WO2012111458A1

WO2012111458A1 - X-ray image diagnostic device and image display method

Info

Publication number: WO2012111458A1
Application number: PCT/JP2012/052525
Authority: WO
Inventors: 忍竹之内; 鈴木　克己
Original assignee: 株式会社日立メディコ
Priority date: 2011-02-15
Filing date: 2012-02-03
Publication date: 2012-08-23
Also published as: JPWO2012111458A1; CN103379859B; JP5706452B2; CN103379859A

Abstract

In order to accurately display the head-feet direction on a display unit regardless of the x-ray plane detector insertion direction, an x-ray image diagnostic device is provided with: an x-ray tube (1) for irradiating a test subject with x-rays; a grid (2) for removing a scattered ray component caused by the test subject (20); an x-ray plane detector (3) that detects transmitted x-rays of the test subject (20) and outputs image data, and is positioned so as to face the x-ray tube (1); an image display unit (6) for displaying an image based on image data; a grid stripe direction determination unit (5b) for determining whether the stripe direction originating from the grid included in the image data is vertical or horizontal; and an image rotation unit (5d) for rotating the image on the basis of the determination result from the grid stripe direction determination unit, in a manner such that the head direction in the region of the test subject (20) captured in the image aligns with the top direction on the display screen in the image display unit (6). Therein, the image display unit (6) displays the rotated image.

Description

X-ray diagnostic imaging apparatus and image display method

The present invention relates to an X-ray diagnostic imaging apparatus and an image display method, and particularly to a technique for displaying a captured image of a subject obtained by radiography using an X-ray flat panel detector.

Conventionally, a device that irradiates an object with radiation and detects an intensity distribution of the radiation transmitted through the object to obtain a photographed image of the object has been widely used in industrial nondestructive inspection and medical diagnosis. . As a general method for such photographing, a film / screen method for X-rays can be mentioned. In recent years, with the advancement of digital technology, a method for obtaining a high-quality captured image by converting a captured image into an electrical signal, processing the electrical signal, and reproducing the image as a visible image on a CRT or the like has been demanded. . With the progress of semiconductor process technology, an apparatus for taking a photographed image in the same manner using an X-ray flat panel detector has been developed. These systems have a very wide dynamic range compared to conventional radiation systems using photosensitive films, and have the practical advantage of being able to obtain captured images that are not affected by fluctuations in radiation exposure. Have.

Such X-ray flat panel detectors have been downsized to the size of conventional analog cassettes due to technological advances, and so-called mobile digital X-ray imaging devices called electronic cassettes have been developed.

Such an X-ray flat panel detector is generally the same size as a conventional analog cassette and has a large rectangular size in order to use an existing imaging table without updating it. In the case of the rectangular size, depending on the size of the subject, there may be a case where it is inserted vertically with respect to the imaging table or a case where it is inserted horizontally. An example in the case of performing chest front imaging is shown in FIG. 1A and 1B are explanatory views showing the relationship between the insertion direction and the head and foot direction of an X-ray flat panel detector in the background art, where FIG. 1A shows vertical insertion and FIG. 1B shows horizontal insertion. As shown in FIG. 1A, when the image is vertically inserted (meaning that the flat detector 102 is inserted vertically with respect to the head-and-foot direction 101 of the standing position imaging stand 100), the image is displayed on the image display device 103. Although displayed in the vertical direction (the head of the subject imaged in the image is up), when inserted horizontally as shown in FIG. 1B, the image is displayed in the horizontal direction (image was captured in the image). The head of the subject is displayed on the right or left).

As a method of solving this problem, the user rotates an image with a GUI (Graphical User Interface) or detects the direction of a Flat Pnel Detector (hereinafter abbreviated as “FPD”) which is a kind of X-ray flat panel detector. A sensor and a rotation mechanism were installed, and it was rotating based on the information.

However, rotating the image by the user hinders the inspection workflow. Further, if an FPD direction detection sensor or a rotation mechanism is provided, the cost is increased, the configuration is further increased, and there is a risk of giving the subject a feeling of pressure.

In order to solve this problem, Patent Document 1 proposes a technique of embedding marks in the corners of an image and inverting / rotating the image.

JP 2000-107158 A

However, in the technique described in Patent Document 1, a mark may be inserted into a region in which a subject is imaged in a captured image, and the mark may interfere with diagnosis. Furthermore, since the mark has to be inserted, the workflow is hindered.

An object of the present invention is to solve the above-described problems and provide a technique capable of accurately displaying the head and foot direction on the image display device regardless of the insertion direction of the X-ray flat panel detector.

In order to achieve the above object, the present invention determines whether the fringe direction caused by the grid included in the image data is vertical or horizontal, and based on the determination result, the region of the subject imaged in the image (hereinafter referred to as “ The image is rotated so that the head direction in the “subject image” matches the upward direction on the display screen of the image display unit, and the rotated image is displayed.

According to the present invention, it is possible to provide a technique capable of accurately displaying the head and foot direction on the display unit regardless of the insertion direction of the X-ray flat panel detector.

It is explanatory drawing which shows the relationship between the insertion direction and head-and-foot direction of the X-ray flat panel detector in background art, (a) shows vertical insertion, (b) shows horizontal insertion. Schematic diagram showing a schematic configuration of the X-ray diagnostic imaging apparatus 10 according to the present embodiment. The flowchart which shows the flow of the image display process of the X-ray image diagnostic apparatus which concerns on 1st embodiment. Flow chart showing the flow of grid stripe direction discrimination processing It is explanatory drawing which shows the content of the grid stripe direction discrimination | determination process, Comprising: (a) shows the scanning direction of a line, (b) shows the frequency response response in case a grid stripe direction is vertical, (c) is a line direction. (D) shows the frequency response response when the grid stripe direction is horizontal, and (e) shows the relationship between the line direction and the grid stripe direction is horizontal. Show. Flow chart showing the flow of head and foot rotation processing Explanatory drawing which shows the content of the head-and-foot rotation process in the table photographing stand for the lying position The flowchart which shows the flow of a process of 2nd embodiment. Explanatory drawing which shows the process of 2nd embodiment. The flowchart which shows the flow of processing of a third embodiment. Explanatory drawing which shows the process of 3rd embodiment.

The X-ray diagnostic imaging apparatus according to the present embodiment is disposed so as to face an X-ray tube that irradiates a subject with X-rays, a grid that removes scattered radiation components generated by the subject, and the X-ray tube. An X-ray flat panel detector that detects transmitted X-rays of the subject and outputs image data, an image display unit that displays an image based on the image data, and a fringe direction caused by the grid included in the image data The head direction in the region (subject image) of the subject photographed in the image is determined based on the determination result by the grid stripe direction determination unit and the grid stripe direction determination unit. An image rotation unit that rotates the image so as to coincide with the upward direction on the display screen of the image display unit. The image display unit displays the rotated image.

Further, the grid stripe direction determination unit performs a fast Fourier transform process on the image data, the value of the grid stripe frequency response, or the ratio between the grid stripe frequency response and the frequency response in the vicinity of the grid stripe frequency, May be used to determine the grid stripe direction.

In addition, the grid stripe direction determination unit may perform the fast Fourier transform process on a direct X-ray region in which X-rays are directly incident on the image.

Further, the grid stripe direction determining unit determines the grid stripe frequency according to an imaging distance between the subject and the X-ray tube when the image data is acquired by the X-ray image diagnostic apparatus. May be.

The image rotation unit further includes a detector insertion direction storage unit that stores insertion direction information indicating an insertion direction of the X-ray flat panel detector with respect to an imaging table that stores the grid and the X-ray flat panel detector. The rotation direction of the image is determined based on the determination result by the grid stripe direction determination unit and the insertion direction information so that the head direction of the subject in the image matches the upward direction in the image display unit. The image may be rotated.

Also, the insertion direction information is a parameter that associates the head-and-foot direction of the imaging table with the insertion direction of the X-ray plane device with respect to the imaging table, and rotates the image 180 degrees and rotates 90 degrees to the right. Alternatively, the information may be associated with either left 90 ° rotation.

The image rotation unit extracts a subject region where the subject is imaged in the image, detects a head-foot direction of the subject, and based on the detection result, the rotation direction of the image is rotated to the right or It may be determined whether the rotation is counterclockwise.

Further, a storage unit that stores the rotation information determined by the image rotation unit along with the image data may be further provided.

In addition, the image display method according to the present embodiment is obtained by imaging the subject using an X-ray diagnostic imaging apparatus including a grid that removes scattered radiation components generated by the subject and an X-ray flat panel detector. A step of reading the obtained image data, a step of determining whether the stripe direction caused by the grid included in the image data is vertical or horizontal, and an image based on the image data based on the determination result A step of rotating the image so that a head direction in the region of the subject (subject image) coincides with an upward direction on a display screen on which the image is displayed; and the rotated image is displayed on the display screen. And a step of displaying.

Hereinafter, embodiments of the present invention will be described more specifically with reference to the drawings. The same reference numerals are given to the procedures having the same functions and the same processing contents, and the description thereof will not be repeated.

FIG. 2 is a schematic diagram showing a schematic configuration of the X-ray image diagnostic apparatus 10 according to the present embodiment. The X-ray diagnostic imaging apparatus 10 is disposed so as to face the X-ray tube 1 that irradiates the subject 20 with X-rays, the grid 2 that removes scattered radiation components generated by the subject 20, and the X-ray tube 1. An X-ray plane detector 3 for detecting transmitted X-rays of the specimen 20, an imaging table 4 in which the grid 2 and the X-ray plane detector 3 are stored, and storage of image data output from the X-ray plane detector 3 And an image processing device 5 that performs image processing, and an image display device 6 that displays image data stored in the image processing device 5.

The image processing device 5 includes an image storage unit 5a for storing image data, image data output from the X-ray flat panel detector 3, or a scattered light removal grid (hereinafter referred to as a captured image read by the image processing device 5). A grid stripe direction discriminating section 5b for discriminating whether the stripe direction of 2 is vertical or horizontal, and a detector insertion direction in which insertion direction information of the X-ray flat panel detector 3 in the imaging table 4 is stored. A storage unit 5c, and an image rotation unit 5d that rotates an image stored in the image storage unit 5a based on information from the insertion direction information and the grid stripe direction determination unit 5b.

The image storage unit 5a and the detector insertion direction storage unit 5c are configured to include a nonvolatile or volatile storage device, for example, a memory, a magnetic disk, or a nonvolatile memory included in the hardware configuring the image processing device 5. The Further, the grid stripe direction discriminating unit 5b and the image rotating unit 5d perform fast Fourier transform (FFT Fourier Transform; hereinafter abbreviated as “FFT”) on the read image data, and give a response response of the grid stripe frequency. A program for causing a computer to execute an image display method including a step of calculating and determining a grid stripe direction based on the calculated result, a step of performing image rotation processing using the determination result, and hardware for executing the program And are configured by cooperation.

In the present embodiment, the grid stripe direction of the image data output from the X-ray flat panel detector 3 provided in the X-ray image diagnostic apparatus 10 is determined and the image is rotated. The image processing apparatus 5 may read the image data of the photographed image and perform image processing similar to the above on the image data.

An outline of image display processing of the X-ray image diagnostic apparatus according to the first embodiment will be described with reference to FIG. FIG. 3 is a flowchart showing a flow of image display processing of the X-ray image diagnostic apparatus according to the first embodiment. Hereinafter, description will be made along the order of steps in FIG.

(Step S1)
Image data is acquired from the X-ray flat panel detector 3 and temporarily stored in the image storage unit 5a. The grid stripe direction determining unit 5b determines the grid stripe direction included in the image data. When the vertical direction is determined, the vertical direction flag is stored. When the horizontal direction is determined, the horizontal direction flag is stored (S1). Details of this step will be described later.

(Step S2)
The image rotation unit 5d reads insertion direction information indicating the insertion direction of the X-ray flat panel detector 3 with respect to the imaging table 4 from the detector insertion direction storage unit 5c. The insertion direction information determines whether to insert from the right side or the left side of the imaging table when the X-ray diagnostic imaging apparatus 1 or the imaging table 4 is installed, and is stored as a setting value when the imaging table 4 is installed. The head-and-foot direction of the imaging platform 4 is expressed as a parameter corresponding to the determined insertion direction, and the image rotation direction corresponding to the parameter is associated and stored as insertion direction information. Then, the image rotation unit 5d uses the insertion direction information read from the detector insertion direction storage unit 5c and the grid stripe direction information in step S1 to adjust the image to the head and foot direction of the image display device 6. It is determined whether or not rotation of the data in the direction of the head and feet is unnecessary (S2). If unnecessary, the process proceeds to step S4. If necessary, the process proceeds to step S3.

(Step S3)
The image rotation unit 5d performs head and foot rotation processing (S3). When the grid stripe direction is vertical, it is rotated 180 degrees, and when the grid stripe direction is horizontal, it is rotated 90 degrees. You may memorize | store the rotation flag discriminate | determined by the vertical / horizontal discrimination | determination of the said grid stripes, and the head / foot discrimination | determination process as incidental information of an image. For example, by storing the history of image rotation and information indicating the rotation direction, such as “IMEGEROTATION: 1”, as supplementary information of DICOM (note: a kind of medical image communication protocol), You can see in which direction it was taken later. Details of this step will be described later. Saving as DICOM incidental information is only one example of saving, and may be saved as image incidental information of another project, or image rotation history and rotation direction are associated with information for identifying an image. May be saved.

(Step S4)
The image processing device 5 executes processing necessary before image display processing, such as grid stripe removal processing, and displays an image after rotation processing or an image that does not require rotation on the image display device 6 (S4). At this time, the up-and-down direction of the image display device 6 and the head-and-foot direction of the subject image included in the displayed captured image match.

If necessary, the image data in the image storage unit 5a is updated to the image data after the rotation process, and the process ends.

<Grid stripe direction discrimination processing>
The grid stripe direction determination process will be described with reference to FIGS. FIG. 4 is a flowchart showing a flow of grid stripe direction discrimination processing. 5A and 5B are explanatory diagrams showing the contents of the grid stripe direction discrimination process, where FIG. 5A shows the scanning direction of the line, FIG. 5B shows the frequency response response when the grid stripe direction is vertical, and (c ) Shows the relationship between the line direction and the grid stripe direction being vertical, (d) shows the frequency response response when the grid stripe direction is horizontal, and (e) is the case where the line direction and grid stripe direction are horizontal. Shows the relationship. Hereinafter, description will be made along the order of steps in FIG.

(Step S11)
The grid stripe direction determination unit 5b scans an arbitrary line in the image 50 (S11). Line scanning is preferably performed in the vicinity of the center of the image 50 in order to avoid a position in the image 50 where grid stripes are difficult to detect, such as an aperture region. In line scanning, all line processing may be performed, but processing may be performed for each predetermined number of lines in order to shorten processing time. Furthermore, in order to remove noise components, smoothing processing or the like may be performed after the FFT processing.

In this embodiment, line scanning is advanced at 100 line intervals. Furthermore, an upper limit value (for example, n times) of the number of line scans is set. If the number of line scans is less than or equal to the upper limit (corresponding to “No”), the process proceeds to step S12. If line scanning has been performed for the upper limit number of times, it is determined that line scanning has ended (corresponding to “Yes”), and the process proceeds to step S16.

In the present embodiment, as shown in FIG. 5A, first, the line 50t that is 100 lines above the center line 50m of the image 50 is read, and in the next loop, the line that is 100 lines below the center line 50m. The line scan is advanced to 50u.

(Step S12)
The grid stripe direction discriminating unit 5b performs an FFT process on one line read in step S11 (S12).

(Step S13)
The grid stripe direction determination unit 5b determines the presence or absence of grid stripes based on the response Rg of the grid stripe frequency (S13). The grid stripe direction determination unit 5b determines that there is a grid when the ratio between the response Rg of the grid stripe frequency and the response Ra of the neighboring frequency is equal to or greater than the threshold th. As shown in FIG. 5C, when grid stripes exist in the direction orthogonal to the line, when the FFT processing is performed, the horizontal axis indicates the frequency and the vertical axis indicates the response, as shown in FIG. 5B. In the response distribution diagram 51, there is a peak in the grid fringe frequency band Rg. In addition, in the image 52 in which the response distribution corresponds to the luminance, the luminance is rendered higher (white) in the grid fringe frequency band than in the surrounding area. In the present embodiment, the threshold value th is 2.0.

When the X-ray flat panel detector is inserted in the horizontal direction (see (e) of FIG. 5), as shown in the distribution diagram 53 of (d) of FIG. .

If it is determined that there are grid stripes, the process proceeds to step S14. If it is determined that there is no grid stripes, the process proceeds to step S15, the line scanning position is changed, and the process returns to step S11.

Alternatively, the grid stripe direction determination unit 5b may be configured to determine that there is a grid stripe when the response Rg of the grid stripe frequency is equal to or greater than a predetermined value.

(Step S15)
The grid stripe direction discriminating unit 5b adds a vertical direction flag and ends the grid stripe direction discrimination process (S15).

(Step S16)
If grid stripes are not detected even after the processes from step S11 to step S14 are repeated a predetermined number of times, the grid stripe direction discriminating unit 5b attaches a horizontal direction flag and ends the grid stripe direction discrimination processing (S16).

<Head and foot rotation processing>
The head and foot rotation process will be described with reference to FIGS. FIG. 6 is a flowchart showing the flow of the head and foot rotation process. FIG. 7 is an explanatory diagram showing the contents of the head-and-foot rotation process in the table for taking a standing position.

7 is assumed that the head direction 71h and the foot direction 71l are determined in advance in the position table photographing base 70 (hereinafter, abbreviated as "photographing base 70"). It is also assumed that the image reading start position 3a and the image reading direction 3b of the X-ray flat panel detector 3 are known. Further, in the captured image obtained from the X-ray flat panel detector 3, the upper left corner of the display screen in the image display device 6 corresponds to the image reading start position 3a, and the direction from the left to the right of the display screen and the image reading direction 3b. It is known that the captured image is displayed so that the direction along the line matches.

Further, regarding the relationship between the imaging table 70 and the insertion direction of the X-ray flat panel detector 3, it is inserted such that the long side of the rectangular X-ray flat panel detector 3 coincides with the long side of the imaging table 70. There are “insertion” and “horizontal insertion” in which the long side of the rectangular X-ray flat panel detector 3 is aligned with the short side of the imaging table 70. With respect to the case, the case of inserting from the right side of the top surface of the imaging table 70 and the case of inserting from the left side can be considered. Therefore, in the following, four types of insertion direction information of “vertical insertion and right insertion”, “vertical insertion and left insertion”, “lateral insertion and right insertion”, and “lateral insertion and left insertion” will be described.

(For vertical insertion and right insertion)
In this case, the parameter indicating the relationship between the head and foot directions 71h and 71l of the imaging table 70 and the insertion direction (vertical insertion and right insertion) of the X-ray flat panel detector 3 is set to “0”. With the parameter “0”, as described above, the upper left corner of the display screen in the image display device 6 corresponds to the image reading start position 3a, and the captured image read from the X-ray flat panel detector 3 corresponds to the image reading start position 3a. When the display direction and the direction along the image reading direction 3b coincide with each other, the head direction of the captured image coincides with the upward direction on the display screen of the X image display device 6 (“state 0 before image rotation”). Equivalent to '"). Therefore, since the image rotation process is unnecessary, insertion direction information “0: output as it is” indicating that the image rotation is unnecessary is stored for the parameter 0.

(For vertical insertion and left insertion)
In this case, the parameter indicating the relationship between the head and foot directions 71h and 71l of the imaging table 70 and the insertion direction (vertical insertion and left insertion) of the X-ray flat panel detector 3 is set to “1”. In the parameter “1”, the image reading start position 3 a of the X-ray flat panel detector 3 is located on the foot side of the imaging table 70. Therefore, the foot side of the subject 20 is imaged on the image reading start position 3 a side of the X-ray flat panel detector 3. In this state, when a captured image is displayed on the image display device 6 with the image reading start position 3a of the X-ray flat panel detector 3 as the upper left corner, the subject's foot is up (the “state before image rotation” in the displayed captured image). In other words, the head-and-foot direction of the photographed image is inverted 180 degrees and displayed. Therefore, when the captured image read from the X-ray flat panel detector 3 is rotated 180 degrees and then displayed on the image display device 6, the captured image is displayed on the image display device 6 with the head side up. Therefore, for the parameter “1”, the insertion direction information “1: 180 ° rotation” indicating that the image needs to be rotated 180 ° is stored.

(In case of horizontal insertion and right insertion)
In this case, the parameter indicating the relationship between the head and foot directions 71h and 71l of the imaging table 70 and the insertion direction (lateral insertion and right insertion) of the X-ray flat panel detector 3 is set to “2”. In the parameter “2”, the image reading start position 3 a of the X-ray flat panel detector 3 is located on the foot side of the imaging table 70. Further, the image reading direction 3b coincides with the head direction 71h of the imaging table 70. Therefore, the foot side of the subject 20 is photographed on the image readout start position 3a side of the X-ray flat panel detector 3, and the head direction of the subject 20 is photographed along the image readout direction 3b. In this state, when a captured image is displayed on the image display device 6 with the image reading start position 3a of the X-ray flat panel detector 3 as the upper left corner, the foot side of the subject 20 is left and the head side is right in the displayed captured image. (Corresponding to “state 2 ′” before image rotation), that is, the head direction of the captured image is displayed by being rotated 90 degrees to the right with respect to the upper direction of the display screen. Therefore, when the captured image read from the X-ray flat panel detector 3 is rotated 90 degrees to the left and then displayed on the image display device 6, the captured image is displayed on the image display device 6 with the head direction facing upward. Therefore, for the parameter “2”, the insertion direction information “2: 90 ° left rotation” indicating that the image needs to be rotated 90 ° to the left is stored.

(In case of horizontal insertion and left insertion)
In this case, the parameter indicating the relationship between the head and foot directions 71h and 71l of the imaging base 70 and the insertion direction (lateral insertion and left insertion) of the X-ray flat panel detector 3 is set to “3”. In the parameter “3”, the image reading start position 3 a of the X-ray flat panel detector 3 is located on the head side of the imaging table 70. Further, the image reading direction 3b coincides with the foot direction 71l of the imaging table 70. Therefore, the head side of the subject is photographed on the image readout start position 3a side of the X-ray flat panel detector 3, and the foot direction 71l of the subject 20 is photographed along the image readout direction 3b. In this state, when a captured image is displayed on the image display device 6 with the image reading start position 3a of the X-ray flat panel detector 3 as the upper left corner, the head side of the subject 20 is left and the foot side is right in the displayed captured image. (Corresponding to “state 3 ′” before image rotation), that is, the head direction of the captured image is rotated 90 degrees to the left with respect to the upper direction of the display screen. Therefore, when the captured image read from the X-ray flat panel detector 3 is rotated 90 degrees to the right and then displayed on the image display device 6, the captured image is displayed on the image display device 6 with the head direction upward. Therefore, the insertion direction information “3: 90 ° right rotation” indicating that the image needs to be rotated 90 ° to the right is stored for the parameter “3”.

In the present embodiment, the above four cases have been described. Usually, the user decides either right insertion or left insertion when installing the imaging stand 70. Then, two patterns of insertion direction information corresponding to the determined insertion direction and the insertion direction (vertical insertion, horizontal insertion) of the X-ray flat panel detector 3 are stored in advance in the detector insertion direction information storage unit 5c as set values. Keep it. Then, when the image rotation unit 5d performs the head-foot rotation process, the image rotation unit 5d determines which of the two patterns of insertion direction information corresponds from the detector insertion direction storage unit 5c, and performs the head-foot rotation process.

Hereinafter, the head-and-foot rotation process in the table for taking a stand position will be described in the order of steps in FIG.

(Step S21)
The image rotation unit 5d reads the vertical and horizontal flags stored in the grid stripe direction discrimination process. If the value is vertical, the process proceeds to step S22. If the value is horizontal, the process proceeds to step S24 (S21).

(Step S22)
The image rotation unit 5d refers to the insertion direction information stored in the detector insertion direction storage unit 5c, and proceeds to the 0 or 1 branch. In the case of 0, it is output as it is. If 1, the process proceeds to step S23 (S22).

(Step S23)
The image rotation unit 5d rotates the image by 180 degrees and outputs it (S23).

(Step S24)
In the case of the horizontal flag, the image rotation unit 5d refers to the insertion direction information in the horizontal direction stored in the detector insertion direction storage unit 5c, and proceeds to

branch

2 or 3. If it is 2, the process proceeds to step S25, and if it is 3, the process proceeds to step S26 (S24).

(Step S25)
The image rotation unit 5d rotates the image 90 degrees to the left and outputs it, and ends the head-foot rotation process (S25).

(Step S26)
The image rotation unit 5d rotates the image 90 degrees to the right and outputs it, and ends the head and foot rotation process (S26).

According to this embodiment, the head and foot direction can be accurately displayed on the image display device regardless of the insertion direction of the X-ray flat panel detector.

<Second embodiment>
Next, 2nd embodiment is described based on FIG. 8, FIG. The second embodiment is an embodiment that contributes to improving the accuracy of grid stripe direction detection processing. Here, FIG. 8 is a flowchart showing a processing flow of the second embodiment. FIG. 9 is an explanatory diagram showing processing of the second embodiment. Hereinafter, description will be made along the order of steps in FIG.

(Step S201)
The grid stripe direction determination unit 5b extracts a region that is not a subject region (subject image) from the captured image. The region that is not the subject region (subject image) referred to here is not a diaphragm region or subject region that reduces X-ray exposure as shown in FIG. 9, but a region directly irradiated with X-rays (hereinafter referred to as “directly”). X-ray region ”). As shown in FIG. 9, the grid stripe direction determination unit 5b directly extracts an X-ray region 91 from the captured image 90 (S201).

(Steps S202 to S204)
The grid stripe direction determination unit 5 b sets an arbitrary line in the extracted direct X-ray region 91. Subsequently, based on the line, the grid stripe direction determination process described in step S1 is executed.

Hereinafter, as in the first embodiment, the grid direction is determined for the extracted direct X-ray region (S202). If the vertical direction is determined, the vertical direction flag is stored and the process proceeds to the next step. If it is discriminated as the horizontal direction, the horizontal direction flag is stored. Next, using the insertion direction information in the detector insertion direction storage unit 5c, the image rotation unit 5d determines whether or not the rotation in the head and foot direction is necessary (S203). If unnecessary, go to the next step. If necessary, it is rotated 180 degrees or right or left 90 degrees (S204). In the case of 180 degree rotation, it is implemented when the grid direction is vertical. The 90 degree rotation is performed when the grid direction is horizontal.

According to the present embodiment, since the grid stripe direction is determined using only the direct X-ray region in which the subject is not imaged, noise such as signal components of the subject does not enter, so that the detection accuracy is improved. .

<Third embodiment>
Next, a third embodiment will be described based on FIGS. 10 and 11. The third embodiment is an embodiment that contributes to the accuracy of the head and foot rotation process. Here, FIG. 10 is a flowchart showing a processing flow of the third embodiment. FIG. 11 is an explanatory diagram showing processing of the third embodiment. Hereinafter, description will be made along the order of the steps in FIG.

(Step S301)
The grid stripe direction is determined with respect to the captured image 110 (S301). The grid stripe direction discrimination process may be either the process of the first embodiment or the second embodiment. If the vertical direction is determined, the vertical direction flag is stored and the process proceeds to the next step. If the horizontal direction is determined, the horizontal direction flag is stored and the process proceeds to the next step.

(Step S302)
The image rotation unit 5d extracts a subject region (subject image) 111 from which the subject is photographed from the photographed image 110, and determines the head and foot direction based on the feature amount of the subject region (S302). . As shown in FIG. 11, the image rotation unit 5d acquires information on the cervical vertebrae, the clavicle, and the shoulder joint in the head direction when photographing the chest front. In addition, information on the heart and the diaphragm can be acquired as the foot direction. Furthermore, the head and foot direction can be estimated from the shape of the lung field. Thus, by extracting the positions of human organs and bones, it is possible to determine the head and foot direction.

As an example of the determination process of the head and foot direction of the image rotation unit 5d, for example, one direction of the captured image 110 is scanned to generate a density profile. Then, the spread of the density profile is sequentially compared along a direction orthogonal to the one direction. In the case of a chest image, line scanning is performed along the arrow AA 'in FIG. 11, and a density profile is generated for each line. Then, the widths of the density profiles are compared. Since the width of the density profile of the neck is narrower than the width of the density profile of the chest, by comparing these, the position of the neck with respect to the chest can be known, and the head and foot direction can be determined. Alternatively, when line scanning is performed along the arrow BB ′ in FIG. 11 and a density profile is generated for each line, there is no subject region (subject image) closer to the head than the shoulder portion. The shape becomes a shape biased to one side (chest). Therefore, the position of the neck relative to the chest can be known from the shape of the density profile, and the head and foot direction can be determined.

The image rotation unit 5d determines the head and foot direction from the density profile generated based on the subject region (subject image), and determines whether or not the head and foot rotation is necessary. If unnecessary, go to the next step. If necessary, the process proceeds to step S303.

(Step S303)
If the grid stripe direction is the vertical direction, the image rotation unit 5d rotates the captured image by 180 degrees. If it is in the horizontal direction, it rotates 90 degrees to the right or left.

According to the present embodiment, since the head and foot direction can be determined regardless of the insertion direction information, an image whose insertion direction information is unknown, for example, a photographed image whose insertion direction is unknown because it has been captured by another X-ray diagnostic imaging apparatus is read. Thus, when displaying on the image display device, the head direction of the captured image can be displayed in the upward direction of the image display device.

<Other embodiments>
In addition to the above embodiment, when using a thinned image, the grid fringe frequency differs depending on the imaged subject-X-ray tube distance, so a table in which the grid fringe frequency is determined in advance for each thinning number and photographing distance is prepared. The grid fringe direction discriminating unit 5b reads the thinning number and the subject-X-ray tube distance included in the imaging conditions and display conditions, and refers to the above table to determine the grid fringe frequency suitable for each condition. It may be set.

Furthermore, although the grid fringe frequency band changes according to the grid density and the pixel size of the X-ray flat panel detector, the grid fringe frequency discriminating unit 5b may detect and use the corresponding grid fringe frequency for the processing.

In the above embodiment, an example of a rectangular X-ray flat panel detector has been described. However, even in the case of a square X-ray flat panel detector, the present invention is applied based on an image reading position and a reading direction. be able to.

1: X-ray tube, 2: Scattered ray removal grid, 3: X-ray flat detector, 4: Imaging table, 5: Image processing device, 6: Image display device, 10: X-ray image diagnostic device, 20: Covered Specimen

Claims

An X-ray tube that irradiates the subject with X-rays;
A grid for removing scattered radiation components generated by the subject;
An X-ray flat panel detector disposed opposite to the X-ray tube, detecting transmitted X-rays of the subject and outputting image data;
An image display unit for displaying an image based on the image data;
A grid stripe direction determination unit for determining whether the stripe direction caused by the grid included in the image data is vertical or horizontal;
Based on the determination result by the grid stripe direction determination unit, the image is rotated so that the head direction in the region of the subject imaged in the image matches the upward direction on the display screen of the image display unit. An image rotation unit,
The image display unit displays the rotated image;
An X-ray diagnostic imaging apparatus characterized by the above.
The grid fringe direction determination unit performs a fast Fourier transform process on the image data, and uses a value of a grid fringe frequency response or a ratio between the grid fringe frequency response and a frequency response in the vicinity of the grid fringe frequency. To determine the grid stripe direction,
The X-ray image diagnostic apparatus according to claim 1.
The grid stripe direction determination unit performs the fast Fourier transform process on a direct X-ray region in which X-rays are directly incident on the image.
The X-ray image diagnostic apparatus according to claim 2.
The grid fringe direction determination unit determines the grid fringe frequency according to an imaging distance between the subject and the X-ray tube when the image data is acquired by the X-ray image diagnostic apparatus.
The X-ray image diagnostic apparatus according to any one of claims 1 to 3, wherein
A detector insertion direction storage unit for storing insertion direction information indicating an insertion direction of the X-ray flat panel detector with respect to an imaging table for storing the grid and the X-ray flat panel detector;
The image rotation unit determines a rotation direction of the image based on a determination result by the grid stripe direction determination unit and the insertion direction information, and a head direction of the subject in the image is an upward direction in the image display unit. Rotate the image to match
The X-ray image diagnostic apparatus according to claim 1.
The insertion direction information is a parameter that associates the head-and-foot direction of the imaging table and the insertion direction of the X-ray plane with respect to the imaging table, and rotates the image 180 degrees, rotates 90 degrees to the right, or It is information that associates any of the left 90 degrees rotation,
The X-ray image diagnostic apparatus according to claim 5.
The image rotation unit extracts a subject region where the subject is imaged in the image, detects a head-foot direction of the subject, and based on the detection result, the rotation direction of the image is rotated to the right or To determine if it is counterclockwise,
The X-ray image diagnostic apparatus according to claim 1.
A storage unit for storing the rotation information determined by the image rotation unit attached to the image data;
The X-ray image diagnostic apparatus according to claim 1.
A step of reading image data obtained by imaging the subject by an X-ray image diagnostic apparatus comprising a grid for removing scattered radiation components generated by the subject and an X-ray flat panel detector;
Determining whether the fringe direction caused by the grid included in the image data is vertical or horizontal;
Based on the determination result, the step of rotating the image so that the head direction in the region of the subject imaged in the image based on the image data matches the upward direction on the display screen on which the image is displayed. When,
Displaying the rotated image on the display screen;
An image display method comprising: