Apparatus and method for generating a magnetic field
A system whereby a magnetic tip attached to a surgical tool is detected, displayed and influenced positionally so as to allow diagnostic and therapeutic procedures to be performed rapidly, accurately, simply, and intuitively is described. The tools that can be so equipped include catheters, guidewires, and secondary tools such as lasers and balloons, in addition biopsy needles, endoscopy probes, and similar devices. The magnetic tip allows the position and orientation of the tip to be determined without the use of x-rays by analyzing a magnetic field. The magnetic tip further allows the tool tip to be pulled, pushed, turned, and forcefully held in the desired position by applying an appropriate magnetic field external to the patient's body. A Virtual Tip serves as an operator control. Movement of the operator control produces corresponding movement of the magnetic tip inside the patient's body. Additionally, the control provides tactile feedback to the operator's hand in the appropriate axis or axes if the magnetic tip encounters an obstacle. The output of the control combined with the magnetic tip position and orientation feedback allows a servo system to control the external magnetic field by pulse width modulating the positioning electromagnet. Data concerning the dynamic position of a moving body part such as a beating heart offsets the servo systems response in such a way that the magnetic tip, and hence the secondary tool is caused to move in unison with the moving body part. The tip position and orientation information and the dynamic body part position information are also utilized to provide a display that allows three dimensional viewing of the magnetic tip position and orientation relative to the body part.
1 . An apparatus for generating a magnetic field, comprising;
a first cluster of first electromagnet poles provided to a mass of magnetic material;
a first plurality of electromagnet coils provided to said first electromagnet poles, said first plurality of electromagnet coils controllable on a substantially separate basis;
a second cluster of second electromagnet poles provided to said mass of magnetic material such that said second cluster of second electromagnet poles substantially opposes said first cluster of first electromagnet poles, said magnetic mass completing a magnetic circuit from said first cluster said second cluster; and
a second plurality of electromagnet coils provided to said second electromagnet poles, said second plurality of electromagnet coils controllable on a substantially separate basis such that an orientation of a magnetic field in a region between said first cluster and said second cluster is controllable in multiple dimensions.
2 . The apparatus of claim 1 , wherein said first cluster of first electromagnet poles comprises three electromagnet poles.
3 . The apparatus of claim 1 , wherein pole faces of said first electromagnet poles lie substantially on a sphere.
4 . The apparatus of claim 1 , wherein pole faces of said first electromagnet poles lie substantially on a sphere and where pole faces of said second electromagnet poles lie substantially on said sphere.
5 . The apparatus of claim 1 , further comprising a system controller to control electric currents in said first plurality of coils and said second plurality of coils to control said orientation of said magnetic field.
6 . The apparatus of claim 1 , further comprising:
a tool having a distal end responsive to said orientation of said magnetic field; and
one or more magnetic sensors to sense a magnetic field produced by said distal end.
7 . The apparatus of claim 6 , said distal end comprising one or more magnetic field sensors and one or more temperature sensors.
8 . The apparatus of claim 6 , further comprising a Virtual Tip control device to allow user control inputs.
9 . The apparatus of claim 6 , further comprising a Virtual Tip that provides tactile feedback to an operator.
10 . The apparatus of claim 9 , wherein said Virtual Tip provides tactile feedback to an operator according to a position error between an actual position of said distal end and a desired position of said distal end.
11 . The apparatus of claim 6 , further comprising a system controller to control electric currents in said first plurality of coils and said second plurality of coils to control said orientation of said magnetic field to apply magnetic force to said distal end.