Radiation imaging apparatus and radiation imaging system

Patent metadata

Field	Value
Publication number	US-9541653-B2
Application number	US-201414189281-A
Country	US
Kind code	B2
Filing date	Feb 25, 2014
Priority date	Feb 28, 2013
Publication date	Jan 10, 2017
Grant date	Jan 10, 2017

Abstract

A radiation imaging apparatus includes a pixel array in which a plurality of pixels which detects radiation are arrayed to form a plurality of rows and a plurality of columns, a detection circuit which detects information having correlation to a radiation dose to the pixel array and output a detection signal corresponding to the information, and a control unit which detects radiation irradiation to the pixel array based on a plurality of integrated values obtained by integrating one of the detection signal and a result of processing applied to the detection signal in a plurality of integral intervals and control the pixel array in accordance with the detection.

First claim

What is claimed is:

1. A radiation imaging apparatus comprising:
a pixel array in which a plurality of pixels configured to detect radiation are arrayed to form a plurality of rows and a plurality of columns;
a detection circuit configured to detect information representative of a radiation dose to the pixel array and output a detection signal corresponding to the information; and
a control unit configured to perform radiation detection processing until radiation irradiation of the pixel array is detected and to control the pixel array in accordance with the detection, wherein in the radiation detection processing, the control unit integrates either the detection signal or a result of processing applied to the detection signal, in a plurality of integral intervals which are different from each other, and detects the radiation irradiation of the pixel array based on comparison between a threshold value and an integrated value obtained by the integration.

2. The apparatus according to claim 1 , wherein each of the plurality of pixels includes a converter configured to generate and accumulate charges corresponding to the radiation dose, and
the detection circuit outputs, as the detection signal, a signal corresponding to a current flowing to a bias line that gives a bias potential to the converter.

3. The apparatus according to claim 2 , wherein the control unit controls the pixel array so as to repeat an initialization operation of sequentially initializing the plurality of pixels of the pixel array in units of at least one row, until radiation irradiation is detected.

4. The apparatus according to claim 3 , wherein each of the plurality of pixels further includes a switch element configured to connect the converter to a signal line, and is configured to output a signal corresponding to the charges accumulated in the converter to the signal line,
wherein the initialization operation includes an operation of setting the switch element of each pixel of a row to be initialized in a conductive state, and
the processing includes obtaining a difference between the detection signal when the switch element is in the conductive state and the detection signal when the switch element is in a nonconductive state.

5. The apparatus according to claim 4 , wherein the processing further includes obtaining a difference between the latest difference and the preceding difference for the same row.

6. The apparatus according to claim 3 , wherein the processing includes obtaining a difference between the latest detection signal and the preceding detection signal for the same row.

7. The apparatus according to claim 1 , wherein the control unit detects radiation irradiation of the pixel array based on a difference between at least two integrated values out of a plurality of integrated values obtained by integrations in the plurality of integral intervals.

8. The apparatus according to claim 7 , wherein the control unit detects radiation irradiation of the pixel array based on a difference between at least two integrated values obtained by integrations.

9. The apparatus according to claim 1 , wherein the control unit detects radiation irradiation of the pixel array based on comparison between the threshold value and a plurality of integrated values obtained by integrations in the plurality of integral intervals.

10. The apparatus according to claim 9 , wherein the control unit detects radiation irradiation of the pixel array when one of the plurality of integrated values exceeds the corresponding threshold value.

11. The apparatus according to claim 9 , wherein the control unit outputs information representing the integral interval associated with the integrated value that exceeds the corresponding threshold value out of the plurality of integrated values.

12. The apparatus according to claim 1 , wherein the control unit performs integration for the plurality of integral intervals using a single integrator.

13. The apparatus according to claim 1 , wherein the control unit performs integration for the plurality of integral intervals using a plurality of integrators.

14. The apparatus according to claim 1 , wherein start times of the plurality of integral intervals are different from each other, and in each of the plurality of integral intervals, start time of an integral interval is earlier than end time of the integral interval.

15. A radiation imaging apparatus comprising:
a pixel array in which a plurality of pixels configured to detect radiation are arrayed to form a plurality of rows and a plurality of columns;
a detection circuit configured to detect information representative of a radiation dose to the pixel array and output a detection signal corresponding to the information; and
a control unit configured to detect radiation irradiation of the pixel array based on a plurality of integrated values obtained by integrating either the detection signal or a result of processing applied to the detection signal, in a plurality of integral intervals and to control the pixel array in accordance with the detection,
wherein the control unit detects radiation irradiation of the pixel array based on comparison between a threshold value and the plurality of integrated values, and
wherein a unique threshold value is assigned to each of the plurality of integral intervals.

16. A radiation imaging apparatus comprising:
a pixel array in which a plurality of pixels configured to detect radiation are arrayed to form a plurality of rows and a plurality of columns;
a detection circuit configured to detect information representative of a radiation dose to the pixel array and output a detection signal corresponding to the information; and
a control unit configured to detect radiation irradiation of the pixel array based on a plurality of integrated values obtained by integrating either the detection signal or a result of processing applied to the detection signal, in a plurality of integral intervals and to control the pixel array in accordance with the detection,
wherein the control unit detects radiation irradiation of the pixel array based on comparison between a threshold value and the plurality of integrated values, and
wherein the control unit detects radiation irradiation of the pixel array when a predetermined number of integrated values including at least two of the plurality of integrated values exceed the corresponding threshold values.

17. A radiation imaging apparatus comprising:
a pixel array in which a plurality of pixels configured to detect radiation are arrayed to form a plurality of rows and a plurality of columns;
a detection circuit configured to detect information representative of a radiation dose to the pixel array and output a detection signal corresponding to the information; and
a control unit configured to detect radiation irradiation of the pixel array based on a plurality of integrated values obtained by integrating either the detection signal or a result of processing applied to the detection signal, in a plurality of integral intervals and to control the pixel array in accordance with the detection,
wherein the control unit detects radiation irradiation of the pixel array based on comparison between a threshold value and the plurality of integrated values, and
wherein letting W be a length of one integral interval out of the plurality of integral intervals, and T be the threshold value assigned to the one integral interval, the length of another integral interval out of the plurality of integral intervals is k×W (k is a real number larger than 1), and the threshold value as

Assignees

• Canon Kk

Inventors

• Iwashita Atsushi
• Kameshima Toshio
• Yagi Tomoyuki
• Takenaka Katsuro
• Okada Hideyuki
• Sato Sho
• Sato Eriko
• Ryu Takuya

Classifications

• H04N25/617

  for reducing electromagnetic interference, e.g. clocking noise · CPC title

• H04N25/75

  Circuitry for providing, modifying or processing image signals from the pixel array · CPC title

• H04N25/616 Primary

  involving a correlated sampling function, e.g. correlated double sampling [CDS] or triple sampling · CPC title

• H04N23/30

  for generating image signals from X-rays · CPC title

• A61B6/4208 Primary

  characterised by using a particular type of detector · CPC title