# US 11,077,322 B2 · Systems and methods for calibrating radiation device

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- Number: US 11,077,322 B2
- Document ID: US11077322B2
- Status: Granted
- Kind: B2
- Application number: 16/565,632
- Filed: 2019-09-10
- Published: 2020-03-12
- Granted: 2021-08-03
- Earliest claimed: 2018-09-12
- Assignees: Shanghai United Imaging Healthcare Co., Ltd.
- Applicants: Shanghai United Imaging Healthcare Co., Ltd.
- Inventors: Hongcheng Yang
- Web page: https://patentgrep.com/patent/US11077322B2

## CPC

- A61N 5/1075: {for testing, calibrating, or quality assurance of the radiation treatment apparatus}
- A61N 5/1045: {using a multi-leaf collimator, e.g. for intensity modulated radiation therapy or IMRT}
- A61N 5/1049: {for verifying the position of the patient with respect to the radiation beam}
- A61N 5/1067: {in real time, i.e. during treatment}
- A61N 2005/1054: {using a portal imaging system}
- A61N 2005/1074: {Details of the control system, e.g. user interfaces}
- 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)

## Abstract

The present disclosure is related to systems and methods for calibrating a radiation device. The method includes obtaining a plurality of images acquired at each of at least one source-to-image distance (SID) by the imaging device. The method includes determining, based on the plurality of images, at least one first projection position of a first axis of the collimator on the imaging device and at least one second projection position of a second axis of the radiation beam on the imaging device. The method includes determining, based on the at least one first projection position and the at least one second projection position, at least one offset distance between the first projection position and the second projection position. The method includes determining whether to calibrate the radiation device by comparing the at least one offset distance with a threshold.

## Claims

### Claim 1

A method for calibrating a radiation device implemented on a computing device having one or more processors and one or more storage devices, the radiation device includes a radiation source, a collimator, and a detector of an imaging device disposed opposite to the radiation source, the radiation source being configured to emit a radiation beam, the collimator being configured to block the radiation beam, the method comprising:
obtaining a plurality of images acquired at a source-to-image distance (SID) by the imaging device, wherein the plurality of images include at least one first image and at least one second image, the at least one first image is obtained by rotating the collimator around a first axis of the collimator, and the at least one second image is obtained by imaging a phantom from at least one gantry angle;
determining, based on the at least one first image, a first projection position of the first axis of the collimator on the imaging device;
determining, based on the at least one second image, a second projection position of a second axis of the radiation beam on the imaging device;
determining, based on the first projection position and the second projection position, an offset distance between the first projection position and the second projection position; and
determining whether to calibrate the radiation device by comparing the offset distance with a threshold.

### Claim 2 (depends on 1)

The method of claim 1, wherein determining whether to calibrate the radiation device by comparing the offset distance with a threshold comprises determining that the offset distance exceeds the threshold, and the method further comprising:
calibrating the radiation device by adjusting at least one component of the radiation device.

### Claim 3 (depends on 1)

The method of claim 1, wherein the at least one first image includes a projection image of at least one of a marker board, a jaw, or a multi-leaf collimator.

### Claim 4 (depends on 1)

The method of claim 1, wherein the at least one second image includes a projection image of the phantom.

### Claim 5 (depends on 1)

The method of claim 1, wherein the imaging device is an electronic portal imaging device (EPID).

### Claim 6

A method for calibrating a radiation device implemented on a computing device having one or more processors and one or more storage devices, the radiation device includes a radiation source, a collimator, and a detector of an imaging device disposed opposite to the radiation source, the radiation source being configured to emit a radiation beam, the collimator being configured to block the radiation beam, the method comprising:
obtaining a plurality of images acquired at each source-to-image distances (SID) of a plurality of SIDs by the imaging device, wherein the plurality of images include at least one first image and at least one second image, the at least one first image is obtained by rotating the collimator around the first axis of the collimator, and the at least one second image is obtained by imaging a phantom from at least one gantry angle;
determining, based on the at least one first image, a first projection position of a first axis of the collimator on the imaging device associated with the each SID of the plurality of SIDs;
determining, based on the at least one second image, a second projection position of a second axis of the radiation beam on the imaging device associated with the each SID of the plurality of SIDs;
determining, based on the first projection position of the first axis of the collimator on the imaging device associated with the each SID of the plurality of SIDs and the second projection position of the second axis of the radiation beam on the imaging device associated with the each SID of the plurality of SIDs, an offset distance associated with the each SID of the plurality of SIDs; and
determining, based on the plurality of SIDs and the offset distance associated with the each SID of the plurality of SIDs, a deviation between the first axis of the collimator and the second axis of the radiation beam.

### Claim 7 (depends on 6)

The method of claim 6, wherein the at least one first image includes a projection image of at least one of a marker board, a jaw, or a multi-leaf collimator.

### Claim 8 (depends on 6)

The method of claim 6, wherein the at least one second image includes a projection image of a phantom.

### Claim 9 (depends on 6)

The method of claim 6, wherein the deviation between the first axis of the collimator and the second axis of the radiation beam includes at least one of
an angle of inclination of the first axis of the collimator relative to the second axis of the radiation beam, or
an offset of the first axis of the collimator relative to the second axis of the radiation beam.

### Claim 10 (depends on 9)

The method of claim 9, wherein the offset of the first axis of the collimator relative to the second axis of the radiation beam includes an offset distance between a first projection position of the first axis of the collimator and a second projection position of the second axis of the radiation beam on a target plane of the imaging device.

### Claim 11 (depends on 9)

The method of claim 9, wherein determining, based on the plurality of SIDs and the plurality of offset distances, the deviation between the first axis of the collimator and the second axis of the radiation beam comprises:
determining, based on the plurality of SIDs, the plurality of offset distances, and a geometric relationship between the plurality of SIDs and the plurality of offset distances, at least one of an angle of inclination of the first axis of the collimator relative to the second axis of the radiation beam or an offset of the first axis of the collimator relative to the second axis of the radiation beam.

### Claim 12 (depends on 9)

The method of claim 9, wherein determining, based on the plurality of SIDs and the plurality of offset distances, the deviation between the first axis of the collimator and the second axis of the radiation beam comprises:
determining, based on the plurality SIDs, the plurality of offset distances, and a geometric relationship between the plurality of SIDs and the plurality of offset distances, at least one of a plurality of initial angles of inclination of the first axis of the collimator relative to the second axis of the radiation beam or a plurality of initial offsets of the first axis of the collimator relative to the second axis of the radiation beam; and
determining, by performing a fitting operation based on at least one of the plurality of initial angles of inclination of the first axis of the collimator relative to the second axis of the radiation beam or the plurality of initial offsets of the first axis of the collimator relative to the second axis of the radiation beam, at least one of a target angle of inclination of the first axis of the collimator relative to the second axis of the radiation beam or a target offset of the first axis of the collimator relative to the second axis of the radiation beam.

### Claim 13 (depends on 6)

The method of claim 6, further comprising:
determining whether to calibrate the radiation device by comparing the deviation between the first axis of the collimator and the second axis of the radiation beam with a threshold.

### Claim 14 (depends on 13)

The method of claim 13, wherein determining whether to calibrate the radiation device by comparing the deviation between the first axis of the collimator and the second axis of the radiation beam with a threshold comprises determining that the deviation exceeds the threshold, and the method further comprising:
calibrating the radiation device by adjusting at least one component of the radiation device.

### Claim 15 (depends on 6)

The method of claim 6, wherein the imaging device is an electronic portal imaging device (EPID).

### Claim 16

A method for calibrating a radiation device implemented on a computing device having one or more processors and one or more storage devices, the radiation device includes a radiation source, a collimator, and a detector of an imaging device disposed opposite to the radiation source, the radiation source being configured to emit a radiation beam, the collimator being configured to block the radiation beam, the method comprising:
obtaining at least one first image acquired at a first source-to-image distance (SID) by the imaging device;
obtaining at least one second image acquired at a second SID by the imaging device, wherein the at least one first image and the at least one second image are obtained by rotating the collimator around the first axis of the collimator;
determining at least one projection position of a first axis of the collimator on the imaging device based on the at least one first image and the at least one second image, the at least one projection position of the first axis of the collimator on the imaging device includes a first projection position of the first axis of the collimator on the imaging device when the imaging device is positioned to acquire the at least one first image at the first SID, and a second projection position of the first axis of the collimator on the imaging device when the imaging device is positioned to acquire the at least one second image at the second SID;
obtaining at least one third image acquired at the first SID by the imaging device;
obtaining at least one fourth image acquired at the second SID by the imaging device, wherein the at least one third image and the at least one fourth image are obtained by imaging a phantom from at least one gantry angle;
determining at least one projection position of a second axis of the radiation beam on the imaging device based on the at least one third image and the at least one fourth image, the at least one projection position of the second axis of the radiation beam on the imaging device includes a third projection position of the second axis of the radiation beam on the imaging device when the imaging device is positioned to acquire the at least one third image at the first SID, and a fourth projection position of the second axis of the radiation beam on the imaging device when the imaging device is positioned to acquire the at least one fourth image at the second SID;
determining, based on the at least one first image and the at least one third image, a first offset distance between the first projection position and the third projection position;
determining, based on the at least one second image and the at least one fourth image, a second offset distance between the second projection position and the fourth projection position; and
determining, based on the first offset distance, the second offset distance, the first SID, and the second SID, a deviation between the first axis of the collimator and the second axis of the radiation beam.

### Claim 17 (depends on 3)

The method of claim 3, wherein a rotation center of the at least one of the marker board, the jaw, or the multi-leaf collimator in the at least one first image is determined as the first projection position of the first axis of the collimator on the imaging device.

### Claim 18 (depends on 1)

The method of claim 1, wherein the phantom includes a plurality of markers, and the determining, based on the at least one second image, a second projection position of a second axis of the radiation beam on the imaging device associated with the each SID of the plurality of SIDs comprises:
obtaining marker coordinates in a phantom coordinate system of the plurality of markers of the phantom;
obtaining projection coordinates of the plurality of markers in an image coordinate system;
determining a plurality of projection matrices of the phantom coordinate system based on the marker coordinates of the plurality of markers in the phantom coordinate system and the projection coordinates of the plurality of markers in the image coordinate system;
determining a transformation matrix between the phantom coordinate system and a coordinate system of a radiation system based on at least some of the plurality of projection matrices of the phantom coordinate system;
determining a plurality of projection matrices of the coordinate system of the radiation system based on the plurality of projection matrices of the phantom coordinate system and the transformation matrix; and
determining the second projection position of the second axis of the radiation beam on the imaging device based on the plurality of projection matrices of the coordinate system of the radiation system.