Temperature compensation for thin film transistors in digital X-ray detectors
A digital radiographic detector uses predetermined calibration information corresponding to a first operating temperature of the detector. The calibration data is accessible by the detector to compensate a radiographic image captured by the detector at a second operating temperature different than the first operating temperature. The operating temperature of the detector is monitored at approximately the time at which the radiographic image is captured at the second temperature.
1. A method of operating a digital radiographic detector having a plurality of pixels, the method comprising:
determining and electronically storing a gain calibration table applicable to the plurality of pixels in the detector at a first temperature;
capturing radiographic image data using the plurality of pixels in the detector at a second temperature different from the first temperature;
adjusting the gain calibration table based on the second temperature;
applying the adjusted gain calibration table to the radiographic image data captured at the second temperature; and
reading out the radiographic image data from the detector after the step of applying the adjusted gain calibration table thereto.
2. The method of claim 1 , further comprising predetermining a channel resistance factor, wherein the channel resistance factor is associated with a temperature dependency of channel resistance of each of the plurality of pixels in the detector, and wherein the step of adjusting comprises uniformly adjusting the gain calibration table using the channel resistance factor.
3. The method of claim 2 , wherein the channel resistance factor and the gain calibration table are stored in an electronic memory accessible by the detector.
4. The method of claim 2 , further comprising determining the channel resistance factor according to a temperature formula associated with the detector.
5. The method of claim 3 , further comprising determining the channel resistance factor associated with the detector at the first temperature at approximately the time of manufacture of the detector.
6. The method of claim 1 , further comprising predetermining a time constant factor of the plurality of pixels in the detector and storing it in an electronic memory accessible by the detector, wherein the time constant factor is associated with a temperature dependency of a time constant of each of the plurality of pixels in the detector, and wherein the step of adjusting comprises adjusting the gain calibration table using the time constant factor.
7. The method of claim 1 , further comprising predetermining an image lag factor of the plurality of pixels in the detector and storing it in an electronic memory accessible by the detector, wherein the image lag factor is associated with a temperature dependency of image lag of each of the plurality of pixels in the detector, and wherein the step of adjusting comprises adjusting the gain calibration table using the image lag factor.
8. A method of operating a digital radiographic detector, the method comprising:
determining a pixel gate voltage associated with the detector at a first temperature;
storing the pixel gate voltage associated with the detector at the first temperature in an electronic table accessible by the detector;
capturing a radiographic image using the detector at a second temperature;
determining a pixel gate voltage associated with the detector at the second temperature; and
reading out the radiographic image data from the detector at the determined pixel gate voltage associated with the detector at the second temperature.
9. The method of claim 8 , further comprising:
capturing a radiographic image using the detector at the first temperature; and
reading out the radiographic image data from the detector at the determined pixel gate voltage associated with the detector at the first temperature.
10. The method of claim 8 , further comprising determining the pixel gate voltage according to a temperature formula associated with the detector.
11. The method of claim 10 , further comprising increasing the pixel gate voltage in response to a decreasing temperature of the detector according to the temperature formula associated with the detector.
12. The method of claim 6 , further comprising using the time constant factor as a common factor for uniformly adjusting the gain calibration table.
13. The method of claim 6 , further comprising determining the time constant factor according to a temperature formula associated with the detector.
14. The method of claim 6 , further comprising determining the time constant factor of the plurality of pixels in the detector at the first temperature at approximately the time of manufacture of the detector.
15. The method of claim 6 , further comprising using the time constant factor as a common factor for uniformly adjusting the gain calibration table.
16. The method of claim 7 , further comprising determining the image lag factor according to a temperature formula associated with the detector.
17. The method of claim 7 , further comprising determining the image lag factor of the plurality of pixels in the detector at the first temperature at approximately the time of manufacture of the detector.
18. The method of claim 7 , further comprising using the image lag factor as a common factor for uniformly adjusting the gain calibration table.