Radiographic image detecting device and control method thereof

• US 8,879,689 B2
• Filed: 12/02/2013
• Issued: 11/04/2014
• Est. Priority Date: 07/26/2011
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: Ohta, Yasunori, Nishino, Naoyuki, Nakatsugawa, Haruyasu, Iwakiri, Naoto, Kitano, Kouichi
• Primary Examiner(s): SONG, HOON K
• Application Number:
  US14/094,234
• Publication Number:
  US 20140086391A1
• Time in Patent Office: 337 Days
• Field of Search: 378/97, 378/108, 378/110, 378/112
• US Class Current: 378/97
• CPC Class Codes: A61B 6/4233 using matrix detectors
• CPC Class Codes: A61B 6/4283 characterised by a detector unit being housed in a cassette
• CPC Class Codes: A61B 6/542 involving control of exposure
• CPC Class Codes: H04N 23/71 Circuitry for evaluating the brightness variation
• CPC Class Codes: H04N 25/53 Control of the integration time
• CPC Class Codes: H04N 25/76 Addressed sensors, e.g. MOS or CMOS sensors
• CPC Class Codes: H04N 5/32 Transforming X-rays cameras or camera modules for generating image signals from X-rays H04N23/30; circuitry of SSIS for transforming X-rays into image signals H04N25/30

Abstract

An X-ray image detecting device has an FPD having a matrix of pixels each for accumulating signal charge in accordance with an X-ray irradiation amount. An imaging area of the FPD is partitioned into a plurality of divided sections A to I. Each of the divided sections A to I has a short pixel for detecting X-ray irradiation. In a synchronization control for controlling the FPD in synchronization with detection of a start of X-ray emission from an X-ray source, a control unit for controlling the X-ray image detecting device uses all the divided sections A to I. In an automatic exposure control for stopping the X-ray emission from the X-ray source by detecting a total X-ray irradiation amount, the control unit uses part of the divided sections, e.g. the short pixels of the divided sections that are judged to be opposed to an object in the synchronization control.

Claims

1. A radiographic image detecting device comprising:

an image detector having an imaging area having a matrix of a plurality of pixels each for accumulating signal charge in accordance with an irradiation amount of radiation emitted from a radiation source, for detecting a radiographic image by receiving said radiation passed through an object;

a plurality of radiation detectors disposed in said imaging area, each for outputting a detection signal in accordance with said irradiation amount of said radiation; and

a control unit for performing a synchronization control for synchronizing an operation of said image detector with emission start timing of said radiation based on said detection signal of said radiation detector, and an automatic exposure control for controlling a total irradiation amount of said radiation based on said detection signal of said radiation detector, wherein

said detection signal of said radiation detector disposed in a first detection area in said imaging area is used in said synchronization control, and said detection signal of said radiation detector disposed in a second detection area smaller than said first detection area is used in said automatic exposure control.

2. The radiographic image detecting device according to claim 1, wherein said second detection area is included in said first detection area.

3. The radiographic image detecting device according to claim 2, wherein said control unit designates said second detection area based on said detection signals outputted from said plurality of radiation detectors disposed in said first detection area.

4. The radiographic image detecting device according to claim 3, wherein said control unit designates said second detection area by using said detection signal read in said synchronization control.

5. The radiographic image detecting device according to claim 3, said control unit compares said detection signals outputted from said plurality of radiation detectors disposed in said first detection area, and judges a section having said radiation detector that outputs a relatively low detection signal as a section opposed to said object, and designates said section opposed to said object as said second detection area.

6. The radiographic image detecting device according to claim 1, wherein said imaging area is composed of a plurality of divided sections each having said radiation detector, and said first detection area is composed of a combination of said divided sections, and said second detection area is composed of another combination of said divided sections.

7. The radiographic image detecting device according to claim 6, wherein each of said divided sections has a same number of radiation detectors.

8. The radiographic image detecting device according to claim 1, wherein in said synchronization control, said control unit monitors a start of emission of said radiation from said radiation source based on said detection signal of said radiation detector disposed in said first detection area, and makes said image detector start accumulating said signal charge upon detecting said start of emission of said radiation from said radiation source.

9. The radiographic image detecting device according to claim 8, wherein in said synchronization control, said control unit detects said start of emission, when one of said detection signals of said plurality of radiation detectors disposed in said first detection area has exceeded a threshold value.

10. The radiographic image detecting device according to claim 1, wherein in said automatic exposure control, said control unit measures a total irradiation amount of said radiation by integrating said detection signal of said radiation detector, and makes said radiation source stop emitting said radiation when said total irradiation amount has reached a threshold value.

11. The radiographic image detecting device according to claim 1, wherein when said total irradiation amount of said radiation has reached a threshold value, said control unit ends accumulation of said signal charge by said image detector.

12. The radiographic image detecting device according to claim 1, wherein in said automatic exposure control, said control unit measures a total irradiation amount of said radiation by integrating said detection signal of said radiation detector, and controls a gain in reading said signal charge from said pixel based on said total irradiation amount.

13. The radiographic image detecting device according to claim 1, wherein said radiation detector is a short pixel in which said pixel and a signal line for reading said signal charge from said pixel are always short out, and said short pixel always outputs to said signal line said signal charge in accordance with said irradiation amount of said radiation.

14. The radiographic image detecting device according to claim 1, wherein said radiation detector is a photosensor array stacked on said image detector, and said photosensor array has a plurality of detection elements for outputting said detection signal in accordance with said irradiation amount of said radiation.

15. The radiographic image detecting device according to claim 14, wherein said photosensor array is made of an organic photoelectric conversion material.

16. The radiographic image detecting device according to claim 15, wherein said photosensor array is disposed on a side of said radiation source with respect to said imaging area.

17. The radiographic image detecting device according to claim 1 allows taking a moving image, in addition to a still image.

18. The radiographic image detecting device according to claim 1, wherein

said radiation source continuously emits a plurality of radiation pulses;

and

said control unit performs said synchronization control and said automatic exposure control on a pulse-by-pulse basis.

19. A control method of a radiographic image detecting device having an imaging area having a matrix of a plurality of pixels each for accumulating signal charge in accordance with an irradiation amount of radiation emitted from a radiation source, said radiographic image detecting device detecting a radiographic image by receiving said radiation passed through an object, said control method comprising the steps of:

performing a synchronization control for synchronizing an operation of said radiographic image detecting device with emission start timing of said radiation based on a detection signal of a radiation detector disposed in a first detection area of said imaging area; and

performing an automatic exposure control for controlling a total irradiation amount of said radiation based on said detection signal of said radiation detector disposed in a second detection area smaller than said first detection area.