieved by employing drive means operative to orient the
detectors in predetermined directions, for example stepper motors. The processing means
is preferably operative to monitor the strength of magnetic field detected by each detector in conjunction with its direction, as it rotates about its axis, thereby to determine the direction of magnetic field detected by the detector. The processing means is preferably
further operative to determine the position of the source of a magnetic field detected by the detectors by comparing the direction of magnetic field detected by each detector.
Because the position of each detector is known the source of a detected field, and thus
location of a magnetic field emitting body, can be determined by triangulation.
In another embodiment the means for detecting the magnetic field is adapted to be associated with the body and may comprise one or more galvomagnetic devices,
preferably Hall Effect devices. The means for detecting the magnetic field is preferably incorporated in the body.
The means for emitting a magnetic field is preferably operative to emit a magnetic field in a number of different directions, preferably at least two and more preferably three mutually substantially orthogonal directions. In one arrangement the means for emitting a magnetic field preferably comprises one or more electromagnets. The or each
electromagnet preferably comprises a coil having a coil axis, each coil preferably comprises a length of material of high magnetic permeability to concentrate the magnetic
field produced along the coil axis.
The or each coil is preferably mounted for rotation about an axis substantially perpendicular to the coil axis, more preferably about two substantially perpendicular axes each of which is substantially perpendicular to the axis of the coil. A drive means is
preferably provided for the or each coil, operative to oscillate it about the axis or axes
about which it may rotate.
Means are preferably provided for energising the or each coil and where there is
more than one coil to energise each coil sequentially. Means are preferably provided for determining the direction of each coil, this may be achieved by employing drive means
operative to orient the detectors in predetermined directions, for example stepper motors. The processing means is preferably operative to monitor the strength of the magnetic field
detected as the or each coil is sequentially energised and rotated, thereby to determine the direction of the means for detecting the magnetic field relative to the means for emitting
the magnetic field.
By determining the direction of the means for detecting magnetic field relative to different coils and/or coils oriented in different directions it is possible to determine the location of the means for detecting the magnetic field relative to the means for emitting the
magnetic field.
Further, in both embodiments the apparatus preferably includes a display operative
to display the determined position of the body. The display may comprise a computer monitor. The display is preferably operative to show a two or three dimensional
representation of an object, such as a person's head, and the position of a body in relation to that object, such as the tip of a surgical instrument, along with the representation of the
object. A user can thus easily visualise the location of the body relative to the object, which, as the case may be, may be inside the object.
The processing means may comprise a computer.
According to a third aspect of the present invention there is provided a method of causing apparatus for use in a living body to emit a magnetic field comprising the steps of
incorporating a magnetisable material into the apparatus and then exposing the apparatus
to a magnetic field thereby to magnetise the magnetisable material in the apparatus.
According to a fourth aspect of the present invention there is provided apparatus
for use in a living body comprising a magnet and/or magnetisable material.
The apparatus may comprise a medical or surgical instrument, needle, catheter, prosthesis, or the like. The magnet or magnetisable material may comprise a powdered material, for example a rare earth material. The magnet or magnetisable material may be located at a part of the apparatus the position of which needs to be known, for example
the tip of a catheter.
According to a fifth aspect of the present invention there is provided apparatus for use in a living body comprising a means for detecting a magnetic field.
The apparatus may comprise a surgical instrument, needle, catheter, prosthesis or the like. The means for detecting may comprise one or more galvomagnetic devices, for
example a Hall Effect device. The means for detecting is preferably located at a part of the apparatus the position of which needs to be known, for example the tip of a catheter.
In order that the invention may be more clearly understood, embodiments thereof will now be described by way of example with reference to the accompanying drawings of which:
Figure 1 shows a schematic view of an embodiment of apparatus according to the invention;
Figure 2 shows the arrangement of the Hall devices of the apparatus of Figure 1 during use;
Figures 3 a each show a cross-section through a catheter according to the
to c invention;
Figure 4 shows a schematic view of another embodiment of apparatus according to the invention;
Figure 5 shows a schematic view of another embodiment of apparatus according to the invention; Figure 6 shows another catheter according to the invention; and
Figure 7 shows another catheter according to the invention
Referring to Figures I and 2 there is shown apparatus for detecting the position of
a magnetic field emitting body in three dimensional space. Three substantially flat,
substantially planar Hall effect devices 1 are each mounted for rotation about respective
vertical axes, the three axes being substantially evenly spaced around the circumference of a circle. Each Hall effect device 1 is mounted on a drive motor 2 operative to cause it to oscillate about its respective vertical axis. All three Hall effect devices 1 and associated
drive motors 2 are mounted on a vertical drive motor 3 operative to move the Hall effect devices in a direction parallel to the three vertical axes. The term vertical is only being
used for illustrative purposes, the three axis of rotation of the Hall effect devices could
extend in any direction as appropriate. Each Hall effect device 1 has an associated current source 4 and a differential amplifier 5 operative to amplify any Hall voltage generated by the Hall Effect device 1 -
this being indicative of the detection of a magnetic field The output from each differential
amplifier 5 is fed via a single multiplexer 6 to an analogue to digital converter 7, the digital output of which is fed via a microcontroller 8 for signal processing and then to a personal computer 9 comprising a display 10.
In use the three Hall effect devices 1 are caused to rotate (which term includes oscillate), about their respective axes by means of the drive motors 2 At the same time the
Hall voltage generated across each Hall effect device 1 is monitored When the Hall devices 1 are exposed to a stationary magnetic field their Hall voltages will vary between a
maximum when the field is perpendicular to the plane of the devices 1 and a minimum when the field is parallel to the plane of the devices 1 By monitoring the varying Hall voltage produced by each Hall device 1 in conjunction with its rotational direction the
microcontroller 8 and personal computer 9 determines the direction of field detected by
each Hall effect device 1 and then, knowing the relative positions of the three Hall effect devices 1 , calculates the position of the source of the magnetic field, and thus an object emitting the field, by triangulation.
The rotational direction of each Hall effect device 1 is under the control of the microcontroller 8 and personal computer 9 and thus known at any given time
Where the source of the magnetic field is not substantially in the plane of the circle around which the Hall effect devices 1 are arranged it is preferable to move the Hall effect devices 1 along their rotational axes so that the source of the magnetic field is so
positioned, to increase the strength of the field being measured. The personal computer 9 is also operative to produce an image on the display 10 indicating the position of a detected object, against a suitable background. For example, a particular use of the apparatus is the determination of the position of medical apparatus used in brain surgery relative to a patient's brain 1 1. The apparatus would need to include means for emitting a magnetic field, such as a permanent magnet. For this application the
personal computer 8 is caused to display a representation of a person's head and brain
along with a suitable symbol to indicate the position of apparatus being manipulated in the brain by a surgeon. This enables to surgeon to see a real time representation of the position of the apparatus relative to a patient's head during the surgery.
The apparatus could equally be used for other applications, including non-medical
applications. The brain 1 1 shown in Figure 2 is for illustrative purposes only
Referring to Figures 3 a and b, to enable the position of a plastics catheter 12 to be
determined by the apparatus shown in Figures 1 and 2 a quantity of magnetisable powder 13, such as a rare earth powder, is incorporated into the end of the catheter 12 during manufacture. The end of the catheter 12 is then inserted into an electrical coil 14 through which a direct electrical current is passed to magnetise the powder 13. Were ready
magnetised powder 13 to be introduced into the material forming the catheter 12 during
manufacture it would be difficult for it to be distributed evenly, due to its tendency to clump together.
Figure 3c shows an alternative embodiment of a catheter including an annular magnetisable magnet 15.
Referring to figure 4 there is shown a schematic view of the spatial arrangement of
another embodiment of apparatus for determining the position of a body. The apparatus comprises three planar coils 16. Each coil has an axis 17 and a ferrite rod 18 extends through each coil substantially parallel to the axis 17. The three coils 16 are disposed evenly around the circumference of a circle with their axes 17 pointing generally towards the centre of the circle. Each coil 16 is mounted on a drive means (not shown) operative to oscillate the coil 16 by about 60° about each of two substantially perpendicular axis, each axis being substantially perpendicular to the coil axis 17 when in the illustrated
position.
Each coil 16 is supplied, in turn, with a direct or pulsed electrical current causing
the coil 16 to produce a magnetic field extending generally along the coil axis 17.
The apparatus is able to determine the position of a means for detecting a magnetic field disposed in the region surrounded by the coils 16
By measuring the strength of detected magnetic field, with a knowledge of which coil 16 is energised and its direction at any given time and by sequentially energising the
coils it is possible to determine the position and orientation of the means for detecting a magnetic field relative to the coil since the size of the magnetic field detected will depend upon the relative distance and orientation of a means for detecting a magnetic field and an
energised coil.
Calculating the position and orientation of a means for detecting magnetic field
may be performed by a microprocessor, preferably a personal computer.
An example use of the apparatus is the determination of the position of medical apparatus used in heart surgery relative to a patient's heart. The apparatus includes a means for detecting a magnetic field connected to a processor to which the drive means of
the coils 16 are also connected. The relative position of the means for detecting magnetic field and the coils can then be determined. As the position of the coils 16 is known the position of the means for detecting magnetic field and hence of the medical apparatus can
be determined.
This is conveniently displayed by a computer monitor caused to display a representation of the patient's heart along with a suitable symbol to indicate the position of the medical apparatus in the heart.
Figure 5 shows an arrangement similar to that of Figure 4, but with only a single
coil 16. A single coil 16 is sufficient to determine the position of a means for detecting
magnetic field.
Figures 6 and 7 show catheters 19 comprising a plastics tube having a Hall Effect device or devices 20 incorporated therein. Leads 21 for supplying a drive current and enabling the Hall voltage to be measured extend from the Hall Effect device(s) embedded in the wall of the catheter and out through the outside of the wall of the catheter at a point
away from the Hall Effect device(s). These catheters are intended for use with the
apparatus of either Figure 4 or 5, to enable the position of the tip of the catheter to be determined relative to the coil(s).
The above embodiments are described by way of example only. Many variations are possible without departing from the invention.

Claims

1. Apparatus for determining the position of a body in a space comprising a means for emitting a magnetic field and a means for detecting the emitted magnetic field, one of which means may be associated with the body, and processing means operative to calculate the relative position of the means for emitting and means for
detecting the magnetic field thereby to determine the position of the body.
2. Apparatus as claimed in claim 1 , wherein the means for detecting the magnetic
field comprises one or more galvomagnetic devices.
3. Apparatus as claimed in either claim 1 or claim 2, wherein the means for detecting the magnetic field is operative to detect magnetic field in a number of different directions.
4. Apparatus as claimed in any preceding claim, wherein the means for detecting magnetic field comprises three separate detectors each mounted for rotation about
a respective axis.
5. Apparatus as claimed in claim 4, wherein a drive means is associated with each detector operative to oscillate the detector about its respective axis.
6. Apparatus as claimed in either claim 4 or 5, wherein means are provided for determining the direction of each detector.
7. Apparatus as claimed in claim 6, wherein the processing means is operative to monitor the strength of magnetic field detected by each detector in conjunction
with its direction, as it rotates about its axis, thereby to determine the direction of
magnetic field detected by the detector.
8. Apparatus as claimed in any preceding claim, wherein the means for emitting a magnetic field is incorporated in the body the position of which is to be
determined.
9. Apparatus as claimed in either claim 1 or 2, wherein the means for emitting a
magnetic field is operative to emit a magnetic field in a number of different directions.
10. Apparatus as claimed in clam 9, wherein the means for emitting a magnetic field comprises one or more coils each having an coil axis.
1 1. Apparatus as claimed in claim 10, wherein the or each coil is mounted for rotation
about an axis substantially perpendicular to its coil axis.
12. Apparatus as claimed in claim 1 1 , wherein the or each coil is mounted for rotation
about two substantially perpendicular axes, each of which is substantially perpendicular to the coil axis.
13. Apparatus as claimed in either claim 1 1 or 12, wherein a drive means is provided for the or each coil, operative to oscillate it about the axis or axes about which it
may rotate.
14. Apparatus as claimed in any of claims 10 to 13 comprising means for energising
the or each coil, said means being operative where there is more than one coil to energise the coils sequentially.
15. Apparatus as claimed in any of claims 10 to 14 comprising means for determining the direction of the or each coil
16. Apparatus as claimed in any of claims 10 to 15, wherein the processing means is
operative to monitor the strength of the magnetic field detected as the or each coil is energised and rotated, thereby to determine the direction of the means for detecting the magnetic field relative to the means for emitting the magnetic field.
17. Apparatus as claimed in any preceding claim comprising a display operative to display the determined position of the body.
18. A method of determining the position of a body in a space comprising the steps of:
providing means for emitting a magnetic field and means for detecting the emitted
magnetic field; associating either the means for emitting or means for detecting the magnetic field with the body and locating the other means at a position spaced
apart from the body; causing the means for emitting a magnetic field to emit a magnetic field and detecting the magnetic field with the means or detecting the
magnetic field thereby to determine the position of the body.
19. A method as claimed in claim 18 performed using the apparatus of any of claims 1 to 17.
20. A method as claimed in either claim 18 or 19, wherein the body is disposed in a human or animal body.
21. A method of causing apparatus for use in a living body to emit a magnetic field comprising the steps of incorporating a magnetisable material into the apparatus
and then exposing the apparatus to a magnetic field thereby to magnetise the
magnetisable material in the apparatus.
22. Apparatus for use in a living body comprising a magnet and/or magnetisable material.
23. Apparatus for use in a living body comprising a means for detecting a magnetic
field.
24. Apparatus as claimed in either claim 22 or 23, wherein the apparatus is a medical or surgical instrument, needle, catheter or prosthesis.
25. Apparatus as claimed in either claim 22 or 24 when dependent on claim 22, wherein the magnet or magnetisable material comprises a powdered material.
26. Apparatus as claimed in either claim 23 or 24, when dependent on claim 23,
wherein the means for detecting comprises one or more galvomagnetic devices.
EP02704971A 2001-03-14 2002-03-13 Determining the position of a surgical probe Withdrawn EP1372479A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GB0106354 2001-03-14
GBGB0106354.4A GB0106354D0 (en) 2001-03-14 2001-03-14 Method and apparatus for determining the position of a magnetic field emitting body and magnetic field emitting body
PCT/GB2002/001150 WO2002071943A1 (en) 2001-03-14 2002-03-13 Determining the position of asurgical probe

Publications (1)

Publication Number Publication Date
EP1372479A1 true EP1372479A1 (en) 2004-01-02

Family

ID=9910708

Family Applications (1)

Application Number Title Priority Date Filing Date
EP02704971A Withdrawn EP1372479A1 (en) 2001-03-14 2002-03-13 Determining the position of a surgical probe

Country Status (4)

Country Link
EP (1) EP1372479A1 (en)
CN (1) CN1525833A (en)
GB (1) GB0106354D0 (en)
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