Cherenkov imaging systems and methods to monitor beam profiles and radiation dose while avoiding interference from room lighting

Patent metadata

Field	Value
Publication number	US-2016263402-A1
Application number	US-201615160576-A
Country	US
Kind code	A1
Filing date	May 20, 2016
Priority date	May 19, 2011
Publication date	Sep 15, 2016
Grant date	—

Abstract

A monitor for pulsed high energy radiation therapy using a radiation beam passing through a treatment zone, the radiation of 0.2 MEV or greater; has a camera for imaging Cherenkov light from the treatment zone; apparatus for preventing interference by room lighting, the camera synchronized to pulses of the radiation beam; and an image processor adapted to determine extent of the beam area on the patient skin from the images. Additionally an image processor determines cumulative skin dose in the treatment zone from the images. In embodiments, the processor uses a three-dimensional model of a subject to determine mapping of image intensity in images of Cherenkov light to radiation intensity in skin, applies the mapping to images of Cherenkov light to verify skin dose delivered, and accumulates skin dose by summing the maps of skin dose.

First claim

What is claimed is:

1 . A system for providing and monitoring delivery and accuracy of radiation therapy comprising:
a source of pulsed high energy radiation disposed to provide a radiation beam to a treatment zone, with high energy radiation of at least 0.2 MeV; at least one camera configured to obtain images of light emitted from the treatment zone, the camera s disposed to image the treatment zone; apparatus adapted to minimize interference by room lighting with the observations; an image processor; and apparatus adapted to record the observations; wherein the camera is synchronized to pulses of the pulsed high energy radiation.

2 . The system of claim 1 wherein the apparatus adapted to prevent interference by room lighting with the imaging system comprises apparatus adapted to synchronize pulsed room lighting to allow image capture of Cherenkov light at times without ambient lighting.

3 . The system of claim 2 , wherein the image processor is configured with machine readable code adapted to using a three-dimensional model of a subject to determine a mapping of image intensity in the images of Cherenkov light to the radiation dose deposited in skin of the subject.

4 . The system of claim 1 wherein the apparatus adapted to prevent interference by room lighting includes the image processor being adapted with machine readable instructions configured to obtain a first image of the treatment zone during at least one pulse of the high energy radiation source, and a second image of the treatment zone at a time other than during a pulse of the high energy radiation source; and with machine readable instructions configured to subtract the second image from the first image to provide an image of Cherenkov emissions from the treatment zone.

5 . The system of claim 4 , wherein the image processor is adapted with machine readable code to estimate a beam shape from the images of Cherenkov light.

6 . The system of claim 5 , wherein the image processor is adapted with machine readable code to estimate a radiation dose of the high energy radiation beam on a subject's skin from the images.

7 . The system of claim 6 , where the image processor is further adapted with machine readable code to resolve patient position relative to the treatment beam by using vascular and skin structures appearing in the emitted Cherenkov images as biological alignment features.

8 . The system of claim 7 , where the image processor is further adapted with machine readable code to compare intensity patterns from the images with images from at least one prior treatment session to determine if changes have occurred between sessions.

9 . The system of claim 8 , wherein the image processor is adapted with machine readable code to estimate cumulative skin dose across a plurality of a treatment sessions in the treatment zone.

10 . The system of claim 4 , wherein the image processor is adapted with machine readable code to estimate a radiation dose of the high energy radiation beam on a subject's skin from the images.

11 . The system of claim 4 , wherein the image processor is configured with machine readable code adapted to using a three-dimensional model of a subject to determine a mapping of image intensity in the images of Cherenkov light to the radiation dose deposited in skin of the subject.

12 . The system of claim 11 , wherein the image processor is adapted with machine readable code to estimate cumulative skin dose across a plurality of a treatment sessions in the treatment zone.

13 . The system of claim 5 , where the image processor is further adapted with machine readable code to resolve patient position relative to the treatment beam by using vascular and skin structures appearing in the emitted Cherenkov images as biological alignment features.

14 . The system of claim 5 where the image processor is further adapted with machine readable code to extract a shape of the beam, and code adapted to compare intensity patterns from the images with images from at least one prior treatment session to determine if changes have occurred and thereby to verify daily accuracy in delivery.

15 . The system of claim 4 , further comprising a positioning device configured to hold the camera in a same location, angle and position in a first fractionated radiation treatment session and all subsequent fractionated radiation treatment session.

16 . The system of claim 4 , wherein the image processor is configured to acquire multiple images of Cherenkov light during a treatment session.

17 . The system of claim 16 , wherein the image data is used to verify delivery as planned by comparison to the prescribed radiation dose.

18 . The system of claim 5 , wherein the image processor is configured with machine readable instructions to compare a skin dose determined from pre-treatment simulations to a skin dose determined from imaged Cherenkov light and to interrupt the delivery of radiation if the imaged Cherenkov signal disagrees with the pre-treatment simulations by more than a limit.

19 . The system of claim 9 , wherein the image processor is configured with machine readable instructions to compare a skin dose determined from pre-treatment simulations to a skin dose determined from imaged Cherenkov light and to interrupt the delivery of radiation if the imaged Cherenkov signal disagrees with the pre-treatment simulations by more than a limit

20 . The system of claim 4 , the image processor further configured with machine readable code to apply the mapping of image intensity from the multiple images of Cherenkov light to determine maps of skin dose, and to determine if changes in position have occurred and to warn an operator if the treatment beam design is providing excessive skin dose or excessive changes in tissue position have occurred between successive sessions of treatment.

21 . A system of claim 1 , wherein the imaging system is spectrally selective such that the imaging system is adapted to capture Cherenkov-stimulated light emissions from tissue.

22 . A method of determining surface dose during radiation treatment of a first object beneath a surface of a second object to limit dose at the surface comprising:
obtaining at least two images of the surface, and extracting a three-dimensional computer model of the surface therefrom; determining a mapping of image brightness at the surface in Cherenkov light images obtained by a digital camera to radiation intensity; recording surface brightness at the surface in a plurality of Cherenkov light images; a summing step selected from the group consisting of: using the mapping of image brightness at the surface to translate each Cherenkov light image into a surface dose image, and summing the surface dose images to provide a total session surface dose image; and summing the image brightness in each Cherenkov light image into a total session surface Cherenkov light image, and using the mapping of image brightness at the surface to translate the total session surface Cherenkov light image into a total session surface dose image; and displaying the total session surface dose image.

23 . A method of determining surface dose during radiation treatment from imaging of a fractionated radiation therapy comprising:
obtaining mulitiple images of a surface, and extracting a three-dimensional computer model of the surface therefrom; obtaining Cherenkov light images synchronized to beam pulses, the Cherenkov light images obtain

Assignees

• Dartmouth College

Inventors

• Zhang Rongxiao
• Pogue Brian William
• Glaser Adam K
• Gladstone David J
• Jarvis Lesley A
• Andreozzi Jacqueline M
• Jiang Shudong
• Davis Scott Christian
• Axelsson Johan Jakob

Classifications

• A61N5/1065

  Beam adjustment · CPC title

• A61N5/1077

  Beam delivery systems · CPC title

• A61N5/1071 Primary

  for verifying the dose delivered by the treatment plan · CPC title

• A61N2005/1059

  using cameras imaging the patient · CPC title

• A61N5/1049

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