JP2022168979A - X-ray diagnostic device, medical image processing device, and program - Google Patents

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

The embodiments disclosed in this specification and drawings relate to an X-ray diagnostic apparatus, a medical image processing apparatus, and a program.

For example, in treating a cerebral aneurysm using an X-ray diagnostic apparatus, an X-ray image depicting a wide area of the subject is observed, and a high-resolution X-ray image may also be used to observe a region of interest. . An X-ray diagnostic apparatus used in such a case includes, for example, 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. X-ray diagnostic devices with ray detectors are known. Such an X-ray diagnostic apparatus uses X-ray detectors including a first detector and a second detector to simultaneously collect X-rays that have passed through a subject with each detector, thereby adjusting the field size and resolution. Two different X-ray images can be acquired.

The X-ray diagnostic apparatus can also reconstruct three-dimensional image data using a plurality of image data acquired by rotational imaging. Here, when reconstruction is performed using only a partial region included in the image data, artifacts may occur in the edge portion of the reconstructed three-dimensional image data. In order to reduce such artifacts, in X-ray diagnostic apparatuses, when reconstructing a partial area included in image data, there is known a technique of reconstructing data including surrounding data of the partial area. ing.

Japanese Unexamined Patent Application Publication No. 2011-200573

The problem to be solved by the embodiments disclosed in the specification and drawings is to enable accurate generation of a three-dimensional image. However, the problems to be solved by the embodiments disclosed in this specification and drawings are not limited to the above problems. A problem corresponding to each effect of each configuration shown in the embodiments described later can be positioned as another problem.

An X-ray diagnostic apparatus according to an embodiment includes an X-ray detector, an acquisition unit, and a processing unit. The X-ray detector includes a scintillator that converts X-rays emitted from the 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 having a smaller field of view than the first photodetector. The acquisition unit rotates the X-ray detector around the subject by an arm that supports the X-ray detector, and sequentially acquires first image data based on detection signals output from the first photodetector. and second image data sequentially acquired 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 out-of-field area information, which is information on an image area other than the area of the second image data in the first image data. .

FIG. 1 is a block diagram showing an example configuration of an X-ray diagnostic apparatus according to the first embodiment. FIG. 2 is a diagram illustrating an example of the configuration of the X-ray detector according to the first embodiment; FIG. 3 is a diagram for explaining artifacts according to the first embodiment. FIG. 4 is a diagram illustrating an example of an out-of-view area according to the first embodiment. FIG. 5 is a flow chart showing the procedure of processing of the X-ray diagnostic apparatus according to the first embodiment. FIG. 6 is a block diagram showing an example configuration of an X-ray diagnostic apparatus according to the second embodiment. FIG. 7 is a flow chart showing the processing procedure of the X-ray diagnostic apparatus according to the second embodiment. FIG. 8 is a block diagram showing an example configuration of a medical image processing apparatus according to another embodiment.

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, medical image processing apparatus, and program according to the present application are not limited to the embodiments described below.

(First embodiment)
The configuration of the X-ray diagnostic apparatus according to the first embodiment will be described. FIG. 1 is a block diagram showing an example configuration of an X-ray diagnostic apparatus 1 according to the first embodiment. As shown in FIG. 1 , an X-ray diagnostic apparatus 1 is connected to a medical image processing apparatus 2 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 diaphragm 13, a top plate 14, an X-ray detector 15, a C-arm 16, and a processing circuit 17. , an input interface 18 , a display 19 and a storage circuit 20 .

The medical image processing apparatus 2 has a processing circuit 21 . The processing circuit 21 is composed of, for example, a processor. The processing circuit 21 acquires X-ray image data from the X-ray diagnostic apparatus 1 and reconstructs three-dimensional image data. Specifically, the processing circuit 21 functions as a reconstruction function 211 by reading and executing a program stored in a storage circuit (not shown) to 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.

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 the subject P placed on the tabletop 14 with X-rays based on the high voltage applied by the X-ray high voltage device 11 . The X-ray diaphragm 13 opens and closes diaphragm blades under the control of the processing circuit 17 to form an irradiation range (irradiation field) of X-rays emitted from the X-ray tube 12 . For example, the diaphragm blades are formed in a flat plate shape from a material such as lead that shields X-rays. The top board 14 is a bed on which the subject P is placed, and is arranged on a bed (not shown).

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 emitted from the X-ray tube 12 and transmitted through the subject P, and outputs a detection signal corresponding to the detected X-ray dose to the processing circuit 17 . An X-ray detector 15 according to the first embodiment will be described with reference to FIG. 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 of the X-ray detector 15 in a direction perpendicular to the plane of incidence of X-rays. For example, the X-ray detector 15 has a first photodetector 15a, a second photodetector 15b, and a scintillator 15c, as shown in FIG. A first detector is composed of the first photodetector 15a and the scintillator 15c, and a second detector is composed of the second photodetector 15b and the scintillator 15c.

The scintillator 15c converts the X-rays emitted from the X-ray tube 12 into light. The first photodetector 15a includes, for example, a two-dimensional image sensor employing a TFT (Thin Film Transistor) array, detects light converted by the scintillator 15c, and outputs an electrical signal. The second photodetector 15b includes, for example, a two-dimensional image sensor employing a CMOS (Complementary Metal Oxide Semiconductor) transistor, detects light converted by the scintillator 15c, and outputs an electrical 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. That is, the X-ray detector 15 can collect images with the first detector and the second detector by one X-ray irradiation.

Further, as shown in FIG. 2, the first photodetector 15a and the second photodetector 15b each have a plurality of elements serving as pixel constituent units. Each element converts a fluorescent image obtained by incident X-rays into an electrical signal using a photodiode (PD). FIG. 2 illustrates the case where 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 for one element of the first photodetector 15a corresponds to the pixel pitch for 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.

In addition, in the XY plane (the plane on which X-rays are incident) of the X-ray detector 15 shown in FIG. Equivalent to. 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 than the second photodetector 15b. As described above, the second photodetector 15b collects detection signals corresponding to high-resolution X-ray image data in a region overlapping with the first photodetector 15a.

The C-arm 16 holds the X-ray tube 12, the X-ray diaphragm 13, and the X-ray detector 15 so as to face each other with the subject P interposed therebetween. 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, which will be described later. In FIG. 1, the case where the X-ray diagnostic apparatus 1 is a single plane is described as an example, but the embodiment is not limited to this, and may be a biplane. Here, the C-arm 16 is an example of an arm.

The processing circuit 17 is composed of, for example, a processor. The processing circuit 17 controls the overall X-ray diagnostic apparatus 1 by controlling the control function 171 , acquisition function 172 and processing function 173 . Specifically, the control function 171 supplies control signals to the X-ray high-voltage device 11, the X-ray tube 12, the X-ray diaphragm 13, the top plate 14, the X-ray detector 15, and the C-arm 16, Irradiation is performed. The control function 171 also generates X-ray image data based on the detection signal detected by the X-ray detector 15 and causes the storage circuit 20 to store the generated X-ray image data. The control function 171 also causes the display 19 to display an X-ray image.

Acquisition function 172 acquires X-ray image data. The processing function 173 performs image processing on X-ray image data to generate an X-ray image. Furthermore, the processing function 173 causes the storage circuit 20 to store the generated X-ray image. Here, the control function 171 is an example of a control unit. Also, the acquisition function 172 is an example of an acquisition unit. Also, the processing function 173 is an example of a processing unit. Details of the control function 171, the acquisition function 172, and the processing function 173 will be described later.

The input interface 18 is composed of an input device that receives various input operations from the user. The input interface 18 receives an input operation from a user and outputs an electrical signal corresponding to the received input operation to the processing circuit 17 . For example, the input interface 18 includes various buttons such as a mouse, a keyboard, a trackball, and an exposure switch, a touch pad that performs input operations by touching the operation surface, a touch screen that integrates the display screen and the touch pad, and an optical interface. It consists of a non-contact input circuit using a sensor, a voice input circuit, etc. Note that the input interface 18 may be composed of a tablet terminal or the like capable of wireless communication with the apparatus main body. Also, the input interface 18 is not limited to having physical operation parts such as a mouse and a keyboard. For example, 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. be

The display 19 is composed of a display device that displays various kinds of information. For example, the display 19 displays a GUI (Graphical User Interface), an X-ray image, etc. under the control of the processing circuit 17 .

The storage circuit 20 is composed of, for example, a RAM (Random Access Memory), a semiconductor memory device such as a flash memory, a hard disk, an optical disk, or the like, and stores various information, various data, and various programs. The storage circuit 20 stores, for example, a GUI (Graphical User Interface), X-ray images, X-ray image data, and the like. The storage circuit 20 also stores a program that is executed by the processing circuit 17 and causes the processing circuit 17 to function as a control function 171 , an acquisition function 172 , and a processing function 173 .

An example of the configuration of the X-ray diagnostic apparatus 1 according to this embodiment has been described above. With such a configuration, the X-ray diagnostic apparatus 1 of the present embodiment can accurately generate a three-dimensional image. Specifically, the X-ray diagnostic apparatus 1 can collect images by a relatively small detector in image collection using an X-ray detector that can collect images with a plurality of detectors by one X-ray irradiation. It is possible to obtain 3D image data based on with higher image quality.

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 and the subject P is imaged at each rotation angle. By performing this rotational imaging, it is possible to reconstruct three-dimensional image data using images at each rotational angle. Such reconstruction of three-dimensional image data includes image data (first image data) collected by a first detector that has a large field of view, and a smaller field of view and higher resolution than the first detector. It can be performed on each of the image data collected by the second detector (second image data).

However, when the 3D image data is reconstructed using the second image data, edge information of the 3D image is insufficient. This lack of edge information may result in, for example, truncation artifacts.

Artifacts according to the first embodiment will be described with reference to FIG. FIG. 3 is a diagram for explaining artifacts according to the first embodiment. Here, FIG. 3 shows the correspondence relationship between the positional relationship among the first detector, the second detector, and the target region of the subject P, and the rendering range of the image data acquired by each detector. . For example, the first photodetector 15a is a square of A inches on a side, and collects pixel values (dotted line+solid line) for one side of A inches by transmitted X-rays. The second photodetector 15b is a square of B inches on a side, and collects pixel values (solid line) for B inches on a side by transmitted X-rays. Here, it is assumed that the size of the target portion of the subject P irradiated with X-rays is larger than B inches and smaller than A inches as shown in FIG. In such a case, the target site protrudes from the rendering range (imaging field of view) of the second image data. Then, when reconstruction is performed using the second image data, artifacts may occur due to lack of information on the peripheral portion of the imaging field of view that is necessary when depicting the target site by three-dimensional reconstruction. . This is because, when performing three-dimensional reconstruction, the edge of the three-dimensional reconstruction data is reconstructed using not only the corresponding image data but also the peripheral information of the rendering range. In this embodiment, the lack of information described above is called truncation.

Another factor that causes such truncation is imaging geometry, which refers to the geometrical positional relationship between the X-ray tube 12, the target region, and the X-ray detector 15. For example, it may exceed the range. When 3D image data is reconstructed using image data in which such truncation has occurred, artifacts occur in the edge portion of the 3D image data.

In addition, since the peripheral information of the image is also used in the MAR (Metal Artifact Reduction) correction used when removing metal artifacts, the image collected by the second detector with a relatively small field of view and high resolution is used. In this case, it is difficult to carry out MAR correction due to lack of peripheral information of the image. For example, in treating an aneurysm, a device such as a coil may be placed in the body, and X-ray imaging may be performed for observation after placement. In doing so, metal artifacts arise due to the extreme differential absorption of X-rays. In order to perform MAR correction for such metal artifacts, it is necessary to supplement the missing peripheral information for images collected by small field-of-view detectors.

Therefore, in the X-ray diagnostic apparatus of the present embodiment, the peripheral information of the second image data collected by the second detector with a relatively small field of view and high resolution is transferred to the first detector with a large field of view. Supplementing from the first image data collected by the device makes it possible to obtain three-dimensional image data based on the second image data with higher image quality.

The acquisition function 172 sequentially collects first image data based on the detection signal output from the first photodetector 15a and based on the detection signal output from the second photodetector 15b. and the second image data obtained. Specifically, the acquisition function 172 acquires first image data consisting of a plurality of images acquired at each rotation angle and second image data consisting of a plurality of images acquired at each rotation angle during rotational imaging of the subject. Get data.

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 definition, which are collected at each rotation angle of rotational photography.

Processing function 173 determines an out-of-view region, which is the region within the first image data that supplements the information for the second image data. Specifically, the processing function 173 determines an out-of-field region from regions other than regions overlapping with the second image data in the first image data.

For example, the processing function 173 extends the region overlapping the second image data in the direction perpendicular to the rotation axis direction in rotational imaging in the region other than the region overlapping the second image data in the first image data. area is determined as an out-of-field area. Note that the size of the out-of-field region can be set arbitrarily. Also, the out-of-field-of-view area may be determined by the user operating the input interface 18 for input, or the user may determine a default value in advance. Alternatively, the X-ray diagnostic apparatus 1 may determine the out-of-field area according to the size of the field of view of the second image data.

FIG. 4 is a diagram illustrating an example of an out-of-view area according to the first embodiment. It is assumed that the first image data and the second image data collected by the X-ray detector 15 overlap such that the central coordinates of each image data match. Here, the rotation axis direction in 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 converts a region R1 in the first image data that does not overlap with the second image data and that is adjacent to the second image in the x-axis direction to an out-of-field region. and decide.

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 conversion) the pixel size of the out-of-field region in the first image data into the pixel size of the second image data. The second image data has a smaller pixel size and a different pixel size than the first image data including the out-of-field area. Therefore, in order to perform three-dimensional reconstruction processing on the second image data supplemented with the image data of the out-of-field region, the out-of-field region in the first image data is adjusted to the pixel size of the second image data. Split and convert.

For example, a case where 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 will be described. In this case, the processing function 173 multiplies the number of pixels on one side of the first image data to be matrix-converted by (α/β) to convert the number of pixels. Here, the image data to be matrix-transformed may be not only the out-of-field area in the first image data, but also an area extended in the x-axis direction wider than the out-of-field area in the first image data.

The processing function 173 transforms the pixel levels in the out-of-view region so as to match the pixel levels of the first image data and the second image data. Specifically, the processing function 173 converts (gain conversion) the pixel level of the matrix-converted image data including the out-of-field area in the first image data into the pixel level of the second image data. By performing this gain conversion, each detector outputs transmitted X-rays collected by the first detector and the second detector through the same path with the same gain. Accordingly, three-dimensional reconstruction processing can be performed on the gain-converted image data under the same reconstruction conditions as for the second image data. Here, the image data for gain conversion conforms to the image data for matrix conversion, but when the image data for matrix conversion includes other regions in addition to the out-of-view region, may be subject to gain conversion.

The processing function 173 supplements the second image data for each rotation angle using the information of the out-of-view area (out-of-view area information) in the first image data. Specifically, the processing function 173 generates synthesized data by synthesizing the image data of the outside-of-field region of the first image data on which matrix conversion and gain conversion have been performed with the second image data. In FIG. 4, the composite data is image data that combines the second image and the out-of-view region.

The processing function 173 transmits synthesized data to the medical image processing apparatus 2 via the network 3 . A reconstruction function 211 in the medical image processing apparatus 2 reconstructs three-dimensional image data using the synthesized data received from the X-ray diagnostic apparatus 1 . Here, the technique of reconstruction processing may be performed by a known method. For example, filtered back projection (FBP), iterative reconstruction, and the like can be used.

Next, a procedure of processing by the X-ray diagnostic apparatus 1 will be described. FIG. 5 is a flow chart showing the procedure of processing by the X-ray diagnostic apparatus 1 according to the first embodiment. Step S101 in FIG. 5 is implemented by processing circuit 17 reading out a program corresponding to acquisition function 172 from storage circuit 24 and executing the program. Steps S102 to S105 are implemented by processing circuit 17 reading out a program corresponding to processing function 173 from storage circuit 24 and executing the program. Further, step S106 is realized by the processing circuit 21 in the medical image processing apparatus 2 reading out a program corresponding to the reconstruction function 211 from a storage circuit (not shown) of the medical image processing apparatus 2 and executing the program.

As shown in FIG. 5, processing circuitry 17 collects image data (step S101) and determines an out-of-field region (step S102). Then, the processing circuit 17 performs pixel size conversion on the first image data (step S103), and performs pixel level conversion (step S104). Next, the processing circuit 17 supplements the second image data using the out-of-view area information (step S105). The processing circuit 21 then executes three-dimensional reconstruction (step S106). Here, the order of the steps described in the flowchart of FIG. 5 is an example, and the order of each step may be changed.

As described above, according to the first embodiment, the X-ray detector 15 shares the scintillator 15c for converting the X-rays emitted from the X-ray tube 12 into light, and the light converted by the scintillator 15c. and a second photodetector 15b having a smaller field of view than the first photodetector 15a. The acquisition function 172 rotates the X-ray detector 15 around the subject P by the C-arm 16 that supports the X-ray detector 15, and sequentially acquires signals based on detection signals output by the first photodetector 15a. The obtained first image data and the second image data sequentially collected based on the detection signal output from the second photodetector 15b are acquired. The processing function 173 processes the second image data for each rotation angle of the X-ray detector 15 using outside-of-field area information, which is information on an image area other than the area of the second image data in the first image data. make up for it. 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 three-dimensional reconstruction is performed. Therefore, it is possible to generate a three-dimensional image with high accuracy. As a result, the operator can perform the procedure more accurately and safely by referring to the accurate three-dimensional image.

Further, according to the first embodiment, the processing function 173 converts the pixel size of the out-of-view area information according to the pixel size of the second image data, and uses the converted out-of-view area information to perform Supplement the second image data. As a result, the synthesized data, which is the second image data supplemented with the converted out-of-view area information, has a uniform pixel size. Therefore, the X-ray diagnostic apparatus 1 can uniformly perform three-dimensional reconstruction on two types of image data collected by different detectors and having different resolutions, so that three-dimensional images can be generated with high accuracy. to

Further, according to the first embodiment, the processing function 173 converts the pixel level in the out-of-view area information so as to match the pixel level of the first image data and the pixel level of the second image data. , supplements the second image data using the converted out-of-view area information. As a result, the combined data, which is the second image data supplemented by the converted outside-of-view area information, is matched in pixel level. Therefore, the X-ray diagnostic apparatus 1 can uniformly perform three-dimensional reconstruction of synthesized data by matching the output levels of transmitted X-rays collected by different detectors, so that three-dimensional images can be generated with high accuracy. enable

Also, according to the first embodiment, the second photodetector 15b has a higher resolution than the first photodetector 15a. This allows the X-ray diagnostic apparatus 1 to generate a high-definition three-dimensional image. For example, when observing minute blood vessels running around an aneurysm in the treatment of a cerebral aneurysm, the X-ray diagnostic apparatus 1 can accurately depict minute-shaped parts.

Further, according to the first embodiment, the reconstruction function 211 reconstructs three-dimensional image data based on the second image data supplemented using the out-of-field area information. 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 three-dimensional reconstruction is performed. Therefore, it is possible to generate a three-dimensional image with high accuracy.

(Modification 1)
In the first embodiment described above, the case where the reconstruction function 211 of the medical image processing apparatus 2 reconstructs three-dimensional image data has been described. However, the embodiment is not limited to this, and a case where the three-dimensional reconstruction processing is executed by the X-ray diagnostic apparatus 1 may also be used. In such a case, a program that functions the reconstruction function 211 and is stored in the storage circuit of the medical image processing apparatus 2 is stored in the storage circuit 20 of the X-ray diagnostic apparatus 1 . Then, the processing circuit 17 reads out a program corresponding to the reconstruction function 211 from the storage circuit 20 and executes the same processing as the reconstruction function 211 . Specifically, the processing circuit 17 reconstructs three-dimensional image data using the generated synthesized data.

(Second embodiment)
In the first embodiment, 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 and the coordinate center of the second photodetector 15b match. , the case where synthetic data is generated based on the out-of-view area information. In the second embodiment, processing by the X-ray diagnostic apparatus 1 when there is a deviation between the coordinate center of the first photodetector 15a and the coordinate center of the second photodetector 15b will be described. Specifically, in the second embodiment, a case will be described in which image data is collected from the X-ray detector 15, positional deviation is corrected, and synthetic data is generated based on the corrected outside-of-view area information. .

FIG. 6 is a block diagram showing an example of the configuration of the X-ray diagnostic apparatus 1 according to the second embodiment. The X-ray diagnostic apparatus 1 according to the second embodiment differs from the X-ray diagnostic apparatus 1 according to the first embodiment in that the processing circuit 17 further executes a calibration function 174 . The following description focuses on differences from the first embodiment.

The processing function 173 supplements the second image data using the information of 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 detects the positional deviation between the first image data and the second image data caused by the positional deviation between the first photodetector 15a and the second photodetector 15b. Synthetic data is generated using the corrected out-of-field area information.

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

First, correction of misalignment using information about misalignment between photodetectors will be described. The processing function 173 uses the first image data and the second image data whose positional relationship is corrected based on the information about the positional deviation between the first photodetector 15a and the second photodetector 15b. to calculate the out-of-view area information. Specifically, the processing function 173 calculates information (position correction information) regarding the positional deviation occurring 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 deviations. The first is the positional deviation of the central coordinates (center) of each photodetector. The second is a shift in the rotational axis direction of the photodetectors that occurs when one photodetector rotates with respect to the other photodetector. Then, based on the calculated position correction information, the processing function 173 changes the position (pixel shift) of the first image data with respect to the second image data to correct the positional deviation.

The position correction information described above is calculated, for example, by X-ray imaging using a phantom. In a scene such as calibration performed before imaging the subject P, the X-ray diagnostic apparatus 1 performs X-ray imaging with a phantom as an irradiation target, and merges the first image data and the second image data into one. Collect one by one. The processing function 173 uses the image data collected one by one with the phantom as the irradiation target, and calculates the x-axis and y-axis of one image data and the other image data in the first image data and the second image data. A directional positional deviation amount (X, Y) and a rotation angle φ are calculated. Here, the position correction information in this embodiment is expressed as (X, Y, φ). The processing function 173 stores the calculated position correction information (X, Y, φ) in the storage circuit 20 .

After that, the processing function 173 treats the first image data and the second image data, which are acquired by the acquisition function 172 and consist of a plurality of images, as the subject of the subject P, and corrects them based on the position correction information. Execute the process. For example, the processing function 173 shifts (pixel shifts) one of the first image data and the second image data with respect to the other image data based on the position correction information, thereby obtaining the first image data. positional deviation between the first image data and the second image data. Here, the processing function 173 uniformly performs the pixel shift described above on the image data collected for each rotation angle θ of the X-ray detector 15 . As a result, the processing function 173 can correct the misalignment between the image data caused by the misalignment between the photodetectors.

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

Next, correction of misregistration using misregistration information between image data will be described. The processing function 173 outputs the first image data and the second image data whose positional relationship is corrected for each rotation angle based on the information about the positional deviation between the first image data and the second image data for each rotation angle. Out-of-view area information is calculated using the image data. Specifically, the processing function 173 calculates information about the positional deviation between the pair of the first image data and the second image data having the same rotation angle obtained by rotational imaging. The information about the positional deviation is information obtained by collecting the above-described positional correction information (X, Y, φ) for each rotation angle θ of the detector in rotation imaging. Then, the processing function 173 performs pixel shift on the pair of the first image data and the second image data corresponding to the rotation angle θ based on the calculated position correction information. As a result, the processing function 173 can correct the misalignment even if misalignment occurs between the photodetectors during rotational imaging.

For example, the processing function 173 uses the first image data and the second image data obtained by rotationally imaging the subject P to obtain position correction information (X, Y, φ) for each rotation angle θ. calculate. Here, the position correction information is, for example, detected by image processing of the subject P or an object (such as a device) drawn in common in a pair of image data corresponding to a certain rotation angle θ, and the positional relationship of the detected object. calculated from However, the image processing may be performed by a known method. Then, based on the calculated position correction information, the processing function 173 shifts the pixels of one of the first image data and the second image data with respect to the other image data for each frame. As a result, the processing function 173 can correct the misalignment between the image data caused by the misalignment between the photodetectors during rotational imaging.

In addition, although the above-described case has been described in which the positional deviation information between the image data is calculated based on the image data acquired by rotationally photographing the subject P, the embodiment is not limited to this. For example, position correction information may be calculated using previously collected image data based on rotational photography. This is because if it is expected that the positional deviation between the photodetectors for each rotation angle .theta. has also occurred in the past rotational imaging, the positional correction information is considered to be common. Therefore, the processing function 173 may correct the positional deviation between the image data using previously calculated positional correction information without newly calculating the positional correction information each time rotation shooting is performed. Here, the object related to rotational photography acquired in the past may be the same as the object P related to the target image data to be subjected to the positional deviation correction, or may be another object.

Further, the positional deviation correction using the positional deviation information between the image data described above can be used to create three-dimensional calibration data related to rotational imaging. For example, as one maintenance of the X-ray diagnostic apparatus 1, three-dimensional calibration is performed for each of the first detector and the second detector to create three-dimensional calibration data for each detector. Here, the three-dimensional calibration data referred to in the present embodiment refers to each of the transmitted X-rays emitted from the X-ray tube and transmitted through the irradiation target for each rotation angle θ, which pixel electrode ( cell) collected. For example, the three-dimensional calibration data indicates the correspondence relationship between the rotation angle and the coordinate data representing the irradiation target on the XY plane on which the X-rays of the detector are incident. Three-dimensional calibration uses three-dimensional calibration data so that transmitted X-rays can be collected without changing the correspondence between the X-ray focal point and the cell of the X-ray detector 15 during rotational imaging. can be corrected. However, since the X-ray detector 15 has two different photodetectors, three-dimensional calibration is performed twice, and it takes time to collect the three-dimensional calibration data.

Therefore, the calibration function 174 uses the positional relationship between the first photodetector 15a and the second photodetector 15b and the calibration data (first calibration data) of the first photodetector 15a. to generate calibration data (second calibration data) for the second photodetector 15b. Here, the positional relationship between the first photodetector 15a and the second photodetector 15b is determined for each rotation angle θ using the first image data and the second image data obtained by rotational imaging. is the position correction information (X, Y, φ) calculated in . For example, the calibration function 174 creates second calibration data using the position correction information described above and the first calibration data created based on the first image data.

For example, the position correction information and the first calibration data are obtained by rotating and photographing the phantom as an irradiation target. When rotational imaging is performed, the acquisition function 172 acquires the first image data and the second image data. Then, the processing function 173 calculates position correction information using the acquired image data. A calibration function 174 creates first calibration data based on the first image data. Then, the calibration function 174 corrects the first calibration data based on the position correction information using the fact that the calculated position correction information indicates the positional relationship between the photodetectors, thereby performing the second calibration. Create data.

The calibration data for the first photodetector 15a may be created using the position correction information and the calibration data for the second photodetector 15b. Specifically, the calibration function 174 uses the positional relationship between the first photodetector 15a and the second photodetector 15b and the calibration data of the second photodetector 15b to obtain the first Generate calibration data for the 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. A calibration function 174 creates second calibration data based on the second image data. Then, the calibration function 174 corrects the calibration data of the second photodetector 15b based on the positional correction information by using the fact that the calculated positional correction information indicates the positional relationship between the photodetectors. , to create calibration data for the first photodetector 15a.

(Modification 1)
Further, the reconstruction processing of three-dimensional image data in the above-described second embodiment is not limited to the medical image processing apparatus 2 as in the first modification of the first embodiment, but is executed by the X-ray diagnostic apparatus 1. may In such a case, the processing circuit 17 reconstructs three-dimensional image data using the generated synthetic data.

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

As shown in FIG. 7, processing circuitry 17 collects image data (step S201) and determines an out-of-view region (step S202). Then, the processing circuit 17 corrects the positional relationship (step S203). Further, the processing circuit 17 performs pixel size conversion on 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-view area information (step S206). The processing circuitry 21 then executes three-dimensional reconstruction (step S207). Here, the order of the steps described in the flowchart of FIG. 7 is an example, and the order of each step may be changed. For example, positional relationship correction (step S203) may be performed after image data acquisition (step S201) and before three-dimensional reconstruction (step S207).

As described above, according to the second embodiment, the processing function 173 uses the out-of-field area information calculated according to the positional relationship between the first photodetector 15a and the second photodetector 15b to 2 image data is supplemented. Thereby, the positional relationship of the image data derived from the positional relationship between the photodetectors can be calculated. Then, by calculating the out-of-view area information based on the calculated positional relationship, it is possible to accurately generate synthesized data supplemented with the second image data. As a result, it is possible to generate a three-dimensional image with high accuracy.

Further, according to the second embodiment, the processing function 173 uses the first photodetector 15a and the second photodetector 15b whose positional relationship is corrected based on the information about the positional deviation between the first photodetector 15a and the second photodetector 15b. Out-of-view area information is calculated using the image data and the second image data. Thereby, it is possible to correct the positional deviation between the image data caused by the positional deviation between the photodetectors. Further, since the out-of-field area information can be calculated based on the corrected image data and the synthesized data can be generated with higher accuracy by supplementing the second image data, it is possible to generate a three-dimensional image with high accuracy.

Further, according to the second embodiment, the processing function 173 corrects the positional relationship for each rotation angle based on the information regarding the positional deviation between the first image data and the second image data for each rotation angle. Further, out-of-view area information is calculated using the first image data and the second image data. Thereby, it is 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 imaging. Further, since the out-of-field area information can be calculated based on the corrected image data and the synthesized data can be generated with higher accuracy by supplementing the second image data, it is possible to generate a three-dimensional image with high accuracy.

Further, according to the second embodiment, the calibration function 174 determines the positional relationship between the first photodetector 15a and the second photodetector 15b and the calibration data of the first photodetector 15a. is used to generate calibration data for the second photodetector 15b. Thereby, calibration data can be created based on the positional relationship between the photodetectors. Then, by calculating the out-of-view area information based on the calculated positional relationship, it is possible to easily generate synthesized data in which the second image data is accurately supplemented.

Further, according to the second embodiment, the calibration function 174 determines the positional relationship between the first photodetector 15a and the second photodetector 15b and the calibration data of the second photodetector 15b. is used to generate calibration data for the first photodetector 15a. Thereby, calibration data can be created based on the positional relationship between the photodetectors. Then, by calculating the out-of-view area information based on the calculated positional relationship, it is possible to easily generate synthesized data in which the second image data is accurately supplemented.

(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 embodiment is not limited to this, and the medical image processing apparatus 2 may perform the image processing according to the present application. FIG. 8 is a block diagram showing an example configuration of a medical image processing apparatus 2 according to another embodiment. The medical image processing device 2 is, for example, a server device, a workstation, a viewer, a tablet, a PC (Personal Computer), or the like. As shown in FIG. 8 , the medical image processing apparatus 2 is connected to the X-ray diagnostic apparatus 1 via a network 3 .

The medical image processing apparatus 2 performs image processing on each image data acquired by the X-ray diagnostic apparatus 1 according to user's operation. The medical image processing apparatus 2 has a processing circuit 21 , an input interface 22 , a display 23 , a memory circuit 24 and a communication interface 25 . Here, the input interface 22, the display 23, and the memory circuit 24 are the same as those of the X-ray diagnostic apparatus 1 according to the first and second embodiments, so the description thereof is omitted. The processing circuitry 21 according to other embodiments differs from the first and second embodiments in that it performs an acquisition function 212, a processing function 213, and a calibration function 214. FIG. Acquisition function 212 controls communication interface 25 and collects image data via network 3 . The processing function 213 executes processing similar to that of the processing function 173 described in the first and second embodiments. Also, the calibration function 214 executes the same processing as the calibration function 174 described in the second embodiment. Note that the reconstruction function 211 according to other embodiments executes processing similar to the processing described in the first and second embodiments.

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

Further, the correction of the image data resulting from the misalignment between the photodetectors described above and the creation of the calibration data may be performed in the medical image processing apparatus 2, and the medical image processing apparatus 2 instructs to perform the X-ray detection. Diagnosis device 1 may perform. That is, when the medical image processing apparatus 2 performs image processing according to the present application on image data, a part of the processing may be performed by a corresponding function within the X-ray diagnostic apparatus 1 .

In addition, the term "processor" used in the description of the above embodiments is, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or an application specific integrated circuit (ASIC), Circuits such as programmable logic devices (e.g., Simple Programmable Logic Devices (SPLDs), Complex Programmable Logic Devices (CPLDs), and Field Programmable Gate Arrays (FPGAs)) means. Here, instead of storing the program in the memory circuit 20, the program may be configured to be directly installed in the circuit of the processor. In this case, the processor implements its functions by reading and executing the program embedded in the circuit. Further, each processor of 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 its function. good.

Here, the program executed by the processor is pre-installed in a ROM (Read Only Memory), a storage circuit, or the like and provided. This program is a file in a format that can be installed in these devices or in a format that can be executed, such as CD (Compact Disk)-ROM, FD (Flexible Disk), CD-R (Recordable), DVD (Digital Versatile Disk), etc. may be recorded and provided on a non-transitory computer-readable storage medium. Also, this program may 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, this program is composed of modules including each processing function described above. As actual hardware, the CPU reads out a program from a storage medium such as a ROM and executes it, so that each module is loaded onto the main storage device and generated on the main storage device.

In addition, in the above-described embodiments and modifications, each component of each device illustrated is functionally conceptual, and does not necessarily need to be physically configured as illustrated. That is, the specific form of distribution or integration of each device is not limited to the illustrated one, and all or part of them can be functionally or physically distributed or distributed in arbitrary units according to various loads, usage conditions, etc. Can be integrated and configured. Furthermore, each processing function performed by each device may be implemented in whole or in part by a CPU and a program analyzed and executed by the CPU, or implemented as hardware based on wired logic.

Further, among the processes described in the above-described embodiment and modifications, all or part of the processes described as being automatically performed can be manually performed, or can be manually performed. All or part of the described processing can also be performed automatically by known methods. In addition, information including processing procedures, control procedures, specific names, and various data and parameters shown in the above documents and drawings can be arbitrarily changed unless otherwise specified.

According to at least one embodiment described above, it is possible to accurately generate a three-dimensional image.

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

1 X-ray diagnostic apparatus 2 Medical image processing apparatus 15 X-ray detector 16 C-arm 172, 212 Acquisition function 173, 213 Processing function 174, 214 Calibration function 211 Reconstruction function

Claims (14)

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 according to the light converted by the scintillator; an X-ray detector having a second photodetector with a smaller field of view than the photodetector;
The X-ray detector is rotated around the subject by an arm supporting the X-ray detector, and first image data is sequentially collected based on detection signals output from the first photodetector; an acquisition unit for acquiring second image data sequentially acquired based on the detection signal output by the second photodetector;
For each rotation angle of the X-ray detector, the second image data is supplemented using out-of-field area information, which is information on an image area other than the area of the second image data in the first image data. a processing unit;
An X-ray diagnostic apparatus comprising: The processing unit converts the pixel size of the out-of-view area information according to the pixel size of the second image data, and uses the converted out-of-view area information to supplement the second image data. The X-ray diagnostic apparatus according to claim 1. The processing unit converts the pixel level in the out-of-view area information so as to match the pixel level of the first image data and the pixel level of the second image data, and converts the out-of-view area after conversion. 3. The X-ray diagnostic apparatus according to claim 1, wherein information is used to supplement said second image data. The processing unit supplements the second image data using the out-of-field area information calculated according to the positional relationship between the first photodetector and the second photodetector. 4. The X-ray diagnostic apparatus according to any one of 1 to 3. The processing unit generates the first image data and the second image data, the positional relationship of which is corrected based on information about the positional deviation between the first photodetector and the second photodetector. 5. The X-ray diagnostic apparatus according to claim 4, wherein said out-of-field region information is calculated using . The processing unit generates the first image, the positional relationship of which is 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. 5. The X-ray diagnostic apparatus according to claim 4, wherein the out-of-field area information is calculated using the data and the second image data. generating calibration data for the second photodetector using the positional relationship between the first photodetector and the second photodetector and the calibration data for the first photodetector; 7. The X-ray diagnostic apparatus according to any one of claims 4 to 6, further comprising a calibrating unit. generating calibration data for the first photodetector using the positional relationship between the first photodetector and the second photodetector and calibration data for the second photodetector; 7. The X-ray diagnostic apparatus according to any one of claims 4 to 6, further comprising a calibrating unit. The X-ray diagnostic apparatus according to any one of claims 1 to 8, wherein said second photodetector has higher resolution than said first photodetector. The X-ray diagnosis according to any one of claims 1 to 9, further comprising a reconstructing unit that reconstructs three-dimensional image data based on the second image data supplemented using the out-of-field region information. Device. 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 according to the light converted by the scintillator; and a second photodetector having a smaller field of view than the photodetector, wherein an arm supporting the X-ray detector urges the X-ray detector to the subject. and sequentially collected based on the detection signal output by the first photodetector and sequentially based on the detection signal output by the second photodetector an acquisition unit that acquires the collected second image data;
For each rotation angle of the X-ray detector, the second image data is supplemented using out-of-field area information, which is information on an image area other than the area of the second image data in the first image data. a processing unit;
A medical image processing apparatus comprising: 12. The medical image processing apparatus according to claim 11, further comprising a reconstruction unit that reconstructs three-dimensional image data based on the second image data supplemented using the out-of-field area information. to the computer,
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 according to the light converted by the scintillator; and a second photodetector having a smaller field of view than the photodetector, wherein an arm supporting the X-ray detector urges the X-ray detector to the subject. and sequentially collected based on the detection signal output by the first photodetector and sequentially based on the detection signal output by the second photodetector an acquisition function for acquiring collected second image data, and for each rotation angle of the X-ray detector, the second image data is acquired from the area of the second image data in the first image data Processing function to compensate using out-of-view area information, which is information on image areas other than
A program that realizes to the computer;
14. The program according to claim 13, further realizing a reconstruction function of reconstructing three-dimensional image data based on the second image data supplemented using the out-of-field area information.

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