Automatic correlation modeling of an internal target

• US 20090110238A1
• Filed: 10/26/2007
• Published: 04/30/2009
• Est. Priority Date: 10/26/2007
• Status: Active Grant

• Current Assignee: Accuray Incorporated
• Original Assignee: Accuray Incorporated
• Inventors: Sayeh, Sohail, Sheng, Ye, Li, Shutian
• Granted Patent: US 9,248,312 B2
• Time in Patent Office: Days
• US Class Current: 382/103
• CPC Class Codes: A61B 2034/105 Modelling of the patient, e.g. for ligaments or bones
• CPC Class Codes: A61B 2034/107 Visualisation of planned trajectories or target regions
• CPC Class Codes: A61B 2090/3945 Active visible markers, e.g. light emitting diodes
• CPC Class Codes: A61B 2090/3966 Radiopaque markers visible in an X-ray image
• CPC Class Codes: A61B 2560/0475 Special features of memory means, e.g. removable memory cards
• CPC Class Codes: A61B 5/1127 using markers
• CPC Class Codes: A61B 5/113 occurring during breathing
• CPC Class Codes: A61B 5/1135 by monitoring thoracic expansion
• CPC Class Codes: A61B 5/7246 using correlation, e.g. template matching or determination of similarity
• CPC Class Codes: A61B 5/7285 for synchronising or triggering a physiological measurement or image acquisition with a physiological event or waveform, e.g. an ECG signal A61B6/5205, A61B6/541, A61B8/5207, A61B8/543 take precedence
• CPC Class Codes: A61B 5/7292 Prospective gating, i.e. predicting the occurrence of a physiological event for use as a synchronisation signal
• CPC Class Codes: A61B 6/541 involving acquisition triggered by a physiological signal
• CPC Class Codes: A61N 2005/1051 using an active marker markers in general A61B90/39
• CPC Class Codes: A61N 2005/1061 using an x-ray imaging system having a separate imaging source
• CPC Class Codes: A61N 2005/1074 Details of the control system, e.g. user interfaces
• CPC Class Codes: A61N 5/103 Treatment planning systems
• CPC Class Codes: A61N 5/1037 taking into account the movement of the target, e.g. 4D-image based planning
• CPC Class Codes: A61N 5/1049 for verifying the position of the patient with respect to the radiation beam
• CPC Class Codes: A61N 5/107 in real time, i.e. during treatment
• CPC Class Codes: A61N 5/1077 Beam delivery systems

Abstract

A method and apparatus to automatically control the timing of an image acquisition by an imaging system in developing a correlation model of movement of a target within a patient.

Claims

1. A method, comprising:

automatically triggering image acquisition of a plurality of pretreatment images of a target, each of the plurality of pretreatment images acquired at a specified time; and

generating a correlation model that maps movement of an external marker to a target location of the target using the plurality of pretreatment images.

2. The method of claim 1, wherein said automatically triggering each of the plurality of pretreatment images comprises:

selecting a desired phase of a periodic cycle in which to acquire an image;

automatically determining whether the target is in the desired phase of the periodic cycle; and

sending a command to an imaging system to acquire a pretreatment image when the target is in the desired phase of the periodic cycle.

3. The method of claim 2, wherein said selecting is performed by a user.

4. The method of claim 1, wherein said automatically triggering comprises automatically triggering image acquisition at substantially evenly-distributed points of a periodic cycle, and wherein said automatically triggering each of the plurality of pretreatment images comprises:

obtaining historical data of movement of the target in one or more previous periodic cycles;

dividing the historical data into a plurality of regions based on magnitude of movement of the target;

distinguishing between inspiration and expiration movement of the historical data;

establishing a plurality of model metric regions using the plurality of regions and the distinguished inspiration and expiration movement, wherein the plurality of model metric regions correspond to a plurality of phases of the periodic cycle;

determining whether a current sample of the target movement is in a desired phase of the periodic cycle by categorizing the current sample into one of the plurality of model metric regions; and

sending an imaging command to an imaging system to acquire the pretreatment image when the current sample is in the desired phase of the periodic cycle.

5. The method of claim 4, wherein said obtaining comprises acquiring a plurality of data points representative of a corresponding plurality of positions over time of an external marker associated with a patient, wherein the plurality of positions of the external marker define an external path of movement of the external marker, and the external path of movement defines the periodic cycle of the patient.

6. The method of claim 5, wherein said generating the correlation model comprises:

identifying a path of movement of the target based on the plurality of data points and the plurality of pretreatment images at the substantially evenly-distributed points of the periodic cycle; and

developing the correlation model using the path of movement of the target.

7. The method of claim 1, further comprising:

deriving a target position of the target based on the correlation model.

sending a position signal associated with the target position to a beam generator controller; and

controlling the beam generator controller to direct a beam at the target.

8. The method of claim 5, further comprising updating the correlation model in response to an acquisition of a new data point.

9. The method of claim 1, further comprising:

periodically generating positional data about the target by automatically acquiring additional images of the target during treatment; and

continuously generating positional data about external motion of the external marker during treatment.

10. An apparatus, comprising:

a data storage device to store a plurality of displacement points of an external marker indicative of the motion of the external marker during a periodic cycle; and

a processing device coupled to the data storage device, the processing device to determine a specified time in the periodic cycle, which corresponds to a first phase of the periodic cycle, in which to acquire an image of a target based on the plurality of displacement points, and to transmit a signal to automatically trigger an imaging system to acquire the image of the target at the first phase of the periodic cycle.

11. The apparatus of claim 10, wherein the processing device is configured to select the first phase of the periodic cycle, to automatically determine whether the target is in the first phase of the periodic cycle, and to send the signal to automatically trigger the imaging system to acquire the image of the target when the target is in the first phase of the periodic cycle.

12. The apparatus of claim 10, wherein the processing device is configured to allow a user to select the first phase of the periodic cycle, to automatically determine whether the target is in the first phase of the periodic cycle, and to send the signal to automatically trigger the imaging system to acquire the image of the target when the target is in the first phase of the periodic cycle.

13. The apparatus of claim 10, further comprising the imaging system coupled to the processing device, wherein the imaging system is configured to receive the signal from the processing device, and to acquire the image of the target when the imaging system receives the signal.

14. The apparatus of claim 10, wherein the processing device is configured to determine a second specified time in the periodic cycle at which to acquire a second image of the target that corresponds to a second phase of the periodic cycle, and to trigger the imaging system to acquire the second image of the target at the second phase of the periodic cycle.

15. The apparatus of claim 14, wherein the data storage device is configured to store the image of the target and the second image of the target.

16. The apparatus of claim 14, wherein the processing device is configured to generate a correlation model based on the image, the second image, and the plurality of displacement points.

17. The apparatus of claim 16, wherein the processing device is configured to identify a path of movement of the target to generate the correlation model.

18. The apparatus of claim 10, wherein the processing device comprises:

a first interface to send a command to the imaging system to automatically trigger the imaging system to acquire the image of the target at the specified time during the periodic cycle;

a second interface to receive the plurality of displacement points of the external marker measured by a motion tracking system.

19. An apparatus, comprising:

means for receiving a plurality of data points representative of a corresponding plurality of positions over time of an external marker associated with a patient, wherein the plurality of positions of the external marker defines an external path of movement of the external marker, the external path of movement defining a periodic cycle of the patient; and

means for automatically triggering an imaging system to acquire an image of a target within the patient at a specific time in the periodic cycle based on the plurality of data points.

20. The apparatus of claim 19, further comprising:

means for generating evenly-distributed model points during the periodic cycle using the plurality of data points; and

means for generating a correlation model using the evenly-distributed model points.

21. The apparatus of claim 20, wherein the means for automatically triggering reduces a number of images acquired to generate the correlation model.

22. The apparatus of claim 20, wherein the means for automatically triggering reduces an amount of time to generate the correlation model.

23. A system, comprising:

a motion tracking system to track motion of an external marker associated with a patient, the motion of the external marker is indicative of a periodic cycle of the patient;

an imaging system to acquire an image of a target within the patient; and

a target locating system coupled to the motion tracking system and the imaging system, the target locating system to automatically trigger the imaging system to trigger the acquisition of the image at a specified time.

24. The system of claim 23, wherein the target locating system is configured to determine the periodic cycle based on the motion of the external marker, to automatically select a phase of the periodic cycle, to determine when the target is in the selected phase of the periodic cycle, and to automatically trigger image acquisition by the imaging system when the target is in the selected phase of the periodic cycle.

25. The system of claim 23, wherein the target locating system is configured to determine the periodic cycle based on the motion of the external marker, to allow a user to select a phase of the periodic cycle, to determine when the target is in the selected phase of the periodic cycle, and to automatically trigger image acquisition by the imaging system when the target is in the selected phase of the periodic cycle.