Method and system for using Cherenkov radiation to monitor beam profiles and radiation therapy

• US 10,201,718 B2
• Filed: 05/18/2012
• Issued: 02/12/2019
• Est. Priority Date: 05/19/2011
• Status: Active Grant

• Current Assignee: The Trustees of Dartmounth College (Dartmouth College)
• Original Assignee: The Trustees of Dartmounth College (Dartmouth College)
• Inventors: Pogue, Brian William, Gladstone, David Joseph, Davis, Scott Christian, Axelsoon, Johan Jakob, Glaser, Adam Kenneth, Zhang, Rongxiao
• Primary Examiner(s): Park, Patricia J
• Application Number:
  US14/118,825
• Publication Number:
  US 20140114150A1
• Time in Patent Office: 2,461 Days
• Field of Search: None
• CPC Class Codes: A61B 5/0071 by measuring fluorescence emission
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61N 2005/1076 using a dummy object placed in the radiation field, e.g. phantom
• CPC Class Codes: A61N 5/1065 Beam adjustment
• CPC Class Codes: A61N 5/1075 for testing, calibrating, or quality assurance of the radiation treatment apparatus
• CPC Class Codes: G01T 1/22 with Cerenkov detectors

Abstract

A system for providing monitored radiation therapy has a high energy radiation source, apparatus for excluding uncontrolled ambient light, and apparatus for collecting light emitted from a subject. The system has apparatus for spectrally analyzing the collected light, and a processor for determining oxygenation or other metabolic function of tissue within the subject from spectral analysis of the collected light. The system monitors radiation therapy by providing a beam of high energy radiation; collecting Cherenkov and/or photoluminescent light from the subject, the light generated along the beam; spectrally analyzing the light; and determining oxygenation or metabolic function of tissue from the spectral analysis. Beam profile of the system is calibrated by imaging from multiple angles Cherenkov and/or photoluminescent light emitted by a phantom placed in the beam in lieu of a subject, captured images are analyzed to determine beam profile.

Claims

1. A system for providing and monitoring radiation therapy comprising:

a radiation treatment machine adapted to provide high energy radiation and disposed to provide a pulsed radiation beam having a direction and shape configured to provide radiation treatment to a subject in a treatment zone, the radiation treatment machine external to the treatment zone;

a camera adapted to image the subject in combined ambient light and Cherenkov light generated by interaction of the radiation beam with the subject and emitted from the subject in the treatment zone to form a Cherenkov image;

a processor;

timing interfaces adapted to synchronize imaging of light emitted from the subject to during pulses of the high energy radiation emitted by the radiation treatment machine; and

firmware in the processor adapted to subtract a background image from the Cherenkov image, the background image being an image of the subject in ambient room lighting captured by the camera between pulses of the high energy radiation.

2. The system of claim 1 wherein the timing interfaces configure the camera to detect light during at least one beam pulse as the Cherenkov image, and light immediately following the at least one beam pulse as a fluorescent image.

3. The system of claim 2 wherein the camera is adapted to perform spectral analysis of light, and where the processor is adapted to determine a metabolic activity of tissue within the subject from spectral analysis of light collected from the subject.

4. The system of claim 3 wherein the fluorescent light is emitted from fluorophores induced in the tissue by prior administration of a biochemical compound to the subject, the biochemical compound being a compound that localizes in tumor tissues of the subject.

5. The system of claim 2 wherein the fluorescent light is emitted from fluorophores induced in the tissue by prior administration of a biochemical compound to the subject, the biochemical compound being a compound that localizes in tumor tissues of the subject.

6. The system of claim 1 wherein the camera is adapted to perform spectral analysis of light, and where the processor is adapted to determine a metabolic activity of tissue within the subject from spectral analysis of light collected from the subject.

7. The system of claim 1 wherein the processor is adapted to determine a metabolic activity of tissue from fluorescent light emitted within the subject, the fluorescent light emitted upon stimulation by the Cherenkov radiation.

8. The system of claim 7 wherein the fluorescent light is emitted from fluorophores induced in the tissue by prior administration of a biochemical compound to the subject, the biochemical compound being a compound that localizes in tumor tissues of the subject.

9. The system of claim 7 wherein the timing interfaces configure the camera to detect light during at least one beam pulse as the Cherenkov image, and light immediately following the at least one beam pulse as a fluorescent image.

10. The system of claim 8 wherein the camera is adapted to spectrally analyze the collected light.

18. The system of claim 1 wherein the system is configured to integrate light over a plurality of pulses of the beam for each Cherenkov image.

19. The system of claim 1 wherein the processor is configured to sum or average Cherenkov light acquired over a plurality of pulses of the beam prior to subtracting the background image from the Cherenkov image.

11. A system for monitoring radiation therapy machines of the type adapted to provide pulsed high energy radiation having a direction and shape configured to provide radiation treatment to a subject in a treatment zone, the radiation treatment machine external to the treatment zone, comprising:

at least one camera adapted to image the subject in ambient and Cherenkov light generated by interaction of the radiation beam with a phantom or subject in the treatment zone and emitted from the phantom in the treatment zone to form a Cherenkov image contaminated by ambient light;

a processor; and

timing interfaces adapted to synchronize imaging of light emitted from the phantom or subject to during the pulses of the high energy radiation emitted by the radiation treatment machine, and firmware in the processor adapted to subtract a background image from the Cherenkov image, wherein the background image is captured by the camera in ambient room lighting between pulses of the high energy radiation.

12. The system of claim 11 wherein the system further comprises:

a tissue phantom containing a transparent or translucent material positioned in the treatment zone;

wherein the at least one camera is adapted to image the phantom in the treatment zone from a plurality of angles, allowing a plurality of views of an emissions zone in the phantom; and

an image processing system comprising apparatus for receiving images from the at least one camera, at least one processor, and a memory comprising machine readable instructions for processing the images from the one or more cameras to construct a tomographic three-dimensional model of the emissions zone.

20. The system of claim 11 wherein the processor is configured to sum or average Cherenkov light acquired over a plurality of pulses of the beam prior to subtracting the background image from the Cherenkov image.

13. A method of monitoring radiation therapy of a subject comprising:

using a radiation treatment machine to provide a beam of pulses of high energy radiation for radiation therapy;

imaging light emitted from the subject to form a Cherenkov image, the light being Cherenkov radiation generated within an emissions zone along the beam in the treatment zone as the beam intersects tissue of the subject, the imaging light emitted from the subject to form a Cherenkov image being synchronized to and performed during the pulses of high energy radiation;

obtaining a background image of the subject in ambient light, the obtaining a background image of the subject in ambient light being performed between the pulses of high energy radiation;

correcting the Cherenkov image by subtracting the background image;

determining a three dimensional model of the emissions zone within the subject.

14. The method of claim 13 further comprising determining a metabolic activity of tissue within the subject from the spectral analysis of fluorescent light collected from the subject, the fluorescent light emitted in consequence of absorption of Cherenkov radiation within the subject.

15. The method of claim 14 wherein the metabolic activity of tissue is determined from fluorescent light emitted by protoporphyrin IX within the tissue.

16. The method of claim 15 further comprising administering 5 aminolevulinic acid (5-ALA) to the subject, and wherein at least some of the protoporphyrin IX within the tissue is generated by metabolism of 5-ALA.

17. The method of claim 14 further comprising using a timing interface to pulse room lighting on when the beam is off, and for synchronizing the collecting of light to pulses of the beam.