METHOD AND SYSTEM FOR CHARACTERIZING AND VISUALIZING ELECTROMAGNETIC TRACKING ERRORS

• US 20120323111A1
• Filed: 02/21/2011
• Published: 12/20/2012
• Est. Priority Date: 03/11/2010
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Chan, Raymond, Stanton, Douglas A., Jain, Ameet Kumar, Matinfar, Mohammad Babak, Parthasarthy, Vijay
• Granted Patent: US 9,165,114 B2
• Time in Patent Office: Days
• US Class Current: 600/411
• CPC Class Codes: A61B 2017/00119 alarm; indicating an abnormal situation
• CPC Class Codes: A61B 2034/2051 Electromagnetic tracking systems
• CPC Class Codes: A61B 34/20 Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
• CPC Class Codes: G16H 50/50 for simulation or modelling of medical disorders

Abstract

A calibration/surgical tool (90, 160) includes an electromagnetic sensor array (30) of two or more electromagnetic sensors in a known geometrical configuration. Electromagnetic tracking errors are characterized by a mapping of pre-operative absolute and relative errors based on a movement of a calibrated calibration/surgical tool (90, 160) through a pre-operative electromagnetic field. Using statistical mapping, a desired absolute error field (46) is measured either in the clinic as the part of daily quality control checks, or before the patient comes in or in vivo. A resulting error field (46) may be displayed to the physician to provide clear visual feedback about measurement confidence or reliability of localization estimates of the absolute errors in electromagnetic tracking.

Claims

1. An electromagnetic tracking system (200), comprising:

an electromagnetic sensor array (30) including at least two electromagnetic sensors arranged in a known geometrical configuration; and

a data processor (220) in electrical communication with the electromagnetic sensor array (30) to receive signals indicative of a sensing of an electromagnetic field by the electromagnetic sensors,

wherein the data processor (220) is operable to compute intra-operative relative errors (43) responsive to a movement of the electromagnetic sensor array (30) to numerous estimation positions within an intra-operative electromagnetic field,

wherein each intra-operative relative error (43) is an absolute differential between a calibrated distance (40) of an electromagnetic sensor pair and a sensed distance between the electromagnetic sensor pair within the intra-operative electromagnetic field,

wherein the data processor (220) is further operable to estimate intra-operative absolute errors (44) responsive to a plotting of the intra-operative relative errors (43) within a pre-operative error map (42) representative of a statistical relationship between pre-operative absolute errors (41) and pre-operative relative errors (41) derived from a movement of the electromagnetic sensor array (30) to numerous measurement positions within a pre-operative electromagnetic field,

wherein each intra-operative absolute error (44) is an absolute differential between an estimation position and a sensed position of an electromagnetic sensor within the intra-operative electromagnetic field,

wherein each pre-operative absolute error (41) is an absolute differential between a measurement position and a sensed position of an electromagnetic sensor within the pre-operative electromagnetic field, and

wherein each pre-operative relative error (41) is an absolute differential between a calibrated distance (40) and a sensed distance between an electromagnetic sensor pair within the pre-operative electromagnetic field.

2. The electromagnetic tracking system (200) of claim 1,

wherein the data processor (220) is operable to provide feedback representative of an estimation of the intra-operative absolute errors (44), and

wherein the feedback includes at least one of a visual feedback, an audio feedback and a tactile feedback.

3. The electromagnetic tracking system (200) of claim 2, further comprising:

an imaging system (203) in electrical communication with the data processor (220) to visually display the visual feedback.

4. The electromagnetic tracking system (200) of claim 1,

wherein the data processor (220) is further operable to generate an intra-operative absolute error field (46) responsive to an estimation of the intra-operative absolute errors (44),

wherein the intra-operative absolute error field (46) includes at least one of a reliable zone (24a) and an unreliable zone (24b),

wherein the reliable zone (24a) is indicative of an undistorted area of the intra-operative electromagnetic field, and

wherein the unreliable zone (24b) is indicative of a distorted area of the intra-operative electromagnetic field.

5. The electromagnetic tracking system (200) of claim 4, further comprising:

an imaging system (203) in electrical communication with the data processor (220) to integrate the intra-operative absolute error field (46) and an image of an object within the intra-operative electromagnetic field.

6. The electromagnetic tracking system (200) of claim 1,

wherein the data processor (220) is further operable to generate an intra-operative absolute error field (46) responsive to a comparison of a reliability threshold (45) to an estimation of the intra-operative absolute errors (44),

wherein the intra-operative absolute error field (46) including at least one of a reliable zone (24a) and an unreliable zone (24b),

wherein the reliable zone (24a) is indicative of an undistorted area of the intra-operative electromagnetic field, and

wherein the unreliable zone (24b) being indicative of a distorted area of the intra-operative electromagnetic field.

7. The electromagnetic tracking system (200) of claim 5, further comprising:

an imaging system (203) in electrical communication with the data processor (220) to visually display an integration of the intra-operative absolute error field (46) and an image of an object within the intra-operative electromagnetic field.

8. The electromagnetic tracking system (200) of claim 1, further comprising:

a calibration tool (90), wherein the electromagnetic sensor array (30) is incorporated in the calibration tool (90).

9. The electromagnetic tracking system (200) of claim 1, further comprising:

a surgical tool, wherein the electromagnetic sensor array (30) is incorporated in the surgical tool.

10. The electromagnetic tracking system (200) of claim 9,

wherein the surgical tool (160) includes a sheath (163);

and

wherein the electromagnetic sensor array (30) is patterned on an electronic substrate bonded to a surface of the sheath (163) and covered with a barrier coating.

11. The electromagnetic tracking system (200) of claim 9,

wherein the surgical tool includes a mandrin (170);

and

wherein the electromagnetic sensor array is patterned on an electronic substrate bonded to a surface of the mandarin (170) and covered with a barrier coating.

12. The electromagnetic tracking system (200) of claim 9,

wherein the surgical tool (90) includes a needle (170);

and

wherein the electromagnetic sensor array (30) is patterned on an electronic substrate bonded to a surface of the needle (170) and covered with a barrier coating.

13. The electromagnetic tracking system (200) of claim 9,

wherein the surgical tool includes a deflectable balloon (185);

and

wherein the electromagnetic sensor array is patterned on an electronic substrate bonded to a surface of the deflectable balloon (185) and covered with a barrier coating.

14. The electromagnetic tracking system (200) of claim 9,

wherein the surgical tool includes a mesh (192);

and

wherein the electromagnetic sensor array (30) is patterned on an electronic substrate bonded to a surface of the mesh (192) and covered with a barrier coating.

15. The electromagnetic tracking system (200) of claim 1, further comprising:

an electromagnetic field generator (202) operable to generate at least one of the pre-operative electromagnetic field and the intra-operative electromagnetic field.

16. An electromagnetic tracking method for a tool (90) including a known geometrical configuration of an electromagnetic sensor array (30) of two or more electromagnetic sensors, the method comprising:

a measurement of a calibrated distance (40) between at least one electromagnetic sensor pair responsive to the electromagnetic sensor array (30) being within a calibration electromagnetic field;

a controlled movement of the electromagnetic sensor array (30) within a pre-operative electromagnetic field to various measurement positions;

for each electromagnetic sensor, a measurement of a pre-operative absolute error (41) at each measurement position of the electromagnetic sensor, wherein each pre-operative absolute error (41) is an absolute differential between a measurement position and a sensed position of the electromagnetic sensor within the pre-operative electromagnetic field; and

for each pairing of electromagnetic sensors, a measurement of a pre-operative relative error (41) at each measurement position, wherein each pre-operative relative error (41) is an absolute differential between a calibrated distance (40) of an electromagnetic sensor paring and a sensed distance of the electromagnetic sensor pair within the pre-operative electromagnetic field.

17. The electromagnetic tracking method of claim 16, further comprising:

a generation of a pre-operative error map (42) derived from a statistical relationship between the pre-operative absolute errors (41) and the pre-operative relative errors (41).

18. The electromagnetic tracking method of claim 17, further comprising:

a controlled movement of the electromagnetic sensor array (30) within an intra-operative electromagnetic field to various estimation positions;

for each electromagnetic sensor pair, a measurement of an intra-operative relative error (43) at each estimation position, wherein each intra-operative relative error (43) is an absolute differential between a calibrated distance (40) of an electromagnetic sensor pair and a sensed distance of the electromagnetic sensor pair within the intra-operative electromagnetic field; and

for each estimation position, an estimation of an intra-operative absolute error (44) derived from a plotting of the intra-operative relative errors (43) within the pre-operative error map (42).

19. The electromagnetic tracking method of claim 18, further comprising:

a generation of feedback representative of an estimation of the intra-operative absolute errors (44), wherein the feedback includes at least one of a visual feedback, an audio feedback and a tactile feedback.

20. The electromagnetic tracking system (200) of claim 18, further comprising:

a generation of an intra-operative absolute error field (46) responsive to an estimation of the intra-operative absolute errors (44),

wherein the intra-operative absolute error field (46) includes at least one of a reliable zone (24a) and an unreliable zone (24b),

wherein the reliable zone (24a) is indicative an undistorted electromagnetic area of the intra-operative electromagnetic field, and

wherein the unreliable zone (24b) is indicative of a distorted electromagnetic area of the intra-operative electromagnetic field.