Adaptive control of sampling frequency for computed tomography
A method of contrast-enhanced computed tomography (CT) imaging can include repeatedly scanning a target region at a frequency during a session, the frequency initially being a first rate. After detecting an increase of the attenuation of radiation by a contrast-enhanced first structure within a target region, the frequency can be increased to a second rate. After detecting a subsequent decrease in the attenuation, the frequency can be decreased to a third rate.
1. A method of contrast-enhanced computed tomography (CT) imaging, comprising:
(a) repeatedly scanning a target region at a frequency during a session of multiple complete scans, each scan in the session of multiple complete scans comprising emitting x-ray radiation toward the target region from a plurality of angular views, the frequency at which complete scans are performed in the session initially being a first rate;
(b) monitoring, during the session of multiple complete scans, an indicator of attenuation of radiation by a contrast-enhanced first structure within the target region;
(d) after detecting an increase of the attenuation, increasing the frequency at which complete scans are performed in the session to a second rate; and
(e) after detecting a decrease in the attenuation after (d), decreasing the frequency at which complete scans are performed in the session to a third rate.
2. The method of claim 1 , further comprising generating a representation of a relationship between time and radiation attenuation by a second structure within the target region.
3. The method of claim 2 , wherein the radiation attenuation by the second structure with respect to time represents an indicator of vascular perfusion of the second structure.
4. The method of claim 1 , wherein the frequency is increased to the second rate in response to detection of a decrease in a rate at which the attenuation is increasing.
5. The method of claim 4 , further comprising beginning monitoring of the rate of change after detecting an increase of the attenuation to or beyond a threshold.
6. The method of claim 1 , further comprising decreasing the frequency below the third rate in response to detection of a decrease in a rate at which the attenuation is decreasing.
7. The method of claim 6 , wherein decreasing the frequency below the third rate comprises reducing the frequency with each successive scan.
8. The method of claim 1 , wherein the frequency is reduced to the third rate upon a first detection of a decrease in attenuation after (d).
9. The method of claim 1 , wherein the structure comprises at least one of a heart chamber, an aorta, or another blood vessel.
10. The method of claim 1 , further comprising monitoring of a rate of change of the attenuation.
11. A computer-implemented system for controlling contrast-enhanced computed tomography imaging, comprising:
an attenuation monitoring module configured to monitor, during an imaging session comprising multiple complete scans wherein each complete scan comprises emitting x-ray radiation toward a target region from a plurality of angular views, an indicator of attenuation of radiation by a contrast-enhanced structure within the target region;
a scanning-frequency control module configured to (i) increase a frequency at which complete scans are performed in the imaging session from a first rate to a second rate after detection of an increase of the attenuation, and (ii) decrease the frequency to a third rate after detecting a decrease in attenuation after increasing the frequency to the second rate.
12. The computer-implemented system of claim 11 , wherein the scanning-frequency control module is further configured to increase the frequency to the second rate in response to detection of a decrease in a rate at which the attenuation is increasing.
13. The computer-implemented system of claim 11 , wherein the monitoring module is further configured to begin monitoring of the rate of change after detection of compliance of the attenuation with a threshold.
14. The computer-implemented system of claim 11 , further comprising a processing module configured to generate a representation of a relationship between time and radiation attenuation by a second structure within the target region.
15. The computer-implemented system of claim 14 , wherein the radiation attenuation by the second structure with respect to time represents an indicator of vascular perfusion of the second structure.
16. The computer-implemented system of claim 11 , wherein the scanning-frequency control module is further configured to decrease the frequency below the third rate in response to detection of a decrease in a rate at which the attenuation is decreasing.
17. The computer-implemented system of claim 11 , wherein the scanning-frequency control module is further configured to reduce the frequency to the third rate upon a first detection of a decrease in attenuation after an increase to the second rate.
18. The computer-implemented system of claim 11 , wherein the monitoring module is further configured to monitor a rate of change of the attenuation.
19. A method of computed tomography imaging, comprising:
repeatedly scanning a target region at a scan frequency during a session, each scan in the session comprising emitting x-ray radiation into the target region from a plurality of angular views to produce a complete scan;
monitoring, during the session, an indicator of attenuation of radiation by a contrast-enhanced first structure within the target region; and
varying the scan frequency based on the attenuation.
20. The method of claim 19 , wherein x-ray radiation is emitted at a minimum frequency when the attenuation is below a low threshold and at a maximum frequency when then attenuation is above a high threshold.