JP2012075782A - X-ray image capture device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the operability of switching between the entire image capture and a partial image capture.SOLUTION: An X-ray image capture device according to the present embodiment includes: an X-ray source 1; an X-ray detector 5; an X-ray diaphragm 3 with a variable aperture for limiting irradiation field of the X-ray irradiated from the X-ray source to a subject; a foot switch unit 20 for selecting any one of at least first and second states; and an image capture controller 9 that controls the X-ray irradiation and the X-ray diaphragm so as to radiate the X-ray to the subject in a first irradiation field during the first state and controls the X-ray irradiation and the X-ray diaphragm so as to radiate the X-ray to the subject in a second irradiation field narrower than the first irradiation field during the second state.

Description

  Embodiments described herein relate generally to an X-ray imaging apparatus.

  In treatment under fluoroscopy such as catheterization, long-time X-ray irradiation is required. For this reason, there are contrivances such as protection by a protective plate and reduction of the imaging rate, but the exposure reduction effect is not sufficient.

  On the other hand, a technique called ROI imaging is known. This is to perform X-ray imaging limited to a partial region designated by the operator. However, switching between full-surface imaging and partial imaging (also referred to as ROI imaging) can be performed together with a switching instruction operation, an X-ray aperture opening adjustment operation, and an X-ray irradiation instruction operation when the operation is completed. In addition, when returning from partial imaging to full imaging, a troublesome operation is required as well, and there is a problem that it is difficult to use clinically.

JP-A-6-47034 JP-A-8-266535 JP 2003-116845 A

  The purpose is to improve the operability related to the mutual switching between full-surface imaging and partial imaging.

  An X-ray imaging apparatus according to the present embodiment includes an X-ray source, an X-ray detector that is disposed to face the X-ray source and detects X-rays that have passed through a subject, and the X-ray source from the subject. In order to limit the irradiation field of X-rays irradiated to the specimen, an X-ray aperture with variable aperture, a switch unit that can be selectively operated from one of the first and second states, and the first state are maintained. The X-ray irradiation from the X-ray source and the X-ray diaphragm are controlled so that the subject is irradiated with the X-ray in the first irradiation field during the period, and the second state is maintained. An imaging control unit that controls X-ray irradiation from the X-ray source and the X-ray diaphragm so that the subject is irradiated with the X-ray in a second irradiation field that is narrower than the first irradiation field during a certain period It comprises.

It is a figure which shows the structure of the X-ray imaging device which concerns on this embodiment. It is a figure which shows the structural example of the imaging mechanism containing the X-ray source of FIG. It is a figure which shows the possible shielding board with which the X-ray diaphragm of FIG. 1 is equipped. It is a figure which shows the structural example of the foot switch unit of FIG. It is a figure which shows the other structural example of the foot switch unit of FIG. It is a figure which shows the further another structural example of the foot switch unit of FIG. It is a flowchart which shows the procedure of the imaging process by the imaging control part of FIG. It is a figure which shows the example of a display of S05 of FIG. 7, S16. It is a flowchart which shows the other procedure of the imaging process by the imaging control part of FIG. It is a flowchart which shows the other procedure of the imaging process by the imaging control part of FIG. It is a flowchart which shows the other procedure of the imaging process by the imaging control part of FIG. It is a flowchart which shows the procedure of the update process of the ROI position by the image process part of FIG. 1, and an imaging control part. 7 is a flowchart illustrating another procedure of ROI position update processing by the image processing unit and the imaging control unit of FIG. 1. It is a figure which shows the structural example of a biplane type X-ray imaging device. It is a figure which shows an example of the foot switch unit applied to the biplane type | mold X-ray imaging device which concerns on this embodiment. FIG. 16 is a diagram illustrating an example of image display corresponding to pressing of a full-surface imaging (F / L) switch 74 in FIG. 15. FIG. 16 is a diagram illustrating an example of image display corresponding to pressing of a partial imaging (F / L) switch 75 in FIG. 15.

The X-ray imaging apparatus according to this embodiment will be described below with reference to the drawings.
As shown in FIGS. 1 and 2, the X-ray source 1 is attached to one end of a C-arm 31. The C-arm 31 is supported by the ceiling suspension arm 32 and the slider 33 so as to be individually rotatable with respect to three orthogonal axes (X, Y, Z) intersecting at an imaging fixing point (isocenter). The X-ray detector 5 is attached to the other end of the C arm 31. The X-ray detector 5 faces the X-ray source 1. The X-ray detector 5 may be a combination structure of an image intensifier and a TV camera, or a plurality of detection elements (pixels) that directly or indirectly convert incident X-rays into charges are arranged in a two-dimensional manner. It may be a flat detector (flat panel detector). When imaging, the subject is placed between the X-ray source 1 and the X-ray detector 5 while being placed on the couch top.

  The X-ray source 1 is connected to a high voltage generator 2. The high voltage generator 2 applies a high voltage (tube voltage) between the cathode and anode of the X-ray source 1. The high voltage generator 2 supplies a current (filament current) to the filament of the X-ray source 1. Thereby, X-rays are generated from the X-ray source 1. The tube voltage and filament current of the high voltage generator 2 are individually variable. The imaging control unit 9 supplies the first and second control signals to the high voltage generator 2. The tube voltage applied to the X-ray source 1 by the high voltage generator 2 is changed by the first control signal. The filament current supplied from the high voltage generator 2 to the X-ray source 1 is changed by the second control signal. Changes in the tube voltage and the filament current change the dose of X-rays irradiated to the subject.

  An X-ray stop 3 is mounted on the X-ray emission window of the X-ray source 1. The X-ray diaphragm 3 limits the X-ray irradiation field irradiated from the X-ray source 1 to the subject. As shown in FIG. 3, the X-ray diaphragm 3 includes a plurality of individually movable shielding plates 14 to 17. The X-ray irradiation field is limited to a rectangle, a rectangle inclined with respect to the X axis, or a circle depending on the number of the shielding plates 14 to 17 and the variation of the moving method. Here, for convenience of explanation, it is assumed that there are four shielding plates 14 to 17 and the X-ray irradiation field is rectangular. The shielding plates 14 to 17 are typically lead plates having X-ray shielding properties. The shielding plates 14 to 17 may be essentially wedges having translucency with respect to X-rays for changing the quality of X-rays, for example, molybdenum-containing plates. The diaphragm control unit 10 individually controls the movement of the shielding plates 14 to 17 provided in the X-ray diaphragm 3. Thereby, the center position of the opening surrounded by the shielding plates 14 to 17 and the size of the opening, for example, the diagonal length and diameter of the opening can be arbitrarily changed.

  Note that imaging in which X-rays are irradiated while being limited to a part of the light receiving surface of the X-ray detector 5 is referred to as partial imaging or ROI imaging. ROI is an abbreviation of Region of Interest, that is, a region of interest that can be defined as a partial region within an imaging region that is being watched with high interest. The irradiation field at this time is referred to as a second irradiation field. The irradiation field is typically defined as the size of the region where the X-ray flux intersects the imaging reference plane that passes through the isocenter and is orthogonal to the X-ray central axis. An opening corresponding to the second irradiation field is referred to as a partial opening. An irradiation field wider than the second irradiation field is referred to as a first irradiation field. Typically, the first irradiation field corresponds to the entire light receiving surface of the X-ray detector 5. Here, the first irradiation field will be described as an area corresponding to the entire light receiving surface of the X-ray detector 5, but if it is wider than the second irradiation field, it may be an area narrower than the area corresponding to the entire light receiving surface. good. Imaging in the first irradiation field is called full-surface imaging. The opening corresponding to the first irradiation field is referred to as a full surface opening. The center position and the size of the second irradiation field in the first irradiation field are arbitrarily variable under the control of the aperture control unit 10.

  The image storage unit 8 stores image data captured by the X-ray detector 5. The electrocardiogram waveform measuring device (ECG) 6 measures the electrocardiogram waveform of the subject, analyzes the electrocardiogram waveform, and outputs data representing the heartbeat time phase. The heartbeat time phase is, for example, an index obtained by normalizing each position in a period (one heartbeat period) from an R wave to the next R wave. The image data stored in the image storage unit 8 is individually associated with heartbeat time phase data corresponding to the imaging time. The image data stored in the image storage unit 8 is displayed on the monitor 13 via the image processing unit 11. The monitor 13 is installed in the catheter treatment room, for example, together with the imaging mechanism shown in FIG.

  A foot switch unit 20 is disposed on the floor of the catheter treatment room. The foot switch unit 20 is provided for instructing the start and end of X-ray imaging accompanied by X-ray irradiation by a stepping operation with a foot by a doctor who is performing catheter treatment. The foot switch unit 20 is configured to be able to selectively transition from the neutral state to the first state or the second state. Typically, as shown in FIG. 4, the foot switch unit 20 is equipped with first and second types of foot switches 21 and 22. Of course, the foot switch unit 20 may have a switch in addition to the foot switches 21 and 22. When the first foot switch 21 is stepped on, the first state is selected in the switch box 25. When the second foot switch 22 is stepped on, the switch box 25 selects the second state. When neither the first foot switch 21 nor the second foot switch 22 is depressed, the switch box 25 selects a neutral state that is neither the first nor the second.

  The foot switch unit 20 is not limited to the structure in which the first and second types of foot switches 21 and 22 are provided as long as the first and second states can be selected. For example, as shown in FIG. 5, when a single foot switch 23 is provided and the foot switch 23 is fully depressed to the lowest position (when fully depressed), the switch box 25 selects the first state. When the foot switch 23 is depressed halfway (half-pressed), the switch box 25 selects the second state. When the foot switch 23 is released and returned to the top, the neutral state is selected. Further, as shown in FIG. 6, the foot switch unit 20 may have a single seesaw type switch 24. When the seesaw switch 24 is tilted to the left, the switch box 25 selects the first state, and when the seesaw switch 24 is tilted to the right, the switch box 25 selects the second state. When the foot switch 24 is released and returned to the horizontal position, the neutral state is selected. The structure of the foot switch unit 20 is arbitrary as long as it has an equivalent function. Here, the foot switch unit 20 equipped with the first and second types of foot switches 21 and 22 shown in FIG. 4 will be described as an example.

  The imaging control unit 9 controls the high voltage generation unit 2 to irradiate X-rays in order to perform full-surface imaging during the period when the first foot switch 21 of the foot switch unit 20 is continuously depressed. At the same time, the aperture is fully opened by controlling the X-ray diaphragm 3. In addition, the imaging control unit 9 controls the high voltage generation unit 2 to perform X-rays in order to execute partial imaging during a period when the second foot switch 22 of the foot switch unit 20 is continuously depressed. At the same time, the X-ray diaphragm 3 is controlled to narrow the aperture narrowly. With a single operation of any of the first and second foot switches 21 and 22, X-ray irradiation can instantaneously switch between full-surface imaging and partial imaging with an aperture change. With the recent development of endovascular treatment, the X-ray irradiation time has become longer. Although the reduction of exposure is required from the clinical site, switching between partial imaging and full imaging by a single operation in this way shortens the treatment time, and accordingly reduces the amount of contrast medium injection, and above all, exposure. Reduction can be realized.

  With reference to FIG. 7, the operation procedure of full-surface imaging and partial imaging will be described in detail. Initially, the opening of the X-ray diaphragm 3 is provided in a fully open state. The imaging control unit 9 waits for the first foot switch 21 to be stepped on by the doctor as shown on the left side of FIG. 8 in a timely manner after starting the procedure (S01). With this as a trigger, the imaging control unit 9 controls the high voltage generation unit 2 to start X-ray generation and irradiate the subject with X-rays (S02). The subject is irradiated with X-rays in the first irradiation field. X-ray irradiation is continued until the foot is released from the first foot switch 21 (S07) and the state returns to the neutral state. During the period in which the X-ray irradiation is continued, image data is repeatedly acquired by the X-ray detector 5 at a constant cycle (S03). The acquired image data is stored in the image storage unit 8 (S04) and displayed live on the monitor 13 via the image processing unit 11 (S05). The image data is stored in association with heartbeat phase data corresponding to each image. While the first foot switch 21 is being depressed, the opening of the X-ray diaphragm 3 is fully open, so that full-surface imaging is repeatedly performed and displayed on the monitor 13 as a moving image.

  The image acquisition (S03) -image display (S05) process is repeated until the first foot switch 21 is released (S06). When the foot is released from the first foot switch 21 (S06), the imaging controller 9 controls the high voltage generator 2 to stop the generation of X-rays and stop the X-ray irradiation (S07). Thereby, the whole surface imaging is stopped. When the entire imaging is stopped, the imaging control unit 9 controls the image storage unit 8 and the image processing unit 11 to hold the display of the entire image acquired at the end of the entire imaging period on the monitor 13 (so-called last processing). Image hold function). When an instruction to end the examination / surgical procedure is not input (S08), the imaging control unit 9 takes either the first or second foot switch 21 or 22 from the neutral state by stepping on one of the first and second foot switches 21 and 22. Wait for transition to any state.

  Next, the operator designates, for example, the tip position of the catheter as a point of interest on the entire image displayed and held on the monitor 13 via the ROI setting operation unit 12 having a mouse or the like. After that, when the doctor steps on the second foot switch 22 to change to the on state (S11), using this as a trigger, the imaging control unit 9 causes the aperture control unit 10 to have a predetermined size centered on the point of interest. A region of interest (ROI) range information is supplied along with a control signal for initiating an aperture change. In response to this control signal, the diaphragm control unit 10 starts moving the diaphragms 14 to 17 as shown on the right side of FIG. 3 in order to change the aperture of the diaphragm 3 from the full aperture to the partial aperture corresponding to the ROI (S12). When the partial opening corresponding to the ROI is secured, the movements of the apertures 14 to 17 are stopped.

  In synchronization with the start of aperture change, the imaging control unit 9 controls the high voltage generation unit 2 to start X-ray generation and start irradiating the subject with X-rays (S13). As described above, when the second foot switch 22 is turned on, the opening change is started, and at the same time, X-ray irradiation is started. In other words, it is a stage before a partial opening corresponding to the ROI is secured, and X-ray irradiation is started after the second foot switch 22 is stepped on so that a live image can be visually recognized. There is no need to wait for confirmation of the live image until the partial opening corresponding to the ROI is secured after the second foot switch 22 is depressed.

  The X-ray field is gradually narrowed from the first field corresponding to the entire surface, and finally the subject is irradiated in the second field. In synchronization with the start of X-ray irradiation, acquisition of image data by the X-ray detector 5 is started (S14). The acquired partial image data is displayed live as a moving image on the monitor 13 via the image storage unit 8 and the image processing unit 11 (S16).

  As shown on the right side of FIG. 8, the partial image displayed live is synthesized and superimposed on the entire image acquired and stored in the immediately preceding entire imaging period, as shown on the right side of FIG. superimpose) (S15). Even when the aperture of the diaphragm 3 is changing from the full aperture to the partial aperture corresponding to the ROI, the image processing unit 11 trims the image (partial image) in the range corresponding to the ROI, and the entire surface. It is superimposed on the image. The entire image combined with the partial image may be a reproduced moving image, or a specific one-frame still image among a plurality of still images constituting the moving image, for example, the last frame still image in the immediately preceding entire imaging period. It may be. When synthesizing the reproduced full image with the partial image, it is preferable to reproduce the full image with heartbeat synchronization. The heartbeat phase of the whole image can be matched with the heartbeat phase of the live partial image by the heartbeat synchronization reproduction.

  At the time of partial imaging, the imaging control unit 9 supplies information related to the position and size of the region of interest to an automatic exposure control unit (ABC) 7. The automatic exposure control unit 7 extracts data corresponding to the region of interest from the output of the detector 5, compares an average value representing the exposure amount with a threshold value, and supplies the comparison result to the imaging control unit 9.

  The image acquisition (S14) -image display (S16) process is repeated until the second foot switch 22 is released (S17). When the foot is released from the second foot switch 22 (S17), the imaging controller 9 controls the high voltage generator 2 to stop the generation of X-rays and stop the X-ray irradiation (S18). Thereby, partial imaging is stopped. When the partial imaging is stopped, the imaging control unit 9 displays the image storage unit 8 and the image processing unit 11 in order to display and hold the partial image acquired at the end of the partial imaging period on the monitor 13 together with the entire image combined therewith. Control.

  Further, when the partial imaging is stopped, the imaging control unit 9 controls the aperture control unit 10 to automatically return the aperture of the aperture 3 from the partial aperture to the full aperture (S19). By this automatic return, the entire image can be acquired immediately after the first foot switch 21 is turned on. However, as shown in FIG. 9, the procedure for automatically returning the aperture of the diaphragm 3 from the full aperture to the partial aperture immediately after the completion of the full imaging is not denied (S20). Further, as shown in FIG. 10, immediately after the end of the partial imaging and the entire imaging, the procedure for not automatically changing the aperture is not denied (S20). In the example of FIG. 10, when full-surface imaging is repeated intermittently or when partial imaging is intermittently repeated, an image of a necessary irradiation field at a necessary opening can be acquired immediately.

  The doctor moves the catheter as the procedure progresses. The region of interest is moved to the moved region, and the point of interest (region of interest) is changed as needed. Further, the doctor can press the first foot switch 21 at an arbitrary timing. At this time, the diaphragm is fully opened, X-rays are irradiated on the entire surface of the detector, and X-ray images of the entire surface are collected and displayed.

  As described above, when the point of interest is designated on the entire image by the doctor via the mouse or the touch panel, the region of interest is set with a predetermined size around the point of interest. However, the position and size of the region of interest may be defaulted (preset) to omit the point of interest specification. Further, instead of designating a point of interest via a mouse or touch panel, the operator may designate using a remote control remote controller such as a laser point. The size of the region of interest can be arbitrarily changed according to the operator's instruction. Furthermore, a plurality of region of interest candidates may be prepared in advance in a grid pattern for the entire range of the entire image, and the operator may select one of these candidates.

  Further, the image processing unit 11 processes the contrast image to automatically extract shapes similar to the object of interest specified in advance, such as the catheter tip, stent, guide wire tip, and pulmonary vein entrance, and at the position and size for accommodating them. A region of interest candidate may be generated and displayed as a frame line on the entire image, and the operator may be prompted to determine whether it is possible. In this case, in the case of a technique using a plurality of catheters, a plurality of catheter tip tips are automatically extracted to generate a plurality of region of interest candidates, and a single region of interest is selected from the plurality of region of interest candidates. May be prompted to the operator. Furthermore, as a method for automating the selection of the only region of interest, a pulmonary vein may be identified from another type of modality image, for example, a CT image, and the closest region of interest candidate may be automatically selected as the only region of interest. Specifying on the moving image instead of specifying the point of interest on the single held whole image is advantageous in that the visual field is not missed even in a moving organ. The position and size of the region of interest used in the past may be reproduced.

  As shown in FIG. 11, when the second foot switch 22 is pressed, the imaging control unit 9 determines whether or not the ROI has been set (S21). When the ROI has been set, the imaging control unit 9 starts partial imaging. When the ROI is not set, full-surface imaging is executed.

  FIG. 12 shows an automatic update process procedure of the region of interest by the image processing unit 11. Extract partial images corresponding to the ROI from the entire image when the ROI is set and the current entire image (S31, S33), extract the catheter image from each, binarize (S32, S34), The similarity is calculated (S35). The similarity is calculated, for example, as a sum of absolute values of differences. The similarity is compared with a predetermined threshold (S36), and when the similarity is higher than the threshold, that is, when the displacement of the catheter image is small, it is determined that ROI resetting is unnecessary (S37). When the similarity is less than the threshold value, that is, when the displacement of the catheter image is large, it is determined that the ROI needs to be reset, and a warning message indicating that the deviation of the ROI with respect to the catheter is large is displayed on the monitor 13 (S38); The direction in which the degree of similarity increases is calculated (S39), and the ROI is automatically reset to a position where the degree of similarity is higher than the threshold (S40). As shown in FIG. 13, when the similarity is low, a full-surface image is newly acquired (S41), and the binary value related to the catheter is moved while moving the ROI within a predetermined search range with respect to the new full-surface image. An image is generated, and an ROI position where the similarity with the binary image related to the catheter derived from the entire image when the ROI is set has the maximum value is searched (S42). The searched ROI is determined as a new ROI (S43).

  The full image pickup and the partial image pickup may be performed under the same image pickup conditions, but may be made different by the image pickup control unit 9 as follows. Since the total exposure only needs to be lower than that during full-surface imaging, the X-ray dose in partial imaging may be increased from that during full-surface imaging. In partial imaging, the amount of scattered radiation decreases, so it is a little darker than in full-surface imaging. Therefore, the dose is increased by increasing at least one of the tube current, tube voltage, and X-ray pulse width than that of full-surface imaging. Alternatively, the X-ray condition may be changed, and the gain at the time of partial imaging may be made higher than that for full-surface imaging to brighten the image. Further, since only the catheter needs to be visible during partial imaging, the tube voltage is increased, the tube current and the pulse width are decreased, or the filter is changed to a harder wire quality to reduce exposure. Image processing conditions such as compensating for scattered line segments and increasing image gain may be made different between full image capture and partial image capture.

  As a partial image display method, the partial image is displayed so as to overlap the entire image in the above description. However, only the partial image may be displayed and the shielded area may be displayed in black. Alternatively, only the partial image may be enlarged and displayed up to the same matrix size as the entire image. Further, when displaying the partial image so as to be superimposed on the entire image, one of the images may be displayed with black and white reversed. Furthermore, when the partial image is displayed so as to be superimposed on the entire image, the partial image may be displayed in a translucent manner.

  In the above description, it has been described that the partial imaging is completed when the second foot switch 22 is released. However, when the movement of the C arm 31 is detected, the partial imaging is automatically terminated and automatically switched to the full imaging. It may be. When the C-arm 31 is returned to the original position before the movement, the original region of interest before the movement is reproduced.

  The technical idea of switching between full surface imaging and partial imaging with a single operation with X-ray irradiation and aperture change can be applied not only to the single plane type described above but also to the biplane type shown in FIG. As is well known, a biplane type X-ray diagnostic apparatus is an apparatus capable of imaging from two directions of a front surface (frontal) and a side surface (lateral) with respect to a subject placed on its top on its back. FIG. 15 illustrates a foot switch unit 71 suitable for a biplane type X-ray diagnostic apparatus. When the foot switch 72 is operated to be in the ON state, the entire imaging on the side surface is not executed, and the entire imaging on the front side is executed. When the foot switch 73 is operated to be in the on state, the entire image on the front side is not executed, and the entire image on the side surface is executed. When the foot switch 74 disposed between the foot switches 72 and 73 is operated to be in the ON state, as shown in FIG. 16, both of the side surface full surface imaging and the front side full surface imaging are executed. For example, a foot switch 75 for partial imaging is arranged on the right side of the foot switches 72, 73, and 74 for full-surface imaging. When the foot switch 75 is operated to be in the ON state, as shown in FIG. 17, both of the side-side partial imaging and the front-side partial imaging are executed. In this way, by narrowing down the foot switches that are considered to be frequently used and minimizing the number thereof, erroneous operations can be suppressed and operability can be improved.

  Although several embodiments of the present invention 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, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... X-ray source, 2 ... High voltage generator, 3 ... X-ray aperture, 5 ... X-ray detector, 6 ... Electrocardiogram waveform measuring device (ECG), 7 ... Automatic exposure control part, 8 ... Image storage part, DESCRIPTION OF SYMBOLS 9 ... Imaging control part, 10 ... Aperture control part, 11 ... Image processing part, 13 ... Monitor, 20 ... Foot switch unit, 21 ... 1st foot switch, 22 ... 2nd foot switch

Claims (15)

An X-ray source that emits X-rays;
An X-ray detector disposed opposite to the X-ray source for detecting X-rays transmitted through the subject;
A variable aperture X-ray diaphragm to limit the X-ray field irradiated from the X-ray source to the subject;
A switch unit that can be selectively operated from one of the first and second states to the other;
Controlling X-ray irradiation from the X-ray source and the X-ray diaphragm so as to irradiate the subject with the X-rays in a first irradiation field during a period in which the first state is maintained; The high voltage generator and the X-ray diaphragm are controlled to irradiate the subject with the X-ray in a second irradiation field that is narrower than the first irradiation field during a period in which the second state is maintained. An X-ray imaging apparatus comprising:   The X-ray imaging apparatus according to claim 1, further comprising an image processing unit that synthesizes a second image corresponding to the second irradiation field with a first image corresponding to the first irradiation field.   The image processing unit combines the first image corresponding to the first irradiation field as a moving image or a still image with the second image corresponding to the second irradiation field in a period in which the second state is maintained. The X-ray imaging apparatus according to claim 2.   The image processing unit sets one image processing condition of the first image and the second image to the other image processing so that the luminance level of the first image and the luminance level of the second image are substantially equalized. The X-ray imaging apparatus according to claim 2, wherein the X-ray imaging apparatus is different from the conditions.   2. The X-ray irradiation dose in a period in which the second state is maintained is larger than an X-ray irradiation dose in a period in which the first state is maintained. The X-ray imaging apparatus described.   The tube voltage applied to the X-ray source during the period in which the second state is maintained is higher than the tube voltage applied to the X-ray source during the period in which the first state is maintained. The X-ray imaging apparatus according to claim 1.   2. The X-ray according to claim 1, wherein the first irradiation field corresponds to a substantially full opening of the X-ray diaphragm, and the second irradiation field corresponds to a partial opening of the X-ray diaphragm. Line imaging device.   The imaging control unit opens an opening of the X-ray diaphragm so that the second irradiation field is set to a predetermined position and size when the X-ray source is positioned at a predetermined imaging angle with respect to the subject. The X-ray imaging apparatus according to claim 1, wherein the X-ray imaging apparatus is controlled.   The X-ray imaging apparatus according to claim 1, wherein the second irradiation field is set according to a region of interest designated on the first image.   The imaging control unit controls the opening of the X-ray diaphragm so as to move the position of the second irradiation field in accordance with the position of the image of the region of interest in the second image. 9. The X-ray imaging apparatus according to 9.   When the displacement of the image of the region of interest in the second image exceeds a predetermined distance, the imaging control unit displays a message for prompting the user to switch from the second state to the first state. The X-ray imaging apparatus according to claim 9, wherein a control signal for outputting the combination is output.   The imaging control unit controls the X-ray stop to change the opening of the X-ray stop to an opening corresponding to the first irradiation field when the second state is released. The X-ray imaging apparatus according to claim 1. An X-ray source that emits X-rays;
An X-ray detector disposed opposite to the X-ray source for detecting X-rays transmitted through the subject;
A variable aperture X-ray diaphragm to limit the X-ray field irradiated from the X-ray source to the subject;
A first switch that is turned on / off by an operator;
A second switch that is turned on / off by the operator;
The X-ray irradiation from the X-ray source and the X-ray diaphragm are controlled so as to irradiate the subject with the X-ray in the first irradiation field during a period in which the ON state of the first switch is maintained. Then, the X-ray from the X-ray source is irradiated so that the subject is irradiated with the X-ray in a second irradiation field narrower than the first irradiation field during a period in which the second switch is on. An X-ray imaging apparatus comprising: an imaging control unit that controls X-ray irradiation and the X-ray diaphragm. An X-ray source that emits X-rays;
An X-ray detector disposed opposite to the X-ray source for detecting X-rays transmitted through the subject;
A variable aperture X-ray diaphragm to limit the X-ray field irradiated from the X-ray source to the subject;
A switch that is turned on and off by an operator;
X-ray irradiation from the X-ray source and the X so that the generation of the X-ray is started and the change of the aperture of the X-ray diaphragm is started when the switch is switched from the OFF state to the ON state. An X-ray imaging apparatus comprising: an imaging control unit that controls a line diaphragm. A first X-ray source that emits X-rays;
A first X-ray detector disposed opposite to the first X-ray source for detecting X-rays transmitted through the subject;
A first X-ray diaphragm having a variable aperture for limiting an X-ray field irradiated from the first X-ray source to the subject;
A second X-ray source that emits X-rays;
A second X-ray detector disposed opposite to the second X-ray source for detecting X-rays transmitted through the subject;
A second X-ray diaphragm having a variable aperture for limiting the X-ray field irradiated from the second X-ray source to the subject;
A first switch that is turned on / off by an operator;
A second switch that is turned on / off by the operator;
X-ray irradiation from the first and second X-ray sources and the first so as to irradiate the subject with the X-ray in the first irradiation field during a period in which the first switch is kept on. And controlling the second X-ray aperture so that the subject is irradiated with the X-rays in a second irradiation field narrower than the first irradiation field during a period in which the second switch is kept on. An X-ray imaging apparatus comprising: an imaging control unit that controls X-ray irradiation from the first and second X-ray sources and the first and second X-ray apertures.

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