JP2018175658A - X-ray diagnosis apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-definition image of an area of interest in a wide visual field while reducing an exposure dose to a subject.SOLUTION: An X-ray diagnosis apparatus of the present embodiment includes an X-ray detector, a filter, and a control part. The X-ray detector includes: a scintillator which converts the X-ray irradiated by an X-ray tube into light; and first and second light detectors which share the scintillator and detect the light converted by the scintillator to output an electric signal. The filter has an opening to attenuate the X-ray irradiated by the X-ray tube. The control part displays, on the display part, the image in which a first image generated by the electric signal output by the first light detector and a second image generated by the electric signal output by the second light detector are combined.SELECTED DRAWING: Figure 1

Description

  Embodiments of the present invention relate to an X-ray diagnostic apparatus.

  Conventionally, in an examination using an X-ray diagnostic apparatus, a narrow region of interest may be observed at high resolution. Thus, the first detector having a large field of view employing a thin film transistor (TFT) array and the pixel pitch smaller than the first detector using a complementary metal oxide semiconductor (CMOS) can be obtained. There is known an X-ray diagnostic apparatus provided with a detector having a fine second detector.

  In such an X-ray diagnostic apparatus, the first detector and the second detector are switched and used according to the application, and a first image generated from the X-ray signal output by the first detector There is a technique for displaying either one of the second image generated from the X-ray signal output by the second detector.

US Patent Application Publication No. 2015/0003584

  The problem to be solved by the present invention is to provide an X-ray diagnostic apparatus capable of reducing an exposure dose of a subject and acquiring a high definition image of a region of interest with a wide field of view.

  The X-ray diagnostic apparatus of the embodiment includes an X-ray detector, a filter, and a control unit. The X-ray detector shares the scintillator with a scintillator that converts X-rays emitted from the X-ray tube into light, and detects the light converted by the scintillator and outputs an electrical signal. And a second light detector. The filter has an opening and attenuates the X-rays emitted from the X-ray tube. The control unit combines a first image generated from the electrical signal output by the first light detector and a second image generated from the electrical signal output by the second light detector. The displayed image is displayed on the display unit.

FIG. 1 is a block diagram showing a configuration example of the X-ray diagnostic apparatus according to the first embodiment. FIG. 2 is a block diagram showing a configuration example of the X-ray detector according to the first embodiment. FIG. 3 is a diagram for explaining a first method according to the prior art. FIG. 4 is a diagram for explaining a second method according to the prior art. FIG. 5 is a diagram for explaining the first embodiment. FIG. 6 is a block diagram showing a configuration example of the X-ray image acquisition apparatus according to the first embodiment. FIG. 7A is a diagram for explaining the first embodiment. FIG. 7B is a diagram for describing the first embodiment. FIG. 8 is a flowchart showing the processing procedure of the X-ray image acquisition apparatus according to the first embodiment. FIG. 9 is a view for explaining a modification of the first embodiment. FIG. 10 is a block diagram showing a configuration example of the X-ray image acquisition apparatus according to the second embodiment. FIG. 11 is a diagram for explaining the second embodiment. FIG. 12 is a flowchart showing the processing procedure of the X-ray image acquisition apparatus according to the second embodiment.

  Hereinafter, an X-ray diagnostic apparatus according to an embodiment will be described with reference to the drawings. The embodiment is not limited to the following embodiment. In addition, the contents described in one embodiment apply in principle to the other embodiments as well.

First Embodiment
FIG. 1 is a block diagram showing a configuration example of the X-ray diagnostic apparatus 100 according to the first embodiment. As shown in FIG. 1, the X-ray diagnostic apparatus 100 according to the first embodiment includes a catheter bed 101, a holding device 102, an X-ray high voltage generator 107, a holding device control device 108, and a monitor 109. , An X-ray image acquisition device 110, an X-ray detector (Flat Panel Detector) controller 120, and an input interface 130.

  The catheter bed 101 is movable in the vertical direction and the horizontal direction, and the subject P is placed thereon. The holding device 102 is rotatable in the arrow R direction around the Z axis, and holds the X-ray source 103 and the X-ray detector 106 in an opposite manner.

  The X-ray source 103 includes an X-ray tube 103a for emitting X-rays, and a diaphragm and radiation quality adjustment filter 103b (also referred to as a collimator) used for the purpose of reducing the exposure dose to the object P and improving the image quality of image data. Have. An ROI (Region Of Interest) attenuator 104 attenuates the X-ray emitted from the X-ray source 103. The ROI attenuator 104 has an aperture. That is, the ROI attenuator 104 has an opening and attenuates the X-ray emitted from the X-ray source 103.

  The X-ray detector (FPD: also referred to as Flat Panel Detector) 106 detects X-rays transmitted from the X-ray source 103 and transmitted through the subject P. The X-ray detector 106 according to the first embodiment will be described with reference to FIG. FIG. 2 is a block diagram showing a configuration example of the X-ray detector 106 according to the first embodiment.

  For example, as illustrated in FIG. 2, the X-ray detector 106 includes a first light detector 106 a, a second light detector 106 b, and a scintillator 106 c. The first photodetector 106a and the scintillator 106c constitute a first detector 106d (also referred to as a first FPD), and the second photodetector 106b and the scintillator 106c constitute a second detector 106e (first 2) is also configured.

  The scintillator 106 c converts the X-rays emitted from the X-ray source 103 into light. The first photodetector 106a includes a two-dimensional image sensor employing, for example, a thin film transistor (TFT) array formed of amorphous silicon, detects light converted by the scintillator 106c, and outputs an electrical signal. Do. The second photodetector 106 b includes a two-dimensional image sensor employing, for example, a complementary metal oxide semiconductor (CMOS) transistor, detects light converted by the scintillator 106 c, and outputs an electrical signal. The electric signal output by the first light detector 106a and the second light detector 106b is also referred to as an X-ray signal.

  Thus, the scintillator 106c is shared by the first light detector 106a and the second light detector 106b. In other words, the X-ray detector 106 shares the scintillator 106c with the scintillator 106c that converts the X-ray emitted from the X-ray source 103 into light, detects the light converted by the scintillator 106c, and outputs an electrical signal And a second light detector 106b. Then, the first light detector 106a and the second light detector 106b respectively output electric signals obtained by simultaneously detecting the light converted by the scintillator 106c.

  Further, as shown in FIG. 2, the first light detector 106 a and the second light detector 106 b have a plurality of element portions which are constituent units of pixels. Each of the element units converts a fluorescent image obtained by X-ray incidence into an electrical signal and stores the signal in a photodiode (PD: Photo Diode). In the example of FIG. 2, the case where the first photodetector 106a has eight element portions and the second photodetector 106b has eight element portions is illustrated.

  Here, the pixel pitch of each element unit of the second light detector 106 b is smaller than the pixel pitch of each element unit of the first light detector 106 a. In the example shown in FIG. 2, the pixel pitch of each element portion of the first light detector 106a corresponds to the pixel pitch of two element portions of the second light detector 106b. That is, the second photodetector 106b has a higher resolution than the first photodetector 106a. Also, as shown in FIG. 2, the first photodetector 106a has a wider field of view size than the second photodetector 106b.

  Furthermore, in the second photodetector 106b employing CMOS, the maximum incident X-ray dose tends to be smaller compared to the first photodetector 106a employing amorphous silicon. For this reason, in the second photodetector 106b, when it is intended to irradiate a high dose of X-rays and collect X-ray image data having a high S / N (Signal to Noise) ratio, the S / N ratio is high. It may not be possible to obtain x-ray image data.

  In addition, the second photodetector 106 b has less residual components of the electrical signal than the first photodetector 106 a. In the first photodetector 106a, the generated charge is trapped in the internal trap level in the photodiode. On the other hand, in the second photodetector 106b, the characteristic of the CMOS is that there are few traps of charge generated in the photodiode.

  Return to FIG. The X-ray detector controller 120 controls the timing of reading of the electrical signal by the X-ray detector 106. In addition, the X-ray detector controller 120 acquires an electrical signal from the X-ray detector 106, generates image data from the acquired electrical signal, and outputs the image data to the X-ray image acquisition device 110. Here, the X-ray detector control device 120 collects the electrical signal output by the first FPD, and generates a first image data (also referred to as a first FPD image or a first image) from the collected electrical signal. Are generated and output to the X-ray image acquisition device 110. The X-ray detector control device 120 also collects the electrical signal output by the second FPD, and generates second image data (also referred to as a second FPD image or a second image) from the collected electrical signal. It is generated and output to the X-ray image acquisition device 110.

  The X-ray image acquisition device 110 controls the holding device control device 108 and the X-ray high voltage generator 107, collects the image data output by the X-ray detector control device 120, and performs image processing. Here, the X-ray image acquisition device 110 acquires image data from the first FPD and the second FPD at substantially the same timing. The details of the X-ray image acquisition device 110 will be described later.

  The X-ray high voltage generator 107 supplies a high voltage to the X-ray tube 103a. The holding device control device 108 controls the rotation and the like of the holding device 102 under the control of the X-ray image acquisition device 110. The monitor 109 displays an X-ray image or the like generated by the X-ray image acquisition device 110. The monitor 109 may be configured of a plurality of sub monitors, or may be a large screen monitor capable of arbitrarily dividing the display area according to an instruction of the operator. Further, when the monitor 109 has a plurality of sub-monitors, the display area of each sub-monitor may be arbitrarily divided according to the instruction of the operator. The input interface 130 is a keyboard, a control panel, a foot switch or the like, and receives input of various operations on the X-ray diagnostic apparatus 100 from the operator.

  The overall configuration of the X-ray diagnostic apparatus 100 according to the first embodiment has been described above. In such a configuration, the X-ray diagnostic apparatus 100 according to the first embodiment collects the X-ray signal output by the X-ray detector 106. Then, the X-ray diagnostic apparatus 100 causes the monitor 109 to display an image generated from the acquired X-ray signal. For example, the X-ray diagnostic apparatus 100 causes the monitor 109 to display an image set by the operator according to the clinical site. For example, the X-ray diagnostic apparatus 100 switches the first image and the second image according to the instruction of the operator and causes the monitor 109 to display the image.

  By the way, in the prior art, when performing ROI fluoroscopy to obtain a high-definition image of a region of interest with a wide field of view using the high-definition second FPD and the ROI attenuator 104, two main processes are performed. It was considered to apply the method. FIG. 3 is a diagram for explaining a first method according to the prior art, and FIG. 4 is a diagram for explaining a second method according to the prior art.

  The upper view of FIG. 3 shows an X-ray diagnostic apparatus having a first FPD and a second FPD independently. For example, as shown in the upper part of FIG. 3, in the first method according to the prior art, the first FPD having a wide field of view and normal resolution allows the first X-ray signal in the presence of the ROI attenuator 104 to Switching between acquisition and acquisition of a second x-ray signal in the absence of the ROI attenuator 104 by a second FPD with high resolution while having a narrow field of view. In the first method according to the prior art, as shown in the lower part of FIG. 3, the first image generated from the first X-ray signal in the presence of the ROI attenuator 104 and the first image in the absence of the ROI attenuator 104. An ROI Fluoro image is generated that is combined with a second image generated from the two X-ray signals.

  The upper part of FIG. 4 shows the case of using a single third FPD with high definition and wide field of view. For example, as shown in the upper part of FIG. 4, the second method according to the prior art collects a third X-ray signal in the presence of the ROI attenuator 104 by a third FPD having a wide field of view and high resolution. . Then, in the second method according to the prior art, as shown in the lower part of FIG. 4, an ROI Fluoro image including an area in the presence of the ROI attenuator 104 and an area in the absence of the ROI attenuator 104 is generated.

  However, in the first method according to the prior art, either one of the first image and the second image needs to use a past image. That is, since the first image and the second image must be separated in time and collected, it can not be said that acquisition of a high definition image can be realized with a wide view and a central (ROI) portion. Furthermore, in the first method according to the prior art, since the same subject is photographed at least twice, the exposure dose of the subject is increased. Moreover, in the second method according to the prior art, it is necessary to create a third FPD that achieves high definition within a wide field of view. However, creating the third FPD is not realistic in cost and is difficult to realize. Further, the region where the ROI attenuator 104 is disposed has a small amount of original X-ray incidence. For this reason, the influence of the quantization error at the time of A / D conversion and the fall of the S / N ratio accompanying the reduction of X-ray incident amount is included.

  Therefore, when performing ROI fluoroscopy, the X-ray diagnostic apparatus 100 according to the first embodiment reduces the exposure dose of the subject by the method shown in FIG. Get a nice image. FIG. 5 is a diagram for explaining the first embodiment. For example, the X-ray diagnostic apparatus 100 according to the first embodiment combines the first FPD, the second FPD, and the ROI attenuator 104 with one scintillator layer interposed as shown in the upper diagram of FIG. 5. To use. Here, the first FPD and the second FPD output electric signals obtained by simultaneously detecting the light converted by the scintillator 106 c. Then, the X-ray diagnostic apparatus 100 according to the first embodiment causes the monitor 109 to display an ROI Fluoro image as shown in the lower part of FIG. More specifically, the X-ray diagnostic apparatus 100 according to the first embodiment uses the first image generated from the electrical signal output by the first photodetector 106a and the second image detector 106b. An image combining the second image generated from the output electrical signal is displayed on the monitor 109. Such ROI fluoroscopic imaging is performed by the X-ray image acquisition device 110. Hereinafter, the details of the ROI fluoroscopic copying by the X-ray image acquisition device 110 will be described using FIG. The X-ray image acquisition device 110 is an example of a control unit.

  FIG. 6 is a block diagram showing a configuration example of the X-ray image acquisition device 110 according to the first embodiment. In FIG. 6, for convenience of explanation, the X-ray source 103, the ROI attenuator 104, the X-ray detector 106, the X-ray detector control device 120, the monitor 109, and the input interface 130 are also illustrated. In the example shown in FIG. 2, the X-ray detector 106 is described to have the first photodetector 106a, the second photodetector 106b, and the scintillator 106c. As shown in FIG. 1, it has a video signal amplifier circuit and an A / D (Analog to Digital) conversion circuit. Further, in the second photodetector 106b, the amplifier circuit of the first stage is disposed in each element portion, and an amplified signal is output, so that an electric signal with reduced noise can be output. In addition, an A / D conversion circuit may be configured, and in such a case, the second photodetector 106 b converts the accumulated electric signal into a digital signal and then outputs the digital signal. In this case, further noise reduction is possible. As shown in FIG. 6, in the X-ray detector 106, the first FPD is provided closer to the X-ray source 103 than the second FPD.

  The X-ray detector 106 further includes a drive control circuit 106 f and a video signal processing circuit 106 g. The drive control circuit 106 f controls the drive timing of the first light detector 106 a and the second light detector 106 b under the control of the X-ray detector control device 120. The video signal processing circuit 106g collects the electrical signal output from the first light detector 106a, outputs it to the X-ray detector control device 120, and outputs the electrical signal output from the second light detector 106b. It is collected and output to the X-ray detector controller 120.

  Further, in the example shown in FIG. 6, transmission of images from the X-ray detector control device 120 to the X-ray image acquisition device 110 is provided with data lines for the first image and for the second image, respectively. Although the parallel system is described, the embodiment is not limited thereto. For example, transmission of an image from the X-ray detector control device 120 to the X-ray image acquisition device 110 may be a serial method in which data lines are shared between the first image and the second image.

  As shown in FIG. 6, the X-ray image acquisition device 110 according to the first embodiment includes an FPD control circuit 201, an image processing circuit 202, a disk 203, a disk 204, a resize circuit 205, and a combining circuit 206. , A UI control circuit 207, a coefficient storage circuit 208, and a multiplication circuit 209.

  The FPD control circuit 201 controls the timing of reading of the electrical signal by the X-ray detector 106 via the X-ray detector control device 120. The image processing circuit 202 performs image processing on the image data output by the X-ray detector control device 120. The disk 203 stores X-ray images. For example, the disk 203 is a hard disk drive (HDD) and stores a second image. The disk 204 stores an x-ray image. For example, the disk 204 is an HDD and stores the first image. In the example shown in FIG. 6, the case where the X-ray image acquisition apparatus 110 includes the disk 203 for the second image and the disk 204 for the first image will be described. And the second image may share one disk.

  The input interface 130 receives an instruction from the operator, and passes the received instruction to the UI control circuit 207. The input interface 130 also receives an instruction from the operator to control the ROI attenuator 104. For example, the input interface 130 is set so that the aperture of the ROI attenuator 104 and the field of view of the second detector overlap.

  The UI control circuit 207 causes the image processing circuit 202 to display an image for which an instruction has been received from the operator via the input interface 130. For example, when the display of the first image is received, the UI control circuit 207 turns the switch A to the a side. Thus, the image processing circuit 202 causes the monitor 109 to display the first image. Further, for example, when the UI control circuit 207 receives the display of the second image, the UI control circuit 207 turns the switch A to the b side. Thus, the image processing circuit 202 causes the monitor 109 to display the second image.

  The UI control circuit 207 also receives an instruction to perform ROI fluoroscopic copying from the operator via the input interface 130, and passes the received instruction to the FPD control circuit 201. Then, the FPD control circuit 201 causes the X-ray detector control device 120 to select a drive mode in which the video signal amplification coefficient necessary for each of the first FPD and the second FPD is set. Thereby, the first FPD and the second FPD are driven according to the set drive mode.

  Here, in the ROI Fluoro image shown in the lower part of FIG. 5, the image portion of the first FPD in which the ROI attenuator 104 is inserted has a small incident X-ray dose and a small input signal. For this reason, in order to prevent the influence of the quantization error due to A / D conversion from being mixed into the collected image, the first FPD video signal amplifier circuit sets a high analog gain according to the small X dose (“ It is called "gain change processing". For example, when displaying the ROI Fluoro image, the FPD control circuit 201 changes the gain value of the first light detector 106 a as compared with the case where the ROI Fluoro image is not displayed. In other words, when applying gain change processing, the FPD control circuit 201 sets the gain value of the first light detector 106 a in the presence of the ROI attenuator 104 higher than the gain value in the absence of the ROI attenuator 104. Do. More specifically, the FPD control circuit 201 sets the gain value of the first light detector 106 a in the presence of the ROI attenuator 104 higher than the gain value in the absence of the ROI attenuator 104. As a result, the analog gain set in the first FPD is 1 / (X-ray attenuation ratio by the ROI attenuator 104) times that in non-ROI fluoroscopic copying.

The FPD control circuit 201 may cause the X-ray detector control device 120 to select a drive mode in which pixels are added as a drive mode of the first FPD, instead of the gain change process. In such a case, the X-ray detector control device 120 performs pixel addition on the signal detected by the first light detector 106 a (referred to as “pixel addition processing”). For example, when applying the pixel addition process, the X-ray detector control device 120 generates a first image from the electrical signal output by the first FPD, and generates each first pixel of the generated first image. By theoretically treating a plurality of adjacent pixels as one pixel, sensitivity is theoretically increased. As an example, the sensitivity becomes 2 ^twice by pixel addition the surrounding four pixels, sensitivity is 2 ³ times by adding the surrounding 8 pixels. As described above, since the X-ray detector controller 120 raises the sensitivity by increasing the output image level to the power, it is possible to improve the S / N ratio. In such a case, the analog gain is 1 / {(X-ray attenuation ratio by the ROI attenuator 104) × (power-multiplied value)} times as compared with the non-ROI fluoroscopic copying in non-pixel addition driving.

  In addition, the UI control circuit 207 receives an instruction to execute ROI fluoroscopic copying from the operator via the input interface 130, and causes the image processing circuit 202 to display an ROI Fluoro image. When the image processing circuit 202 receives an instruction to display the ROI Fluoro image, the image processing circuit 202 outputs the first image generated from the electric signal output from the first light detector 106 a and the second image generated by the second detector 106 b. An image obtained by combining the second image generated from the electrical signal is displayed on the monitor 109.

  Here, when displaying the ROI Fluoro image, the image processing circuit 202 may display the first image and the second image independently, or the second image is superimposed on the first image. You may 7A and 7B are diagrams for explaining the first embodiment.

  FIG. 7A shows the case where the first image and the second image are displayed independently. In the example shown in FIG. 7A, the monitor 109 has a plurality of sub monitors 109a and sub monitors 109b. As shown in FIG. 7A, the first image is displayed on the sub monitor 109a, and the second image is displayed on the sub monitor 109b. In such a case, the UI control circuit 207 switches the switch A shown in FIG. 6 between the a side and the b side. Thereby, the image processing circuit 202 causes the sub monitor 109a to display the first image when the switch A falls to the a side, and the second image to the sub monitor 109 b when the switch A falls to the b side. Display.

  FIG. 7B shows the case where the second image is superimposed on the first image. Similar to the example shown in FIG. 7A, in the example shown in FIG. 7B, the monitor 109 includes a plurality of sub monitors 109a and 109b. As shown in FIG. 7B, the sub monitor 109a displays a composite image obtained by combining the first image and the second image. In this case, no image is displayed on the sub monitor 109b.

  Here, when displaying a composite image, the image processing circuit 202 causes the combining circuit 206 to execute image combining processing described below. Here, prior to image combining processing, gain changing processing or pixel addition processing is executed as preprocessing.

  For example, in order to allow the user to easily recognize the part where the ROI attenuator 104 is arranged and the part where the ROI attenuator 104 is not arranged on the monitor 109, the first image part in the composite image is dare The coefficient stored in the coefficient storage circuit 208 may be read out and the first image may be multiplied by the multiplication circuit 209. In such a case, the coefficient α stored by the coefficient storage circuit 208 is a value less than one. The multiplication circuit 209 passes the first image after multiplication by the coefficient to the synthesis circuit 206.

  Subsequently, pre-processing on the second image will be described. For example, when display of the composite image is selected, the resize circuit 205 corrects the difference between the pixel pitch of the first image and the pixel pitch of the second image before combining with the first image. In other words, the resize circuit 205 corrects the pixel pitch of the second image. More specifically, the resizing circuit 205 reduces the second image to match the pixel pitch of the first image. The resize circuit 205 delivers the corrected second image to the synthesis circuit 206. Then, the combining circuit 206 generates a combined image using the first image after the pre-processing and the second image after the pre-processing. In other words, the combining circuit 206 superimposes and displays the second image on the first image. For example, the combining circuit 206 aligns and combines the first image multiplied by the coefficient by the multiplying circuit 209 and the second image after resizing processing by the resizing circuit 205. In other words, the synthesis circuit 206 superimposes the second image whose pixel pitch has been corrected on the first image. Note that the resizing process may be applied to the first image according to the resolution of the monitor to be used, in which case resizing to correct the difference from the pixel pitch of the resized first image is Applied to the image of 2.

  The UI control circuit 207 turns the switch A shown in FIG. 6 to the c side. As a result, the composite image is displayed on the monitor 109. That is, the image processing circuit 202 causes the monitor 109 to display an image in which the first image outside the region of interest and the second image inside the region of interest are combined. In addition, even when the density of the first image and the density of the second image become identical by the gain change processing or the pixel addition processing, the synthesis circuit 206 notifies the position of the ROI attenuator 104, so that the ROI Only the frame of the attenuator 104 may be superimposed on the composite image.

  FIG. 8 is a flowchart showing the processing procedure of the X-ray image acquisition device 110 according to the first embodiment. FIG. 8 shows a flowchart for explaining the overall operation of the X-ray image acquisition apparatus 110, and describes which step of the flowchart corresponds to each component.

  Step S101 is a step implemented by the input interface 130. In step S101, the input interface 130 receives the selection of ROI fluoroscopic copying. Step S102 is a step implemented by the input interface 130. In step S102, the input interface 130 sets the ROI to the second detector.

  Step S103 is a step implemented by the FPD control circuit 201. In step S103, the FPD control circuit 201 sets the analog gain of the first signal higher than the gain value in the absence of the ROI attenuator 104. Step S104 is a step implemented by the image processing circuit 202. In step S104, the image processing circuit 202 causes the monitor 109 to display an image obtained by combining the first image and the second image. For example, the image processing circuit 202 may display the first image and the second image independently, or may display the second image superimposed on the first image.

  In the example illustrated in FIG. 8, although the gain change processing is performed in step S103, the embodiment is not limited to this. For example, in step S103, pixel addition processing may be executed instead of gain change processing. Furthermore, in step S103, both gain change processing and pixel addition processing may be performed.

  As described above, in the first embodiment, the X-ray image acquisition device 110 includes the first image generated from the electrical signal output by the first light detector 106a and the second light detector 106b. An image combining the second image generated from the output electrical signal is displayed on the monitor 109. For example, the X-ray image acquisition device 110 causes the monitor 109 to display an image obtained by combining the first image outside the region of interest and the second image inside the region of interest. Thereby, according to the first embodiment, it is possible to acquire a high definition image of the region of interest with a wide field of view. Furthermore, in the first embodiment, the first image and the second image are acquired simultaneously. This makes it possible to avoid multiple X-ray irradiations on the subject. As a result, according to the first embodiment, it is possible to reduce the X-ray exposure to the subject or to reduce the burden on the subject's examination. Further, according to the first embodiment, the operator does not have to perform image acquisition a plurality of times, which makes it possible to make the examination more efficient.

  In the first embodiment, the gain value of the first light detector 106 a in the presence of the ROI attenuator 104 is set higher than the gain value in the absence of the ROI attenuator 104. Thereby, according to the first embodiment, it is possible to suppress a decrease in image visibility of the region in which the ROI attenuator 104 is disposed.

  Further, in the first embodiment described above, the X-ray image acquisition apparatus 110 is described as performing processing in the procedure shown in FIG. 8, but the embodiment is not limited to this. For example, the X-ray image acquisition device 110 may omit step S104.

  Further, although the X-ray image acquisition apparatus 110 is described as having the coefficient storage circuit 208 and the multiplication circuit 209 in the above-described embodiment, the embodiment is not limited to this. For example, the X-ray image acquisition device 110 may be configured without the coefficient storage circuit 208 and the multiplication circuit 209.

(Modification of the first embodiment)
In the example shown in FIG. 7B, the case of displaying the composite image on one of the two sub-monitors of the monitor 109 has been described. By the way, when displaying a synthetic | combination image, it is desirable to display a region of interest by the high resolution intrinsic | native to 2nd FPD. FIG. 9 is a view for explaining a modification of the first embodiment. For example, as shown in FIG. 9, when the monitor 109 is a large screen monitor capable of arbitrarily dividing the display area according to an instruction of the operator, the composite image is displayed without dividing the display area. May be

Second Embodiment
In the first embodiment, the case where the image quality of the portion in which the ROI attenuator 104 is disposed is improved by changing the gain setting of the first FPD has been described. In the second embodiment, without changing the gain setting of the first FPD as in the first embodiment, the S / N ratio is obtained by averaging a plurality of frames of the first image instead of using normal driving. The case of improving the While the region of the first image is not the region of interest, the image has a poor S / N ratio due to the small amount of the original X-ray signal. Therefore, it is intended to compensate for the decrease in S / N ratio by this frame addition instead of reducing the time resolution by frame addition. The overall configuration of the X-ray diagnostic apparatus 100 according to the second embodiment is the same as the X-ray image acquisition apparatus 110a except that it has a different function from the X-ray image acquisition apparatus 110 according to the first embodiment. The configuration is the same as the configuration example 1 and thus the description is omitted here. The X-ray image acquisition device 110a is an example of a control unit.

  FIG. 10 is a block diagram showing a configuration example of the X-ray image acquisition device 110a according to the second embodiment. In FIG. 10, the X-ray source 103, the ROI attenuator 104, the X-ray detector 106, the X-ray detector control device 120, the monitor 109, and the input interface 130 are also illustrated for convenience of explanation. As shown in FIG. 10, in the X-ray detector 106, the first FPD is provided closer to the X-ray source 103 than the second FPD.

  Further, in the example shown in FIG. 10, transmission of an image from the X-ray detector controller 120 to the X-ray image acquisition device 110a uses a common data line for the first image and the second image. Although it is described that the serial system is used, the embodiment is not limited thereto. For example, transmission of images from the X-ray detector control device 120 to the X-ray image acquisition device 110 may be a parallel method using dedicated data lines for the first image and the second image.

  As shown in FIG. 10, the X-ray image acquisition device 110a according to the second embodiment includes an FPD control circuit 201, an image processing circuit 202a, a disk 203, a disk 204, a resize circuit 205, and a combining circuit 206. , A UI control circuit 207a, a coefficient storage circuit 208, and a multiplication circuit 209. In addition, in each part shown in FIG. 10, when it has the same function as each part shown in FIG. 6, the same code | symbol is provided and detailed description is abbreviate | omitted. Further, in the example shown in FIG. 10, the case where the X-ray image acquisition device 110a includes the disk 203 for the second image and the disk 204 for the first image will be described. And the second image may share one disk.

  The input interface 130 receives an instruction from the operator, and passes the received instruction to the UI control circuit 207a. The input interface 130 also receives an instruction from the operator to control the ROI attenuator 104. For example, the input interface 130 is set so that the aperture of the ROI attenuator 104 and the field of view of the second detector overlap. The UI control circuit 207a causes the image processing circuit 202a to display an image for which an instruction has been received from the operator via the input interface 130. For example, when the UI control circuit 207a receives the display of the first image, the UI control circuit 207a turns the switch A to the a side. Thus, the image processing circuit 202a causes the monitor 109 to display the first image. Further, for example, when the UI control circuit 207a receives the display of the second image, the UI control circuit 207a turns the switch A to the b side. Thus, the image processing circuit 202a causes the monitor 109 to display the second image.

  Further, the UI control circuit 207a receives an instruction to perform ROI fluoroscopic copying from the operator via the input interface 130, and causes the image processing circuit 202a to display an ROI Fluoro image. The image processing circuit 202 a includes a frame addition circuit 210. For example, the frame addition circuit 210 averages the first images of a plurality of frames in the presence of the ROI attenuator 104. The frame addition circuit 210 according to the second embodiment will be described with reference to FIG.

  FIG. 11 is a diagram for explaining the second embodiment. FIG. 11 shows the timing of read drive of the first FPD and the timing of read drive of the second FPD when an instruction to perform ROI fluoroscopic copying is received.

  The upper diagram of FIG. 11 shows the timing of read drive of the first FPD. As shown in the upper drawing of FIG. 11, in the case where X-rays are irradiated in a pulse shape to acquire an X-ray image, the first photodetector 106a is a storage period in which generated charges are accumulated during X-ray pulse irradiation. And a readout period for reading out the charge signal during non-irradiation of the X-ray pulse.

  For example, after the storage period, the first photodetector 106 a outputs an X-ray signal by reading out the charge signal in the lead-out period. Then, the X-ray detector controller 120 generates a first image using the acquired X-ray signal. The X-ray detector control device 120 outputs the generated first image to the frame addition circuit 210 each time the first image is generated.

  Here, when displaying the ROI Fluoro image, the X-ray detector control device 120 changes the drive rate as compared with the case where the ROI Fluoro image is not displayed. In other words, when applying the averaging process, the X-ray detector control device 120 further changes the drive rate with respect to the first light detector 106a. For example, when applying averaging processing every two frames, the refresh rate on the monitor 109 is 1⁄2. Here, when the refresh rate on the display on the monitor 109 is not desired to be 1⁄2, the X-ray detector control device 120 sets the driving rate of the first light detector 106 a to double.

  Note that the region of the first image covered by the ROI attenuator 104 is not a region of interest in the first place. If the refresh rate may be halved, the X-ray detector controller 120 does not necessarily have to change the drive rate of the first light detector 106a. In addition, when adding two frames, if two frames are added each time one frame is generated, an afterimage due to the influence of the previous frame is generated, but the refresh rate is never halved. Therefore, even in such a case, the X-ray detector control device 120 may not change the drive rate of the first light detector 106a.

  In addition, the X-ray detector control apparatus 120 may combine the pixel addition processing described in the first embodiment with the second embodiment. For example, the X-ray detector control device 120 may perform pixel addition on the signal detected by the first light detector 106a, and further frame averaging processing of the first image. Alternatively, the X-ray detector control apparatus 120 may combine the gain change processing described in the first embodiment with the second embodiment. For example, the X-ray detector controller 120 sets the gain value of the first light detector 106a in the presence of the ROI attenuator 104 higher than the gain value in the absence of the ROI attenuator 104, and further, the first image Frame averaging processing. Alternatively, the X-ray detector control apparatus 120 may combine the gain changing process and the frame averaging process described in the first embodiment with the second embodiment. That is, when the ROI attenuator 104 is inserted, the X-ray detector control device 120 performs gain change processing for changing the gain value with respect to the first light detector 106a, and the first image for a plurality of frames. At least one of an averaging process of averaging and a pixel addition process of pixel summing of the signal detected by the first light detector 106 a is applied.

Then, the frame addition circuit 210 obtains the first image output by the X-ray detector control device 120 and performs averaging. Here, the frame addition circuit 210 is a recursive filter, and as shown in the upper diagram of FIG. 11, the latest image of the acquired first images is multiplied by a predetermined coefficient k, and the latest first The past image acquired one before the image is multiplied by (1-k) and added. That is, when the latest first image is P _n and the past image is Q _{n -1} , the generated image Q _n is expressed by the following equation. That is, “Q _n = k × P _n + (1−k) × Q _n−1 ”. Here, by using a desired coefficient for the coefficient k, the effect can be set arbitrarily.

  Then, the frame addition circuit 210 is multiplied by the coefficient corresponding to the X-ray attenuation ratio by the ROI attenuator 104 after the averaging processing. This makes it possible to keep the image level uniform where the ROI attenuator 104 is placed and where the ROI attenuator 104 is not placed.

  On the other hand, the lower part of FIG. 11 shows the timing of read drive of the second FPD. As shown in the lower part of FIG. 11, the second light detector 106b outputs an X-ray signal by reading out the charge signal in the lead-out period after the storage period. Then, the X-ray detector controller 120 generates a second image using the acquired X-ray signal. The X-ray detector control device 120 outputs the generated second image to the image processing circuit 202a each time the second image is generated.

  When displaying the ROI Fluoro image, the image processing circuit 202a may display the first image and the second image independently, or may display the second image superimposed on the first image. Good. When the second image is superimposed on the first image, the image processing circuit 202a causes the combining circuit 206 to execute the same image combining process as that of the first embodiment. Here, as in the first embodiment, prior to the image combining process, preprocessing is performed on the first image and the second image. For example, the combining circuit 206 corrects the pixel pitch of the second image, and superimposes and displays the second image on the first image. Then, the image processing circuit 202a causes the monitor 109 to display an image in which the first image outside the region of interest and the second image inside the region of interest are combined.

  FIG. 12 is a flowchart showing the processing procedure of the X-ray image acquisition device 110 a according to the second embodiment. FIG. 12 shows a flowchart for explaining the overall operation of the X-ray image acquisition device 110a, and explains which step of the flowchart each component corresponds to.

  Step S201 is a step implemented by the input interface 130. In step S201, the input interface 130 receives the selection of ROI fluoroscopic copying. Step S202 is a step implemented by the input interface 130. In step S202, the input interface 130 sets the ROI to the second detector.

  Step S203 is a step implemented by the X-ray detector control device 120. In step S203, the X-ray detector control device 120 performs pixel addition on the first signal. Step S204 is a step implemented by the frame addition circuit 210. In step S204, the frame addition circuit 210 performs frame addition on the first image. Step S205 is a step implemented by the image processing circuit 202a. In step S205, the image processing circuit 202a causes the monitor 109 to display an image obtained by combining the first image and the second image. For example, the image processing circuit 202a may display the first image and the second image independently, or may display the second image superimposed on the first image.

  As described above, in the second embodiment, the X-ray image acquisition device 110 includes the first image generated from the electrical signal output by the first light detector 106a and the second light detector 106b. An image combining the second image generated from the output electrical signal is displayed on the monitor 109. For example, the X-ray image acquisition device 110 causes the monitor 109 to display an image obtained by combining the first image outside the region of interest and the second image inside the region of interest. Thereby, according to the second embodiment, it is possible to acquire a high definition image of the region of interest with a wide field of view. Furthermore, in the second embodiment, the first image and the second image are acquired simultaneously. This makes it possible to avoid multiple X-ray irradiations on the subject. As a result, according to the second embodiment, it is possible to reduce the X-ray exposure to the subject or to reduce the burden on the subject's examination. Further, according to the second embodiment, the operator does not have to perform image acquisition a plurality of times, so it is possible to make the examination more efficient.

  In the second embodiment, in the presence of the ROI attenuator 104, the first images of a plurality of frames are averaged. Thereby, according to the second embodiment, it is possible to suppress the deterioration of the image quality of the region in which the ROI attenuator 104 is disposed.

  Further, in the first embodiment described above, the X-ray image acquisition device 110a has been described as performing processing in the procedure shown in FIG. 12, but the embodiment is not limited to this. For example, the X-ray image acquisition device 110a may omit step S203.

  In the above-described embodiment, the X-ray image acquisition device 110a is described as having the coefficient storage circuit 208 and the multiplication circuit 209, but the embodiment is not limited to this. For example, the X-ray image acquisition device 110 a may be configured without the coefficient storage circuit 208 and the multiplication circuit 209.

(Other embodiments)
Embodiments are not limited to the above-described embodiments.

  In the embodiment described above, although the ROI attenuator 104 is controlled by the input interface 130, the embodiment is not limited to this. For example, the UI control circuit 207 of the X-ray image acquisition device 110 or the UI control circuit 207 a of the X-ray image acquisition device 110 a may control the ROI attenuator 104 via the input interface 130.

  In the embodiment described above, as shown in FIG. 6 and FIG. 10, etc., in the X-ray detector 106, the first FPD is described as being provided closer to the X-ray source 103 than the second FPD. Embodiments are not limited to this. For example, in the X-ray detector 106, the second FPD may be provided closer to the X-ray source 103 than the first FPD.

  Also, in the above-described embodiment, the case of displaying the first image and the second image independently and the case of displaying the composite image obtained by combining the first image and the second image have been described. The embodiment is not limited to this. For example, the first image, the second image, and the composite image may be displayed independently. Alternatively, any two images of the first image, the second image, and the composite image may be displayed independently.

  Moreover, although the X-ray-image acquisition device 110 (110a) was demonstrated as what has each circuit in embodiment mentioned above, embodiment is not limited to this. For example, the X-ray image acquisition device 110 (110a) is a processor, and by reading and executing a program stored in a storage circuit, the X-ray image acquisition device 110 shown in FIG. 6 or the X-ray image shown in FIG. The same function as that of the collection device 110a may be performed. In such a case, each processing function executed by the processor is stored in the storage circuit in the form of a program executable by a computer. The processor implements each function corresponding to each program by reading each program from the storage circuit and executing the program. In other words, the processor in the state where each program is read has the same functions as the circuits shown in the X-ray image acquisition device 110 shown in FIG. 6 and the X-ray image acquisition device 110 a shown in FIG. It becomes.

  The word “processor” used in the above description is, for example, a central processing unit (CPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), a programmable logic device (for example, It means circuits such as Simple Programmable Logic Device (SPLD), Complex Programmable Logic Device (CPLD), and Field Programmable Gate Array (FPGA). The processor implements a function by reading and executing a program stored in a memory circuit. Note that instead of storing the program in the memory circuit, the program may be directly incorporated in the circuit of the processor. In this case, the processor implements the function by reading and executing a program embedded in the circuit. Each processor according to the present embodiment is not limited to being configured as a single circuit for each processor, and may be configured as one processor by combining a plurality of independent circuits to realize the function. Good. Furthermore, a plurality of components in FIG. 6 and FIG. 10 may be integrated into one processor to realize its function.

  In the above description of the embodiment, each component of each illustrated device is functionally conceptual and does not necessarily have to be physically configured as illustrated. That is, the specific form of the dispersion and integration of each device is not limited to that shown in the drawings, and all or a part thereof is functionally or physically dispersed in any unit depending on various loads, usage conditions, etc. It can be integrated and configured. Furthermore, all or any part of each processing function performed in each device may be realized by a CPU and a program analyzed and executed by the CPU, or may be realized as wired logic hardware.

  Further, the control method described in the above embodiment can be realized by executing a control program prepared in advance by a computer such as a personal computer or a workstation. This control program can be distributed via a network such as the Internet. The control program can also be recorded on a computer-readable recording medium such as a hard disk, a flexible disk (FD), a CD-ROM, an MO, and a DVD, and can be executed by being read from the recording medium by a computer.

  According to at least one embodiment described above, it is possible to reduce the radiation dose of the subject and obtain a wide view and a high definition image of the region of interest.

  While certain embodiments of the present invention have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the invention. These embodiments can be implemented in other various forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the invention described in the claims and the equivalents thereof as well as included in the scope and the gist of the invention.

100 X-ray diagnostic apparatus 104 ROI attenuator 106 X-ray detector 110 X-ray image acquisition apparatus

Claims (12)

A scintillator that converts X-rays emitted from an X-ray tube into light, and a first light detector and a second light that share the scintillator and detect the light converted by the scintillator and output an electrical signal An X-ray detector having a detector;
A filter having an opening and attenuating X-rays emitted from the X-ray tube;
Display an image combining a first image generated from the electrical signal output by the first light detector and a second image generated from the electrical signal output by the second light detector A control unit to be displayed on the unit;
X-ray diagnostic device equipped with   The X-ray diagnostic apparatus according to claim 1, wherein the first light detector and the second light detector respectively output electric signals obtained by simultaneously detecting the light converted by the scintillator. The first light detector has a wider field of view size than the second light detector,
The X-ray diagnosis according to claim 1 or 2, wherein the control unit causes the display unit to display an image in which the first image outside the region of interest and the second image inside the region of interest are combined. apparatus.   The control unit, when the filter is inserted, performs gain change processing for changing a gain value with respect to the first light detector, and addition averaging processing for adding and averaging the first images of a plurality of frames. The X-ray diagnostic apparatus according to any one of claims 1 to 3, wherein at least one of pixel addition processing for pixel addition of the signal detected by the first light detector is applied.   The control unit may set the gain value of the first light detector in the presence of the filter to be higher than the gain value in the absence of the filter when applying the gain change processing. X-ray diagnostic apparatus as described in.   The X-ray diagnostic apparatus according to claim 4, wherein the control unit further changes a drive rate with respect to the first light detector when applying the averaging process.   The X-ray diagnosis according to claim 4, wherein the control unit virtually treats a plurality of adjacent pixels as one pixel in each pixel of the first image when applying the pixel addition process. apparatus.   The X-ray diagnostic apparatus according to any one of claims 1 to 7, wherein the control unit displays the first image and the second image independently.   The X-ray diagnostic apparatus according to any one of claims 1 to 7, wherein the control unit causes the second image to be superimposed and displayed on the first image. The second light detector has a resolution higher than that of the first light detector,
The X-ray diagnostic apparatus according to claim 9, wherein the control unit corrects a pixel pitch of the second image and causes the second image to be superimposed and displayed on the first image.   The X-ray diagnostic apparatus according to any one of claims 1 to 10, wherein the control unit further displays an area in which the filter is disposed.   The X-ray diagnostic apparatus according to any one of claims 1 to 11, wherein the control unit sets the opening of the filter and the field of view of the second light detector to overlap.

Images