Robotically assisted medical ultrasound

• US 6,425,865 B1
• Filed: 06/11/1999
• Issued: 07/30/2002
• Est. Priority Date: 06/12/1998
• Status: Expired due to Fees

• Current Assignee: British Columbia Cancer Agency Branch (Province of British Columbia), University of British Columbia
• Original Assignee: University of British Columbia
• Inventors: Bell, Graham S., Jameson, Michael, Salcudean, Septimiu E., Lawrence, Peter D., Marko, Alexei
• Primary Examiner(s): Lateef, Marvin M.
• Assistant Examiner(s): PATEL, MAULIN M
• Application Number:
  US09/330,598
• Time in Patent Office: 1,145 Days
• Field of Search: 600/439, 600/437, 600/111, 600/438, 378/117, 606/1
• US Class Current: 600/437
• CPC Class Codes: A61B 2090/064 for measuring force, pressure or mechanical tension
• CPC Class Codes: A61B 2090/066 for measuring torque
• CPC Class Codes: A61B 2090/506 using a parallelogram linkage, e.g. panthograph
• CPC Class Codes: A61B 34/30 Surgical robots
• CPC Class Codes: A61B 34/32 operating autonomously
• CPC Class Codes: A61B 34/37 Master-slave robots A61B34/35 takes precedence
• CPC Class Codes: A61B 34/77 Manipulators with motion or force scaling
• CPC Class Codes: A61B 8/06 Measuring blood flow measuring volume flow in general G01F, e.g. G01F1/66, G01F1/72; measuring speed of fluids in general G01P5/00
• CPC Class Codes: A61B 8/0875 for diagnosis of bone A61B5/4504 takes precedence
• CPC Class Codes: A61B 8/4218 characterised by articulated arms
• 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

Abstract

A system for medical ultrasound in which the ultrasound probe is positioned by a robot arm under the shared control of the ultrasound operator and the computer is proposed. The system comprises a robot arm design suitable for diagnostic ultrasound, a passive or active hand-controller, and a computer system to co-ordinate the motion and forces of the robot and hand-controller as a function of operator input, sensed parameters and ultrasound images.

Claims

1. A method of positioning an ultrasound transducer onto the surface of a human body comprising:

mechanically positioning the ultrasound transducer on the surface of the human body by an operator positioned remotely from the ultrasound transducer operating a hand controller which is linked to the ultrasound transducer and which by means of a programmed computer instructs and causes the ultrasound transducer to be positioned on the surface on the human body, the ultrasound transducer acquiring and transmitting ultrasound images to a display viewed by the operator, said computer being programmed to prevent an above threshold level normal force being exerted on the human body.

2. A method as claimed in claim 1 wherein the hand controller controls electronically and remotely the position of the ultrasound transducer on the human body.

3. A method as claimed in claim 1 wherein the hand controller controls electronically and remotely the velocity of the ultrasound transducer over the human body.

4. A method as claimed in claim 1 wherein the hand controller controls electronically and remotely the force exerted by the ultrasound transducer on the human body.

5. A method as claimed in claim 1 wherein the hand controller controls electronically and remotely a combination of velocity and force of the ultrasound transducer on the human body.

6. A method as claimed in claim 1 wherein the hand controller controls only some of the degrees of freedom available to the ultrasound transducer and a control computer controls the others.

7. A method as claimed in claim 1 wherein the computer is programmed to hold the ultrasound transducer at a fixed position on the human body, and the operator controls the orientation of the ultrasound transducer.

8. A method as claimed in claim 1 wherein the force exerted by the transducer is controlled by the computer according to a force sensor reading and the operator is permitted to control orientation of the ultrasound transducer.

9. A method as claimed in claim 1 wherein normal force exerted by the transducer is controlled by the computer but the orientation of the ultrasound transducer is adjusted to a stated program value in the computer.

10. A method as claimed in claim 1 wherein the connection between the positioning of the ultrasound transducer and the operator and the hand controller is performed by means of a counterbalanced robot.

11. A method as claimed in claim 10 wherein the program in the computer controls certain degrees of freedom and the counterbalanced robot controls other degrees of freedom.

12. A method of performing an ultrasound examination on a person comprising using a robot arm to position an ultrasound probe on the surface of the person according to shared control of a remotely positioned ultrasound operator and a programmed computer, the ultrasound probe acquiring and transmitting ultrasound images in real time to a display viewed by the operator, said shared control incorporating a method to prevent an above threshold level force being exerted on the person.

13. A method according to claim 12 wherein the ultrasound transducer probe information is displayed on the monitor, and the operator activates the hand controller to regulate the force applied by the ultrasound transducer probe on the surface of the human body.

14. A method as claimed in claim 12 wherein the operator controls motion of the ultrasound transducer probe along certain degrees of freedom and the programmed computer controls the motion of the ultrasound transducer probe along other degrees of freedom.

15. A method as claimed in claim 12 wherein the computer is programmed to recall trajectories followed by the ultrasound transducer probe during a prior ultrasound scan of the human body.

16. A method as claimed in claim 12 wherein the computer is programmed to recall serial positions and serial forces applied by the ultrasound transducer probe during a prior serial position and serial force trajectory followed by the ultrasound transducer probe on the human body.

17. A method as claimed in claim 12 wherein the computer is programmed to repeat scans of the ultrasound transducer probe from different incremental positions on the human body lateral to the scan direction and rationalizes the repeated scans to generate a three-dimensional ultrasound image on the monitor.

18. A method according to claim 12 wherein the computer is programmed to perform mixed modes of operation wherein the operator shares control of the position of the ultrasound transducer probe along certain axes with taught control programmed into the computer and a tracking mode along a plane is programmed in the computer while the operator controls the movement of the ultrasound transducer probe along the remaining degrees of freedom.

19. A method according to claim 12 wherein control of the position, force or velocity of the ultrasound transducer is shared between the operator and the computer and determined according to the ultrasound image.

20. A method as claimed in claim 12 wherein the operator uses an input device to input a component of motion control to the transducer to scan new parts of the human body and to input a component of orientation control to the transducer while observing the ultrasound images generated by the ultrasound image monitor to maximize image signal-to-noise ratio.

21. A method as claimed in claim 12 wherein ultrasound image features are processed by the computer to determine the optimum orientation of the transducer and provide an automatic orientation control signal component which is added to the attitude control input from the operator'"'"'s input device.

22. A method as claimed in claim 12 wherein the transducer image features are processed by the computer to provide an automatic direction control signal component which tracks relevant anatomical structures under the surface of the skin of the human body.

23. A method as claimed in claim 12 wherein the computer senses the force vector applied by the operator to the input device and scales said force up or down and adds it to a predetermined force applied between the transducer and the human body.

24. A method as claimed in claim 12 wherein the input device is capable of displaying a force vector to the operator that is computed by the computer based scaling the actual force observed at the probe/skin interface of the human body.

25. A method as claimed in claim 12 wherein the direction of motion of the transducer is determined from a recording of a previous scan.

26. A method as claimed in claim 12 wherein the hand controller is a joy stick which provides force feedback to the operator.

27. An apparatus for positioning an ultrasound transducer onto a human body comprising:

(a) a mechanism to position the ultrasound transducer on the human body;

(b) a hand controller to enable an operator to input into a computer a desired position, a desired velocity or a desired force, or a linear combination thereof; and

(c) a computer control that maps the operator input into the ultrasound transducer position, velocity or force, said computer being programmed to prevent an above threshold level normal force being exerted by the ultrasound transducer on the human body.

28. An apparatus as claimed in claim 27 wherein the hand controller controls the position of the transducer.

29. An apparatus as claimed in claim 27 wherein the hand controller controls the velocity of the transducer.

30. An apparatus as claimed in claim 27 wherein the hand controller controls the force of the transducer.

31. An apparatus as claimed in claim 27 wherein the hand controller controls a linear combination of velocity and force of the transducer.

32. An apparatus as claimed in claim 27 wherein the hand controller is a 6 degrees of freedom joy stick which provides force-feedback to an operator of the apparatus.

33. An apparatus as claimed in claim 32 wherein the joy stick controls only some of the degrees of freedom of the transducer.

34. An apparatus as claimed in claim 27 wherein the mechanism is a counterbalanced robot.

35. An apparatus as claimed in claim 34 wherein the robot has a 4-bar parallelogram linkage wrist.

36. An apparatus as claimed in claim 27 including a 6 degrees of freedom rate control device.

41. An apparatus as claimed in claim 27 wherein said computer control is programmed to enable free motion of the ultrasound transducer in relation to position and velocity but restricting force of the ultrasound transducer along directions constrained by the human body.

42. An apparatus as claimed in claim 27 wherein the apparatus includes a mechanism that breaks away when a normal force above a prescribed limit is exerted on the human body.

37. An apparatus for performing ultrasound on a person comprising:

(a) a 4-bar parallelogram linkage wrist robot arm with an ultrasound transducer for positioning the transducer on the surface of the body of the person;

(b) a passive or active hand controller which is operated by an operator to instruct the robot arm to position the ultrasound transducer on the surface of the body of the person; and

(c) a computer which is programmed to coordinate motion and force of the robot and hand controller as a function of operator input, sensed parameters and ultrasound images.

38. An apparatus as claimed in claim 37 wherein the operator controls the apparatus in a master-slave mode, and the robot tracks operator position, velocity or force.

39. An apparatus as claimed in claim 37 wherein the hand controller is passive.

40. An apparatus as claimed in claim 37 wherein the hand controller is active.

43. An apparatus as claimed in claim 37 including a monitor, wherein ultrasound transducer probe information is displayed on the monitor in real time, and the operator activates the hand controller to regulate the normal force applied by the ultrasound transducer probe on the surface of the human body.