Systems and method for determining the shape of a surgical instrument and surgical instruments having a deformable body
A system and method for determining the spatial position and the shape of a surgical instrument ( 1 ) having a deformable body ( 2 ) by: providing an elasticity model of the surgical instrument ( 1 ); defining at least one parameter which influences the shape of the instrument ( 1 ); determining the spatial position and/or orientation of at least one tracking sensor ( 3 ) of the surgical instrument ( 1 ); determining the value of the at least one parameter; calculating the position and/or orientation of at least one part of the surgical instrument ( 1 ) with the aid of the elasticity model together with the determined value of the at least one parameter and the determined spatial position and/or orientation of the at least one tracking sensor ( 3 ). The present invention also relates to a surgical instrument ( 1 ) having a deformable body ( 2 ) comprising at least two sensors ( 3, 4 ), wherein at least one sensor is a tracking sensor ( 3 ) and at least one other sensor is a sensor ( 4 ) which allows the value of a predetermined parameter influences the shape of the instrument ( 1 ) to be determined.
1. A method in a system including a processor and a memory device operatively coupled with the processor for determining the spatial position and the shape of an elongated deformable body of an associated surgical instrument, the method comprising:
storing a predefined elasticity model of the elongated deformable body in the memory device, wherein the predefined elasticity model describes deformation of the elongated deformable body of the associated surgical instrument as a function of:
a spatial position and orientation of a tip of the elongated deformable body of the associated surgical instrument; and
an influence on the elongated deformable body of the associated surgical instrument by at least one parameter;
determining by a tracking sensor disposed at the tip of the deformable body of the associated surgical instrument, a measured spatial position and orientation of the tip of the elongated deformable body;
determining the at least one parameter by a physical parameter sensor operatively coupled with the associated surgical instrument; and
executing logic stored in the memory device to calculate the spatial position and the shape of an elongated deformable body of an associated surgical instrument based on applying: i) the at least one parameter determined by the physical parameter sensor; and ii) the measured spatial position and orientation of the tip of the elongated deformable body determined by the tracking sensor to the predefined elasticity model of the elongated deformable body in the memory device.
2. The method according to claim 1 , wherein the determining the measured spatial position and orientation of the tip of the elongated deformable body comprises:
determining the measured spatial position and orientation of the tip of the elongated deformable body by a tracking sensor disposed at the tip of the deformable body of the associated surgical instrument.
3. The method according to claim 2 , wherein the determining the measured spatial position and orientation of the tip of the elongated deformable body comprises:
determining the measured spatial position and orientation of the tip of the elongated deformable body by an electromagnetic (EM) tracking sensor tracking sensor disposed at the tip of the deformable body of the associated surgical instrument.
4. The method according to claim 3 , wherein the determining the measured spatial position and orientation of the tip of the elongated deformable body comprises:
determining the measured spatial position and orientation of the tip of the elongated deformable body by the EM tracking sensor using an EM tracking method.
5. The method according to claim 1 , wherein the determining the at least one parameter comprises one or more of:
determining as the at least one parameter a relative distance difference between a first portion of the deformable body on an outer side of a bend and a second portion of the deformable body opposite the first portion on the inner side of the bend by one or more distance sensors;
determining as the at least one parameter a force applied to the tip of the elongate body relative to a proximal portion of the body by a force sensor;
determining as the at least one parameter a pressure applied to the tip of the elongate body relative to a proximal portion of the body by a pressure sensor; and/or
determining as the at least one parameter a stress applied to the tip of the elongate body relative to a proximal portion of the body by a force sensor.
6. The method according to claim 1 , wherein the determining the measured spatial position and orientation of the tip of the elongated deformable body comprises:
determining the measured spatial position and orientation of the tip of the elongated deformable body relative to the mid-proximal location of the elongated deformable body by determining a distance between a first tracking sensor disposed at the tip of the deformable body of the associated surgical instrument and a second tracking sensor disposed at the mid-proximal location of the elongated deformable body.
7. The method according to claim 1 , wherein the elasticity model is over-determined by inputting the determined value of the at least one predetermined parameter and the determined spatial position and orientation of the tracking sensor.
8. The method according to claim 1 wherein the executing the logic stored in the memory device to calculate the spatial position and the shape of the elongated deformable body of the associated surgical instrument comprises:
executing finite element logic stored in the memory device to use a finite element method to calculate the spatial position and the shape of an elongated deformable body of an associated surgical instrument.
9. The method according to claim 1 , wherein the determining the at least one parameter comprises:
determining the at least one parameter by measuring a length of a pull-wire of a catheter which is pulled out of the proximal end of the catheter in order to change the shape of the catheter body so as to obtain information on the extent to which a deformable part of the catheter body will deform.
10. The method according to claim 1 , wherein storing a predefined elasticity model of the elongated deformable body in the memory device comprises:
acquiring a predefined elasticity model having a form comprising a running parameter t of:
(
x
;
y
)
(
t
)
=
(
s
α
(
1
-
cos
t
)
;
s
α
sin
t
)
mit
t
∈
[
0
;
α
]
wherein:
the tracking sensor and the physical parameter sensor lie in a plane z=0 of an x, y, z, orthogonal coordinate space,
the tracking sensor is in the coordinate origin and an axis of the physical parameter sensor is along the y axis of the x, y, z, orthogonal coordinate space,
a portion of the associated surgical instrument between the tip of the elongated deformable body and the mid-proximal location of the elongated deformable body describes a circular section having a length s,
an exact shape of the elongated deformable body of the associated surgical instrument is described as a parameterized curve with a form parameter α∈├]0,2π] and with the running parameter t.
11. A surgical instrument comprising:
an elongate flexible body;
tracking sensor disposed at a tip of the deformable body, the tracking sensor determining a measured spatial position and orientation of the tip of the elongate flexible body; and
a physical parameter sensor operatively coupled with the elongate flexible body, the physical parameter sensor determining at least one parameter of the elongate flexible body of the surgical instrument,
wherein the spatial position and/or shape of the elongate flexible body is determinable using a predefined elasticity model of the elongate flexible body, wherein the predefined elasticity model describes deformation of the elongate flexible body of the surgical instrument as a function of:
the measured spatial position and orientation of the tip of the elongated deformable body; and
an influence on the elongate flexible body of the surgical instrument by the at least one parameter of the elongate flexible body of the surgical instrument.
12. The surgical instrument according to claim 11 , wherein:
the tracking sensor comprises an electromagnetic (EM) tracking sensor disposed at the tip of the elongate flexible body, the EM tracking sensor determining the measured spatial position and orientation of the tip of the elongate flexible body.
13. The surgical instrument according to claim 12 , wherein:
the physical parameter sensor comprises one or more of:
a distance sensor determining as the at least one parameter a relative distance difference between a first portion of the elongate flexible body on an outer side of a bend and a second portion of the elongate flexible body opposite the first portion on the inner side of the bend;
a force sensor determining as the at least one parameter a force applied to the tip of the elongate flexible body relative to a proximal portion of the elongate flexible body;
a pressure sensor determining as the at least one parameter a pressure applied to the tip of the elongate flexible body relative to a proximal portion of the elongate flexible body; and/or
a force sensor determining as the at least one parameter a stress applied to the tip of the elongate flexible body relative to a proximal portion of the elongate flexible body.
14. The surgical instrument according to claim 11 , wherein:
the physical parameter sensor comprises one or more of:
a distance sensor determining as the at least one parameter a relative distance difference between a first portion of the elongate flexible body on an outer side of a bend and a second portion of the elongate flexible body opposite the first portion on the inner side of the bend;
a force sensor determining as the at least one parameter a force applied to the tip of the elongate flexible body relative to a proximal portion of the elongate flexible body;
a pressure sensor determining as the at least one parameter a pressure applied to the tip of the elongate flexible body relative to a proximal portion of the elongate flexible body; and/or
a stress sensor determining as the at least one parameter a stress applied to the tip of the elongate flexible body relative to a proximal portion of the elongate flexible body.
15. The surgical instrument according to claim 11 , further comprising:
a pull-wire that is pullable from a proximal end of the surgical instrument in order to change the shape of the elongate flexible body,
wherein the physical parameter sensor comprises a distance sensor determining a length of the pull-wire pulled from the proximal end of the surgical instrument as the at least one parameter.
16. The surgical instrument according to claim 11 , further comprising:
a pull-wire that is pullable from a proximal end of the surgical instrument in order to change the shape of the elongate flexible body,
wherein the physical parameter sensor comprises a force sensor determining a forced used on the pull-wire as the at least one parameter.
17. The surgical instrument according to claim 11 , wherein the predefined elasticity model describes the deformation of the elongate flexible body of the surgical instrument as a function of the measured spatial position and orientation of the tip of the elongate flexible body and the influence on the elongate flexible body of the surgical instrument by the at least one parameter of the elongate flexible body of the surgical instrument, and having a form comprising a running parameter t of:
(
x
;
y
)
(
t
)
=
(
s
α
(
1
-
cos
t
)
;
s
α
sin
t
)
mit
t
∈
[
0
;
α
]
wherein:
the tracking sensor and the physical parameter sensor lie in a plane z=0 of an x, y, z, orthogonal coordinate space,
the tracking sensor is in the coordinate origin and an axis of the physical parameter sensor is along the y axis of the x, y, z, orthogonal coordinate space,
a portion of the associated surgical instrument between the tip of the elongate flexible body and the mid-proximal location of the elongate flexible body describes a circular section having a length s,
an exact shape of the elongate flexible body of the associated surgical instrument is described as a parameterized curve with a form parameter α∈├]0,2π] and with the running parameter t.
18. A system comprising:
a surgical instrument comprising an elongate flexible body;
a tracking sensor disposed at a tip of the elongate flexible body, the tracking sensor determining a measured spatial position and orientation of the tip of the elongate flexible body;
a physical parameter sensor operatively coupled with the elongate flexible body, the physical parameter sensor determining at least one parameter of the elongate flexible body of the surgical instrument;
a processor;
a memory device operatively coupled with the processor;
a predefined elasticity model of the elongate flexible body stored in the memory device, wherein the predefined elasticity model describes deformation of the elongate flexible body of the associated surgical instrument as a function of:
a spatial position and orientation of a tip of the elongate flexible body of the associated surgical instrument; and
an influence on the elongate flexible body of the associated surgical instrument by at least one parameter; and
logic stored in the memory device, the logic being executable by the processor to calculate the spatial position and the shape of an elongate flexible body of an associated surgical instrument based on applying: i) the at least one parameter determined by the physical parameter sensor; and ii) the measured spatial position and orientation of the tip of the elongate flexible body determined by the tracking sensor to the predefined elasticity model of the elongate flexible body in the memory device.
19. The system according to claim 18 , wherein:
the tracking sensor comprises an electromagnetic (EM) tracking sensor disposed at the tip of the elongate flexible body, the EM tracking sensor determining the measured spatial position and orientation of the tip of the elongate flexible body; and
the physical parameter sensor comprises one or more of:
a distance sensor determining as the at least one parameter a relative distance difference between a first portion of the elongate flexible body on an outer side of a bend and a second portion of the elongate flexible body opposite the first portion on the inner side of the bend;
a force sensor determining as the at least one parameter a force applied to the tip of the elongate flexible body relative to a proximal portion of the elongate flexible body;
a pressure sensor determining as the at least one parameter a pressure applied to the tip of the elongate flexible body relative to a proximal portion of the elongate flexible body; and/or
a force sensor determining as the at least one parameter a stress applied to the tip of the elongate flexible body relative to a proximal portion of the elongate flexible body.
20. The system according to claim 18 , wherein the logic is executable by the processor to apply the predefined elasticity model having a form comprising a running parameter t of:
(
x
;
y
)
(
t
)
=
(
s
α
(
1
-
cos
t
)
;
s
α
sin
t
)
mit
t
∈
[
0
;
α
]
wherein:
the tracking sensor and the physical parameter sensor lie in a plane z=0 of an x, y, z, orthogonal coordinate space,
the tracking sensor is in the coordinate origin and an axis of the physical parameter sensor is along the y axis of the x, y, z, orthogonal coordinate space,
a portion of the associated surgical instrument between the tip of the elongate flexible body and the mid-proximal location of the elongate flexible body describes a circular section having a length s,
an exact shape of the elongate flexible body of the associated surgical instrument is described as a parameterized curve with a form parameter α∈├]0,2π] and with the running parameter t.