System and method for correcting position errors of a multi-leaf collimator

Patent metadata

Field	Value
Publication number	US-11065472-B2
Application number	US-201916547488-A
Country	US
Kind code	B2
Filing date	Aug 21, 2019
Priority date	Aug 22, 2018
Publication date	Jul 20, 2021
Grant date	Jul 20, 2021

Abstract

Methods and systems for correcting position errors for a multi-leaf collimator (MLC) are provided. A method may include determining a first position for each of the plurality of leaves. The information associated with the first position may include a first movement direction and a first angle. A movement of the each of the plurality of leaves along the first movement direction may be configured to move toward or away from a center of the radiation field. The method may also include determining an offset value associated with the first position based on the first angle and the first movement direction; and determining a target position of the each of the plurality of leaves based on the offset value.

First claim

We claim:

1. A method implemented on a computing device having at least one processor and at least one computer-readable storage medium for correcting position errors for a multi-leaf collimator (MLC), the MLC including a plurality of leaves to shape a radiation field, each of the plurality of leaves being associated with a driving component including a main encoder, the method comprising:
determining a first position for each of the plurality of leaves, information associated with the first position including a first movement direction and a first angle, wherein a movement of the each of the plurality of leaves along the first movement direction is configured to move toward or away from a center of the radiation field;
obtaining a first reference offset value associated with the first position of the each of the plurality of leaves from a pre-determined offset table;
determining an offset value associated with the first position based on the first angle, the first movement direction, and the first reference offset value; and
determining a target position of the each of the plurality of leaves based on the offset value.

2. The method of claim 1 , wherein the determining a first position for each of the plurality of leaves includes:
obtaining an angle of a gantry corresponding to the first position of the each of the plurality of leaves;
obtaining an angle of a collimator corresponding to the first position of the each of the plurality of leaves, wherein the MLC is mounted in the collimator and rotates along with the collimator; and
determining the first angle of the each of the plurality of leaves based on the angle of the gantry and the angle of the collimator.

3. The method of claim 1 , wherein the determining a first position for each of the plurality of leaves includes:
obtaining a first velocity relating to the driving component;
in response to a determination that the first velocity relating to the driving component is lower than a first threshold, determining the first movement direction as a backward movement direction, the each of the plurality of leaves being configured to move away from the center of the radiation field along the backward movement direction; and
in response to a determination that the first velocity relating to the driving component is greater than a second threshold, determining the first movement direction as a forward movement direction, the each of the plurality of leaves being configured to move toward the center of the radiation field along the forward movement direction.

4. The method of claim 1 , wherein the determining a target position of the each of the plurality of leaves based on the offset value includes:
subtracting the offset value from a preprogrammed position of the each of the plurality of leaves.

5. The method of claim 1 , wherein the information associated with the first position includes a first main encoder value, the determining an offset value associated with the first position based on the first angle, the first movement direction, and the first reference offset value includes:
obtaining a first main encoder value corresponding to the first position of the each of the plurality of leaves, the first main encoder value being acquired by the main encoder;
obtaining a second main encoder value corresponding to a second position of the each of the plurality of leaves, the second main encoder value being acquired by the main encoder, and the second position being a position at where a movement direction of the each of the plurality of leaves changes from a second movement direction to the first movement direction; and
determining the offset value associated with the first position based on the first movement direction, the first reference offset value, and a difference between the first main encoder value and the second main encoder value.

6. The method of claim 5 , wherein the determining the offset value associated with the first position based on the first movement direction, the first reference offset value, and a difference between the first main encoder value and the second main encoder value includes:
if the each of the plurality of leaves moves away from the center of the radiation field along the first movement direction, designating a minimum value among the first reference offset value and a sum of a second reference offset value associated with the second position and the difference between the first main encoder value and the second main encoder value as the offset value associated with the first position; and
if the each of the plurality of leaves moves toward the center of the radiation field along the first movement direction, designating a maximum value among the first reference offset value and a sum of the second reference offset value associated with the second position and the difference between the first main encoder value and the second main encoder value as the offset value associated with the first position.

7. The method of claim 1 , wherein the determining an offset value associated with the first position based on the first angle, the first movement direction, and the first reference offset value includes:
if the each of the plurality of leaves moves toward the center of the radiation field along the first movement direction and the first angle is equal to 0 degrees, designating the offset value associated with the first position as 0.

8. The method of claim 1 , wherein the determining a target position of the each of the plurality of leaves based on the offset value includes:
obtaining a first main encoder value corresponding to a first position of each of the plurality of leaves acquired by the main encoder; and
correcting the first main encoder value based on the offset value to obtain the target position of the each of the plurality of leaves.

9. The method of claim 8 , wherein the correcting the first main encoder value based on the offset value includes:
adding the offset value to the first main encoder value to obtain the target position of the each of the plurality of leaves.

10. A method implemented on a computing device having at least one processor and at least one computer-readable storage medium for correcting position errors for a multi-leaf collimator (MLC), the MLC including a plurality of leaves to shape a radiation field, each of the plurality of leaves being associated with a driving component including a main encoder, the method comprising:
determining a first position for each of the plurality of leaves, information associated with the first position including a first movement phase, wherein a movement of the each of the plurality of leaves moves in the first movement phase is configured to move toward or away from a center of the radiation field;
determining an offset value associated with the first position based on the first movement phase; and
determining a target position of the each of the plurality of leaves based on the offset value;
wherein the first movement phase associated with the first position of each of the plurality of leaves is determined based on a difference between a first measurement value and a second measurement value acquired by one of the main encoder and an auxiliary encoder in two adjacent sampling periods.

11. The method of claim 10 , wherein
the first measurement value corresponds to the first position, the auxiliary encoder is associated with each of the plurality of leaves and configured to determine a position of each of the plurality of leaves; and
the first movement phase includes one of:
a first phase in which the each of the plurality of leaves is moving toward the center of the radiation field;
a second phase in which the each of the

Assignees

• Shanghai United Imaging Healthcare Co Ltd

Inventors

• Ma Boqi
• Li Zihan
• Chen Yujie
• Yu Lang

Classifications

• G21K1/046

  varying the contour of the field, e.g. multileaf collimators · CPC title

• A61N5/1048 Primary

  Monitoring, verifying, controlling systems and methods · CPC title

• A61N5/1045 Primary

  using a multi-leaf collimator, e.g. for intensity modulated radiation therapy or IMRT · CPC title

• A61N5/103

  Treatment planning systems · CPC title

• A61N5/1081

  Rotating beam systems with a specific mechanical construction, e.g. gantries · CPC title