Path planning and collision avoidance for movement of instruments in a radiation therapy environment

• US 20050281374A1
• Filed: 08/12/2004
• Published: 12/22/2005
• Est. Priority Date: 08/12/2003
• Status: Active Grant

• Current Assignee: LOMA Linda University Medical Center (Mission Healthcare Services LLC)
• Original Assignee: LOMA Linda University Medical Center (Mission Healthcare Services LLC)
• Inventors: Moyers, Michael F., Lesyna, David A., Cheng, Chieh C.
• Granted Patent: US 7,280,633 B2
• Time in Patent Office: Days
• US Class Current: 378/68
• CPC Class Codes: A61B 2090/3937 Visible markers
• CPC Class Codes: A61B 6/0442 made of non-metallic materials
• CPC Class Codes: A61B 6/4092 for producing synchrotron radiation
• CPC Class Codes: A61N 2005/105 using a laser alignment system
• CPC Class Codes: A61N 2005/1059 using cameras imaging the patient
• CPC Class Codes: A61N 2005/1061 using an x-ray imaging system having a separate imaging source
• CPC Class Codes: A61N 2005/1062 using virtual X-ray images, e.g. digitally reconstructed radiographs [DRR]
• CPC Class Codes: A61N 2005/1087 Ions; Protons
• CPC Class Codes: A61N 2005/1097 Means for immobilizing the patient
• 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: A61N 5/1069 Target adjustment, e.g. moving the patient support
• CPC Class Codes: A61N 5/1078 Fixed beam systems
• CPC Class Codes: B25J 9/1666 Avoiding collision or forbidden zones
• CPC Class Codes: G05B 15/02 electric
• CPC Class Codes: G05B 2219/45117 Medical, radio surgery manipulator

Abstract

A patient positioning system for use with a radiation therapy system that monitors the location of fixed and movable components and pre-plans movement of the movable components so as to inhibit movement if a collision would be indicated. The positioning system can also coordinate movement of multiple movable components for reduced overall latency in registering a patient. The positioning system includes external measurement devices which measure the location and orientation of objects, including components of the radiation therapy system, in space and can also monitor for intrusion into the active area of the therapy system by personnel or foreign objects to improve operational safety of the radiation therapy system.

Claims

1. A radiation therapy delivery system having fixed and movable components, the system comprising:

a gantry;

a patient pod configured to secure a patient substantially immobile with respect to the patient pod;

a patient positioner interconnected to the patient pod so as to position the patient pod along multiple translational and rotational axes within the gantry;

a radiation therapy nozzle interconnected to the gantry and selectively delivering radiation therapy along a beam axis;

a plurality of external measurement devices which obtain position measurements of at least the patient pod and nozzle; and

a controller which receives the position measurements of at least the patient pod and nozzle and determines movement commands to position the patient in a desired pose with respect to the beam axis and corresponding movement trajectories of the patient pod with respect to other fixed and movable components of the therapy delivery system based upon the movement commands and determines whether a collision is indicated for the movement commands and inhibits movement if a collision would be indicated.

2. The system of claim 1, wherein the external measurement devices obtain optical images of at least the patient pod and nozzle to obtain the position measurements.

3. The system of claim 1, further comprising a plurality of markers fixed to at least the patient pod and nozzle wherein the external measurement devices obtain position measurements of the markers.

4. The system of claim 1, further comprising at least one local position feedback device in operative communication with at least one of the gantry and patient positioner wherein the at least one local position feedback device provides position data to the controller indicative of the position of the at least one of the gantry and patient positioner.

5. The system of claim 1, further comprising a patient imaging system which is movable into the beam axis to obtain an image of the patient and out of the beam axis to reduce exposure of the imaging system to the radiation beam and wherein the system determines the relative location of a patient target isocenter with respect to the nozzle.

6. The system of claim 5, wherein the system positions the patient in an initial position and, after imaging the patient, determines a correction vector and corresponding movement commands and trajectories to move the patient positioner and the patient target isocenter into a desired pose with respect to the nozzle and evaluates the movement trajectories and inhibits movement if a collision is indicated.

7. The system of claim 1, wherein obtaining position measurements and providing the movement commands to the patient positioner is performed iteratively.

8. The system of claim 1, wherein the nozzle is interconnected to the gantry so as to be revolvable about a gantry isocenter.

9. The system of claim 8, wherein the system determines movement commands for both the patient positioner and the gantry to position the patient in a desired pose with respect to the beam axis and corresponding movement trajectories with respect to other fixed and movable components of the therapy delivery system and the gantry and patient positioner respectively based upon the movement commands and determines whether a collision is indicated for the movement commands and inhibits movement if a collision would be indicated.

10. The system of claim 9, wherein the system determines the movement commands and corresponding trajectories for simultaneous movement of the patient positioner and gantry to increase speed of acquisition of the desired pose.

11. The system of claim 1, wherein the external measurement devices also monitor for objects that may enter the determined movement trajectories and inhibits motion if any collision with such objects is indicated.

12. A path planning and collision avoidance system for a radiation therapy system having fixed and movable components and selectively delivering a radiation therapy beam along a beam axis, the positioning system comprising:

a plurality of external measurement devices arranged to obtain position measurements of the components so as to provide location information;

a movable patient support configured to support a patient substantially fixed in position with respect to the patient support and controllably position the patient in multiple translational and rotational axes; and

a controller receiving position information from the plurality of external measurement devices and providing movement commands to the movable patient support to automatically align the patient in a desired pose and determining a corresponding movement envelope wherein the controller evaluates the movement envelope and inhibits movement of the patient support if a collision is indicated else initiates the movement.

13. The path planning and collision avoidance system of claim 12, wherein aligning the patient in the desired pose comprises aligning the patient support with respect to a beam delivery aiming point through which the radiation therapy system directs a radiation beam.

14. The path planning and collision avoidance system of claim 12, further comprising a patient imager system which is movable into and out of the beam axis so as to obtain an image of the patient and a target iso-center, wherein the path planning and collision avoidance system determines movement commands and trajectories for both the patient imager and the patient support and inhibits movement if a collision is indicated.

15. The path planning and collision avoidance system of claim 12, further comprising a plurality of markers fixed to selected points of the plurality of the components subject to movement and wherein the external measurement devices obtain position measurements of the markers.

16. The path planning and collision avoidance system of claim 15, wherein multiple external measurement devices obtain position measurements of a single marker so as to provide a more accurate measurement of the single marker'"'"'s location than provided by a single external measurement device.

17. The path planning and collision avoidance system of claim 12, wherein the external measurement devices also monitor for objects that may enter the determined movement trajectories and wherein the controller inhibits motion if any collision with such objects is indicated

18. A method of registering and positioning a patient for delivery of therapy with a system having fixed and at least one movable components, the method comprising the steps of:

positioning a patient in an initial treatment pose with a controllable patient positioner;

externally measuring the location of selected points of the fixed and at least one movable components;

determining a difference vector between the observed initial patient pose and a desired patient pose;

determining corresponding movement commands and a movement trajectory for the patient positioner to bring the patient to the desired patient pose; and

comparing the movement trajectory with the measured locations of the selected points of the fixed and at least one movable components so as to inhibit movement of the patient positioner if a collision is indicated.

19. The method of claim 18, wherein externally measuring the location of the selected points of the fixed and at least one movable components comprises employing a plurality of cameras to obtain optical images of the components.

20. The method of claim 18, wherein the difference vector is determined in a first reference frame and wherein determining the movement commands comprises transforming the difference vector in the first reference frame into a corresponding movement vector for the patient positioner in a second reference frame.

21. The method of claim 18, further comprising the step of obtaining a radiographic image of the patient and determining the difference vector based at least partially on the patient image.

22. The method of claim 21, wherein obtaining the radiographic image comprises the steps of:

positioning at least one x-ray source and at least one x-ray imager such that the patient is interposed therebetween; and

exposing the patient and the at least one x-ray imager via the at least x-ray source.

23. The method of claim 22 comprising:

determining corresponding movement commands and movement trajectories for both the patient positioner and the at least one x-ray source and imager; and

comparing the movement trajectories with the measured locations of the selected points of the fixed and at least one movable components and between the patient positioner and the at least one x-ray source and imager so as to inhibit movement if a collision is indicated.

24. The method of claim 22, comprising positioning at least one x-ray source and at least one x-ray imager substantially along a treatment axis.

25. A system for delivering radiation therapy to a pre-selected location within a patient, the system comprising a plurality of movable components including a patient positioner and a nozzle, the system further comprising an external monitoring system that monitors the physical location of the plurality of movable components and provides signals indicative thereof and wherein the system further includes internal monitoring systems that also monitor the movement of the plurality of movable components and provides signals indicative thereof and wherein the system monitors the signals from the external and internal monitoring systems and inhibits movement of the plurality of components if the signals indicate that a collision of components is likely to occur.

26. The system of claim 25, wherein the external monitoring system images distinctive monuments of the movable components to monitor their physical location.

27. The system of claim 26, wherein the monuments comprise markers attached to selected regions of the movable components.

28. The system of claim 26, wherein the external monitoring system comprises a plurality of cameras which obtain optical images of the movable components.

29. The system of claim 25, wherein the external monitoring system also monitors for intrusion of foreign objects into a predicted travel path of the movable components and inhibits movement if a collision is indicated.

30. The system of claim 25, wherein the internal monitoring system comprise resolvers in operable communication with the moving components so as to provide information relating to the measured position of the movable components.

31. The system of claim 30, wherein the resolvers comprise rotary angle encoders.

32. The system of claim 25, further comprising a patient imager which obtains at least one image of a patient supported by the patient positioner and wherein the system evaluates the at least one patient image and provides control signals to induce at least one of the patient positioner and the nozzle to move with respect to each other to achieve a desired treatment pose.