IMAGE GUIDED RADIOSURGERY METHOD AND APPARATUS USING REGISTRATION OF 2D RADIOGRAPHIC IMAGES WITH DIGITALLY RECONSTRUCTED RADIOGRAPHS OF 3D SCAN DATA

• US 20100239153A1
• Filed: 06/03/2010
• Published: 09/23/2010
• Est. Priority Date: 08/29/2003
• Status: Active Grant

• Current Assignee: Accuray Incorporated
• Original Assignee: Accuray Incorporated
• Inventors: Kuduvalli, Gopinath, Fu, Dongshan, Qureshi, Shehrzad
• Granted Patent: US 8,280,491 B2
• Time in Patent Office: Days
• US Class Current: 382/132
• 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 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 5/107 in real time, i.e. during treatment
• CPC Class Codes: G01N 23/04 and forming images of the material
• CPC Class Codes: G06T 2207/10124 Digitally reconstructed radiograph [DRR]
• CPC Class Codes: G06T 2207/30004 Biomedical image processing
• CPC Class Codes: G06T 7/254 involving subtraction of images
• CPC Class Codes: G06T 7/32 using correlation-based methods
• CPC Class Codes: G06T 7/38 Registration of image sequences

Abstract

A set of 2D reconstructed images is generated from a pretreatment 3D scan showing an initial position of a target, wherein the set of 2D reconstructed images corresponds to perturbations from said initial position along fewer than six degrees of freedom. Said set of 2D reconstructed images are registered with one or more 2D x-ray images of said target showing a current position of the target, wherein the registering includes computing a set of 3D transformation parameters that represent a change in position of said target between said initial position of said pretreatment 3D scan and said current position of said 2D x-ray images along six degrees of freedom. A positioning system is instructed to adjust a relative position of a radiosurgical beam generator to said target by an amount prescribed by said 3D transformation parameters, wherein said target is allowed six degrees of freedom of position

Claims

1. A method comprising:

generating a set of 2D reconstructed images from a pretreatment 3D scan showing an initial position of a target, wherein the set of 2D reconstructed images corresponds to perturbations from said initial position along fewer than six degrees of freedom;

registering said set of 2D reconstructed images with one or more 2D x-ray images of said target showing a current position of the target, wherein the registering includes computing a set of 3D transformation parameters that represent a change in position of said target between said initial position of said pretreatment 3D scan and said current position of said 2D x-ray images along six degrees of freedom; and

instructing a positioning system to adjust a relative position of a radiosurgical beam generator to said target by an amount prescribed by said 3D transformation parameters, wherein said target is allowed six degrees of freedom of position.

2. The method of claim 1, wherein said set of 2D reconstructed images include a first subset of 2D reconstructed images associated with a first image plane of a first 2D x-ray image and a second subset of 2D reconstructed images associated with a second image plane of a second 2D x-ray image.

3. The method of claim 2, wherein registering said set of 2D reconstructed images with said 2D x-ray images comprises:

registering the first 2D x-ray image with the first subset of 2D reconstructed images by determining a first set of transformation parameters that represent a change in position of said target between said initial position of said pretreatment 3D scan and said current position of said first 2D x-ray image along fewer than six degrees of freedom;

registering the second 2D x-ray image with the second subset of 2D reconstructed images by determining a second set of transformation parameters that represent a change in position of said target between said initial position of said pretreatment 3D scan and said current position of said second 2D x-ray image along fewer than six degrees of freedom; and

combining the first set of transformation parameters with the second set of transformation parameters to obtain said 3D transformation parameters along six degrees of freedom.

4. The method of claim 3, wherein said first set of transformation parameters and said second set of transformation parameters each include two out-of-plane rotational parameters and three in-plane transformation parameters.

5. The method of claim 3, wherein the first set of transformation parameters represents a first five degrees of freedom, and the second set of transformation parameters represents a second five degrees of freedom, at least one of the first five degrees of freedom overlapping one of the second five degrees of freedom.

6. The method of claim 1, wherein the first set of 2D reconstructed images correspond to perturbations from said initial position along up to two degrees of freedom and the second set of 2D reconstructed images correspond to perturbations from said initial position along up to two degrees of freedom.

7. The method of claim 1, wherein the registering is performed in a plurality of search phases using combinations of search techniques and similarity measures in each search phase.

8. The method of claim 1, wherein the registering comprises:

estimating in-plane transformation parameters between the 2D x-ray images of the target and the set of 2D reconstructed images of the target in a first search phase; and

estimating out-of-plane rotation parameters between the 2D x-ray images of the target and the set of 2D reconstructed images of the target in a second search phase.

9. The method of claim 8, wherein the in-plane transformation parameters are estimated using a first similarity measure and a first search method and wherein the out-of-plane rotation parameters are estimated using a second similarity measure and a second search method.

10. The method of claim 9, further comprising:

using at least one of a third similarity measure or a third search method to iteratively refine a registration accuracy between the 2D x-ray images of the target and the set of 2D reconstructed images of the target.

11. A system comprising:

a controller having a processing device, the processing device to execute instructions for performing image registration, wherein the instructions cause the processing device to;

generate a set of 2D reconstructed images from a pretreatment 3D scan showing an initial position of a target, wherein the set of 2D reconstructed images corresponds to perturbations from said initial position along fewer than six degrees of freedom;

register said set of 2D reconstructed images with one or more 2D x-ray images of said target showing a current position of the target, wherein the registering includes computing a set of 3D transformation parameters that represent a change in position of said target between said initial position of said pretreatment 3D scan and said current position of said 2D x-ray images along six degrees of freedom; and

determine an adjustment to make to a relative position of a radiosurgical beam generator to said target based on said 3D transformation parameters, wherein said target is allowed six degrees of freedom of position.

12. The system of claim 11, wherein said set of 2D reconstructed images include a first subset of 2D reconstructed images associated with a first image plane of a first 2D x-ray image and a second subset of 2D reconstructed images associated with a second image plane of a second 2D x-ray image.

13. The system of claim 12, wherein registering said set of 2D reconstructed images with said 2D x-ray images comprises:

registering the first 2D x-ray image with the first subset of 2D reconstructed images by determining a first set of transformation parameters that represent a change in position of said target between said initial position of said pretreatment 3D scan and said current position of said first 2D x-ray image along fewer than six degrees of freedom;

registering the second 2D x-ray image with the second subset of 2D reconstructed images by determining a second set of transformation parameters that represent a change in position of said target between said initial position of said pretreatment 3D scan and said current position of said second 2D x-ray image along fewer than six degrees of freedom; and

combining the first set of transformation parameters with the second set of transformation parameters to obtain said 3D transformation parameters along six degrees of freedom.

14. The system of claim 13, wherein said first set of transformation parameters and said second set of transformation parameters each include two out-of-plane rotational parameters and three in-plane transformation parameters.

15. The system of claim 13, wherein the first set of transformation parameters represents a first five degrees of freedom, and the second set of transformation parameters represents a second five degrees of freedom, at least one of the first five degrees of freedom overlapping one of the second five degrees of freedom.

16. The system of claim 11, wherein the instructions cause the processing device to perform the registering in a plurality of search phases using combinations of search techniques and similarity measures in each search phase.

17. The system of claim 11, wherein the registering comprises:

estimating in-plane transformation parameters between the 2D x-ray images of the target and the set of 2D reconstructed images of the target in a first search phase using a first similarity measure; and

estimating out-of-plane rotation parameters between the 2D x-ray images of the target and the set of 2D reconstructed images of the target in a second search phase using a second similarity measure.

18. The system of claim 11, further comprising:

the radiosurgical beam generator, to generate a collimated radiosurgical beam; and

a positioning system, to receive commands from the controller to adjust the relative position of the radiosurgical beam generator to said target, and to adjust the relative position of the radiosurgical beam generator to said target based on the received commands.

19. The system of claim 11, further comprising:

means for generating the pretreatment 3D scan.

20. The system of claim 11, further comprising:

an imaging system, including one or more x-ray sources, to generate the one or more 2D x-ray images.