JP7691306B2 - X-ray diagnostic equipment and medical image processing equipment. - Google Patents

Description

The embodiments disclosed in this specification and the drawings relate to X-ray diagnostic devices and medical image processing devices.

Conventionally, in examinations using X-ray diagnostic devices, a narrow region of interest may be observed at high resolution. For this reason, X-ray diagnostic devices are known that are equipped with a first detector with a large field of view that employs a TFT (Thin Film Transistor) array, and a second detector that uses a CMOS (Complementary Metal Oxide Semiconductor) and has a smaller field of view than the first detector, a finer pixel pitch, and high resolution.

In this type of X-ray diagnostic device, X-rays are detected simultaneously by the first detector and the second detector, and a first image generated from the X-ray signal output by the first detector and a second image generated from the X-ray signal output by the second detector can be simultaneously displayed (hereinafter referred to as high-resolution simultaneous display).

However, because the second detector has a small field of view, if there is a misalignment between the two second images generated from the electrical signals output by the second detector at two different times, it is difficult to align the two second images.

JP 2018-149229 A

One of the problems that the embodiments disclosed in this specification and the drawings attempt to solve is to align the small field of view image based on the second detector with high precision when X-rays are detected simultaneously by the first detector and the second detector. However, the problems that the embodiments disclosed in this specification and the drawings attempt to solve are not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described below can also be positioned as other problems.

The X-ray diagnostic apparatus according to the embodiment includes an X-ray detector and a correction unit. The X-ray detector includes a scintillator that converts X-rays emitted from an X-ray tube into light, and a first detector and a second detector that share the scintillator, simultaneously detect the light converted by the scintillator, and output electrical signals, and have a smaller field of view and higher resolution than the first detector. The correction unit corrects positional deviation in a second image generated from the electrical signal output by the second detector, using a first image generated from the electrical signal output by the first detector.

1 is a block diagram showing an example of the configuration of an X-ray diagnostic apparatus including an image processing apparatus according to an embodiment. FIG. 2 is a block diagram showing an example of the arrangement of an FPD according to the present embodiment. FIG. 13 is a diagram for explaining conventional alignment of a second image. FIG. 13 is another diagram for explaining the conventional alignment of the second image. A flowchart showing an example of a procedure for correcting the positional shift of a small field of view image generated from an electrical signal output by a second detector using a large field of view image generated from an electrical signal output by a first detector when high-resolution simultaneous display is performed by a processor of the processing circuit shown in Figure 1. FIG. 11 is a diagram for explaining a method for correcting a positional deviation of a small-field-of-view image by using a large-field-of-view image. 1A is an explanatory diagram showing an example of a method for removing the influence of an ROI filter, and FIG. 1B is an explanatory diagram showing another example. 11A and 11B are diagrams for explaining a first modified example of a method for calculating a pixel shift value PS_S of a small field of view image. 13A and 13B are diagrams for explaining a second modified example of the method for calculating a pixel shift value PS_S of a small field of view image. 13A to 13C are diagrams for explaining a third modified example of the method for calculating a pixel shift value PS_S of a small field of view image. 13 is a diagram for explaining a fourth modified example of the method for calculating a pixel shift value PS_S of a small field of view image. FIG. 13 is a diagram for explaining a fifth modified example of the method for calculating a pixel shift value PS_S of a small field of view image.

Below, embodiments of an X-ray diagnostic apparatus and a medical image processing apparatus will be described in detail with reference to the drawings. In the following description, a device refers to a treatment device inserted into a subject, such as a catheter or a guidewire.

FIG. 1 is a block diagram showing an example of the configuration of an X-ray diagnostic device 10 including an image processing device according to an embodiment. The X-ray diagnostic device 10 may be any device capable of capturing multiple frames of images in succession, and may include, for example, an X-ray TV device or an X-ray angiography device.

As shown in FIG. 1, the X-ray diagnostic device 10 has an imaging device 20 and a console 30 as an example of a medical image processing device.

The imaging device 20 is typically installed in an examination room and configured to generate image data related to the subject. The console 30, which is an example of a medical image processing device, is installed, for example, in an operation room adjacent to the examination room and generates and displays X-ray images based on the image data. The console 30 may be installed in the examination room where the imaging device 20 is installed, or may be connected to the imaging device 20 via a network and installed in a remote location away from the examination room.

The imaging device 20 has an X-ray tube 21, an X-ray movable aperture 22, a region of interest filter (hereinafter referred to as ROI filter) 23, an FPD 24, a tabletop 25, a high-voltage power supply 26, an aperture driver 27, and a controller 29.

The X-ray tube 21 generates X-rays when a voltage is applied from the high-voltage power supply 26.

The X-ray movable aperture 22 is a lead plate or the like for narrowing the irradiation range of the X-rays generated by the X-ray tube 21, and a slit is formed by combining multiple lead plates or the like. For example, the X-ray movable aperture 22 has two pairs of movable blades, and is controlled by the controller 29 via the aperture drive device 27, and the irradiation range of the X-rays irradiated from the X-ray tube 21 is adjusted by opening and closing each pair of movable blades.

The ROI filter 23 is composed of a flat plate of copper, aluminum, or the like, with an X-ray aperture provided in a portion of it. X-rays pass through the X-ray aperture unattenuated, while X-rays are attenuated by the ROI filter 23 and transmitted through areas other than the X-ray aperture. The shape of the X-ray aperture may be, for example, a rectangle with a side measuring several mm to several tens of mm, or it may be a circle, an ellipse, or a polygon other than a rectangle. The ROI filter 23 is controlled by the controller 29 via the aperture driver 27, and the position of the X-ray aperture can be translated.

The FPD 24 is composed of a flat panel detector (FPD: Flat Panel Detector) having multiple X-ray detection elements (group of imaging elements), detects X-rays irradiated to the FPD 24, and outputs image data of X-ray fluoroscopic images and X-ray radiographic images (hereinafter, X-ray fluoroscopic images and X-ray radiographic images are collectively referred to as X-ray images) at a predetermined frame rate based on the detected X-rays. This image data is provided to the console 30. More specifically, the FPD 24 has multiple X-ray detection elements composed of semiconductor elements that accumulate signal charges according to the amount of incident X-rays. The multiple X-ray detection elements are arranged in a matrix.

Figure 2 is a block diagram showing an example of the configuration of the FPD 24 according to this embodiment.

For example, as shown in FIG. 2, the FPD 24 has a first detector 24a, a second detector 24b, and a scintillator 24c. The first detector 24a and the scintillator 24c form a first FPD 24d with a large field of view, and the second detector 24b and the scintillator 24c form a second FPD 24e with a small field of view.

The scintillator 24c converts the X-rays emitted from the X-ray tube 21 into light. The first detector 24a includes, for example, a two-dimensional image sensor that employs a TFT (Thin Film Transistor) array made of amorphous silicon, and detects the light converted by the scintillator 24c and outputs an electrical signal. The second detector 24b includes, for example, a two-dimensional image sensor that employs a CMOS (Complementary Metal Oxide Semiconductor) transistor, and detects the light converted by the scintillator 24c and outputs an electrical signal. The electrical signal output by the first detector 24a and the second detector 24b is also called an X-ray signal.

In this way, the scintillator 24c is shared by the first detector 24a and the second detector 24b. In other words, the FPD 24 has a scintillator 24c that converts the X-rays irradiated from the X-ray tube 21 into light, and the first detector 24a and the second detector 24b that share the scintillator 24c, detect the light converted by the scintillator 24c, and output an electrical signal. The first detector 24a and the second detector 24b each output an electrical signal that simultaneously detects the light converted by the scintillator 24c.

As shown in FIG. 2, the first detector 24a and the second detector 24b each have a plurality of element portions that are the constituent units of pixels. Each of these element portions converts a fluorescent image obtained by the incidence of X-rays into an electrical signal and accumulates it in a photodiode (PD: Photo Diode). In the example shown in FIG. 2, the first detector 24a has eight element portions, and the second detector 24b has eight element portions.

Here, the pixel pitch of each element part of the second detector 24b is finer than the pixel pitch of each element part of the first detector 24a. In the example shown in FIG. 2, the pixel pitch of each element part of the first detector 24a corresponds to the pixel pitch of two element parts of the second detector 24b. In other words, the second detector 24b has a higher resolution than the first detector 24a. Also, as shown in FIG. 2, the first detector 24a has a wider field of view size than the second detector 24b.

In general, X-ray fluoroscopy acquires images with a weaker X-ray irradiation intensity than X-ray imaging. Therefore, although X-ray fluoroscopy images have a lower resolution, the subject is exposed to a smaller amount of radiation. The X-ray diagnostic device 10 according to this embodiment is capable of performing both X-ray fluoroscopy and X-ray imaging (hereinafter collectively referred to as imaging).

The X-ray tube 21 and the FPD 24 may be disposed opposite each other with the subject placed on the tabletop 25 in between. For example, the X-ray tube 21 and the FPD 24 may be supported at both ends of the C-arm so as to be disposed opposite each other with the subject in between. The X-ray tube 21 and the FPD 24 may also be supported by independent support members.

The top plate 25 is provided on the top of the bed and is used to place the subject on it. The high-voltage power supply 26 has a high-voltage generator that generates a high voltage to be applied to the X-ray tube 21, and an X-ray control device that controls the output voltage according to the X-rays emitted by the X-ray tube 21. The high-voltage generator may be of a transformer type or an inverter type.

The controller 29 has at least a processor and a memory circuit. The controller 29 is controlled by the console 30 according to a program stored in the memory circuit, and controls each component of the imaging device 20. For example, the controller 29 is controlled by the console 30 to capture images of the subject at a predetermined frame rate, generate image data, and provide the image data to the console 30.

On the other hand, the console 30 has a display 31, an input interface 32, a memory circuit 33, and a processing circuit 34.

The display 31 is configured with a general display output device such as a liquid crystal display or an OLED (Organic Light Emitting Diode) display, and displays various information such as a composite image generated by the processing circuit 34 according to the control of the processing circuit 34.

The input interface 32 is realized by a general input device such as a trackball, a switch, a button, a mouse, a keyboard, a touchpad that performs input operations by touching the operation surface, a non-contact input interface using an optical sensor, and a voice input interface, and outputs an operation input signal corresponding to a user's operation to the processing circuit 34. The input interface 32 may also include an exposure switch that controls the on/off of exposure.

The memory circuit 33 has a configuration including a processor-readable recording medium, such as a magnetic or optical recording medium or a semiconductor memory. Some or all of the programs and data in the storage medium of the memory circuit 33 may be downloaded by communication via an electronic network, or may be provided to the memory circuit 33 via a portable storage medium such as an optical disk.

The processing circuitry 34 realizes the function of controlling the X-ray diagnostic device 10. In addition, the processing circuitry 34 reads and executes an image processing program stored in the memory circuitry 33, thereby aligning the small field of view image based on the second detector 24b with high accuracy when the first detector 24a and the second detector 24b simultaneously detect X-rays.

It is a processor that performs the processing for

As shown in FIG. 1, the processor of the processing circuitry 34 realizes an imaging control function 341, an acquisition function 342, an image generation function 343, and a correction function 344. Each of these functions is stored in the memory circuitry 33 in the form of a program. Note that some of the functions 314-344 of the processing circuitry 34 may be realized by an external processor connected to the console 30 via a network so as to be able to send and receive data.

The imaging control function 341 controls the imaging device 20 to control X-ray imaging of the subject at a predetermined frame rate.

The acquisition function 342 acquires output signals from each of the first detector 24a and the second detector 24b.

The image generation function 343 generates an X-ray image based on the output signal of the FPD 24. For example, the image generation function 343 generates a first image from the electrical signal output by the first detector 24a, and generates a second image from the electrical signal output by the second detector 24b.

The correction function 344 corrects the positional deviation of the second image generated from the electrical signal output by the second detector 24b by using the first image generated from the electrical signal output by the first detector 24a. Specifically, the correction function 344 obtains pixel shift values of the two first images generated from the electrical signal output by the first detector 24a at two different times, converts the pixel shift values based on the field of view ratio of the first detector 24a and the second detector 24b, and uses the converted pixel shift values to align the two second images generated from the electrical signal output by the second detector 24b at two different times.

Figure 3 is a diagram for explaining conventional alignment of the second image, and Figure 4 is another diagram for explaining conventional alignment of the second image.

In general, when subtracting a mask image from a live contrast image to display the image, the amount of positional deviation due to body movement, etc. is calculated between the mask image and the contrast image using image processing, and subtraction is performed in a pixel-shifted state, thereby reducing misregistration due to deviation.

Incidentally, when a first image generated from the X-ray signal output by the first detector 24a and a second image generated from the X-ray signal output by the second detector 24b are displayed simultaneously (high-resolution simultaneous display), images with different field of view sizes are displayed simultaneously, allowing the user to check the detailed situation in a narrow range while also displaying a fluoroscopic image with a large field of view, making it easier to grasp the overall picture.

However, it may be difficult to correct misalignment in a second image with a small field of view and high resolution.

One of the reasons that makes it difficult to correct the position shift is that there are few feature points such as bone contours within the field of view of the second image. As shown in FIG. 3, the large-field-of-view mask image 42 corresponding to the large field of view 41 of the first detector 24a when the mask image is acquired, and the large-field-of-view live image 44 corresponding to the large field of view 43 of the first detector 24a when the live image is acquired contain a position shift caused by the subject's body movement according to the time difference between the imaging timings of the two images. Both the large-field-of-view mask image 42 and the large-field-of-view live image 44 have a large field of view, and therefore contain many feature points such as edges for image processing. Therefore, the pixel shift value can be easily and accurately determined from the large-field-of-view mask image 42 and the large-field-of-view live image 44.

On the other hand, the small-field-of-view mask image 52 and the small-field-of-view live image 54 have a small field of view and therefore contain few feature points. Furthermore, in a small-field-of-view image, the bone contours are not considered important for the user to check the image and are often located at the edge of the image, while the edges of the screen are excluded from image processing. For this reason, it is difficult to accurately determine the pixel shift value from the small-field-of-view mask image 52 and the small-field-of-view live image 54.

Another reason that makes it difficult to correct the positional shift is that the proportion of the device, such as a catheter, is larger than the feature points, such as bone contours, contained in the field of view of the second image, and the device is moving. As shown in FIG. 4, the proportion of the device 61 may be higher in the small field of view live image 54 than in the large field of view live image 44. In this case, it is difficult to accurately determine the pixel shift value from the small field of view mask image 52 and the small field of view live image 54 due to the influence of the device movement.

The processing circuit 34 according to this embodiment therefore aligns the second image with high precision when simultaneously displaying high resolution images by correcting the positional shift of the second image generated from the electrical signal output by the second detector 24b using the first image generated from the electrical signal output by the first detector 24a.

Figure 5 is a flowchart showing an example of a procedure for correcting the positional shift of a small field of view image generated from an electrical signal output by the second detector 24b using a large field of view image generated from an electrical signal output by the first detector 24a when simultaneously displaying high resolution images by the processor of the processing circuit 34 shown in Figure 1. In Figure 5, the reference numbers with S followed by numbers indicate each step of the flowchart.

Figure 6 is an explanatory diagram showing a method for correcting the positional deviation of a small-field-of-view image using a large-field-of-view image.

First, in step S1, the acquisition function 342 acquires the output signals that are simultaneously detected and output by the first detector 24a and the second detector 24b.

Next, in step S2, the image generation function 343 generates a large field of view mask image 42 from the electrical signal output by the first detector 24a, and generates a small field of view mask image 52 from the electrical signal output by the second detector 24b.

Next, in step S3, the acquisition function 342 acquires the output signals detected and output simultaneously by each of the first detector 24a and the second detector 24b. The image generation function 343 generates a large field of view live image 44 from the electrical signal output by the first detector 24a, and generates a small field of view live image 54 from the electrical signal output by the second detector 24b.

Next, in step S4, the correction function 344 determines the pixel shift value PS_L between the large-field-of-view live image 44 and the large-field-of-view mask image 42 (see the upper right of Figure 6).

Next, in step S5, the correction function 344 converts the pixel shift value PS_L based on the field of view ratio between the first detector 24a and the second detector 24b to obtain the pixel shift value PS_S of the small field of view image (see the lower right of Figure 6).

Next, in step S6, the correction function 344 aligns the small-field live image 54 and the small-field mask image 52 using the pixel shift value PS_S of the small-field image. The image generation function 343 then generates a difference image between the aligned small-field live image 54 and the small-field mask image 52, and displays it on the display 31.

By following the above procedure, when high-resolution images are displayed simultaneously, the small-field-of-view image can be aligned with high precision by using the large-field-of-view image to correct the positional shift of the small-field-of-view image. By using the large-field-of-view image, the small-field-of-view image can be aligned with high precision compared to aligning the small-field-of-view image using only the small-field-of-view image.

For example, a fluoroscopy roadmap image in which a device image and a blood vessel image are combined may be used. When generating a device image for such a fluoroscopy roadmap image, a device mask image based on X-ray fluoroscopy may be used as the mask image, and a live image based on X-ray fluoroscopy may be used as the live image, and the difference image between these may be used as the device-extracted fluoroscopy image. In addition, when coiling a cerebral blood vessel aneurysm, a rendering image of volume data obtained by an X-ray CT device or X-ray diagnostic device may be used as the above-mentioned blood vessel image. In such a case, when an external image processing device is used, a pixel shift value PS_L may be provided to the image processing device, and the pixel shift value PS_S of the small field of view image may be converted in the image processing device to align the small field of view image.

In addition, when generating a DSA image, a mask image based on X-ray photography before contrast agent administration can be used as the mask image, and a live image based on X-ray photography after contrast agent administration can be used as the live image.

Figure 7 (a) is an explanatory diagram showing an example of a method for removing the influence of the ROI filter 23, and (b) is an explanatory diagram showing another example. When the ROI filter 23 is used, the range in which X-rays are irradiated onto the detector through the opening of the ROI filter 23 is often set to be the same as the field of view of the second detector 24b.

When using the ROI filter 23, the dose is different between the region 71 on the detector that corresponds to the opening of the ROI filter and other regions. Therefore, the correction function 344 may exclude the region 71 from the calculation when determining the pixel shift value PS_L between the large field of view live image 44 and the large field of view mask image 42 (see FIG. 7(a)).

In addition, the dose in boundary region 72 of region 71 may differ significantly from the dose in other regions due to the effects of scattered radiation and diffraction. For this reason, correction function 344 may exclude boundary region 72 from the calculation when determining pixel shift value PS_L between large-field-of-view live image 44 and large-field-of-view mask image 42 (see FIG. 7(b)). In addition, correction function 344 may exclude both region 71 and boundary region 72 from the calculation.

Below, we explain a modified method for calculating the pixel shift value PS_S of a small field of view image.

Figure 8 is a diagram illustrating a first modified example of the method for determining the pixel shift value PS_S of a small field of view image.

The correction function 344 may obtain a pixel shift value PS_L of the large field of view image and a pixel shift value PS_S of the small field of view image. In this case, the correction function 344 may compare the amount of misalignment resulting from provisionally applying both pixel shift values to provisionally align the small field of view image, and may then permanently apply the pixel shift value corresponding to the smaller amount of misalignment to align the small field of view image. This first modified example also makes it possible to align the small field of view image with higher accuracy than when aligning the small field of view image using only the small field of view image.

Figure 9 is a diagram illustrating a second variant of the method for determining the pixel shift value PS_S of a small field of view image.

The correction function 344 may provisionally determine the pixel shift value PS_S of the small-field-of-view image directly from the small-field-of-view live image 54 and the small-field-of-view mask image 52. In this case, if the amount of misalignment resulting from provisionally applying the pixel shift value to align the small-field-of-view image satisfies the termination condition (for example, if it is equal to or less than a threshold value), the pixel shift value is applied permanently. On the other hand, if the amount of misalignment does not satisfy the termination condition (for example, if it is greater than the threshold value), the correction function 344 determines the pixel shift value PS_L between the large-field-of-view live image 44 and the large-field-of-view mask image 42, converts it to a pixel shift value PS_S of the small-field-of-view image, and aligns the small-field-of-view image using the converted pixel shift value PS_S, as in the method shown in FIG. 6.

Figure 10 is a diagram illustrating a third modified example of the method for determining the pixel shift value PS_S of a small field of view image.

The correction function 344 may provisionally shift the small field of view image in advance by the pixel shift value PS_S obtained by converting the pixel shift value PS_L between the large field of view live image 44 and the large field of view mask image 42, and may directly obtain the pixel shift value PS_S from the small field of view image after the provisional shift. In this case, the pixel shift value PS_S may be calculated by normal calculation, or may be calculated in a restricted state that allows only small pixel shifts.

In this case, the pixel shift value PS_S obtained by converting the pixel shift value PS_L obtained from the large-field-of-view live image 44 and the large-field-of-view mask image 42 and the pixel shift value PS_S obtained directly from the small-field-of-view image after the temporary movement are provisionally applied to provisionally align the small-field-of-view image, and the resulting positional deviation amounts are compared, and the pixel shift value corresponding to the smaller positional deviation amount is actually applied to align the small-field-of-view image.

Figure 11 is a diagram illustrating a fourth variant of the method for determining the pixel shift value PS_S of a small field of view image.

The correction function 344 may set a first region of interest 81 corresponding to the small field of view image and a second region of interest 82 including the first region of interest 81 for the large field of view image, and determine a pixel shift value PS_L of the large field of view image with different weighting for the second region of interest 82 and the first region of interest 81. In this case, the correction function 344 may perform different weighting for, for example, an outer region 91 of the second region of interest, a region 92 obtained by excluding the first region of interest 81 from the second region of interest 82, and an inner region 93 of the first region of interest 81. The fourth modified example also allows the small field of view image to be aligned with higher accuracy than when the small field of view image is aligned using only the small field of view image.

Figure 12 is a diagram illustrating a fifth variant of the method for determining the pixel shift value PS_S of a small field of view image.

The correction function 344 may generate a composite image by fitting the small field of view image into an area of the large field of view image that corresponds to the small field of view image, and may determine the pixel shift value PS_L from the composite image. In this case, the composite image may be generated by enlarging the large field of view image to match the small field of view image (see FIG. 12), or may be generated by reducing the small field of view image to match the large field of view image. In either case, the field of view of the composite image (the subject portion included in the image) is the same as that of the large field of view image. When generating a composite image by enlarging the large field of view image to match the small field of view image, the high resolution of the small field of view image can be effectively utilized.

According to at least one of the embodiments described above, when X-rays are detected simultaneously by the first detector and the second detector, the small field of view image based on the second detector can be aligned with high accuracy.

In the above embodiment, the term "processor" refers to a circuit such as a dedicated or general-purpose CPU (Central Processing Unit), GPU (Graphics Processing Unit), or an Application Specific Integrated Circuit (ASIC), a programmable logic device (for example, a Simple Programmable Logic Device (SPLD), a Complex Programmable Logic Device (CPLD), and a Field Programmable Gate Array (FPGA)). When the processor is a CPU, for example, the processor realizes various functions by reading and executing a program stored in a memory circuit. When the processor is an ASIC, for example, instead of storing a program in a memory circuit, a function corresponding to the program is directly built into the processor circuit as a logic circuit. In this case, the processor realizes various functions by hardware processing that reads and executes the program built into the circuit. Alternatively, the processor can realize various functions by combining software processing and hardware processing.

In addition, in the above embodiment, an example was shown in which a single processor of the processing circuit realizes each function, but a processing circuit may be configured by combining multiple independent processors, and each processor may realize each function. In addition, when multiple processors are provided, a memory circuit for storing programs may be provided separately for each processor, or a single memory circuit may collectively store programs corresponding to the functions of all the processors.

Although several 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, modifications, and combinations of embodiments can be made without departing from the spirit of the invention. These embodiments and their modifications are within the scope of the invention and its equivalents as set forth in the claims, as well as the scope and spirit of the invention.

10 X-ray diagnostic apparatus 21 X-ray tube 24a First detector 24b Second detector 24c Scintillator 31 Display 34 Processing circuit 42 Large field of view mask image 44 Large field of view live image 52 Small field of view mask image 54 Small field of view live image 61 Device 342 Acquisition function 344 Correction function

Claims (10)

A scintillator that converts X-rays emitted from the X-ray tube into light;
a first detector and a second detector, which share the scintillator and simultaneously detect light converted by the scintillator and output electrical signals, respectively, and which have a smaller field of view and higher resolution than the first detector;
an X-ray detector having
a correction unit that corrects positional deviations in two second images generated from the electrical signals output by the second detector at two different time points by using two first images generated from the electrical signals output by the first detector at the two different time points ;
An X-ray diagnostic device comprising: The correction unit is
determining pixel shift values of the two first images generated from the electrical signals output by the first detector at the two different time points, converting the pixel shift values based on a field ratio between the first detector and the second detector, and using the converted pixel shift values to align the two second images generated from the electrical signals output by the second detector at the two different time points;
2. The X-ray diagnostic apparatus according to claim 1. The two different time points are:
A time point at which a mask image of the subject for generating a device image is viewed through the mask image and a time point at which a live image of the subject collected in real time is viewed through the mask image.
3. The X-ray diagnostic apparatus according to claim 2. The two different time points are:
a time point at which a mask image based on an image of the subject before administration of a contrast agent for generating a DSA image is captured, and a time point at which a plurality of time-series contrast images of the subject after administration of a contrast agent are captured.
4. The X-ray diagnostic apparatus according to claim 2 or 3. The correction unit is
determining pixel shift values for the two first images and pixel shift values for the two second images, comparing the amounts of misalignment resulting from provisionally aligning the two second images by provisionally applying both pixel shift values, and finally applying the pixel shift value corresponding to the smaller amount of misalignment to align the two second images and displaying them on a display;
5. An X-ray diagnostic apparatus according to claim 2. The correction unit is
a pixel shift value of the two second images is obtained, and when a positional deviation amount resulting from provisionally applying the pixel shift value to provisionally align the two second images is equal to or less than a threshold, the pixel shift value is applied permanently, whereas when the positional deviation amount is greater than the threshold, a pixel shift value of the two first images is obtained and converted based on a field ratio between the first detector and the second detector, and the converted pixel shift value is used to align the two second images.
5. An X-ray diagnostic apparatus according to claim 2. The correction unit is
determining pixel shift values of the two first images, converting the pixel shift values based on a field ratio between the first detector and the second detector, aligning the two second images using the converted pixel shift values, determining pixel shift values of the two second images after the alignment, comparing amounts of misalignment resulting from provisionally aligning the two second images by provisionally applying the pixel shift values determined after the alignment and the converted pixel shift values, and finally applying the pixel shift value corresponding to the smaller amount of misalignment to align the two second images and display them on a display;
7. An X-ray diagnostic apparatus according to claim 2. The correction unit is
a first region of interest corresponding to the second image and a second region of interest including the first region of interest are set for the first image, and pixel shift values of the two first images are obtained with different weights for the second region of interest and the first region of interest;
8. An X-ray diagnostic apparatus according to claim 2. The correction unit is
generating a composite image by fitting the second image into a region of the first image corresponding to the second image, determining a pixel shift value from the two composite images corresponding to the two different time points, converting the pixel shift value based on a field ratio between the first detector and the second detector, and aligning the two second images using the converted pixel shift value;
9. An X-ray diagnostic apparatus according to claim 2. an acquisition unit that acquires an output signal from an X-ray detector having a scintillator that converts X-rays irradiated from an X-ray tube into light, and a first detector and a second detector that share the scintillator, simultaneously detect the light converted by the scintillator, and output electrical signals, the first detector and the second detector having a smaller field of view and higher resolution than the first detector;
a correction unit that corrects positional deviations in two second images generated from the electrical signals output by the second detector at two different time points by using two first images generated from the electrical signals output by the first detector at the two different time points ;
A medical image processing device comprising:

Images