Modeling positions of implanted devices in a patient

Abstract

Technology is disclosed for modeling positions of implanted devices in a patient. In various embodiments, the technology can construct a forward model that predicts an electrical impedance between electrical contacts; detects an actual electrical impedance between electrical contacts; computes a fitness value based on a comparison between the detected electrical impedance and the predicted electrical impedance; varies at least one parameter of the forward model until the computed fitness value is a maximum fitness value; and displays at a display device a estimated position of the first lead and/or second leads.

1 - 18 . (canceled) 
     
     
         19 . A system for treating patients, comprising:
 a processor and memory;   a forward model component;   a fitness computer component; and   an impedance detector component.   
     
     
         20 . The system of  claim 19 , wherein the forward model component is configured to take as a parameter at least a z-coordinate of a second lead in comparison to a first lead. 
     
     
         21 . The system of  claim 20 , wherein the forward model component is configured to generate a predicted electrical impedance by predicting an electrical impedance at a contact wherein the electrical impedance is a measure of contact-tissue impedance. 
     
     
         22 . The system of  claim 21 , wherein the fitness computer component is configured to compute a fitness between the predicted electrical impedance and an actual electrical impedance at the contact measured by the impedance detector component. 
     
     
         23 . The system of  claim 22  further comprising a component configured to vary at least the z-coordinate through iterations until a best fit is achieved. 
     
     
         24 . (canceled) 
     
     
         25 . The system of  claim 19  wherein the forward model component is configured to identify a position of a second lead of a signal delivery system relative to a first lead of the signal delivery system. 
     
     
         26 . The system of  claim 25  wherein the forward model component utilizes a coordinate system to identify position of the second lead relative to the first lead, and wherein said forward model component takes as an input at least one or more of:
 a z-coordinate parameter of the second lead in comparison to the first lead; 
 an r parameter indicative of either a radial distance between a specified contact on each of the first lead and the second lead or a radial distance between an axis of the coordinate system and a corresponding contact of the second lead; 
 a θ parameter indicative of an inclination of the second lead measured from a zenith located on a z-axis; and 
 a φ parameter indicative of an azimuth of the second lead measured counter-clockwise from a plane formed the first lead and a contact of the second lead. 
 
     
     
         27 . The system of  claim 25  wherein the forward model component utilizes a coordinate system to identify position of the second lead relative to the first lead, and wherein said forward model component takes as inputs each of:
 a z-coordinate parameter of a second lead in comparison to a first lead; 
 an r parameter indicative of either a radial distance between a specified contact on each of the first lead and the second lead or a radial distance between an axis of the coordinate system and a corresponding contact of the second lead; 
 a θ parameter indicative of an inclination of the second lead measured from a zenith located on a z-axis; and 
 a φ parameter indicative of an azimuth of the second lead measured counter-clockwise from a plane formed the first lead and a contact of the second lead. 
 
     
     
         28 . The system of  claim 25  wherein said forward model component utilizes parameters from at least one of Cartesian coordinates, cylindrical coordinates and spherical coordinates to identify a position of a second lead of a signal delivery system relative to a first lead of the signal delivery system. 
     
     
         29 . The system of  claim 25  wherein said forward model component utilizes parameters from Cartesian coordinates, cylindrical coordinates and spherical coordinates to identify a position of a second lead of a signal delivery system relative to a first lead of the signal delivery system. 
     
     
         30 . The system of  claim 19  wherein said forward model component comprises a forward model of expected impedance measured between contacts of leads of a signal delivery system. 
     
     
         31 . The system of  claim 30  wherein said forward model takes as input various parameters, including at least one or more of geometric parameters, rotational parameters and physical parameters associated with the leads. 
     
     
         32 . The system of  claim 30  wherein said fitness computer component is configured to compute a fitness value that compares output of the forward model with actual detected impedance values. 
     
     
         33 . The system of  claim 30  wherein said fitness computer component is configured to compute a distance value expressing a difference between an output of the forward model and actual detected impedance values.