Feature Tracking Using Ultrasound

• US 20110172526A1
• Filed: 11/30/2010
• Published: 07/14/2011
• Est. Priority Date: 01/12/2010
• Status: Abandoned Application

• Current Assignee: Elekta Ltd. (Elekta AB)
• Original Assignee: Elekta Ltd. (Elekta AB)
• Inventors: Lathuiliere, Fabienne, Falco, Tony, Lachaine, Martin, Tremblay, Sebastien
• Application Number:
  US12/956,991
• Publication Number:
  US 20110172526A1
• Time in Patent Office: Days
• US Class Current: 600/439
• CPC Class Codes: A61B 2034/2055 Optical tracking systems
• CPC Class Codes: A61B 2034/2063 Acoustic tracking systems, e.g. using ultrasound
• CPC Class Codes: A61B 2034/2065 Tracking using image or pattern recognition
• CPC Class Codes: A61B 2090/378 using ultrasound
• CPC Class Codes: A61B 34/20 Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
• CPC Class Codes: A61B 8/085 for locating body or organic structures, e.g. tumours, calculi, blood vessels, nodules
• CPC Class Codes: A61B 8/4245 involving determining the position of the probe, e.g. with respect to an external reference frame or to the patient
• CPC Class Codes: A61B 8/4263 using sensors not mounted on the probe, e.g. mounted on an external reference frame
• CPC Class Codes: A61B 8/4461 Features of the scanning mechanism, e.g. for moving the transducer within the housing of the probe
• CPC Class Codes: A61B 8/4472 Wireless probes
• CPC Class Codes: A61B 8/483 involving the acquisition of a 3D volume of data
• CPC Class Codes: A61B 8/54 Control of the diagnostic device
• CPC Class Codes: A61B 8/58 Testing, adjusting or calibrating the diagnostic device
• CPC Class Codes: A61B 8/587 Calibration phantoms models for medical purposes G09B23/28
• CPC Class Codes: A61N 2005/1058 using ultrasound imaging
• CPC Class Codes: A61N 2005/1074 Details of the control system, e.g. user interfaces
• CPC Class Codes: A61N 5/1049 for verifying the position of the patient with respect to the radiation beam
• CPC Class Codes: A61N 5/1067 in real time, i.e. during treatment
• CPC Class Codes: G06T 2207/10132 Ultrasound image
• CPC Class Codes: G06T 2207/10136 3D ultrasound image
• CPC Class Codes: G06T 2207/30004 : Biomedical image processing
• CPC Class Codes: G06T 7/0012 : Biomedical image inspection
• CPC Class Codes: G06T 7/251 : involving models

Abstract

Various implementations of the invention provide techniques and supporting systems that facilitate real-time or near-real-time ultrasound tracking for the purpose of calculating changes in anatomical features during a medical procedure. More specifically, anatomical features within a patient undergoing a medical procedure are tracked by obtaining temporally-distinct three dimensional ultrasound images that include the feature of interest and obtaining a targeted subset of ultrasound images focused on the feature. Based on the targeted subset of ultrasound images, a displacement of the feature is determined and image parameters used to obtain the targeted subset of ultrasound images are adjusted based on the displacement. This results in a time-based sequence of three dimensional images and targeted ultrasound images of the feature that identify changes in the position, size, location, and/or shape of the feature.

Claims

1. A computer-implemented method for tracking an anatomical feature of interest within a patient undergoing a medical procedure, the method comprising:

obtaining from a memory device a three dimensional image of a region of interest wherein the region of interest includes the feature of interest at a first periodicity;

determining a location of the feature of interest in the region of interest; and

by a processor, iteratively obtaining temporally-displaced targeted subsets of ultrasound images at a periodicity greater than the first periodicity focused on the determined location, each subset being compared with the three dimensional image and determining, based on each comparison, a displacement of the feature.

2. The method of claim 1 further comprising determining if the displacement exceeds a displacement threshold and if so, obtaining an updated three dimensional image of the region of interest sooner than would be obtained according to the first periodicity.

3. The method of claim 1 wherein the displacement threshold comprises an upper limit of spatial displacement of the feature of interest.

4. The method of claim 1 further comprising determining if the displacement exceeds a safety threshold and if so, halting the medical procedure to allow for one or more adjustments to the patient'"'"'s orientation with respect to a treatment device.

5. The method of claim 1 further comprising adjusting one or more image parameters used in obtaining the targeted subset of ultrasound images based on the displacement.

6. The method of claim 1 further comprising continuously adjusting one or more treatment apparatus in response to the displacement without interrupting the medical procedure.

7. The method of claim 6 wherein the treatment apparatus comprises one or more of a treatment couch and a multi-leaf collimator.

8. The method of claim 1 wherein the targeted subset comprises a series of two dimensional image slices of the feature.

9. The method of claim 1 wherein the targeted subset comprises two or more tracking planes.

10. The method of claim 9 wherein one or more of the tracking planes comprise reconstructed planes.

11. The method of claim 1 wherein the targeted subset further comprises three dimensional ultrasound datasets related to a limited region of interest.

12. The method of claim 11 wherein the limited reduced region of interest is based at least in part on an adjusted sector size.

13. The method of claim 11 wherein the limited reduced region of interest is based at least in part on an adjusted image depth.

14. The method of claim 11 wherein the limited reduced region of interest is based at least in part on an adjusted ultrasound sector angle.

15. The method of claim 1 wherein the targeted subset further comprises three dimensional ultrasound datasets having a reduced resolution.

16. The method of claim 1 wherein the three dimensional ultrasound images are obtained using a motorized probe.

17. The method of claim 1 wherein the three dimensional ultrasound images are obtained using a biplanar probe.

18. The method of claim 1 wherein the three dimensional ultrasound images are obtained using a matrix probe.

19. The method of claim 1 wherein the three dimensional ultrasound images are obtained using a three dimensional ultrasound probe placed external to the patient.

20. The method of claim 1 wherein the three dimensional ultrasound images are obtained using a three dimensional ultrasound probe placed internal to the patient.

21. The method of claim 1 wherein the medical procedure comprises external beam radiotherapy.

22. The method of claim 1 wherein the medical procedure comprises obtaining one or more planning images for radiotherapy.

23. The method of claim 1 wherein the feature comprises an organ.

24. The method of claim 1 further comprising segmenting a subset of the targeted images.

25. The method of claim 1 wherein the comparison comprises comparing grey-scale values of a subset of the targeted images.

26. The method of claim 1 wherein the targeted subset of ultrasound images are obtained using an ultrasound probe having trackable markers affixed thereto.

27. The method of claim 26 wherein the trackable markers are tracked over time using a tracking system.

28. The method of claim 26 wherein the trackable markers are calibrated to pixels within the targeted subset of ultrasound images.

29. The method of claim 1 wherein the feature comprises a prostate gland and the targeted subset of ultrasound images are obtained transperineally.

30. A system for tracking an anatomical feature of interest within a patient undergoing a medical procedure, the system comprising:

a processor configured to;

(i) locate the feature of interest within a series of three dimensional images of a region of interest obtained at a first periodicity wherein the region of interest includes the feature of interest, (ii) iteratively comparing temporally displaced targeted subsets of ultrasound images obtained at a periodicity greater than the first periodicity with the three dimensional image, and (iii) determining, based on each comparison, a displacement of the feature of interest; and

a register for receiving and storing the three dimensional image and the temporally displaced targeted subsets of ultrasound images.

31. The system of claim 30 wherein the processor is further configured to determine if the displacement exceeds a displacement threshold and if so, provide instructions to obtain an updated three dimensional image of the region of interest sooner than would be obtained based on the first periodicity.

32. The system of claim 31 wherein the displacement threshold comprises an upper limit of spatial displacement of the feature of interest.

33. The system of claim 30 wherein the processor is further configured to determine if the displacement exceeds a safety threshold and if so, provide instructions to halt the medical procedure to allow for one or more adjustments to the patient'"'"'s orientation with respect to a treatment device prior to reinstating the procedure.

34. The system of claim 30 further comprising an ultrasound probe for providing the images.

35. The system of claim 31 wherein the ultrasound probe comprises a two dimensional ultrasound probe and a housing into which the ultrasound probe is rotatably mounted, thereby providing at least one degree of freedom of movement of the probe within the housing.

36. The system of claim 35 further comprising a motor for causing the probe to oscillate within the housing according to the at least one degree of freedom.

37. The system of claim 31 wherein the ultrasound probe further comprises trackable markers affixed thereto.

38. The system of claim 31 further comprising a controller for providing the adjusted imaging parameters to the ultrasound probe.

39. The system of claim 30 further comprising a display for displaying the images.