X-ray CT-or MRI-based quantitative correction of Cherenkov light emission in radiation dose imaging

Patent metadata

Field	Value
Publication number	US-12029922-B2
Application number	US-202017627633-A
Country	US
Kind code	B2
Filing date	Jul 15, 2020
Priority date	Jul 15, 2019
Publication date	Jul 9, 2024
Grant date	Jul 9, 2024

Abstract

A system for monitoring radiation treatment images Cherenkov emissions from tissue of a subject. A processor of the system determines densities of a surface layer of the subject from 3D images of the tissue to determine correction factors. The processor uses these factors to correct the Cherenkov images for attenuation of Cherenkov light by tissue, making them proportional to radiation dose. In embodiments, the system obtains reflectance images of the subject, determines second correction factors therefrom, and applies the second correction factors to the Cherenkov emissions images. In embodiments, the corrected images of Cherenkov emissions are compared to dose maps of a treatment plan. A method of correcting Cherenkov emissions images includes determining tissue characteristics from CT or MRI images in a surface volume where Cherenkov is expected, using; imaging Cherenkov emissions; and using the tissue characteristics to correct the images for variations in Cherenkov light propagation through the tissue.

First claim

What is claimed is:

1. A system for monitoring a radiation treatment of a subject by generating and correcting images of Cherenkov emissions from a tissue of the subject comprising:
a camera adapted to create images of Cherenkov emissions from the tissue of the subject, the Cherenkov emissions produced during the radiation treatment of the subject by an interaction of a treatment beam with the tissue of the subject;
a source of three-dimensional voxel-based images of the tissue of the subject, selected from the group consisting of X-ray Computed Tomography (CT) images and Magnetic Resonance Imaging (MRI) images;
a processor adapted by a firmware in a memory to determine properties of a surface layer of the tissue of the subject from the three-dimensional voxel-based images of the tissue of the subject and determine optical Cherenkov correction factors (CF) compensating for a tissue attenuation therefrom using a correction factor determination method selected from the group consisting of:
calculating the optical Cherenkov correction factors based upon an electron density in the surface layer of the tissue of the subject as provided by the X-ray CT images,
estimating a property map of surface layers of the tissue of the subject from the MRI images and calculating the optical Cherenkov correction factors therefrom,
determining a tissue type map of the surface layers of the tissue of the subject, the tissue type map derived from the three-dimensional voxel-based images of the tissue of the subject, and
determining the optical Cherenkov correction factors for a Cherenkov attenuation by a tissue type therefrom;

the processor configured to apply the optical Cherenkov correction factors (CF) to the images of Cherenkov emissions from the tissue of the subject to prepare Cherenkov images corrected for a Cherenkov light attenuation in the tissue of the subject.

2. The system of claim 1 , wherein the surface layer of the tissue of the subject is sufficiently thick to include subsurface layers of the tissue of the subject from which Cherenkov emissions are emitted from the tissue of the subject, and is at least 5 millimeters (mm) thick.

3. The system of claim 2 , wherein the correction factor determination method is selected from the group consisting of:
calculating the optical Cherenkov correction factors based upon an electron density in the surface layers of the tissue of the subject as provided by the X-ray CT images, and
estimating a property map of the surface layers of the tissue of the subject from the MRI images and calculating the optical Cherenkov correction factors therefrom and
wherein the camera is configured to obtain reflectance images of a surface of the subject, the processor is configured to determine second correction factors (CF2) therefrom and to apply the CF2 to the images of Cherenkov emissions from the tissue of the subject to generate corrected Cherenkov emissions images, the corrected Cherenkov emissions images corrected for a skin attenuation of the Cherenkov emissions from the tissue of the subject.

4. The system of claim 3 , wherein the processor is configured to compare the corrected Cherenkov emissions images to a treatment plan of a dose delivery.

5. The system of claim 4 , wherein the processor is configured to shut off a radiation source if the corrected Cherenkov emissions images differ from the treatment plan by more than a threshold.

6. The system of claim 2 , wherein the correction factor determination method comprises determining a tissue type map of the surface layer of the tissue of the subject from the three-dimensional voxel-based images of the tissue of the subject of the subject and determining correction factors for the Cherenkov attenuation by the tissue type therefrom, and
wherein the camera is also configured to obtain reflectance images of a surface of the subject, the processor is configured to determine second correction factors (CF2) therefrom and to apply the CF2 to the images of Cherenkov emissions from the tissue of the subject to generate corrected Cherenkov emissions images, the corrected Cherenkov emissions images being corrected for a skin attenuation of the Cherenkov emissions from the tissue of the subject.

7. The system of claim 1 , wherein the correction factor determination method comprises calculating the optical Cherenkov correction factors from the electron density in the surface layer of the tissue of the subject as provided by the X-ray CT images.

8. The system of claim 1 , wherein the correction factor determination method comprises estimating an electron density map of the surface layer of the tissue of the subject from the MRI images and calculating the optical Cherenkov correction factors from the electron density map.

9. The system of claim 1 , wherein the correction factor determination method comprises determining a tissue type map of the surface layer of the tissue of the subject and determining the optical Cherenkov correction factors from the tissue type map.

10. A method of generating corrected images of Cherenkov emissions from a tissue exposed to radiation comprising:
making X-Ray computed tomography (CT) images or Magnetic Resonance Imaging (MRI) images of the tissue;
extracting a tissue surface volume from the X-Ray CT images or the MRI images;
determining correction factors CF in the tissue surface volume from the X-Ray CT images or the MRI images that correct images of Cherenkov emissions for a tissue absorbance;
obtaining images of Cherenkov emissions from the tissue as the tissue is exposed to radiation from a radiation beam source; and
using the correction factors to correct the images of Cherenkov emissions.

11. The method of claim 10 , further comprising obtaining reflectance images of a surface of the tissue, and using the reflectance images to further correct the images of Cherenkov emissions.

12. The method of claim 11 , wherein the X-Ray CT images or the MRI images are X-Ray CT images and the correction factors are determined from a CT density by a calculation from the CT density.

13. The method of claim 11 , wherein the X-Ray CT images or the MRI images are MM images and the correction factors are determined by using the MRI images to estimate an electron density map and a calculation from the electron density map.

14. The method of claim 11 , wherein tissue types in the tissue surface volume are classified from the X-Ray CT images or the MM images to generate a tissue type map, and the correction factors are determined according to the tissue type map.

15. A method for monitoring a radiation treatment comprising:
using the method of claim 12 to generate corrected images of Cherenkov emissions from the tissue being irradiated;
determining an actual applied dose map from the corrected images of Cherenkov emissions; and
comparing the actual applied dose map to a planned dose map.

16. A method for controlling a radiation treatment of a lesion in a subject comprising:
determining a treatment plan for the lesion in the subject comprising a planned dose map;
treating the lesion in the subject with radiation from a radiation beam source; using the method of claim 15 to verify an actual applied dose map corresponding to the planned dose map; and
if the actual applied dose map differs from the planned dose map by more than a threshold, turning off the radiation beam source.

17. A method for monitoring a radiation treatment comprising:
using the method of claim 13 to generate corrected images of Cherenkov emissions from the tissue being irradiated;
determining an actual appl

Assignees

• Dartmouth College

Inventors

• Hachadorian Rachael
• Pogue Brian
• Bruza Petr
• Jarvis Lesley

Classifications

• A61N5/1049

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

• A61N5/1048

  Monitoring, verifying, controlling systems and methods · CPC title

• A61N2005/1089

  Electrons · CPC title

• A61N2005/1087

  Ions; Protons · CPC title

• A61N5/10

  X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy (A61N5/01 takes precedence) · CPC title