Method and system for adjusting focal point position

1. A method implemented on at least one device including at least one processor and at least one computer-readable storage medium, the method comprising:

obtaining a first thermal capacity of an anode of an X-ray tube and a first position of a focal point of the X-ray tube;

obtaining a second thermal capacity of the anode of the X-ray tube, wherein the second thermal capacity is different from the first thermal capacity;

obtaining a first relationship between a position of the focal point and a thermal capacity of the anode of the X-ray tube;

determining a second position of the focal point of the X-ray tube based on the second thermal capacity and the first relationship;

determining a target grid voltage difference of a focusing cup of the X-ray tube based on the first position and the second position of the focal point, wherein the target grid voltage difference is a difference between a first grid voltage of a first section of the focusing cup and a second grid voltage of a second section of the focusing cup; and

adjusting the grid voltage difference of the focusing cup based on the target grid voltage difference.

2. The method of claim 1 , wherein the first thermal capacity is a reference thermal capacity and the second thermal capacity is a working thermal capacity.

3. The method of claim 1 , wherein the first thermal capacity ranges between 0 and 20 percent of a maximum thermal capacity of the anode of the X-ray tube.

4. The method of claim 1 , wherein the obtaining a first relationship between a position of the focal point and a thermal capacity of the anode of the X-ray tube comprises:

obtaining a plurality of training thermal capacities of the anode of the X-ray tube;

obtaining a plurality of training positions of the focal point of the X-ray tube, wherein each of the plurality of training positions of the focal point of the X-ray tube corresponds to one of the plurality of training thermal capacities of the anode of the X-ray tube, respectively; and

identifying the first relationship based on the plurality of training thermal capacities of the anode of the X-ray tube and the plurality of corresponding training positions of the focal point of the X-ray tube.

5. The method of claim 4 , wherein the obtaining a plurality of training positions of the focal point comprises:

measuring a training position of the focal point via a pin hole in a collimator of the X-ray tube.

6. The method of claim 4 , wherein the identifying the first relationship comprises:

performing mapping, curve fitting, interpolating, or machine learning based on the plurality of training thermal capacities of the anode of the X-ray tube and the plurality of corresponding training positions of the focal point of the X-ray tube.

7. The method of claim 4 , wherein the obtaining a first position of the focal point of an X-ray tube comprises:

determining the first position of the focal point based on the thermal capacity and the first relationship.

8. The method of claim 1 , wherein the determining a second position of the focal point comprises:

obtaining two training thermal capacities of the anode of the x-ray tube, wherein a first training thermal capacity of the two training capacities is greater than the second thermal capacity and a second training thermal capacity of the two training capacities is less than the second thermal capacity;

obtaining two training positions of the focal point of the X-ray tube corresponding to the two training thermal capacities of the anode of the X-ray tube; and

determining, using a linear interpolation method, the second position of the X-ray tube based on the second thermal capacity of the anode of the X-ray tube, the two training thermal capacities of the anode of the X-ray tube, and the two corresponding training positions of the focal point of the X-ray tube.

9. The method of claim 1 , wherein the determining a target grid voltage difference of a focusing cup of the X-ray tube comprises:

obtaining a second relationship between a grid voltage difference of the focusing cup of the X-ray tube and a position of the focal point of the X-ray tube; and

determining the target grid voltage difference of the focusing cup of the X-ray tube based on the first position and the second position of the focal point of the X-ray tube and the second relationship.

10. The method of claim 1 , wherein the adjusting the grid voltage difference of the focusing cup comprises adjusting the focal point of the X-ray tube from the second position to the first position.

11. A system, comprising:

at least one computer-readable storage medium including a set of instructions; and

at least one processor in communication with the at least one computer-readable medium, wherein when executing the set of instructions, the system is caused to:

obtain a first thermal capacity and a second thermal capacity of an anode of an X-ray tube, wherein the second thermal capacity is different from the first thermal capacity;

obtain a first position of a focal point of the X-ray tube;

obtain a first relationship between a position of the focal point and a thermal capacity of the anode of the X-ray tube;

determine a second position of the focal point of the X-ray tube based on the second thermal capacity and the first relationship;

determine a target grid voltage difference of a focusing cup of the X-ray tube based on the first position and the second position of the focal point, wherein the target grid voltage difference is a difference between a first grid voltage of a first section of the focusing cup and a second grid voltage of a second section of the focusing cup; and

adjust the grid voltage difference of the focusing cup based on the target grid voltage difference.

12. The system of claim 11 , wherein the first thermal capacity is a reference thermal capacity and the second thermal capacity is a working thermal capacity.

13. The system of claim 11 , wherein to obtain the first relationship between a position of the focal point and a thermal capacity of the anode of the X-ray tube, the system is caused to:

obtain a plurality of training thermal capacities of the anode of the X-ray tube;

obtain a plurality of training positions of the focal point of the X-ray tube, wherein each of the plurality of training positions of the focal point of the X-ray tube corresponds to one of the plurality of training thermal capacities of the anode of the X-ray tube, respectively; and

identify the first relationship based on the plurality of training thermal capacities of the anode of the X-ray tube and the plurality of corresponding training positions of the focal point of the X-ray tube.

14. The system of claim 13 , wherein to obtain a plurality of training positions of the focal point of the X-ray tube, the system is caused to:

measure a training position of the focal point via a pin hole in a collimator of the X-ray tube.

15. The system of claim 13 , wherein to identify the first relationship, the system is caused to:

perform mapping, curve fitting, interpolating, or machine learning based on the plurality of training thermal capacities of the anode of the X-ray tube and the plurality of corresponding training positions of the focal point of the X-ray tube.

16. The system of claim 11 , wherein to determine a target grid voltage difference of a focusing cup of the X-ray tube, the system is caused to:

obtain a second relationship between a grid voltage difference of the focusing cup of the X-ray tube and a position of the focal point; and

determine the target grid voltage difference of the focusing cup of the X-ray tube based on the first position and the second position of the focal point of an X-ray tube and the second relationship.

17. The system of claim 11 , wherein to adjust the grid voltage difference of the focusing cup, the system is caused to:

adjust the focal point of the X-ray tube from the second position to the first position.

18. A non-transitory computer readable medium storing instructions, the instructions, when executed by a computer, causing the computer to implement a method, comprising:

obtaining a first thermal capacity of an anode of an X-ray tube and a first position of a focal point of the X-ray tube;

obtaining a second thermal capacity of the anode of the X-ray tube, wherein the second thermal capacity is different from the first thermal capacity;

obtaining a first relationship between a position of the focal point and a thermal capacity of the anode of the X-ray tube;

determining a second position of the focal point of the X-ray tube based on the second thermal capacity and the first relationship;

determining a target grid voltage difference of a focusing cup of the X-ray tube based on the first position and the second position of the focal point, wherein the target grid voltage difference is a difference between a first grid voltage of a first section of the focusing cup and a second grid voltage of a second section of the focusing cup; and

adjusting the grid voltage difference of the focusing cup based on the target grid voltage difference.