JP2011078612A - Radiographing apparatus and radiographing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently perform radiographing at a large enlargement ratio extending in a wide range without forcing a subject to take an unnatural posture and without allowing unnecessary exposure to radiation, and to achieve a radiation image without a cut line. <P>SOLUTION: In this radiographing apparatus, a distance R1 between a radiation tube and an object bed, a distance R2 between the object bed and a radiation detector, and a subject size A1 in the moving direction of a detector holding table are obtained, and an enlargement ratio M is calculated based on the distances R1, R2. A total moving count n of the detector holding table, travels S1, S2 of the detector holding table at each movement, irradiation angle of radiation from a radiation source and a diaphragm of a radiation field of radiation at each movement are calculated based on the size B of the radiation detector in the moving direction of the detector holding table, the object size A1, and an enlargement ratio M. At each movement, the position of the detector holding table, the irradiation angle and the diaphragm are adjusted to detect image data from the radiation detector according to the transmitted radioactive rays of radiation applied from the radiation source. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a radiographic image capturing apparatus and a radiographic image capturing method.

  In recent years, in radiographic imaging when grasping the entire long subject such as a lower limb, an arm, and a spine, long imaging is performed. In this long shooting, the long shooting range is divided into a plurality of parts, an overlapping area for image connection is provided between the divided adjacent shooting ranges, and the overlapping area for image connection is used after the shooting of each shooting range is completed. To obtain a long image.

  For example, in a radiography apparatus including a detection panel in which radiation detection elements called flat panel detectors (FPDs) are two-dimensionally arranged, the distance in the longitudinal direction of the region of interest in the subject and the effective field of view in the FPD The movement amount of the FPD is calculated from the distance in the longitudinal direction, the FPD is moved to each photographing position based on the calculated movement amount, the diaphragm at each photographing position is adjusted, and each image data obtained at each photographing position Has been disclosed (see Patent Document 1).

  In a transmission imaging apparatus in which a sample table to which a sample is attached is movably provided in a three-dimensional direction (XYZ direction) between a radiation source and a radiation detector, a plurality of sample tables are moved in the X and Y directions sequentially. The unit images are captured, coordinate images are used to connect the unit images to obtain a composite image, the composite image and the capture selection frame are displayed, and relative coordinates are compared by comparing the selected capture selection frame with the coordinate data. Is disclosed, and a sample table is moved based on the relative coordinates to enlarge and display an image in the imaging selection frame (see Patent Document 2).

JP 2007-260027 A JP-T-2005-008228

  Phase contrast imaging is a method for capturing a highly sharp radiation image that can identify minute symptoms of a disease. In this phase contrast imaging, a subject is placed between the radiation source and the FPD, and the distance between the radiation source and the subject and the distance between the subject and the FPD are changed, so that a highly sharp phase contrast image is obtained. It is obtained.

  When Patent Document 1 is applied to this phase contrast photographing, the final movement calculation distance of the FPD must take into consideration the enlargement magnification, and an unphotographed region is generated between the photographing positions or at the same position. On the other hand, there is a risk of performing multiple exposures more than necessary.

  In addition, Patent Document 2 is an industrial transmission imaging apparatus that evaluates the bonding state of an electronic circuit board, the coating of semiconductors, electronic components, wires, chips, mold resin, etc. There is no mechanism to prevent this. Therefore, when a human body is photographed for a long time using Patent Document 2, there is a problem that unnecessary exposure may be caused to the subject and the technician who performs the photographing.

  In view of the above problems, an object of the present invention is to enable radiographic imaging with a large enlargement ratio to be efficiently performed over a wide range without forcing an unreasonable posture or unnecessary exposure to a subject, and to provide continuous radiation. It is to obtain an image.

  The invention according to claim 1 has a radiation source for irradiating radiation and a diaphragm means for adjusting an irradiation field of radiation irradiated from the radiation source, and irradiates the subject with the radiation adjusted by the diaphragm means Radiation irradiation means, adjustment of the irradiation angle of radiation from the radiation source by rotating the radiation irradiation means around an axis extending in the horizontal direction, and the amount of irradiation field irradiation by the diaphragm means Irradiating drive means for making adjustments, movable detector holding means for holding a radiation detector for detecting image data from transmitted radiation of the subject, and holding table movement for moving the first detector holding means in a substantially horizontal direction Means, a subject table provided between the radiation irradiating unit and the radiation detector, and a size of the subject in the moving direction of the detector holding unit. Based on the object size acquisition means, distance acquisition means for acquiring the distance between the radiation source and the object table, and the distance between the object table and the radiation detector, and the distance acquired by the distance acquisition means Calculating the magnification of the image data of the subject acquired by the radiation detector, and based on the size of the radiation detector in the moving direction of the detector holding means, the size of the subject, and the magnification The number of movements of the detector holding means and the amount of movement of the detector holding means for each movement are calculated, and the irradiation angle of the radiation from the radiation source for each movement and the radiation by the diaphragm means for each movement The aperture amount of the irradiation field is calculated, and the position of the detector holding unit by the holding table moving unit, the irradiation angle and the aperture amount by the irradiation driving unit are adjusted for each movement. Is allowed, a radiographic imaging apparatus, characterized in that it comprises a control means for detecting image data corresponding to the transmitted radiation of the radiation irradiated from the radiation detector from the radiation source.

  According to a second aspect of the present invention, in the radiographic imaging device according to the first aspect of the present invention, the radiographic imaging device includes a movement direction acquisition unit that acquires a movement direction of the detector holding unit, and the control unit includes the movement direction acquisition unit. The detector holding means is moved by the holding table moving means every time the movement is performed in the acquired moving direction.

  According to a third aspect of the present invention, in the radiographic image capturing apparatus according to the first or second aspect, the control means is for joining the image data in the moving direction of the detector holding means based on the magnification. Calculate the overlap width, based on the calculated overlap width for joining the image data, the size of the radiation detector in the moving direction of the detector holding means, the size of the subject, and the magnification The number of movements of the detector holding means and the amount of movement of the detector holding means for each movement are calculated.

  According to a fourth aspect of the present invention, in the radiographic image capturing apparatus according to any one of the first to third aspects, a first adjustment unit that adjusts a distance between the radiation source and the subject table, and the subject table And a second adjustment means for adjusting a distance between the radiation detector and the radiation detector.

  According to a fifth aspect of the present invention, in the radiographic imaging apparatus according to any one of the first to fourth aspects, the radiation detector is configured to output image data from a phase contrast radiation image enhanced by an edge effect of the subject. Is detected.

  According to a sixth aspect of the present invention, a distance between a radiation source that emits radiation and a subject table that holds a subject, and a distance between the subject table and a radiation detector that detects image data from transmitted radiation of the subject. Based on the distance acquisition step to acquire, the subject size acquisition step to acquire the size of the subject in the moving direction of the movable detector holding means that holds the radiation detector, and the distance acquired by the distance acquisition step An enlargement factor calculating step for calculating an enlargement factor of the image data of the subject acquired by the radiation detector, the size of the radiation detector in the moving direction of the detector holding means, the size of the subject, and the enlargement A movement amount calculating step for calculating the number of movements of the detector holding means and the movement amount of the detector holding means for each movement time based on the rate, and the movement times An irradiation drive amount calculation step of calculating an irradiation angle of radiation from the radiation source and an aperture amount of the radiation field for each movement, a position of the detector holding means for each movement, and the irradiation A radiographic imaging method comprising: a drive control step of adjusting an angle and the aperture amount and detecting from the radiation detector image data corresponding to the transmitted radiation of the radiation emitted from the radiation source. It is.

  According to the present invention, the position of the detector holding table that holds the radiation detector is moved for each movement calculated based on the size of the radiation detector, the size of the subject, and the enlargement ratio, and irradiation driving is performed. The image data can be detected by adjusting the irradiation angle and the aperture amount by the means. Therefore, it is possible to efficiently perform radiography with a large enlargement ratio over a wide range without forcing the subject to unreasonable posture or unnecessary exposure, and to obtain a continuous radiographic image. .

It is a front view of the structural example of a radiographic imaging apparatus. It is a side view of the structural example of a radiographic imaging apparatus. It is a figure which shows the structural example of a radiation detector. It is the block diagram which showed the control structure of the radiographic imaging apparatus. (A) is a figure which shows the example of contact | adherence imaging | photography, (B) is a figure which shows the example of phase contrast imaging | photography. It is a figure explaining the principle of phase contrast imaging, (A) is a figure explaining radiation refracted by the edge part of a photographic subject, and (B) is a figure explaining radiation intensity strongly detected by a photographic subject edge part. It is a flowchart of operation | movement of long imaging | photography. It is a flowchart of the operation | movement of long imaging | photography (continuation of FIG. 7). It is a figure which shows the example of calculation of the total frequency | count of a movement according to an expansion rate, and a movement amount. FIG. 3 is a relationship diagram between the radiation tube 10 and the aperture section 11. It is a conceptual diagram of adjustment of an irradiation angle and a diaphragm amount. It is a figure which shows the example of the movement amount in each imaging | photography position, an irradiation angle, and aperture_diaphragm | restriction amount. It is a figure which shows the example of the relationship between the radiation detector and radiation irradiator in each imaging position, (A) is an example in case the radiation detector is arrange | positioned in the initial position, (B) is the 1st imaging | photography. Example when the radiation detector moves to the position (imaging start position), (C) shows an example when the radiation detector moves to the second imaging position (after the first movement), and (D) shows the third time. It is a figure which shows the example when a radiation detector moves to the imaging position (after the 2nd movement).

  Embodiments of a radiographic image capturing apparatus according to the present invention will be described below with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.

FIG. 1 shows a front view of a configuration example of a radiographic image capturing apparatus 1 according to the present embodiment, and FIG. 2 shows a side view of a configuration example of the radiographic image capturing apparatus 1.
As shown in FIGS. 1 and 2, the radiographic imaging apparatus 1 is provided with respect to a support base 2 in which a support base 3 is fixed to a floor surface F with bolts or the like. In the present embodiment, the support base 3 can be moved up and down in a substantially vertical direction with respect to the support base 2 by driving of a drive device such as a drive motor (not shown).

  In addition, although this embodiment demonstrates the case where the support stand 2 is fixed to the floor surface F, for example, it is also possible to reverse the top and bottom, and to fix the support stand 2 to the ceiling which is not shown in figure. is there. Further, for example, the support base 2 is fixed to a pedestal (not shown) provided with wheels or the like and movable on the floor surface, or a rail or the like is provided on the ceiling, and the support base 2 is suspended from the rail or the like. It is also possible to configure the support base 2 so that it can move relative to the floor or ceiling. Furthermore, it is also possible to configure the support base 2 in a columnar shape and to support the support base 3 up and down along the column.

  A support base shaft 4 is provided on the upper side surface of the support base 3 so as to extend in a substantially horizontal direction. The support base shaft 4 is fixed so as not to rotate in the circumferential direction of the support base shaft 4.

  The first arm 6 and the second arm 7 extend in a substantially vertical direction with respect to the support base shaft 4 at the end of the support base shaft 4 opposite to the support base portion 3 and extend in directions opposite to each other. Is attached.

  The first arm 6 and the second arm 7 are configured so that their lengths can be expanded and contracted with the support base shaft 4 as a base point. In the present embodiment, each of the first arm 6 and the second arm 7 is a telescopic type that slides a small piece of a cylinder, and the first arm driving unit and the second arm driving unit including a driving motor and the like, Each length is adjustable.

The distal end portion of the first arm 6 is provided with a radiation tube 10, and the distal end portion of the second arm 7 is provided with a holding base driving unit 5, a detector holding base 13, and a radiation detector 12. The distance R between the radiation tube 10 and the radiation detector 12 is variable by the expansion and contraction of the first arm 6 and the second arm 7. When the subject table 15 is provided between the radiation tube 10 and the radiation detector 12, the distance R1 between the radiation tube 10 and the subject table 15 and the distance R2 between the subject table 15 and the radiation detector 12 are also first. It can be changed by the expansion and contraction of the arm 6 and the second arm 7.
Therefore, the first arm driving unit and the second arm driving unit that drive the first arm 6 and the second arm 7 function as a first adjusting unit that adjusts the distance R1 and a second adjusting unit that adjusts the distance R2.

  In the present invention, the distance between the radiation tube 10 and the other member accurately represents the distance between the focal point of the radiation tube 10 and the other member. Moreover, the radiographic imaging device 1 should just be able to adjust distance R, R1, R2 correctly within the tolerance | permissible_range of an error, and is not limited to the said structure.

  That is, for example, the first arm 6 and the second arm 7 are each configured as a rod-like structure that does not expand and contract with the support base shaft 4 as a base point, and the radiation tube 10 and the radiation detector 12 are the rod-like first arm 6 and the second arm 7. It is also possible to configure to adjust the distances R, R1, and R2 by moving along the two arms 7.

  Each of the first arm 6 and the second arm 7 includes a position measurement system such as an encoder (distance acquisition means) for measuring the movement distances of the first arm and the second arm, respectively. The distances R, R1, and R2 can be acquired based on the values.

A first support shaft 8 extends so as to be substantially parallel to the support base shaft 4 at a tip portion of the first arm 6 opposite to the support base shaft 4. The radiation irradiator 9 is attached to be rotatable around the central axis of the first support shaft 8.
That is, as shown in FIG. 1, the radiation irradiator 9 can be rotated clockwise and counterclockwise around the first support shaft 8 when viewed from the front of the apparatus. The rotation of the radiation irradiator 9 around the first support shaft 8 is performed by driving a drive device such as a drive motor. The rotation of the radiation irradiator 9 around the first support shaft 8 may be configured to be manually performed by the photographer.

  The radiation irradiator 9 includes a radiation tube 10 serving as a radiation source for irradiating radiation, and a diaphragm unit 11 serving as a diaphragm unit for adjusting a radiation field at a radiation radiation port of the radiation tube 10. Means. The irradiation field of radiation can be set by adjusting the opening / closing amount (aperture amount) of the diaphragm unit 11. The radiation irradiator 9 is connected to a power supply unit (not shown) that supplies power to the radiation tube 10.

  Examples of the radiation tube 10 include a Coolidge X-ray tube and a rotary anode X-ray tube widely used in medical sites and nondestructive inspection facilities. In the rotary anode X-ray tube, radiation is generated when an electron beam emitted from the cathode collides with the anode. This is incoherent (incoherent) like natural light, and is not divergent X-rays but divergent light. If the electron beam continues to hit the place where the anode is fixed, the anode will be damaged by the generation of heat. Therefore, in a commonly used radiation tube, the anode is rotated to prevent a decrease in the life of the anode. The electron beam is made to collide with the surface of the anode having a certain size, and the generated radiation is emitted toward the subject H from the plane of the anode with the certain size. The size of the plane viewed from the irradiation direction (subject direction) is called the actual focus (focus). The focal diameter (μm) can be measured by the method defined in (2.2) slit camera of 7.4.1 Focus test of JIS Z 4704-1994. Needless to say, the optional selection conditions in this measurement method can be measured with higher accuracy by selecting the conditions that give the highest accuracy in consideration of the measurement principle according to the nature of the radiation source.

  The radiation tube 10 can set the focal diameter within a large focal diameter range of 300 to 2000 μm for close-contact photography and a small focal diameter range of 10 to 300 μm for phase contrast photography. Moreover, they are configured to be switched by operating the operating device 16 (see FIG. 2). The range of the small focal diameter is more preferably in the range of 50 to 140 μm. Further, it is more preferable that the maximum current value is provided depending on the size of the focal diameter.

  More specifically, the smaller the focal diameter of the radiation tube 10 is, the clearer the phase contrast image is obtained. However, since the maximum output current value is small, there is a problem that the photographing time becomes long. For this reason, the preferred focal spot size is determined by the region to be imaged. A relatively thin part such as a finger or a foot can reduce the original irradiation dose, so that the output may be relatively low, and it is preferable to select a small focus that emphasizes sharpness. Specifically, a range of 10 to 140 μm is preferable. Since the elbows and knees have a little thickness, they require a higher output than fingers and preferably have a slightly larger focal diameter. Specifically, a range of 50 to 200 μm is preferable. For thick parts such as the chest, abdomen, and lumbar vertebrae, high output is required, so that a large focal diameter is required. Specifically, the range of 100 to 300 μm is preferable. For thick parts, in addition to increasing the irradiation dose, in order not to increase the exposure dose, increase the tube voltage (increase the radiation energy), shorten the imaging distance (irradiation without increasing the exposure dose) It is also possible to cope with this by a method such as reducing the dose). In addition, there is a method of dealing with a thick part by close contact photographing.

  The radiation tube 10 is preferably one that emits radiation having an average energy of 14 to 60 keV. This is because when the average energy of the irradiated radiation is less than 14 keV, almost all of the irradiated radiation is absorbed by the subject, so that the exposure dose of the subject becomes very large, and clinical use is not preferable. In addition, if the average energy of radiation to be irradiated is greater than 60 keV, sufficient contrast cannot be obtained in bones and soft tissues constituting the human body, and the obtained radiographic image may be used for diagnosis or the like. This is because it may not be possible.

  As the radiation tube 10, for example, a Coolidge X-ray tube such as a rotating anode X-ray tube widely used in the medical field is preferably used. At that time, W (tungsten) used in general imaging, Mo (molybdenum) and Rh (rhodium) used in mammography are preferably used for the target (anode) of the radiation tube. In particular, when W is used as a target, radiations with tube voltage set values of 30, 50, 100, and 140 kVp and average energies of 22, 32, 47, and 60 keV, respectively, are normally irradiated.

  Thus, when W (tungsten) is used as the target of the radiation tube, the tube voltage can be set within a range of 30 to 140 kVp, the current value is set to 1 to 300 mA, and the imaging time is set within a range of 1 millisecond to 10 seconds. It becomes. The upper limit value of the current value tends to be lower as the focal diameter is smaller. When the focal diameter is 100 μm, the upper limit value is about 40 to 50 mA.

  In the radiographic imaging apparatus 1, in addition to imaging of joint diseases represented by rheumatism, most of them are soft tissue, and mammography that requires detection of fine calcification, most of bone is cartilage. When performing pediatric imaging or the like, among the above-mentioned radiation energies, the sharpness is improved by the phase contrast effect and the diagnostic ability is improved particularly by irradiation with low radiation energy (set to a low tube voltage). Therefore, when performing phase contrast imaging, the average energy of the irradiated radiation is preferably 14 to 32 keV.

  More specifically, the lower the tube voltage (radiation energy), the higher the contrast and the discrimination ability, but there is a problem that the exposure dose increases. Therefore, a preferable tube voltage is determined depending on the part to be imaged. A relatively thin portion such as a finger or a foot can reduce the original irradiation dose, and therefore it is preferable that the tube voltage is relatively low. Specifically, a range of 20 to 50 kVp (18 to 32 keV) is preferable. Elbows and knees are somewhat thicker and require a higher tube voltage than fingers. Specifically, a range of 30 to 60 kVp (22 to 35 keV) is preferable. High tube voltage is required for thick parts such as the chest, abdomen, and lumbar spine. Specifically, a range of 50 to 140 kVp (32 to 60 keV) is preferable.

  When performing phase contrast imaging, if the focal diameter of the radiation tube 10 is set to 1 μm or more as described above, radiation within the above average energy range can be irradiated and practical output intensity can be obtained. In order to obtain sufficient radiation intensity, the focal diameter is preferably 50 μm or more.

  The radiation tube 10 is not limited to a cooling ridge X-ray tube such as the above-described rotating anode X-ray tube as long as these conditions are satisfied, and may be a microfocus X-ray source or the like.

  A holding base drive unit 5 is extended at the tip of the second arm 7 opposite to the support base shaft 4 so as to be substantially parallel to the subject base 15. The holding table driving unit 5 is a holding table moving unit that moves a detector holding table 13 that holds the radiation detector 12 substantially parallel (horizontal direction) to the subject table.

  As the radiation detector 12, any system of an analog system using a screen or a film and a digital detector system for detecting a radiation dose as digital information may be used, and it is not necessary to use a film or the like to process data. An easy-to-use digital detector system is preferably used. A radiation detector using an FPD (Flat Panel Detector), CR (Computed Radiography), or CCD (Charge Coupled Device) that detects the radiation dose as digital information for each pixel is preferably used, and particularly excellent as a two-dimensional image sensor. FPD is preferred. The pixel size is preferably 10 to 200 μm, more preferably 50 to 150 μm.

  In the present embodiment, a radiation detector using FPD is used as the radiation detector 12. FIG. 3 shows a configuration example of the radiation detector 12. As shown in FIG. 3, the radiation detector 12 is configured by connecting a panel 12a, a detector control unit 12b, and the like via a bus. The radiation detector 12 detects a radiation amount emitted from the radiation tube 10 and transmitted through the subject H, and outputs the radiation amount as radiation image data to an image processing apparatus (not shown).

  The size of the panel 12a of the radiation detector 12 is appropriately selected. In FIG. 3, a cassette type radiation detector is shown as the radiation detector 12, but a so-called stationary type formed integrally with the detector holding base 13 can also be used.

  In the present embodiment, a phototimer (not shown) that detects the amount of radiation that has passed through the subject H is provided below the radiation detector 12, that is, on the opposite side of the radiation detector 12 (not shown). When the amount of radiation that has passed through the subject H reaches a predetermined dose, the phototimer transmits a signal for stopping irradiation of radiation from the radiation tube 10 to a control device (to be described later) of the radiation imaging apparatus 1. It has become. In the case where the radiation detector 12 is the FPD described above, the FPD itself may be configured to have a function of detecting a signal instead of a phototimer.

  In addition, the lower side of the radiation detector 12, the inside of the detector holding base 13, and the like are configured by lead or the like that shields radiation in order to prevent radiation exposure to the human body below the radiation detector 12. A radiation shielding member is provided.

  When performing close-contact imaging, for example, a radiation detector 12 provided with a grid 12c for absorbing and removing radiation scattering components on the top side of the panel 12a as shown in FIG. 3 can be used. is there. However, when the grid 12c is used, the amount of radiation incident on the panel 12a of the radiation detector 12 is reduced. Therefore, it is preferable not to use the grid 12c when the grid 12c is not necessary, particularly in the case of phase contrast imaging. Normally, the grid 12c is not used. Therefore, the grid 12c can be configured to be detachable from the radiation detector 12.

  A plate-like subject table 15 for fixing the position of the subject H is attached to the end of the support base shaft 4 opposite to the support base portion 3 so as to extend in the extending direction of the support base shaft 4. The subject table 15 is made of a material having excellent radiation transparency such as carbon, or is made hollow, for example, so as not to reduce the radiation transmittance as much as possible. It is also possible to configure the subject table 15 with a honeycomb structure carbon plate or the like. In addition, for example, in order to fix the subject's hand that is the subject H so as not to move during photographing, the subject table 15 is formed of resin or the like, and the hand is placed on the surface portion of the subject table 15 on which the subject's hand is placed. It is also possible to form irregularities in the shape. The unevenness made of the resin or the like may be placed on a subject table such as a carbon plate.

  In the present embodiment, the subject table 15 can be detachably attached to the support base shaft 4 via a mounting jig (not shown), and the subject table 15 is attached to the support base portion 4 via the support base shaft 4. It moves up and down in accordance with the up and down of 3.

  Instead of making the subject table 15 attachable to and detachable from the support base shaft 4 as in this embodiment, for example, the subject table 15 is attached to the support base shaft 4 in FIG. The optical path of the radiation from the radiation tube 10 toward the radiation detector 12 is obstructed by being configured to be able to stand up and down in the vertical direction or to be configured to be able to fold the subject table 15. It is also possible to configure so that the subject table 15 can be moved to a position that does not exist.

  The subject table 15 is provided with a compression plate (not shown) that presses and fixes the subject H appropriately from above, if necessary. The subject's legs and the like are located below the subject table 15 to detect radiation. A protector (not shown) or the like is provided as appropriate so that the camera 12 can be brought to the photographing position without being exposed to radiation while preventing the container 12 from being hit.

  As shown in FIG. 2, an operation device 16 is connected to the radiation image capturing apparatus 1. The operation device 16 includes an input unit 16a including a keyboard for inputting instructions such as imaging conditions to the radiographic imaging device 1, and a display including a CRT (Cathode Ray Tube) display for displaying the imaging conditions and the like. A portion 16b is provided. Tube voltage, irradiation time, imaging conditions, and the like can be set by the input unit 16a.

  FIG. 2 shows a case where the operating device 16 is installed in the same room as the device main body. However, for example, the operating device 16 is provided in a separate room, and the operating device 16 and the device main body are provided. It can also be configured to connect via a LAN (Local Area Network) or the like.

  In the operation device 16, a control device for making various settings for the radiographic imaging device 1 and controlling its operation is incorporated. The control device is configured by a computer in which a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like (not shown) are connected by a bus.

  FIG. 4 is a block diagram showing a control configuration of the radiation image capturing apparatus 1 according to the present embodiment. As shown in FIG. 4, the radiographic image capturing apparatus 1 detects the radiation amount that has passed through the subject H and the operating device 16 including the control device 20, the power supply unit 21, the input unit 16 a, the display unit 16 b, and the image memory 22. A phototimer 23, an irradiation drive unit 24 for adjusting the operation of the radiation irradiator 9, a first arm drive unit 25 for driving the first arm 6, a second arm drive unit 26 for driving the second arm 7, It is comprised from the holding stand drive part 5 which drives the detector holding stand 13, various encoders 27 which measure the movement distance and position of each part, etc., and electric power is supplied to each part from the power supply part 21.

  In a memory such as a ROM of the control device 20, a control program and various processing programs for controlling each part of the radiographic image capturing device 1 are stored. The control device 20 reads out the control program and various processing programs from the memory based on the input of the operator input from the input unit 16a, and performs the operation of each unit of the radiographic imaging device 1 while displaying the control content on the display unit 16b. It is designed to control the entire system.

  Here, the principle of contact imaging and phase contrast imaging performed by the radiographic image capturing apparatus 1 according to the present embodiment will be briefly described. FIG. 5A shows an example of contact photographing, and FIG. 5B shows an example of phase contrast photographing.

  In close-contact imaging, as shown in FIG. 5 (A), subject H is detected with radiation removed with subject table 15 removed or moved to a position that does not obstruct the optical path of radiation from radiation tube 10 toward radiation detector 12. The image is taken in close contact with the container 12. In close-contact imaging, the focal diameter of the radiation tube 10 is normally set within the range of the large focal diameter of 300 to 2000 μm described above, and radiation having a current value larger than that of phase contrast imaging is irradiated to several tens of millimeters. Short-term radiography is performed for a few seconds to several hundred milliseconds.

  In close-contact imaging, as can be seen from FIG. 5A, the subject H is not enlarged, and the radiation detector 12 detects an image of the subject H of the same size.

  As described above, the close-contact imaging can be performed by irradiating the subject H with radiation having a large current value for a short time as compared with the phase contrast imaging, so that the subject H who is the subject H moves even if the body moves. No radiographic images can be obtained.

  Further, in the soft tissue having a low density in the body of the subject, the difference in the refractive index of the radiation from the surrounding portion is small, so that the edge portion tends to become unclear. Due to the large focal diameter and the scattering of radiation within the panel 12a of the radiation detector 12, the edge portion becomes further unclear, and it is difficult to photograph soft tissue clearly. In this case, although it is possible to provide a grid 12c on the top plate side of the panel 12a of the radiation detector 12 to absorb and remove the radiation scattering component, the amount of radiation incident on the panel 12a is reduced accordingly. As described above.

  On the other hand, in phase contrast imaging, the subject H is arranged between the radiation tube 10 and the radiation detector 12 by providing a subject table 15 as shown in FIG. That is, in FIG. 1, the distance R2 between the subject table 15 and the radiation detector 12 is arranged to have a predetermined distance that is not 0 m.

FIG. 6 is a diagram for explaining the principle of phase contrast imaging. 6A is a diagram for explaining the radiation refracted at the edge portion of the subject, and FIG. 6B is a diagram for explaining the radiation intensity that is strongly detected at the edge portion of the subject.
When the subject H is arranged as shown in FIG. 5B, the radiation that has entered the subject H is close to the edge of the subject H as opposed to a normal glass lens, as shown in FIG. 6A. Refracts outward. Therefore, when the radiation reaches the radiation detector 12, the radiation refracted at the portion close to the edge of the subject H overlaps with the radiation that has passed through the edge portion of the subject H, and as shown in FIG. In the detector 12, the radiation that reaches the edge portion of the subject H becomes dense, and the radiation intensity in that portion becomes strong. On the contrary, in the radiation part that has passed through the inner part far from the edge of the subject H, the radiation becomes sparse and the radiation intensity in that part becomes weak. In this way, in phase contrast imaging, the detected radiographic image becomes an image in which the edge portion of the subject H, particularly the edge portion of the soft tissue of the subject's body existing at the edge portion of the subject H is emphasized.

  Further, in phase contrast imaging, not only the edge portion of the entire soft tissue of the subject H is emphasized as described above, but also the same edge enhancement is performed at the boundary portion where the refractive index is different from the surrounding portion inside the soft tissue. The effect of. Therefore, all the components such as bone, cartilage, and joint fluid existing in the joint part of the human body have different refractive indices with respect to radiation. Therefore, by emphasizing their edges by phase contrast imaging, An image with a clear boundary can be obtained.

  In this embodiment, as shown in FIG. 5B and FIG. 2, the radiation irradiated from the radiation tube 10 uses radiation that spreads in a cone beam shape as the distance from the radiation tube 10 increases. Therefore, in phase contrast imaging, an enlarged image of the subject H placed and fixed on the subject table 15 can be obtained.

As shown in FIG. 1, the enlargement ratio M with respect to an image (life size) in the case of an enlarged image taken at the same magnification is a distance R1 between the radiation tube 10 and the subject table 15 and between the subject table 15 and the radiation detector 12. When the distance is R2,
M = (R1 + R2) / R1 (1)
Given in. If the distance R between the radiation tube 10 and the radiation detector 12 is used, the equation (1) is
M = R / R1 (2)
Can also be expressed.

  The enlargement ratio M is determined by an appropriate size depending on a region to be imaged or a size to be imaged for the region. If an attempt is made to photograph the entire large part such as the chest and abdomen, close-contact photography at the same magnification is required. However, in the case of fingers and feet, even when the whole is photographed, magnified photographing with an enlargement ratio of about 1.2 to 2 times is possible, and it is easy to obtain a phase contrast image. In addition, in the case of the chest and abdomen as well as in the case of fingers and toes, when photographing a part of those parts, it is a part of the part by an enlarged spot photographing of about 2 to 5 times. A very clear image can be obtained.

  The radiation is partially scattered by the subject H, and if the distance R2 between the subject table 15 and the radiation detector 12 is small, that is, if the subject H and the radiation detector 12 are close to each other, the scattered radiation from the subject H is radiation. It reaches the detector 12 and reduces the contrast of the radiation image. In order to solve this problem, the grid 12c may be provided on the panel 12a of the radiation detector 12, but in this embodiment, the distance R2 between the subject table 15 and the radiation detector 12 is set to be a certain distance or more. By setting, that is, by providing an air gap, the scattered radiation does not leak out of the radiation detector 12 and reach the radiation detector 12.

  In phase contrast imaging, when the distance R2 between the subject H and the radiation detector 12 is large, the image enlargement ratio is also large, and the edge enhancement effect is also large. Further, the edge enhancement effect is different depending on the tube voltage applied to the radiation tube 10. The higher the tube voltage applied to the radiation tube 10, the smaller the edge enhancement effect becomes, and the edge enhancement effect is applied to the radiation tube 10. The edge enhancement effect increases as the tube voltage decreases.

  Therefore, in phase contrast imaging, the tube voltage applied to the radiation tube 10 is set lower than that in close-contact imaging, and the focal diameter of the radiation tube 10 is set within the above-described small focal diameter range of 10 to 300 μm. . The upper limit of the radiation field is the distance R1 from the radiation tube 10 to the subject table 15, the distance R2 from the subject table 15 to the radiation detector 12, that is, the magnification M, and the area of the panel 12a of the radiation detector 12. And determined by

  However, in the phase contrast imaging, the radiation that is weaker than that in the case of the close-contact imaging is used as described above, so that the imaging time of the radiography is relatively long. For this reason, if the subject's body, which is the subject H, moves during that time, the captured radiographic image is easily blurred.

  Note that the setting of imaging conditions in phase contrast imaging is comprehensively disclosed in Japanese Patent Application Laid-Open No. 2002-162705, so please refer to it in detail. A brief description is given below.

  As described above, in the phase contrast image, the distance from the focus of the radiation tube 10 to the subject table 15 (subject H) is R1, the distance from the subject table 15 (subject H) to the radiation detector 12 is R2, and the focal diameter is the same. When D is set, the image can be obtained by photographing so as to satisfy the conditions of 0.1 ≦ R1, 0.3 ≦ R2, and D ≦ 0.3 (mm). In this embodiment, as described above, the distance R between the radiation tube 10 and the radiation detector 12 is also variable. However, when the setting of the distance R is limited, such as in a photographing room, the distance R It is possible to shoot under optimal conditions by fixing R and changing the ratio of the distances R1 and R2 within the fixed distance R. For example, when R = 3.0 (m) is determined, for this distance R, R1 = 1.0 (m) and R2 = 2.0 (m). Considering the size of a general photography room, the range is 0.1 ≦ R1 ≦ 2.0, 0.3 ≦ R2 ≦ 2.0, 0.8 ≦ R ≦ 3.0, and the enlargement ratio M is 1. .5 ≦ M ≦ 10, and the focal diameter D is in the range of 0.005 (mm) ≦ D ≦ 0.2 (mm). The optimum distances R, R1, and R2, the enlargement ratio M, and the focal diameter D may be determined.

  By setting the focal spot diameter D in such a range, the radiation intensity is strong, imaging can be performed for a short time, and motion blur due to movement of the subject H can be reduced. More preferable distances satisfy the ranges of 0.5 ≦ R1 ≦ 1.2, 0.5 ≦ R2 ≦ 1.2, 1.0 ≦ R ≦ 2.4, and the enlargement ratio M is 3 ≦ M ≦ 8. The focal diameter D can be set to satisfy the range of 0.03 (mm) ≦ D ≦ 0.14 (mm).

  The control device 20 of the radiographic imaging device 1 according to the present embodiment controls the operation of each device and each member so as to take advantage of the features of the close contact imaging and the phase contrast imaging as described above.

  More specifically, the control device 20 is set with a shooting method for performing shooting by close contact shooting, phase contrast shooting, or long shooting through the input unit 16a of the operation device 16. It has become.

  When close-contact imaging is set as the imaging method, the control device 20 changes the focal diameter of the radiation tube 10 to a focal diameter set in advance within a large focal diameter range of 300 to 2000 μm as described above. In addition, since the subject table 15 is not removed or moved, and the optical path of radiation from the radiation tube 10 toward the radiation detector 12 is blocked by the subject table 15, the control device 20 displays the display unit of the operation device 16. The photographer is alerted by displaying a warning on 16b or issuing a warning by voice.

  In this embodiment, when close-contact shooting is set as the shooting method, a setting screen for numerical values to be input is displayed on the display unit 16b of the operation device 16, and the photographer sets the input unit 16a. To set those values.

  The values set in the close-contact imaging include, for example, an imaging region of the subject's body as the subject H, a distance R between the radiation tube 10 and the radiation detector 12, and a radiation detector in which the radiation detector 12 is a cassette type fitting type. In the case of, the type and the like are listed.

  Also, the shooting direction is set. That is, an angle when the radiation direction when the radiation is irradiated from the radiation tube 10 toward the radiation detector 12 directly below the vertical direction is, for example, 0 degrees is set by the photographer via the input unit 16a.

  When the distance R between the radiation tube 10 and the radiation detector 12 and the imaging direction are set by the photographer, the control device 20 drives each drive unit while checking the values of the various encoders 27 to set the position of each member. adjust. Specifically, in the present embodiment, the control device 20 adjusts the distance between the radiation tube 10 and the radiation detector 12 to the set distance R by expanding and contracting the first arm 6 and the second arm 7.

  Further, the control device 20 reads the area of the panel 12a from the memory in accordance with the type of the radiation detector 12 installed in advance or the fitted radiation detector 12, and the read area, the radiation tube 10 and the radiation detector 12 are read out. The radiation field of the radiation is calculated from the distance R to, and the opening / closing amount of the diaphragm unit 11 of the radiation tube 10 is determined so as to realize the irradiation field, and the opening / closing amount of the diaphragm unit 11 is determined. Adjust as follows. The irradiation field is set so as not to spread beyond the upper limit value determined by the above, but can be set as narrow as necessary.

  Further, a table for determining the correlation between the distance R, the imaging region, the focal diameter of the radiation tube 10 and the imaging conditions, that is, the tube voltage and the irradiation dose (mAs value), is created in advance and stored in the memory. When the imaging region is input as described above and the distance R and the focal diameter of the radiation tube 10 are determined, the tube voltage to be applied to the radiation tube 10 and the irradiation dose to be irradiated are determined with reference to the table. The irradiation time of radiation is determined by the current flowing through the radiation tube 10 and the irradiation dose.

  At the time of radiography, the control device 20 supplies power to the radiation tube 10 from the power supply unit 21 to irradiate the subject H with radiation. In addition, when the amount of radiation that has passed through the subject H reaches a predetermined dose and a signal is transmitted from the phototimer 23, the control device 20 stops supplying power from the power supply unit 21 to the radiation tube 10 and emits radiation. Stop irradiation. The radiation irradiation conditions are appropriately set in consideration of factors other than the radiation dose detected by the phototimer 23, that is, the type of the radiation detector 12, for example. Therefore, precisely, the control device 20 stops the radiation irradiation when a preset irradiation condition such as a signal transmitted from the phototimer 23 is satisfied.

  On the other hand, when phase contrast imaging is set in the setting of the imaging method, the control device 20 sets the focal diameter of the radiation tube 10 in the range of a small focal diameter of 10 to 300 μm in advance as described above. Change to diameter. When the subject table 15 is not attached, the control device 20 alerts the photographer by displaying a warning on the display unit 16b of the operation device 16 or issuing a warning by voice. It has become.

  In this embodiment, when phase contrast imaging is set as an imaging method, a setting screen for numerical values to be input is displayed on the display unit 16b of the operation device 16, and the photographer inputs the input unit 16a. To set those values.

  As the values set in the phase contrast imaging, as in the case of the close-contact imaging described above, the imaging direction, the imaging region of the subject's body as the subject H, and the radiation detector 12 in which the radiation detector 12 is a cassette type insertion type radiation detection. If it is a container, its type and the like can be mentioned.

  Further, as described above, since the magnification imaging can be performed in the phase contrast imaging, in this embodiment, when the imaging region is input, the control device 20 causes the display unit 16b of the operation device 16 to display an enlargement rate corresponding to the imaging region. The recommended value of M is displayed. In other words, in the present embodiment, the imaging region, the recommended value of the magnification M, the distance R1 between the radiation tube 10 and the subject table 15, the distance R2 between the subject table 15 and the radiation detector 12, and the focal point of the radiation tube 10 are stored in the memory. A table for determining the correlation with the diameter, the imaging condition, that is, the tube voltage and the irradiation dose (mAs value) is created and stored in advance. Note that the recommended value of the enlargement ratio M is appropriately set depending on the imaging region. Further, an upper limit value of the enlargement factor M is set for each imaging region so that the image to be imaged does not protrude from the radiation detector 12, and when the imaging region is input, the upper limit value of the enlargement factor M is also displayed. It is like that. Alternatively, the distances R1 and R2 that protrude from the image may not be set.

  When the recommended value of the enlargement ratio M is approved and set by the photographer, the control device 20 refers to the table and refers to the distance R1 or distance R2 corresponding to the imaging region and the focal diameter of the radiation tube 10. The tube voltage to be applied to and the irradiation dose to be irradiated are determined. Further, the control device 20 calculates the radiation field from the area of the panel 12a of the radiation detector 12 read from the memory and the relationship between the distance R1 and the distance R2, and the radiation so as to realize the radiation field. The opening / closing amount of the throttle part 11 of the tube 10 is adjusted. Further, the control device 20 adjusts the distances R <b> 1 and R <b> 2 by driving various driving devices while expanding and contracting the first arm 6 and the second arm 7 while checking the values of the various encoders 27.

  In the present embodiment, the photographer himself inputs the distance R1 between the radiation tube 10 and the subject table 15 and the distance R2 between the subject table 15 and the radiation detector 12, regardless of the recommended value of the magnification factor M. You can also do it. As described above, in phase contrast imaging, since the intensity of radiation emitted from the radiation tube 10 is weaker than that in close-contact imaging, there is a tendency that the imaging time of radiation imaging tends to be longer. If the distance R1 is shortened, shooting can be performed in a shorter time. The above configuration is for making the distance R1 and the distance R2 variable according to the judgment of the photographer.

  The memory also includes a table for the photographer to manually set the photographing conditions as described above. In the table, the distance R1, the distance R2 (or the enlargement ratio M), and the focal diameter of the radiation tube 10 are prepared. A correlation with imaging conditions (tube voltage, irradiation dose) is determined and created. In this table, in order to suppress blurring and geometrical unsharpness of a radiographic image to be captured, a maximum value of an enlargement factor M that can be set according to the focal diameter of the radiation tube 10 is set. When the enlargement factor M calculated from M or the distance R1 and the distance R2 according to the equation (1) is increased and reaches the maximum value, the focal point diameter of the corresponding radiation tube 10 becomes smaller at a further enlargement factor M. It is set as follows.

  In the present embodiment, the upper limit of the imaging time is set in advance depending on the imaging region. For example, if the imaging region is the heart, the heart moves fast, so if the imaging time is long, the captured radiographic image will be blurred. Therefore, for example, the upper limit of the imaging time is set to 1/20 to 1/30 seconds if the imaging region is the heart and 0.3 to 0.5 seconds if the imaging region is the hand. When the irradiation time of radiation calculated from the imaging conditions, that is, the imaging time exceeds the upper limit, the control device 20 displays a warning on the display unit 16b of the operation device 16 or issues a warning by voice. To alert you.

  Furthermore, for example, when the subject is very fat, the radiation transmittance decreases and the amount of radiation incident on the radiation detector decreases. Therefore, it is necessary to increase the tube voltage to shorten the imaging time. Therefore, in this embodiment, it is possible to input the body shape, weight, etc. of the subject via the input unit 16a of the operation device 16, and the control device 20 is able to input the body shape, weight, etc. of the subject created in advance. The tube voltage is raised according to a table that defines the correlation between the value and the rise value of the tube voltage.

  Further, if the thickness of the imaging region is thick, it is necessary to increase the tube voltage to shorten the imaging time, and it may be better to change the radiation dose to be irradiated depending on the age of the subject. As described above, the imaging conditions can be adjusted more finely according to the thickness, age of the subject, and the like.

  When the focal length of the radiation tube 10, the presence / absence of the subject table 15, the type or presence / absence of the radiation detector 12 are not normal, a warning is issued, or the grid 12c is not required to be disposed. Interlock control such as issuing a warning is appropriately performed. Needless to say, the reading gain of the radiation detector 12 can be adjusted by the distance R and the distances R1 and R2.

  When phase contrast shooting is set as the shooting method and further long shooting is set, a setting screen for numerical values to be input is displayed on the display unit 16b of the operation device 16, and the photographer can input the input unit. These values are set via 16a.

  In the long shooting, in order to shoot the entire long subject, the shooting region of interest of the subject is divided into a plurality of images, and the plurality of divided images are based on the overlapping region size W for image connection and the enlargement factor M. Are combined to obtain a long image.

Examples of values set in the long imaging include the imaging region of the subject's body as the subject H, and the type when the radiation detector 12 is a cassette-type fitting radiation detector. Further, in order to perform long imaging, the distances R1 and R2, the size of the subject H in the moving direction of the detector holding base 13 (the length of the imaging region of interest) A1, and the radiation detector 12 in the moving direction of the detector holding base 13 are used. Size B, overlapping area size W for image joining, and the moving direction of the radiation detector 12 during imaging are set. Therefore, the input unit 16a functions as a subject size acquisition unit, a distance acquisition unit, and a movement direction acquisition unit.
The distance acquisition means for acquiring the distances R1 and R2 may be an encoder that measures the movement distances of the first arm and the second arm.

  The overlapping area size W for image joining divides the imaging region of interest on the subject H surface in the moving direction of the detector holding base 13 into a plurality of regions, and retains the regions that overlap the divided adjacent imaging regions of interest. This is the length (width) of the table 13 in the moving direction. The overlapping region size W for image joining may be stored in advance in a memory in the control device 20.

  In setting the moving direction of the radiation detector 12 at the time of imaging, the photographer sets the direction away from the subject according to the imaging region. For example, when the range from the upper arm to the fingertip is the subject H, the direction from the upper arm to the fingertip is taken as the moving direction of the radiation detector 12 according to the position of the subject H fixed on the subject table 15. Set by the user.

  Similarly to the phase contrast imaging described above, when the imaging region is input, the control device 20 causes the display unit 16b of the operation device 16 to display a recommended value of the enlargement factor M corresponding to the imaging region. It may be.

  When various settings are made, the control device 20 refers to the table and performs irradiation with the tube voltage to be applied to the radiation tube 10 based on the distance R1 and the distance R2 corresponding to the imaging region and the focal diameter of the radiation tube 10. Determine the dose.

In addition, the control device 20 uses the radiation detector 12 based on the distances R1 and R2 acquired or input from the input unit 16a by the encoder that measures the moving distance of the first arm and the second arm. The magnification rate M of the image data of the subject H acquired by the above is calculated using the above formula (1) or (2). Then, the control device 20 determines the total number of movements n of the detector holder 13 based on the size B of the radiation detector 12 in the movement direction of the detector holder 13, the size A1 of the subject, and the magnification M. , The movement amount S1 of the detector holding base 13 for each movement up to n−1 times and the movement amount S2 of the detector holding base 13 for the final movement time n are calculated. Further, the control device 20 calculates the radiation irradiation field based on the position of the detector holder 13 for each movement, and the irradiation angle of the radiation irradiated from the radiation tube and the opening / closing amount of the diaphragm unit 11 (the diaphragm). Amount).
The control device 20 adjusts the position of the detector holding table 13 by the holding table driving unit 5, the irradiation angle and the amount of aperture by the irradiation driving unit 24 for each movement, and transmits the radiation irradiated from the radiation tube 10. Image data corresponding to the radiation is detected from the radiation detector 12 and stored in the image memory 22. Therefore, the control device 20 functions as a control unit.

7 and 8 are flowcharts of the long photographing operation in this embodiment.
The flowcharts shown in FIGS. 7 and 8 are processes executed by the cooperation of the control device 20 and each unit.

  The control device 20 acquires various setting values related to the long photographing, and stores them in a memory in the control device 20 (step S1). In step S1, the overlapping area size W for image joining, the size of the subject H in the moving direction of the detector holding base 13 (length of the region of interest for imaging) A1, and the size of the radiation detector 12 in the moving direction of the detector holding base 13 B, the moving direction of the radiation detector 12 during imaging is set by the input unit 16a and stored in the memory.

  The control device 20 acquires distances R1 and R2 input from an encoder or input unit 16a that measures the moving distance of the first arm and the second arm (step S2). And the control apparatus 20 calculates the expansion rate M using the said (1) Formula or (2) Formula based on distance R1, R2 (step S3).

The control device 20 acquires the overlapping area size W for image joining on the subject H plane in the moving direction of the detector holding base 13 from the memory (step S4), and enlarges it with the overlapping area size W for image joining on the subject H plane. Based on the rate M, the overlapping area size Wf for image joining on the surface of the radiation detector 12 in the moving direction of the detector holder 13 is calculated (step S5). The overlapping area size Wf for image joining on the surface of the radiation detector 12 can be calculated using the following equation (3).
Wf = M × W (3)

  The overlapping area size Wf for image joining on the surface of the radiation detector 12 is the overlapping width (the overlapping width for joining) with the image data adjacent in the moving direction of the detector holding base 13 in the image data detected every movement. And is calculated by equation (3).

Further, the control device 20 acquires the subject size A1 from the memory (step S6), and on the surface of the radiation detector 12 in the moving direction of the detector holder 13 based on the subject size A1 and the enlargement factor M. The shooting area size A2 is calculated (step S7). The imaging region size A2 on the surface of the radiation detector 12 can be calculated using the following equation (4).
A2 = M × A1 (4)

  The control device 20 acquires the size B of the radiation detector 12 in the moving direction of the detector holder 13 from the memory (step S8), and the size B of the radiation detector 12 is the imaging region size A2 on the surface of the radiation detector 12. It is determined whether or not this is the case (step S9).

  When the size B of the radiation detector 12 is equal to or larger than the imaging area size A2 on the surface of the radiation detector 12 (step S9; YES), the control device 20 can perform one imaging without moving the detector holding base 13. It is determined that the subject can be photographed (step S10), and the total number of movements n is set to 0 (step S11).

  When the size B of the radiation detector 12 is smaller than the imaging region size A2 on the surface of the radiation detector 12 (step S9; NO), the control device 20 moves the detector holding base 13 and divides the subject into a plurality of times. It is determined that it is necessary to shoot (step S12).

Based on the size B of the radiation detector 12 and the overlapping area size Wf for image joining on the surface of the radiation detector 12, the control device 20 performs the operation up to one time before the final movement (up to the movement number n−1). A moving amount S1 of the detector holding base 13 at each moving time is calculated (step S13). The movement amount S1 can be calculated using the following equation (5).
S1 = B−Wf (5)

Further, the control device 20 calculates the total number of movements n based on the imaging area size A2 on the surface of the radiation detector 12, the size B of the radiation detector, and the movement amount S1 (step S14). The total number of movements n can be calculated using the following equation (6).
n = ROUNDUP ((A2-B) / S1, 0) (6)

Furthermore, the control device 20 determines the final movement number (the number of movements is n) based on the imaging area size A2 on the surface of the radiation detector 12, the size B of the radiation detector, the movement amount S1, and the total movement number n. A moving amount S2 of the detector holding base 13 is calculated (step S15). The movement amount S2 can be calculated using the following equation (7).
S2 = A2-B- (S1- (n-1)) (7)

FIG. 9 shows a calculation example of the total number of movements n and the movement amounts S1 and S2 according to the enlargement ratio M.
FIG. 9 shows a calculation example when the subject size A1 is set to 50 cm, the size B of the radiation detector 12 is set to 30 cm, and the overlapping region size W for image joining is set to 0.5 cm.
As shown in FIG. 9, when the total number of movements n is 1, the final movement number is the first time, and therefore the (n-1) th movement amount is not set.

  Based on the total number of movements n and the movement amounts S1 and S2, the control device 20 determines the position of the detector holding table 13 at the start of imaging in the moving direction of the detector holding table 13 and the detector holding table after each movement. 13 positions (second and subsequent shooting positions) are calculated. Then, the control device 20 calculates an irradiation angle and a diaphragm amount at each photographing position (step S16).

  The length of the irradiation field on the surface of the radiation detector 12 in the moving direction of the detector holding base 13 is set so that the irradiation angle and the aperture amount do not irradiate radiation over a wider area than necessary according to the magnification M. It is calculated to be equal to the radiation detector size B.

The irradiation angle is, for example, an angle formed by a direction directly below the radiation tube 10 in the vertical direction (vertical direction) and a straight line connecting the radiation tube 10 and the center position of the radiation detector 12. In addition, let the direction which goes to the center position of the radiation detector 12 from the radiation tube 10 be an irradiation direction.
The irradiation angle is such that the position of the focal point of the radiation tube 10 and the position of the rotation axis of the first support shaft 8 are extremely close, and the radiation tube 10 is assumed to rotate around the focal point in a pseudo manner. It can be calculated by a trigonometric function or the like using the position and the distance R.

FIG. 10 shows a relationship diagram between the radiation tube 10 and the aperture 11.
The diaphragm unit 11 shown in FIG. 10 is an example in the case where the irradiation angle is 0 degree, that is, the irradiation direction G is a vertical line direction connecting the radiation tube 10 and the floor surface F. The diaphragm unit 11 is provided with diaphragm mechanisms 11 a and 11 b symmetrically at positions perpendicular to the irradiation direction G.
The aperture amount is the amount of movement of the aperture mechanism from a preset position, and is composed of the amount of movement dEr of one aperture mechanism and the amount of movement dEl of the other aperture mechanism. When the movement amounts dEr and dEl are both positive values, the aperture mechanisms 11a and 11b move in the direction in which the irradiation field is narrowed. When the movement amounts dEr and dEl are both negative values, the irradiation field is widened. The diaphragm mechanisms 11a and 11b move in the direction.

FIG. 11 is a conceptual diagram of adjustment of the irradiation angle and the aperture amount.
As shown in FIG. 11, the irradiation angle P is calculated according to the position of the radiation detector, and the irradiation field at the irradiation angle P matches the radiation detector size B based on the magnification rate M and the subject size A1. Thus, the movement amounts dEr and dEl of the diaphragm mechanism are calculated.
In addition, since the aperture | diaphragm | squeeze part 11 rotates around the center axis | shaft of the 1st support shaft 8 with the radiation tube 10, the positional relationship orthogonal to the irradiation direction G is maintained.

  FIG. 12 shows an example of the movement amount, irradiation angle, and aperture amount at each photographing position calculated in step S16. FIG. 12 shows the movement amount and irradiation angle at each imaging position when the distance R1 is 65 cm, the distance R2 is 49 cm, the magnification rate M is 1.75, the radiation detector size B is 30 cm, and the subject size A1 is 50 cm. An example of calculating the aperture amount will be shown. In this case, as shown in FIG. 9, it is assumed that the total number of movements n is 2, the movement amount S1 is 29.125 cm, and the movement amount S2 is 28.375 cm.

In FIG. 12, the movement amount (S0 = −28.750 cm) for the radiation detector 12 to move from the initial position to the imaging start position (number of movements N = 0) is calculated before the first imaging. As shown in FIG. 1, the initial position is a state where the center position of the radiation detector 12 is at a position directly below the focal point in the vertical direction. The movement amount S0 can be calculated using the following equation (8) based on the imaging region size A2 on the surface of the radiation detector 12 and the radiation detector size B. In addition, the positive / negative of the movement amount is a positive movement direction of the radiation detector 12 at the time of imaging.
S0 = (A2 / 2)-(B / 2) (8)

  Further, the irradiation angle P0 = 14.154 ° at the number of movements N = 0 is calculated, and the aperture amount (right aperture movement amount dEr0 = − is set so that the irradiation field at the imaging start position coincides with the radiation detector size B. 0.0778 cm, and left diaphragm movement amount dE10 = −0.2308 cm).

  The amount of movement of the detector holder 13 when moving from the imaging start position to the second imaging position (number of movements N = 1) is set to S1 = 29.125 cm. Then, the second imaging position is calculated, the irradiation angle P1 = −0.188 ° at the second imaging position is calculated, and the irradiation field at the second imaging position matches the radiation detector size B. In addition, the aperture amount (right aperture movement amount dEr1 = 0.0114 cm, left aperture movement amount dEl1 = −0.0337 cm) is calculated.

  The amount of movement of the detector holder 13 when moving from the second imaging position to the third imaging position (number of movements N = 2) is set to S2 = 28.375 cm. Then, the third imaging position is calculated, and the irradiation angle P2 = −14.154 ° at the third imaging position is calculated, so that the irradiation field at the third imaging position matches the radiation detector size B. In addition, the aperture amount (right aperture movement amount dEr2 = −0.0776 cm, left aperture movement amount dEl2 = 0.0035 cm) is calculated.

  After step S11 or after step S16, the control device 20 determines whether the total number of movements n is 0 (step S17).

  When the total number of movements n is 0 (step S17; YES), the control device 20 determines that the imaging is performed once without moving the detector holding base 13, and the magnification M and the focal point of the radiation tube 10 are determined. The tube voltage to be applied to the radiation tube 10 and the irradiation dose to be irradiated are determined based on the diameter. Further, the control device 20 calculates the irradiation field of the radiation according to the area of the panel 12a of the radiation detector 12 read from the memory and the magnification M, and the aperture of the radiation tube 10 so as to realize the irradiation field. The opening / closing amount of the part 11 is adjusted. And the control apparatus 20 starts irradiation of the radiation from the radiation tube 10, and image | photographs (step S18).

  The control device 20 acquires image data from the radiation detector 12 when imaging that satisfies a preset irradiation condition such as a signal transmitted from the phototimer 23 is completed (after step S18), and acquires the acquired image. The data is stored in the image memory 22 (step S19), an image based on the image data stored in the image memory 22 is displayed on the display unit 16b (step S20), and this process ends.

  When the total number of movements n is not 0 (step S17; NO), the control device 20 determines that the detector holding base 13 is moved to perform imaging a plurality of times, and the detector holding base 13 is moved after the start of imaging. The movement count value N for counting the number of times is set to 0 (step S21).

  The control device 20 moves the detector holder 13 by the movement amount S0 in the direction opposite to the moving direction of the radiation detector 12 at the time of imaging, and moves the radiation detector 12 from the initial position to the imaging start position (step). S22).

  Then, the control device 20 determines the tube voltage to be applied to the radiation tube 10 and the irradiation dose to be irradiated based on the magnification factor M and the focal diameter of the radiation tube 10. Further, the control device 20 adjusts the angle of the radiation tube 10 by moving the radiation irradiator 9 in the circumferential direction of the first support shaft 8 by the irradiation drive unit 24 based on the irradiation angle and the aperture amount at the imaging start position. In addition, the aperture movement amount of the aperture section 11 is adjusted (step S23).

  The control device 20 starts irradiation with radiation from the radiation tube 10 and performs imaging (step S24). When imaging that satisfies a preset irradiation condition such as a signal transmitted from the phototimer 23 is completed (after step S24), the control device 20 acquires image data from the radiation detector 12, and acquires the acquired image. Data is stored in the image memory 22 (step S25). Note that after the image data from the radiation detector 12 is stored in the image memory 22, the image data in the radiation detector 12 is reset with respect to the radiation detector 12.

  The control device 20 determines whether or not the movement count value N is equal to the total movement count n (step S26). If the movement count value N is not equal to the total movement count n (step S26; NO), the control device 20 adds 1 to the movement count value N (step S27).

  The control device 20 moves the detector holding base 13 to the Nth moving position in the moving direction of the radiation detector 12 during imaging (ie, moves the radiation detector 12 to the N + 1th imaging position) (step) S28).

  Then, the control device 20 determines the tube voltage to be applied to the radiation tube 10 and the irradiation dose to be irradiated based on the magnification factor M and the focal diameter of the radiation tube 10. Further, the control device 20 moves the radiation irradiator 9 in the circumferential direction of the first support shaft 8 by the irradiation drive unit 24 based on the irradiation angle and the aperture amount at the Nth moving position, that is, the N + 1th imaging position. Then, the angle of the radiation tube 10 is adjusted, and the diaphragm movement amount of the diaphragm unit 11 is adjusted (step S29). After step S29, the control device 20 proceeds to the process of step S24.

  When the movement number count value N is equal to the total movement number n (step S26; YES), the control device 20 uses the plurality of image data stored in the image memory 22 as an image joining overlapping region on the surface of the radiation detector 12. Bonding is performed using Wf to generate long image data (step S30).

  The control device 20 stores the generated long image data in the image memory 22 (step S31), and displays an image based on the long image data stored in the image memory 22 on the display unit 16b (step S32). The process ends.

FIG. 13 shows an example of the relationship between the radiation detector 12 and the radiation irradiator 9 at each imaging position.
In FIG. 13, the enlargement ratio M is 1.75, the total number of movements n is 2, the movement amount S1 is 29.125 cm, the movement amount S2 is 28.375 cm, and the irradiation angle and the movement amount at each photographing position are illustrated. 12 is an example in which the movement direction of the radiation detector 12 during imaging is a positive (+) direction.

  FIG. 13A shows an example in which the radiation detector 12 is arranged at the initial position. As shown in FIG. 13A, the initial position is such that the center position of the radiation detector 12 in the moving direction of the detector holding base 13 is a position directly below the radiation tube 10 in the vertical direction. In FIG. 13, in the movement direction of the detector holding base 13, the initial position with respect to the center position of the radiation detector 12 is indicated as 0, the right direction is positive (+), and the left direction is negative (−). Further, regarding the irradiation angle of the radiation tube 10, the rotation angle in the right direction around the radiation tube 10 is negative (−), and the rotation angle in the left direction is positive (+).

  FIG. 13B is an example when the radiation detector 12 is moved to the first imaging position (imaging start position). FIG. 13B shows a state in which the detector holding base 13 has moved from the initial position in the negative (−) direction by a movement amount S0 = −28.75 cm. At this time, the center position of the radiation detector 12 is −28.75. The radiation tube 10 is adjusted based on the irradiation angle P0 = 14.154 °, and the diaphragm unit 11 is adjusted based on the diaphragm movement amounts dEr0 = −0.0778 cm and dE10 = −0.2308 cm.

  FIG. 13C shows an example where the radiation detector 12 has moved to the second imaging position (after the first movement). In FIG. 13C, the detector holding base 13 is in a state where the movement amount S1 is 29.125 cm in the positive (+) direction from the imaging start position. At this time, the center position of the radiation detector 12 is +0.375. Further, the radiation tube 10 is adjusted based on the irradiation angle P1 = −0.188 °, and the diaphragm unit 11 is adjusted based on the diaphragm movement amounts dEr1 = 0.114 cm and dEl1 = −0.0337 cm.

  FIG. 13D shows an example in which the radiation detector 12 has moved to the third imaging position (after the second movement). In FIG. 13D, the detector holding base 13 is in a state where the movement amount S2 is 28.375 cm in the positive (+) direction from the imaging start position. At this time, the center position of the radiation detector 12 is +28.75. Further, the radiation tube 10 is adjusted based on the irradiation angle P2 = −14.154 °, and the diaphragm unit 11 is adjusted based on the diaphragm movement amounts dEr2 = −0.0776 cm and dEl2 = 0.0035 cm.

  As described above, according to the present embodiment, the detector holding that holds the radiation detector 12 for each movement calculated based on the size B of the radiation detector, the size A1 of the subject, and the enlargement ratio M. It is possible to detect the image data by moving the position of the table 13 and adjusting the irradiation angle and the aperture amount. Therefore, it is possible to efficiently perform radiography with a large magnification over a wide range and obtain a continuous radiographic image without forcing the subject to an unreasonable posture or unnecessary exposure. .

  In addition, since the detector holding base 13 can be moved every movement in the movement direction acquired by the input unit 16a, it is possible to take an image by moving the detector holding base in a direction away from the subject every movement. It is possible to prevent the subject from being exposed to unnecessary exposure.

  Furthermore, using the overlapping area Wf for image joining on the radiation detector surface calculated based on the enlargement factor M, the total number of movements n of the detector holding base 13 and the amount of movement of the detector holding base 13 for each movement time. S1 and S2 can be calculated. For this reason, when joining image data shot every movement, it is possible to prevent the loss of adjacent image data, and it is possible to prevent redundant exposure to the same position more than necessary.

  Further, the enlargement ratio M can be changed by adjusting the distance R1 or / and R2 by at least one of the first arm driving unit 25 and the second arm driving unit 26.

The radiation detector can detect image data from a phase contrast radiation image in which the contrast is enhanced by the edge effect of the subject, and image data with high sharpness can be obtained.
As a result, it is possible to easily synthesize a long image with higher accuracy than before, and to perform a highly reliable diagnosis.

  The present invention is not limited to the contents of the above-described embodiment, and can be appropriately changed without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Radiographic imaging apparatus 2 Support stand 3 Support base 4 Support base shaft 5 Holding stand drive part 6 First arm 7 Second arm 8 First support shaft 9 Radiation irradiator 10 Radiation tube 11 Diaphragm part 12 Radiation detector 12a Panel 12b Detection Control unit 12c Grid 13 Detector holding table 15 Subject table 16 Operation device 16a Input unit 16b Display unit 20 Control device 21 Power supply unit 22 Image memory 23 Photo timer 24 Irradiation drive unit 25 First arm drive unit 26 Second arm drive unit 27 Various encoders F Floor G Irradiation direction H Subject

Claims (6)

A radiation source that irradiates radiation; and a diaphragm unit that adjusts an irradiation field of radiation irradiated from the radiation source; and a radiation irradiation unit that irradiates a subject with radiation adjusted by the diaphragm unit;
An irradiation drive for adjusting the irradiation angle of the radiation from the radiation source by adjusting the radiation irradiation means about an axis extending in the horizontal direction and adjusting the amount of the irradiation field by the diaphragm means Means,
Movable detector holding means for holding a radiation detector for detecting image data from the transmitted radiation of the subject;
A holding table moving means for moving the detector holding means in a substantially horizontal direction;
A subject table for holding the subject provided between the radiation irradiating means and the radiation detector;
Subject size acquisition means for acquiring the size of the subject in the moving direction of the detector holding means;
Distance acquisition means for acquiring a distance between the radiation source and the subject table and a distance between the subject table and the radiation detector;
Calculating an enlargement ratio M of the image data of the subject acquired by the radiation detector based on the distance acquired by the distance acquisition means;
Based on the size of the radiation detector in the moving direction of the detector holding means, the size of the subject, and the enlargement ratio, the number of movements of the detector holding means and the detector holding means for each movement time Calculate the amount of movement,
Calculate the irradiation angle of the radiation from the radiation source for each movement and the aperture amount of the radiation field by the diaphragm means for each movement,
For each movement, the position of the detector holding means by the holding table moving means and the irradiation angle and the amount of aperture by the irradiation driving means are adjusted so that the radiation transmitted from the radiation source is transmitted. Control means for detecting the corresponding image data from the radiation detector;
Providing
A radiographic imaging device characterized by the above. A moving direction acquisition means for acquiring a moving direction of the detector holding means;
The control means includes
Moving the detector holding means by the holding stand moving means for each movement in the moving direction acquired by the moving direction acquiring means;
The radiographic imaging apparatus according to claim 1. The control means includes
Based on the enlargement ratio, calculate the overlapping width for joining the image data in the moving direction of the detector holding means,
Based on the calculated overlapping width for joining image data, the size of the radiation detector in the moving direction of the detector holding means, the size of the subject, and the magnification, the movement of the detector holding means Calculating the number of movements and the amount of movement of the detector holding means for each movement,
The radiographic imaging device according to claim 1 or 2. First adjusting means for adjusting a distance between the radiation source and the subject table;
Second adjusting means for adjusting the distance between the object table and the radiation detector;
Providing
The radiographic image capturing apparatus according to claim 1, wherein The radiation detector is
Detecting image data from a phase contrast radiation image enhanced by an edge effect of the subject;
The radiographic image capturing apparatus according to claim 1, wherein A distance acquisition step of acquiring a distance between a radiation source that irradiates radiation and a subject table that holds the subject, and a distance between the subject table and a radiation detector that detects image data from the transmitted radiation of the subject;
A subject size acquisition step of acquiring a size of the subject in a moving direction of a movable detector holding means for holding the radiation detector;
An enlargement ratio calculating step of calculating an enlargement ratio of the image data of the subject acquired by the radiation detector based on the distance acquired by the distance acquiring step;
Based on the size of the radiation detector in the moving direction of the detector holding means, the size of the subject, and the enlargement ratio, the number of movements of the detector holding means and the detector holding means for each movement time A movement amount calculating step for calculating a movement amount;
An irradiation drive amount calculation step of calculating an irradiation angle of the radiation from the radiation source for each movement and an aperture amount of the radiation field for each movement; and
The position of the detector holding means, the irradiation angle, and the aperture amount are adjusted each time the movement is performed, and image data corresponding to the transmitted radiation of the radiation emitted from the radiation source is detected from the radiation detector. A drive control process,
Including,
A radiographic imaging method characterized by the above.

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