Calibration of a stereoscopic camera system for use with a radio therapy treatment apparatus

Patent metadata

Field	Value
Publication number	US-2024042241-A1
Application number	US-202318487148-A
Country	US
Kind code	A1
Filing date	Oct 16, 2023
Priority date	Jul 17, 2013
Publication date	Feb 8, 2024
Grant date	—

Abstract

The disclosed calibration method includes a calibration phantom positioned on an adjustable table on the surface of a mechanical couch, with the phantom's centre at an estimated location for the iso-centre of a radio therapy treatment apparatus. The calibration phantom is then irradiated using the apparatus, and the relative location of the center of the calibration phantom and the iso-centre of the apparatus is determined by analyzing images of the irradiation of the calibration phantom. The calibration phantom is then repositioned by the mechanical couch applying an offset corresponding to the determined relative location of the centre of the calibration phantom and the iso-centre of the apparatus to the calibration phantom. Images of the relocated calibration phantom are obtained, to which the offset has been applied, and the obtained images are processed to set the co-ordinate system of a stereoscopic camera system relative to the iso-centre of the apparatus.

First claim

1 . A radiotherapy system comprising:
a radiotherapy treatment apparatus; a detector positioned to receive radiation from the radiotherapy treatment apparatus and to provide irradiation data representative of the received radiation; at least one processor configured to process the irradiation data representative of the received radiation to determine at least one of a position or orientation of a phantom positioned relative to the radiotherapy treatment apparatus, wherein the phantom contains one or more regions of material that provide a differentiated contrast to other regions of the phantom in the irradiation data representative of the received radiation, and wherein the at least one processor is configured to determine at least one of a position or orientation of the phantom based at least in part on the differentiated contrast; a stereoscopic camera system configured to image an exterior surface of an object positioned relative to the radiotherapy treatment apparatus system, and to provide image data representative of the exterior surface of the subject; and at least one processor configured to use the at least one of the position or orientation of the phantom to calibrate the stereoscopic camera system relative to the radiotherapy treatment apparatus.

2 . The system according to claim 1 , wherein a single processor is configured to both process the irradiation data representative of the received radiation to determine at least one of a position or orientation of a phantom positioned relative to the radiotherapy treatment apparatus, and also use the at least one of the position or orientation of the phantom to calibrate the stereoscopic camera system relative to the radiotherapy treatment apparatus.

3 . The system according to claim 1 , wherein at least one processor is configured to also use image data representative of the exterior surface of the phantom provided by the stereoscopic camera system to calibrate the stereoscopic camera system relative to the radiotherapy treatment apparatus.

4 . The system according to claim 3 , wherein calibrating the stereoscopic camera system relative to the radiotherapy treatment apparatus comprises determining a difference between a coordinate system of the stereoscopic camera system and a coordinate system of the radiotherapy treatment apparatus.

5 . The system according to claim 3 , wherein at least one processor is configured to process image data representative of the exterior surface of the phantom to determine a difference between the image data representative of the exterior surface of the phantom and the at least one of the position or orientation of the phantom.

6 . The system according to claim 1 , further comprising:
a movable couch having axes of motion for positioning a subject relative to the coordinate system of the radiotherapy treatment system, wherein, during calibration, the movable couch positions the phantom relative to the coordinate system of the radiotherapy treatment system.

7 . The system according to claim 1 , wherein
the radiotherapy treatment apparatus irradiates the phantom at plural angles, and at least one processor is configured to process irradiation data representative of the received radiation to determine at least one of a position or orientation of a phantom positioned relative to the radiotherapy treatment apparatus.

8 . The system according to claim 1 , wherein at least one processor is configured to process image data representative of the exterior surface of the phantom to calibrate the coordinate system of the stereoscopic camera system relative to the radiotherapy treatment apparatus while the phantom is positioned at an estimated location of the iso-center of the radiotherapy treatment apparatus.

9 . The system according to claim 8 , wherein at least one processor is configured to process image data representative of the exterior surface of the phantom to determine a difference between at least one of the position or orientation of the phantom and stored reference data.

10 . The system according to claim 9 , wherein the stored reference data is reference data of the phantom.

11 . The system according to claim 9 , wherein the stored reference data is reference data of the physical calibration phantom having a known position relative to the iso-center of said radiotherapy treatment apparatus.

12 . The system according to claim 3 , wherein calibrating the stereoscopic camera system relative to the radiotherapy treatment apparatus comprises determining a difference between the at least one of the position or orientation of the phantom and stored reference data.

12 . The system according to claim 11 , wherein the stored reference data is generated from scan images of the phantom.

14 . The system according to claim 12 , wherein the phantom comprises a calibration cube and the stored reference data contains a model of a reference surface of the calibration cube.

15 . The system according to claim 1 , wherein the one or more regions of material that provide a differentiated contrast to other regions of the phantom in the irradiation data comprise one or more markers.

16 . The system according to claim 1 , wherein the one or more regions of material that provide a differentiated contrast to other regions of the phantom in the irradiation data are arranged asymmetrically within the physical calibration phantom.

17 . The system according to claim 1 , wherein said physical calibration phantom is configured with a known asymmetrical arrangement of regions of material that provide a differentiated contrast to other regions of the phantom in the irradiation data provided in a fixed orientation within the body of the physical calibration phantom, so as to enable the position and orientation of said physical calibration phantom to be determined from the image of the irradiated physical calibration phantom, enabling the position and orientation of the physical calibration phantom to be determined with respect to the coordinate system of the radiotherapy treatment system.

18 . A radiotherapy system comprising:
a radiotherapy treatment apparatus configured to irradiate a subject positioned relative to a coordinate system of the radiotherapy treatment apparatus; a stereoscopic camera assembly configured to image the subject, the stereoscopic camera assembly having a camera coordinate system; and at least one processor configured to process image data obtained by the stereoscopic camera assembly to determine a location of the subject positioned relative to the coordinate system of the radiotherapy treatment apparatus, wherein the at least one processor is configured to calibrate the camera coordinate system by:
receiving image data from the stereoscopic camera assembly of a physical calibration phantom positioned relative to the camera coordinate system;
receiving image data from the radiotherapy apparatus of the irradiated physical calibration phantom; and
using the received image data from the stereoscopic camera assembly of the physical calibration phantom and the received image data from the radiotherapy apparatus of the irradiated physical calibration phantom to determine a difference between the camera coordinate system and the coordinate system of the radiotherapy treatment apparatus.

19 . The system according to claim 18 , wherein calibrating the camera coordinate system comprises comparing the received image data from the stereoscopic camera assembly of the physical calibration phantom to reference data.

20 . The

Assignees

• Vision Rt Ltd

Inventors

• Meir Ivan
• Allen Martin
• Hale Gideon
• Smith Norman
• Howe Robert

Classifications

• A61N5/1075 Primary

  for testing, calibrating, or quality assurance of the radiation treatment apparatus · CPC title

• A61N5/1049 Primary

  for verifying the position of the patient with respect to the radiation beam · CPC title

• A61B6/584

  determining position of components of the apparatus or device using images of the phantom · CPC title

• G06T7/85

  Stereo camera calibration · CPC title

• G06T7/0012

  Biomedical image inspection · CPC title