X-ray diagnostic apparatus and medical image processing apparatus.

Abstract

To precisely position a small visual field image based on a second detector when detecting X-rays with a first detector and the second detector simultaneously.SOLUTION: An X-ray diagnostic apparatus according to an embodiment comprises an X-ray detector and a correction unit. The X-ray detector includes: a scintillator for converting X-rays applied from an X-ray tube to light; and a first detector and a second detector with a smaller visual field and higher resolution than the first detector, both of the detectors sharing the scintillator, simultaneously detecting the light obtained by conversion by the scintillator, and respectively outputting electric signals. The correction unit corrects positional deviation in a second image generated from the electric signal output by the second detector, by using a first image generated from the electric signal output by the first detector.SELECTED DRAWING: Figure 6

Description

Technical Field

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

Background Art

[0002] Conventionally, in an examination using an X-ray diagnostic apparatus, there are cases where a narrow region of interest is observed at high resolution. For this reason, an X-ray diagnostic apparatus is known that includes a detector having a first detector with a large field of view employing a TFT (Thin Film Transistor) array and a second detector having a smaller field of view and a finer pixel pitch and higher resolution than the first detector using a CMOS (Complementary Metal Oxide Semiconductor).

[0003] In this type of X-ray diagnostic apparatus, 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 are displayed simultaneously (hereinafter referred to as high-resolution simultaneous display).

[0004] However, since the second detector has a small field of view, if there is a misalignment between two second images generated from electrical signals output at two different time points by the second detector, it is difficult to align these two second images.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to accurately align the small field of view image based on the second detector when simultaneously detecting X-rays with the first detector and the second detector. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problems. The problems corresponding to the respective effects of the respective configurations shown in the embodiments described later can also be regarded as other problems.

Means for Solving the Problems

[0007] 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 irradiated from an X-ray tube into light, and a first detector and a second detector that share the scintillator and simultaneously detect the light converted by the scintillator and output electrical signals respectively, where the field of view of the second detector is smaller and the resolution is higher than that of the first detector. The correction unit corrects the misalignment in the second image generated from the electrical signal output by the second detector using the first image generated from the electrical signal output by the first detector.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0009] Hereinafter, 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 guide wire.

[0010] FIG. 1 is a block diagram showing a configuration example of an X-ray diagnostic apparatus 10 including an image processing apparatus according to an embodiment. Note that the X-ray diagnostic apparatus 10 may be capable of continuous imaging of a plurality of frames, and includes, for example, an X-ray TV apparatus or an X-ray angiography apparatus.

[0011] As shown in FIG. 1, the X-ray diagnostic apparatus 10 includes an imaging apparatus 20 and a console 30 as an example of a medical image processing apparatus.

[0012] The imaging device 20 is usually installed in an examination room and is configured to generate image data regarding a subject. The console 30, as an example of a medical image processing device, is installed, for example, in an operation room adjacent to the examination room, generates an X-ray image based on the image data, and performs display. Note that the console 30 may be installed in the examination room where the imaging device 20 is installed, or may be installed at a remote location separated from the examination room and connected to the imaging device 20 via a network.

[0013] The imaging device 20 includes an X-ray tube 21, an X-ray movable diaphragm 22, a region of interest filter (hereinafter referred to as an ROI filter) 23, an FPD 24, a top plate 25, a high-voltage power supply 26, a diaphragm drive device 27, and a controller 29.

[0014] The X-ray tube 21 has a voltage applied thereto by the high-voltage power supply 26 and generates X-rays.

[0015] The X-ray movable diaphragm 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 forms a slit by a combination of a plurality of lead plates or the like. For example, the X-ray movable diaphragm 22 has two pairs of movable vanes, is controlled by the controller 29 via the diaphragm drive device 27, and adjusts the irradiation range of the X-rays irradiated from the X-ray tube 21 by opening and closing each pair of movable vanes.

[0016] The ROI filter 23 is composed of a flat plate such as copper or aluminum provided with an X-ray opening in part. The X-rays pass through the X-ray opening without attenuation, while passing through with attenuation by the ROI filter 23 in regions other than the X-ray opening. The shape of the X-ray opening may be, for example, a rectangle with a side length of about several mm to several tens of mm, or may be a circle, an ellipse, a polygon other than a rectangle, or the like. The ROI filter 23 is controlled by the controller 29 via the diaphragm drive device 27 and can move the position of the X-ray opening in parallel.

[0017] The FPD24 is composed of a flat panel detector (planar detector, FPD: Flat Panel Detector) having a plurality of X-ray detection elements (image sensor group), detects the X-rays irradiated on the FPD24, and based on the detected X-rays, outputs image data of an X-ray fluoroscopic image and an X-ray radiographic image (hereinafter, the X-ray fluoroscopic image and the X-ray radiographic image are collectively referred to as X-ray images) at a predetermined frame rate. This image data is provided to the console 30. More specifically, the FPD24 has a plurality of X-ray detection elements composed of semiconductor elements that accumulate signal charges according to the amount of incident X-rays. The plurality of X-ray detection elements are arranged in a matrix.

[0018] FIG. 2 is a block diagram showing a configuration example of the FPD24 according to the present embodiment.

[0019] For example, as shown in FIG. 2, the FPD24 has a first detector 24a, a second detector 24b, and a scintillator 24c. The first detector 24a and the scintillator 24c constitute a first FPD24d with a large field of view, and the second detector 24b and the scintillator 24c constitute a second FPD24e with a small field of view.

[0020] The scintillator 24c converts the X-rays irradiated from the X-ray tube 21 into light. The first detector 24a includes, for example, a two-dimensional image sensor employing a TFT (Thin Film Transistor) array formed of amorphous silicon, 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 employing a CMOS (Complementary Metal Oxide Semiconductor) transistor, detects the light converted by the scintillator 24c, and outputs an electrical signal. Note that the electrical signal output by the first detector 24a or the second detector 24b is also referred to as an X-ray signal.

[0021] Thus, the scintillator 24c is shared by the first detector 24a and the second detector 24b. In other words, the FPD 24 includes a scintillator 24c that converts 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 and detect the light converted by the scintillator 24c to output an electrical signal. Then, the first detector 24a and the second detector 24b respectively output electrical signals obtained by simultaneously detecting the light converted by the scintillator 24c.

[0022] Also, as shown in FIG. 2, the first detector 24a and the second detector 24b each have a plurality of element portions that are constituent units of pixels. Each of these element portions converts a fluorescence image obtained by X-ray incidence into an electrical signal and accumulates it in a photodiode (PD). In the example of FIG. 2, a case where the first detector 24a has eight element portions and the second detector 24b has eight element portions is illustrated.

[0023] Here, the pixel pitch of each element portion of the second detector 24b is finer than the pixel pitch of each element portion of the first detector 24a. In the example shown in FIG. 2, the pixel pitch of each element portion of the first detector 24a corresponds to the pixel pitch of two element portions of the second detector 24b. That is, 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.

[0024] In X-ray fluoroscopy, generally, an image is acquired with a weaker X-ray irradiation intensity compared to X-ray imaging. For this reason, although the X-ray fluoroscopy image is an image with low resolution, the dose to which the subject is exposed is small. The X-ray diagnostic apparatus 10 according to the present embodiment can perform both X-ray fluoroscopy and X-ray imaging (hereinafter collectively referred to as imaging).

[0025] The X-ray tube 21 and the FPD 24 may be arranged to face each other with the subject placed on the top plate 25 therebetween. For example, the X-ray tube 21 and the FPD 24 may be respectively supported at both ends of the C-arm so as to face each other with the subject therebetween. Further, the X-ray tube 21 and the FPD 24 may each be supported by an independent support member.

[0026] The top plate 25 is provided at the upper part of the bed and places the subject thereon. The high-voltage power supply 26 includes a high-voltage generator having a function of generating a high voltage to be applied to the X-ray tube 21, and an X-ray controller for controlling the output voltage according to the X-rays irradiated by the X-ray tube 21. The high-voltage generator may be of a transformer type or an inverter type.

[0027] 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 this memory circuit, and comprehensively controls each component of the imaging device 20. For example, the controller 29 is controlled by the console 30 to image the subject at a predetermined frame rate to generate image data and provide it to the console 30.

[0028] On the other hand, the console 30 has a display 31, an input interface 32, a memory circuit 33, and a processing circuit 34.

[0029] The display 31 is constituted by 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 under the control of the processing circuit 34.

[0030] The input interface 32 is realized by general input devices such as, for example, a trackball, a switch, a button, a mouse, a keyboard, a touch pad that performs an input operation by touching an operation surface, a non-contact input interface using an optical sensor, and a voice input interface, etc., and outputs an operation input signal corresponding to a user's operation to the processing circuit 34. Further, the input interface 32 may include a radiation switch that controls the on / off of radiation.

[0031] The memory circuit 33 has a configuration including a recording medium readable by a processor, such as a magnetic or optical recording medium or a semiconductor memory. Part 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.

[0032] The processing circuit 34 realizes a function of overall controlling the X-ray diagnostic apparatus 10. Further, the processing circuit 34 reads and executes an image processing program stored in the memory circuit 33, and when detecting X-rays simultaneously with the first detector 24a and the second detector 24b, accurately aligns a small field of view image based on the second detector 24b.

[0033] It is a processor that executes processing for

[0034] The processor of the processing circuit 34 realizes an imaging control function 341, an acquisition function 342, an image generation function 343, and a correction function 344 as shown in FIG. 1. Each of these functions is stored in the memory circuit 33 in the form of a program. Note that part of the functions 314-344 of the processing circuit 34 may be realized by an external processor connected to be able to transmit and receive data to and from the console 30 via a network.

[0035] The imaging control function 341 controls the X-ray imaging of a subject at a predetermined frame rate by controlling the imaging device 20.

[0036] The acquisition function 342 acquires output signals from each of the first detector 24a and the second detector 24b.

[0037] 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.

[0038] The correction function 344 corrects the misalignment 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. Specifically, the correction function 344 obtains the pixel shift values of two first images generated from the electrical signals output by the first detector 24a at two different time points, converts the pixel shift values based on the field of view ratio between the first detector 24a and the second detector 24b, and uses the converted pixel shift values to align two second images generated from the electrical signals output by the second detector 24b at two different time points.

[0039] FIG. 3 is a diagram for explaining the alignment of a conventional second image, and FIG. 4 is another diagram for explaining the alignment of a conventional second image.

[0040] Generally, when subtracting a mask image and a live contrast image to display an image, the amount of misalignment due to body movement or the like is calculated using image processing between the mask image and the contrast image, and subtraction is performed in a pixel-shifted state to reduce misregistration due to the misalignment.

[0041] By the way, when simultaneously displaying (high-resolution simultaneous display) the first image generated from the X-ray signal output by the first detector 24a and the second image generated from the X-ray signal output by the second detector 24b, images with different field-of-view sizes are simultaneously displayed. While checking the detailed situation in a narrow range, a fluoroscopic image with a large field of view is also displayed, so that the overall image can be easily grasped.

[0042] However, in the second image with a small field of view and high resolution, it may be difficult to correct the misalignment.

[0043] The reason that makes it difficult to correct the misalignment is that there are few feature points such as the outline of bones in the field of view of the second image. As shown in FIG. 3, the large-field mask image 42 corresponding to the large field of view 41 of the first detector 24a at the time of obtaining the mask image and the large-field live image 44 corresponding to the large field of view 43 of the first detector 24a at the time of obtaining the live image include the misalignment resulting from the body movement of the subject according to the time difference in the shooting timings of each other. Since both the large-field mask image 42 and the large-field live image 44 have a large field of view, they contain many feature points such as edges for image processing. Therefore, the pixel shift value can be easily and accurately obtained from the large-field mask image 42 and the large-field live image 44.

[0044] On the other hand, since the small-field mask image 52 and the small-field live image 54 have a small field of view, there are few feature points included in the images. In addition, in the small-field image, the outline of the bone is not considered important for the user to check the image and is often located at the end of the image, while the end of the screen is excluded from the target of image processing. Therefore, it is difficult to accurately obtain the pixel shift value from the small-field mask image 52 and the small-field live image 54.

[0045] Other causes that make it difficult to correct misalignment include that the ratio of a device such as a catheter is larger than feature points such as the outline of a bone included in the field of view of the second image, and the device is moving. As shown in FIG. 4, the ratio of the device 61 may be higher in the small-field live image 54 than in the large-field live image 44. In this case, due to the influence of the movement of the device, it is difficult to accurately obtain the pixel shift value from the small-field mask image 52 and the small-field live image 54.

[0046] Therefore, when performing high-resolution simultaneous display, the processing circuit 34 according to the present embodiment corrects the misalignment 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, thereby aligning the second image with high precision.

[0047] FIG. 5 is a flowchart showing an example of a procedure for correcting the misalignment of the small-field image generated from the electrical signal output by the second detector 24b by using the large-field image generated from the electrical signal output by the first detector 24a when performing high-resolution simultaneous display by the processor of the processing circuit 34 shown in FIG. 1. In FIG. 5, the symbols with numbers attached to S indicate each step of the flowchart.

[0048] FIG. 6 is a diagram for explaining a method of correcting the misalignment of the small-field image by using the large-field image.

[0049] First, in step S1, the acquisition function 342 acquires the output signals simultaneously detected and output by each of the first detector 24a and the second detector 24b.

[0050] Next, in step S2, the image generation function 343 generates the large-field mask image 42 from the electrical signal output by the first detector 24a and generates the small-field mask image 52 from the electrical signal output by the second detector 24b.

[0051] Next, in step S3, the acquisition function 342 acquires the output signals that are simultaneously detected and output by each of the first detector 24a and the second detector 24b. The image generation function 343 generates a large-field live image 44 from the electrical signal output by the first detector 24a and generates a small-field live image 54 from the electrical signal output by the second detector 24b.

[0052] Next, in step S4, the correction function 344 obtains the pixel shift value PS_L between the large-field live image 44 and the large-field mask image 42 (see the upper right of FIG. 6).

[0053] 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 image (see the lower right of FIG. 6).

[0054] 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. Then, the image generation function 343 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.

[0055] By the above procedure, when performing high-resolution simultaneous display, by correcting the misalignment of the small-field image using the large-field image, the small-field image can be aligned with high precision. By using the large-field image, the small-field image can be aligned with higher precision compared to the case of aligning the small-field image using only the small-field image.

[0056] For example, a fluoroscopic roadmap image in which a device image and a blood vessel image are combined may be used. In a scenario of generating a device image for such a fluoroscopic roadmap image, a device mask image based on X-ray fluoroscopy is used as a mask image, and a live image based on X-ray fluoroscopy is used as a live image, and the difference image between them can be used as a device extraction fluoroscopic image. Also, when performing coiling on an aneurysm of the cerebral blood vessels, etc., a rendering image of volume data obtained by an X-ray CT device or an X-ray diagnostic device may be used as the above-described blood vessel image. In such a scenario, when using an external image processing device, a pixel shift value PS_L may be given 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 perform alignment of the small field of view image.

[0057] Also, in a scenario of generating a DSA image, a mask image based on X-ray imaging before contrast agent administration can be used as a mask image, and a live image based on X-ray imaging after contrast agent administration can be used as a live image.

[0058] FIG. 7(a) is an explanatory diagram showing an example of a method for excluding the influence of the ROI filter 23, and (b) is an explanatory diagram showing another example. When using the ROI filter 23, the range in which X-rays are irradiated onto the detector through the aperture of the ROI filter 23 is often the same as the field of view of the second detector 24b.

[0059] When using the ROI filter 23, the dose is different between the region 71 on the detector corresponding to the aperture of the ROI filter and other regions. Therefore, when the correction function 344 obtains the pixel shift value PS_L between the large field of view live image 44 and the large field of view mask image 42, the region 71 may be excluded from the calculation target (see FIG. 7(a)).

[0060] In addition, since the dose in the boundary region 72 of the region 71 is affected by scattered radiation and diffraction, it may be significantly different from the doses in other regions. Therefore, when calculating the pixel shift value PS_L between the large-field live image 44 and the large-field mask image 42, the correction function 344 may exclude the boundary region 72 from the calculation target (see Fig. 7(b)). Further, the correction function 344 may exclude both the region 71 and the boundary region 72 from the calculation target.

[0061] Hereinafter, a modified example of the method for obtaining the pixel shift value PS_S of the small-field image will be described.

[0062] FIG. 8 is a diagram for explaining a first modified example of the method for obtaining the pixel shift value PS_S of the small-field image.

[0063] The correction function 344 may obtain the pixel shift value PS_L of the large-field image and the pixel shift value PS_S of the small-field image, respectively. In this case, the correction function 344 may compare the amount of misalignment in the result of temporarily applying both pixel shift values to temporarily align the small-field image, and perform the alignment of the small-field image by applying the pixel shift value corresponding to the smaller amount of misalignment. Also according to this first modified example, the small-field image can be aligned with higher accuracy compared to the case where the small-field image is aligned using only the small-field image.

[0064] FIG. 9 is a diagram for explaining a second modified example of the method for obtaining the pixel shift value PS_S of the small-field image.

[0065] The correction function 344 may temporarily obtain 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 in the result of temporarily applying the pixel shift value to temporarily align the small field of view image satisfies the end condition (for example, when it is below a threshold value), the pixel shift value is actually applied. On the other hand, if the amount of misalignment does not satisfy the end condition (for example, when it is greater than the threshold value), similar to the method shown in FIG. 6, the correction function 344 obtains 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 the pixel shift value PS_S of the small field of view image, and uses this converted pixel shift value PS_S to align the small field of view image.

[0066] FIG. 10 is a diagram for explaining a third modification example of a method for obtaining the pixel shift value PS_S of the small field of view image.

[0067] The correction function 344 may temporarily move the small field of view image by only the pixel shift value PS_S obtained by conversion from the pixel shift value PS_L between the large field of view live image 44 and the large field of view mask image 42 in advance, and directly obtain the pixel shift value PS_S from the temporarily moved small field of view image. In this case, for the calculation of the pixel shift value PS_S, normal calculation may be performed, or calculation may be performed in a restricted state that allows only minute pixel shifts.

[0068] In this case, the pixel shift value PS_S obtained by conversion from 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 directly obtained from the temporarily moved small field of view image are each temporarily applied to temporarily align the small field of view image, and the amounts of misalignment in the results are compared, and the pixel shift value corresponding to the smaller amount of misalignment may be actually applied to align the small field of view image.

[0069] FIG. 11 is a diagram for explaining a fourth modification example of a method for obtaining the pixel shift value PS_S of the small field of view image.

[0070] The correction function 344 may set, for the large-field-of-view image, 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, and obtain the pixel shift value PS_L of the large-field-of-view image with different weightings for the second region of interest 82 and the first region of interest 81. In this case, the correction function 344 may perform different weightings, for example, for the external region 91 of the second region of interest, the region 92 obtained by removing the first region of interest 81 from the second region of interest 82, and the internal region 93 of the first region of interest 81. Also according to the fourth modification example, the small-field-of-view image can be aligned with higher accuracy compared to the case where only the small-field-of-view image is used for aligning the small-field-of-view image.

[0071] FIG. 12 is a diagram for explaining a fifth modification example of a method for obtaining the pixel shift value PS_S of the small-field-of-view image.

[0072] The correction function 344 may generate a composite image by fitting the small-field-of-view image into the region of the large-field-of-view image corresponding to the small-field-of-view image for the large-field-of-view image, and obtain 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 in accordance with the small-field-of-view image (see FIG. 12), or the composite image may be generated by reducing the small-field-of-view image in accordance with 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 the composite image is generated by enlarging the large-field-of-view image in accordance with the small-field-of-view image, the high height of the resolution of the small-field-of-view image can be effectively utilized.

[0073] According to at least one of the embodiments described above, when the X-ray is 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.

[0074] In the above embodiment, the term "processor" means, for example, 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)), etc. When the processor is, for example, a CPU, the processor reads and executes a program stored in a storage circuit to realize various functions. When the processor is, for example, an ASIC, instead of storing a program in a storage circuit, a function corresponding to the program is directly incorporated as a logic circuit in the circuit of the processor. In this case, the processor realizes various functions by hardware processing of reading and executing the program incorporated in the circuit. Alternatively, the processor can also realize various functions by combining software processing and hardware processing.

[0075] In the above embodiment, an example in which a single processor of a processing circuit realizes each function has been shown. However, a processing circuit may be configured by combining a plurality of independent processors, and each processor may realize each function. When a plurality of processors are provided, the storage circuit for storing a program may be provided individually for each processor, or one storage circuit may store programs corresponding to the functions of all processors collectively.

[0076] Although several embodiments have been described, these embodiments are presented 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, changes, and combinations of embodiments can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, as well as in the invention described in the claims and its equivalent scope.

Explanation of Reference Numerals

[0077] 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

1. A scintillator that converts X-rays irradiated from an X-ray tube into light, a first detector that shares the scintillator and simultaneously detects the light converted by the scintillator and outputs electrical signals respectively, and a second detector that has a smaller field of view and higher resolution than the first detector, an X-ray detector having the same, a correction unit that corrects the misalignment in two second images generated from electrical signals output at two different times by the second detector, using two first images generated from electrical signals output at the two different times by the first detector, an X-ray diagnostic apparatus provided with the same.

2. The correction unit obtains the pixel shift values of the two first images generated from the electrical signals output at the two different times by the first detector, converts the pixel shift values based on the field of view ratio between the first detector and the second detector, and uses the converted pixel shift values to align the two second images generated from the electrical signals output at the two different times by the second detector. The X-ray diagnostic apparatus according to Claim 1.

3. The two different times are the time when a mask image of a subject for generating a device image is fluoroscoped and the time when a live image of the subject collected in real time is fluoroscoped. The X-ray diagnostic apparatus according to Claim 2.

4. The two different times are the time when a mask image based on an image of a subject before administration of a contrast agent for generating a DSA image is taken and the time when a plurality of temporal contrast images of the subject after administration of the contrast agent are taken. The X-ray diagnostic apparatus according to Claim 2 or 3.

5. The correction unit obtains the pixel shift values of the two first images and the pixel shift values of the two second images, compares the amount of misalignment in the result of temporarily applying both pixel shift values to temporarily align the two second images, and finally applies the pixel shift value corresponding to the smaller amount of misalignment to align the two second images and display them on a display. The X-ray diagnostic apparatus according to any one of Claims 2 to 4.

6. The correction unit Obtain the pixel shift values of the two second images, and if the amount of misalignment in the result of temporarily applying the pixel shift values to temporarily align the two second images is equal to or less than the threshold value, apply the pixel shift values. On the other hand, if the amount of misalignment is greater than the threshold value, obtain the pixel shift values of the two first images, convert them based on the field of view ratio between the first detector and the second detector, and use the converted pixel shift values to align the two second images. The X-ray diagnostic apparatus according to any one of claims 2 to 4.

7. The correction unit Obtain the pixel shift values of the two first images, convert the pixel shift values based on the field of view ratio between the first detector and the second detector, use the converted pixel shift values to align the two second images, obtain the pixel shift values of the two second images after the alignment, and compare the amount of misalignment in the result of temporarily applying each of the pixel shift values obtained after the alignment and the converted pixel shift values to temporarily align the two second images. Apply the pixel shift value corresponding to the smaller amount of misalignment to align the two second images and display them on the display. The X-ray diagnostic apparatus according to any one of claims 2 to 6.

8. The correction unit Set a first region of interest corresponding to the second image and a second region of interest including the first region of interest for the first image, and obtain the pixel shift values of the two first images with different weightings for the second region of interest and the first region of interest. The X-ray diagnostic apparatus according to any one of claims 2 to 7.

9. The correction unit For the first image, fit the second image into the region of the first image corresponding to the second image to generate a composite image, obtain the pixel shift values from the two composite images corresponding to the two different time points, convert the pixel shift values based on the field of view ratio between the first detector and the second detector, and use the converted pixel shift values to align the two second images. The X-ray diagnostic apparatus according to any one of claims 2 to 8.

10. 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, a first detector that shares the scintillator and simultaneously detects the light converted by the scintillator to output electrical signals respectively, and a second detector that has a smaller field of view and higher resolution than the first detector. A correction unit that corrects a positional shift in two second images generated from electrical signals output at two different time points by the second detector, using two first images generated from electrical signals output at the two different time points by the first detector. A medical image processing apparatus comprising the above.

Images