JP2009291356A - X-ray imaging apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the time for radiography and to reduce the dose of radiation by optimizing the number of images to be captured for the long radiography. <P>SOLUTION: The whole areas of positions where positioning markers set on a screen are projected on an FPD are set as fixed overlapping areas in advance. A subject is movable by a lifting device. The range of radiography is determined for the long radiography of the subject when the lifting device is at a reference height position, and the range of radiography is divided into a plurality of sections to determine a plurality of irradiation fields for the radiography. Then, whether the irradiation fields should be optimized or not is determined. If optimization is necessary, the range of radiography (the irradiation fields) is adjusted, and at the same time, the position of the subject is adjusted by the lifting device, so that the number of irradiation fields (the number of images to be captured) is reduced. The irradiation fields are determined so that the set fixed overlapping areas overlap between adjacent irradiation fields, and the height of an X-ray source, the direction of X-ray irradiation, the collimator diaphragm angle and the position of the FPD are controlled so that X rays are applied to the determined irradiation fields only. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an X-ray image capturing apparatus and method, and more particularly to a technique for capturing a plurality of X-ray images and connecting these X-ray images to obtain one long captured image.

  In simple X-ray imaging, there are cases where long imaging is performed on a long area such as the entire spine or the entire foot.

  Conventional computer radiography (CR) is X-ray imaging using a storage phosphor sheet (imaging plate (IP)) instead of X-ray film. In the case of performing, photographing is performed with overlapping IPs, and a long image is obtained by combining images read from the respective IPs (Patent Document 1). At this time, a marker such as lead is placed in the IP overlapping region to enable accurate alignment.

  On the other hand, in recent X-ray imaging, DR (digital radiography) that converts X-rays into electrical signals by a new X-ray flat panel detector (FPD) with a new large area from the CR method and reads them as they are. A system has been proposed, and long photographing using this FPD has also been implemented.

As an imaging method for long imaging, an X-ray tube rotating method (Patent Document 2) for imaging a plurality of times by rotating the X-ray tube, and an X-ray tube parallel moving method for imaging a plurality of times by translating the X-ray tube There is mainly (Patent Document 3).
JP 2000-232976 A JP 2004-358254 A JP-T-2006-500126

  By the way, at the time of long photographing, partial images of the subject are obtained at a plurality of positions by moving the position of the FPD, and the whole image is obtained by connecting them, but a plurality of X-ray images are photographed. It is preferable that a screen for supporting the subject is installed at a predetermined position in front of the FPD so that the subject does not move while he / she is moving.

  In addition, when a marker for alignment is placed on a partition and the FPD is moved to take an image, the image is taken so that the marker is located in an overlapping area between X-ray images. Is preferably used for alignment.

  However, when it is considered to place a marker in the overlapping area as described above, the relationship between the FPD 1 and the marker 2 varies as shown in FIGS. 17A and 17B according to the long shooting range. . In addition, since there is a partition-FPD distance, the position where the marker 2 is reflected also changes depending on the position of the X-ray source.

  Regardless of the long imaging range or the position of the X-ray source, in order to always put the marker in the overlapping area of the FPD, it is possible to place a large number of markers in the partition and make any of the markers enter the overlapping area. In this case, there is a problem that the marker interferes with the diagnosis.

  On the other hand, there is a problem that it takes time to change the marker each time the long imaging range or the position of the X-ray source is set.

  The present invention has been made in view of such circumstances, and long imaging in which an alignment marker is always placed in an overlapping region of an X-ray flat panel detector regardless of the long imaging range or the position of the X-ray source. It is an object of the present invention to provide an X-ray imaging apparatus and method that can be easily realized and can prevent an unnecessary increase in the number of imaging images.

  In order to achieve the above object, an X-ray imaging apparatus according to claim 1 includes an X-ray tube and an X-ray movable diaphragm for adjusting an X-ray irradiation field irradiated from the X-ray tube. An X-ray generator having at least an elevating means for moving the X-ray source in the vertical direction, an X-ray flat panel detector for converting incident X-rays into an electrical signal, and the X-ray flat panel detector in the vertical direction An X-ray imaging unit having a standing stand to be moved to a screen, and a screen that is installed at a predetermined position in front of the X-ray imaging unit to support the subject so that the subject does not move. Further, according to the screen to which a marker for alignment between a plurality of X-ray images is attached, lifting means for moving the subject supported by the screen up and down, and the movable range of the X-ray source during long imaging The marker can be projected onto the X-ray flat detector Fixed overlap region setting means for setting a range as a fixed overlap region, and photographing for setting a photographing range at the time of long photographing for a subject on the lifting means when the lifting means is set at a reference height position Range setting means and irradiation for determining a plurality of irradiation field areas when the first imaging range set or the second imaging range in which the height of the first imaging range is adjusted is divided into a plurality of images. Field region determining means for determining each irradiation field region so that the determined fixed overlapping region overlaps between adjacent irradiation field regions, and for the first imaging range Determining means for determining whether or not the determined number of regions of each irradiation field region can be reduced, and reducing the number of regions of each irradiation field region determined for the first imaging range. If it is determined that it is possible, An adjustment amount calculating means for calculating an adjustment amount for reducing the adjustment amount for moving the set first photographing range in the vertical direction, and the setting based on the calculated adjustment amount. Shooting range adjustment means for adjusting the height to the second shooting range obtained by translating the first shooting range by the adjustment amount; and the elevating means based on the calculated adjustment amount at the reference height position And an elevation control means for moving to a position that is raised and lowered by the adjustment amount, and X is applied to the irradiation field region for each irradiation field region determined for the first imaging range or the second imaging range. A moving position determining means for determining a moving position of the X-ray plane detector so that a line is incident; and the X-ray plane detection at each position determined by the moving position determining means for each imaging during the long imaging To move the vessel sequentially X-rays are irradiated only to each of the irradiation field regions determined for the first imaging range or the second imaging range for each imaging during the long imaging, and the standing stand control means for controlling the standing stand. As described above, X-ray control means for controlling the X-ray generation unit according to each irradiation field region is provided.

  That is, the position at which the alignment marker provided on the screen is projected on the X-ray flat panel detector varies depending on the long imaging range and the position of the X-ray source. The entire area is set as a fixed overlap area. Further, a first imaging range at the time of long shooting is set for the subject on the lifting means when the lifting means is set at the reference height position.

  When determining a plurality of irradiation field areas when shooting by dividing the first imaging range into a plurality, each irradiation field area is determined so that the fixed overlapping areas overlap between adjacent irradiation field areas. . It is determined whether it is possible to reduce the number of regions in each determined irradiation field region, and if it is determined that the number of regions can be reduced, an adjustment amount for reducing the number of regions. , Determining an adjustment amount for translating the set first shooting range in the vertical direction, and moving the first shooting range by the adjustment amount based on the adjustment amount; And the elevation means is raised and lowered by the adjustment amount from the reference height position. That is, while maintaining the relative relationship between the position of the subject and the first imaging range, the height of both is adjusted by the adjustment amount.

  Thereafter, for each irradiation field area determined for the first imaging range, or when the number of areas of this irradiation field area can be reduced, the determination is made for the second imaging range. Further, the movement position of the X-ray flat panel detector is determined so that the X-rays irradiated to the irradiation field region are incident on each irradiation field region. The X-ray generation unit is controlled so that only the irradiation fields determined in this way are irradiated with X-rays, and the moving position of the X-ray flat panel detector is controlled, so that the long imaging range and X Regardless of the position of the radiation source, the marker can always be projected onto the overlapping region (fixed overlapping region) of the X-ray flat panel detector. Then, when connecting adjacent X-ray images, by connecting the X-ray images so that the markers appearing in the fixed overlapping region match, it is possible to obtain a long captured image connected with high accuracy.

  2. The X-ray imaging apparatus according to claim 1, wherein the fixed overlapping region includes a horizontal distance between the X-ray generation unit, the partition, and the X-ray imaging unit, and an installation position of the marker. And a minimum height from a maximum height position at which the marker is projected onto the X-ray flat panel detector, which is determined based on the minimum and maximum incident angles of X-rays that can be incident on the marker during long imaging. It is characterized by the range up to the position.

  As shown in claim 3, in the X-ray imaging apparatus according to claim 1 or 2, a plurality of the markers are installed in the partition at an interval narrower than a vertical length of the X-ray flat panel detector, The fixed overlapping area setting means sets the fixed overlapping area for each marker. Accordingly, it is possible to perform a long photographing that connects three or more images, and it is possible to take an arbitrary long region such as the entire spine or the entire foot of the subject as a photographing target.

  The X-ray imaging apparatus according to any one of claims 1 to 3, wherein the determination unit includes an upper end of each irradiation field area determined for the first imaging range. Each of the irradiation fields determined for the first imaging range when the total length of the irradiation field area and the lower irradiation field area is equal to or shorter than the vertical length of the X-ray flat panel detector. It is characterized by determining that the number of areas can be reduced. That is, when the total length of the irradiation field region at the upper end and the irradiation field region at the lower end of each irradiation field region is equal to or shorter than the length in the vertical direction of the X-ray flat panel detector, The number of shots can be reduced by one by adjusting the height position of both while maintaining the relative relationship with the first shooting range.

  The X-ray imaging apparatus according to any one of claims 1 to 4, wherein the adjustment amount calculation unit includes the irradiation field areas determined for the first imaging range. And the length obtained by subtracting the length of the upper-end irradiation field area or the lower-end irradiation field area from the vertical length of the X-ray flat panel detector. The adjustment amount is calculated within a range. In other words, the adjustment amount for reducing the number of shots by one is the length of the uppermost irradiation field area or the lowermost irradiation field area among the irradiation field areas determined for the first imaging range (at the upper end). The shorter one of the length of the irradiation field region and the lower irradiation field region) and the vertical length of the X-ray flat panel detector, the length of the upper irradiation field region or the lower irradiation field region. The adjustment amount can be determined within a range of a length obtained by subtracting the shorter one of the lengths of the upper and lower irradiation field regions.

  The X-ray imaging apparatus according to any one of claims 1 to 5, wherein the X-ray control unit performs the imaging when the irradiation field region is determined by the irradiation field region determination unit. A height position in the vertical direction of the X-ray source is set at the same height position as the center position of the first imaging range set by the range setting means or the height-adjusted second imaging range, and the X The X-ray irradiation direction from the X-ray source and the X-ray movable so that only the determined irradiation field region is irradiated based on the horizontal distance between the X-ray imaging unit and the X-ray imaging unit. It is characterized by controlling the aperture angle by the aperture.

  The X-ray imaging apparatus according to any one of claims 1 to 5, wherein when the irradiation field region is determined by the irradiation field region determination unit, the X-ray imaging apparatus according to any one of claims 1 to 5 The height position of the X-ray source in the vertical direction is adjusted to the center position of the field region, and X-rays are applied only to the irradiation field region determined based on the horizontal distance between the X-ray generation unit and the X-ray imaging unit. The aperture angle by the X-ray movable aperture is controlled so that is irradiated.

  That is, the invention according to claim 6 performs long imaging by the X-ray tube rotation method, and the invention according to claim 7 performs long imaging by the X-ray tube parallel movement method.

According to an eighth aspect of the present invention, the X-ray field irradiated from the X-ray source is adjusted, the vertical position of the X-ray flat panel detector is controlled, and the subject is imaged a plurality of times. In an X-ray image capturing method for acquiring a long image by connecting a plurality of X-ray images obtained from a detector, the subject is supported so as not to move to a predetermined position in front of the X-ray flat panel detector. And a step of installing a partition to which a marker for alignment between a plurality of X-ray images taken at the time of long photographing is attached, and the movement of the X-ray source at the time of long photographing A step of presetting a range in which the marker can be projected on the X-ray flat panel detector according to the range as a fixed overlapping region, and an elevating means for raising and lowering the subject supported by the screen are set at a reference height position. The lifting hand when you are The step of setting the first imaging range for the long test for the subject above and the first imaging range set above or the second imaging range obtained by adjusting the height of the first imaging range n (N: integer greater than or equal to 2) Steps for determining first to n-th irradiation field areas (FOV _{1 to} FOV _n ) when photographing by dividing into pieces, and the setting between adjacent irradiation field areas Determining each irradiation field area so that the fixed overlap areas determined overlap, and determining whether the number of areas of each irradiation field area determined with respect to the first imaging range can be reduced And an adjustment amount for reducing the number of regions when it is determined that the number of regions of each irradiation field region determined for the first imaging range can be reduced, An adjustment amount for translating the set first photographing range in the vertical direction is calculated. A step of adjusting the height to the second imaging range obtained by translating the set first imaging range by the adjustment amount based on the calculated adjustment amount, and the determined adjustment Moving the elevating means from the reference height position to the position raised or lowered by the adjustment amount based on the amount, and the first irradiation determined for the first photographing range or the second photographing range. A step of moving the X-ray flat panel detector to a first position so that X-rays irradiated to a field region (FOV ₁ ) are incident; and after the X-ray flat panel detector has moved to the first position A step of performing first imaging by irradiating only the first irradiation field region (FOV ₁ ) with X-rays from the X-ray source, and the determined second irradiation field region (after the first imaging) the X-ray flat panel detector as X-rays irradiated to the FOV ₂₎ is incident The irradiation and step of moving to the second position, after the X-ray flat panel detector is moved to the second position, the X-ray from the X-ray source only in the second exposure field region (FOV ₂₎ Performing the second imaging, and sequentially moving the X-ray flat panel detector from the first position to the nth position and sequentially performing the first to nth imaging. It is said.

  According to the present invention, the alignment marker always enters the overlap region of the X-ray flat panel detector regardless of the conditions during long imaging (long imaging range, X-ray source height, imaging distance). In addition, it is possible to automatically take a long image, and thereby it is possible to obtain a long image that is accurately connected using a marker imaged in an overlapping region of adjacent images.

  When the number of shots (number of shots) at the time of long shooting can be reduced by adjusting the position of the subject and the height position of the shooting range (first shooting range) at the time of long shooting Since the first imaging range is adjusted (changed to the second imaging range) and the subject is moved up and down to adjust the position of the subject to reduce the number of times of imaging, the imaging time can be shortened. In addition, unnecessary exposure can be prevented from increasing.

  Preferred embodiments of an X-ray imaging apparatus and method according to the present invention will be described below with reference to the accompanying drawings.

<Device configuration>
FIG. 1 is a schematic diagram showing an external appearance of an X-ray imaging apparatus according to the present invention, and FIG. 2 is a block diagram showing an embodiment of the X-ray imaging apparatus.

  As shown in FIGS. 1 and 2, the X-ray imaging apparatus 10 mainly includes an X-ray tube suspension 20, a standing stand 30, a partition 40, a lifting device 44, an X-ray controller 50, an operation console 60, image processing. It is comprised from the part 70 grade | etc.,.

  The X-ray tube suspension 20 supports an X-ray source 22 and moves the X-ray source 22 in the horizontal direction by the overhead traveling type horizontal drive unit 14 and moves in the vertical (vertical) direction by the vertical drive unit 16. Let Further, the X-ray source 22 can be rotationally driven by the rotational drive unit 18, and thereby the X-ray irradiation direction can be controlled.

  The X-ray source 22 includes an X-ray tube 23, an X-ray movable diaphragm (collimator) 24, an irradiation field lamp 25, and a mirror 26.

  The X-ray tube 23 emits X-rays with a high voltage applied from the high voltage generator 12. The collimator 24 has upper, lower, left and right diaphragm blades that limit X-rays, and these diaphragm blades are driven by a collimator driving unit 28 to adjust the X-ray irradiation field emitted from the X-ray tube 23.

  The irradiation field lamp 25 is turned on by a power source applied from the irradiation field lamp power source 27 and irradiates the subject with illumination light through the mirror 26 and the collimator 24. The irradiation field irradiated with X-rays can be confirmed by the illumination light irradiated on the body surface of the subject.

  The standing stand 30 supports an X-ray flat panel detector (FPD) 32 and moves the FPD 32 in the vertical (vertical) direction by the FPD vertical drive unit 34.

  The FPD 32 converts incident X-rays into electrical signals, and outputs the electrical signals to the image processing unit 70 as X-ray image signals. The image processing unit 70 performs various kinds of image processing such as offset (dark current) correction, noise removal, gradation conversion, and the like on the input image signal. Then, an X-ray image signal to be displayed on the monitor 72 is generated.

  The partition 40 is installed at a predetermined position in front of the standing stand 30 at the time of long photographing, and supports the subject so as not to move. A marker 42 such as lead is vertically spaced on the partition 40 in a vertical direction (FPD 32). Embedded in the vertical length of the irradiation field (narrower than the PANEL). The markers 42 are embedded on the left and right sides of the partition 40, respectively.

  The elevating device 44 moves the subject in the vertical direction by placing the subject, and moves the subject within the vertical length (PANEL) of the irradiation field of the FPD 32 according to a movement command from the X-ray controller 50.

  The operation console 60 includes an X-ray irradiation switch, an imaging condition input unit, a switch for switching between normal imaging / long-length imaging, and the like. An operation instruction input at the operation console 60 is applied to the X-ray controller 50.

  The X-ray controller 50 has a microprocessor configuration including a central processing unit (CPU), a storage program for storing processing programs, various parameters, and the like, and the CPU has an input signal from the operation console 60 and the processing described above. The entire system is controlled by a program.

  During normal imaging (when capturing a single X-ray image), the X-ray source 22 and the FPD 32 are automatically linked so that the height of the FPD 32 coincides with the efficiency and certainty of X-ray imaging. ing.

  In addition, during long imaging according to the present invention (when imaging a plurality of X-ray images by changing the imaging range), the position of the FPD 32 is controlled and the X-ray irradiation field area is controlled automatically. In addition, the number of times of imaging during long imaging is reduced by controlling the lifting device 44 as necessary and resetting the X-ray irradiation field area (useless exposure). Can be increased).

<Long image capturing device configuration>
3 and 4 are functional block diagrams showing functions of the X-ray controller 50 and the operation console 60 at the time of long photographing, FIG. 3 shows setting functions before photographing, and FIG. 4 shows overall processing functions. Is shown.

  In FIG. 3, the apparatus information acquisition unit 100 and the X-ray source movable range acquisition unit 110 acquire various types of information before imaging, and the fixed overlapping area determination unit 120 calculates a fixed overlapping area described later based on the acquired information. decide.

[Device Information Acquisition Unit 100]
The apparatus information acquisition unit 100 acquires information determined depending on the installation of the apparatus as shown in FIG.

  The information acquired by the apparatus information acquisition unit 100 is a partition-FPD distance (d) and a marker installation position (m) indicating the height position of the marker 42.

[X-ray source movable range acquisition means 110]
The system movable range of the X-ray source As shown in FIG. 6, the minimum distance of the X-ray source-FPD distance (SID) when the X-ray source 22 is moved in the horizontal direction is SID _min , and the maximum distance is SID _max The minimum height of the height (H) of the X-ray source when the X-ray source 22 is moved in the vertical direction is H _min and the maximum height is H _max . The system movable range of the X-ray source 22 is determined by the system specifications.

-Range in which the X-ray source can move during long imaging The range in which the X-ray source can actually move during long imaging is acquired within the system movable range.

As shown in FIG. 7, the maximum imaging range at the time of long imaging is AREA _max, and the X-ray source 22 with respect to the marker position (m) based on the maximum imaging range (AREA _max ) and the marker installation position (m). To calculate the height (L _min , L _max ) of the X-ray source 22 when the X-ray is incident at the sharpest angle. The height (L _min ) of the X-ray source 22 shown in FIG. 7A indicates the height when the X-ray incident angle is minimum with respect to the marker installation position (m). The height (L _max ) of the X-ray source 22 shown in (B) indicates the height when the X-ray incident angle is maximum with respect to the marker installation position (m). In addition, the X-ray source-FPD distance (SID) at that time is SID _L.

The X-ray source movable range acquisition unit 110 acquires the height range (L _{min to} L _max ) and SID _L of the X-ray source 22.

As a method of acquiring each of the above information (L _min , L _max , SID _L ), a method of calculating in advance and storing it as a preset value, a method of inputting each information itself with the operation console 60 or the like, A method of manually inputting an imaging range (AREA _max ) and calculating L _min and L _max is conceivable.

When the maximum imaging range (AREA _max ) is different for each X-ray source-FPD distance (SID), the sharpest angle with respect to the marker position (m) when all SIDs are considered. The height of the X-ray source when the X-ray enters is calculated.

[Fixed overlapping area determination means 120]
The range in which the marker is projected on the FPD includes the device information (d, m) acquired by the device information acquisition unit 100 and the information on the X-ray source movable range acquired by the X-ray source movable range acquisition unit 110 (L _min , L _max , SID _L ) can be calculated from the geometric relationship as shown in FIG.

That is, assuming that the upper end position of the range in which the marker is projected on the FPD is C _top and the lower end position is C _bottom , the upper end position (C _top ) and the lower end position (C _bottom ) can be expressed by the following equations, respectively. .

The range of C _{top to} C _bottom calculated by the above [Equation 1] is a range in which the marker can be projected on the FPD according to the movable range of the X-ray source 22. A range from C _{top to} C _bottom is determined as a fixed overlapping region.

The above example is a fixed overlap region (C _{top to} C _bottom ) determined for one marker position (m), but a plurality of markers 42 are embedded in the partition 40 as shown in FIG. Yes. Therefore, the movable range (Ln _{min to} Ln _max , SIDn _L ) of the X-ray source is determined at each marker position ( _mn ) of the plurality of markers, and the fixed overlapping region (Cn _{top to} Cn _bottom ) is determined.

The fixed overlapping area (Cn _{top to} Cn _bottom ) determined as described above may be stored in the storage means in the X-ray controller 50 as a preset value, or device information (d, m), and X radiation source movable range of the information _{(L min, L max, SID} L) may be calculated based on.

[Shooting condition setting means 130]
As shown in FIG. 4, the imaging condition setting means 130 sets a tube voltage, an irradiation dose, and a long imaging range AREA as imaging conditions for long imaging.

The long imaging range (AREA) is set by turning on the irradiation field lamp 25 as shown in FIG. 10 and setting the range of illumination light irradiated on the body surface of the subject as the height (L) of the X-ray source 22. , By adjusting the aperture angle (2θ) of the collimator 24. That is, the upper end position (AREA _top ) and the lower end position (AREA _bottom ) of the long photographing range (AREA) can be obtained from the above adjustment result by the following equation.

[Equation 2]
AREA _top = L + SID ・ tan (θ)
AREA _bottom = L-SID ・ tan (θ)
The method for setting the long shooting range (AREA) is not limited to the above method, and the operation console 60 is used to set the upper end position (AREA _top ) and the lower end position (AREA _bottom ) of the long shooting range (AREA). You may make it set manually.

  The long shooting range is set when the height position of the lifting device 44 shown in FIG. 1 is a reference height position (for example, the lowest position within the range in which height adjustment is possible). It is assumed that it is set for a subject on the device 44.

[Irradiation field calculation means 140]
The irradiation field area calculating unit 140 includes a fixed overlapping area (Cn _{top to} Cn _bottom ) determined by the fixed overlapping area determining unit 120 and a long imaging range (AREA _{top to} AREA _bottom ) set by the imaging condition setting unit 130. Based on the above, the number of shots (N), the irradiation field region (FOV _{1 to} FOV _n ), and the FPD position are determined.

The number of shots (N) is set as the number of fixed overlapping areas in the long shooting range (AREA _{top to} AREA _bottom ) +1. That is, as shown in FIG. 10A, when the number of fixed overlapping areas in the long shooting range (AREA) is 1, the number of shots (N) is set to 2, as shown in FIG. Thus, when the number of fixed overlapping areas in the long shooting range (AREA) is 2, the number of shots (N) is set to 3.

The irradiation field area (FOV _{1 to} FOV _n ) for each number of shots (N) set as described above is the lower end of the fixed overlapping area from the upper end position (AREA _top ) of the long imaging range as shown in FIG. position (C _bottom) to the area, fixed from the lower end position of the elongated imaging range from the upper end position (C _top) of the fixed overlapping area (aREA _bottom) to the region, the upper end position of the fixed overlapping area otherwise (C _top) It is determined as an area up to the lower end position (C _bottom ) of the overlapping area.

On the other hand, the FPD position corresponding to each irradiation field region (FOV _{1 to} FOV _n ) set as described above matches the center position of the irradiation field region and the center position of the FPD as shown in FIG. The center reference (FIG. 11A) set to, the upper end reference (FIG. 11B) set so that the upper end position of the irradiation field area matches the upper end position of the FPD, and the lower end position of the irradiation field area It is determined by any one of the lower end standards (FIG. 11C) set so that the lower end position of the FPD matches.

[Optimum irradiation field determination means 150]
The optimum irradiation field determination means 150 determines whether or not each irradiation field area calculated by the irradiation field area calculation means 140 needs to be optimized.

Now, as shown in FIG. 12 (A), five irradiation field regions are determined as each irradiation field region calculated by the irradiation field region calculating means 140, and the uppermost irradiation field region among these irradiation field regions, and The vertical length of the irradiation field area at the lower end is 1/3 of the total length PANEL of the FPD 32, respectively.
12B, when the long photographing range is shifted by 1/3 PANEL and the lifting device 44 is raised by 1/3 PANEL from the reference height position, four irradiation fields are obtained. Changing to an area, that is, the number of shots can be reduced by one.

  The optimum irradiation field determination means 150 determines that optimization is necessary when the number of shots can be reduced by one as described above, and determines that optimization is not required when the number of shots cannot be reduced. To do.

  That is, as shown in FIG. 13, when the length in the vertical direction of the upper and lower irradiation field areas of each irradiation field area is 1 PANEL or more (FIG. 13A). (In the case of 7/6 PANEL), it is determined that each irradiation field area is optimally divided (no optimization is required), while the added length is less than 1 PANEL (shown in FIG. 5B). (In the case of 2/3 PANEL), it is determined that each irradiation field area is not optimal division (optimization is required).

[Adjustment amount calculation means 160]
The adjustment amount calculation means 160 shown in FIG. 4 calculates the adjustment amount ADJ when it is determined that the irradiation field region needs to be optimized by the optimum irradiation field determination means 150.

As shown in FIG. 14, the adjustment amount ADJ has the length of the irradiation field area at the lower end (the length from the lower end of the imaging range to the lower end of the fixed overlap area) as the adjustment amount ADJ _bottom, and the FPD irradiation field as shown in FIG. When the length obtained by subtracting the length of the irradiation field region at the upper end from the vertical length PANEL of the region is defined as the adjustment amount ADJ _tpo , the length is determined within the range of the adjustment amount ADJ _bottom and the adjustment amount ADJ _tpo .

This adjustment amount ADJ is determined by a method of determining the adjustment amount ADJ to be the minimum, and after adjustment, the average of the adjustment amount ADJ _bottom and the adjustment amount ADJ _tpo is adjusted so that there is no bias in the irradiation field area at the top and bottom ends. A method of determining as ADJ is conceivable.

In this embodiment, the description has been given of the case where the lowest position of the lifting device 44 is set as the reference height position, and the adjustment is performed by raising from the reference height position. However, the highest position of the lifting device 44 is the reference height. It is also possible to adjust the position by lowering from the reference height position. In this case, the length of the irradiation field area at the upper end (the length from the upper end of the imaging range to the upper end of the fixed overlap area) is set as an adjustment amount ADJ _top, and the vertical length PANEL of the FPD irradiation field area is a length obtained by subtracting the length of the radiation area and adjustment amount ADJ _bottom, determines the amount of adjustment ADJ within with these adjustment amount ADJ _bottom and the adjusting quantity ADJ _tpo.

[Subject position adjusting means 170]
The subject position adjusting means 170 includes the lifting device 44 shown in FIG. 1, and adjusts the position of the subject by raising the lifting device 44 from the reference height position by the adjustment amount ADJ determined by the adjustment amount calculation means 160. To do.

[Irradiation field area adjusting means 180]
The irradiation field region adjusting unit 180 adjusts the height by translating the long shooting range AREA (first shooting range) set by the shooting condition setting unit 130 by the adjustment amount calculated by the adjustment amount calculation unit 160. The long shooting range AREA ′ (second shooting range) is adjusted (see FIGS. 14 and 15). The adjustment of the imaging range can be performed by adjusting the height L of the X-ray source 22 to the height L ′ moved in the vertical direction by the adjustment amount.

In addition, the irradiation field area adjusting unit 180 determines each irradiation field area (FOV ₁ ′ to FOV _n−1 ′) based on the height-adjusted long photographing range AREA ′ in the same manner as the irradiation field area calculating unit 140. calculate. That is, each irradiation field area (FOV _{1 to} FOV _n ) calculated based on the long shooting range AREA set by the shooting condition setting unit 130 is calculated based on the height-adjusted long shooting range AREA ′. The number of irradiation field areas (number of shots N) is reduced by one by adjusting to each irradiation field area (FOV ₁ ′ to FOV _n−1 ′).

[FPD position determination means 190]
The FPD position determining unit 190 corresponds to each irradiation field region (FOV _{1 to} FOV _n ) calculated by the irradiation field region calculating unit 140 when optimization of the irradiation field region is not necessary, and will be described with reference to FIG. the way to determine the position _{P n} of the FPD 32, whereas, if the optimization of the irradiation field is needed, irradiation field area each irradiation field calculated by the adjusting means _{180 (FOV 1 '~FOV n-} 1 Corresponding to '), the position P _N-1 ' of the FPD 32 is determined as described in FIG.

[X-ray control means 200]
The X-ray control means 200 calculates an X-ray irradiation direction (α) and a collimator aperture angle (θ) for each irradiation field region, and X-rays irradiated from the X-ray source 22 based on the calculation results. The X-ray irradiation direction (α) and the collimator aperture angle (θ) are controlled.

The X-ray irradiation direction (α) and collimator aperture angle (θ) are determined by the upper end position (FOV _NT ) and lower end position (FOV _NB ) of a certain irradiation field region (FOV _N ), the height (L) of the X-ray source 22, Based on the X-ray source-FPD distance (SID), it can be calculated from the geometric relationship as shown in FIGS.

<Operation during long shooting>
First, the operation console 60 is operated to set imaging conditions such as a long imaging range (AREA), an X-ray source-FPD distance (SID), and an X-ray source height (L). Note that the fixed overlapping area (C _{top to} C _bottom ) determined for the marker position (m) does not vary from one imaging to another, and therefore it is stored in the storage means in the X-ray controller 50 as a preset value. preferable.

When the above imaging conditions are set, the X-ray controller 50 divides the long imaging range (AREA) into n (n = number of fixed overlapping areas in the long imaging range + 1) as shown in FIG. and, n pieces of the irradiation field _(FOV 1 _{~FOV n),} and determines the position _{P n} of the corresponding FPD32 to each radiation area.

Subsequently, as described above, it is determined whether or not the irradiation field region (FOV _{1 to} FOV _n ) needs to be optimized. If the optimization is necessary, the optimized irradiation field region (FOV ₁ ′ to FOV _n-1 ′) and the position P _N-1 ′ of the FPD 32 corresponding to each irradiation field region are determined.

Thereafter, the FPD 32 is moved to a position corresponding to the determined first irradiation field region (FOV ₁ or FOV ₁ ′), and only the first irradiation field region is irradiated with X-rays from the X-ray source 22. The X-ray irradiation direction (α) and collimator aperture angle (θ) are controlled so as to stand by.

  Here, when the X-ray irradiation switch is turned on, the first irradiation field region is irradiated with X-rays, and the first X-ray imaging is performed.

Subsequently, when the first X-ray imaging is completed, the FPD 32 is moved to a position corresponding to the determined second irradiation field region (FOV ₂ or FOV ₂ ′), and the second irradiation field The X-ray irradiation direction (α) and the collimator aperture angle (θ) are controlled so that only the region is irradiated with X-rays from the X-ray source 22, and the second X-ray imaging is performed.

  When the X-ray imaging is sequentially completed according to the number of divisions of the long imaging range in this way, the image processing unit 70 performs a process of connecting a plurality of images acquired for each X-ray imaging to fix adjacent images. This is performed so that the marker images shown in the overlapping area match.

<Other embodiments>
In this embodiment, the X-ray tube rotation method in which the X-ray tube is rotated and images are taken a plurality of times has been described. The present invention can also be applied to a moving system.

  In this case, when the irradiation field region (FOV) is determined, the height of the X-ray source is adjusted to the center position of the irradiation field region, and the collimator aperture angle is set so that the X-rays are incident only on the irradiation field region. Control.

  The present invention is not limited to the above examples, and it goes without saying that various improvements and modifications may be made without departing from the scope of the present invention.

FIG. 1 is a schematic diagram showing an external appearance of an X-ray imaging apparatus according to the present invention. FIG. 2 is a block diagram showing an embodiment of the X-ray imaging apparatus. FIG. 3 is a functional block diagram illustrating functions of the X-ray controller and the operation console during long shooting, and is a diagram illustrating a setting function before shooting. FIG. 3 is a functional block diagram showing functions of the X-ray controller and the operation console at the time of long imaging, and is a diagram showing overall processing functions. FIG. 5 is a diagram used for explaining information determined depending on the installation of the X-ray imaging apparatus. FIG. 6 is a diagram used for explaining the system movable range of the X-ray source. FIG. 7 is a diagram used to explain the range in which the X-ray source can move during long imaging. FIG. 8 is a diagram used for explaining the fixed overlap region. FIG. 9 is a diagram used for explaining the method for setting the long photographing range. FIG. 10 is a diagram used for explaining a method of determining an irradiation field region. FIG. 11 is a diagram used for explaining a method of determining the FPD position. FIG. 12 is a diagram used for explaining the optimization of the irradiation field region. FIG. 13 is a diagram used for explaining a method for determining whether or not the irradiation field region needs to be optimized. FIG. 14 is a diagram illustrating an example of the irradiation field region before and after optimization. FIG. 14 is a diagram illustrating another example of the irradiation field region before and after optimization. FIG. 16 is a diagram used for explaining a method of calculating the X-ray irradiation direction (α) and the collimator aperture angle (θ). FIG. 17 is a diagram showing how the position at which the marker is projected varies depending on the position of the X-ray source.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... X-ray imaging device, 14 ... Horizontal drive part, 16 ... Vertical drive part, 18 ... Rotation drive part, 20 ... X-ray tube suspension machine, 22 ... X-ray source, 23 ... X-ray tube, 24 ... X-ray Movable diaphragm (collimator), 28 ... collimator driving unit, 30 ... standing stand, 32 ... X-ray flat panel detector (FPD), 34 ... FPD vertical driving unit, 40 ... partition, 42 ... marker, 44 ... lifting device, 50 DESCRIPTION OF SYMBOLS ... X-ray controller 60 ... Operation console 70 ... Image processing part 100 ... Apparatus information acquisition means 110 ... X-ray source movable range acquisition means 120 ... Fixed overlap area determination means 130 ... Imaging condition setting means 140 ... Irradiation field area calculation means 150 ... Optimal irradiation field judgment means 160 ... Adjustment amount calculation means 170 ... Subject position adjustment means 180 ... Irradiation field area adjustment means 190 ... FPD position determination means 200 ... X-ray control means

Claims (8)

An X-ray source having an X-ray tube and an X-ray movable diaphragm for adjusting an X-ray irradiation field irradiated from the X-ray tube, and an elevating means for moving at least the X-ray source in the vertical direction An X-ray imaging unit comprising: a line generation unit; an X-ray plane detector that converts incident X-rays into an electrical signal; and a standing stand that moves the X-ray plane detector in a vertical direction;
A partition which is installed at a predetermined position in front of the X-ray imaging unit and supports the subject not to move, and a marker for alignment between a plurality of X-ray images taken at the time of long imaging. Attached screen,
Elevating means for elevating the subject supported by the partition;
Fixed overlapping area setting means for setting, as a fixed overlapping area, a range in which the marker can be projected on the X-ray flat panel detector in accordance with the movable range of the X-ray source at the time of long imaging;
An imaging range setting means for setting an imaging range at the time of long imaging for a subject on the lifting means when the lifting means is set at a reference height position;
Irradiation field area determining means for determining a plurality of irradiation field areas when photographing by dividing the set first imaging range or the second imaging range obtained by adjusting the height of the first imaging range into a plurality of parts. An irradiation field region determining means for determining each irradiation field region so that the determined fixed overlapping region overlaps between adjacent irradiation field regions;
Determination means for determining whether or not the number of areas of each irradiation field area determined for the first imaging range can be reduced;
When it is determined that the number of areas of each irradiation field area determined for the first imaging range can be reduced, an adjustment amount for reducing the number of areas, the set first An adjustment amount calculating means for calculating an adjustment amount for translating the photographing range of 1 in the vertical direction;
Shooting range adjusting means for adjusting the height to the second shooting range obtained by translating the set first shooting range by the adjustment amount based on the calculated adjustment amount;
Elevation control means for moving the elevating means from the reference height position to a position raised or lowered by the adjustment amount based on the calculated adjustment amount;
The movement position of the X-ray flat panel detector is determined so that X-rays irradiated to the irradiation field region are incident on each irradiation field region determined for the first imaging range or the second imaging range. Moving position determining means to perform,
A standing stand control means for controlling the standing stand so as to sequentially move the X-ray flat panel detector to each position determined by the moving position determination means for each photographing at the time of the long photographing;
The X in accordance with each irradiation field region so that X-rays are irradiated only to each irradiation field region determined for the first imaging range or the second imaging range for each imaging during the long imaging. X-ray control means for controlling the line generator;
An X-ray imaging apparatus comprising:   The fixed overlapping area includes the horizontal distance between the X-ray generation unit, the partition and the X-ray imaging unit, the installation position of the marker, and the minimum and maximum incidence of X-rays that can enter the marker during long imaging. The X-ray image according to claim 1, wherein the marker is a range from a maximum height position to a minimum height position projected on the X-ray flat panel detector, which is determined based on an angle. Shooting device. A plurality of the markers are installed on the screen at an interval narrower than the vertical length of the X-ray flat panel detector,
The X-ray imaging apparatus according to claim 1, wherein the fixed overlapping area setting unit sets the fixed overlapping area for each marker.   The determination means has a length obtained by adding the upper irradiation field area and the lower irradiation field area among the irradiation field areas determined for the first imaging range. 4. The method according to claim 1, wherein it is determined that the number of irradiation field regions determined for the first imaging range can be reduced when the length is equal to or less than a length in a vertical direction. An X-ray imaging apparatus according to claim 1.   The adjustment amount calculating means includes a length of an uppermost irradiation field area or a lowermost irradiation field area of each irradiation field area determined for the first imaging range, and a vertical direction of the X-ray flat panel detector. 5. The adjustment amount is calculated within a range of a length obtained by subtracting a length of the irradiation field region at the upper end or the irradiation field region at the lower end from the length. X-ray imaging device.   When the irradiation field region is determined by the irradiation field region determination unit, the X-ray control unit determines the center of the first imaging range or the height-adjusted second imaging range set by the imaging range setting unit. A height position in the vertical direction of the X-ray source is set at the same height position as the position, and the irradiation field area determined based on a horizontal distance between the X-ray generation unit and the X-ray imaging unit 6. The X-ray according to claim 1, wherein the X-ray irradiation direction from the X-ray source and the aperture angle by the X-ray movable diaphragm are controlled so that only the X-ray is irradiated. Image shooting device.   When the irradiation field region is determined by the irradiation field region determination unit, the X-ray control unit adjusts the vertical height position of the X-ray source to the center position of the irradiation field region and the X-ray The aperture angle of the X-ray movable aperture is controlled so that only the determined irradiation field region is irradiated based on a horizontal distance between the generation unit and the X-ray imaging unit. To X-ray imaging apparatus according to any one of 5 to 5. The X-ray field irradiated from the X-ray source is adjusted, the vertical position of the X-ray flat panel detector is controlled, the subject is imaged multiple times, and a plurality of sheets obtained from the X-ray flat panel detector are obtained. In an X-ray image capturing method for acquiring a long image by connecting X-ray images,
A screen for supporting a subject to prevent movement at a predetermined position in front of the X-ray flat panel detector, and a marker for alignment between a plurality of X-ray images taken during long imaging is attached. Installing the screened screen,
Preliminarily setting a range in which the marker can be projected on the X-ray flat panel detector as a fixed overlapping region in accordance with a movable range of the X-ray source at the time of long imaging;
A step of setting a first imaging range at the time of long photographing with respect to the subject on the lifting means when the lifting means for lifting the subject supported by the screen is set at the reference height position;
The first to n-th shots when shooting by dividing the set first shooting range or the second shooting range obtained by adjusting the height of the first shooting range into n (n: integer of 2 or more). Determining the irradiation field regions (FOV _{1 to} FOV _n ), and determining each irradiation field region so that the set fixed overlapping regions overlap between adjacent irradiation field regions;
Determining whether it is possible to reduce the number of areas of each irradiation field area determined for the first imaging range;
When it is determined that the number of regions of each irradiation field region determined for the first imaging range can be reduced, an adjustment amount for reducing the number of regions, the set first Calculating an adjustment amount for translating the imaging range of 1 in the vertical direction;
Adjusting the height to the second shooting range obtained by translating the set first shooting range by the adjustment amount based on the calculated adjustment amount;
Moving the elevating means based on the determined adjustment amount from the reference height position to a position raised or lowered by the adjustment amount;
The X-ray flat panel detector is moved to the first position so that X-rays irradiated to the _first irradiation field area (FOV ₁ ) determined with respect to the first imaging range or the second imaging range are incident. A process of moving to
Irradiating only the first irradiation field region (FOV ₁ ) with X-rays from the X-ray source after the X-ray flat panel detector is moved to the first position;
Moving the X-ray flat panel detector to a second position so that X-rays irradiated to the _second irradiation field region (FOV ₂ ) determined after the first imaging are incident;
After the X-ray flat panel detector moves to the second position, irradiating only the second irradiation field region (FOV ₂ ) with X-rays from the X-ray source to perform second imaging;
An X-ray imaging method, wherein the X-ray flat panel detector is sequentially moved from the first position to the n-th position, and the first to n-th imaging is sequentially performed.

Images