JP2011067509A - Radiographic system and photographing control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate a difference between a photographing range set to a subject and an actual photographing range. <P>SOLUTION: A specialist moves an FPD 12 vertically by an operating part 27 to adjust the position of a first mark 12a of the FPD 12 to the upper end of the desired photographing range W of the subject to set an upper end position Y<SB>T</SB>, and to adjust the position of a second mark 12b of the FPD 12 to the lower end of the photographing range W to set a lower end position Y<SB>B</SB>. A moving range computing part 19a determines a range from coordinates "Y<SB>T</SB>+Δ" to coordinates "Y<SB>B</SB>-Δ" as a moving range for moving the FPD 12 in long-sized photographing using a correction amount Δ computed by a mathematical expression (1): Δ=L×(¾Y<SB>T</SB>-Y<SB>B</SB>¾/2)/(SID-L) based on the set upper and lower end positions Y<SB>T</SB>, Y<SB>B</SB>, a distance SID from the FPD 12 to an X-ray source 11 and a distance L from the FPD 12 to the subject M. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a radiography system for generating an image by detecting radiation such as X-rays emitted from a radiation source and transmitted through a subject with a radiation detector, and an imaging control method thereof. The present invention relates to a radiation imaging apparatus that enables long imaging as described above and an imaging control method thereof.

  2. Description of the Related Art Conventionally, in the medical field, long imaging has been performed in which imaging is performed on the entire spine and all lower limbs, mainly for the purpose of measuring bones of a patient (subject). When a flat panel detector (FPD) that directly captures a radiographic image as a digital image is used as a radiation detector in this long imaging, there is a limitation on the size of the detection area, and imaging of the entire spine and all lower limbs is performed. Since the region cannot be imaged by one imaging operation, the FPD is linearly moved in the body axis direction of the subject, and the imaging operation is performed a plurality of times, and the images obtained by each imaging operation are synthesized. A long image is being created.

  In long imaging using this FPD, it is necessary to move the radiation source so that radiation emitted from the radiation source at each imaging position of the FPD accurately enters the detection area of the FPD. This radiation source movement method includes a “linear movement method” in which the radiation source is linearly moved in accordance with the movement of the FPD, and an angle of the radiation source so that the radiation irradiation direction is changed in accordance with the movement of the FPD. The “swing method” to be changed is known.

  The radiation emitted from the radiation source is not a parallel beam but a diffuse beam. Thereby, in the above linear movement method, the incident angle to the FPD of the radiation that passes through a predetermined position on the subject changes due to the change in the positional relationship between the radiation source and the subject. There is a problem in that “image shift” occurs in the direction, and it is impossible to accurately connect images when creating a long image. However, in one of the swinging methods, since the positional relationship between the radiation source and the subject is fixed, it is known that the above problems are alleviated and suitable for long imaging (see, for example, Patent Document 1). ).

  In long imaging, the imaging range varies depending on the physical characteristics of the subject (height, crotch length, etc.), so an engineer needs to set the imaging range according to the subject. As an imaging range setting method, a movement start position and an end position on the FPD side are set, and the radiation source follows this, and a movement start position and an end position on the radiation source side are set, and the FPD is added to this. (See, for example, Patent Document 2). Comparing the former and the latter, the imaging range can be set on the FPD side located near the subject, so that the technician can perform the setting work while supporting the subject (patient). It has the following advantages.

  Further, in the long imaging, since the FPD is moved as described above and the imaging cannot be performed by bringing the subject into contact with the FPD, it is necessary to arrange the subject apart from the FPD to some extent. For example, in the case of standing imaging in which imaging is performed with the subject standing upright, a partition for supporting the subject is arranged in the vicinity of the standing stand that holds the FPD movably (for example, patents) Reference 3).

JP 7-59764 A JP 2004-358254 A JP 2008-142265 A

  However, in the conventional radiation imaging system in which the radiation source is swung in the long imaging, as shown in FIG. 9, the movement start position P1 and end of the FPD 100 are simply matched with the height of the imaging range W1 of the desired subject. When the position Pn is set, the subject M is separated from the FPD 100, so that a range actually captured on the subject M (a range through which radiation is transmitted) W2 becomes narrower than the set imaging range W1. There is.

  The present invention has been made in view of the above problems, and provides a radiation imaging system and a control method thereof that can eliminate the difference between the imaging range set for the subject and the actual imaging range. For the purpose.

  In order to achieve the above object, a radiation imaging system of the present invention obtains image data by detecting a radiation source that irradiates a subject with radiation, and a radiation image that is positioned opposite to the radiation source and transmitted through the subject. A radiation detector, detector moving means for linearly moving the radiation detector, and an angle for changing the radiation irradiation angle with the position of the radiation source fixed so as to follow the movement of the radiation detector A change means, an operation setting means for enabling setting of an imaging range of the subject by moving the radiation detector to position two points having different movement directions of the radiation detector, and the operation The coordinates of the two points set by the setting means, the first distance from the radiation detector to the radiation source with respect to the direction orthogonal to the moving direction of the radiation detector, and the radiation detection A moving range determining means for determining a moving range at the time of imaging of the radiation detector so that the entire imaging range of the subject is imaged based on a second distance from the tester to the subject; An imaging position determining means for determining a plurality of imaging positions in the range; and the radiation detector is moved to each imaging position determined by the imaging position determining means, and the radiation irradiation by the radiation source and the radiation detector Imaging control means for executing radiation detection.

  In addition, it is preferable to provide image collection processing means for creating long image data by collecting and synthesizing image data obtained by the radiation detector at each imaging position.

  A radiation source moving unit configured to move the radiation source in a moving direction of the radiation detector; and the imaging control unit controls the radiation source moving unit to set the radiation source at a center position of the imaging range. It is preferable to do.

Further, the moving range determining means uses the correction amount Δ calculated by the following formula (1) when the coordinates of the two points are Y _T and Y _B (where Y _T > Y _B ), A range from the coordinate “Y _T + Δ” to the coordinate “Y _B −Δ” is preferably set as the movement range.
Δ = L × (| Y _T −Y _B | / 2) / (SID−L) (1)
(Here, SID is the first distance and L is the second distance.)

Also, the moving range determination means, the coordinates on the movement direction of the radiation detector of the radiation source and _{Y F,} the coordinates of the two points and _{Y T} and _{Y B} (where _{Y T> Y F> Y B} ) when using the correction amount delta _T and delta _B is calculated by the following equation (2) and equation (3), the range of the coordinate _{"Y T} + _{Δ T"} to coordinate _{"Y B -Δ B"} The moving range is used.
_{Δ T = L × (| Y} T -Y F |) / (SID-L) ··· Equation (2)
_{Δ B = L × (| Y} F -Y B |) / (SID-L) ··· Equation (3)
(Here, SID is the first distance and L is the second distance.)

  Moreover, it is preferable to provide a supporting means for supporting the subject.

  Further, based on detection values of the radiation detector, the radiation source, and a position detection means for detecting a position of the support means in a direction orthogonal to a moving direction of the radiation detector, based on the detection value of the position detection means, It is preferable to provide a distance calculation means for calculating the first distance and the second distance.

  Moreover, it is preferable that the radiation source includes a diaphragm device that regulates radiation so that a radiation irradiation region coincides with a detection region of the radiation detector.

  The radiation detector preferably includes a sighting device that emits a visible light beam in a direction perpendicular to the moving direction from one end and the other end of the detection region in the moving direction.

  Further, the imaging position determining means, when the overlapping amount of the detection region of the radiation detector at the adjacent imaging position is larger than a predetermined upper limit value, the overlapping amount as the upper limit value, It is preferable to determine a position where each photographing position is shifted as the photographing position.

  In addition, the radiation detector includes a plurality of detection elements that convert X-rays directly or indirectly into charges and store them, a plurality of thin film transistors that read charges from each detection element, and the read charges that are converted into voltage signals. A flat panel detector provided with an integrating amplifier is preferable.

  Furthermore, an imaging control method of the radiation imaging system of the present invention includes a radiation source that irradiates a subject with radiation, and a radiation detection that obtains image data by detecting a radiation image that is positioned opposite to the radiation source and transmitted through the subject. A detector, a detector moving means for linearly moving the radiation detector, and an angle changing means for changing the irradiation angle of the radiation while fixing the position of the radiation source so as to follow the movement of the radiation detector. And an operation setting means that enables the setting of the imaging range of the subject by moving the radiation detector and positioning two points with different movement directions of the radiation detector. In the imaging control method of the imaging system, whether the radiation detector is related to the coordinates of the two points set by the operation setting means and the direction orthogonal to the moving direction of the radiation detector. Based on the first distance to the radiation source and the second distance from the radiation detector to the subject, the entire radiation imaging range of the subject is imaged. Determining a moving range; determining a plurality of imaging positions in the moving range; moving the radiation detector to each imaging position; irradiating radiation by the radiation source; and radiation by the radiation detector. And performing detection.

  According to the present invention, the coordinates of the set imaging range, the first distance from the radiation detector to the radiation source in the direction orthogonal to the moving direction of the radiation detector, and the second distance from the radiation detector to the subject. Based on the above, the range of movement of the radiation detector during long imaging is determined so that the entire imaging range of the subject is captured, so the imaging range set for the subject and the actual imaging range are Differences can be eliminated.

1 is a schematic diagram illustrating a configuration of an X-ray imaging system according to a first embodiment of the present invention. (A) is a figure which shows each imaging position at the time of long imaging | photography, (B) is a figure which shows the image data acquired at each imaging position. It is a flowchart explaining the effect | action of an X-ray imaging system. (A) is a figure which shows each imaging position when n = 3 and overlap amount (gamma) is large (about 30% of FOV), (B) is a figure which shows the image data acquired at each imaging position. It is. It is a figure explaining the X-ray imaging system which concerns on 2nd Embodiment of this invention, (A) is a figure which shows each imaging position when n = 3 and the duplication amount (gamma) is restrict _| limited to the upper limit value (gamma) _u . FIG. 6B is a diagram illustrating image data acquired at each photographing position. It is a figure explaining the X-ray imaging system which concerns on 3rd Embodiment of this invention. It is a figure explaining the X-ray imaging system which concerns on 4th Embodiment of this invention. It is a figure explaining the X-ray imaging system which concerns on 5th Embodiment of this invention. It is a figure explaining a prior art.

(First embodiment)
In FIG. 1, an imaging system of an X-ray imaging system 10 according to the first embodiment of the present invention detects an X-ray source 11 that irradiates a subject M with X-rays, and X-rays that have passed through the subject M. A flat panel detector (FPD) 12 that generates image data, a telescopic arm 13 that is suspended from the ceiling and holds the X-ray source 11 so as to be movable in the vertical direction (Y direction), and installed on the floor. Is provided so as to be movable in the vertical direction, and a partition 15 disposed close to the standing stand 14 so as to support the subject M.

  The control processing system of the X-ray imaging system 10 includes a keyboard and the like, and includes an input unit 16 for inputting imaging conditions and an imaging start instruction, a CPU, and an operation program. Main control unit 17 that controls the entire system in response to a command input, imaging control unit 18 that controls operations of X-ray source 11 and FPD 12 for performing long imaging, and movement range of FPD 12 during long imaging Or, a shooting condition determination unit 19 that determines a shooting position within the moving range, and image data shot by the FPD 12 at each shooting position of the long shooting is collected and combined to obtain long image data. The image collection processing unit 20 for creating the image, the image memory 21 for storing the long image data, the image based on the long image data, the operation menu necessary for shooting, etc. And a display control unit 23 to be displayed on the shown monitor 22.

  The X-ray source 11 includes an X-ray tube 24 that generates X-rays with a high voltage from a high-voltage generator (not shown), and a subject M out of X-rays emitted from the X-ray tube 24. It comprises a collimator (X-ray diaphragm) device 25 that limits the irradiation field to a rectangular shape so as to shield a portion that does not contribute to the X-ray image. The collimator device 25 has a movable collimator leaf (shielding blade), and changes the opening of the collimator leaf based on the control of the imaging control unit 18.

  Since the X-rays are emitted radially from the focal point 24a of the X-ray tube 24, the X-rays emitted through the collimator device 25 spread in a quadrangular pyramid shape. The angle range of the X-rays emitted from the collimator device 25 (hereinafter referred to as collimator angle) is adjusted by driving the collimator leaf so that the X-ray irradiation range substantially matches the detection area (effective field of view) of the FPD 12. Is done. “Θ” in the figure indicates a collimator angle in the Y direction.

  Further, the X-ray source 11 is provided with a swing mechanism 26 that angularly displaces the X-ray source 11 about the focal point 24a of the X-ray tube 24 so as to change the X-ray irradiation direction in the vertical direction. . At the time of long photographing, the swinging operation (angular displacement) of the X-ray source 11 is performed by the swing mechanism 26 so as to follow the vertical movement of the FPD 12.

  In the FPD 12, a plurality of X-ray detection elements are arranged on a matrix substrate on which thin film transistors (TFTs) are two-dimensionally arranged so as to correspond to each TFT. The electric charge corresponding to is generated and accumulated. This accumulated charge is read when the TFT is turned on. As the X-ray detection element, a direct conversion type and an indirect conversion type are known, and any type of X-ray detection element can be used.

The direct conversion type X-ray detection element includes a conversion layer such as amorphous selenium (a-Se) that directly converts X-rays into electric charges, and a capacitor that accumulates electric charges converted by the conversion layers. One indirect conversion type X-ray detection element uses a scintillator such as gadolinium oxide (Gd ₂ O ₃ ) or cesium iodide (CsI) that converts X-rays into visible light, and the visible light converted by the scintillator into charges. It consists of a photodiode that converts and accumulates. The FPD 12 has, for example, a rectangular detection area of 43 cm × 43 cm.

  The FPD 12 is a scanning control circuit that scans TFTs row by row and sequentially turns on the TFTs in each row, and an integration amplifier that integrates charges output from the X-ray detection elements through the TFTs and converts them into voltage signals. An A / D converter that digitizes the voltage signal converted by the integrating amplifier and generates image data is provided.

The standing stand 14 includes a moving mechanism that linearly moves the FPD 12 up and down while keeping the detection area of the FPD 12 in the horizontal direction (X direction). The standing stand 14 is provided with an operation unit 27 for setting an imaging range W of the subject M. The imaging range W shown in the figure is an example of the imaging range when performing whole spine imaging. Operation unit 27 includes a move button for moving the FPD12 vertically, photographic range W first setting button for setting the upper end position Y _T, the imaging range W second for setting the lower end position Y _B of And a setting button.

In the FPD 12, a first mark 12a indicating the upper end position of the detection area and a second mark 12b indicating the lower end position of the detection area are formed on the side surface of the casing by printing or the like. When the engineer sets the shooting range W, the FPD 12 is moved upward by operating the movement button of the operation unit 27, and the first setting button is pressed at a desired position, whereby the first mark 12a of the FPD 12 is set. the corresponding position is set as the upper end position Y _T of the imaging range W. In addition, the position corresponding to the second mark 12b of the FPD 12 is moved to the lower end position of the shooting range W by moving the FPD 12 downward by operating the movement button of the operation unit 27 and pressing the second setting button at a desired position. It is set as the Y _B.

An operation signal from the operation unit 27 is transmitted to the main control unit 17. The movement of the FPD 12 is comprehensively controlled by the main control unit 17, and the main control unit 17 recognizes the position of the FPD 12 in the Y direction and the length of the detection area and performs control, so the FPD 12 The upper end position Y _T and the lower end position Y _B can be specified based on the position information and the type of the operation signal from the operation unit 27. The main control unit 17, when the first and second setting button of the operation unit 27 is pressed, to identify each upper end position Y _T and the lower end position Y _B, and inputs the imaging condition decision unit 19.

  In order to specify the position of the FPD 12 more accurately, a position detection sensor such as a potentiometer may be provided in the moving mechanism of the FPD 12 in the standing stand 14. Moreover, it is preferable to arrange the operation unit 27 at a place where an engineer can easily operate, and the operation unit 27 is not limited to the standing stand 14 and may be arranged on the FPD 12.

The main control unit 17 is input to the imaging control unit 18 calculates the center position Y _C of the upper end position Y _T and the lower end position Y _B. Photographing control section 18 controls the expansion ratio of the telescopic arm 13, such that the focal point 24a of the X-ray tube 24 to the height of the center position Y _C is positioned to move the X-ray source 11.

The input unit 16 includes a distance L in the X direction from the position X ₀ of the detection surface of the FPD ₁₂ to the center position X ₁ of the subject M (hereinafter referred to as an FPD inter-subject distance L), and a position X ₀ of the detection surface of the FPD 12. from the distance to the position _{X 2} of the focal point 24a of the X-ray tube 24 SID (hereinafter, FPD as focal distance SID) and it is enabled input. The position of the subject M can be easily measured, for example, by marking the normal standing position of the subject M on the partition 15. The FPD inter-focal distance SID and the FPD inter-subject distance L are input by an engineer from the input unit 16, and the input values are input to the imaging condition determination unit 19 via the main control unit 17.

  The photographing condition determining unit 19 calculates a moving range calculating unit 19a that calculates a moving range of the FPD 12 during long shooting, a collimator angle calculating unit 19b that calculates a collimator angle, and a shooting position of the FPD 12 within the moving range. And an imaging position calculation unit 19c.

The movement range calculation unit 19a is based on the upper and lower end positions Y _T and Y _{B of} the imaging range W, the FPD inter-subject distance L, and the FPD inter-focal distance SID input from the main control unit 17. An X-ray irradiation angle range φ for irradiating W is obtained, and an upper end position Y _T ′ and a lower end position Y _B ′ of the movement range of the FPD 12 corresponding to the irradiation angle range φ are calculated. This irradiation angle range φ is obtained by the following equation (1).

φ = 2 × tan ⁻¹ {(| Y _T −Y _B | / 2) / (SID−L)} Expression (1)

The upper end position Y _T of the movement range _'is a position shifted upward by the correction amount Δ to the upper end position Y _T of the imaging range W. Similarly, the lower end position Y _B of the movement range _'is a correction amount Δ shifted by a position downward of the lower end position Y _B of the photographic range W. This correction amount Δ is obtained by the following equation (2) based on the geometric relationship.

Δ = L × tan (φ / 2)
= L × (| Y _T −Y _B | / 2) / (SID−L) (2)

At the time of long photographing, the FPD 12 uses the position where the height of the first mark 12a coincides with the upper end position Y _T ′ (= Y _T + Δ) as the movement start position, and the height of the second mark 12b as the lower end position Y _B ′. A position that coincides with (= Y _B −Δ) is set as a movement end position, and the position is moved between the movement start position and the movement end position. Needless to say, the movement start position may be the movement end position, and the movement end position may be the movement start position.

  The collimator angle calculation unit 19b calculates the collimator angle based on the FPD inter-focal distance SID and the length of the detection region (effective visual field) of the FPD 12. When the length in the Y direction of the detection region of the FPD 12 is FOV, the collimator angle θ with respect to the Y direction is obtained by the following equation (3). The collimator angle in the X direction is calculated similarly.

θ = 2 × tan ⁻¹ {(FOV / 2) / SID} Expression (3)

A collimator angle θ which is obtained by the formula (3), the center of the detection region of the FPD device 12 is, when in the center position _{Y C} of the movement range of the FPD device 12, at an angle irradiation area of X-rays is equal to the detection region of the FPD device 12 is there. At the time of long photographing, the opening degree of the collimator leaf of the collimator device 25 is set so that the collimator angle θ is set to the value obtained by the above equation (3). Incidentally, according to the center of FPD12 is displaced upward or downward from the center position Y _C, for optimum collimator angle irradiation area of X-rays is equal to the detection region of FPD12 decreases, correcting the angular change As described above, the collimator angle may be changed according to the position of the FPD 12.

The imaging position calculation unit 19c determines the imaging position of the FPD 12 based on the distance between the upper end position Y _T ′ and the lower end position Y _B ′ and the length FOV in the Y direction of the detection area of the FPD 12. Specifically, _{first, {(| Y T '-Y} B' | -1) / FOV + 1} is calculated, and calculates the number of photographing times n by rounding up the following calculation result decimal point. When the number of times of photographing n is determined, as shown in FIG. 2A, the movement start position P1 where the height of the first mark 12a coincides with the upper end position Y _T ′, and the height of the second mark 12b is the lower end position Y. A movement end position Pn that coincides with _B ′ is determined, and a position that equally divides between the movement start position P1 and the movement end position Pn by the number of (n−1) is set as another photographing position.

For _{example, | Y T '-Y B'} | = 100cm, if the FOV = 43cm _{is, {(| Y T '-Y} B' | -1) / FOV + 1} for ≒ 2.3, shooting count n Is calculated as “3”, and the interval between the photographing positions P1, P2, and P3 is 28.5 cm.

  FIG. 2B shows image data I1, I2,..., In obtained by the FPD 12 at the respective photographing positions P1, P2,. In the adjacent image data, an overlap region 30 is generated due to the overlap of the detection regions of the FPD 12 at the adjacent photographing positions. The overlap amount γ of the overlap region 30 is a value calculated by the following equation (4).

_{γ = (n × FOV- | Y} T '-Y B' |) / (n-1) ··· (4)

  The image collection processing unit 20 collects image data I1, I2,..., In obtained by the FPD 12 at each photographing position P1, P2,. Generate. About the overlap area | region 30, the joint between images is made not conspicuous by performing an averaging process. The long image data generated by the image collection processing unit 20 is stored in the image memory 21.

  Next, the operation of the X-ray imaging system 10 configured as described above will be described with reference to the flowchart shown in FIG. First, as an imaging preparation, an engineer arranges the standing stand 14 and the partition 15 at appropriate positions with respect to the X-ray source 11, measures the FPD inter-focal distance SID and the FPD inter-subject distance L, These values are input using the input unit 16 (step S1).

Next, the engineer operates the movement button of the operation unit 27 in a state where the subject M is upright along the partition 15, and the first mark 12 a of the FPD 12 is placed at the upper end of the imaging range W of the desired subject. set the upper end position Y _T by pressing the first setting button by aligning, pressing the second setting button align the second mark 12b of FPD12 the lower end of the imaging range W of the subject to be desired setting the lower end position _{Y B} by (step S2). Of course, sometimes the upper end position Y _T and the lower end position Y _B is set in the reverse order.

When the setting operation in step S2 is completed, the input value and the set value are input to the imaging condition determination unit 19, and the movement range calculation unit 19a moves the upper end position Y _T ′ (= Y _T + Δ) and the lower end position Y _B ′ (= Y _B −Δ) are calculated, the collimator angle calculation unit 19b calculates the collimator angle θ, and the shooting position calculation unit 19c calculates the shooting positions P1, P2,. .. Pn is calculated (step S3).

Then, as the photographing control section 18 controls the expansion ratio of the telescopic arm 13, the focus 24a of the X-ray tube 24 to the height of the center position Y _C of the upper end position Y _T and the lower end position Y _B is located, The X-ray source 11 is moved (step S4). Further, the imaging control unit 18 controls the collimator device 25 to adjust the opening of the collimator leaf so that the angle range in the X-ray height direction is the collimator angle θ calculated in step S3. (Step S5).

  Further, the imaging control unit 18 controls the movement of the FPD 12 and the angle of the X-ray source 11 to set the FPD 12 to the imaging position P1 (initial position), and the X-ray irradiation range substantially matches the detection area of the FPD 12. Thus, the angle of the X-ray source 11 is set to the initial position (step S6).

  Thereafter, the X-ray imaging system 10 is in a waiting state for an imaging start instruction (step S7). When an imaging start instruction is input from the input unit 16 by the engineer (step S7: YES), the imaging control unit 18 moves the FPD 12 from the imaging position P1 to the imaging positions P2,. While changing the angle of the X-ray source 11 so that the X-ray irradiation range almost always coincides with the detection region of the FPD 12, the X-rays generated by the X-ray source 11 at the respective imaging positions P1, P2,. An irradiation operation and a detection operation by the FPD 12 are executed (step S8).

  Next, the image collection processing unit 20 collects the image data I1, I2,..., In obtained by the FPD 12 at each photographing position P1, P2,. Processing is performed to generate long image data (step S9). The long image data is stored in the image memory 21 and displayed on the image display monitor 22 by the display control unit 23 as an X-ray image.

(Second Embodiment)
In the first embodiment, the photographing position calculation unit 19c sets the position where the height of the first mark 12a of the FPD 12 coincides with the upper end position Y _T ′ as the movement start position P1, and sets the height of the second mark 12b as the lower end position. Since the position that coincides with Y _B ′ is the movement end position Pn, the ratio of the overlap amount γ of the overlap region 30 to the length FOV of the detection region of the FPD 12 may increase. FIG. 4 shows a case where n = 3 and the amount of overlap γ is large (about 30% of FOV). Thus, when the overlap amount γ is large, the exposure amount of the subject M is increased in the overlap region 30, and therefore it is preferable to provide an upper limit for the overlap amount γ. Therefore, as a second embodiment of the present invention, a shooting position determination method by the shooting position calculation unit 19c when an upper limit is provided for the overlap amount γ will be described.

  In the present embodiment, the shooting position calculation unit 19c first calculates the shooting positions P1, P2,..., Pn by the method described in the first embodiment, and uses the above equation (4) to determine the overlap amount. γ is calculated. Then, it is determined whether or not the overlapping amount γ is larger than a predetermined upper limit value (for example, a length of 10% of FOV). If the overlapping amount γ is larger than the upper limit value, the overlapping amount γ is set to the upper limit value. , Pn are shifted evenly in the vertical direction.

In FIG. 5, when n = 3 and the overlap amount γ is limited to the upper limit value γ _u , the first mark 12a of the FPD 12 at the movement start position P1 is shifted upward from the upper end position Y _T ′, and the movement end position P3 2 shows that the second mark 12b of the FPD 12 is shifted downward from the lower end position Y _B ′. The shift amount δ between the first and second marks 12a and 12b is a value calculated by the following equation (5).

δ = (γ−γ _u ) × (n−1) / 2 Expression (5)

  In the second embodiment, long photographing is performed by the same method as in the first embodiment after correcting the photographing positions P1, P2,..., Pn of the FPD 12 as described above. Since other configurations are the same as those in the first embodiment, description thereof is omitted.

(Third embodiment)
In the first embodiment, the FPD inter-focal distance SID and the FPD inter-subject distance L are measured by an engineer and input to the X-ray imaging system 10 from the input unit 16. It is also preferable that the FPD inter-focal distance SID and the FPD inter-subject distance L are automatically acquired. This specific example will be described below as a third embodiment.

  In FIG. 6, a ceiling traveling rail 40 that holds the telescopic arm 13 movably in the horizontal direction (X direction) is laid on the ceiling, and a standing stand 14 and a partition 15 are independently provided on the floor. A floor running rail 41 is laid so as to be movable in the horizontal direction. Thereby, the engineer can adjust the FPD inter-focal distance SID and the FPD inter-subject distance L by changing the horizontal positions of the telescopic arm 13, the standing stand 14, and the partition 15.

  The first to third position sensors 42 to 44 are sensors each including a potentiometer that detects the horizontal position of the telescopic arm 13, the standing stand 14, and the partition 15, and inputs the detected values to the distance calculation unit 45. . The distance calculation unit 45 calculates the FPD inter-focal distance SID and the FPD inter-subject distance L based on the detection values input from the first to third position sensors 42 to 44, and uses the calculated values as the main values described above. Input to the control unit 17. Other configurations are the same as those in the first embodiment, and are not shown in the figure.

As described above, in the X-ray imaging system of the third embodiment, since the X-ray imaging system automatically acquires the FPD inter-focal distance SID and the FPD inter-subject distance L, the movement range (upper end position Y) of the FPD 12 during long imaging. _T ′ and the lower end position Y _B ′) are set more accurately.

(Fourth embodiment)
In the first embodiment, by setting the height of the X-ray source 11 so that the height of the focal point 24a of the X-ray tube 24 is coincident with the central position Y _C of the imaging range W is carried out long shooting , when the expansion rate and the like of the telescopic arm 13 is constrained may not be able to set a focal point 24a to the center position Y _C of the imaging range W. An X-ray imaging system that enables the long imaging even in such a case will be described below as a fourth embodiment.

In the present embodiment, the main controller 17, when controlling the telescopic arm 13 through the imaging control unit 18, it is impossible to set the focus 24a to the center position Y _C of the imaging range W is shown in FIG. 7 as such, the focus 24a to closest position to the center position Y _C, to set the height of the X-ray source 11. The main control unit 17 is always aware of the height of the focus 24a, inputs the height Y _F of the focal 24a in this case the movement range calculation unit 19a.

Movement range calculation unit 19a, the correction amount delta _T of the upper end position Y _T and the lower end position Y _B for accurately photographing the photographing range _{is W,} the delta _B, is calculated using the following equation (6) and (7) .

_{Δ T = L × (| Y} T -Y F |) / (SID-L) ··· (6)
_{Δ B = L × (| Y} F -Y B |) / (SID-L) ··· (7)

In this case, the upper end position Y _T of the movement range of the FPD device 12 _'becomes the position shifted upward by the correction amount delta _T to the upper end position Y _T of the imaging range W, the lower end position Y _B of the movement _range' is photographic range W consisting of lower end position Y _B correction amount delta _B shifted by position downwards. Since other configurations are the same as those in the first embodiment, description thereof is omitted.

(Fifth embodiment)
In the first embodiment, the first and second marks 12a and 12b are added to the FPD 12 at the positions indicating the lower end position and the lower end position of the detection area so as to assist the technician in setting the imaging range W of the subject M. However, another embodiment for supporting the setting of the shooting range W will be described below.

  In this embodiment, instead of the first and second marks 12a and 12b, as shown in FIG. 8, the visible light beam VB is emitted in the horizontal direction to the FPD 12 at positions corresponding to the lower end position and the lower end position of the detection region. First and second sights 50a and 50b are provided. Since the subject M or the screen 15 is irradiated by the visible light beam VB, the technician can set the imaging range W more accurately by using the irradiation position of the visible light beam VB as a guide. Since other configurations are the same as those in the first embodiment, description thereof is omitted.

  In each of the above embodiments, the present invention has been described by taking as an example the case of standing imaging in which the FPD is moved in the vertical direction with respect to a subject in a standing posture, but the present invention is not limited thereto, and The present invention can also be applied to the supine imaging in which the FPD is moved in the horizontal direction with respect to the subject in the posture.

  In each of the above embodiments, the FPD is moved in the body axis direction (longitudinal direction) of the subject. However, the present invention is not limited to this, and the FPD is moved in a direction different from the body axis direction of the subject. May be.

  Further, in each of the above embodiments, the long image data is created by collecting and synthesizing the image data obtained by the FPD at each image capturing position. However, the long image data is not created and the FPD is used. A plurality of images based on the obtained image data may be displayed side by side on one or a plurality of display monitors.

10 X-ray imaging system 11 X-ray source (radiation source)
12 Flat panel detector (radiation detector)
12a 1st mark 12b 2nd mark 13 Telescopic arm (radiation source moving means)
14 Standing stand (detector moving means)
15 Screen (support means)
16 Input unit 17 Main control unit 18 Shooting control unit (shooting control means)
19 shooting condition determining unit 19a moving range calculating unit (moving range determining means)
19b Angle calculation unit 19c Shooting position calculation unit (shooting position determination means)
20 Image collection processing unit (image collection processing means)
24 X-ray tube 24a Focus 25 Collimator device (aperture device)
26 Swing mechanism (angle changing means)
27 Operation unit (operation setting means)
30 overlap area 42 1st position sensor (position detection means)
43 Second position sensor (position detecting means)
44 3rd position sensor (position detection means)
45 Distance calculation unit (distance calculation means)
50a First sight 50b Second sight P1 Movement start position Pn Movement end position

Claims (12)

A radiation source for irradiating the subject with radiation;
A radiation detector which is positioned opposite to the radiation source and detects a radiation image transmitted through the subject to obtain image data;
Detector moving means for linearly moving the radiation detector;
Angle changing means for changing the irradiation angle of the radiation while fixing the position of the radiation source so as to follow the movement of the radiation detector;
An operation setting means for enabling setting of an imaging range of the subject by moving the radiation detector to position two different points in the moving direction of the radiation detector;
The coordinates of the two points set by the operation setting means, a first distance from the radiation detector to the radiation source in a direction orthogonal to the moving direction of the radiation detector, and the subject from the radiation detector to the subject A moving range determining means for determining a moving range at the time of imaging of the radiation detector so that the entire imaging range of the subject is imaged based on the second distance to
Shooting position determining means for determining a plurality of shooting positions in the moving range;
Imaging control means for moving the radiation detector to each imaging position determined by the imaging position determining means, and executing radiation irradiation by the radiation source and radiation detection by the radiation detector;
A radiation imaging system comprising:   The radiation imaging system according to claim 1, further comprising image collection processing means for creating long imaging data by collecting and synthesizing image data obtained by the radiation detector at each imaging position. . Radiation source moving means for moving the radiation source in the movement direction of the radiation detector;
The radiation imaging system according to claim 1, wherein the imaging control unit controls the radiation source moving unit to set the radiation source at a center position of the imaging range. When the coordinates of the two points are Y _T and Y _B (where Y _T > Y _B ), the moving range determining means uses the correction amount Δ calculated by the following equation (1) to generate a coordinate “ The radiation imaging system according to claim 3, wherein a range from Y _T + Δ ”to coordinates“ Y _B −Δ ”is set as the movement range.
Δ = L × (| Y _T −Y _B | / 2) / (SID−L) (1)
(Here, SID is the first distance and L is the second distance.) The moving range determining means is configured such that the coordinates of the radiation source in the moving direction of the radiation detector are Y _F and the coordinates of the two points are Y _T and Y _B (where Y _T > Y _F > Y _B ). to, by using the correction amount delta _T and delta _B is calculated by the following equation (2) and equation (3), the range of the coordinate _{"Y T} + _{Δ T"} to coordinate _{"Y B -Δ B",} the The radiation imaging system according to claim 1, wherein the radiation range is a moving range.
_{Δ T = L × (| Y} T -Y F |) / (SID-L) ··· Equation (2)
_{Δ B = L × (| Y} F -Y B |) / (SID-L) ··· Equation (3)
(Here, SID is the first distance and L is the second distance.)   The radiation imaging system according to claim 1, further comprising support means for supporting the subject.   Based on the detection values of the radiation detector, the radiation source, and the support means, respectively, with respect to a direction perpendicular to the moving direction of the radiation detector, and the detection value of the position detection means, the first The radiation imaging system according to claim 6, further comprising a distance calculation unit that calculates a distance and the second distance.   The radiation imaging system according to claim 1, wherein the radiation source includes a diaphragm device that regulates radiation so that a radiation irradiation region matches a detection region of the radiation detector. .   The said radiation detector is equipped with the sighting device which inject | emits a visible light beam in the direction orthogonal to the said moving direction from the one end and other end of the detection area | region in the said moving direction, The any one of Claim 1 to 8 characterized by the above-mentioned. The radiation imaging system according to item.   The imaging position determining means is configured so that when the overlapping amount of the detection area of the radiation detector at an adjacent imaging position is larger than a predetermined upper limit value, the imaging amount determining unit sets the overlapping amount as the upper limit value. The radiation imaging system according to claim 1, wherein a position shifted is determined as the imaging position.   The radiation detector includes: a plurality of detection elements that convert X-rays directly or indirectly into charges; a plurality of thin film transistors that read charges from each detection element; and an integration that converts the read charges into voltage signals. The radiation imaging system according to any one of claims 1 to 10, wherein the radiation imaging system is a flat panel detector including an amplifier. A radiation source that irradiates the subject with radiation, a radiation detector that is positioned opposite to the radiation source and detects a radiation image that has passed through the subject and obtains image data, and detection that moves the radiation detector linearly Moving means, angle changing means for changing the irradiation angle of the radiation while fixing the position of the radiation source so as to follow the movement of the radiation detector, and moving the radiation detector to move the radiation detector. In an imaging control method of a radiation imaging system comprising: an operation setting unit that enables setting of an imaging range of the subject by setting the positions of two points having different moving directions of the device;
The coordinates of the two points set by the operation setting means, a first distance from the radiation detector to the radiation source in a direction orthogonal to the moving direction of the radiation detector, and the subject from the radiation detector to the subject Determining a moving range at the time of imaging of the radiation detector so that the entire imaging range of the subject is imaged based on the second distance to
Determining a plurality of shooting positions in the moving range;
Moving the radiation detector to each of the imaging positions, and executing radiation irradiation by the radiation source and radiation detection by the radiation detector;
An imaging control method for a radiation imaging system, comprising:

Images