JP4840124B2 - Radiography equipment - Google Patents

Description

  The present invention relates to a radiation imaging apparatus, and more particularly to a radiation imaging apparatus including a plurality of imaging systems.

This type of conventional apparatus will be described by taking an X-ray imaging apparatus as an example.
Conventionally, as an X-ray detector of an X-ray imaging apparatus, it has been common to use a combination of an image intensifier and a TV camera, but in recent years, a flat panel capable of being small and light and having a large image receiving surface. A type X-ray detector (hereinafter referred to as FPD) has been used (see, for example, Patent Document 1).

On the other hand, as an X-ray imaging apparatus, a technique for obtaining an image by outputting X-rays in pulses 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 the read scan end timing is roughly determined from the read time of one frame, X-ray irradiation can be started immediately according to the read scan end timing. Therefore, there is a problem that it is difficult to improve the image quality by securing a sufficient pulse width. In addition, X-ray irradiation may be started before the signal reading scan is completed. In this case, the charge is not cleared in time, and a band-shaped artifact is generated. On the contrary, even if the readout scan is started before the X-ray irradiation is finished, a band-shaped artifact is generated at the signal readout position when the X-ray irradiation is finished. Therefore, X-ray irradiation control is performed by grasping the situation of the signal reading scan of the FPD so that the X-ray irradiation pulse width can be increased, and the image quality of the photographed X-ray image can be improved. An improved imaging method has been established (for example, see Patent Document 2).
JP 2001-29337 A JP 2005-27913 A (page 3, right column, line 34-page 4, left column, line 6, line 3)

However, the conventional example having such a configuration has the following problems.
In an X-ray imaging apparatus having a plurality of imaging systems having an X-ray tube and an X-ray detector, since the control is performed for each imaging system, the readout status of each imaging system is unknown. As a result, for example, when the signal readout time varies depending on the field-of-view size and image roughness, if the X-ray irradiation is continuously performed alternately, the signal readout time is short with the conventional method. Scattered rays due to X-ray irradiation in the imaging system will be applied to signal readout of other imaging systems, and that portion will appear in the image as a band-shaped artifact.

  The present invention has been made in view of such circumstances, and in a radiation imaging apparatus having a plurality of imaging systems, there is a problem in that scattered radiation of one imaging system is applied to readout of the other imaging system. An object is to provide a radiation imaging apparatus that can be avoided.

The present invention adopts the following configuration in order to achieve such an object.
That is, a first aspect of the present invention, a radiation imaging apparatus having a plurality of imaging systems having a radiation detector for detecting radiation irradiated with radiation irradiator for irradiating radiation from the radiation irradiator, the photographing The system has different readout times depending on the conditions for reading imaging data from the radiation detector, and the readout of signals related to readout in the imaging system with the longest readout time among the plurality of imaging systems with different readout times is completed. Immediately after the readout in the imaging system is completed in accordance with the timing , an imaging control means is provided for controlling radiation to be emitted from a radiation irradiator of the imaging system as a target in the plurality of imaging systems. Features.

[Action / Effect]
According to the first aspect of the present invention, an imaging system having a radiation irradiator and a radiation detector has different readout times depending on conditions for reading imaging data from the radiation detector. Immediately after the readout in the imaging system is completed in accordance with the readout end timing of the signal related to readout in the imaging system having the longest readout time among the plurality of imaging systems having different readout times , the imaging control means Control is performed so that radiation is emitted from the radiation irradiator of the imaging system as the object .

Thus, the radiation imaging apparatus having a plurality of the imaging system, if the read time for each of the imaging system from the radiation detector in accordance with the conditions of reading the imaging data is different, imaging scattered radiation of one of the imaging system is other hand In addition to avoiding the inconvenience associated with the readout of the system, it is possible to ensure the longest possible pulse width of radiation until the next readout scan and maintain good image quality .

According to the radiographic apparatus according to the present invention, in the radiographic apparatus having a plurality of imaging systems, when the readout time of each imaging system differs according to the conditions for reading the imaging data from the radiation detector, In addition to avoiding the inconvenience of the scattered radiation of the system on the readout of the other imaging system, the longest possible radiation pulse width can be ensured until the next readout scan to improve the image quality. Can keep.

  Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating the overall configuration of the first embodiment. FIG. 2 is a timing chart of imaging control in an X-ray imaging apparatus having a plurality of conventional imaging systems. FIG. 3 is a timing chart of shooting control according to the first embodiment. FIG. 4 is a diagram illustrating a shooting control logic circuit according to the first embodiment.

  The overall configuration of the first embodiment will be described with reference to FIG. In addition, the imaging system combining the components indicated by A in the drawing is called an imaging system A, and the imaging system combining the components indicated by B in the drawing is called an imaging system B.

  The X-ray imaging apparatus according to the first embodiment is used as a biplane X-ray imaging apparatus mainly in the field of angiography. This biplane X-ray imaging apparatus includes two imaging systems. One imaging system A continuously and alternately images the subject from a predetermined direction of the subject and the other imaging system B from another predetermined direction of the subject. The imaging system A includes an X-ray tube 2A that irradiates X-rays, an FPD 3A that is disposed opposite to the top plate 1, a read control unit 4A that performs a read scan of the FPD 3A, and an X-ray irradiation start command. And an X-ray irradiation control unit 6A for driving 2A. As with the imaging system A, the imaging system B includes an FPD 3B, a readout control unit 4B, and an X-ray irradiation control unit 6B. The imaging system A and the imaging system B share the top plate 1 on which the subject P is placed, and the imaging control unit 5 that causes the readout control unit 4A and the readout control unit 4B to start readout scanning.

  In the FPD 3A, a large number of 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. An image signal is obtained by sequentially scanning each element on the matrix and reading the signal. The FPD 3A reads charges accumulated according to the amount of incident X-rays via a TFT switch, and performs scanning to read accumulated charges by sequentially turning on the TFT switches for each element. The accumulated charge is cleared when reading is finished. The same applies to the FPD 3B.

  The read control unit 4A is a circuit that performs a scan for sequentially reading the accumulated charge of each detection element of the FPD 3A, and outputs a read signal 40A indicating the read status. This readout scan is started in response to a frame synchronization signal F from the imaging control unit 5. The read image data is sent to an image output unit (not shown) via the imaging control unit 5, and an X-ray imaging image of the subject P is displayed. The same applies to the read control unit 4B. Note that the read signal 40A and the read signal 40B in the first embodiment correspond to signals related to reading in the present invention.

  When the readout signal 40A is input from the readout control unit 4A, the imaging control unit 5 gives an imaging start signal 50A to the X-ray irradiation control unit 6A. Further, a frame synchronization signal F is given to the read control unit 4A to control the timing of read scan to the FPD 3A. As described above, the imaging control unit 5 controls the entire X-ray imaging apparatus. The photographing control unit 5 performs similar control for the photographing system B.

  When the imaging start signal 50A is input from the imaging control unit 5, the X-ray irradiation control unit 6A activates the X-ray irradiation signal 60A and controls the irradiation timing of pulsed X-rays from the X-ray tube 2A. The same applies to the X-ray irradiation control unit 6B. Note that the imaging start signals 50A and 50B and the X-ray irradiation signals 60A and 60B in Example 1 correspond to the signals related to radiation irradiation of the present invention.

  A method of taking the timing of imaging control in an X-ray imaging apparatus having a plurality of conventional imaging systems will be described with reference to the timing chart of FIG. Since the entire configuration of the conventional X-ray imaging apparatus is assumed to be the same as that of the X-ray imaging apparatus of the first embodiment, the same reference numerals as those in FIG. 1 are used.

  At timing T1, the imaging control unit 5 raises the X-ray irradiation signal 60A simultaneously with the fall of the readout signal 40A from the readout control unit 4A. The X-ray irradiation signal 60A can output X-rays having an arbitrary pulse width until the next frame synchronization signal F. At timing T2, the read control unit 4A raises the read signal 40A when receiving the frame synchronization signal F. When the image reading from the FPD 3A is completed, the imaging control unit 5 causes the read signal 40A to fall. At timing T3, the readout control unit 4B performs empty readout from the FPD 3B in order to clear the scattered component of the X-rays emitted from the X-ray tube 2A. When the idle reading is completed, the imaging control unit 5 causes the idle readout signal 40B to fall. At timing T4, the imaging control unit 5 outputs an X-ray irradiation signal 60B simultaneously with the fall of the readout signal 40B. At this time, since the readout signal 40A is still in the output state, the readout controller 4A is affected by the scattered X-rays from the X-ray tube 2B (shaded portion 7 in the figure).

  A method of timing of imaging control in the X-ray imaging apparatus including a plurality of imaging systems according to the first embodiment will be described with reference to the timing chart of FIG.

Until timing T1, the imaging control unit 5 waits until it detects the fall of the readout signals from both readout control units 4A and 4B. When the fall of both readout signals is detected, the X-ray irradiation signal 60A is raised. The X-ray irradiation control unit 6A can output X-rays having an arbitrary pulse width until the next frame synchronization signal F. At timing T2, the read control unit 4A raises the read signal 40A when receiving the frame synchronization signal F. When the image reading from the FPD 3A is completed, the imaging control unit 5 causes the read signal 40A to fall. At timing T3, the readout control unit 4B performs empty readout from the FPD 3B in order to clear the scattered component of the X-rays emitted from the X-ray tube 2A. When the idle reading is completed, the imaging control unit 5 causes the idle readout signal 40B to fall. Until timing T4, the imaging control unit 5 waits until it detects the falling edge of the readout signal from both the readout control units 4A and 4B. Upon detecting the falling edge of both of the read signal, it raises the X-ray irradiation signal 60 B. The X-ray irradiation control unit 6B can output X-rays having an arbitrary pulse width until the next frame synchronization signal F. At this time, since the output of the readout signal 40A has already stopped, the readout control unit 4A is not affected by the scattered X-rays from the X-ray tube 2B. At timing T5, the read control unit 4B raises the read signal 40B when receiving the frame synchronization signal F. When the reading of the image from the FPD 3B is completed, the imaging control unit 5 causes the reading signal 40B to fall. At timing T6, the readout control unit 4A performs empty readout from the FPD 3A in order to clear the scattered radiation component of the X-rays emitted from the X-ray irradiation control unit 6B. When empty reading is completed, the imaging control unit 5 causes the read signal 40A for empty reading to fall. Thereafter, this procedure is repeated.

  Timing control in the imaging control unit 5 of the biplane X-ray imaging apparatus according to the first embodiment will be described with reference to the logic circuit of FIG.

  The timing control circuit in the photographing control unit includes an AND circuit 8, a flip-flop circuit (FF circuit) 9, an AND circuit 10A, and an AND circuit 10B.

  The read signal 40A and the read signal 40B output from the read control unit 4A and the read control unit 4B are inverted in signal level and input to the AND circuit 8. That is, the AND circuit 8 outputs High only when both the read signal 40A and the read signal 40B are at the low level. As a result, when the fall of both readout signals is detected at the timing T1 in FIG. 3, the imaging start signal 50A can be output to the X-ray irradiation controller 6A. The signal output from the AND circuit 8 is a read end signal indicating that the fall of the read signal 40A and the read signal 40B has been detected. Next, the frame synchronization signal F is input to the FF circuit 9. The output level of the FF output signal 70 output from the FF circuit 9 is alternately High and Low. When this output level is High, it is input to the AND circuit 10A together with the read end signal. The imaging start signal 50A output from the AND circuit 10A is input to the X-ray irradiation control unit 6A and output as the X-ray irradiation signal 60A to drive the X-ray tube 2A. When this output level is Low, it is converted to High before being input to the AND circuit 10B, and is input to the AND circuit 10B together with the read end signal. The imaging start signal 50B output from the AND circuit 10B is input to the X-ray irradiation control unit 6B and output as the X-ray irradiation signal 60B to drive the X-ray tube 2B. Thereby, X-rays can be irradiated alternately from the X-ray tubes 2A and 2B.

  According to the present embodiment, the imaging control unit 5 can control the X-ray irradiation signal of the imaging system as a target in both imaging systems in accordance with the readout signals of the imaging system A and the imaging system B. This avoids inconvenience that scattered X-rays of one imaging system are applied to readout of the other imaging system, and ensures the longest possible X-ray pulse width until the next readout scan. Image quality can be kept good.

According to the present embodiment, the imaging control unit 5 matches the readout signal 40A having the longest time in the imaging system A and the imaging system B with the X-ray irradiation signal of the imaging system that is the target in both imaging systems. 60 B can be controlled. Therefore, even when the readout time of the imaging system A is longer than the readout time of the imaging system B , it is possible to avoid the inconvenience that the scattered X-rays of the imaging system B are applied to the readout of the imaging system A and to start next. The X-ray pulse width as long as possible can be ensured until the readout scan is completed, and the image quality can be kept good.

  The present invention is not limited to the above-described embodiment, and can be modified as follows.

  (1) In the above-described first embodiment, X-rays are taken as an example, but the present invention may be radiation other than X-rays.

  (2) In the above-described first embodiment, two imaging systems have been described, but three or more imaging systems may be used.

  (3) In the above-described first embodiment, the X-ray imaging apparatus according to the first embodiment is mainly used as a biplane X-ray imaging apparatus in the field of angiography. However, the X-ray imaging apparatus used in other fields is also used. I do not care.

  (4) In the first embodiment described above, the FPD 3A and the FPD 3B are arranged at right angles, but the arrangement angle is not particularly limited, such as being arranged obliquely to each other.

1 is a block diagram illustrating an overall configuration of Example 1. FIG. It is a timing chart of the imaging control in the X-ray imaging apparatus provided with the conventional some imaging system. 3 is a timing chart of shooting control according to the first exemplary embodiment. FIG. 3 is a logic circuit diagram of shooting control according to the first embodiment.

Explanation of symbols

P ... Subject 1 ... Top plate 2A, 2B ... X-ray tube 3A, 3B ... FPD
4A, 4B ... Read control unit 5 ... Imaging control unit 6A, 6B ... X-ray irradiation control unit 7 ... Influence of scattered X-rays 8 ... AND circuit 9 ... Flip-flop circuit (FF circuit)
10A, 10B ... AND circuit of imaging system A, AND circuit of imaging system B 40A, 40B ... Read signal 50A, 50B ... Imaging start signal 60A, 60B ... X-ray irradiation signal 70 ... Flip-flop output signal (FF output signal)

Claims (1)

In a radiation imaging apparatus including a plurality of imaging systems having a radiation irradiator that irradiates radiation and a radiation detector that detects radiation emitted from the radiation irradiator , the imaging system reads imaging data from the radiation detector. a is read time differs depending on the conditions, read in the imaging system in accordance with the read end timing of signals related to reading in the longest imaging system read time in the read time is different imaging systems ends Immediately after, a radiography apparatus comprising radiography control means for controlling radiation to be emitted from a radiation irradiator of an imaging system as a target among the plurality of imaging systems.

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