# US 11,998,761 B2 · Radiation based treatment beam position calibration and verification

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- Number: US 11,998,761 B2
- Document ID: US11998761B2
- Status: Granted
- Kind: B2
- Application number: 18/297,723
- Filed: 2023-04-10
- Published: 2023-08-03
- Granted: 2024-06-04
- Earliest claimed: 2017-05-26
- Assignees: Accuray Incorporated
- Applicants: Accuray Incorporated
- Inventors: Warren Kilby; Petr Jordan; John Noll; Calvin Maurer, Jr.
- Web page: https://patentgrep.com/patent/US11998761B2

## CPC

- A61N 5/1075: {for testing, calibrating, or quality assurance of the radiation treatment apparatus}
- A61B 6/583: {using calibration phantoms}
- A61N 5/1043: {Scanning the radiation beam, e.g. spot scanning or raster scanning}
- A61N 5/1065: {Beam adjustment}
- A61N 5/1083: {Robot arm beam systems}
- A61N 2005/1076: {using a dummy object placed in the radiation field, e.g. phantom}
- A61N 2005/1091: {Kilovoltage or orthovoltage range photons}
- A61N: ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY (measurement of bioelectric currents A61B; surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body A61B18/00; anaesthetic apparatus in general A61M; incandescent lamps H01K; infrared radiators for heating H05B)
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

A method of calibration in a radiation delivery system. The method including acquiring, using a camera, an image of a radiation beam incident on a phantom, wherein the radiation beam being emitted by a radiation source of the radiation delivery system and the phantom comprising an X-ray luminescent material. The method further including determining a beam pointing offset based on the image. The method further including calibrating a position of the radiation source of the radiation delivery system based on the beam pointing offset and a relative position of the camera with respect to a beam axis of the radiation beam.

## Claims

### Claim 1

A method of calibration in a radiation delivery system, comprising:
acquiring, using a camera, an image of a radiation beam incident on a phantom, the radiation beam being emitted by a radiation source of the radiation delivery system, the phantom comprising an X-ray luminescent material,
determining a position of the camera based on a pattern overlaid on the X-ray luminescent material; and
calibrating a position of the radiation source of the radiation delivery system based on the image and the position of the camera.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
acquiring, using the camera, a second image of the radiation beam incident on the phantom subsequent to the calibrating of the position of the radiation source;
calculating a beam pointing error based on the second image and the image; and outputting the beam pointing error.

### Claim 3

A calibration system comprising:
a phantom comprising an X-ray luminescent material; a camera system of the calibration system to:
acquire an image of a radiation beam incident on the phantom, the radiation beam being emitted by a radiation source;
determine a beam pointing offset based on the image;
determine a position of the camera system based on a pattern overlaid on the X-ray luminescent material; and
calibrate a position of the radiation source based on the image and the position of the camera system.

### Claim 4 (depends on 3)

The calibration system of claim 3, wherein the camera system comprises one or more cameras, wherein the one or more cameras to:
acquire a first set of images of the phantom while the phantom is not being irradiated; acquire a second set of images of the radiation beam incident on the phantom,
the second set of images comprising the image, wherein determining the beam pointing offset is further based on the first set of images and the second set of images.

### Claim 5 (depends on 4)

The calibration system of claim 4, wherein:
each of the second set of images is of the radiation beam incident on an entrance surface of the phantom;
each of the one or more cameras is coupled to a head of the radiation source; and the camera system is further to:
determine a projected isocenter of the radiation source based on the first set of images, geometry of the phantom, and position of the phantom; and
determine a third centroid of the radiation beam incident on the phantom is based on the second set of images, wherein the beam pointing offset is based on comparing the projected isocenter and the third centroid.

### Claim 6 (depends on 4)

The calibration system of claim 4, wherein:
each of the second set of images is a super-position of the radiation beam incident on an entrance surface and an exit surface of the phantom;
the one or more cameras are coupled to a head of the radiation source; and the camera system is further to:
determine a projected isocenter of the radiation source based on the first set of images, geometry of the phantom, and position of the phantom; and
determine a half-way point between a first centroid of the radiation beam incident on the entrance surface and a second centroid of the radiation beam incident on the exit surface is based on the second set of images, wherein the beam pointing offset is based on a distance between the projected isocenter and the half-way point.

### Claim 7 (depends on 4)

The calibration system of claim 4, wherein:
the second set of images is of the radiation beam incident on an entrance surface of the phantom;
the one or more cameras is a plurality of cameras that are positioned at static locations; the camera system is further to:
determine a center, triangulated in 3D, of the radiation beam incident on the phantom based on the second set of images, wherein the beam pointing offset is based on the center triangulated in 3D and a location of a source of the radiation beam.

### Claim 8 (depends on 4)

The calibration system of claim 4, wherein:
the second set of images are used to generate super-position of the radiation beam incident on an entrance surface and an exit surface of the phantom;
the one or more cameras is a plurality of cameras that are positioned at static locations;
the camera system is further to:
determine a projected isocenter of the radiation source is based on the first set of images, geometry of the phantom, and position of the phantom; and
determine a first center, triangulated in 3D, of the radiation beam incident on the entrance surface and a second center, triangulated in 3D, of the radiation beam incident on the exit surface are based on the second set of images, wherein the beam pointing offset is based on the first center triangulated in 3D, the second center triangulated in 3D, and the projected isocenter.

### Claim 9 (depends on 4)

The calibration system of claim 4, wherein:
the one or more cameras have sensor distortion and lens distortion; and
the camera system is to apply corrections for at least one of the sensor distortion or the lens distortion to the first set of images and the second set of images.

### Claim 10 (depends on 3)

The calibration system of claim 3, wherein the camera system is further to:
acquire a second image of the radiation beam incident on the phantom subsequent to the calibrating of the position of the radiation source; and
calculate a beam pointing error based on a third image and the image; and output the beam pointing error.