Bolus tracking

1. A CT scanning method of bolus tracking, in which multiple CT scans are performed on a region of interest (ROI) of a subject while a contrast agent is injected into the subject, to perform a tracking process of the contrast agent, the method comprising:

obtaining a first CT value of the ROI of the subject for a (i−1)-th CT scan, wherein i is an integer greater than or equal to 2;

obtaining a second CT value of the ROI of the subject for an i-th CT scan, wherein a first CycleTime Ti i−1 represents a duration between a start of the i-th CT scan and a start of the (i−1)-th CT scan, and T 1 is preset;

determining whether the second CT value is no less than a target threshold; and

in response to determining that the second CT value is less than the target threshold,

determining an interval required to increase the second CT value to the target threshold according to the second CT value, the first CT value and the first CycleTime T i−1 ;

setting a second CycleTime T i according to the interval and the first CycleTime T i−1 , wherein the second CycleTime T i represents a duration between the start of the i-th CT scan and a start of a (i+1)-th CT scan; and

performing the (i+1)-th CT scan according to the second CycleTime T i ,

wherein setting the second CycleTime T i according to the interval and the first CycleTime T i−1 comprises:

in response to determining that the interval is greater than 2*T i−1 , setting the second CycleTime T i to be a value greater than the first CycleTime T i−1 .

2. The method of claim 1 , wherein the value greater than the first CycleTime T i−1 is a sum of the first CycleTime T i−1 and a preset variable, and

wherein the preset variable decreases gradually as a number of CT scans performed on the ROI of the subject increases.

3. The method of claim 1 , wherein the first CycleTime T i−1 is increased according to a preset ratio to obtain the value greater than the first CycleTime T i−1 , and

wherein the preset ratio decreases gradually as a number of CT scans performed on the ROI of the subject increases.

4. The method of claim 1 , wherein setting the second CycleTime T i according to the interval and the first CycleTime T i−1 comprises:

in response to determining that the interval is greater than T i−1 and less than 2*T i−1 , setting the second CycleTime T i , to be the first CycleTime T i−1 .

5. The method of claim 1 , wherein setting the second CycleTime T i according to the interval and the first CycleTime T i−1 comprises:

in response to determining that the interval is less than T i−1 , setting the second CycleTime T i to be the interval.

6. The method of claim 1 , wherein determining the interval according to the second CT value, the first CT value and the first CycleTime T i−1 comprises:

obtaining a CT value increasing speed according the second CT value, the first CT value and the first CycleTime T i−1 ; and

determining the interval according to the CT value increasing speed, the second CT value, and the target threshold.

7. The method of claim 1 , further comprising:

before injecting the contrast agent into the subject, performing a pilot scan on the subject to obtain a pilot image and determining the ROI according to the pilot image.

8. The method of claim 1 , further comprising:

determining that the tracking process is finished when a CT value of the ROI of the subject obtained for a CT scan is no less than the target threshold, and in response,

stopping injecting the contrast agent and performing a routine CT scan to obtain a CT image of the ROI for diagnosis.

9. The method of claim 1 , wherein, for each of the CT scans, a CT value of the ROI is a mean value of respective CT values of pixels in the ROI.

10. A device for bolus tracking, comprising:

at least one processor; and

at least one non-transitory machine-readable storage medium coupled to the at least one processor having machine-executable instructions stored thereon that, when executed by the at least one processor, cause the at least one processor to perform operations for bolus tracking, in which multiple CT scans are performed on a region of interest (ROI) of a subject while a contrast agent is injected into the subject, to perform a tracking process of the contrast agent, the operations comprising:

obtaining a first CT value of a ROI of a subject for a (i−1)-th CT scan, wherein i is an integer greater than or equal to 2;

obtaining a second CT value of the ROI of the subject for an i-th CT scan, wherein a first CycleTime T i−1 represents a duration between a start of the i-th CT scan and a start of the (i−1)-th CT scan, and T 1 is preset;

determining whether the second CT value is no less than a target threshold;

in response to determining that the second CT value is greater than or equal to the target threshold, ending the tracking process; and

in response to determining that the second CT value is less than the target threshold,

determining an interval required to increase the second CT value to the target threshold according to the second CT value, the first CT value and the first CycleTime T i−1 ,

setting a second CycleTime T i according to the interval and the first CycleTime T i−1 , wherein the second CycleTime T i represents a duration between the start of the i-th CT scan and a start of a (i+1)-th CT scan; and

performing the (i+1)-th CT scan according to the second CycleTime T i ,

wherein setting the second CycleTime T i according to the interval and the first CycleTime T i−1 comprises:

in response to determining that the interval is greater than 2*T i−1 , setting the second CycleTime T i to be a value greater than the first CycleTime T i−1 .

11. The device of claim 10 , wherein the value greater than the first CycleTime T i−1 is a sum of the first CycleTime and a preset variable, and

wherein the preset variable decreases gradually as a number of CT scans performed on the ROI of the subject increases.

12. The device of claim 10 , wherein the first CycleTime T i−1 is increased according to a preset ratio to obtain the value greater than the first CycleTime T i−1 , and

wherein the preset ratio decreases gradually as a number of CT scans performed on the ROI of the subject increases.

13. The device of claim 10 , wherein setting the second CycleTime T i according to the interval and the first CycleTime T i−1 comprises:

in response to determining that the interval is greater than T i−1 and less than 2*T i−1 , setting the second CycleTime T i to be the first CycleTime T i−1 .

14. The device of claim 10 , wherein setting the second CycleTime T i according to the interval and the first CycleTime T i−1 comprises:

in response to determining that the interval is less than T i−1 , setting the second CycleTime T i to be the interval.

15. The device of claim 10 , wherein determining the interval according to the second CT value, the first CT value and the first CycleTime T i−1 comprises:

obtaining a CT value increasing speed according the second CT value, the first CT value and the first CycleTime T i−1 ; and

determining the interval according to the CT value increasing speed, the second CT value, and the target threshold.

16. The device of claim 10 , wherein the operations further comprise:

before injecting the contrast agent into the subject, performing a pilot scan on the subject to obtain a pilot image and determining the ROI according to the pilot image.

17. The device of claim 10 , wherein the operations further comprise:

in response to determining that the tracking process is finished, stopping injecting the contrast agent and performing a routine CT scan to obtain a CT image of the ROI for diagnosis.

18. The device of claim 10 , wherein, for each of the CT scans, a CT value of the ROI is a mean value of respective CT values of pixels in the ROI.