Mri-guided stereotactic surgery method

Abstract

A MRI-guided stereotactic surgery method including the following steps: assigning coordinates of a surgery target point of a surgery cannula and an insertion direction of the surgery cannula; performing coordinate transformation to transform the coordinates of the surgery target point into an insertion position of the surgery target point; substituting the insertion position and the insertion direction into an inverse kinematics model to obtain five parameters respectively corresponding to five degrees of freedom of a MRI-compatible stereotactic surgery device; controlling the MRI-compatible stereotactic surgery device according to the parameters to start a stereotactic surgery procedure, thereby inserting the surgery cannula; obtaining an actual cannula position according to a magnetic resonance (MR) image; comparing the actual cannula position with the surgery target point to obtain a position error vector; and withdrawing the surgery cannula to finish the stereotactic surgery procedure when the position error vector is acceptable.

What is claimed is: 
     
         1 . A MRI-guided stereotactic surgery method, comprising:
 assigning coordinates of a surgery target point of a surgery cannula and an insertion direction of the surgery cannula;   performing coordinate transformation to transform the coordinates of the surgery target point into an insertion position of the surgery target point;   substituting the insertion position and the insertion direction into an inverse kinematics model to obtain five parameters respectively corresponding to five degrees of freedom of a MRI-compatible stereotactic surgery device;   controlling the MRI-compatible stereotactic surgery device according to the parameters to start a stereotactic surgery procedure, thereby inserting the surgery cannula;   obtaining an actual cannula position according to a magnetic resonance (MR) image providing by a magnetic resonance imaging (MRI) scanner;   comparing the actual cannula position with the surgery target point to obtain a position error vector; and   withdrawing the surgery cannula to finish the stereotactic surgery procedure when the position error vector is acceptable.   
     
     
         2 . The MRI-guided stereotactic surgery method of  claim 1 , wherein when the position error vector is not acceptable, the MRI-guided stereotactic surgery method further comprises:
 calculating a compensation quantity according to the position error vector;   adjusting three of the parameters according to the compensation quantity;   controlling the MRI-compatible stereotactic surgery device according to the adjusted parameters, thereby withdrawing the surgery cannula, adjusting the insertion position and the insertion direction of the surgery cannula, and inserting the surgery cannula again;   updating the actual cannula position according to the MR image updating by the MRI scanner;   comparing the updated actual cannula position with the surgery target point to update the position error vector; and   withdrawing the surgery cannula to finish the stereotactic surgery procedure when the updated position error vector is acceptable.   
     
     
         3 . The MRI-guided stereotactic surgery method of  claim 2 , wherein the compensation quantity is calculated by a Taylor series expansion and by utilizing a Jacobian square matrix based on the position error vector. 
     
     
         4 . The MRI-guided stereotactic surgery method of  claim 1 , wherein the parameters are obtained by utilizing a Newton-Raphson iterative method. 
     
     
         5 . The MRI-guided stereotactic surgery method of  claim 1 , wherein the MRI-compatible stereotactic surgery device comprises a based plate, a horizontal arc-shaped slide fixed on the base plate and a horizontal sliding stage disposed on the horizontal arc-shaped slide, wherein the horizontal sliding stage comprises a first friction wheel in rolling friction contact with the horizontal arc-shaped slide, wherein the horizontal sliding stage moves along the horizontal arc-shaped slide in a first direction through the first friction wheel, wherein the first direction corresponds to a first degree of freedom of a MRI-compatible stereotactic surgery device, wherein the horizontal arc-shaped slide comprises a first driven wheel for recording relative movement between the first friction wheel and the horizontal arc-shaped slide, wherein the MRI-guided stereotactic surgery method further comprises:
 measuring amount of rotation of the first driven wheel by utilizing a first optical encoder connected to the first driven wheel, thereby recording relative movement between the first friction wheel and the horizontal arc-shaped slide.   
     
     
         6 . The MRI-guided stereotactic surgery method of  claim 5 , wherein the MRI-compatible stereotactic surgery device further comprises a vertical arc-shaped slide fixed on the horizontal sliding stage and a vertical sliding stage disposed on the vertical arc-shaped slide, wherein the vertical sliding stage comprises a second friction wheel in rolling friction contact with the vertical arc-shaped slide, wherein the vertical sliding stage moves along the vertical arc-shaped slide in a second direction through the second friction wheel, wherein the second direction corresponds to a second degree of freedom of a MRI-compatible stereotactic surgery device, wherein the vertical arc-shaped slide comprises a second driven wheel for recording relative movement between the second friction wheel and the vertical arc-shaped slide, wherein the MRI-guided stereotactic surgery method further comprises:
 measuring amount of rotation of the second driven wheel by utilizing a second optical encoder connected to the second driven wheel, thereby recording relative movement between the second friction wheel and the vertical arc-shaped slide.