Magnetic determination of position and orientation
First Claim
Patent Images
1. Apparatus for determining position of an object comprising:
- (a) magnet means for generating a plurality of different magnetic fields in a sensing volume, each said field having at least one component having a magnitude which is quasilinear with respect to distance in a reference direction within said sensing volume, said magnitude being non-zero in at least some locations within said sensing volume;
(b) control means for actuating said magnet means to generate said fields in a predetermined sequence;
(c) a sensor connected to the object and movable within said sensing volume, and adapted to detect magnetic field components in at least two different local directions relative to the sensor and provide separate data representing each said component; and
(d) calculation means for determining the position of said sensor from said data representing said magnetic field components detected during generation of said fields.
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Abstract
A magnetic position and orientation determining system uses magnetic fields, desirably including uniform fields from Helmholtz coils positioned on opposite sides of a sensing volume and gradient fields generated by the same coils. By monitoring field components detected at the probes during application of these fields, the position and orientation of the probe in the field can be deduced. A representation of the probe can be superposed on a separately acquired image of the subject to show the position and orientation of the probe with respect to the subject.
1203 Citations
45 Claims
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1. Apparatus for determining position of an object comprising:
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(a) magnet means for generating a plurality of different magnetic fields in a sensing volume, each said field having at least one component having a magnitude which is quasilinear with respect to distance in a reference direction within said sensing volume, said magnitude being non-zero in at least some locations within said sensing volume; (b) control means for actuating said magnet means to generate said fields in a predetermined sequence; (c) a sensor connected to the object and movable within said sensing volume, and adapted to detect magnetic field components in at least two different local directions relative to the sensor and provide separate data representing each said component; and (d) calculation means for determining the position of said sensor from said data representing said magnetic field components detected during generation of said fields. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. Apparatus for determining orientation and position comprising:
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(a) a magnet structure including at least two pairs of Helmholtz coils, the coils of each said pair being substantially coaxial with one another and defining a pair axis, and being disposed on opposite sides of a sensing volume, the axes of said pairs being substantially orthogonal to one another; (b) control means for selectively actuating each said pair of Helmholtz coils in a homogeneous field state with codirectional current flow in both coils of the pair to thereby generate a magnetic field directed parallel to the pair axis of substantially uniform strength within said sensing volume, said control means also being operative to actuate each said pair of Helmholtz coils in a gradient field state with counterdirectional current flow in the coils of the pair to thereby generate a magnetic field having a component directed parallel to the axis of the pair, such component having a substantially linear gradient of magnitude in said sensing volume, said control means being operative to actuate said magnet structure so that only one pair of coils is actuated to only one state at any time; (c) a probe movable within said sensing volume, said probe having mounted thereon sensor means for measuring magnetic field components in at least two different local directions relative to the probe and providing separate data representing each said component, whereby said sensor means will measure homogeneous-field components in said local directions while coil pairs are in said homogeneous field states and said sensor means will measure gradient-field components in said local directions while said coil pairs are in said gradient-field states; and (d) calculation means for determining the orientation of said probe relative to said pair axes from said data representing homogeneous-field components and determining the position of said probe in said sensing volume from said data representing homogeneous-field components and said gradient-field components. - View Dependent Claims (15, 16, 17, 18)
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19. A method of determining the position of an object within a sensing volume comprising the steps of:
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(a) generating a plurality of different magnetic fields in said sensing volume in a predetermined sequence, each field having at least one component having a magnitude which is quasilinear with respect to distance in a reference direction within the sensing volume; (b) during generation of said fields measuring magnetic-field components in at least two different local directions relative to a sensor connected to the object to thereby provide separate data representing each of said magnetic field components; and (c) determining the position of said sensor within said sensing volume from said data representing said measured field components. - View Dependent Claims (20, 21)
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22. A method of displaying the location of a probe in a living subject comprising the steps of:
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(a) providing at least one fiducial marker in fixed position relative to the subject; (b) acquiring an image of the subject including a depiction of said at least one fiducial marker; (c) determining the locations of said at least one fiducial marker and of said probe in a common frame of reference by measuring magnetic fields transmitted to or from said probe and said fiducial marker, whereby a position of said probe relative to said at least one fiducial marker is known; and (d) superposing a representation of said probe on said image of said subject at a position relative to said depiction of said at least one fiducial marker corresponding to the position of said probe relative to said at least one fiducial marker in said common frame of reference. - View Dependent Claims (23, 24)
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25. A method of depicting a body part comprising the steps of:
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(a) providing a sensor in fixed position relative to the body part and determining an orientation of said sensor in a fixed frame of reference; (b) acquiring an image of the body part in a starting orientation; (c) monitoring the orientation of said sensor in said frame of reference by measuring individual components of magnetic fields transmitted to or from said sensor, to thereby determine a moved orientation of said body part after movement of the body part from said starting orientation; (d) transforming said image of said body part in said starting orientation into an image of said body part in said moved orientation and (e) displaying the transformed image. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32)
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33. Endoscopic apparatus comprising:
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(a) means for generating magnetic fields in a field frame of reference so that at least one parameter of said field is quasilinear with respect to distance from point to point within said field frame of reference; (b) a probe adapted for disposition in the patient'"'"'s body; (c) a sensor mounted on said probe for monitoring magnetic field components in at least two different local directions relative to said sensor prevailing at said sensor while said probe is disposed in the patient'"'"'s body and sending one or more sensor signals representing said components so that said one or more sensor signals including separate data representing each of said components; and (d) calculation means for determining the position of said probe in said frame of reference from said sensor signals while said probe is disposed in the patient'"'"'s body and providing probe position data representing the position of said probe in said field frame of reference based upon said sensor signals. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40)
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41. A method of operating a probe within a living patient comprising the steps of:
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(a) generating a magnetic field in a field frame of reference so that at least one parameter of said field is quasilinear with respect to distance from point to point within said frame of reference; (b) disposing a probe in the patient'"'"'s body so that said magnetic field impinges on said probe; (c) sensing individual components of the magnetic field prevailing at said probe in plurality of local directions relative to said probe while said probe is disposed in the patient'"'"'s body and sending one or more sensor signals incorporating separate data representing each said component of such magnetic field of said probe; (d) determining the position of said probe in said field frame of reference from said sensor signals while said probe is disposed in the patient'"'"'s body and providing probe position data representing the position of said probe in said field frame of reference.
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- 42. A method as claimed in claim 46 further comprising the steps of displaying an image of the patient'"'"'s body with a representation of said probe superposed thereon so that the representation of said probe is superposed at a location on said body image dependent upon said probe position data and observing said superposed representation to monitor the position of the probe within the patient'"'"'s body.
Specification