X-ray diagnostic equipment, medical image processing equipment and program

Abstract

To generate a three-dimensional image with a high degree of precision.SOLUTION: An X-ray diagnostic device includes an X-ray detector, an acquisition unit, and a processing unit. The X-ray detector includes a scintillator for converting an X-ray emitted from an X-ray tube to light, and a first light detector for outputting a detection signal according to the light to which the X-ray is converted by the scintillator and a second light detector with a field of vision smaller than that of the first light detector, which share the scintillator. The acquisition unit acquires first image data collected sequentially on the basis of the detection signal output by the first light detector, and second image data collected sequentially on the basis of the detection signal output from the second light detector when the X-ray detector is rotated around a subject by an arm supporting the X-ray detector. The processing unit compensates for the second image data by using out-of-field-of-vision region information, which is the information on an image region other than the region of the second image data in the first image data, for each rotation angle of the X-ray detector.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The embodiments disclosed in this specification and the drawings relate to an X-ray diagnostic apparatus, a medical image processing apparatus, and a program. [Background technology]

[0002] For example, in the treatment of cerebral aneurysm using an X-ray diagnostic apparatus, an X-ray image depicting a wide area of ​​the subject is observed, and a site of interest is observed in a high-resolution X-ray image. As an X-ray diagnostic apparatus used in such a case, for example, an X-ray diagnostic apparatus equipped with an X-ray detector including a first detector with a large field of view and a second detector with a smaller field of view and higher resolution than the first detector is known. By using an X-ray detector including the first detector and the second detector, such an X-ray diagnostic apparatus can simultaneously collect X-rays that have passed through the subject with each detector, and collect two X-ray images with different field of view sizes and resolutions.

[0003] In addition, the X-ray diagnostic apparatus can also reconstruct three-dimensional image data using multiple image data collected by rotational imaging. Here, when reconstruction is performed using only a portion of the area included in the image data, artifacts may occur at the edge of the reconstructed three-dimensional image data. In order to reduce such artifacts, a technique is known for X-ray diagnostic apparatuses in which, when reconstructing a portion of the area included in the image data, the data surrounding the portion of the area is also reconstructed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-200573 A Summary of the Invention [Problem to be solved by the invention]

[0005] The problem to be solved by the embodiments disclosed in this specification and the drawings is to enable accurate generation of a three-dimensional image. However, the problem to be solved by the embodiments disclosed in this specification and the drawings is not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described later can also be positioned as other problems. [Means for solving the problem]

[0006] The X-ray diagnostic apparatus according to the embodiment includes an X-ray detector, an acquisition unit, and a processing unit. The X-ray detector includes a scintillator that converts X-rays irradiated from an X-ray tube into light, a first photodetector that shares the scintillator and outputs a detection signal according to the light converted by the scintillator, and a second photodetector that has a smaller field of view than the first photodetector. The acquisition unit rotates the X-ray detector around the subject using an arm that supports the X-ray detector, and acquires first image data sequentially collected based on the detection signal output by the first photodetector and second image data sequentially collected based on the detection signal output by the second photodetector. The processing unit supplements the second image data for each rotation angle of the X-ray detector using outside-field-of-view area information that is information on an image area other than the area of ​​the second image data in the first image data. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a block diagram showing an example of the configuration of an X-ray diagnostic apparatus according to the first embodiment. [Diagram 2] FIG. 2 is a diagram showing an example of the configuration of the X-ray detector according to the first embodiment. [Diagram 3] FIG. 3 is a diagram for explaining an artifact according to the first embodiment. [Figure 4] FIG. 4 is a diagram showing an example of an outside-of-field area according to the first embodiment. [Diagram 5] FIG. 5 is a flowchart showing a procedure of processing in the X-ray diagnostic apparatus according to the first embodiment. [Figure 6]FIG. 6 is a block diagram showing an example of the configuration of an X-ray diagnostic apparatus according to the second embodiment. [Figure 7] FIG. 7 is a flowchart showing the procedure of processing in the X-ray diagnostic apparatus according to the second embodiment. [Figure 8] FIG. 8 is a block diagram showing an example of the configuration of a medical image processing apparatus according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, embodiments of an X-ray diagnostic apparatus, a medical image processing apparatus, and a program will be described in detail with reference to the drawings. Note that the X-ray diagnostic apparatus, the medical image processing apparatus, and the program according to the present application are not limited to the embodiments shown below.

[0009] (First embodiment) The configuration of an X-ray diagnostic apparatus according to the first embodiment will be described. FIG. 1 is a block diagram showing an example of the configuration of an X-ray diagnostic apparatus 1 according to the first embodiment. As shown in FIG. 1, a medical image processing apparatus 2 is connected to the X-ray diagnostic apparatus 1 via a network 3. The X-ray diagnostic apparatus 1 includes an X-ray high voltage device 11, an X-ray tube 12, an X-ray aperture 13, a tabletop 14, an X-ray detector 15, a C-arm 16, a processing circuit 17, an input interface 18, a display 19, and a memory circuit 20.

[0010] The medical image processing device 2 includes a processing circuit 21. The processing circuit 21 is configured by, for example, a processor. The processing circuit 21 acquires X-ray image data from the X-ray diagnostic device 1 and executes reconstruction of three-dimensional image data. Specifically, the processing circuit 21 reads out and executes a program stored in a storage circuit (not shown) to function as a reconstruction function 211 and reconstruct three-dimensional reconstruction data. The reconstruction function 211 is an example of a reconstruction unit. Details of the reconstruction function 211 will be described later.

[0011] The X-ray high voltage device 11 generates a high voltage under the control of the processing circuit 17, and applies the high voltage to the X-ray tube 12. The X-ray tube 12 irradiates X-rays toward the subject P placed on the top board 14 based on the high voltage applied by the X-ray high voltage device 11. The X-ray aperture 13 opens and closes aperture blades under the control of the processing circuit 17, and forms an irradiation range (irradiation field) of the X-rays irradiated from the X-ray tube 12. For example, the aperture blades are formed in a flat plate shape from a material such as lead that blocks X-rays. The top board 14 is a bed on which the subject P rests, and is placed on a couch (not shown).

[0012] The X-ray detector 15 is, for example, an X-ray flat panel detector (FPD) having detection elements arranged in a matrix. The X-ray detector 15 detects X-rays irradiated from the X-ray tube 12 and transmitted through the subject P, and outputs a detection signal corresponding to the detected X-ray amount to the processing circuit 17. The X-ray detector 15 according to the first embodiment will be described with reference to FIG. 2. FIG. 2 is a diagram showing an example of the configuration of the X-ray detector 15 according to the first embodiment. Here, FIG. 2 shows a cross section in a direction perpendicular to the X-ray incidence surface in the X-ray detector 15. For example, as shown in FIG. 2, the X-ray detector 15 has a first photodetector 15a, a second photodetector 15b, and a scintillator 15c. The first detector is composed of the first photodetector 15a and the scintillator 15c, and the second detector is composed of the second photodetector 15b and the scintillator 15c.

[0013] The scintillator 15c converts the X-rays irradiated from the X-ray tube 12 into light. The first photodetector 15a includes, for example, a two-dimensional image sensor using a TFT (Thin Film Transistor) array, detects the light converted by the scintillator 15c, and outputs an electric signal. The second photodetector 15b includes, for example, a two-dimensional image sensor using a CMOS (Complementary Metal Oxide Semiconductor) transistor, detects the light converted by the scintillator 15c, and outputs an electric signal. The first photodetector 15a and the second photodetector 15b share the scintillator 15c. As a result, the first photodetector 15a and the second photodetector 15b simultaneously detect the light converted by the scintillator 15c and output detection signals, respectively. That is, the X-ray detector 15 can collect images in the first detector and the second detector by one X-ray irradiation.

[0014] As shown in FIG. 2, the first photodetector 15a and the second photodetector 15b each have a plurality of elements that are the constituent units of a pixel. Each element converts a fluorescent image obtained by incident X-rays into an electrical signal using a photodiode (Photo Diode: PD). FIG. 2 illustrates a case in which the first photodetector 15a has eight elements in one row, and the second photodetector 15b has eight elements in one row. Here, the pixel pitch of each element of the second photodetector 15b is smaller than the pixel pitch of the first photodetector 15a. In FIG. 2, the pixel pitch of one element of the first photodetector 15a corresponds to the pixel pitch of two elements of the second photodetector 15b. Here, the size relationship between the pixel sizes of the first photodetector 15a and the second photodetector 15b is the same as the pixel pitch described above.

[0015] In addition, in the XY plane (plane on which X-rays are incident) of the X-ray detector 15 shown in FIG. 2, one element of the first photodetector 15a corresponds to four elements of the second photodetector 15b. Therefore, the second photodetector 15b has a higher resolution than the first photodetector 15a. Also, as shown in FIG. 2, the first photodetector 15a has a wider field of view size than the second photodetector 15b. For these reasons, the second photodetector 15b collects detection signals corresponding to high-resolution X-ray image data in an area overlapping with the first photodetector 15a.

[0016] The C-arm 16 holds the X-ray tube 12 and the X-ray aperture 13, and the X-ray detector 15 so that they face each other with the subject P in between. The C-arm 16 has a drive mechanism such as a motor and an actuator, and rotates and moves by operating the drive mechanism under the control of a processing circuit 17 described later. Note that in FIG. 1, the X-ray diagnostic apparatus 1 is described as being a single plane, but the embodiment is not limited to this, and may be a biplane. Here, the C-arm 16 is one example of an arm.

[0017] The processing circuitry 17 is composed of, for example, a processor. The processing circuitry 17 controls the control function 171, the acquisition function 172, and the processing function 173, thereby controlling the entire X-ray diagnostic apparatus 1. Specifically, the control function 171 supplies control signals to the X-ray high voltage device 11, the X-ray tube 12, the X-ray aperture 13, the tabletop 14, the X-ray detector 15, and the C-arm 16, and causes them to irradiate X-rays. The control function 171 also generates X-ray image data based on a detection signal detected by the X-ray detector 15, and stores the generated X-ray image data in the memory circuitry 20. The control function 171 also causes the display 19 to display an X-ray image.

[0018] The acquisition function 172 acquires X-ray image data. The processing function 173 performs image processing on the X-ray image data to generate an X-ray image. Furthermore, the processing function 173 stores the generated X-ray image in the memory circuitry 20. Here, the control function 171 is an example of a control unit. Furthermore, the acquisition function 172 is an example of an acquisition unit. Furthermore, the processing function 173 is an example of a processing unit. Note that details of the control function 171, the acquisition function 172, and the processing function 173 will be described later.

[0019] The input interface 18 is composed of an input device that accepts various input operations from a user. The input interface 18 accepts an input operation from a user and outputs an electrical signal corresponding to the accepted input operation to the processing circuit 17. For example, the input interface 18 is composed of various buttons such as a mouse, a keyboard, a trackball, and an exposure switch, a touchpad that performs an input operation by touching the operation surface, a touch screen in which a display screen and a touchpad are integrated, a non-contact input circuit using an optical sensor, a voice input circuit, and the like. The input interface 18 may be composed of a tablet terminal or the like that can wirelessly communicate with the device body. In addition, the input interface 18 is not limited to only those that have physical operation parts such as a mouse and a keyboard. For example, an example of the input interface 18 includes an electrical signal processing circuit that receives an electrical signal corresponding to an input operation from an external input device provided separately from the device and outputs the electrical signal to the processing circuit 17.

[0020] The display 19 is configured with a display device that displays various information. For example, the display 19 displays a GUI (Graphical User Interface), an X-ray image, and the like under the control of the processing circuitry 17.

[0021] The memory circuitry 20 is composed of, for example, semiconductor memory elements such as a random access memory (RAM) or a flash memory, a hard disk, an optical disk, etc., and stores various information, various data, and various programs. For example, the memory circuitry 20 stores a graphical user interface (GUI), an X-ray image, X-ray image data, etc. The memory circuitry 20 also stores a program that is executed by the processing circuitry 17 and causes the processing circuitry 17 to function as a control function 171, an acquisition function 172, and a processing function 173.

[0022] An example of the configuration of the X-ray diagnostic device 1 according to this embodiment has been described above. With such a configuration, the X-ray diagnostic device 1 of this embodiment makes it possible to generate a three-dimensional image with high accuracy. Specifically, in image collection using an X-ray detector that can collect images with multiple detectors by one X-ray irradiation, the X-ray diagnostic device 1 makes it possible to obtain three-dimensional image data with higher image quality based on images collected by a relatively small detector.

[0023] The X-ray diagnostic apparatus 1 can perform rotational imaging in which the X-ray tube 12 and the X-ray detector 15 are rotated by the C-arm 16 to image the subject P at each rotation angle. By performing this rotational imaging, it is possible to reconstruct three-dimensional image data using images at each rotation angle. Such reconstruction of three-dimensional image data can be performed for each of image data (first image data) collected by a first detector with a large field of view, and image data (second image data) collected by a second detector with a smaller field of view and higher resolution than the first detector.

[0024] However, when three-dimensional image data is reconstructed using the second image data, peripheral information of the three-dimensional image is insufficient, which may result in, for example, artifacts due to truncation.

[0025] An artifact according to the first embodiment will be described with reference to FIG. 3. FIG. 3 is a diagram for explaining an artifact according to the first embodiment. Here, FIG. 3 shows the positional relationship between the first detector, the second detector, and the target part of the subject P, and the corresponding relationship between the imaging range of the image data collected by each detector. For example, the first photodetector 15a is a square with a side of A inches, and collects pixel values ​​(dotted line + solid line) of the side of A inches by transmitted X-rays. The second photodetector 15b is a square with a side of B inches, and collects pixel values ​​(solid line) of the side of B inches by transmitted X-rays. Here, it is assumed that the size of the target part of the subject P irradiated with X-rays is larger than B inches and smaller than A inches as shown in FIG. 3. In such a case, the target part will be out of the imaging range (imaging field of view) of the second image data. Then, when reconstruction is performed using the second image data, there may be a case where artifacts occur due to a lack of information on the peripheral part of the imaging field of view required for imaging the target part by three-dimensional reconstruction. This is because when performing 3D reconstruction, the peripheral parts of the 3D reconstruction data are reconstructed using not only the corresponding image data but also the peripheral information of the rendering range. In this embodiment, the lack of information is called truncation.

[0026] Other causes of such truncation include the target region being outside the imaging range of the image data due to imaging geometry, which refers to the geometric positional relationship between the X-ray tube 12, the target region, and the X-ray detector 15. When three-dimensional image data is reconstructed using image data in which such truncation has occurred, artifacts occur at the edges of the three-dimensional image data.

[0027] In addition, since the MAR (Metal Artifact Reduction) correction used to remove metal artifacts also uses peripheral information of the image, when using an image collected by a second detector with a relatively small field of view and high resolution, the peripheral information of the image is insufficient, making it difficult to perform MAR correction. For example, in the treatment of an aneurysm, a device such as a coil may be placed in the body, and X-rays may be taken for observation after placement. At that time, metal artifacts occur due to extreme differences in X-ray absorption. In order to perform MAR correction for such metal artifacts, it is necessary to supplement the insufficient peripheral information for the image collected by the detector with a small field of view.

[0028] Therefore, in the X-ray diagnostic apparatus of this embodiment, peripheral information of the second image data collected by the second detector, which has a relatively small field of view and high resolution, is supplemented from the first image data collected by the first detector, which has a large field of view, making it possible to obtain three-dimensional image data based on the second image data with higher image quality.

[0029] The acquiring function 172 acquires first image data collected sequentially based on the detection signal output by the first photodetector 15a and second image data collected sequentially based on the detection signal output by the second photodetector 15b. Specifically, the acquiring function 172 acquires first image data consisting of a plurality of images collected at each rotation angle during rotational imaging of the subject, and second image data consisting of a plurality of images collected at each rotation angle.

[0030] For example, the acquisition function 172 acquires first image data with a large field of view and second image data with a small field of view and high resolution, which are collected at each rotation angle of the rotational imaging.

[0031] The processing function 173 determines an out-of-field area, which is an area in the first image data that supplements information in the second image data. Specifically, the processing function 173 determines the out-of-field area from an area in the first image data other than the area that overlaps with the second image data.

[0032] For example, the processing function 173 determines, as the out-of-field area, an area obtained by extending the area of ​​the first image data other than the area overlapping with the second image data in a direction perpendicular to the rotation axis direction in the rotational imaging, in the area of ​​the first image data. The size of the out-of-field area can be set arbitrarily. The out-of-field area may be determined by the user operating the input interface 18 to input, or a default value may be set in advance by the user. Alternatively, the X-ray diagnostic apparatus 1 may determine the out-of-field area according to the field of view size of the second image data.

[0033] FIG. 4 is a diagram showing an example of an outside-of-field region according to the first embodiment. The first image data and the second image data collected by the X-ray detector 15 are assumed to overlap so that the central coordinates of each image data match. Here, the direction of the rotation axis in the rotational imaging is defined as the y-axis. Also, the direction perpendicular to the rotation axis direction on the plane in FIG. 4 is defined as the x-axis. As shown in FIG. 4, the processing function 173 determines an area R1 in the first image data that does not overlap with the second image data and is adjacent to the second image in the x-axis direction as an outside-of-field region.

[0034] The processing function 173 converts the pixel size of the out-of-field area according to the pixel size of the second image data. Specifically, the processing function 173 converts (matrix converts) the pixel size of the out-of-field area in the first image data into the pixel size of the second image data. The second image data has a smaller pixel size than the first image data including the out-of-field area, and the pixel sizes are different. Therefore, in order to perform 3D reconstruction processing on the second image data supplemented with the image data of the out-of-field area, the out-of-field area in the first image data is divided and converted to match the pixel size of the second image data.

[0035] For example, a case will be described in which the pixel size of the first image data is α, the pixel size of the second image data is β, and the number of pixels of each image data is the same. In this case, the processing function 173 converts the number of pixels of one side of the first image data to be matrix converted by multiplying it by (α / β). Here, the image data to be matrix converted may be not only the area outside the field of view of the first image data, but also an area extended in the x-axis direction wider than the area outside the field of view of the first image data.

[0036] The processing function 173 converts the pixel level in the out-of-field region so as to match the pixel level of the first image data with the pixel level of the second image data. Specifically, the processing function 173 converts (gain converts) the pixel level of the matrix-converted image data including the out-of-field region in the first image data to the pixel level of the second image data. By performing this gain conversion, each detector outputs the transmitted X-rays collected by the first detector and the second detector through the same path with the same gain. This allows the gain-converted image data to be subjected to three-dimensional reconstruction processing under the same reconstruction conditions as the second image data. Here, the image data to be subjected to gain conversion is similar to the image data to be subjected to matrix conversion, but when the image data to be subjected to matrix conversion includes other regions in addition to the out-of-field region, the out-of-field region and other regions may be subjected to gain conversion.

[0037] The processing function 173 supplements the second image data with information on the out-of-field area in the first image data for each rotation angle. Specifically, the processing function 173 generates composite data by combining image data of the out-of-field area of ​​the first image data, which has been subjected to matrix conversion and gain conversion, with the second image data. In FIG. 4, the composite data is image data in which the second image and the out-of-field area are combined.

[0038] The processing function 173 transmits the composite data to the medical image processing device 2 via the network 3. The reconstruction function 211 in the medical image processing device 2 reconstructs three-dimensional image data using the composite data received from the X-ray diagnostic device 1. Here, the reconstruction process may be performed by a known method. For example, a filtered back projection (FBP) method, an iterative reconstruction method, etc. may be mentioned.

[0039] Next, the procedure of processing by the X-ray diagnostic apparatus 1 will be described. Fig. 5 is a flowchart showing the procedure of processing by the X-ray diagnostic apparatus 1 according to the first embodiment. Step S101 in Fig. 5 is realized by the processing circuitry 17 reading out a program corresponding to the acquisition function 172 from the storage circuitry 24 and executing it. Moreover, steps S102 to S105 are realized by the processing circuitry 17 reading out a program corresponding to the processing function 173 from the storage circuitry 24 and executing it. Moreover, step S106 is realized by the processing circuitry 21 in the medical image processing apparatus 2 reading out a program corresponding to the reconstruction function 211 from a storage circuitry (not shown) of the medical image processing apparatus 2 and executing it.

[0040] As shown in FIG. 5, the processing circuitry 17 collects image data (step S101) and determines an out-of-field area (step S102). Then, the processing circuitry 17 converts the pixel size of the first image data (step S103) and performs pixel level conversion (step S104). Next, the processing circuitry 17 supplements the second image data using the out-of-field area information (step S105). Then, the processing circuitry 21 performs 3D reconstruction (step S106). Here, the order of steps described in the flowchart of FIG. 5 is an example, and the order of the steps may be changed.

[0041] As described above, according to the first embodiment, the X-ray detector 15 includes a scintillator 15c that converts X-rays irradiated from the X-ray tube 12 into light, a first photodetector 15a that shares the scintillator 15c and outputs a detection signal according to the light converted by the scintillator 15c, and a second photodetector 15b that has a smaller field of view than the first photodetector 15a. The acquisition function 172 rotates the X-ray detector 15 around the subject P using the C-arm 16 that supports the X-ray detector 15, and acquires first image data sequentially collected based on the detection signal output by the first photodetector 15a and second image data sequentially collected based on the detection signal output by the second photodetector 15b. The processing function 173 supplements the second image data for each rotation angle of the X-ray detector 15 using outside-field-of-view area information, which is information on an image area other than the area of ​​the second image data in the first image data. As a result, the X-ray diagnostic apparatus 1 supplements the information of the peripheral portion of the second image data, so that it is possible to reduce the occurrence of artifacts when performing 3D reconstruction. This makes it possible to generate 3D images with high accuracy. In turn, the surgeon can perform the procedure more accurately and safely by referring to the high-accuracy 3D images.

[0042] Furthermore, according to the first embodiment, the processing function 173 converts the pixel size of the out-of-field area information according to the pixel size of the second image data, and uses the converted out-of-field area information to supplement the second image data. As a result, the composite data, which is the second image data supplemented with the converted out-of-field area information, has a uniform pixel size. Therefore, the X-ray diagnostic apparatus 1 can uniformly perform 3D reconstruction for two types of image data with different resolutions collected by different detectors, making it possible to generate 3D images with high accuracy.

[0043] Also, according to the first embodiment, the processing function 173 converts the pixel level in the out-of-field area information so as to match the pixel level of the first image data with the pixel level of the second image data, and uses the converted out-of-field area information to supplement the second image data. As a result, the pixel level of the composite data, which is the second image data supplemented by the converted out-of-field area information, is matched. Therefore, the X-ray diagnostic device 1 makes it possible to generate a 3D image with high accuracy, since the output levels of the transmitted X-rays collected by the different detectors are aligned and 3D reconstruction can be uniformly performed on the composite data.

[0044] According to the first embodiment, the second photodetector 15b has a higher resolution than the first photodetector 15a. This allows the X-ray diagnostic device 1 to generate a high-definition three-dimensional image. For example, when observing minute blood vessels running around a cerebral aneurysm in the treatment of the aneurysm, the X-ray diagnostic device 1 can accurately depict a site with a minute shape.

[0045] Moreover, according to the first embodiment, the reconstruction function 211 reconstructs three-dimensional image data based on the second image data supplemented with the out-of-field area information. This allows the X-ray diagnostic apparatus 1 to supplement the information on the peripheral parts of the second image data, thereby reducing the occurrence of artifacts when three-dimensional reconstruction is performed. This makes it possible to generate a three-dimensional image with high accuracy.

[0046] (Variation 1) In the above-described first embodiment, the reconstruction function 211 of the medical image processing apparatus 2 reconstructs three-dimensional image data. However, the embodiment is not limited to this, and the three-dimensional reconstruction process may be executed by the X-ray diagnostic apparatus 1. In this case, a program for causing the reconstruction function 211 to function, which is stored in the storage circuitry of the medical image processing apparatus 2, is stored in correspondence with the storage circuitry 20 of the X-ray diagnostic apparatus 1. Then, the processing circuitry 17 reads out the program corresponding to the reconstruction function 211 from the storage circuitry 20 and executes it, thereby performing the same process as the reconstruction function 211. Specifically, the processing circuitry 17 reconstructs three-dimensional image data using the generated composite data.

[0047] Second Embodiment In the first embodiment, a case has been described in which the X-ray diagnostic apparatus 1 collects image data from the X-ray detector 15 in which the coordinate center of the first photodetector 15a coincides with the coordinate center of the second photodetector 15b, and generates composite data based on out-of-field area information. In the second embodiment, a process by the X-ray diagnostic apparatus 1 in the case in which there is a deviation between the coordinate center of the first photodetector 15a and the coordinate center of the second photodetector 15b is described. Specifically, in the second embodiment, a case has been described in which image data is collected from the X-ray detector 15, the position deviation is corrected, and composite data is generated based on the corrected out-of-field area information.

[0048] 6 is a block diagram showing an example of the configuration of an X-ray diagnostic apparatus 1 according to the second embodiment. The X-ray diagnostic apparatus 1 according to the second embodiment is different from the X-ray diagnostic apparatus 1 according to the first embodiment in that the processing circuitry 17 further executes a calibration function 174. The following description will focus on the differences from the first embodiment.

[0049] The processing function 173 supplements the second image data using information on the out-of-field area calculated according to the positional relationship between the first photodetector 15a and the second photodetector 15b. Specifically, the processing function 173 generates composite data using information on the out-of-field area after correcting the positional shift between the first image data and the second image data caused by the positional shift between the first photodetector 15a and the second photodetector 15b.

[0050] Here, the processing function 173 can correct the positional deviation by using information on the positional deviation between the photodetectors or information on the positional deviation between the image data. These will be described below in order.

[0051] First, the correction of the positional deviation using the information on the positional deviation between the photodetectors will be described. The processing function 173 calculates the outside field of view area information using the first image data and the second image data whose positional relationship has been corrected based on the information on the positional deviation between the first photodetector 15a and the second photodetector 15b. Specifically, the processing function 173 calculates the information on the positional deviation (positional correction information) that occurs between the first photodetector 15a and the second photodetector 15b. Here, the positional deviation calculated by the processing function 173 includes the following two types of deviation. The first is the positional deviation of the center coordinates (center) of each photodetector. The second is the deviation in the direction of the rotation axis of the photodetector that occurs when one photodetector rotates relative to the other photodetector. Then, the processing function 173 corrects the positional deviation by changing the position (pixel shift) of the first image data relative to the second image data based on the calculated positional correction information.

[0052] The position correction information described above is calculated, for example, by X-ray photography using a phantom. In a situation such as calibration performed before photography of the subject P, the X-ray diagnostic apparatus 1 performs X-ray photography using the phantom as an irradiation target, and collects first image data and second image data one by one. The processing function 173 calculates the positional deviation amount (X, Y) in the x-axis and y-axis directions of one image data relative to the other image data in the first image data and the second image data, using the image data collected one by one using the phantom as an irradiation target. Here, the position correction information in this embodiment is represented as (X, Y, φ). The processing function 173 stores the calculated position correction information (X, Y, φ) in the memory circuitry 20.

[0053] Thereafter, the processing function 173 processes the first image data and the second image data, which are acquired by the acquisition function 172 for the subject P and consist of a plurality of images, and executes a correction process based on the position correction information. For example, the processing function 173 corrects the positional deviation between the first image data and the second image data by moving (pixel shifting) one of the first image data and the second image data relative to the other image data based on the position correction information. Here, the processing function 173 uniformly executes the pixel shift described above for the image data collected for each rotation angle θ of the X-ray detector 15. This allows the processing function 173 to correct the positional deviation between the image data resulting from the positional deviation between the photodetectors.

[0054] As a method for calculating the position correction information, a case has been described in which a phantom is defined as an irradiation target, X-rays are taken, and the position correction information is calculated using the obtained image data, but the embodiment is not limited to this. For example, if the X-ray diagnostic device 1 includes a sensor that measures the positional deviation between the photodetectors, the position correction information may be calculated using the sensor.

[0055] Next, the correction of the positional deviation using the information of the positional deviation between the image data will be described. The processing function 173 calculates the out-of-field area information using the first image data and the second image data whose positional relationship has been corrected for each rotation angle based on the information on the positional deviation between the first image data and the second image data for each rotation angle. Specifically, the processing function 173 calculates the information on the positional deviation occurring between the pair of the first image data and the second image data having the same rotation angle obtained by the rotational imaging. The information on the positional deviation is the above-mentioned position correction information (X, Y, φ) collected for each rotational angle θ of the detector in the rotational imaging. Then, the processing function 173 executes the pixel shift for the pair of the first image data and the second image data corresponding to the rotational angle θ based on the calculated position correction information. Thereby, the processing function 173 can correct the positional deviation even if the positional deviation occurs between the photodetectors during the rotational imaging.

[0056] For example, the processing function 173 calculates position correction information (X, Y, φ) for each rotation angle θ using the first image data and the second image data obtained by performing rotational imaging on the subject P. Here, the position correction information is calculated from the positional relationship of the detected object by detecting the subject P or an object (such as a device) depicted in common in a pair of image data corresponding to a certain rotation angle θ through image processing, for example. However, the image processing may be performed by a known method. Then, the processing function 173 executes pixel shift of one image data of the first image data and the second image data relative to the other image data for each frame based on the calculated position correction information. In this way, the processing function 173 can correct the positional deviation between the image data derived from the positional deviation between the photodetectors during rotational imaging.

[0057] In addition, the above-mentioned information on the positional deviation between image data is calculated based on image data collected by performing rotational imaging on the subject P, but the embodiment is not limited to this. For example, the position correction information may be calculated using image data based on rotational imaging collected in the past. This is because, if it is expected that the positional deviation between the photodetectors for each rotation angle θ also occurred in the past rotational imaging, the position correction information is considered to be common. Therefore, the processing function 173 may correct the positional deviation between image data using the position correction information calculated in the past, without calculating new position correction information every time rotational imaging is performed. Here, the subject related to the rotational imaging collected in the past may be the same as the subject P related to the target image data to be corrected for positional deviation, or may be a different subject.

[0058] Moreover, the above-mentioned correction of positional deviation using the information on the positional deviation between image data can be used to create three-dimensional calibration data related to rotational imaging. For example, as one of the maintenance of the X-ray diagnostic device 1, three-dimensional calibration is performed on each of the first detector and the second detector, and three-dimensional calibration data for each detector is created. Here, the three-dimensional calibration data referred to in this embodiment indicates which pixel electrode (cell) in each detector collected each transmitted X-ray emitted from the X-ray tube and transmitted through the irradiation target for each rotation angle θ. For example, the three-dimensional calibration data indicates the correspondence between the rotation angle and the coordinate data depicting the irradiation target on the XY plane on which the X-ray of the detector is incident. The three-dimensional calibration can correct the positional deviation of the image data by using the three-dimensional calibration data so that the transmitted X-ray can be collected without changing the correspondence between the X-ray focus and the cell of the X-ray detector 15 during rotational imaging. However, since the X-ray detector 15 has two different photodetectors, the three-dimensional calibration is performed twice, and it takes time to collect the three-dimensional calibration data.

[0059] Therefore, the calibration function 174 generates calibration data (second calibration data) for the second photodetector 15b using the positional relationship between the first photodetector 15a and the second photodetector 15b and the calibration data (first calibration data) for the first photodetector 15a. Here, the positional relationship between the first photodetector 15a and the second photodetector 15b is position correction information (X, Y, φ) calculated for each rotation angle θ using the first image data and the second image data obtained by rotational shooting. For example, the calibration function 174 creates the second calibration data using the above-mentioned position correction information and the first calibration data created based on the first image data.

[0060] For example, the position correction information and the first calibration data are obtained by performing rotational imaging of a phantom as an irradiation target. When the rotational imaging is performed, the acquisition function 172 acquires first image data and second image data. Then, the processing function 173 calculates the position correction information using the acquired image data. The calibration function 174 creates the first calibration data based on the first image data. Then, the calibration function 174 creates the second calibration data by correcting the first calibration data based on the position correction information, using the calculated position correction information indicating the positional relationship between the photodetectors.

[0061] The calibration data of the first photodetector 15a may be created using the position correction information and the calibration data of the second photodetector 15b. Specifically, the calibration function 174 generates the calibration data of the first photodetector 15a using the positional relationship between the first photodetector 15a and the second photodetector 15b and the calibration data of the second photodetector 15b. Here, the positional relationship between the first photodetector 15a and the second photodetector 15b is the position correction information (X, Y, φ) calculated for each rotation angle θ. The calibration function 174 creates the second calibration data based on the second image data. Then, the calibration function 174 creates the calibration data of the first photodetector 15a by correcting the calibration data of the second photodetector 15b based on the position correction information, using the calculated position correction information indicating the positional relationship between the photodetectors.

[0062] (Variation 1) Furthermore, the reconstruction process of the three-dimensional image data in the second embodiment described above is not limited to being performed by the medical image processing device 2, as in the first modification example of the first embodiment, but may be performed by the X-ray diagnostic device 1. In such a case, the processing circuitry 17 reconstructs the three-dimensional image data using the generated composite data.

[0063] Next, the procedure of processing by the X-ray diagnostic apparatus 1 will be described. FIG. 7 is a flowchart showing the procedure of processing by the X-ray diagnostic apparatus 1 according to the second embodiment. Step S201 in FIG. 7 is realized by the processing circuitry 17 reading out a program corresponding to the acquisition function 172 from the storage circuitry 24 and executing it. Moreover, step S202 and steps S204 to S206 are realized by the processing circuitry 17 reading out a program corresponding to the processing function 173 from the storage circuitry 24 and executing it. Moreover, step S203 is realized by the processing circuitry 17 reading out a program corresponding to the calibration function 174 from the storage circuitry 24 and executing it. Moreover, step S207 is realized by the processing circuitry 21 in the medical image processing apparatus 2 reading out a program corresponding to the reconstruction function 211 from a storage circuitry (not shown) of the medical image processing apparatus 2 and executing it.

[0064] As shown in FIG. 7, the processing circuitry 17 collects image data (step S201) and determines an out-of-field area (step S202). Then, the processing circuitry 17 corrects the positional relationship (step S203). Furthermore, the processing circuitry 17 converts the pixel size of the first image data (step S204) and performs pixel level conversion (step S205). Next, the processing circuitry 17 supplements the second image data using the out-of-field area information (step S206). Then, the processing circuitry 21 performs three-dimensional reconstruction (step S207). Here, the order of steps described in the flowchart of FIG. 7 is an example, and the order of each step may be reversed. For example, the correction of the positional relationship (step S203) may be performed after the collection of image data (step S201) and before the three-dimensional reconstruction (step S207).

[0065] As described above, according to the second embodiment, the processing function 173 supplements the second image data using out-of-field area information calculated according to the positional relationship between the first photodetector 15a and the second photodetector 15b. This makes it possible to calculate the positional relationship of the image data derived from the positional relationship between the photodetectors. Then, by calculating the out-of-field area information based on the calculated positional relationship, it is possible to generate composite data supplemented with the second image data with high accuracy. This in turn makes it possible to generate a three-dimensional image with high accuracy.

[0066] Furthermore, according to the second embodiment, the processing function 173 calculates out-of-field area information using the first image data and the second image data whose positional relationship has been corrected based on information regarding the positional deviation between the first photodetector 15a and the second photodetector 15b. This makes it possible to correct the positional deviation between the image data resulting from the positional deviation between the photodetectors. Then, the out-of-field area information is calculated based on the corrected image data, and the second image data is supplemented to generate composite data with high accuracy, making it possible to generate a three-dimensional image with high accuracy.

[0067] Furthermore, according to the second embodiment, the processing function 173 calculates out-of-field area information using the first image data and the second image data, the positional relationship of which has been corrected for each rotation angle, based on information regarding the positional deviation between the first image data and the second image data for each rotation angle. This makes it possible to correct the positional deviation between the image data for each rotation angle, which is caused by the positional deviation between the photodetectors in the rotational shooting. Then, the out-of-field area information is calculated based on the corrected image data, and the second image data is supplemented to generate composite data with high accuracy, making it possible to generate a three-dimensional image with high accuracy.

[0068] Furthermore, according to the second embodiment, the calibration function 174 generates calibration data for the second photodetector 15b using the positional relationship between the first photodetector 15a and the second photodetector 15b and the calibration data for the first photodetector 15a. This makes it possible to create calibration data based on the positional relationship between the photodetectors. Then, by calculating out-of-field area information based on the calculated positional relationship, it is possible to easily generate composite data that accurately supplements the second image data.

[0069] Furthermore, according to the second embodiment, the calibration function 174 generates calibration data for the first photodetector 15a using the positional relationship between the first photodetector 15a and the second photodetector 15b and the calibration data for the second photodetector 15b. This makes it possible to create calibration data based on the positional relationship between the photodetectors. Then, by calculating out-of-field area information based on the calculated positional relationship, it is possible to easily generate composite data that accurately supplements the second image data.

[0070] (Other embodiments) In the first and second embodiments, an example in which the X-ray diagnostic apparatus 1 performs image processing has been described. However, the embodiments are not limited to this, and the medical image processing apparatus 2 may execute the image processing according to the present application. FIG. 8 is a block diagram showing an example of the configuration of the medical image processing apparatus 2 according to another embodiment. The medical image processing apparatus 2 is, for example, a server apparatus, a workstation, a viewer, a tablet, a PC (Personal Computer), etc. As shown in FIG. 8, the medical image processing apparatus 2 is connected to the X-ray diagnostic apparatus 1 via a network 3.

[0071] The medical image processing device 2 performs image processing on each image data collected by the X-ray diagnostic device 1 in response to a user's operation. The medical image processing device 2 has a processing circuit 21, an input interface 22, a display 23, a storage circuit 24, and a communication interface 25. Here, the input interface 22, the display 23, and the storage circuit 24 are similar to the configurations of the X-ray diagnostic device 1 according to the first and second embodiments, so their description will be omitted. The processing circuit 21 according to the other embodiments differs from the first and second embodiments in that it executes an acquisition function 212, a processing function 213, and a calibration function 214. The acquisition function 212 controls the communication interface 25 and collects image data via the network 3. The processing function 213 executes the same processing as the processing function 173 described in the first and second embodiments. In addition, the calibration function 214 executes the same processing as the calibration function 174 described in the second embodiment. In addition, the reconstruction function 211 according to the other embodiments executes the same processing as the processing described in the first and second embodiments.

[0072] The communication interface 25 is composed of a communication device such as a network card, a network adapter, or a NIC (Network Interface Controller). Under the control of the processing circuitry 21, the communication interface 25 communicates with the medical image processing device 2 connected via the network 3. For example, the communication interface receives each image data from the X-ray diagnostic apparatus 1 and stores it in the memory circuitry 24.

[0073] Furthermore, the correction of image data resulting from the above-mentioned positional deviation between the photodetectors and the creation of calibration data may be performed in the medical image processing device 2, or may be performed by the X-ray diagnostic device 1 at the instruction of the medical image processing device 2. That is, when the medical image processing device 2 performs the image processing according to the present application on the image data, a part of the processing may be executed by a corresponding function in the X-ray diagnostic device 1.

[0074] The term "processor" used in the description of the above-mentioned embodiment means a circuit such as a central processing unit (CPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), a programmable logic device (e.g., a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), and a field programmable gate array (FPGA)). Here, instead of storing a program in the memory circuit 20, the program may be directly built into the circuit of the processor. In this case, the processor realizes its function by reading and executing the program built into the circuit. In addition, each processor in the present embodiment is not limited to being configured as a single circuit for each processor, and may be configured as a single processor by combining multiple independent circuits to realize its function.

[0075] Here, the program executed by the processor is provided in advance in a ROM (Read Only Memory) or a storage circuit. The program may be provided by being recorded in a computer-readable non-transitory storage medium such as a CD (Compact Disk)-ROM, a FD (Flexible Disk), a CD-R (Recordable), or a DVD (Digital Versatile Disk) in a format that can be installed in these devices or in a format that can be executed. The program may also be provided or distributed by being stored on a computer connected to a network such as the Internet and downloaded via the network. For example, the program is composed of modules including each of the above-mentioned processing functions. As actual hardware, a CPU reads out the program from a storage medium such as a ROM and executes it, so that each module is loaded onto a main storage device and generated on the main storage device.

[0076] In addition, in the above-mentioned embodiment and modified examples, each component of each device shown in the figure is a functional concept, and does not necessarily have to be physically configured as shown in the figure. In other words, the specific form of distribution or integration of each device is not limited to that shown in the figure, and all or a part of it can be functionally or physically distributed or integrated in any unit according to various loads, usage conditions, etc. Furthermore, all or any part of each processing function performed by each device can be realized by a CPU and a program analyzed and executed by the CPU, or can be realized as hardware using wired logic.

[0077] Furthermore, among the processes described in the above-mentioned embodiments and modifications, all or part of the processes described as being performed automatically can be performed manually, or all or part of the processes described as being performed manually can be performed automatically by a known method. In addition, the information including the processing procedures, control procedures, specific names, various data and parameters shown in the above documents and drawings can be changed arbitrarily unless otherwise specified.

[0078] According to at least one of the embodiments described above, it is possible to generate a three-dimensional image with high accuracy.

[0079] Although some embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[0080] 1. X-ray diagnostic equipment 2 Medical image processing equipment 15 X-ray detector 16 C-arm 172, 212 Acquisition function 173, 213 Processing functions 174, 214 Calibration function 211 Reconfiguration function

Claims

1. an X-ray detector including a scintillator that converts X-rays emitted from an X-ray tube into light, a first photodetector that shares the scintillator and outputs a detection signal in response to the light converted by the scintillator, and a second photodetector that has a smaller field of view than the first photodetector; an acquisition unit that acquires first image data based on a detection signal output by the first photodetector and second image data based on a detection signal output by the second photodetector, the first image data being collected sequentially for each rotation angle during rotational imaging in which the X-ray detector rotates around a subject using an arm supporting the X-ray detector and captures images for each rotation angle; a processing unit that determines, for each rotation angle, an out-of-field area in an image area other than an area in the first image data that overlaps with the second image data, the out-of-field area being an extension of the area that overlaps with the second image data in a direction that is parallel to a detection surface of the X-ray detector when the first image data and the second image data were collected and perpendicular to a rotation axis direction in the rotational imaging, and generates composite data by combining image data in the first image data that corresponds to the out-of-field area with the second image data; a reconstruction unit that reconstructs three-dimensional image data using a plurality of synthetic data generated for each rotation angle; An X-ray diagnostic apparatus comprising:

2. 2. The X-ray diagnostic apparatus according to claim 1, wherein the processing unit converts a pixel size of the image data corresponding to the outside field of view area in accordance with a pixel size of the second image data, and combines the converted image data with the second image data.

3. 3. The X-ray diagnostic apparatus according to claim 1, wherein the processing unit converts a pixel level in image data corresponding to the outside field of view region so as to align a pixel level of the first image data with a pixel level of the second image data, and combines the converted image data with the second image data.

4. 4. The X-ray diagnostic apparatus according to claim 1, wherein the processing unit combines image data corresponding to the outside-of-field-of-view area calculated according to a positional relationship between the first photodetector and the second photodetector with the second image data.

5. 5. The X-ray diagnostic apparatus according to claim 4, wherein the processing unit calculates the outside field of view area using the first image data and the second image data, the positional relationship of which has been corrected based on information regarding a positional deviation between the first photodetector and the second photodetector.

6. 5. The X-ray diagnostic apparatus according to claim 4, wherein the processing unit calculates the outside field of view area using the first image data and the second image data, the positional relationship of which has been corrected for each rotation angle, based on information regarding a positional deviation between the first image data and the second image data for each rotation angle.

7. 7. The X-ray diagnostic apparatus according to claim 4, further comprising a calibration unit that generates calibration data for the second photodetector using a positional relationship between the first photodetector and the second photodetector and calibration data for the first photodetector.

8. 7. The X-ray diagnostic apparatus according to claim 4, further comprising a calibration unit that generates calibration data for the first photodetector by using a positional relationship between the first photodetector and the second photodetector and calibration data for the second photodetector.

9. 9. The X-ray diagnostic apparatus according to claim 1, wherein the second photodetector has a higher resolution than the first photodetector.

10. an acquisition unit that acquires first image data based on the detection signal output by the first photodetector and second image data based on the detection signal output by the second photodetector, the first image data being acquired by an X-ray detector having a scintillator that converts X-rays emitted from an X-ray tube into light, a first photodetector that shares the scintillator and outputs a detection signal in response to the light converted by the scintillator, and a second photodetector having a smaller field of view than the first photodetector, the first image data being acquired by an arm that supports the X-ray detector, during rotational imaging in which the X-ray detector rotates around a subject and captures images for each rotation angle; and a processing unit that determines, for each rotation angle, an out-of-field area in an image area other than an area in the first image data that overlaps with the second image data, the out-of-field area being an extension of the area that overlaps with the second image data in a direction that is parallel to a detection surface of the X-ray detector when the first image data and the second image data were collected and perpendicular to a rotation axis direction in the rotational imaging, and generates composite data by combining image data in the first image data that corresponds to the out-of-field area with the second image data; a reconstruction unit that reconstructs three-dimensional image data using a plurality of synthetic data generated for each rotation angle; A medical image processing device comprising:

11. On the computer, an acquisition function for acquiring first image data based on the detection signal output by the first photodetector and second image data based on the detection signal output by the second photodetector, the first image data being collected by an X-ray detector having a scintillator that converts X-rays emitted from an X-ray tube into light, a first photodetector that shares the scintillator and outputs a detection signal in response to the light converted by the scintillator, and a second photodetector having a smaller field of view than the first photodetector, the first image data being collected by an arm that supports the X-ray detector, during rotational imaging in which the X-ray detector rotates around the subject and captures images for each rotation angle, the first image data being collected by an arm that supports the X-ray detector, and second image data being collected by a rotation angle; a processing function for determining, for each rotation angle, an out-of-field area in an image area other than an area in the first image data that overlaps with the second image data, the out-of-field area being an area obtained by extending the area that overlaps with the second image data in a direction that is parallel to a detection surface of the X-ray detector when the first image data and the second image data are acquired and perpendicular to a direction of a rotation axis in the rotational imaging, and generating composite data by combining image data in the first image data that corresponds to the out-of-field area with the second image data; and a reconstruction function for reconstructing three-dimensional image data using the plurality of composite data generated for each rotation angle; A program to achieve this.

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