Filtering method for surface modeling

Abstract

A system for mapping a tissue surface includes a probe for mapping a tissue surface, a localization system to measure a location data point indicative of the probe's location, a memory in which to store the location data point, a servo mechanism to move the probe along at least a portion of the tissue surface, a controller to move the probe to a plurality of locations and to record in the memory a plurality of location data points, and a contact-sensing processor to analyze the plurality of location data points and to identify a subset thereof on the tissue surface. A modeling processor generates a model of the tissue surface using the subset of location data points. The contact-sensing processor utilizes probe velocity, or a rate of change in the distance moved by the probe, to determine contact between the probe and the tissue surface.

1 . (canceled) 
     
     
         2 . A method of mapping a portion of an anatomy, comprising:
 measuring a first location of a medical device within the portion of the anatomy at a first time;   measuring a second location of the medical device within the portion of the anatomy at a second time;   determining a velocity of the medical device from the first location of the medical device at the first time and the second location of the medical device at the second time; and   updating a map of the portion of the anatomy if the velocity of the medical device falls below a preset velocity threshold.   
     
     
         3 . The method according to  claim 2 , wherein updating a map of the portion of the anatomy if the velocity of the medical device falls below a preset velocity threshold comprises updating the map of the portion of the anatomy if the velocity of the medical device continuously falls below the preset velocity threshold for a preset amount of time. 
     
     
         4 . The method according to  claim 2 , wherein the map of the portion of the anatomy comprises a geometry of the portion of the anatomy. 
     
     
         5 . A method for performing a medical procedure, comprising:
 tracking a position of a probe inserted into a body of a patient;   assessing at least one stability parameter associated with a position of the probe relative to a tissue surface of an organ using a rate of change in the position of the probe over time; and   updating a map of the tissue surface responsive to the at least one assessed stability parameter.   
     
     
         6 . The method according to  claim 5 , wherein the at least one assessed stability parameter comprises an assessed stability of contact between the probe and the tissue surface. 
     
     
         7 . The method according to  claim 6 , wherein the stability of contact between the probe and the tissue surface is assessed by:
 determining the rate of change in the position of the probe over time;   establishing a rate of change threshold; and   comparing the rate of change in the position of the probe over time to the rate of change threshold.   
     
     
         8 . The method according to  claim 7 , wherein updating a map of the tissue surface of the organ responsive to the at least one assessed stability parameter comprises updating the map of the tissue surface of the organ when the rate of change in the position of the probe over time is below the rate of change threshold. 
     
     
         9 . The method according to  claim 7 , wherein the stability of contact between the probe and the tissue surface of the organ is further assessed by establishing a lockout duration. 
     
     
         10 . The method according to  claim 9 , wherein updating a map of the tissue surface of the organ responsive to the at least one assessed stability parameter comprises updating the map of the tissue surface of the organ when the rate of change in the position of the probe over time is below the rate of change threshold for a continuous period of at least the lockout duration. 
     
     
         11 . The method according to  claim 6 , wherein updating the map of the tissue surface is performed automatically by a modeling processor configured to assess the stability of contact between the probe and the tissue surface. 
     
     
         12 . The method according to  claim 5 , wherein the map of the tissue surface of the organ comprises a geometric model of the tissue surface. 
     
     
         13 . The method according to  claim 5 , wherein assessing at least one stability parameter associated with a position of the probe comprises:
 determining a first position of the probe relative to the tissue surface at a first time;   determining a second position of the probe relative to the tissue surface at a second time subsequent to the first time;   determining a distance between the first position of the probe and the second position of the probe;   establishing a distance threshold; and   comparing the distance between the first position of the probe and the second position of the probe to the distance threshold.   
     
     
         14 . Apparatus for performing a medical procedure, comprising:
 a processor, which is configured to receive inputs from a probe that is configured to be brought into contact with a tissue surface of an organ in a body of a patient, wherein the processor is further configured:
 to track a position of the probe within the body of the patient; 
 to assess a stability of the contact between the probe and the tissue surface of the organ based using a plurality of measurements of the position of the probe within the body of the patient; and 
 to update a map of the tissue surface of the organ responsively to the assessed stability of the contact between the probe and the tissue surface of the organ. 
   
     
     
         15 . The apparatus according to  claim 14 , wherein the processor is configured to:
 compute a velocity of the probe from the plurality of measurements of the position of the probe within the body of the patient;   accept a definition of a velocity threshold; and   update the map of the tissue surface of the organ when the velocity of the probe is less than the velocity threshold.   
     
     
         16 . The apparatus according to  claim 15 , wherein the processor is further configured to accept definition of a lockout interval. 
     
     
         17 . The apparatus according to  claim 16 , wherein the processor is configured to update the map of the tissue surface of the organ when the velocity of the probe is less than the velocity threshold for a continuous duration of at least the lockout interval. 
     
     
         18 . The apparatus according to  claim 14 , wherein the processor is configured to:
 measure a first position of the probe within the body of the patient at a first time;   measure a second position of the probe within the body of the patient at a second time;   compute a distance traveled by the probe between the first time and the second time;   accept a definition of a distance threshold; and   update the map of the tissue surface of the organ when the distance traveled by the probe between the first time and the second time is less than the distance threshold.   
     
     
         19 . The apparatus according to  claim 14 , wherein the map of the tissue surface of the organ comprises a geometric model of the tissue surface of the organ.