System and method for controlling movement of a surgical tool
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 . A method for controlling movement of a tool having a distal end to be inserted in a body, comprising;
applying a force to said distal end by generating an external magnetic field;
regulating said force to move said distal end in a desired direction; and
locating said distal end by measuring a magnetic field of said distal end.
2 . The method of claim 1 , further comprising changing a visual representation of said distal end in substantially real time as said distal end moves through the body.
3 . The method of claim 1 , further comprising controlling one or more electromagnets to produce said external magnetic field.
4 . The method of claim 1 , further comprising measuring a temperature of one or more magnetic field sensors that measure said magnetic field of said distal end.
5 . The method of claim 1 , further comprising determining a current position of said distal end in comparison to a desired location.
6 . The method of claim 5 , wherein determining said current position of said tool distal end comprises:
inhibiting modulator outputs of a system controller;
inputting a dynamic cardio position via a communication controller; and
calculating said current position as a function of said cardio position.
7 . The method of claim 1 , further comprising computing a position error of said distal end.
8 . The method of claim 7 , further comprising altering at least one of a duty cycle and a polarity of modulation inputs to at least one of said X-axis controller, said Y-axis controller, and said Z-axis controller when said position error is greater than a specified minimum value.
9 . The method of claim 7 , further comprising producing a tactile feedback if said position error exceeds a predetermined amount along at least one axis.
10 . The method of claim 1 , wherein said system controller causes said tool distal end to move so that its position corresponds to position data from a Virtual Tip.
11 . A method for controlling movement of a tool having a distal end to be inserted in a body, comprising;
calculating a desired direction of movement for said distal end;
computing a magnetic field needed to produce said movement;
controlling a plurality of electric currents to produce said magnetic field; and
locating said distal end by measuring a magnetic field of said distal end.
12 . The method of claim 1 , wherein said computing a magnetic field comprises:
determining a current position of said distal end with respect to one or more magnet poles; and
using a lookup table to find said magnetic field needed to produce said movement.
13 . The method of claim 11 , further comprising controlling one or more electromagnets to produce said external magnetic field.
14 . The method of claim 11 , further comprising measuring a temperature of one or more magnetic field sensors that measure said magnetic field of said distal end.