Patient alignment system with external measurement and object coordination for radiation therapy system

• US 20060017022A1
• Filed: 08/12/2004
• Published: 01/26/2006
• 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., Baumann, Michael A., Lesyna, David A., Cheng, Chieh C., Anderson, Daniel C., Rigney, Nickolas S., Miller, Daniel W.
• Granted Patent: US 7,199,382 B2
• Time in Patent Office: Days
• US Class Current: 250/497.100
• 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 alignment system for a radiation therapy system. The alignment system includes multiple external measurement devices which obtain position measurements of components of the radiation therapy system which are movable and/or are subject to flex or other positional variations. The alignment system employs the external measurements to provide corrective positioning feedback to more precisely register the patient and align them with a radiation beam. The alignment system can be provided as an integral part of a radiation therapy system or can be added as an upgrade to existing radiation therapy systems.

Claims

1. A radiation therapy delivery system comprising:

a gantry;

a patient fixation device configured to secure a patient with respect to the patient fixation device;

a patient positioner interconnected to the patient fixation device so as to position the patient fixation device along 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 fixation device and the nozzle; and

a controller which receives the position measurements of at least the patient fixation device and the nozzle and provides control signals to the patient positioner to position the patient in a desired orientation with respect to the beam axis.

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

3. The system of claim 1, further comprising a plurality of markers fixed to at least the patient fixation device and the 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, wherein the system further comprises a patient imaging system which obtains an image of the patient and 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 provides control signals to move the patient positioner and the patient target isocenter into a desired patient pose with respect to the nozzle.

7. The system of claim 5, wherein the patient imaging system comprises at least one radiographic imager.

8. The system of claim 7, wherein the patient imaging system comprises at least one x-ray source and at least one solid state x-ray imager.

9. The system of claim 5, wherein the patient imaging system is movable in and out of the beam axis.

10. The system of claim 5, wherein the patient imaging system obtains images of the patient from multiple perspectives for more precise determination of the target isocenter.

11. The system of claim 1, wherein obtaining position measurements and providing the positioning control signals to the patient positioner is performed iteratively.

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

13. The system of claim 12, wherein the system determines an orientation and position difference vector measured in a first frame of reference by the external measurement devices and transforms the difference vector into at least one correction vector in a second frame of reference to position the patient in the desired pose with respect to the beam axis.

14. The system of claim 13, wherein the at least one correction vector induces the nozzle to revolve about the gantry isocenter.

15. A patient positioning system for a radiation therapy system having a plurality of components that are subject to movement, the positioning system comprising:

a plurality of external measurement devices arranged to obtain position measurements of the plurality of 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 information from the plurality of external measurement devices and providing movement commands to the movable patient support to align the patient in a desired pose such that the positioning system compensates for movement of the plurality of components.

16. The positioning system of claim 15, 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.

17. The positioning system of claim 16, further comprising a patient imager system which obtains an image of the patient and a target iso-center, wherein the positioning system determines the position of the target iso-center and aligns the target iso-center with the beam delivery aiming point.

18. The positioning system of claim 15, wherein at least one of the components subject to movement is actively controllable and wherein the positioning system provides a feedback function to align the patient in the desired pose by providing control signals to position the at least one actively controllable component.

19. The positioning system of claim 15, 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.

20. The positioning system of claim 19, 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.

21. A method of registering and positioning a patient for delivery of therapy with a system having a plurality of components subject to movement, 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 plurality of components;

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

providing movement commands to the patient positioner to bring the patient to the desired patient pose.

22. The method of claim 21, wherein externally measuring the location of the selected points of the plurality of components comprises employing a plurality of cameras to obtain optical images of the plurality of components.

23. The method of claim 21, wherein the difference vector is determined in a first reference frame and wherein providing 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.

24. The method of claim 21, 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.

25. The method of claim 24, wherein obtaining the radiographic image comprises the steps of:

positioning an x-ray source and an x-ray imager generally along a therapy beam axis with the patient interposed therebetween;

exposing the patient and the x-ray imager via the x-ray source; and

removing the x-ray source and imager from the therapy beam axis.

26. A positioning system for use with a radiation treatment facility wherein the radiation treatment facility has a plurality of components that includes a source of particles and a nozzle from which the particles are emitted, wherein the nozzle is movable with respect to the patient to facilitate delivery of the particles to a selected region of the patient via a plurality of different paths, the positioning system comprising:

a patient positioner that receives the patient wherein the patient positioner is movable so as to orient the patient with respect to the nozzle to facilitate delivery of the particles in the selected region of the patient;

a monitoring system that images at least one component of the radiation treatment facility in proximity to the patient positioner, wherein the monitoring system develops a treatment image indicative of the orientation of the at least one component with respect to the patient prior to treatment; and

a control system that controls delivery of particles to the patient wherein the control system receives signals indicative of the treatment to be performed, the signals including a desired orientation of the at least one component when the particles are to be delivered to the patient, wherein the control system further receives the treatment image and the control system evaluates the treatment image to determine an actual orientation of the at least one component prior to treatment and wherein the control system compares the actual orientation of the at least one component prior to treatment to the desired orientation of the at least one component and, if the actual orientation does not meet a pre-determined criteria for correspondence with the desired orientation, the control system sends signals to the patient positioner to move the patient positioner such that the actual orientation more closely corresponds to the desired orientation during delivery of the particles.

27. The system of claim 26, wherein the patient positioner comprises:

a patient fixation device for maintaining the portion of the patient to be treated in a substantially immobile orientation with respect to the patient fixation device; and

a movement mechanism coupled to the patient fixation device for moving the patient fixation device in response to signals from the control system to thereby move the patient into an actual orientation that more closely corresponds to the desired orientation during delivery of particles.

28. The system of claim 27, wherein the patient fixation device comprises a patient pod in which the patient is positioned so as to be retained in a substantially immobile orientation with respect to the patient pod.

29. The system of claim 28, wherein the movement mechanism comprises a robot assembly attached to the patient pod that allows for translational and rotational movement of the patient pod about three orthogonal axes.

30. The system of claim 26, wherein the monitoring system comprises at least one imaging device that visually images the at least one component of the radiation treatment facility to determine the actual orientation of the at least one component.

31. The system of claim 30, wherein the at least one imaging device comprises a plurality of cameras that capture visual images of the at least one component of the radiation treatment facility wherein the plurality of cameras are located so as to be able to determine the actual orientation of the at least one component with respect to three orthogonal planes.

32. The system of claim 31, wherein the plurality of cameras capture visual images of the at least one component such that a three dimensional location of a monument associated with the at least one component can be resolved to determine the actual orientation of the at least one component.

33. The system of claim 32, further comprising at least one external marker attached to the at least one component wherein the at least one external marker comprises the monument associated with the at least one component.

34. The system of claim 26, wherein the monitoring system images a plurality of components, including the nozzle, and the control system adjusts the patient positioner such that the plurality of components are within the pre-selected criteria of the desired orientation.

35. The system of claim 26, wherein the control system defines a set point of reference within a field of view of the monitoring system and determines the actual orientation and the desired orientation with respect to the set point of reference.

36. The system of claim 35, wherein the monitoring system further images the patient positioner and the control system receives signals indicative of the orientation of the patient positioner and uses these signals to determined the actual and desired orientation of the at least one component.

37. The system of claim 26, wherein the control system is adapted to receive signals from the radiation treatment facility indicative of the movement of the components within the system and wherein the control system utilizes these signals to determine the actual and desired orientation of the at least one component.