JP2005027913A - X-ray imaging device - Google Patents

Abstract

An object of the present invention is to avoid the inconvenience of irradiating pulsed X-rays before the end of an FPD readout scan, and to ensure the longest possible X-ray pulse width until the next FPD readout scan. .
A frame synchronization signal for starting a reading scan of an FPD 22 and a blanking signal for masking it are sent from an imaging unit 33 to a light receiving unit 32, and a readout signal indicating the status of the reading scan in the light receiving unit 32 is sent to the imaging unit. 33 receives the X-ray irradiation signal to the X-ray controller 34 in response to the fall of the read signal indicating the end of the read scan, and the pulsed X-ray irradiation from the X-ray tube 21 through the X-ray high voltage power source 35. Launch.
[Selection] Figure 1

Description

  The present invention relates to an X-ray imaging apparatus that performs fluoroscopy and imaging with X-rays, and more particularly to an X-ray imaging apparatus that uses an FPD (Flat Panel X-ray Detector) as an X-ray image receiving apparatus.

Conventionally, as an X-ray image receiving apparatus of an X-ray imaging apparatus, it has been usual to use a combination of an image intensifier and a TV camera, but in recent years, as disclosed in Patent Document 1 below, it is small and lightweight. In addition, an FPD capable of a large image receiving surface has been used. In this FPD, many small semiconductor detection elements (corresponding to pixels) that directly generate an electrical signal corresponding to the incident X-ray intensity are arranged in a two-dimensional matrix on a flat panel, and each of these matrix elements is sequentially scanned. Thus, an image signal is obtained by reading the signal. Roughly divided, a type consisting of a conversion film that converts incident X-rays into light and a photoelectric conversion element that converts the light into electrical signals, and a type consisting of X-ray-electrical conversion elements that convert incident X-rays directly into electrical signals There is. In any case, the charges accumulated according to the amount of incident X-rays are read out via the TFT switch, and it is necessary to perform a scan to read the accumulated charges by sequentially turning on the TFT switches for each element. The accumulated charge is cleared when reading is finished.
JP 2001-29337 A

  On the other hand, in the field of X-ray angiography, a technique for obtaining an image by irradiating X-rays in a pulsed manner to reduce the exposure X-ray dose has become mainstream. At that time, in order to improve the image quality, it is necessary to secure the X-ray dose by taking the X-ray irradiation pulse width as large as possible.

  However, in the conventional X-ray imaging apparatus using the FPD, since it is not known whether or not the FPD signal readout scan is completed, various problems arise. First, since it is not known that the FPD signal readout scan has ended, X-ray irradiation cannot be started immediately in accordance with the timing of the end of the readout scan, thus ensuring a sufficient pulse width and improving image quality It is difficult to let In addition, X-ray irradiation may be started before the signal reading scan is completed. In this case, the charge cannot be cleared in time and a correct image signal cannot be obtained. On the contrary, if the signal reading scan is started before the X-ray irradiation is completed, a band-shaped artifact is generated at the signal reading position when the X-ray irradiation is completed.

  According to the present invention, X-ray irradiation control can be performed by grasping the situation of FPD signal readout scanning, whereby the X-ray irradiation pulse width can be increased, and the image quality of the captured X-ray image can be improved. An object of the present invention is to provide an X-ray imaging apparatus improved as possible.

  In order to achieve the above object, in the X-ray imaging apparatus according to the present invention, an X-ray tube that generates X-rays, an FPD disposed opposite to the X-ray tube, and reading data of the FPD are scanned to obtain image data. A high-voltage power supply for applying a high voltage to the X-ray tube, an X-ray controller for controlling the high-voltage power supply so that pulsed X-rays are emitted from the X-ray tube, A reading scan start signal is given to the light receiving unit and a signal indicating a reading state is received from the light receiving unit, and an X-ray irradiation signal is supplied to the X-ray controller in accordance with the signal indicating the reading state, thereby generating a pulsed X-ray. It is characterized in that an imaging unit for starting irradiation is provided.

  The imaging unit controls X-ray irradiation and FPD readout. From now on, X-ray irradiation is started by supplying an X-ray irradiation signal to the X-ray controller, and a readout scan start signal from now is received. This is given to the unit to start reading scan of the light receiving unit. The light receiving unit outputs image data obtained as a result of the readout scan, and also outputs a signal indicating the status of the readout scan, and sends this to the imaging unit. Therefore, two-way communication is performed between the photographing unit and the light receiving unit, and the situation of the readout scan started in response to the readout scan start signal can be grasped on the side of the imaging unit, and the readout scan is completed. An X-ray irradiation signal can be generated at the time point and X-ray irradiation can be started at the end of the readout scan. As a result, it is possible to avoid the occurrence of inconvenience due to the start of X-ray irradiation before the reading scan in the FPD is completed, and it is possible to start X-ray irradiation immediately when the reading scan in the FPD is completed. As long as the longest X-ray pulse width is secured, a high-quality X-ray image can be obtained.

  According to the X-ray imaging apparatus of the present invention, the imaging unit that controls the entire imaging by controlling the timing of the X-ray irradiation and the FPD readout scan, and the light receiving unit that performs the FPD readout scan are bidirectional. It is possible to communicate and reliably capture the end of the FPD readout scan and start up the next pulsed X-ray, thereby avoiding the inconvenience of X-ray irradiation before the end of the FPD readout scan. At the same time, the X-ray pulse width as long as possible can be ensured until the next FPD readout scan is started, and the image quality can be kept good.

  Next, the best mode for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 shows a signal system in an embodiment of the present invention. In FIG. 1, an X-ray tube 21 and an FPD 22 are opposed to each other with a subject 10 interposed therebetween. When a high voltage is applied to the X-ray tube 21 from the X-ray high-voltage power supply 35, X-rays are irradiated from the X-ray tube 21 toward the subject 10, and X-rays transmitted through the subject 10 are emitted. The light is incident on the FPD 22 and charges are accumulated in each detection element of the FPD 22 in accordance with the incident X-ray dose.

  The light receiving unit 32 is a circuit that performs scanning to sequentially read out the accumulated charges of the detection elements of the FPD 22 and outputs image data. This read scan is started in response to a read scan start signal from the photographing unit 33. The output image data is sent to the image monitor device 31 via the imaging unit 33, and an X-ray transmission image of the subject 10 is displayed.

  The X-ray high voltage power supply 35 that applies a high voltage to the X-ray tube 21 is controlled in voltage, pulse width, and the like by an X-ray controller 34. When the X-ray irradiation signal from the imaging unit 33 is given to the X-ray controller 34, the X-ray controller 34 starts up a high-voltage pulse so that a pulsed X-ray rises from the X-ray tube 21. The X-ray high voltage power supply 35 is controlled.

  Therefore, the imaging unit 33 gives an X-ray irradiation signal to the X-ray controller 34 to control the rise timing of the pulsed X-ray, and gives a read scan start signal to the light receiving unit 32 to let the light receiving unit 32 of the FPD 22 By defining the timing of the readout scan, the entire X-ray imaging is controlled.

  Further, the light receiving unit 32 sends a readout signal indicating the state of readout scanning to the photographing unit 33. Further, here, the photographing unit 33 reads out the frame synchronization signal of the image monitor device 31 and sends it as a scan start signal to the light receiving unit 32, and also sends a blanking signal of this frame synchronization signal, and the blanking signal is sent. During this period, the frame synchronization signal is masked so that it does not function as a read scan start signal.

  An X-ray imaging apparatus having such a signal system is configured as, for example, a C-arm X-ray apparatus as shown in FIG. An X-ray tube 21 and an FPD 22 are respectively attached to both ends of the C-type arm 25. The C-type arm 25 is held by a holding device 26, and the holding device 26 is attached to a stand 27. A caster is attached to the stand 27 so as to be movable on the floor of an operating room or the like, but is fixed at a desired position on the floor by a stopper.

  The C-arm 25 can be moved in various directions and positions by the holding device 26 with respect to the stand 27 as indicated by arrows. Thereby, X-ray fluoroscopy and X-ray imaging from all directions and positions can be performed on the subject 10. In the stand 27, the above-described X-ray high voltage power supply 35, a signal system, and the like are stored. The image monitor device 31 is mounted in a housing separate from the stand 27.

  Assume that the frame synchronization signal of the image monitor device 31 is generated, for example, every 1/30 seconds as shown in FIG. When pulsed X-ray irradiation and image data output are performed in accordance with this frame rate, the blanking signal from the imaging unit 33 remains high as shown in FIG. 3B (the blanking signal is output). It is left in a state that is not). At this time, the frame synchronization signal sent to the light receiving unit 32 functions as a readout scan start signal of the FPD 22, and readout scan is started at the timing of the frame synchronization signal.

  The readout signal from the light receiving unit 32 represents the situation of this readout scan, and rises at the start of the readout scan and falls at the end thereof as shown in FIG. Therefore, since the readout signal falls when this readout scan ends, the imaging unit 33 can recognize that the readout scan of the FPD 22 has ended by this fall. Therefore, the imaging unit 33 immediately raises the X-ray irradiation signal at the fall timing, and raises a pulsed X-ray from the X-ray tube 21 through the X-ray controller 34 and the X-ray high voltage power source 35. it can.

  As described above, since the actual end of the readout scan of the FPD 22 can be reliably grasped and a pulsed X-ray can be immediately started up, it is possible to avoid the disadvantage that the X-ray is irradiated before the end of the readout scan. In addition, the X-ray pulse width as long as possible can be ensured until the scanning of the FPD 22 started by the next frame synchronization signal, and the image quality can be kept good.

  FIG. 4 shows a case where pulsed X-ray irradiation and image data output are performed at a rate half that of the frame synchronization signal. In this case, as shown in FIG. Every other signal becomes low, and the frame synchronization signal is masked at a rate of one in two. Only the frame synchronization signal at the timing when the blanking signal is not low and not masked serves as a read scan start signal, and the read scan of the FPD 22 is started by this alternate frame synchronization signal.

  Also at this time, a read signal representing the state of this read scan rises in accordance with the unmasked frame synchronization signal as shown in FIG. This readout signal falls when the readout scan is completed, and since this readout signal is sent from the light receiving unit 32 to the imaging unit 33, the imaging unit 33 catches this fall and immediately raises the X-ray irradiation signal, Pulsed X-rays can be launched from the X-ray tube 21 through the X-ray controller 34 and the X-ray high voltage power source 35.

  Thus, in any case of acquiring an image at any rate, it is possible to avoid the inconvenience of being irradiated with X-rays before the end of the readout scan of the FPD 22, and to the next readout scan of the FPD 22 to be started next. In the meantime, the longest possible X-ray pulse width can be secured, and the image quality can be kept good.

  In addition, the above is related to one example, and the specific configuration is not limited to the above. For example, the C-arm type X-ray apparatus may be a ceiling-mounted type in addition to the floor type as described above, and can also be applied to an X-ray imaging apparatus using an FPD other than the C-arm type X-ray apparatus. .

The block diagram which shows the signal system of embodiment of this invention. The schematic front view which shows the external appearance of the embodiment. The time chart which shows each signal waveform in the embodiment. The time chart which shows the same signal waveform in a different rate.

Explanation of symbols

10 Subject 21 X-ray tube 22 FPD
25 C-type arm 26 Holding device 27 Stand 31 Image monitor device 32 Light receiving unit 33 Imaging unit 34 X-ray controller 35 X-ray high voltage power supply

Claims (1)

  An X-ray tube that generates X-rays, an FPD disposed opposite to the X-ray tube, a light receiving unit that scans and outputs image data of the FPD, and a high voltage that applies a high voltage to the X-ray tube A power source, an X-ray controller that controls the high-voltage power source so that pulsed X-rays are emitted from the X-ray tube, a reading scan start signal is given to the light receiving unit, and a reading status is indicated from the light receiving unit An X-ray imaging apparatus comprising: an imaging unit that receives a signal and applies an X-ray irradiation signal to the X-ray controller in accordance with a signal indicating the readout state to start pulsed X-ray irradiation .

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