X-ray fluoroscopic imaging apparatus and image generation method

Abstract

To display, in real time, a fluoroscopic image subjected to super-resolution processing without requiring recognition or designation of a range of a subject image.SOLUTION: An X-ray image is generated from an output of an X-ray detector, and a field-of-view region corresponding to an irradiation region within the X-ray image is determined on the basis of a position of diaphragm blades of a movable diaphragm or the X-ray image. A magnification factor for enlarging the field-of-view region to a display image having a predetermined size is calculated. When the magnification factor is greater than a predetermined value, the X-ray image of the field-of-view region is enlarged to the size of the display image at the magnification factor while being subjected to high-resolution processing by first high-resolution processing. When the magnification factor is equal to or less than the predetermined value, the X-ray image of the field-of-view region is enlarged to the size of the display image at the magnification factor while being subjected to high-resolution processing by second high-resolution processing having a shorter processing time than the first high-resolution processing.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a process for increasing the resolution of a fluoroscopic image in an X-ray fluoroscopic imaging apparatus. [Background technology]

[0002] Some X-ray imaging devices are known to have a function for improving the resolution of an image by applying super-resolution processing to the acquired image (for example, Patent Document 1). However, super-resolution processing requires complex calculations and takes a long time to process. Therefore, the invention of Patent Document 1 applies super-resolution processing only to the area where the subject is present, thereby improving the image quality of the desired part of the image while suppressing an increase in processing time. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7120442 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the method of Patent Document 1 cannot reduce the processing time when the subject is present across the entire image, and also requires processing to recognize the range of the subject image from the image or to receive designation of the range of the subject image from the user.

[0005] When performing fluoroscopy (moving images) using an X-ray imaging device, it is necessary to perform image processing in real time at a predetermined frame rate. With a technique such as that disclosed in Patent Document 1, in which the range for super-resolution processing is set for each image by image processing or the like and then the super-resolution processing is performed for the set range, it is difficult to improve the frame rate.

[0006] An object of the present invention is to display a perspective image that has been subjected to advanced high-resolution processing in real time, without the need to recognize or specify the range of the subject image. [Means for solving the problem]

[0007] To achieve the above object, the present invention provides a system including a tabletop on which an object is placed, an X-ray tube that irradiates the object with X-rays, a movable diaphragm, a flat X-ray detector, an image processing device, and an image interpolation device. The movable diaphragm includes diaphragm blades arranged between the object and the X-ray tube and a drive unit that changes the position of the diaphragm blades, and adjusts the irradiation area of ​​the X-rays irradiated from the X-ray tube. The X-ray detector detects X-rays that have passed through the object and reached it. The image processing device generates an X-ray image from the output of the X-ray detector, determines a field of view corresponding to the irradiation area in the X-ray image based on the position of the diaphragm blades or the X-ray image obtained from the drive unit, and calculates a magnification ratio for enlarging the field of view to a display image of a predetermined size. If the magnification ratio is greater than a predetermined value, the image interpolation device performs a first high-resolution processing to enlarge the X-ray image of the field of view to the size of the display image at the magnification ratio while increasing the resolution, and if the magnification ratio is equal to or less than the predetermined value, the image interpolation device performs a second high-resolution processing that has a shorter processing time than the first high-resolution processing to enlarge the X-ray image of the field of view to the size of the display image at the magnification ratio while increasing the resolution. [Effects of the Invention]

[0008] According to the present invention, there is no need to recognize or specify the range of the subject image, and a perspective image that has been subjected to super-resolution processing is displayed in real time. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram showing the overall configuration of an X-ray fluoroscopic imaging apparatus according to a first embodiment of the present invention. [Figure 2] 4(a) to 4(d) are explanatory diagrams illustrating the relationship between the positions of the aperture blades of the X-ray fluoroscopic imaging apparatus of the first embodiment and image processing. [Figure 3] 4 is a flowchart showing the operation of the X-ray fluoroscopic imaging apparatus of the first embodiment. [Figure 4] 5(a) to 5(c) are views for explaining the binning process of the X-ray fluoroscopic imaging apparatus of the first embodiment. [Figure 5] 10(a) to 10(d) are explanatory diagrams illustrating the relationship between the positions of the aperture blades and image processing of the X-ray fluoroscopic imaging apparatus of the second embodiment. [Figure 6] 10 is a flowchart showing the operation of the X-ray fluoroscopic imaging apparatus of the second embodiment. [Figure 7] 10(a) to 10(c) are explanatory diagrams illustrating the relationship between the positions of the aperture blades and image processing of the X-ray fluoroscopic imaging apparatus of the third embodiment. [Figure 8] 10 is a flowchart showing the operation of the X-ray fluoroscopic imaging apparatus of the third embodiment. [Figure 9] 10(a) to 10(d) are explanatory diagrams illustrating the relationship between the positions of the aperture blades and image processing of the X-ray fluoroscopic imaging apparatus of the fourth embodiment. [Figure 10] 10 is a flowchart showing the operation of the X-ray fluoroscopic imaging apparatus of the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] An X-ray fluoroscopic imaging apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

[0011] <<Embodiment 1>> The X-ray fluoroscopic imaging apparatus of the first embodiment will be described with reference to Fig. 1 to Fig. 3. Fig. 1 is a block diagram showing the overall configuration of the X-ray fluoroscopic imaging apparatus of the first embodiment, and Fig. 2 is a diagram explaining image processing. Fig. 3 is a flowchart showing the operation of the X-ray fluoroscopic imaging apparatus.

[0012] The X-ray fluoroscopic imaging device of this embodiment determines the X-ray irradiation area in the X-ray image detected by the X-ray detector 11, i.e., the field of view 11a, based on the position of the aperture blades 13a or the X-ray image, and calculates an enlargement ratio for enlarging the field of view 11a to a display image 23a of a predetermined size. If the determined enlargement ratio is greater than a predetermined value L, the X-ray image of the field of view 11a is enlarged to the size of the display image 23a while increasing its resolution by a first resolution enhancement process (e.g., super-resolution process). On the other hand, if the enlargement ratio is equal to or less than the predetermined value, the X-ray image of the field of view 11a is enlarged to the size of the display image 23a while increasing its resolution by a second resolution enhancement process (e.g., general interpolation process) that has a shorter processing time than the first resolution enhancement process.

[0013] In this manner, in this embodiment, the magnification factor for converting the field of view 11a into a display image 23a of a predetermined size is calculated from the position of the diaphragm blades 13a, and the type of high-resolution processing is selected based on the magnification factor. This eliminates the need to recognize or specify the range of the subject image, and reduces the time required for processing that should be performed before the high-resolution processing.

[0014] Furthermore, when the magnification is large, the size of the field of view 11a is small, so even if high-resolution processing that requires a long calculation time is performed, such as super-resolution processing, the processing time can be reduced compared to when the field of view 11a is large, and a high-resolution image can be obtained. On the other hand, when the magnification is small, the size of the field of view 11a is large, so a high-resolution image can be obtained even with high-resolution processing that does not require a long calculation time, such as general interpolation processing. Therefore, by using the two types of processing appropriately depending on the magnification, a high-resolution image can be obtained while avoiding long processing times, and the image quality of the fluoroscopic image can be improved in real time.

[0015] The position of the diaphragm blades 13a that determine the size of the field of view 11a can be received from the user via the operation device 15.

[0016] Furthermore, as the first high resolution processing, for example, super-resolution processing using a learning model is performed, and as the second high resolution processing, processing without using a learning model is performed.

[0017] This will be explained in more detail below.

[0018] The X-ray fluoroscopic imaging device includes a tabletop 12 on which a subject 25 is placed, an X-ray tube 10 that irradiates the subject 25 with X-rays, a movable diaphragm 13, a flat-plate X-ray detector 11, an image processing device 20, an image interpolation device 21, a display image memory 22, and an image display device 23. The flat-plate X-ray detector 11 used here has X-ray detection elements arranged vertically and horizontally.

[0019] The movable diaphragm 13 is configured to include diaphragm blades 13a arranged between the subject 25 and the X-ray tube 10, and a driver 13b that changes the position of the diaphragm blades. The diaphragm blades 13a block part of the X-rays irradiated from the X-ray tube 10, and adjust the irradiation area (field of view range 11a) of the X-rays on the subject 25. In this configuration, the field of view range 11a is set by two pairs of opposing diaphragm blades 13a.

[0020] A high voltage generator 14 that supplies a tube current and a tube voltage is connected to the X-ray tube 10. A system control device 16 is connected to the high voltage generator 14 and the adjustable aperture 13. The system control device 16 controls the operations of the high voltage generator 14 and the adjustable aperture 13.

[0021] An operation unit 15 is also connected to the system control device 16. The operation unit 15 is provided with a field of view size selection button 15a and an aperture lever 15b.

[0022] The field of view size selection button 15a is a button for selecting one of a plurality of predetermined field of view sizes (for example, sizes B0, B1, B2, and B3). Each field of view size corresponds to a predetermined position of the diaphragm blades 13a. The driving unit 13b moves the diaphragm blades 13a to a position corresponding to the field of view size selected by the field of view size selection button 15a.

[0023] The aperture lever 15b is a lever that moves the aperture blades 13a to a position desired by the operator. The drive unit 13b moves the aperture blades 13a to the position operated by the aperture lever 15b. The aperture blades 13a may be single-acting aperture blades that are moved one by one by the aperture lever 15b, or may be linked aperture blades that move one pair or two pairs of aperture blades 13a in a linked manner.

[0024] The operator can adjust the position of the diaphragm blades 13a by operating the field of view size selection button 15a or the diaphragm lever 15b using the operation device 15, and set the size of the field of view range 11a to a desired size.

[0025] The tabletop 12 also has a built-in mechanism for moving the tabletop 12 at least within its main plane. A mechanism control device 17 is connected to the mechanism and controls the mechanism. By moving the tabletop 12 within its main plane, the mechanism control device 17 can relatively change the positional relationship between the X-ray tube 10 and the tabletop 12, thereby relatively moving the field of view of the movable diaphragm 13 on the subject. The mechanism control device 17 may also move an arm (not shown) that supports the X-ray tube 10 in a direction parallel to the main plane of the tabletop 12.

[0026] The image processing device 20 can operate in a fluoroscopy mode and an imaging mode. In the fluoroscopy mode, the X-ray tube 10 emits X-rays at a predetermined imaging rate under the control of the system control device 16. The image processing device 20 generates an X-ray image at a predetermined rate from the output of the X-ray detector 11. In the imaging mode, the X-ray tube 10 emits X-rays only once under the control of the system control device 16. The amount of X-rays emitted in the imaging mode is generally greater than the amount of X-rays emitted in the fluoroscopy mode. The image processing device 20 generates a still X-ray image from the output of the X-ray detector 11.

[0027] The operation of each unit will be described in more detail below with reference to FIGS.

[0028] The system control device 16, the image processing device 20, and the image interpolation device 21 are configured by a computer or the like equipped with a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit) and a memory. The CPU or the like reads and executes a program stored in the memory (storage unit), thereby realizing the functions of the system control device 16, the image processing device 20, and the image interpolation device 21.

[0029] The image processing device 20 and the image interpolation device 21 can be configured in part or in whole by hardware. For example, a circuit design can be performed to realize the functions of the system control device 16, the image processing device 20, and the image interpolation device 21 using a custom IC such as an ASIC (Application Specific Integrated Circuit) or a programmable IC such as an FPGA (Field-Programmable Gate Array).

[0030] (Step S101) System control device 16 accepts the field of view size selected by the operator using field of view size selection button 15a of operation device 15, or the position of diaphragm blades 13a specified using diaphragm lever 15b. In this embodiment, the field of view size selected using field of view size selection button 15a has an aspect ratio of 1. The aspect ratio of display image 23a is also 1.

[0031] The system control device 16 instructs the drive unit 13b to move the aperture blades 13a to a predetermined position of the aperture blades 13a corresponding to the field of view size selected by the field of view size selection button 15a, or to a position of the aperture blades 13a specified by the aperture lever 15b.

[0032] (Step S102) When the operator issues a command to start fluoroscopy using the operation device 15, the system control device 16 causes the high voltage generator 14 to supply a predetermined tube voltage and tube current for fluoroscopy to the X-ray tube 10, causing the X-ray tube 10 to irradiate X-rays onto the subject 25. As a result, X-rays narrowed down to the field of view range 11a by the diaphragm blades 13a are irradiated onto the subject 25, and the X-rays that have passed through the subject 25 are detected by the X-ray detector 11.

[0033] (Step S103) The X-ray detector 11, in which X-ray detection elements are arranged vertically and horizontally, sends the output of the X-ray detection elements to an image processing device 20.

[0034] The image processing device 20 generates an X-ray image of the entire surface of the X-ray detector 11 (including the area where the X-rays are blocked by the aperture blades 13a) from the output of the X-ray detection elements received from the X-ray detector 11.

[0035] (Step S104) The image processing device 20 performs predetermined image processing such as noise reduction, normalization, and motion correction on the X-ray image generated in step 103. However, this image processing does not include enlargement processing or high-resolution processing. The image after this image processing is an X-ray image of the entire surface of the X-ray detector 11 (including the area where X-rays are blocked by the aperture blades 13a).

[0036] (Step S105) The image processing device 20 receives the position of the aperture blade 13a of the variable aperture 13 from the system control device 16, and calculates, from the position of the aperture blade 13a, an area A (field of view range 11a) that is not blocked by the aperture blade 13a in the image after processing in step S104.

[0037] Alternatively, in the X-ray image after processing in step S104, the peripheral portion of the image where the detected X-ray value is low is extracted by image processing such as binarization processing, and the area A (field of view range 11a) that is not blocked by the aperture blades 13a is calculated based on the X-ray image.

[0038] (Step S106) The image processing device 20 extracts an X-ray image of the region A (field of view 11a) that is not blocked by the diaphragm blades 13a, which was calculated in step S105. The extracted X-ray image of the region A (field of view 11a) is stored in the display image memory 22.

[0039] (Step S107) The image processing device 20 calculates the magnification ratio for enlarging the image in the area A (field of view range 11a) to a display image B of a predetermined size to be displayed on the image display device 23. Specifically, the magnification ratio is calculated by dividing the number of pixels on one side of the display image B of the predetermined size by the number of pixels on the corresponding side of the image in the area A (field of view range 11a).

[0040] Furthermore, the image processing device 20 determines whether the calculated magnification is greater than a predetermined value L. The determination result is stored in the display image memory 22 in association with the X-ray image of the cut-out region A (field of view range 11a).

[0041] (Step S108) If the magnification ratio of the image of area A (field of view range 11a) stored in display image memory 22 is equal to or less than a predetermined threshold L, in step S108, image interpolation device 21 performs a second high-resolution process with a short calculation time (for example, a general interpolation process that does not use a learning model such as the widely known Bicubic process) to enlarge the X-ray image of area A (field of view range 11a) cut out in step S106 to the size of display image B (display image 23a) while increasing the resolution.

[0042] (Step S109) On the other hand, if the magnification ratio of the image of area A (field of view range 11a) stored in display image memory 22 is greater than a predetermined threshold L, in step S109, the image interpolation device 21 performs a first high-resolution process (e.g., super-resolution process using a learning model) that requires a long calculation time but can achieve high-definition resolution, and enlarges the X-ray image of area A (field of view range 11a) cut out in step S106 to the size of display image B (display image 23a) while increasing its resolution.

[0043] (Step S110) In step S108 or S109, the image interpolation device 21 causes the image display device 23 to display the enlarged display image 23a with increased resolution.

[0044] By repeating the above steps S101 to S110 at a predetermined frame rate until the operation device 15 receives an end instruction from the operator, a perspective image (moving image) can be displayed on the image display device .

[0045] A further explanation will be given using a specific example shown in FIGS. 2(a) to 2(d).

[0046] 2(a), the size of the display image 23a to be displayed on the image display device 23 is set in advance to 1000×1000 pixels (height×width). In addition, the threshold value L of the magnification ratio for determining whether or not to perform high-resolution processing using a learning model is set to 1.5.

[0047] 2(a), in step S101, when the operator presses the B0 button of the field of view size selection buttons 15a and places the diaphragm blade 13a at a position where the field of view 11a is 1000 x 1000 pixels in length x width, the image processing device 20 determines in step S105 that area A (field of view 11a) is 1000 x 1000 pixels from the position of the diaphragm blade 13a. In step S106, the image processing device 20 cuts out an image of the field of view 11a.

[0048] The image processing device 20 calculates the magnification ratio for enlarging the image of the area A (field of view 11a) to the size of the display image B (display image 23a). Here, the magnification ratio for both the vertical and horizontal sides is B / A=1000 / 1000=1.

[0049] Therefore, since the magnification rate is 1 and is equal to or less than the threshold value L (=1.5), in step S108, the image interpolation device 21 performs a second high resolution process (for example, bicubic process that does not use a learning model) that requires a short calculation time to enlarge the X-ray image of the area A (field of view range 11a) while increasing the resolution to the size of the display image B (display image 23a), and displays it on the image display device 23. Note that since the magnification rate is 1 here, the size does not change.

[0050] Next, as shown in Figure 2(b), if the operator presses the B1 button of the field of view size selection buttons 15a and positions the diaphragm blade 13a so that the field of view 11a is 800 x 800 pixels in length x width, the image processing device 20 cuts out an image of the field of view 11a of 800 x 800 pixels. The magnification ratio is B / A = 1000 / 800 = 1.25.

[0051] Therefore, since the magnification ratio is 1.25, which is less than the threshold value L (=1.5), the image interpolation device 21 performs a second high-resolution process (e.g., bicubic process) which has a short calculation time, and enlarges the X-ray image of the 800 x 800 pixel field of view 11a while increasing the resolution to the size of a display image 23a of 1000 x 1000 pixels, and displays it on the image display device 23.

[0052] Next, as shown in Figure 2(c), when the operator presses the B2 button of the field of view size selection button 15a and positions the diaphragm blade 13a so that the field of view range 11a is 500 x 500 pixels in length x width, the image processing device 20 cuts out an image of the field of view range 11a of 500 x 500 pixels. The magnification ratio is B / A = 1000 / 500 = 2.

[0053] Therefore, since the magnification ratio is 2, which is greater than the threshold value L (= 1.5), the image interpolation device 21 performs a first high-resolution process (e.g., super-resolution process using a learning model) which requires a long calculation time but produces a high-resolution image, thereby enlarging the X-ray image of the 500 x 500 pixel field of view 11a to the size of a display image 23a of 1000 x 1000 pixels while increasing the resolution, and displays it on the image display device 23.

[0054] 2(d), when the operator presses the B3 button of the field of view size selection button 15a and positions the diaphragm blade 13a so that the field of view 11a is 200 x 200 pixels in length x width, the image processing device 20 cuts out an image of the field of view 11a of 200 x 200 pixels. The magnification ratio is B / A = 1000 / 200 = 5.

[0055] Therefore, since the magnification ratio is 5, which is greater than the threshold value L (= 1.5), the image interpolation device 21 performs a first high-resolution process (e.g., super-resolution process using a learning model) which requires a long calculation time but produces a high-resolution image, thereby enlarging the X-ray image of the 200 x 200 pixel field of view 11a to the size of a display image 23a of 1000 x 1000 pixels while increasing the resolution, and displays it on the image display device 23.

[0056] As described above, in this embodiment 1, the magnification ratio for enlarging area A (field of view range 11a) to area B (display image 23a) of a predetermined size is calculated based on the position of the aperture blades 13a of the movable aperture 13, and depending on this magnification ratio, a general second high-resolution processing (e.g., bicubic processing) which requires a short calculation time, or a first high-resolution processing (e.g., super-resolution processing using a learning model) which requires a long calculation time is selected.

[0057] When the magnification rate is small, the size of area A (field of view 11a) is large, and the time required for image processing, including high-resolution processing, increases. Therefore, in fluoroscopic imaging, which displays several to several tens of images per second, real-time image display tends to be delayed. However, a small magnification rate means that the size difference between the image of area A (field of view 11a) before magnification and the displayed image B after magnification is small, so the image can be magnified to a relatively high resolution even with high-resolution processing that requires a short calculation time, such as bicubic interpolation.

[0058] Conversely, when the magnification is large, the image size of the area A (field of view range 11a) before magnification is small, and the processing time is shorter than when the image size is large. Therefore, even when performing high-resolution processing using a learning model that requires a long calculation time, the processing time can be reduced compared to when processing large images. Moreover, compared to performing a general second high-resolution processing (e.g., bicubic processing) that requires a short calculation time, it is easier to obtain a high-resolution display image even when the magnification is large.

[0059] As described above, in the X-ray fluoroscopic imaging device of this embodiment 1, by changing the type of high-resolution processing based on the magnification ratio, it is possible to obtain high-resolution enlarged images while avoiding long processing times, and to display high-resolution fluoroscopic images in real time.

[0060] The processing flow of FIG. 3 can be applied not only to fluoroscopy but also to radiography.

[0061] In the flow of FIG. 3, step S104 for performing image processing such as noise reduction may be performed after step S106 for cutting out area A (field of view range 11a).

[0062] <<Embodiment 2>> The X-ray fluoroscopic imaging apparatus of the second embodiment will be described with reference to Fig. 4 to Fig. 6. Fig. 4 is a diagram for explaining binning processing, and Fig. 5 is a diagram for explaining image processing of the apparatus of the second embodiment. Fig. 6 is a flowchart showing the operation of the apparatus of the second embodiment.

[0063] The X-ray fluoroscopic imaging device of the second embodiment is basically the same as the device of the first embodiment, but differs from the first embodiment in that the X-ray detector 11 is provided with a binning processing circuit and performs binning processing to bundle the outputs of the X-ray detection elements arranged vertically and horizontally according to the field of view size selected by the field of view size selection button 15a.

[0064] When the binning processing circuit of the X-ray detector 11 performs binning with a binning size of N, the outputs of the X-ray detection elements arranged vertically and horizontally as shown in Fig. 4(a) are bundled (added) together for each of the X-ray detection elements (vertical × horizontal = N × N) as shown in Fig. 4(c) and output as an X-ray detection value for one pixel. On the other hand, when the X-ray detector 11 does not perform binning (binning size N = 1), the output of each X-ray detection element is output as an X-ray detection value for one pixel as shown in Fig. 4(b).

[0065] By having the binning processing circuit of the X-ray detector 11 perform binning, even if the X-ray detector 11 has a greater number of X-ray detection elements than the number of pixels of the display image 23a, it becomes possible to generate and display the display image 23a using the outputs of the X-ray detection elements on the entire surface of the X-ray detector 11. Furthermore, binning generally enables fluoroscopy with a lower dose than non-binning.

[0066] On the other hand, because binning reduces the resolution to 1 / N, the size (number of pixels) of area A (field of view range 11a) is also reduced to 1 / N. In other words, the magnification factor when the image of area A (field of view range 11a) is enlarged to display image 23a is greater than when binning is not performed. Therefore, the magnification factor differs depending on the combination of the field of view size selected using field of view size selection button 15a and binning size N. In the second embodiment, whether to enlarge the image using the first high-resolution processing or the second high-resolution processing is determined according to the magnification factor calculated reflecting the binning size N.

[0067] The operation of each part of the X-ray fluoroscopic imaging apparatus of the second embodiment will be described below with reference to FIGS.

[0068] As a prerequisite, the X-ray detector 11 has 3000 x 3000 X-ray detection elements in length x width.

[0069] When size B0 of field size selection button 15a is selected, the size of area A (field of view range 11a) of aperture 13 is 3000 x 3000 pixels (height x width). When size B1 is selected, field of view range 11a is 1500 x 1500 pixels (height x width). When size B2 is selected, field of view range 11a is 1000 x 1000 pixels (height x width). When size B3 is selected, field of view range 11a is 500 x 500 pixels (height x width).

[0070] When the operator selects size B0 or ​​B1 using the field of view size selection button 15a, the system control device 16 instructs the X-ray detector 11 to perform binning with a binning size N=3, and when the operator selects size B2 or B3, the system control device 16 instructs the X-ray detector 11 not to perform binning (i.e., binning size N=1).

[0071] The display image 23a has a size of 1000×1000 pixels in height×width, the same as in the first embodiment.

[0072] (Step S201) First, the system control device 16 receives the field of view size selected by the operator using the field of view size selection button 15 a of the operation device 15 .

[0073] (Step S202) System control device 16 instructs drive unit 13b to move diaphragm blade 13a to a predetermined position of diaphragm blade 13a that corresponds to the field of view size selected by field of view size selection button 15a.

[0074] Furthermore, the system control device 16 sets a predetermined binning size N corresponding to the field of view size selected by the field of view size selection button 15a in the X-ray detection device 11. Here, if the field of view size B0 or ​​B1 is selected, N=3 is set, and if B2 or B2 is selected, N=1 is set.

[0075] (Step S203) When the operator issues a command to start fluoroscopy using the operation device 15, the system control device 16 causes the X-ray tube 10 to irradiate the subject 25 with X-rays. As a result, the subject 25 is irradiated with X-rays narrowed down to the field of view 11a by the aperture blades 13a, and the X-rays that have passed through the subject 25 are detected by the X-ray detector 11.

[0076] (Step S204) If the binning size N set in step S202 is N=1, the X-ray detector 11 does not perform binning and proceeds to step S206. If N=1 is not true, the X-ray detector 11 performs binning and proceeds to step S205.

[0077] (Step S205) The binning processing circuit of the X-ray detector 11 bundles (adds up) the outputs of each of the vertical×horizontal=N×N X-ray detection elements to obtain an X-ray detection value for one pixel.

[0078] (Step S206) When binning is not performed, the X-ray detector 11 regards the output of one X-ray detection element as one pixel, and when binning is performed, the X-ray detector 11 sends the output of one pixel bundled after binning to the image processing device 20.

[0079] The image processing device 20 generates an X-ray image of the entire surface of the X-ray detector 11 (including the area where the X-rays are blocked by the aperture blades 13a) from the output of the X-ray detection elements received from the X-ray detector 11.

[0080] (Step S207) The image processing device 20 performs predetermined image processing such as noise reduction, normalization, and motion correction on the X-ray image generated in step 103. However, this image processing does not include enlargement processing or high-resolution processing. The image after this image processing is an X-ray image of the entire surface of the X-ray detector 11 (including the area where X-rays are blocked by the aperture blades 13a).

[0081] (Step S208) The image processing device 20 receives the position of the aperture blades 13a of the variable aperture 13 from the system control device 16, and calculates, from the position of the aperture blades 13a, an area A (field of view range 11a) that is not blocked by the aperture blades 13a in the image after processing in step S206.

[0082] At this time, in the second embodiment, the X-ray detector 11 performs predetermined binning in accordance with the field of view size selected with the field of view size selection button 15a in step S205. Therefore, in the case of a field of view size for which the X-ray detector 11 is performing binning, the image processing device 20 calculates the size of the region A (field of view range 11a) after binning by the X-ray detector 11 as the region A (field of view range 11a) that is not blocked by the diaphragm blades 13a. Specifically, when the field of view size B0 or ​​B1 is selected with the field of view size selection button 15a, the X-ray detector 11 performs binning with a binning size N=3. Therefore, when calculating the size of the region A (field of view range 11a) that is not blocked by the diaphragm blades 13a from the position of the diaphragm blades 13a, the image processing device 20 calculates the region corresponding to the position of the diaphragm blades 13a by dividing the region by 1 / N=1 / 3, and sets this as the region A (field of view range 11a). In addition, when the image processing device 20 calculates the area A (field of view range 11a) that is not blocked by the aperture blades 13a based on the X-ray image by image processing the X-ray image, it processes the binned X-ray image received from the X-ray detector 11 to calculate the area A (field of view range 11a). (Step S209) The image processing device 20 cuts out the X-ray image of the area A (field of view 11a) calculated in step S208. The X-ray image of the cut-out area A (field of view 11a) is stored in the display image memory 22.

[0083] (Step S210) The image processing device 20 calculates the magnification ratio for enlarging the image of the area A (field of view range 11a) cut out in step 208 to a display image B of a predetermined size to be displayed on the image display device 23. Specifically, the magnification ratio is calculated by dividing the number of pixels on one side of the display image B of the predetermined size by the number of pixels on the corresponding side of the image of the area A (field of view range 11a).

[0084] As explained in step 208, if binning is performed, the size of the area A (field of view range 11a) is the size of the area A (field of view range 11a) after binning.

[0085] Furthermore, the image processing device 20 determines whether the calculated magnification is greater than a predetermined value L. The determination result is stored in the display image memory 22 in association with the X-ray image of the cut-out region A (field of view range 11a).

[0086] (Step S211) When the magnification ratio of the image of area A (field of view range 11a) stored in display image memory 22 is equal to or less than a predetermined threshold L, image interpolation device 21 performs a second high-resolution process (e.g., bicubic process) with a short calculation time, similar to step S108 in embodiment 1, to increase the resolution and enlarge the image to the size of display image B (display image 23a).

[0087] (Step S212) On the other hand, when the magnification ratio of the image of area A (field of view range 11a) stored in display image memory 22 is greater than a predetermined threshold L, image interpolation device 21 performs a first high resolution process (e.g., super-resolution process using a learning model) that can achieve high resolution, similar to step S109 in embodiment 1, and enlarges the image to the size of display image B (display image 23a) while increasing the resolution.

[0088] (Step S213) In step S211 or S212, the image interpolation device 21 causes the image display device 23 to display the display image 23a that has been enlarged and has a higher resolution.

[0089] By repeating the above steps S201 to S213 at a predetermined frame rate until the operation device 15 receives an end instruction from the operator, a perspective image (moving image) can be displayed on the image display device .

[0090] A further explanation will be given using the specific example shown in FIGS. 5(a) to 5(d).

[0091] As described above, the X-ray detector 11 has 3000×3000 X-ray detection elements. The display image 23a has 1000×1000 pixels, the same as in the first embodiment.

[0092] In addition, the threshold value of the enlargement ratio for determining whether or not to perform the first high resolution processing using the learning model is set to L=1.5.

[0093] 5(a), when the operator selects size B0 of field of view size selection button 15a, the size of area A (field of view range 11a) of aperture 13 is 3000×3000 pixels in height×width. Also, binning is performed in X-ray detector 11 with a binning number N=3.

[0094] Therefore, the aperture blade 13a is positioned at a position where the field of view range 11a is 3000 x 3000 pixels in height x width, but in step S205, the X-ray detector 11 performs binning with a binning number N=3, and the field of view range 11a is 1000 x 1000 pixels in height x width.

[0095] The magnification ratio for enlarging the image of area A (field of view 11a) to the size of display image B (display image 23a) is magnification ratio=B / A=1000 / 1000=1.

[0096] Therefore, since the magnification ratio is 1, which is less than the threshold value L (=1.5), in step S211, the image interpolation device 21 performs a second high-resolution process (e.g., bicubic process) which has a short calculation time, and enlarges the X-ray image of area A (field of view range 11a) to the size of display image B (display image 23a) while increasing the resolution, and displays it on the image display device 23.

[0097] 5(b), when the operator selects size B1 of the field of view size selection button 15a, the size of the area A (field of view range 11a) of the aperture 13 is 1500×1500 pixels in length×width. Also, in the X-ray detector 11, binning is performed with a binning number N=3.

[0098] Therefore, the aperture blade 13a is positioned at a position where the field of view range 11a is 1500 x 1500 pixels in height x width, but in step S205, the X-ray detector 11 performs binning with a binning number N=3, and the field of view range 11a becomes 500 x 500 pixels in height x width.

[0099] The magnification ratio is B / A=1000 / 500=2, which is greater than the threshold value L (=1.5). Therefore, in step S212, the image interpolation device 21 enlarges the X-ray image of the field of view 11a to the size of the display image 23a by a first high resolution processing (e.g., super-resolution processing using a learning model), which requires a long calculation time but produces a high-resolution image.

[0100] Next, as shown in FIG. 5(c), when the operator selects size B2 of the field of view size selection button 15a, the size of area A (field of view range 11a) of the aperture 13 is 1000×1000 pixels (vertical×horizontal). Also, binning is not performed. Therefore, the field of view range 11a is 1000×1000 pixels (vertical×horizontal).

[0101] The magnification ratio for enlarging the image of area A (field of view range 11a) to the size of display image B (display image 23a) is magnification ratio = B / A = 1000 / 1000 = 1, which is less than the threshold value L (= 1.5). Therefore, in step S211, the image interpolation device 21 enlarges the X-ray image of area A (field of view range 11a) to the size of display image B (display image 23a) while increasing the resolution by using a second high-resolution processing (e.g., bicubic processing) which has a short calculation time.

[0102] Next, as shown in Figure 5(d), when the operator selects size B3 of the field of view size selection button 15a, the size of area A (field of view range 11a) of the aperture 13 is 500 x 500 pixels in length x width. Binning is not performed.

[0103] Therefore, the field of view 11a is 500 x 500 pixels in length x width, and the magnification ratio is B / A = 1000 / 500 = 2, which is greater than the threshold value L (= 1.5). Therefore, in step S212, the image interpolation device 21 enlarges the X-ray image of the field of view 11a to the size of the display image 23a by a first high-resolution processing (e.g., super-resolution processing using a learning model), which requires a long calculation time but produces a high-resolution image.

[0104] As described above, in the second embodiment, even when binning processing is performed, the size of the field of view 11a after binning processing is used to set the magnification factor for the display image 23a, thereby allowing the first high-resolution processing (e.g., bicubic processing) or the second high-resolution processing (e.g., super-resolution processing using a learning model) to be selected and performed.

[0105] As a result, in embodiment 2, even when an X-ray detector 11 having a larger number of pixels than the display image 23a is used, the binning process makes it possible to display an image of the entire surface of the X-ray detector 11, and furthermore, since the output of the elements can be bundled, the X-ray dose can be reduced, thereby reducing the amount of exposure.

[0106] At the same time, as in the first embodiment, a high-resolution enlarged image can be obtained while avoiding an increase in processing time, and a high-resolution fluoroscopic image can be displayed in real time.

[0107] Furthermore, since the first or second resolution increasing process is performed, even if the binning process is performed during fluoroscopy, the image resolution is not reduced, and the display image 23a can continue to be displayed with high resolution.

[0108] <<Embodiment 3>> The X-ray fluoroscopic imaging apparatus of the third embodiment will be described with reference to Fig. 7 and Fig. 8. Fig. 7 is a diagram for explaining the operation of the apparatus of the third embodiment, and Fig. 8 is a flowchart showing the operation of the apparatus of the third embodiment.

[0109] The X-ray fluoroscopic imaging device of embodiment 1 was configured to enlarge and display an image of the field of view size 11a selected with the field of view size selection button 15a to the display image 23a. The X-ray fluoroscopic imaging device of embodiment 3 has a function (called field of view full screen enlargement) that, when the operator selects a field of view size with the field of view size selection button 15a and then further narrows the field of view range 11a within the field of view size selected with the field of view size selection button 15a using the aperture lever 15b, enlarges and displays the field of view range 11a adjusted with the aperture lever 15b to the screen (display image 23a).

[0110] When enlarging, either the first high-resolution processing (e.g., Bicubic processing) or the second high-resolution processing (e.g., super-resolution processing using a learning model) is selected and performed depending on the enlargement ratio.

[0111] In addition, if the aspect ratio of the field of view 11a adjusted by the aperture lever 15b is not 1, The long side is enlarged to the length of the corresponding side of the display image 23a.

[0112] The operation of the X-ray fluoroscopic imaging apparatus of the third embodiment will be described with reference to Figures 7 and 8. In the flow of Figure 8, the same processes as those in the flow of Figure 3 of the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0113] (Step S301) 3, system control device 16 receives the field of view size selected by the operator using field of view size selection button 15a of operation device 15. System control device 16 instructs drive unit 13b to move diaphragm blade 13a to a predetermined position of diaphragm blade 13a that corresponds to the field of view size selected using field of view size selection button 15a.

[0114] (Step S302) The system control device 16 receives the position of the diaphragm blades 13a set by the operator using the diaphragm lever 15b of the controller 15. The diaphragm lever 15b can specify the position of the diaphragm blades 13a within the field of view range selected in step 301 using the field of view size selection button 15a.

[0115] 7, the aperture lever 15b includes a lever 15b-1 that moves a pair of aperture blades 13a in the vertical direction of the field of view in an interlocking manner, and a lever 15b-2 that moves a pair of aperture blades 13a in the horizontal direction of the field of view in an interlocking manner. Thus, by moving the levers 15b-1 and 15b-2, the operator can arbitrarily set the aspect ratio of the field of view range 11a.

[0116] The system control device 16 moves the aperture blades 13a to the position designated by the aperture lever 15b.

[0117] (Step S303) The system control device 16 reads and accepts whether the operator has turned on the full-screen field of view enlargement button (not shown) of the operation device 15.

[0118] (Steps S102 to S104) Steps S102 to S105 are performed in the same manner as in the first embodiment.

[0119] That is, when the operator issues a command to start fluoroscopy using the operation device 15, the system control device 16 causes the X-ray tube 10 to irradiate the subject 25 with X-rays (step S102). The X-rays that have passed through the subject 25 are detected by the X-ray detector 11.

[0120] The X-ray detector 11 sends the output of the X-ray detection elements to the image processing device 20 (step S103). The image processing device 20 generates an X-ray image of the entire surface of the X-ray detector 11 (including the area where the X-rays are blocked by the aperture blades 13a) from the output of the X-ray detection elements.

[0121] The image processing device 20 performs predetermined image processing such as noise reduction, normalization, and motion correction on the X-ray image generated in step S103 (step S104). The image after this image processing is an image of the entire surface of the X-ray detector 11 (including the area where the X-rays are blocked by the aperture blades 13a).

[0122] (Step S304) The image processing device 20 receives the position of the aperture blade 13a of the variable aperture 13 from the system control device 16, and calculates, from the position of the aperture blade 13a, an area A (field of view range 11a) that is not blocked by the aperture blade 13a in the image after processing in step S104.

[0123] Alternatively, in the X-ray image after processing in step S104, the peripheral portion of the image where the detected X-ray value is low is extracted by image processing such as binarization processing, and the area A (field of view range 11a) that is not blocked by the aperture blades 13a is calculated based on the X-ray image.

[0124] (Step S305) In step S303, the image processing device 20 receives information on whether the full-screen view enlargement button (not shown) of the operation device 15 is on, which is received by the system control device 16. If the full-screen view enlargement button is on, the image processing device 20 proceeds to step S307. If the full-screen view enlargement button is off, the image processing device 20 proceeds to step S306.

[0125] (Step S306) If the field of view full screen enlargement button is off, the image processing device 20 cuts out the entire field of view size selected by the field of view size selection button 15a received in step S301 as area A (field of view range 11a) from the X-ray image processed in step S104.

[0126] When the aperture lever 15b is operated, the extracted image includes a peripheral region where the X-ray detection value is low and which is shielded by the aperture blades 13a.

[0127] The X-ray image of the cut-out region A (field of view range 11 a ) is stored in the display image memory 22 .

[0128] (Step S307) If the field of view full screen enlargement button is on, the image processing device 20 cuts out the X-ray image of the area A (field of view range 11a) not blocked by the diaphragm blades 13a calculated in step S304 from the X-ray image processed in step A104.

[0129] The cut-out image does not include the peripheral region where the X-ray detection value is low and is shielded by the aperture blades 13a.

[0130] The X-ray image of the cut-out region A (field of view range 11 a ) is stored in the display image memory 22 .

[0131] (Step S308) The image processing device 20 calculates the magnification ratio for enlarging the image of the area A (field of view 11a) cut out in step S306 or S307 to a display image B of a predetermined size to be displayed on the image display device .

[0132] In the third embodiment, since the aspect ratio of area A (field of view range 11a) may not be 1, the magnification ratio is calculated by dividing the number of pixels on the long side of area A by the number of pixels on the corresponding side of display image B.

[0133] Furthermore, the image processing device 20 determines whether the calculated magnification rate is greater than a predetermined value L, and if the magnification rate is greater than the predetermined threshold value L, the process proceeds to step S109. On the other hand, if the magnification rate is equal to or less than the threshold value L, the process proceeds to step S108. The determination result is stored in the display image memory 22 in association with the X-ray image of the cut-out area A (field of view range 11a).

[0134] (Step S108) When the magnification ratio is equal to or less than a predetermined threshold value L, the image interpolation device 21 performs a second high-resolution process (e.g., a general interpolation process that does not use a learning model such as the widely known Bicubic process) that requires a short calculation time, as in step S108 of the first embodiment, to enlarge the X-ray image of the area A (field of view range 11a) cut out in step S106 to the size of the display image B (display image 23a) while increasing the resolution.

[0135] (Step S109) On the other hand, if the magnification ratio of the image of area A (field of view range 11a) stored in display image memory 22 is greater than a predetermined threshold L, in step S109, the image interpolation device 21 performs a first high-resolution process (e.g., super-resolution process using a learning model) that requires a long calculation time but can achieve high-definition resolution, and enlarges the X-ray image of area A (field of view range 11a) cut out in step S106 to the size of display image B (display image 23a) while increasing its resolution.

[0136] (Step S309) If the enlarged image generated in step S108 or S109 is not a square (aspect ratio of 1), image interpolation device 21 adds black pixels to the periphery to generate a square display image 23a.

[0137] (Step S110) The image interpolation device 21 causes the image display device 23 to display the generated display image 23a.

[0138] The above steps S101 to S110 are repeated at a predetermined frame rate until the operation device 15 receives an end instruction from the operator, thereby displaying a perspective image (moving image) on the image display device .

[0139] A further explanation will be given using a specific example shown in FIGS. 7(a) to (c).

[0140] 7(a), the size of the display image 23a is predetermined to be 1000×1000 pixels in length×width. The threshold value of the magnification ratio is set to L=3.

[0141] As shown in FIG. 2(a), in step S101, if the operator presses the B2 button of the field of view size selection button 15a, positions the aperture blade 13a at a position where the field of view range 11a is 500 x 500 pixels in height x width, and does not operate the aperture lever 15b (i.e., fully open), then area A (field of view range 11a) is 500 x 500 pixels.

[0142] Because the aperture lever 15b has not been operated, the unapertured area A (field of view range 11a) cut out in step S307 is 500 x 500 pixels in height x width. Also, the entire field of view size B2 selected with the field of view size selection button, cut out in step S306, is also 500 x 500 pixels in height x width.

[0143] Therefore, whether the full-screen view enlargement button is ON or OFF, the area A (viewing range 11a) is 500×500 pixels in height×width.

[0144] The magnification ratio for enlarging area A (field of view range 11a) to the size of display image B (display image 23a) is B / A=1000 / 500=2, which is less than or equal to threshold L=3, so image interpolation device 21 enlarges the image to the size of display image B (display image 23a) while increasing the resolution using a second high-resolution processing (e.g., bicubic processing) which has a short calculation time.

[0145] Next, in both Figures 7(b) and (c), in step S101, the operator presses the B2 button of the field of view size selection button 15a, positions the aperture blade 13a at a position where the field of view range 11a is 500 x 500 pixels in height x width, and then operates the aperture lever 15b to narrow the field of view range and set the field of view range 11a to 150 x 200 pixels in height x width.

[0146] In this case, the undiaphragmed area A cut out in step S307 is 150 x 200 pixels in height x width, but the entire area cut out in step S306 with field of view size B2 selected with the field of view size selection button is 500 x 500 pixels in height x width, so the sizes are different. In other words, the image displayed will differ depending on whether the field of view full screen enlargement button is ON or OFF.

[0147] If the full-screen field of view enlargement button is ON, an enlarged image of the field of view 11a (not including the aperture) extracted in step S307 is generated, as shown in FIG. 7(c). The enlargement ratio calculated in step S308 is the ratio that makes the long side of the field of view 11a (length × width = 150 × 200 pixels) equal to the number of pixels of the corresponding side of the display image B, i.e., B / A = 1000 / 200 = 5. Because the enlargement ratio of 5x is greater than the enlargement ratio threshold L (= 3), the image interpolation device 21 enlarges the X-ray image of the 150 × 200 pixel field of view 11a by a 5x magnification using a first resolution enhancement process (e.g., super-resolution processing using a learning model), which requires a long calculation time but produces a high-resolution image (step S109). The short side is enlarged to 1000 pixels by adding black pixels to the periphery or by displaying the image of the area blocked by the aperture sent from the detector as is (step S309).

[0148] If the field of view full screen enlargement button is ON, when cutting out the image of the field of view range 11a not including the diaphragm in step S307, it is also possible to use a method of cutting it into a square image including the area blocked by the diaphragm.

[0149] The image enlarged to the size of display image 23a is displayed on image display device 23, as shown in Fig. 7(c). As is clear from Fig. 7(c), display image 23a is displayed with its long side enlarged to fill the entire screen.

[0150] On the other hand, if the field of view full-screen enlargement button is OFF, an enlarged image of the entire area A image of the field of view size B2 selected with the field of view size selection button 15a, which was extracted in step S306, is generated, as shown in FIG. 7(b). This image includes an area where X-rays are blocked by the diaphragm blades 13a at the periphery. The enlargement ratio calculated in step S308 is B / A = 1000 / 500 = 2, since area A is 500 x 500 pixels long and the enlargement ratio for making its long side match the number of pixels of the corresponding side of the display image B. Because the enlargement ratio of 2 is smaller than the enlargement ratio threshold L (= 3), the image interpolation device 21 performs a second high-resolution process (e.g., bicubic process) that requires a shorter calculation time, enlarging the image while increasing the resolution at a magnification ratio of 2 (step S108).

[0151] The enlarged display image 23a is displayed on the image display device 23. This image is displayed including an area in the periphery where X-rays are blocked by the aperture blades 13a.

[0152] As described above, in the third embodiment, in addition to the field of view size selection button 15a, the aperture lever 15b can be used to select whether or not to display the field of view in full screen, even when the position of the aperture blades 13a is adjusted to the desired aspect ratio.

[0153] Furthermore, because the first or second resolution enhancement process is performed according to the magnification ratio of the field of view 11a to the display image 23a, the high-resolution display image 23a can be displayed as a fluoroscopic image in real time without reducing the image resolution. During fluoroscopic examinations, the area of ​​interest is often narrowed to prevent image quality degradation and increased radiation exposure due to scattered radiation. This method makes it possible to magnify the area of ​​interest to the entire screen in high resolution in real time. Furthermore, while binning is generally not performed on the detector when observing a narrow area with fluoroscopy, the present method makes it possible to perform binning, i.e., to perform fluoroscopy with a low dose, and to magnify and observe the desired area with high resolution.

[0154] <<Embodiment 4>> The X-ray fluoroscopic imaging apparatus of the fourth embodiment will be described with reference to Fig. 9 and Fig. 10. Fig. 9 is a diagram for explaining the display screen of the apparatus of the fourth embodiment, and Fig. 9 is a flowchart showing the operation of the apparatus of the first embodiment.

[0155] The X-ray fluoroscopic imaging device of embodiment 4 has the same configuration as the device of embodiment 1, but while a display image 23a processed by a first high-resolution processing (e.g., super-resolution using a learning model), which takes a long time to calculate, is displayed on the image display device 23, a predetermined display (icon, mark, character, image, etc.) 23b informing the operator of this is displayed on the image display device 23 as shown in Figures 9(c) and (d).

[0156] Specifically, after step S109, the X-ray fluoroscopic imaging device of embodiment 4 displays, on the image display device 23b in step S401, a predetermined display (icon, mark, character, image, etc.) 23b informing the operator that the displayed image 23a has been processed by the first high-resolution processing, which takes a long time to calculate.

[0157] When super-resolution technology using a learning model is used as the first resolution enhancement process, which requires a long calculation time, the processed image can be said to be artificially generated in a sense. Therefore, it cannot be said that there is no possibility that an image different from the actual state of the subject will be displayed. Therefore, by displaying a predetermined display (icon, etc.) 23b as in the fourth embodiment, it is possible to alert the user that super-resolution technology using a learning model is being used.

[0158] The steps other than step S401 in the flow of Fig. 10 are the same as those in the flow of Fig. 3 of embodiment 1. In addition, in the drawing of Fig. 9, the explanation contents other than the predetermined display (icon, etc.) 23b are the same as those in Fig. 2 of embodiment 1. Furthermore, the configuration of the X-ray fluoroscopic imaging apparatus of embodiment 4 is the same as that of the apparatus of embodiment 1. [Explanation of symbols]

[0159] 10 X-ray tube 11 X-ray detector 12 Top plate 11a Field of view 13a aperture blades 13b Drive unit 14 High voltage generator 15 Controller 15a Field of view size selection button 15b Aperture lever 16 System Control Unit 17 Mechanism control device 20 Image processing device 21 Image Interpolator 22 Display image memory 23 Image display devices 23a Display image 25 Subjects

Claims

1. The apparatus includes a tabletop on which an object is placed, an X-ray tube that irradiates the object with X-rays, a movable diaphragm, a flat X-ray detector, an image processing device, and an image interpolation device, the movable diaphragm includes diaphragm blades arranged between the subject and the X-ray tube and a drive unit that changes the position of the diaphragm blades, and adjusts an irradiation area of ​​the X-rays irradiated from the X-ray tube; the X-ray detector detects X-rays that have passed through the subject and reached the subject; the image processing device generates an X-ray image from the output of the X-ray detector, determines a field of view corresponding to the irradiation area in the X-ray image based on the position of the diaphragm blades acquired from the drive unit or the X-ray image, and calculates an enlargement ratio for enlarging the field of view to a display image of a predetermined size; When the magnification ratio is greater than a predetermined value, the image interpolation device performs a first resolution enhancement process to enhance the resolution of the X-ray image of the field of view, enlarging the image to the size of the display image at the magnification ratio, and when the magnification ratio is equal to or less than the predetermined value, performs a second resolution enhancement process to enhance the resolution of the X-ray image of the field of view, the second resolution enhancement process having a shorter processing time than the first resolution enhancement process, enlarging the image to the size of the display image at the magnification ratio. An X-ray fluoroscopic imaging device characterized by:

2. 2. The X-ray fluoroscopic imaging device according to claim 1, wherein the first high-resolution processing is a high-resolution processing that uses a learning model, and the second high-resolution processing is a high-resolution processing that does not use a learning model.

3. 2. The X-ray fluoroscopic imaging apparatus according to claim 1, further comprising an operation device that accepts a setting of the size of the field of view area from a user.

4. 2. The X-ray radiography apparatus according to claim 1, wherein the X-ray detector comprises a plurality of X-ray detection elements arranged vertically and horizontally, and a circuit for performing binning processing to bundle detection values ​​of a predetermined number of adjacent X-ray detection elements into an output of one pixel, The image processing device, when determining the field of view corresponding to the irradiation area, determines the number of pixels in the field of view after binning processing, and calculates, as the magnification ratio, a magnification ratio by which the number of pixels in the field of view is enlarged to the number of pixels of the display image.

5. 4. The X-ray radiography apparatus according to claim 3, wherein the operation device comprises a field of view size selection button for selecting a setting of the size of the field of view area from a plurality of predetermined field of view sizes, and an aperture lever for further adjusting the field of view area within the range of the selected field of view size after the field of view size is selected by the field of view size selection button, An X-ray fluoroscopic imaging device, wherein a drive unit for the movable diaphragm positions the diaphragm blades at a position in the field of view area set by the field of view size selection button and the diaphragm lever.

6. 6. The X-ray radiography apparatus according to claim 5, wherein the operation device further comprises a full-screen enlargement button for selecting whether or not to enlarge the X-ray image of the field of view to full screen, When the field of view full screen enlargement button is on, the image processing device calculates, as the enlargement rate, an enlargement rate for enlarging the long side of the field of view set by the aperture lever to the number of pixels of the corresponding side of the displayed image; An X-ray fluoroscopic imaging device characterized in that, when the field of view full screen expansion button is off, the image processing device calculates the magnification rate as the magnification rate for expanding the field of view area selected by the field of view size selection button to the size of the display image.

7. 7. The X-ray radiography imaging device according to claim 6, wherein the aperture lever of the operation device can arbitrarily set the aspect ratio of the field of view area, An X-ray fluoroscopic imaging device characterized in that, when the aspect ratio of the field of view area is different from the aspect ratio of the display image and the field of view full screen expansion button is on, the image interpolation device expands the X-ray image of the field of view area by the magnification ratio and then adds black pixels to the periphery of the short side to generate an image the size of the display image.

8. 2. The X-ray fluoroscopic imaging device according to claim 1, wherein when the display image is enlarged by the first high-resolution processing, the image interpolation device displays a predetermined message indicating this on an image display device together with the display image.

9. 1. An image generating method for an X-ray fluoroscopic imaging device having an X-ray detector and a movable diaphragm for adjusting an X-ray irradiation area, comprising: generating an X-ray image from the output of the X-ray detector; determining a field of view area corresponding to the irradiation area in the X-ray image based on the position of the aperture blades of the movable aperture or the X-ray image; calculating a magnification ratio for enlarging the viewing area to a display image of a predetermined size; If the magnification ratio is greater than a predetermined value, the X-ray image of the field of view is enlarged to the size of the display image at the magnification ratio while increasing the resolution by a first resolution enhancement process, and if the magnification ratio is equal to or less than the predetermined value, the X-ray image of the field of view is enlarged to the size of the display image at the magnification ratio while increasing the resolution by a second resolution enhancement process having a processing time shorter than that of the first resolution enhancement process.

10. An image generating method for an X-ray fluoroscopic imaging apparatus comprising:

Images