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

Patent metadata

Field	Value
Publication number	US-12042671-B2
Application number	US-202318542832-A
Country	US
Kind code	B2
Filing date	Dec 18, 2023
Priority date	Jul 17, 2013
Publication date	Jul 23, 2024
Grant date	Jul 23, 2024

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

The invention claimed is:

1. 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.

2. The system according to claim 1 , 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.

3. The system according to claim 1 , wherein calibrating the camera coordinate system comprises comparing the received image data from the radiotherapy apparatus of the physical calibration phantom to reference data.

4. The system according to claim 1 , wherein one or more differences between the coordinate system of the stereoscopic camera assembly and the coordinate system of the radiotherapy treatment apparatus is or are used to calculate a transformation between the coordinate system of the stereoscopic camera assembly and the coordinate system of the radiotherapy treatment apparatus.

5. The system according to claim 4 , wherein transformation aligns the coordinate system of the stereoscopic camera assembly with the coordinate system of the radiotherapy treatment apparatus.

6. A calibration system for use with a radiotherapy treatment system having a coordinate system, said calibration system comprising:
a stereoscopic camera assembly configured to image a subject positioned relative to a coordinate system of the radiotherapy treatment system, the stereoscopic camera assembly having a camera coordinate system; and
at least one processor configured to calibrate the camera coordinate system relative to the coordinate system of the radiotherapy treatment apparatus, wherein during a calibration:
the stereoscopic camera assembly images a physical calibration phantom positioned relative to the coordinate system of the radiotherapy treatment system;
the at least one processor receives image data of the physical calibration phantom from the stereoscopic camera assembly;
the at least one processor receives radiation image data of the physical calibration phantom irradiated by the radiotherapy treatment system; and
the at least one processor, based at least in part on the received image data of the physical calibration phantom from the stereoscopic camera assembly and the received radiation image data of the irradiated physical calibration phantom, determines a difference between the camera coordinate system and the coordinate system of the radiotherapy treatment apparatus.

7. The system according to claim 6 , wherein during a calibration, the at least one processor evaluates the received image data of the physical calibration phantom from the stereoscopic camera assembly with respect to reference data.

8. The system according to claim 7 , wherein the at least one processor determines a difference between the camera coordinate system and the coordinate system of the radiotherapy treatment apparatus based at least in part on the evaluation of the received image data of the physical calibration phantom from the stereoscopic camera assembly with respect to reference data.

9. Non-transitory computer readable storage media having data stored therein representing software executable by at least one computer processor for calibrating one or more aspects of a radiotherapy system, the software including instructions stored thereon that when executed on the at least one computer processor, cause the processor to:
receive radiation data of a phantom positioned in a radiotherapy treatment apparatus;
process the radiation data of the phantom to determine at least one of a position or orientation of the phantom, wherein the phantom contains one or more regions of material that provide a differentiated contrast to other regions of the phantom in the irradiation image data representative of the received radiation, and wherein the determination of at least one of a position or orientation of the phantom is based at least in part on the differentiated contrast;
receive image data of an exterior surface of the phantom; and
generate calibration data from information that includes the at least one of the position or orientation of the phantom and the image data of an exterior surface of the phantom.

10. The non-transitory computer readable storage media according to claim 9 , wherein the calibration data is generated from information further including reference data.

11. The non-transitory computer readable storage media according to claim 10 , wherein the reference data is reference data of the physical calibration phantom.

12. The non-transitory computer readable storage media according to claim 9 , wherein the calibration data includes a difference between a coordinate system of a stereoscopic camera assembly used to generate the image data of an exterior surface of the phantom and a coordinate system of a radiation apparatus used to generate the radiation data of a phantom.

13. The non-transitory computer readable storage media according to claim 12 , further comprising:
using one or more differences between the coordinate system of the stereoscopic camera assembly and the coordinate system of the radiation apparatus to calculate a transformation between the coordinate system of the stereoscopic camera assembly and the coordinate system of the radiation apparatus, and wherein the transformation aligns the coordinate system of the stereoscopic camera assembly with the coordinate system of the radiation apparatus.

Assignees

• Vision Rt Ltd

Inventors

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

Classifications

• G06T2207/30004

  Biomedical image processing · CPC title

• G06T7/0012

  Biomedical image inspection · CPC title

• A61N2005/1059

  using cameras imaging the patient · CPC title

• G06T7/85

  Stereo camera calibration · CPC title

• A61B6/584

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