JP2020065696A - Medical ct imaging apparatus, medical ct imaging method, program, and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for performing CT imaging with an X-ray irradiation amount suitable for a subject to be CT imaging. A profile selection unit 805 selects a control profile 830 corresponding to a photographing region ROI from a plurality of control profiles 830 for controlling an X-ray irradiation amount. The transmission information generation unit 806 generates transmission information 832 regarding the transmission of X-rays for the subject M1. The profile changing unit 807 generates an individual control profile 834 from the control profile 830 selected by the profile selection unit 805 based on the transparency information 832 generated by the transparency information generation unit 806. The irradiation control unit 803 controls the amount of X-ray irradiation to the subject M1 based on the individual control profile 834. [Selection diagram] FIG. 12

Description

  The present invention relates to a technique for performing CT imaging, and particularly to a technique for controlling an X-ray irradiation amount with respect to a subject.

  2. Description of the Related Art In the field of medical X-ray diagnosis, an X-ray CT imaging apparatus for tomographically imaging a human body is known. In the X-ray CT imaging apparatus, the X-ray generator and the X-ray detector are rotated by 180 ° or more around the subject, and X-ray projection images, which are projection images of X-rays from each direction, are acquired. . Then, the tomographic image at an arbitrary position is generated by computer-processing the obtained X-ray projection image.

  An X-ray high absorption site such as a cervical spine exists inside the subject. The high X-ray absorption site significantly weakens the X-ray intensity detected by the X-ray detector, so that the amount of information relating to X-ray transmission (or X-ray absorption) is reduced. Therefore, in Patent Document 1, the position of an X-ray high absorption site (specifically, the cervical spine) that may affect the CT imaging result is specified, and the control for controlling the X-ray irradiation dose according to the position is specified. Generating a model is described.

JP, 2010-75682, A

  By the way, the susceptibility to X-rays differs depending on the subjects to be CT-examined. For example, infants or growing children are considered to be more sensitive to X-rays (ie, less sensitive to X-rays) because they have a higher frequency of cell division than adults. Therefore, it is desirable to reduce the X-ray irradiation amount as much as possible. On the other hand, generally, the larger the physique, the smaller the X-ray transmittance. Therefore, the small amount of X-ray irradiation may reduce the amount of information regarding X-ray transmission that the X-ray projection image has.

  According to the technique of Patent Document 1, although it is possible to control the X-ray irradiation amount for the high X-ray absorption site, since the X-ray sensitivity is different for each subject as described above, X-ray irradiation suitable for the subject It was difficult to perform CT imaging in volume.

  Therefore, it is an object of the present invention to provide a technique for performing CT imaging with an X-ray irradiation amount suitable for a subject who is a CT imaging target.

  In order to solve the above problems, a first aspect is a medical CT imaging apparatus, which includes an X-ray generator that generates an X-ray cone beam, and an X-ray cone beam that detects the X-ray cone beam from the X-ray generator. A ray detector, a support portion for supporting the X-ray generator and the X-ray detector in opposition to each other, and the support portion in a state where a subject is arranged between the X-ray generator and the X-ray detector. A swivel driving unit that swivels around a predetermined swivel axis, a storage unit that stores a plurality of control profiles for controlling the X-ray irradiation amount according to a local imaging region that is a part of the subject, and the local imaging The area setting reception unit that receives the setting of the area, the profile selection unit that selects the control profile corresponding to the local imaging area that the area setting reception unit receives from the plurality of control profiles, and the subject Of the X-ray irradiation amount to the subject based on the transmission information generation unit that generates transmission information regarding transmission of X-rays, the control profile selected by the profile selection unit, and the transmission information generated by the transmission information generation unit. And a control unit for controlling.

  A second aspect is the medical CT imaging apparatus of the first aspect, wherein the transmission information is information regarding X-ray transmission of the local imaging region received by the region setting reception unit.

  A third aspect is the medical CT imaging apparatus of the first aspect or the second aspect, wherein the transmission information is information indicating the distribution of the X-ray high absorption region.

  A fourth aspect is the medical CT imaging apparatus according to any one of the first to third aspects, further comprising a region size setting reception unit that receives a setting of the size of the local imaging region of the subject, The control unit selects the control profile according to the size of the local imaging region received by the region size setting reception unit.

  A fifth aspect is the medical CT imaging apparatus according to any one of the first to fourth aspects, wherein the transmission information generation unit outputs the X-ray detector in X-ray imaging of the subject performed in advance. The transparency information is generated from the output data.

  A sixth aspect is the medical CT imaging apparatus according to any one of the first aspect to the fifth aspect, wherein the transmission information generation unit calculates the transmission information from a pixel value output by the X-ray detector in a pixel unit. To generate.

  A seventh aspect is the medical CT imaging apparatus according to any one of the first to sixth aspects, wherein the transmission information generation unit is configured to detect the X-ray while the rotation drive unit rotates the support unit. The transparency information is generated from output data output from the container.

  An eighth aspect is the medical CT imaging apparatus according to any one of the first to seventh aspects, wherein the transmission information generation unit generates the transmission information from the physique information that is information about the physique of the subject. .

  A ninth aspect is the medical CT imaging apparatus of the eighth aspect, wherein the transmission information generation unit captures the subject from one direction and a one-way scout image obtained by capturing the subject from two directions. The physique information is acquired from at least one image of the obtained bidirectional scout image and a panoramic image obtained by panoramic X-ray imaging of the subject.

  A tenth aspect is the medical CT imaging apparatus according to the eighth aspect or the ninth aspect, further comprising a communication unit that performs information communication with a database system in which medical information used for medical treatment of the subject is stored. The transparent information generation unit acquires the physique information from the medical care information acquired by the communication unit.

  An eleventh aspect is the medical CT imaging apparatus according to any one of the eighth to tenth aspects, further comprising: a subject holding unit that contacts the subject and holds the subject at a fixed position, The information generation unit acquires the physique information based on the position where the subject holding unit is in contact with the subject.

  A twelfth aspect is the medical CT imaging apparatus according to any one of the first to eleventh aspects, wherein the control unit limits a variation amount from the X-ray irradiation dose indicated by the control profile to within two times. Then, the amount of X-ray irradiation applied to the subject is controlled.

  A thirteenth aspect is the medical CT imaging apparatus according to any one of the first to twelfth aspects, wherein the control unit controls the X-ray so that the X-ray irradiation dose falls within a predetermined adjustment range. At least one of a tube current of the generator, a tube voltage, and a rotation speed of the support portion by the rotation drive portion is controlled.

  A fourteenth aspect is the medical CT imaging apparatus according to any one of the first to thirteenth aspects, wherein the area setting reception unit displays an illustration of a dental arch and the local imaging on the illustration. It includes an operation display panel that receives an operation for setting an area.

  A fifteenth aspect is the medical CT imaging apparatus of the eighth aspect, further comprising an informing unit that provides an indication of a pediatric physique when the physique information indicates a pediatric physique.

  A sixteenth aspect is the medical CT imaging apparatus of the fifteenth aspect, wherein the notification indicating the pediatric physique reduces the tube current supplied to the X-ray generator, reduces the tube voltage, and swivels the support portion. Is a display for instructing the operator to at least one of the reduction of the range, the acceleration of the rotation of the support portion, and the reduction of the size of the local imaging area.

  A seventeenth aspect is the medical CT imaging apparatus of the fifteenth aspect or the sixteenth aspect, wherein the profile selection unit selects a control profile for a child from the plurality of control profiles based on an operation input from an operator. The control unit controls the X-ray irradiation dose based on the child-specific control profile and the transmission information when the profile selection unit selects the child-specific control profile. .

  An eighteenth aspect is the medical CT imaging apparatus of the fifth aspect, wherein the X-ray imaging performed in advance is panoramic X-ray imaging for obtaining a panoramic image of the subject.

  A 19th aspect is the medical CT imaging apparatus of the 5th aspect, wherein the X-ray imaging performed in advance is bidirectional scout imaging to obtain a bidirectional scout image obtained by imaging the subject from two directions. .

  In a twentieth aspect, an X-ray generator that generates an X-ray cone beam, an X-ray detector that detects the X-ray cone beam from the X-ray generator, the X-ray generator, and the X-ray detector face each other. A medical CT including a supporting unit that supports the supporting unit and a swivel driving unit that swivels the supporting unit around a predetermined swivel axis in a state where an object is placed between the X-ray generator and the X-ray detector. A medical CT imaging method for performing CT imaging in an imaging apparatus, comprising: (a) preparing a plurality of control profiles for controlling an X-ray irradiation dose corresponding to a local imaging region that is a part of the subject. And (b) accepting the setting of the local imaging area, and (c) selecting a control profile corresponding to the local imaging area accepted in step (b) from the plurality of control profiles. , ( ) A step of generating transmission information on the transmission of X-rays of the subject, and (e) a step of rotating the support while irradiating the subject with an X-ray cone beam from the X-ray generator. Including, the step (e) controls the X-ray irradiation dose to the subject based on (e1) the control profile selected in the step (c) and the transmission information generated in the step (d). Including steps.

  A twenty-first aspect is a computer-readable program, and the CPU of the computer executes the program on a memory to cause the computer to execute the medical CT imaging method of the twentieth aspect.

  A twenty-second aspect is a computer-readable recording medium in which the program of the twenty-first aspect is recorded.

  According to the medical CT imaging apparatus of the first aspect, the X-ray irradiation dose is controlled based on the control profile according to the local imaging region and the transmission information according to the subject. Therefore, CT imaging can be performed with an X-ray irradiation amount suitable for the X-ray sensitivity of the subject.

  According to the medical CT imaging apparatus of the second aspect, since the X-ray irradiation amount is controlled based on the transmission information regarding the X-ray transmission of the local imaging region, CT imaging can be performed at a more suitable X-ray irradiation amount. it can.

  According to the medical CT imaging apparatus of the third aspect, since the X-ray irradiation amount is controlled according to the distribution of the X-ray high absorption region, CT imaging in which the influence of the X-ray high absorption region is reduced can be performed. .

  According to the medical CT imaging apparatus of the fourth aspect, since the control profile is selected according to the size of the local imaging area, CT imaging can be performed with an X-ray irradiation dose suitable for the size of the local imaging area. .

  According to the medical CT imaging apparatus of the fifth aspect, the transmission information is generated from the actual data output by the X-ray detector in the X-ray imaging performed in advance, and therefore, based on the X-ray transmittance of the actual subject, The amount of X-ray irradiation can be controlled.

  According to the medical CT imaging apparatus of the sixth aspect, the X-ray transmittance of the subject can be obtained from the pixel value.

  According to the medical CT imaging apparatus of the seventh aspect, since the transmission information is generated from the actual data output by the X-ray detector during imaging, the X-ray irradiation amount is controlled in real time according to the X-ray transmittance of the subject. it can.

  According to the medical CT imaging apparatus of the eighth aspect, it is possible to perform CT imaging with an X-ray irradiation dose according to the physique of the subject.

  According to the medical CT imaging apparatus of the ninth aspect, the physique information is generated from each X-ray image obtained by imaging the subject in advance, and therefore CT imaging is performed with an X-ray irradiation amount according to the physique of the subject. be able to.

  According to the medical CT imaging apparatus of the tenth aspect, the physique information is generated from the medical information of the subject, so that CT imaging can be performed with an X-ray irradiation amount according to the physique of the subject.

  According to the medical CT imaging apparatus of the eleventh aspect, the physique can be actually measured from the position where the subject holding unit comes into contact, and therefore CT imaging can be performed with an X-ray irradiation dose according to the physique of the subject.

  According to the medical CT imaging apparatus of the twelfth aspect, the amount of X-ray irradiation to the subject is suppressed within twice the amount of X-ray irradiation indicated by the original control profile, so that the X-ray exposure of the subject can be reduced.

  According to the medical CT imaging apparatus of the thirteenth aspect, since the X-ray irradiation amount is controlled so that it falls within the predetermined adjustment range, the exposure dose of the subject can be reduced.

  According to the medical CT imaging apparatus of the fourteenth aspect, the operator can intuitively set the local imaging area on the illustration.

  According to the medical CT imaging apparatus of the fifteenth aspect, since the operator is informed that the child's physique is present, the operator can perform CT imaging while paying attention to the exposure dose of the subject.

  According to the medical CT imaging apparatus of the sixteenth aspect, when the subject has a pediatric physique, the tube current is reduced, the tube voltage is reduced, the range of turning of the support portion is reduced, and the turning of the support portion is performed for the operator. Can be accelerated or the size of the local imaging area can be reduced. As a result, the exposure dose of the subject can be reduced.

  According to the medical CT imaging apparatus of the seventeenth aspect, the X-ray irradiation amount is controlled based on the child-specific control profile corresponding to the child and the transmission information according to the object having the child physique. Therefore, it is possible to perform CT imaging with an X-ray irradiation amount suitable for a subject having a pediatric physique.

  According to the medical CT imaging apparatus of the eighteenth aspect, the X-ray imaging performed in advance is the panoramic X-ray imaging for obtaining the panoramic image of the subject. Therefore, a panoramic image of a subject that is often photographed at the beginning of dental treatment can be used for positioning and can be effectively used.

  According to the medical CT imaging apparatus of the nineteenth aspect, X-ray imaging performed in advance is bidirectional scout imaging that obtains a bidirectional scout image obtained by imaging a subject from two directions. Therefore, the local imaging region can be accurately positioned in the three-dimensional space.

  The effects of the medical CT imaging method of the twentieth aspect are similar to the effects of the first aspect.

  The effects of the program of the twenty-first aspect are the same as the effects of the twentieth aspect, and version upgrade can be performed when the program itself is improved.

  The effects of the recording medium of the twenty-second aspect are the same as the effects of the twenty-first aspect, and the program of the twenty-first aspect can be transported.

It is a side view which shows the X-ray imaging apparatus 10 of embodiment. It is a perspective view which shows the imaging | photography part 20 seen from diagonally upward. It is a perspective view which shows the imaging | photography part 20 seen from diagonally downward. It is a schematic side view of the imaging unit 20 of the embodiment. It is a schematic plan view of the upper frame 64 of the embodiment. It is a schematic side view of the upper frame 64 of the embodiment. It is a schematic front view which shows the beam shape adjustment part 44 of embodiment. It is a schematic front view of the beam shape adjustment part 44 of embodiment. It is a schematic front view of the beam shape adjustment part 44 of embodiment. It is a top view which shows the X-ray irradiation path at the time of cephalo photography. It is a block diagram showing the composition of X-ray imaging system 10 of an embodiment. 6 is a diagram showing a data flow in the main body control unit 80. FIG. It is a figure for explaining a mode that a photography field ROI which is a CT photography object is set up on panoramic X-ray image PA1. It is a figure for explaining a mode that a photography field ROI which is a CT photography object is set up on a two-way scout image. It is a figure for explaining a mode that a photography field ROI is set up on illustration image I10. It is a figure which shows the control profile 830a corresponding to the imaging | photography area ROI set to the front tooth. It is a figure which shows the control profile 830b corresponding to the imaging | photography area ROI set to the right molar. It is a figure for demonstrating the example which produces | generates the transmission information 832 based on the panoramic X-ray image PA1. It is a figure which shows pixel value distribution VD1 which is a distribution of the pixel value in the horizontal range HR11 shown in FIG. It is a figure which shows the individual-specific control profile 834b produced | generated by adjusting the control profile 830b. It is a figure for explaining an example which generates transparency information 832 based on a two-way scout image. It is a figure for demonstrating the other example which produces | generates the transmission information 832 based on the panoramic X-ray image PA1. It is a figure which shows another example of the individual application adjustment. It is a figure which shows the individual control profile 834b (834b2) produced | generated during CT imaging. It is a figure which shows the panoramic X-ray image PA2 typically. It is a figure which shows typically the panoramic imaged image PA3 containing several metal prosthesis MP1. FIG. 27 is a schematic plan view showing how the X-ray cone beam BX1 is applied to the imaging region ROI shown in FIG. 26. It is a figure which shows the modification of the embodiment shown in FIG. It is a schematic front view which shows the detection surface 52S of the X-ray detector 52. It is a figure which shows individual-specific control profile 834L, 834M, 834S produced | generated according to physique information 836.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that the constituent elements described in this embodiment are merely examples, and the scope of the present invention is not intended to be limited thereto. In the drawings, for ease of understanding, the dimensions and number of each part may be exaggerated or simplified as necessary.

  Expressions indicating relative or absolute positional relationship (eg, “parallel”, “orthogonal”, “center”, “concentric”, “coaxial”, etc.) not only represent the positional relationship strictly, but also include tolerances or It also represents a state of being relatively displaced with respect to an angle or a distance within a range in which a similar function can be obtained.

<1. Embodiment>
FIG. 1 is a side view showing an X-ray imaging apparatus 10 of the embodiment. FIG. 2 is a perspective view showing the photographing unit 20 as seen from diagonally above. FIG. 3 is a perspective view showing the photographing unit 20 as viewed from diagonally below. FIG. 4 is a schematic side view of the image capturing unit 20 of the embodiment. In FIGS. 3 and 4, the cephalo unit 66 is omitted. FIG. 5 is a schematic plan view of the upper frame 64 of the embodiment. FIG. 6 is a schematic side view of the upper frame 64 of the embodiment.

  In each drawing, the X-axis, Y-axis, and Z-axis, which are right-handed orthogonal coordinate systems, and the x-axis, y-axis, and z-axis, which are right-handed orthogonal coordinate systems, are shown. Here, the X axis, the Y axis, the x axis, and the y axis are horizontal directions, and the Z axis and the z axis are vertical directions. In each axis, the direction in which the tip of the arrow points is the + (plus) direction, and the opposite direction is the- (minus) direction.

  The XYZ orthogonal coordinate system is a coordinate system defined on a fixed portion (for example, the column 70) of the X-ray imaging apparatus 10. With the head MH (subject) of the subject M1 introduced into the imaging unit 20 being held by the subject holding unit 72, the front of the head MH is + Y direction and the head MH is seen from the subject M1. The rear is the -Y direction, the right-hand direction is the + X direction, the left-hand direction is the -X direction, the upper direction is the + Z direction, and the lower direction is the -Z direction.

  The xyz orthogonal coordinate system is a coordinate system defined on the revolving arm 62 that rotates relative to a fixed portion such as the column 70 provided on the base 7B. When the X-ray generation unit 40 is viewed from the front toward the X-ray detection unit 50, the front direction is + y direction, the rear direction is -y direction, the right hand direction is + x direction, the left hand direction is -x direction, and the upper direction is. The + z direction and the downward direction are the -z direction. The z-axis direction is the vertical direction parallel to the Z-axis direction. The swivel arm 62 rotates about a rotation axis 65A parallel to the Z-axis direction and the z-axis direction. The rotation of the swivel arm 62 also rotates the xyz rectangular coordinate system around the z-axis direction.

  The X-ray imaging apparatus 10 includes an imaging unit 20 and an image processing device 30. The imaging unit 20 performs X-ray imaging of the subject M1 and collects X projection data. The imaging unit 20 may be used while being housed in the X-ray room 22. The image processing device 30 processes the X-ray projection data collected by the imaging unit 20 to generate various X-ray images including a panoramic image, a CT image and a cephalometric image.

<Photographing unit 20>
The imaging unit 20 includes an X-ray generation unit 40, an X-ray detection unit 50, a swivel arm 62 (supporting unit), a support unit 70, and a main body control unit 80. The configuration or function of each of these elements will be described below.

<X-ray generator 40>
As shown in FIG. 4, the X-ray generation unit 40 includes an X-ray generator 42 and a beam shape adjustment unit 44. The X-ray generator 42 and the beam shape adjusting unit 44 are housed in a housing 46. The housing 46 is supported by the turning arm 62.

  The X-ray generator 42 includes an X-ray tube that is an X-ray source that generates X-rays. The output intensity, which is the intensity of the X-ray beam emitted from the X-ray generator 42, is controlled by changing at least one of the voltage and the current supplied to the X-ray tube 42T (see FIG. 4). The control of the X-ray generator 42, that is, the control of at least one of the voltage amount and the current amount is performed according to a control command from the irradiation control unit 803 of the main body control unit 80.

  The beam shape adjustment unit 44 regulates the spread of the X-ray beam emitted from the X-ray generator 42, and adjusts the X-ray beam into a shape according to the imaging purpose. The beam shape adjustment unit 44 controls the X-ray irradiation range (irradiation region) for the subject M1. The beam shape adjustment unit 44 operates according to a control command from the irradiation control unit 803.

  FIG. 7 is a schematic front view showing the beam shape adjusting unit 44 of the embodiment. FIG. 8 is a schematic front view of the beam shape adjusting unit 44 of the embodiment. FIG. 9 is a schematic front view of the beam shape adjusting unit 44 of the embodiment. FIG. 7 shows the beam shape adjusting unit 44 at the time of CT imaging of the large irradiation field, FIG. 8 shows at the time of panoramic X-ray imaging, and FIG. 9 shows the beam shape adjusting unit 44 at the time of CT imaging of the small irradiation field.

  As shown in FIGS. 7 and 8, the beam shape adjusting unit 44 includes four shield members 441, 442, 443, 444 arranged at positions close to the X-ray generator 42. The shielding members 441-444 are made of a material that absorbs X-rays such as lead, and have a rectangular plate shape.

  The shielding members 441 and 442 are arranged at the upper side (+ z side) and the lower side (−z side) of the emission port of the X-ray generator 42, and their long sides are parallel to the x-axis direction. It is arranged to be. The beam shape adjusting unit 44 includes a moving mechanism (not shown) that moves each of the shielding members 441 and 442 in the vertical direction (z-axis direction). The moving mechanism may be, for example, a ball screw mechanism or a linear motor mechanism.

  The shielding members 443 and 444 are arranged at positions on the left side (+ x side) and the right side (−x side) of the emission port of the X-ray generator 42, and their long sides are parallel to the z-axis direction. Are arranged as follows. The beam shape adjusting unit 44 includes a moving mechanism (not shown) that moves each of the shielding members 443 and 444 in the lateral direction (x-axis direction). The moving mechanism may be a ball screw mechanism or a linear motor mechanism.

  The position of each of the shielding members 441-444 is controlled by each moving mechanism so that the opposing edge portions 441a and 442a of the shielding members 441 and 442 and the opposing edge portions 443a and 444a of the shielding members 443 and 444 can be controlled. The enclosed opening 445 has a shape and size according to the purpose of photographing.

  For example, as shown in FIG. 7, when the distance between the edge portions 441a and 442a and the distance between the edge portions 443a and 444a are adjusted relatively large, the opening 445 has a square shape in a front view. The X-ray beam emitted from the X-ray generator 42 is shaped into an X-ray cone beam that spreads toward the X-ray detection unit 50 in the shape of a regular pyramid by passing through the square opening 445. The X-ray cone beam is suitable for large field CT imaging.

  As shown in FIG. 8, when the distance between the edge portions 443a and 444a is relatively small and the distance between the edge portions 441a and 442a is adjusted to be large, the opening 445 becomes a vertically long rectangular shape in a front view. The X-ray beam emitted from the X-ray generator 42 passes through the rectangular opening 445 to be shaped into an X-ray slit beam that spreads in a vertically long truncated pyramid shape. The X-ray slit beam is suitable for panoramic radiography.

  The beam shape adjusting unit 44 may include shield members 446 and 447 shown in FIG. 9 instead of the shield members 441 to 444. The shielding members 446 and 447 are plate-shaped members formed in an L-shaped plate shape. The openings 448 are formed by combining the edge portions 446a and 447a that are the inner corner portions of the shielding members 446 and 447, respectively. Each of the shielding members 446 and 447 can be moved in the vertical direction (z-axis direction) and the horizontal direction (x-axis direction) by a moving mechanism (not shown). The shape of the opening 448 is adjusted by adjusting the positions of the shielding members 446 and 447 by this moving mechanism. As shown in the figure, the X-ray cone beam formed in a state where the opposite sides of each of the four sides of the opening 448 are not separated from each other as shown in FIG. 7 is suitable for small field CT imaging. Of course, the openings of the same width can be formed by the four shield members 441, 442, 443, 444 shown in FIGS. 7 and 8.

  The beam shape adjusting unit 44 shown in FIGS. 7 to 9 includes a plurality of shielding members 441-444 or shielding members 446 and 447, and a moving mechanism that moves these. However, the beam shape adjusting unit 44 can also be configured by a single shielding member having a plurality of openings formed according to the purpose of imaging, and a moving mechanism. In this case, the single shield member may be moved by the moving mechanism so that the X-ray beam emitted from the X-ray generator 42 passes through the opening corresponding to the imaging purpose according to the imaging purpose.

<X-ray detector 50>
As shown in FIG. 4, the X-ray detector 50 includes an X-ray detector 52. The X-ray detector 52 detects the X-ray beam emitted from the X-ray generator 40. The X-ray detector 52 may be configured by a flat panel detector (FPD) having a detection surface extending on a plane, an X-ray fluorescence intensifier (II: Image Intensifier), or the like.

  The plurality of detection elements arranged on the detection surface of the X-ray detector 52 convert the intensity of the incident X-ray into an electric signal. Then, the electric signal is input to the main body control unit 80 or the image processing device 30 as an output signal. The main body control unit 80 or the image processing device 30 generates an X-ray projection image based on the signal.

  The X-ray detector 52 is provided on the side surface facing the X-ray generator 42 inside the housing 54. The X-ray beam emitted from the X-ray generator 42 is applied to the detection surface of the X-ray detector 52. The housing 54 is supported by the swivel arm 62 in a state where the X-ray detector 52 is housed.

<Swivel arm 62>
The revolving arm 62 is suspended from and supported by the upper frame 64 via the rotating shaft 65. The casing 46 is attached to one end of the revolving arm 62, and the casing 54 is attached to the other end of the revolving arm 62. That is, the revolving arm 62 supports the X-ray generator 42 on one end side via the housing 46 and supports the X-ray detector 52 on the other end side via the housing 54.

  The insides of the housings 46, 54 and the pivot arm 62 form a series of cavities. Wirings (signal wirings, power supply wirings, control wirings, etc.) for operating the respective elements of the X-ray generation unit 40 and the X-ray detection unit 50 are arranged in this cavity. At appropriate positions of the casings 46, 54 and the swivel arm 62, an opening for work for attaching wiring or a control board, an opening for radiating heat, and the like may be provided.

  As shown in FIGS. 1 to 4, the upper frame 64 is attached to the column 70. A rotary shaft 65 extending in the Z-axis direction is attached to an intermediate portion of the upper frame 64, and an end portion of the rotary shaft 65 supports the X-ray generation unit 40 and the X-ray detection unit 50 in the swivel arm 62. It is connected to the intermediate position between the parts to be. Therefore, the revolving arm 62 is supported by the upper frame 64 in a suspended state via the rotating shaft 65.

  As shown in FIG. 6, a turning drive unit 642 is provided inside the turning arm 62. The turning drive unit 642 rotates the turning motor 6421 provided inside the turning arm 62 to turn the turning arm 62 about the rotation shaft 65. As shown in FIG. 6, the turning drive unit 642 includes a turning motor 6421 and an endless belt 6422. The turning drive unit 642 (specifically, the turning motor 6421) is controlled by the support body control unit 802. The endless belt 6422 is stretched around the turning motor 6421 and the rotating shaft 65. The endless belt 6422 is rotated by the drive of the turning motor 6421, so that the turning arm 62 is rotated.

  A bearing 6423 (see FIG. 6) is interposed between the rotary shaft 65 and the swing arm 62. The bearing 6423 allows the revolving arm 62 to rotate smoothly with respect to the rotating shaft 65.

  The turning drive unit 642 may be provided inside the upper frame 64. In this case, the rotation shaft 65, which is rotatable with respect to the upper frame 64, is rotated together with the revolving arm 62 fixed to the rotation shaft 65.

  Inside the rotary shaft 65, a rotary axis 65A is set which is a shaft around which the rotary arm 62 mechanically swivels. As shown in FIG. 4, the revolving arm 62, the housing 46, and the housing 54 form a revolving unit 67. The upper frame 64 is a swivel support portion 64A that supports the swivel portion 67 via the rotary shaft 65. When the revolving arm 62 revolves around the axis of the rotation shaft 65, the revolving unit 67 revolves around the rotation axis 65A.

  The revolving arm 62 supports the housing 46 at one end side, and supports the housing 54 at the other end side opposite thereto. As a result, the revolving arm 62 supports the X-ray generator 42 at a part sandwiching the rotation axis 65A, and supports the X-ray detector 52 at another part. That is, the support section rotatably supports the subject M1 while sandwiching the subject M1 in a state where the X-ray generator 42 and the X-ray detector 52 face each other.

  Inside the upper frame 64, a horizontal drive unit 644 that moves the rotating shaft 65 in the X-axis direction and the Y-axis direction is provided. The horizontal drive unit 644 moves the rotating shaft 65 in the X-axis direction and the Y-axis direction, thereby moving the revolving arm 62 in the X-axis direction and the Y-axis direction. The horizontal drive unit 644 includes an XY table 6440 and a drive motor 6442 shown in FIG.

  The XY table 6440 includes an X table 6440X and a Y table 6440Y. The X table 6440X moves the revolving arm 62 in the lateral direction (X axis direction). The Y table 6440Y moves the turning arm 62 in the front-rear direction (Y-axis direction). The X table 6440X is fixed to the Y table 6440Y, and moves in the Y axis direction as the Y table 6440Y moves in the Y axis direction. The drive motor 6442 includes an X-axis drive motor 6442X that drives the X table 6440X and a Y-axis drive motor 6442Y that drives the Y table 6440Y.

  In the X-ray imaging apparatus 10, the horizontal drive unit 644 operates according to a control command from the support body control unit 802 of the main body control unit 80. The horizontal drive unit 644 moves the rotary shaft 65 together with the turning drive unit 642 in the X-axis direction and the Y-axis direction. The rotating shaft 65 is movable in the XY plane and rotates about the Z axis which is the axial center position of the rotating shaft 65 at the position after the movement in the XY plane.

  The horizontal drive unit 644 may be provided inside the swing arm 62. In this case, the other end of the rotary shaft 65 fixed at a fixed position in the XY plane of the upper frame 64 is fixed to the XY table 6440 provided in the turning arm 62. Then, as the XY table 6440 moves in the X-axis direction and the Y-axis direction, the revolving arm 62 moves in the X-axis direction and the Y-axis direction with respect to the rotary shaft 65 that is at a fixed position.

  Both the swing drive unit 642 and the horizontal drive unit 644 may be provided inside the swing arm 62. In this case, the revolving arm 62 moves in the X-axis direction and the Y-axis direction relative to the rotation shaft 65 that is fixed at a fixed position in the XY plane and does not rotate, and rotates relatively.

  As shown in FIG. 4, a vertical drive unit 646 (vertical movement drive unit) is attached to the column 70. The vertical drive unit 646 moves the upper frame 64 up and down in the Z-axis direction. The vertical drive unit 646 includes a motor 6462, a ball screw 6464, a nut unit 6466, and a plurality of (here, four) roller units 6468.

  The motor 6462 rotates a ball screw 6464 extending in the Z-axis direction around the Z-axis. The nut portion 6466 is screwed onto the ball screw 6464. Each of the roller portions 6468 engages with a pair of rail portions 702 provided on the support column 70 so as to be movable up and down, and a moving direction such that the roller portions 6468 move only in the extending direction (Z-axis direction) of the pair of rail portions 702. Is regulated.

  In the example shown in FIG. 4, a motor 6462 arranged on the base 7B is attached to the lower portion of the column 70, and a nut portion 6466 is fixed to the upper frame 64. Each roller portion 6468 is attached to the upper frame 64.

  When the motor 6462 rotates the ball screw 6464 clockwise or counterclockwise, the nut portion 6466 moves upward or downward along the ball screw 6464. Each of the roller portions 6468 moves on the pair of rail portions 702, so that the upper frame 64 moves up and down in the Z-axis direction. As the upper frame 64 moves up and down, the X-ray generation unit 40 and the X-ray detection unit 50 supported by the turning arm 62 move in the Z-axis direction. The vertical drive unit 646 is an example of a vertical movement drive unit that vertically moves the upper frame 64 to vertically move the revolving arm 62 and the upper frame 64.

<Cephalo unit 66>
The cephalo unit 66 is a unit used to obtain a head X-ray standard photograph. As shown in FIGS. 1 and 2, the cephalo unit 66 is provided at the tip of an arm 648 that extends horizontally from the upper frame 64. The cephalo unit 66 includes a head fixture 660, a secondary slit mechanism 662, and an X-ray detector 664.

  The head fixing device 660 is a device for positioning the head MH, and here, a pair of rod-shaped tips are inserted into the ears on both sides of the head MH to position the ears, and , A forehead rod that contacts the forehead of the head MH and positions the head. Here, the head MH is positioned by the head fixture 660 such that the front thereof faces the + X side.

  The secondary slit mechanism 662 includes a slit member having a slit extending in the Z-axis direction and a moving mechanism that moves the slit member in the Y direction. Of the X-rays emitted from the X-ray generator 42, the X-rays that have passed through the slits are applied to the head MH fixed to the head fixture 660. In the Cephalography, the head MH is scanned with X-rays by moving the slit member in the X-axis direction.

  The X-ray detector 664 detects X-rays transmitted through the head MH positioned by the head fixture 660. The X-ray detector 664 includes an X-ray detector that detects X-rays, and a moving mechanism that moves the X-ray detector in the Y-axis direction. The X-ray detector has a detection surface corresponding to the shape of the slit of the secondary slit mechanism 662 and extending in the + Z direction. The moving mechanism moves the X-ray detector in the Y-axis direction in accordance with the movement of the slit member in the Y-axis direction. As a result, the X-ray detector detects the X-rays that have passed through the slit and transmitted through the head MH.

  FIG. 10 is a plan view showing the X-ray irradiation path at the time of cephalography. When the Cephalography is performed in the X-ray imaging apparatus 10, as shown in FIG. 10, the revolving arm 62 rotates by a predetermined angle, and the casing 46 releases the facing relationship with the X-ray detection unit 50 to perform the Cephalography. Rotate so as to face the X-ray detector 664 for use. As a result, the X-ray detection unit 50 is arranged at a position deviating from the line connecting the Cephalo unit 66 from the X-ray generation unit 40. The housing 46 of the X-ray generator 40 rotates about the Z-axis with respect to the swivel arm 62, so that the X-ray emission port of the X-ray generator 42 (the opening 445 of the beam shape adjustment unit 44) is opened. It is directed to the X-ray detector 664 of the cephalo unit 66. The mechanism for rotating the housing 46 may be manually operable or may be operated by the control of the main body controller 80. With the X-ray generation unit 40 and the cephalometer unit 66 arranged in the positional relationship shown in FIG. 10, the X-ray beam is emitted from the X-ray generation unit 40 to perform the cephalograph.

<Post 70>
The support column 70 is a long member extending in the Z-axis direction and supports the upper frame 64 and the subject holding unit 72.

<Subject holding unit 72>
The subject holding unit 72. holds the head MH of the subject M1. The subject holding unit 72 includes a chin rest 722, a head holder 723, a lower frame 724, an arm unit 726, and a holding unit driving unit 728.

  The chin rest 722 holds the head MH by supporting the tip of the lower jaw of the head MH. The head holder 723 positions the head MH in the X-axis direction by sandwiching the head MH from both sides. The chin rest 722 and the head holder 723 are connected to the lower frame 724 via the arm portion 726. The mechanical element configured by the chin rest 722, the head holder 723, and the like, which fixes the head MH of the subject M1 constitutes the subject holding section 72 or a part thereof as the head holding section 72H.

  The lower frame 724 is attached to the support column 70 and moves in the Z-axis direction. When the lower frame 724 moves in the Z-axis direction, the chin rest 722 fixed to the arm portion 726 moves in the Z-axis direction.

  The arm portion 726 is a member that connects the chin rest 722 to the lower frame 724. In the example shown in FIG. 4, the arm portion 726 includes a portion that extends from the lower frame 724 in parallel with the XY plane and a portion that extends in the Z axis and is connected to the chin rest 722.

  The holding unit drive unit 728 includes a motor 7228, a ball screw 7284, a nut unit 7286, and a plurality of (here, four) roller units 7288.

  The motor 7382 rotates a ball screw 7284 extending in the Z-axis direction around the Z-axis. The nut portion 7286 is screwed into the ball screw 7284. Each of the roller portions 7288 is engaged with the pair of rail portions 702. As a result, the moving direction of each roller portion 7288 is regulated so that each roller portion 7288 moves only in the extending direction (Z-axis direction) of the pair of rail portions 702.

  In the example shown in FIG. 4, the motor 7228 and the ball screw 7284 are fixed to the lower frame 724. The nut portion 7286 is fixed to the upper frame 64. In the illustrated example, the ball screw 7284 extends in the + Z direction from the top portion of the lower frame 724 and is screwed with the nut portion 7286 fixed near the bottom portion of the upper frame 64. Each of the roller portions 7288 is attached to the lower frame 724.

  The motor 7382 rotates the ball screw 7284 clockwise or counterclockwise, whereby the lower frame 724 moves in the vertical direction with respect to the nut portion 7286 fixed to the upper frame 64. At this time, each of the roller portions 7288 moves along the pair of rail portions 702, so that the lower frame 724 moves in the Z-axis direction.

  By moving the lower frame 724 in the Z-axis direction, the chin rest 722 moves in parallel with the Z-axis. While the height of the head MH is maintained at a constant position, the turning arm 62 is moved up and down relative to the head MH, whereby the irradiation position of the X-rays on the head MH is changed in the Z-axis direction. . Specifically, the turning arm 62 and the subject holding unit 72 are moved up and down by the vertical drive unit 646 in accordance with the actual position of the head MH, and the head MH is fixed to the head holding unit 72H. After that, the vertical drive unit 646 raises the turning arm 62, and the holding unit drive unit 728 lowers the subject holding unit 72 with the same displacement amount. As a result, the position of the revolving arm 62 with respect to the head can be raised while keeping the height of the head MH constant. Alternatively, the vertical drive unit 646 lowers the turning arm 62, and the holding unit drive unit 728 raises the subject holding unit 72 with the same displacement amount. Thereby, the position of the revolving arm 62 with respect to the head can be lowered while keeping the height of the head MH constant.

  The turning arm 62 and the subject holding unit 72 (head holding unit 72H) are vertically moved integrally by the vertical drive unit 646. The subject holding unit 72 is moved up and down relatively by the holding unit driving unit 728 with respect to the turning arm 62. That is, the turning arm 62 and the subject holding unit 72 can be moved up and down independently by the vertical driving unit 646 and the holding unit driving unit 728.

  The position at which the head MH of the subject M1 is supported may be changed by changing the positions of the chin rest 722 and the head holder 723 in the Z-axis direction. For example, the positions of the chin rest 722 and the head holder 723 are set according to the position of the head MH of the subject M1 in the upright posture. As shown in FIG. 4, when the subject M1 has a standard skeleton and the head MH is held by the subject holding unit 72, the Frankfurt plane FR1 of the subject M1 becomes horizontal. When the head MH is held by the subject holding unit 72, the body axis BA1 passing through the head MH becomes parallel to the vertical direction. The “body axis” refers to a symmetry axis that is set when the human body is viewed from the front and the human body is considered to be generally symmetrical.

<Main body control unit 80>
FIG. 3 is a block diagram showing the configuration of the X-ray imaging apparatus 10 of the embodiment. FIG. 12 is a diagram showing a data flow in the main body control unit 80. The main body control unit 80 controls each element of the imaging unit 20 to cause the imaging unit 20 to perform X-ray imaging. The hardware configuration of the main body control unit 80 is similar to that of a general computer or workstation. That is, the main body control unit 80 includes a CPU that performs various arithmetic processes, a ROM that is a read-only memory that stores a basic program, a RAM that is a readable and writable memory that stores various information, and a control application or data. A storage unit for storing is provided.

  An operation display unit 82 is connected to the main body control unit 80. The operation display unit 82 is provided to display various information. The operation display unit 82 includes an operation display panel including a touch panel display. The operation display unit 82 is provided for displaying various information as an image and allowing an operator to input various information (including shooting conditions) to the main body control unit 80. As shown in FIG. 1, the operation display unit 82 is provided on the outer wall surface of the X-ray protection room 22. The operation display unit 82 may be provided on a part of the imaging unit 20, for example, on the outer surface of the housing 54.

  As shown in FIG. 11, the main body control unit 80 includes a mode setting unit 800, a region setting unit 801, a support body control unit 802, an irradiation control unit 803, a holding unit control unit 804, a profile selection unit 805, and a transmission information generation unit 806. And a profile changing unit 807. Each of these processing units is a function realized by the CPU operating in accordance with a control application (program). The CPU may be a general purpose circuit. Instead of using the CPU as a whole, some or all of these functions may be realized by hardware by a dedicated circuit or the like. Of the circuits of the CPU, the portions used for various controls by various control applications may be regarded as the processing units 800-807, respectively, and the integrated circuit may be regarded as the main body control unit 80. The processing units 800-807 may be regarded as circuits to which signals of various control applications are applied. Needless to say, when the CPU accepts an input or the like, specifically, a signal such as an input is accepted. For example, the operation of the operator on the operation display unit 82 is converted into an input signal and applied to the circuit of the CPU. Further, when the CPU performs selection or the like, in detail, the circuit outputs a selection signal. In addition, area setting and the like are performed by coordinate calculation and the like. The control application is recorded in a computer-readable non-transitory recording medium such as an optical medium (CD, DVD, etc.), a magnetic medium, a flash memory, or the like.

  The mode setting unit 800 sets an imaging type (mode) of the X-ray imaging apparatus 10. The X-ray imaging apparatus 10 performs various types of imaging according to the imaging mode set by the mode setting unit 800. In the X-ray imaging apparatus 10, modes corresponding to panoramic X-ray imaging, CT imaging, and cephalo imaging are defined in advance. In the X-ray imaging apparatus 10, the mode selection is accepted via the operation display unit 82, and the mode setting unit 800 sets the imaging mode according to the selection content. In this embodiment, the mode setting unit 800 and the operation display unit 82 configure a mode setting receiving unit that receives selection of one shooting mode from a plurality of shooting modes.

  The area setting unit 801 sets an imaging area (imaging target range) according to a mode executed in the X-ray imaging apparatus 10. The area setting unit 801 displays on the operation display unit 82 an area setting screen suitable for the shooting mode set by the mode setting unit 800. Then, the area setting unit 801 sets the shooting area based on the operation input performed by the operator on the operation display unit 82. The area setting unit 801 and the operation display unit 82 configure an area setting receiving unit 820 for designating a shooting area.

  The area setting reception unit 820 receives an operation input for specifying a local imaging area from the operator when performing CT imaging in the imaging unit 20. The local imaging region is a partial region of the head MH of the subject M1 who is the subject arranged between the X-ray generator 42 and the X-ray detector 52. Although the local imaging region is a partial region of the head MH, when it is a region where the entire dental arch fits in a plan view (local region of the entire dental arch), the entire jaw including the dental arch and the temporomandibular joint is It can be considered as a region that fits (local region of the entire jaw), a partial region of the dental arch (local region of the dental arch), or a partial region of the jaw (local region of the jaw part). In addition, it is also possible to consider the upper jaw region, the lower jaw region, and the upper and lower jaw regions in a lateral view.

  A plurality of sizes of the local imaging area can be prepared in advance. For example, diameter 40 mm / height 40 mm, diameter 40 mm / height 80 mm, diameter 80 mm / height 40 mm, diameter 80 mm / height 50 mm, diameter 80 mm / height 80 mm, diameter 100 mm / height 50 mm, diameter 100 mm / height 80 mm It is good to prepare such as. The diameter of 40 mm is suitable for the local area of the dental arch or the partial area of the jaw, the diameter of 80 mm is suitable for the local area of the entire dental arch, and the diameter of 100 mm is suitable for the local area of the entire jaw. The height of 40 mm or 50 mm is suitable for the upper jaw region or the lower jaw region, and the height of 80 mm is suitable for the upper and lower jaw regions. A screen capable of selecting the size of each imaging region can be displayed on the operation display unit 82, and an operation input as to which size of the local imaging region is selected can be accepted. The area setting unit 801 specifies and sets a shooting area based on an operation input performed by the operator on the operation display unit 82. In this case, the area setting reception unit 820 has the function of the area size setting reception unit.

  In the present embodiment, the local region of the dental arch or the local region of the jaw is mainly described as the local region, but the control profile 830 may be prepared for the local region of the entire arch and the local region of the jaw.

  FIG. 13 is a diagram for explaining how to set an imaging region ROI that is a CT imaging target on the panoramic X-ray image PA1. In this example, the region setting unit 801 displays the panoramic X-ray image PA1 in the display region of the operation display unit 82, and also displays the frame cursor BC1 for designating the imaging region ROI. Regarding the display of the frame cursor BC1, the range surrounded by the frame is displayed so as to match the range of the photographing region ROI. The vertical line and the horizontal line displayed in the frame cursor BC1 are arranged such that their intersection points indicate the center of the photographing region ROI. The rectangular frame may be omitted and only the vertical and horizontal lines may be used as the cursor.

  As the panoramic image PA1, an image obtained by panoramic X-ray imaging in the main imaging section 20 can be used. In this case, since the spatial positional relationship between the subject holding unit 72 and the frame cursor is clear, the coordinates can be calculated. Further, the irradiation conditions such as the tube current and the tube voltage when the panoramic image PA1 is acquired can be referred to. The position of the panoramic tomographic image formed by the panoramic image PA1 is determined with respect to the subject holding unit 72. Therefore, the three-dimensional position near the head MH holding unit of the subject holding unit 72 can be specified by specifying the position on the panoramic image PA1. If there is position information and irradiation condition information at the time of acquisition of the panoramic image PA1, an image taken by another X-ray imaging device can also be used. This also applies to the two-direction scout image described later.

  The frame cursor BC1 can be moved in an arbitrary direction within a two-dimensional plane consisting of a horizontal direction and a vertical direction on the panoramic X-ray image PA1 by the operator operating the operation display unit 82. The frame cursor BC1 can be moved by, for example, operating the mouse to hold the frame cursor BC1 by the pointer and moving the cursor to release it at a desired position. The operator moves the frame cursor BC1 to a position where CT imaging is desired, and performs a predetermined determination operation. Then, the region setting unit 801 obtains a region of the XYZ coordinate system corresponding to the region surrounded by the frame cursor BC1 at the time of this determination operation by coordinate conversion or the like, and sets the region as the photographing region ROI.

  FIG. 14 is a diagram for explaining how to set an imaging region ROI that is a CT imaging target on a two-way scout image. In this example, the area setting unit 801 displays a two-way scout image in the display area of the operation display unit 82. The two-direction scout image is obtained by X-ray irradiation from the X-ray generator 42 to the X-ray detector 52 from the side (here, the left side) of the head MH of the subject M1 held by the subject holding unit 72. A side projection image PI1 obtained by simple projection and a front projection image PI2 obtained by simply projecting the head MH from the front by changing the turning angle of the turning arm 62 are included. X-ray imaging for obtaining such a bidirectional scout image is also referred to as bidirectional scout imaging. In the two-direction scout photographing, the head MH may be photographed at different angles of 90 degrees such as the side and the front, but may be photographed at other different angles. However, when the shooting direction is an angle of 180 °, such as the front and the rear or the left and the right, it is desirable to avoid the component in the intersecting direction because the three-dimensional position cannot be specified. In this example, the area setting unit 801 displays a frame cursor BC2 on the side projection image PI1 and a frame cursor BC3 on the front projection image PI2. With respect to the display of the frame cursors BC2 and BC3, the range surrounded by the frames is displayed so as to match the range of the photographing region ROI. Instead of the two-direction scout image, a front cephalo photographed image and a side cephalo photographed image photographed by the cephalo unit 66 may be used.

  The operator can move the frame cursors BC2 and BC3 on each image as in the case of the frame cursor BC1. When the operator performs a predetermined determination operation, the area setting unit 801 obtains an area in the XYZ coordinate system corresponding to the area surrounded by the frame cursors BC2 and BC3, and sets the area as the imaging area ROI.

  The horizontal position of the frame cursor BC2 in the side projection image PI1 indicates the position in the front-back direction (Y-axis direction) of the imaging region ROI. The horizontal position of the frame cursor BC3 in the front projection image PI2 indicates the position in the left-right direction (X-axis direction) of the imaging region ROI. The vertical positions of the frame cursors BC2 and BC3 in the images PI1 and PI2 indicate the vertical position (Z-axis direction) of the photographing region ROI. The frame cursors BC2 and BC3 move in the vertical direction in conjunction with each other in each of the images PI1 and PI2. Preferably, a line cursor VC1 extending in the vertical direction and a line cursor HC1 extending in the horizontal direction are displayed on the side projection image PI1, and a line cursor VC2 extending in the vertical direction and the line cursor VC2 extending in the horizontal direction are displayed on the front projection image PI2. A line cursor HC2 that extends to is displayed.

  As shown in FIG. 14, the crossing position of the two line cursors VC1 and HC1 is displayed so as to be the center of the frame cursor BC2, that is, the center of the photographing region ROI in the side view, and the crossing position of the line cursors VC2 and HC2 is displayed. It is displayed so as to be the center of BC3, that is, the center of the imaging region ROI in the forward-looking or backward-viewing. The line cursors VC1 and VC2 can be moved horizontally on each image, and the line cursors HC1 and HC2 can be moved vertically on each image.

  The horizontal position of the line cursor VC1 in the side projection image PI1 indicates the position in the front-rear direction (Y-axis direction) of the center of the imaging region ROI. The horizontal position of the line cursor VC2 in the front projection image PI2 indicates the position in the left-right direction (X-axis direction) of the center of the imaging region ROI. Further, the vertical positions of the line cursors HC1 and HC2 in the images PI1 and PI2 indicate the vertical position (Z-axis direction) of the center of the imaging region ROI.

  Preferably, the frame cursor BC2 and the line cursors VC1 and HC1 are displayed so as to interlock with each other. That is, when the frame cursor BC2 is moved, the line cursors VC1 and HC1 move without adding the move operation, and when the line cursors VC1 and HC1 are moved, the frame cursor BC2 moves without adding the move operation. The frame cursor BC3 and the line cursors VC2 and HC2 may be displayed so as to be interlocked with each other.

  Preferably, the line cursors HC1 and HC2 are also linked. That is, when either one of the line cursors HC1 and HC2 moves, the other line cursor moves so as to indicate the same vertical position (height) on the subject without performing a moving operation.

  13 and 14 are for setting the imaging region ROI of CT imaging by using the panoramic X-ray image PA1, the side projection image PI1, and the front projection image PI2 generated based on the past X-ray imaging. is there. However, instead of using the X-ray image, an illustration image simulating these X-ray images or an illustration image simulating an anatomy such as the upper jaw or the lower jaw is used so that the designation of the imaging region ROI can be accepted. Good.

  FIG. 15 is a diagram for explaining how to set the photographing region ROI on the illustration image I10. The illustration image I10 is an image imitating a plan view of the entire jaw. The same jaw view may be commonly used for the upper and lower jaws, or the lower jaw view and the upper jaw view may be switched and displayed for each target region. The lower jaw diagram may represent both the lower and upper jaws, and the upper jaw diagram may represent both the lower and upper jaws. The area setting unit 801 displays the illustration image I10 on the operation display panel of the operation display unit 82, and also displays the closed-loop frame cursor BC4. The operation display unit 82 receives an operation of enclosing a tooth, a temporomandibular joint, or the like of interest with the frame cursor BC4. The area setting unit 801 sets the area surrounded by the frame cursor BC4 as the imaging area ROI for CT imaging.

  The frame cursor BC4 is displayed in a circle on the illustration image I10, but the photographing region ROI in the real space is a substantially columnar shape extending in the Z-axis direction. The size (diameter) of the frame cursor BC4 may be changed to an arbitrary size by the operator performing a predetermined operation, or may be changed to a predetermined size. When the size of the frame cursor BC4 with respect to the drawing of the jaw is relatively changed, the size of the imaging region ROI may be changed. As the size of the imaging region ROI is changed, the X-ray shielding amount by the beam shape adjusting unit 44 is changed.

  The shape of the photographing area ROI in plan view (the shape when the photographing area ROI is looked down from the + Z side in the −Z direction) is not limited to a circle. For example, as described in Japanese Patent Application Laid-Open No. 2013-135765, by controlling the beam shape adjusting unit 44 during CT imaging, it is possible to change to various shapes such as an elliptical shape, an oval shape, and a substantially triangular shape. Good. In this case, it is preferable that the shape of the frame cursor BC4 can be changed according to the shape of the photographing region ROI.

  The support body control unit 802 controls the turning of the turning arm 62 by controlling the turning drive unit 642. Specifically, the support body control unit 802 rotates the X-ray generator 42 supported by the swivel arm 62 around the rotation axis 65, so that the X-ray beam for the subject M1 (X-ray cone beam BX1). Change the irradiation angle (projection angle) of. The rotary drive of the swivel arm 62 is the rotary drive of the X-ray detector 52 supported by the support. Further, the rotation drive of the turning arm 62 changes the light receiving angle of the X-ray cone beam BX1 with respect to the subject M1.

  In addition, the support body control unit 802 controls the horizontal drive unit 644 to control the movement of the revolving arm 62 in the X-axis direction and the Y-axis direction. Thereby, the support body control unit 802 moves the X-ray generator 42 and the X-ray detector 52 in the X-axis direction and the Y-axis direction.

  Further, the support body control unit 802 controls the vertical drive unit 646 to move the revolving arm 62 in the Z direction.

  The irradiation control unit 803 controls the X-ray generator 42, for example. Specifically, by controlling at least one of a current and a voltage supplied to the X-ray tube of the X-ray generator 42, the X-ray beam emitted from the X-ray generator 42 is turned on / off and the X-ray beam is emitted. Control the intensity of. Further, the irradiation control unit 803 controls the X-ray beam shielding by controlling the beam shape adjusting unit 44. By the shielding control of the X-ray beam, an X-ray beam (for example, an X-ray slit beam, an X-ray cone beam, etc.) having a shape according to the purpose of imaging is formed. Further, the irradiation control unit 803 controls the beam shape adjusting unit 44 to suppress the irradiation of the X-ray beam on the region other than the imaging region ROI of the subject M1.

  The holding unit control unit 804 moves the head holding unit 72H in the vertical Z-axis direction by giving a control command to the holding unit driving unit 728.

  The profile selection unit 805 selects one control profile 830 corresponding to the local imaging region set by the region setting unit 801 from the plurality of control profiles 830 stored in the storage unit 83. The control profile 830 is information for controlling the irradiation amount (hereinafter, also simply referred to as “X-ray irradiation amount”) per unit time that is irradiated to the subject M1 to be CT imaged. Here, a plurality of control profiles 830 corresponding to different local imaging regions (imaging regions ROI) are prepared in advance. The control profile 830 is prepared for each size of the local imaging area and can be selected.

  FIG. 16 is a diagram showing a control profile 830a corresponding to the imaging region ROI set for the front teeth. In FIG. 16, CT imaging is performed by rotating the X-ray generator 42 and the X-ray detector 52 on the upper side with the anterior teeth (central incisor and lateral incisor) of the jaw J1 of the head MH as the imaging region ROI. The situation is illustrated. Further, a graph in which the horizontal axis represents the swing angle of the swing arm 62 and the vertical axis represents the X-ray irradiation amount is shown on the lower side. In the present embodiment, the jaw J1 including the temporomandibular joint is targeted for imaging. However, in dentistry, since the main region of the jaw is the dental arch region, only the dental arch may be the jaw J1. .

  In CT imaging, the X-ray generator 42 and the X-ray detector 52 are rotated by 180 ° (or 180 ° plus the fan angle of the X-ray cone beam BX1). The X-ray detector 52 moves around the head on the side where the dental arch in the head is located. As shown in the drawing, when the imaging region ROI is in the front tooth region, the X-ray detector 52 is moved from the side of the head MH to the front side and to the opposite side. When CT imaging is performed by rotating the X-ray detector 52 by 180 ° or 180 ° plus the fan angle of the X-ray cone beam BX1, the X-ray detector 52 is located on the side of the head where the dental arch is present. The orbit that moves around the head has the advantage that the X-ray detector 52 can be brought close to the imaging region ROI. Of course, in CT imaging, the angle at which the X-ray generator 42 and the X-ray detector 52 are rotated is an arbitrary angle of 180 ° or more. For example, CT imaging may be performed by rotating 360 °.

  When CT imaging of the jaw of the subject M1 is performed, as shown in FIG. 16, there is a timing (turning angle) at which the X-ray cone beam BX1 passing through the imaging region ROI is also incident on the cervical spine HA1. The cervical vertebra HA1 is an X-ray high absorption region existing inside the subject M1 and having a relatively large X-ray absorption rate. When an X-ray high absorption region exists on the path of the X-ray cone beam BX1, the X-ray transmittance decreases, and therefore the X-ray transmission (or X-ray absorption) included in the X-ray projection image of the imaging region ROI is related. The amount of information decreases. As a result, the image quality (resolution or the like) of the CT image reconstructed from the X-ray projection image may deteriorate. Therefore, it is advisable to prepare in advance a control profile 830 for increasing the dose of X-rays to the subject M1 at the timing when the X-ray cone beam BX1 overlaps the cervical vertebra HA1.

  As shown in FIG. 16, when the front teeth of the jaw J1 are set in the imaging region ROI, when the X-ray detector 52 is in front of the head MH (that is, when the turning angle is 90 °), X The center of the imaging region ROI and the center of the cervical vertebra HA1 are aligned on the central axis of the line cone beam BX1. For this reason, the control profile 830a is set so that the X-ray irradiation amount increases near the turning angle of 90 °. In the control profile 830a for the front tooth, when the horizontal axis is the turning angle and the vertical axis is the X-ray irradiation amount, the graph showing the change in the X-ray irradiation amount of the X-ray shows a symmetrical shape around the turning angle 90 °. Has become.

  FIG. 17 is a diagram showing a control profile 830b corresponding to the imaging region ROI set for the right molar. When the imaging region ROI is set on the right molar, when the X-ray detector 52 passes the right side of the head MH (here, when the turning angle is about 90 ° to about 150 °), the X-ray cone The beam BX1 overlaps the cervical vertebra HA1. Therefore, the control profile 830b is set such that the projection angle is biased toward 180 ° rather than 90 °, and the X-ray irradiation amount is increased.

  As described above, the control profiles 830a and 830b define the X-ray irradiation dose according to the preset positional relationship between the imaging region ROI and the X-ray high absorption region (for example, the cervical vertebra HA1).

  A preset control profile such as the control profiles 830a and 830b may be referred to as a default control profile. The default control profile is, for example, a control profile that is adapted to a large number of device-ready subjects, applied to subjects with standard physical characteristics. A subject having a standard physical characteristic or a standard subject may be defined for each set, such as different age groups such as adult and child described later. Physical characteristics include physique, skeleton, distribution of hard tissue, and the like. Each set may be established with regard to physique, skeleton, distribution of hard tissue, and the like. For example, the physique may include large, medium, and small sets, and the jaw shape may include normal and frontal collision sets.

  The control profile 830 may be prepared in a one-to-one table for each designated position of the imaging region ROI, but may be calculated from the direction of the imaging region ROI with respect to the cervical spine. In this case, in the graphs of FIGS. 16 and 17, the portion of the profile where the X-ray irradiation dose is large is tentatively called an irradiation dose peak, and one curve pattern having this irradiation dose peak is prepared. . As shown in FIG. 16, when the anterior tooth region is the imaging region ROI, the timing at which the cervical spine reaches the X-ray path during the turning of the turning arm 62 in CT imaging comes to the center between the start and end. The dose peak of should be centered between the start and end. When the right molar region is the imaging region ROI as shown in FIG. 17, the timing when the cervical vertebrae reaches the X-ray path during the rotation of the clockwise rotation arm 62 in the plan view in CT imaging is the latter half between the start and the end. Since it comes closer to the curve, the dose peak of the curve pattern is positioned closer to the second half between the start and the end. In this way, the calculation for determining the position of the dose peak may be performed according to the direction in which the designated imaging region ROI is located with respect to the cervical vertebra HA1.

  The default control profile may be rewritable. As medical technology evolves, such as advances in the collection and analysis of clinical data, new default control profiles may emerge that may be more appropriate. The default control profile is rewritable or changeable so as to adapt to its appearance. Specifically, the control profile 830 stored in the storage unit 83 can be rewritten and changed. For rewriting or changing, for example, a wired or wireless port is provided, and an external storage medium storing a new control profile is connected, or a communication infrastructure such as WEB that communicates with a supplier providing the new control profile is used. It can be updated through connections etc.

  The change of the X-ray irradiation dose for the subject M1 may be performed by changing the intensity (dose) of the X-ray output from the X-ray generator 42. In this case, the irradiation control unit 803 may change the tube current or the tube voltage applied to the X-ray tube 42T according to the control profile 830.

  Further, the change of the X-ray irradiation amount for the subject M1 may be performed by changing the rotation speed of the X-ray cone beam BX1 (that is, the turning speed of the turning arm 62). When the rotation speed is decreased, the X-ray irradiation amount can be relatively increased, and when the rotation speed is increased, the X-ray irradiation amount can be relatively decreased. In this case, the support body control unit 802 may control the turning drive unit 642 according to the control profile 830 to change the rotation speed of the X-ray cone beam BX1.

  Further, the change of the X-ray irradiation amount for the subject M1 may be performed by changing both the X-ray intensity output from the X-ray generator 42 and the rotation speed of the X-ray cone beam BX1. In this case, the support body control unit 802 and the irradiation control unit 803 may control the X-ray generator 42 and the turning drive unit 642 according to the control profile 830.

  Note that the control profiles 830a and 830b shown in FIGS. 16 and 17 correspond to the positional relationship between the imaging region ROI and the X-ray high absorption region, but control profiles corresponding to other items may be prepared in advance. Good. For example, "Adult", "Child", "Gender", "Age", "Race", "Body size", "Jaw shape (upper jaw protrusion, lower jaw protrusion, open bite shape, left-right asymmetric shape, etc.)", etc. A control profile according to the physical characteristics of the person M1 may be prepared in advance.

  Returning to FIG. 11, the transparent information generation unit 806 generates transparent information 832. The transmission information 832 is specific information regarding the transmission of X-rays in the subject M1 who is the CT imaging target. The transmission information 832 may be considered to be individual information regarding the degree of X-ray transmission to the subject M1 and the imaging target area, and may be numerical information. The profile changing unit 807 generates the individual-specific control profile 834 by adjusting the control profile 830 selected by the profile selecting unit 805 according to the transparency information 832. The adjustment is performed according to the characteristics of the individual that can be handled by the transparency information 832. The individual-specific control profile 834 is obtained by adding a change according to the characteristics of the individual to the default control profile 830 based on the transparency information 832. Preferably, the adjustment is made in response to the hard tissue characteristics of the individual.

  The adjustment of the X-ray irradiation amount according to the transmission information 832 may be performed by adjusting at least one of the tube current and the tube voltage by the irradiation control section 803, and by adjusting the turning speed of the turning arm 62 by the support body control section 802. May be done. That is, it is performed by controlling at least one of the tube current of the X-ray generator 42, the tube voltage, the turning speed of the turning arm 62 by the turning drive unit 642, the turning range of the turning arm 62, and the range of the imaging region ROI. You may

  The control of the turning range of the turning arm may be performed by adjusting the turning angle range, for example, when the turning angle is 360 °, the turning angle is 180 °, and the X-ray cone beam BX1 is set to 180 °. The fan angle is added to the above, or conversely, a small turning angle is set to a large turning angle.

  The control of the range of the imaging region ROI may be performed by the control of the irradiation range of the X-ray beam by the beam shape adjusting unit 44, that is, the control of the shielding amount. For example, the width of the opening 445 surrounded by the opposite edge portions 443a and 444a of the shielding members 443 and 444 is changed, and the opening width for irradiating the diameter of 40 mm by default is the opening width of irradiating the diameter of 35 mm. Thus, the opening degree is adjusted as described above, or conversely, the small opening width is adjusted so as to have the large opening width. The height or both heights may be adjusted similarly.

  In detail, the following adjustments are made. When the X-ray dose is insufficient with the default tube current, the tube current is increased. When the X-ray dose is insufficient with the default tube current, the tube voltage is increased. When the X-ray dose is insufficient at the default turning speed, the turning speed is reduced. When the X-ray dose is insufficient in the default swivel range, the swivel range is increased. When the default range ROI is too narrow, the range ROI is expanded. When the X-ray dose is excessive with the default tube current, the tube current is lowered. The tube voltage is lowered when the X-ray dose is excessive with the default tube current. When the X-ray dose is excessive at the default turning speed, the turning speed is increased. When the X-ray dose is excessive in the default swivel range, the swivel range is reduced. If the default range ROI is too wide, the range ROI is narrowed.

  As an example, the transmission information 832 may be information regarding the X-ray transmittance obtained based on the X-ray imaging of the subject M1 who is the CT imaging target. Specifically, for example, like the panoramic image and the two-direction scout image shown in FIGS. 13 and 14, from the degree of the X-ray transparency that can be detected from the X-ray image obtained by X-raying the subject M1. The transmission information 832 may be obtained, or the transmission information 832 may be obtained from the intensity of the X-ray received by the X-ray detector 52 during the X-ray imaging of the subject M1.

  The degree of X-ray transparency that can be detected from the X-ray image can be calculated, for example, from the pixel value of the X-ray image. The pixel value of the entire X-ray image may be referred to, or the pixel value of a part of the X-ray image may be referred to. Acquisition of the transmission information 832 based on the pixel value of the horizontal range HR11 shown in FIG. 18 described later is a reference example of a part of pixel values of the X-ray image.

  In order to monitor the intensity of X-rays received by the X-ray detector 52 during X-ray imaging of the subject M1, output data of the entire light receiving area may be monitored, or output data of some pixels in the light receiving area may be monitored. May be monitored. You may make it monitor the sparse part in a pixel. Acquisition of transmission information 832 based on the value of output data 420 shown in FIG. 24, which will be described later, is a reference example of the intensity of X-rays received by the X-ray detector 52 during X-ray imaging.

  Further, for example, the transmission information may be information for informing how the default control profile should be changed as a result of detecting the X-ray transmittance for each individual. For example, if an object M1 is irradiated with X-rays and the amount of received light on the X-ray detection side is larger than the standard, it means that the object has a high transmittance, and a signal to suppress the amount of X-ray irradiation is given. The transmission information becomes transmission information, and if the amount of received light on the X-ray detection side is smaller than the standard, assuming that another subject M1 is irradiated with X-rays in the same range at the same X-ray dose for the same time, the transmittance is Is a low individual, and the signal that should increase the X-ray irradiation amount becomes the transmission information.

  Specifically, the transmission information generation unit 806 may generate the transmission information 832 from the output data 420 output from the X-ray detector 52 when the subject M1 is X-rayed. More specifically, the transmission information generation unit 806 may generate the transmission information 832 from the pixel value that is the output data 420 output by the X-ray detector 52 in pixel units. In this case, the X-ray transmission characteristic of the subject M1 can be appropriately obtained from the pixel value.

  For example, when the subject M1 is a child (particularly, a child up to the secondary symptom stage), the X-ray sensitivity is generally higher than that of an adult. Therefore, when the subject M1 is a child, it is desirable to reduce the X-ray irradiation dose more than when the subject M1 is an adult. Therefore, when the physique information 836 indicates “child”, the transmission information generation unit 806 may generate the transmission information 832 that reduces the X-ray irradiation dose indicated by the control profile 830.

<Aspect of Generating Transmission Information 832 from X-ray Image>
In medical and dental practice, X-ray imaging such as simple X-ray imaging including cephalometric imaging, panoramic X-ray imaging or CT imaging is performed for examining a patient. Panoramic X-ray images and CT images obtained by reconstructing one or more X-ray projection images obtained by each X-ray imaging or a plurality of X-ray projection images (hereinafter, these images are referred to as "X-ray images"). The pixel value of each pixel constituting () indicates the intensity of the X-ray transmitted through the subject M1. That is, the X-ray image acquired in the past includes information on the X-ray transmittance of the subject M1. Therefore, the transmission information 832 can be effectively generated from the X-ray image acquired in the past.

  The data of the X-ray image may be electromagnetically recorded in the server 9 (database system) as medical information 90 for each subject. The medical care information 90 is information specific to the subject who is used for medical treatment of the subject. The medical care information 90 may include information such as age, sex, and treatment history for each subject. The transmission information generation unit 806 may acquire the medical care information 90 corresponding to the subject M1 who is the CT imaging target from the server 9 by information communication (see FIGS. 11 and 12).

  The server 9 in which the medical care information 90 is stored is connected to the communication I / F 84 of the imaging unit 20 via a network such as a hospital LAN. The transparent information generation unit 806 accesses the server 9 via the communication I / F 84, and extracts the medical care information 90 corresponding to the subject M1 to be CT imaged from the plurality of medical care information 90 stored in the server 9. Good to get.

  It should be noted that, in association with the X-ray image, X-ray irradiation amount information, which is information on the X-ray irradiation amount irradiated to the subject in the X-ray imaging that acquires the X-ray image, is recorded as the medical care information 90. Good. The X-ray irradiation amount information includes, for example, the tube current or the tube voltage supplied to the X-ray tube 42T, or the turning speed of the turning arm 62. The transmission information generation unit 806 generates the transmission information 832 using the X-ray dose information together with the X-ray image, so that the X-ray transmission characteristic of the subject M1 can be appropriately obtained.

  The medical care information 90 may include an X-ray image obtained by radiographing the subject M1. This X-ray image can be information, which will be described later, for acquiring the physique information 836 from the X-ray image.

  FIG. 18 is a diagram for explaining an example of generating the transmission information 832 based on the panoramic X-ray image PA1. The pixel value (luminance value) of each pixel forming the panoramic X-ray image PA1 is X-ray detection information indicating the intensity of the X-ray detected by the X-ray detector 52. By using this X-ray detection information, it is possible to appropriately obtain the X-ray transmittance of the subject M1 who is the CT imaging target. In panoramic X-ray photography, the dose irradiated to the subject M1 may be automatically changed according to the projection angle. In this case, the transmission information 832 for the subject M1 may be generated from the pixel value of the panoramic X-ray image PA1 while also considering the variation of the dose.

  The pixel values of the entire panoramic X-ray image PA1 may be used to generate the transmission information 832, but the pixel values of only a partial area of the panoramic X-ray image PA1 may be used. This partial area may be, for example, a horizontal range HR11 that horizontally traverses the panoramic X-ray image PA1 at a specified height position in the panoramic X-ray image PA1. The vertical width of the horizontal region HR11 may have a width dimension of one pixel or two pixels or more.

  The horizontal range HR11 may be a region between the vertical position corresponding to the teeth of the upper jaw and the vertical position corresponding to the nasal cavity in the standard skeleton. This region is generally a portion where the X-ray transmittance of the subject M1 is relatively uniform. Therefore, the horizontal range HR11 is a region suitable for obtaining the transparency information 832.

  FIG. 19 is a diagram showing a pixel value distribution VD1 which is a distribution of pixel values for the subject M1 individual in the horizontal range HR11 shown in FIG. In FIG. 19, the horizontal axis represents the horizontal position on the panoramic X-ray image PA1, and the vertical axis represents the pixel value. The standard pixel value distribution VDS represents the pixel value distribution of the horizontal range HR11 in a standard panoramic X-ray image. The standard panoramic X-ray image is an image obtained by panoramic X-ray imaging of a subject having standard physical characteristics. The pixel value distribution VD1 and the standard pixel value distribution VDS in the horizontal range HR11 have a symmetry centering on the position of the midline.

  In the example shown in FIG. 19, the pixel value distribution VD1 for the subject M1 who is the CT imaging target is generally smaller than the standard pixel value distribution VDS. This is presumed to be that the X-ray transmittance is smaller than the standard (that is, the X-ray attenuation is large) in the subject M1 who is the subject of CT imaging. In this case, the transmission information generation unit 806 may generate transmission information 832 that modifies the control profile 830 so that the X-ray irradiation amount becomes larger than the standard.

  The difference value between the average value of the pixel value distribution VD1 and the average value of the standard pixel value distribution VDS may be used as the transmission information 832. The ratio of the average value of the pixel value distribution VD1 to the average value of the standard pixel value distribution VDS may be used as the transmission information 832. The transparency information 832 may be generated based on a predetermined representative value such as a median value, a maximum value or a minimum value, instead of the average value of these distributions VD1 and VDS.

  Further, as shown in FIG. 18, the transparency information 832 may be generated not only according to the single horizontal range HR11 but also according to the pixel values in the horizontal ranges HR11, HR12, and HR13 at different vertical positions. In this case, the transparency information 832 may be generated according to a representative value such as an average value of pixel values in different horizontal ranges HR11 to HR13.

  FIG. 20 is a diagram showing an individual control profile 834b generated by adjusting the control profile 830b. The profile changing unit 807 adjusts the standard control profile 830b according to the transmission information 832 based on the pixel values on the panoramic X-ray image PA1 shown in FIG. 18, and generates the individual control profile 834b. In the individual-specific control profile 834b, the X-ray irradiation dose is adjusted to be larger than the X-ray irradiation dose indicated by the control profile 830b over the entire turning angle. Here, the X-ray irradiation dose indicated by the individual-specific control profile 834b is raised from the X-ray irradiation dose indicated by the control profile 830b by a constant value over the entire turning angle. When performing such adjustment, the addition value or the subtraction value may be uniformly increased or decreased over all the turning angles, or may be increased or decreased at the same ratio. Needless to say, it is not necessary to perform uniform processing over all turning angles, and it is also possible to apply a process including a change according to the turning angle.

  The degree of adjustment or the adjustment timing may be changed according to the region where the imaging region ROI is set. For example, assume that the actual subject M1 has a larger amount of hard tissue than the standard subject. When the front tooth region is the imaging region ROI, the front tooth region has a small thickness and the difference between the subject M1 and the standard subject is considered to be small. Therefore, the X-ray cone beam BX1 is moved from right to left or vice versa. At the irradiation timing, the adjustment amount for the standard profile is reduced, the molar region is thick, and it is considered that the difference between the subject M1 and the standard subject is large. Therefore, the X-ray cone beam BX1 is moved from right to left. , Or vice versa, the amount of adjustment for the standard profile may be increased.

  When the X-ray transparency is obtained as the transmission information, the action of adjusting the default control profile such as the control profile 830b to generate the individual control profile such as the individual control profile 834b is applied and adjusted by individual. Shall be called. The action of the individual application adjustment may be a calculation such as the increase / decrease described above, or an action of exchanging with a control profile of another individual prepared in advance.

  The irradiation control unit 803 or the support control unit 802 controls the X-ray irradiation dose for the subject M1 based on the individual-specific control profile 834b. That is, the X-ray irradiation dose is controlled so as to match the control profile 830 selected according to the imaging region ROI and the transmission information 832 according to the transmission characteristic of the subject M1. As described above, by generating the individual-specific control profile 834b, CT imaging can be performed with an X-ray irradiation dose suitable for the imaging region ROI of the subject M1.

  When generating the transparency information 832, it is not essential to use the pixel value in a region extending in the horizontal direction such as the horizontal range HR11. For example, the transparency information 832 may be generated from pixel values in the vertically extending region.

  Further, in the example described with reference to FIG. 18, the transmission information 832 is generated based on the panoramic X-ray image PA1 that is the reconstructed image. However, when a plurality of strip-shaped X-ray projection images obtained by panoramic X-ray imaging remain, the transmission information generation unit 806 may generate the transmission information 832 from these X-ray projection images. Since the plurality of X-ray projection images obtained by the panoramic X-ray imaging include the information on the transparency of the subject M1 who is the CT imaging target, the transmission information 832 can be effectively generated from these X-ray projection images.

  FIG. 21 is a diagram for explaining an example of generating the transparency information 832 based on the two-way scout image. The two-direction scout image is composed of a side projection image PI1 and a front projection image PI2. The pixel value (luminance value) of each pixel of the two-direction scout image is also X-ray detection information indicating the intensity of the X-ray detected by the X-ray detector 52. When the side projection image PI1 and the front projection image PI2 have already been obtained in the past X-ray imaging for the subject M1 who is the CT imaging target, the transmission information generation unit 806 uses the transmission information 832 from these images PI1 and PI2. May be generated.

  For example, as illustrated in FIG. 21, the transparency information generation unit 806 may generate the transparency information 832 from pixel values in the horizontal range HR21 that extends in the horizontal direction at a specified vertical position on the images PI1 and PI2. Specifically, similar to the example described in FIG. 18, the pixel values in the horizontal range HR21 on the images PI1 and PI2 of the subject M1 as the CT imaging target and the side projection in the case of the standard subject. The transparency information 832 is obtained from the pixel values in the horizontal range HR21 on the image and the front projection image. The transparency information 832 may be generated using not only the single horizontal range HR21 but also pixel values in the horizontal ranges HR22 and HR23 at different vertical positions.

  Further, the transmission information 832 may be generated from a one-direction scout image (specifically, the side projection image PI1 or the front projection image PI2) obtained by shooting from one direction.

  The transparency information 832 may be information regarding the X-ray transparency of the imaging region ROI (local imaging region) set by the region setting unit 801 via the operation display unit 82. Specifically, in the X-ray image such as the panoramic X-ray image PA1, the transmission information 832 may be generated from the pixel value of the image portion corresponding to the imaging region ROI targeted for CT imaging. In this case, the transparency of the imaging region ROI of the subject M1 can be obtained based on the actual X-ray imaging. Therefore, CT imaging can be performed with an appropriate X-ray irradiation amount for the imaging region ROI.

  FIG. 23 is a diagram showing another example of application adjustment for each individual. FIG. 23 shows a manner in which the imaging region ROI is set to a molar as in the case described with reference to FIG. Now, it is assumed that the standard profile is prepared for the standard subject's jaw J1a, and the jaw of the subject M1 actually subjected to X-ray CT imaging is the jaw J1b. The jaws J1a and J1b are shown by lines for easy understanding of the drawing. The cervical vertebra HA1 is also shown smaller than that shown in FIG. 17 for emphasis.

  Since the description has been given with reference to FIG. 17, the description of all the rotations of the rotation arm 62 is omitted, and the description will focus on the differences between the imaging of the jaw J1a and the imaging of the jaw J1b. It is assumed that the revolving arm 62 revolves with respect to the jaw J1a, and the phase FA in which the X-ray cone beam BX1 irradiating the imaging region ROI contacts the cervical vertebra HA1 starts slightly after the revolving angle of 90 °. On the other hand, when the right molar of the jaw J1b is set as the imaging region, the phase FB in which the X-ray cone beam BX1 irradiating the imaging region ROI contacts the cervical vertebra HA1 starts slightly before the turning angle of 90 °. . Therefore, in this embodiment, the peak of the irradiation amount is adjusted to be shifted earlier than the standard. Specifically, the illustrated individual control profile 834c is generated.

  As shown in FIG. 14, when the imaging region ROI that is the CT imaging target is set on the two-direction scout image, the position of the posterior tooth is input in the front projection image PI2, and the specific number of the posterior tooth is specifically input through the interface. It may be a tooth or an input may be accepted by the device side, and the necessity of individual application adjustment may be judged from the difference in coordinates between the standard jaw J1a and the molar. Further, through the interface, it may be possible to accept an input that the width of the jaw J1b of the actual subject M1 is narrower than the width of the standard jaw J1a and perform the individual application adjustment. In addition, for example, the right and left widths of a general jaw may differ depending on races, and generally, there are many U-shaped jaws depending on race, or a U-shaped jaw close to a V-shape. Since there are many cases, it is possible to accept input by race type.

  In the case of a dental X-ray radiographing apparatus, the method of fixing the jaw tip on the chin rest or fixing the examinee by biting the fixing bite element with the front teeth is often adopted, so that the front tooth region has the left and right widths of the jaw J1b. Although it is narrow, it is often not affected by the positional relationship with the cervical vertebra HA1, and it is not necessary to adjust the movement of the peak as in the case of a molar.

  For the same reason, when the front tooth region is set as the imaging region ROI, there is almost no positional change between the jaw J1a and the jaw J1b in any case, and the position control of the rotary shaft 65 can be common, but the posterior region is the imaging region. In the case of the ROI, the coordinates of the existing position of the molar in the three-dimensional space are different between the jaw J1a and the jaw J1b. Therefore, the moving amount of the rotary shaft 65 is changed for the molars of the jaw J1b.

  The above-described embodiment is also an example of individual application adjustment in which the degree of adjustment or the adjustment timing is changed according to the region where the imaging region ROI is set.

  Since the default control profile described above may be prepared in multiple layers, for example, each of the control profiles for each sex and age group may be further subdivided into the control profiles for each jaw shape.

  FIG. 22 is a diagram for explaining another example of generating the transmission information 832 based on the panoramic X-ray image PA1. In the example illustrated in FIG. 22, the transparency information generation unit 806 generates the transparency information 832 using the pixel values of the plurality of regions HR31 that are discrete in the horizontal direction. Each of the plurality of regions HR31 may have a size of a single pixel forming the panoramic X-ray image PA1, or may have a size including a plurality of unit pixels. The transparency information 832 may be generated from pixel values of pixels included in the plurality of regions HR31. As a modification of this, for example, the transparency information 832 may be generated from pixel values of a plurality of regions discrete in the vertical direction or pixel values of a plurality of regions discrete in a direction different from the horizontal direction and the vertical direction. .

<Aspect of Generating Transmission Information 832 During CT Imaging>
As another example of generating the transmission information 832, the output data 420 output from the X-ray detector 52 may be used during CT imaging of the subject M1. The output data 420 indicates the intensity of the X-ray that has passed through the subject M1 and reached the X-ray detector 52. During CT imaging, that is, while the swing drive unit 642 rotates the swing arm 62, the transmission information generation unit 806 monitors the output data 420 output from the X-ray detector 52, and the X indicated by the output data 420 is displayed. Transmission information 832 is generated according to the line intensity (see FIG. 12). The profile changing unit 807 generates the individual-specific control profile 834 according to the transmission information 832, so that the X-ray irradiation dose can be controlled during CT imaging.

  FIG. 24 is a diagram showing an individual control profile 834b generated during CT imaging. Here, the imaging region ROI is set in the left molar region of the jaw J1. The subject M1 has a metal prosthesis MP1 on the right molar. The metal prosthesis MP1 has a significantly high X-ray absorption rate. Therefore, the X-ray cone beam BX1 overlaps with the metal prosthesis MP1 so that the intensity of X-rays detected by the X-ray detector 52 is greatly attenuated. In the CT imaging shown in FIG. 24, the transmission information generation unit 806 monitors the output data 420 from the X-ray detector 52. Then, when the transmission information generation unit 806 determines that the output data 420 has attenuated the X-ray intensity, the transmission information generation unit 806 generates the transmission information 832 for increasing the X-ray irradiation dose for the subject M1.

  Here, X-ray irradiation is performed immediately after the start of turning (turning angle 0 °) to turning angle Ang1 (<90 °) and between turning angle Ang2 (> 90 °) and ending turning (turning angle 180 °). Transmission information 832 is generated that increases the amount. The amount of X-ray irradiation is increased because the metal prosthesis MP1 appears in the irradiation path of the X-ray cone beam BX1 from immediately after the start of turning until the turning angle Ang1 and from the turning angle Ang2 to the end of turning. This is because the metal prosthesis MP1 appears next to the cervical vertebra HA1 in the irradiation path of the X-ray cone beam BX1. Based on the generated transmission information 832, the profile changing unit 807 changes the control profile 830b for the right molar in real time to generate the individual control profile 834b2.

  When changing the X-ray irradiation dose indicated by the original control profile 830 according to the transmission information 832, the profile changing unit 807 limits the variation amount from the X-ray irradiation dose indicated by the original control profile 830 to within twice. May be. For example, in the individual control profile 834b2 shown in FIG. 24, the X-ray irradiation dose is suppressed to twice the X-ray irradiation dose of the original control profile 830 between the turning angle Ang2 and the turning angle 180 °. When the irradiation control unit 803 controls the X-ray generator 42 based on the individual control profile 834b2, the X-ray irradiation amount irradiated to the subject M1 in CT imaging is the X-ray indicated by the original control profile 830. It is suppressed within twice the dose. This can reduce the X-ray exposure of the subject M1. The same applies when the support body control unit 802 controls the turning drive unit 642 based on the individual-specific control profile 834b2.

  Regarding the configuration in which the adjustment of the X-ray irradiation amount is not performed indefinitely and is limited to, for example, not more than double as described above, if such a limitation is not provided, the X-ray absorption rate of the metal prosthesis MP1 is very high. Since it is high, the X-ray irradiation dose may be excessively increased in an attempt to compensate for that amount. Then, the amount of X-ray exposure of the subject M1 becomes enormous. Further, since the X-ray irradiation amount is too strong, there is a possibility that an image of a portion having low density of hard tissue or a soft tissue portion may be skipped. When the X-ray irradiation amount is increased, the X-ray irradiation is often blocked to a considerable extent by the metal prosthesis MP1. If so, the X-ray irradiation amount can be controlled by limiting the adjustment amount or the fluctuation amount of the X-ray irradiation amount. While supplementing, the X-ray exposure dose of the subject M1 can be reduced and images can be secured.

  Further, the profile changing unit 807 may change the control profile 830 so that the X-ray irradiation amount falls within the range (adjustment range RR1) between the specified lower limit value V1 and the specified upper limit value V2. (See FIG. 24). This makes it possible to keep the X-ray irradiation amount within the specified adjustment range RR1. For example, the X-ray exposure of the subject M1 can be reduced by suppressing the X-ray irradiation amount to the prescribed upper limit value V2 or less. Further, by setting the X-ray irradiation amount to the specified lower limit value V1 or more, it is possible to suppress deterioration of the image quality of the CT image due to insufficient X-ray irradiation amount.

  A configuration example in which the example of FIG. 18 is applied based on the configuration for adjusting the X-ray irradiation dose as shown in FIG. 24 can be considered. If the analysis of the horizontal range of the panoramic X-ray image PA1 in FIG. 18 is further increased, the position where a high X-ray absorber (X-ray high absorption region) such as a metal prosthesis exists can be detected. FIG. 25 is a diagram schematically showing the panoramic X-ray image PA2. Since the positional relationship between the X-ray path and the high X-ray absorber can be calculated in advance with respect to the designated position of the imaging region ROI, an individual control profile as shown in FIG. 24 can be prepared at this point. . Instead of the analysis of the horizontal range of the panoramic X-ray image PA1, the operator may be allowed to accept the position designating operation of the high X-ray absorber for the panoramic X-ray image PA1. Further, instead of the position specifying operation of the high X-ray absorber, the position information of the high X-ray absorber may be introduced, for example, the position information of the high X-ray absorber of the electronic medical record may be introduced. Good.

  The brightness of the image of the metal prosthesis MP1 in the panoramic X-ray image PA1 may be reflected in the adjustment of the individual control profile. For example, from the brightness of the image of the metal prosthesis MP1, it is possible to detect that this image portion is a metal prosthesis, and it is determined that the position of the image of the metal prosthesis MP1 is the position where the metal prosthesis MP1 exists. Keep it possible. Based on the information, the control profile 830 is adjusted. If it can be determined from the detected brightness that the X-ray irradiates both the metal prosthesis MP1 and the imaging region ROI and is still transmissive, it is not necessary to increase the X-ray irradiation amount, but preferably the figure Adjust by an amount that does not raise as described in 24. Further, the size of the image of the metal prosthesis MP1 may be referred to. For example, although the metal prosthesis MP1 is a high X-ray absorber in terms of brightness than the image, it is small in size, thin in shape, If it is possible to determine that the X-ray irradiates both the metal prosthesis MP1 and the imaging region ROI and is still transmissible due to a small size, the X-ray irradiation amount is adjusted to be increased similarly. Good. When it is determined from the image of the metal prosthesis MP1 that X-rays are not transmitted, the same control as that described with reference to FIG. 24 may be performed. If it is determined from the image of the metal prosthesis MP1 that X-rays are not transmitted, the adjustment may be stopped. That is, in any case, it is determined that the X-rays do not pass through, so that the irradiation X-ray dose need not be replenished.

  When the position of the metal prosthesis MP1 overlaps the imaging region ROI, the X-ray irradiation amount may be increased within a range in which the image of the tissue around the metal prosthesis MP1 does not fly. The range (upper limit value and lower limit value) of the X-ray irradiation dose in this case may be determined in advance.

  The above control can be applied even when there are a plurality of metal prostheses MP1. FIG. 26 is a diagram schematically showing a panoramic shot image PA3 including a plurality of metal prostheses MP1. As shown in FIG. 26, a plurality of metal prostheses MP1 covers a part of the lower right 7th and 6th molars, and the imaging region ROI is in the lower right approximately 2nd to 4th tooth regions. It is set.

  FIG. 27 is a schematic plan view showing how the imaging region ROI shown in FIG. 26 is irradiated with the X-ray cone beam BX1. In the positional relationship between the imaging region ROI and the two metal prostheses MP1 shown in FIG. 26, the issue of how to adjust the X-ray irradiation dose becomes a problem, as shown in FIG. Irradiation is performed from the direction of approximately 11 o'clock or a direction opposite to that of 180 °, and it is the timing when the plurality of metal prostheses MP1 and the imaging region ROI are aligned on the X-ray path. When the X-ray irradiates both the metal prosthesis MP1 and the imaging region ROI and it can be determined that the X-ray can still be transmitted, the X-ray irradiation amount may be adjusted to the same degree.

  FIG. 28 is a modification of the embodiment shown in FIG. The control profile 830c shown in FIG. 28 is basically the same as the configuration example of the control profile 830a shown in FIG. 16, except that a sub peak of the X-ray irradiation dose is added near the turning angle 55 °. Is different. This swivel angle has a sub-peak because at this swivel angle, the rows of teeth on the dental arch overlap, and the longitudinal direction of the jaw bone in the irradiation range is the timing along the X-ray irradiation direction. This is because when viewed from the X-ray projection direction, it becomes thick hard tissue (X-ray high absorption region), and the X-ray irradiation amount to the target imaging region ROI becomes insufficient. The position where the sub peak should be determined also differs depending on the position of the imaging region ROI, and such a control profile 830c has a preset imaging region ROI and a preset cervical spine HA1 (high X-ray absorption). In addition to the positional relationship with the (region), the X-ray irradiation amount according to another hard tissue influenced by the X-ray irradiation direction is defined. Such hard tissue may be a dentition, a jawbone, a palatal bone, or the like, and may be a setting target.

  When adjusting the control profile 830c of FIG. 28, unlike the configuration example of FIG. 24, even if the metal prosthesis MP1 appears in the path of the X-ray, it can be configured to be ignored. The transmission information generation unit 806 monitors the output data 420 output from the X-ray detector 52 during CT imaging and generates the transmission information 832 according to the X-ray intensity indicated by the output data 420, but a threshold value is provided. From the intensities of the output data of the respective parts in the X-ray frame image acquired at any time, it is discriminated whether the area is projected on the metal prosthesis or the area projected on the hard tissue such as bone or tooth. The area that was projected onto the metal prosthesis is referred to as a metal projection area, and even if there is a metal projection area, the X-ray irradiation dose is not adjusted. The area that has been projected onto the hard tissue is tentatively called a hard tissue projection area, and the transmission information 832 is generated for the hard tissue projection area according to the X-ray intensity indicated by the output data 420. If the metal prosthesis is being adjusted, the amount of adjustment will be excessive and should be ignored. Furthermore, by setting a threshold value, the region where there is no tissue or the region where there is a small amount of soft tissue but there is a projection to a spatial region that is almost space is discriminated, and the region where there is a projection to the spatial region is temporarily defined as the spatial projection region. The X-ray irradiation amount may not be adjusted even if there is a spatial projection region. If the adjustment is made to the spatial region, the adjustment amount becomes excessively thin or the X-ray irradiation is not performed, so that it is ignored. It may be so arranged that the comparison with the reference value is made only in the vicinity of the turning angle 55 ° shown in FIG.

  FIG. 29 is a schematic front view showing the detection surface 52S of the X-ray detector 52. In CT imaging in which a part of the jaw J1 is the imaging region ROI, the X-rays are incident only on the light receiving region RA1 which is a part of the detection surface 52S that can detect the X-rays in the X-ray detector 52. In this case, when the transmission information 832 is generated during CT imaging, the transmission information generation unit 806 monitors only the intensity of the X-ray detected in all or part of the light receiving region RA1 of the detection surface 52S. You may In this case, the transmission information generation unit 806 may monitor the average value of the output data 420 (X-ray intensity) output from all or some of the detection elements of the light receiving area RA1.

  The transmission information generation unit 806 may generate transmission information 832 that changes the control profile 830 so that the intensity of the X-ray indicated by the output data 420 is constant. In this case, since the pixel values can be made uniform among a plurality of X-ray projection images obtained by CT imaging, the influence of the high X-ray absorber can be reduced.

<Aspect of Generating Transparent Information 832 from Physical Information 836>
As another example of generating the transparency information 832, the physique information 836 may be used. The physique information 836 is information indicating the size of the physique of the subject M1 who is the CT imaging target. The transparency information generation unit 806 may acquire the physique information 836 and generate the transparency information 832 based on the physique information 836. Generally, the larger the physique of the subject M1, the lower the X-ray transmittance. Therefore, the transmission information generation unit 806 generates the transmission information 832 according to the physique information 836, so that CT imaging can be performed with an X-ray irradiation dose suitable for the physique of the subject M1.

  As an example of acquiring the physique information 836, the operator performs an operation of designating the physique of the subject M1 via the operation display unit 82, and the transparent information generation unit 806 acquires the physique information 836 in accordance with the operation input. (See FIG. 12). In this case, in order to facilitate selection of the physique by the operator, a plurality of options indicating the physique (for example, items such as “old man”, “adult”, “child”, etc. according to age, gender such as “male”, “female”) May be displayed on the operation display unit 82. Then, the transparent information generation unit 806 may acquire, as the physique information 836, the item selected by the operator from the plurality of options according to the subject M1.

  As another example of acquiring the physique information 836, the transparency information generation unit 806 may acquire the physique information 836 from the medical care information 90 of the subject M1 who is the target of CT imaging (see FIG. 12). Specifically, the physique information 836 may be generated from the information contained in the medical care information 90, such as age, sex, height, and weight, which directly or indirectly indicates the physique.

  The transmission information generation unit 806 may acquire the physique information 836 from the X-ray image included in the medical care information 90. For example, the size of a characteristic part (for example, lower jaw, upper jaw, teeth, etc.) shown as an image in a panoramic image or a CT image is acquired by a known image recognition process, so that the physique of the subject M1 can be estimated. The transparency information generation unit 806 may acquire the physique information 836 based on this image recognition processing. As the X-ray image, in addition to a panoramic image and a CT image, a one-way scout image obtained by photographing the subject M1 from one direction, and a two-way scout image obtained by photographing the subject M1 from two directions are conceivable. The physique information 836 may be obtained from at least one image of the one-way scout image, the two-way scout image, and the panoramic image.

  FIG. 30 is a diagram showing individual-specific control profiles 834L, 834M, 834S generated according to the physique information 836. When a relatively large L size, a medium M size, and a relatively small S size are defined as the size of the subject's physique, the physique information 836 is information indicating one of these three physique sizes. It is said that The individual control profiles 834L, 834M, 834S shown in FIG. 30 indicate the X-ray irradiation dose corrected based on the transmission information 832 corresponding to the body size information 836 based on the front tooth control profile 830a. The individual-specific control profiles 834L, 834M, and 834S correspond to the case where the body size of the subject M1 is L size, M size, and S size in order. Here, the control profile 830a defines the X-ray irradiation dose when the subject is M size. Therefore, the individual control profile 834M matches the control profile 830a.

  As shown in FIG. 30, when the physique of the subject M1 is L size, CT imaging can be performed with a relatively large X-ray irradiation amount based on the individual control profile 834L. In contrast, when the body size of the subject M1 is S size, CT imaging can be performed with a relatively small X-ray irradiation amount based on the individual control profile 834S.

  The transparency information generation unit 806 may acquire the physique information 836 from the subject holding unit 72 (see FIG. 12). The subject holding unit 72 contacts the head MH of the subject M1 who is the CT imaging target and holds the head MH at a fixed position. From the position of the subject holding unit 72 in contact with the head MH (specifically, the positions of the chin rest 722 and the head holder 723 in contact with the head MH), the physique of the subject M1 can be measured. In this case, the chin rest 722 and the head holder 723 are configured to be displaceable with respect to the base of the subject holding unit 72, and a measurement unit that measures the amount of displacement of the chin rest 722 and the head holder 723 is provided. For example, it is possible to actually measure that the head having a large left and right diameter has a large opening on the left and right of the head holder 723 as compared with a head having a small left and right diameter, and has a large physique.

  Returning to FIG. 11, a notification unit 86 is connected to the main body control unit 80. The notification unit 86 includes an output device that notifies the operator that the subject M1 who is the CT imaging target has a pediatric physique. The output device includes a lamp that lights up, a speaker that outputs sound, a display that displays an image, and the like. The operation display unit 82 may function as the notification unit 86. To determine whether or not the subject M1 has a pediatric physique, the above-mentioned physique information 836 may be used. For example, a child up to the secondary symptom stage (specifically, a child younger than 17 years old) generally has a higher X-ray sensitivity than an adult, so it is desirable to keep the X-ray irradiation dose low. From this point of view, when the physique information 836 indicates the pediatric physique, the operator easily notifies the subject M1 of the CT imaging that the physique is pediatric by the notification unit 86 performing a predetermined notification. Can be recognized by.

  When the subject M1 has a pediatric physique, the notification unit 86 may perform a recommended notification that recommends reducing the X-ray irradiation dose in CT imaging. Specifically, the recommended notification is a display recommending that the voltage supplied to the X-ray generator 42 be reduced, a display recommending that the current be reduced, and an increase in the rotation speed of the rotation arm 62. It is advisable to perform a display, a display recommending that the range of rotation of the turning arm 62 be reduced, and a display recommending that the imaging region ROI be made as small as possible.

  In this way, by the notification by the notification unit 86, the operator can be urged to execute the X-ray imaging with the X-ray irradiation amount suppressed by the X-ray imaging apparatus 10. Thereby, the X-ray irradiation dose when the subject M1 has a pediatric physique can be effectively reduced.

  The operator may perform an operation of designating one control profile 830 on the operation display unit 82, and the profile selection unit 805 may select the control profile 830 based on the designation operation. Further, as the control profile 830, one or more pediatric control profiles in which the X-ray irradiation dose is set lower than the standard control profile 830 may be prepared in advance. The X-ray dose shown by the child control profile 830 may be, for example, half or less of the X-ray dose shown by the standard control profile 830. Then, the profile selection unit 805 may select one of the plurality of child-specific control profiles 830 based on a predetermined operation by the operator. In this case, when the subject M1 who is the subject of CT imaging is a child, or when the notification unit 86 makes a recommended notification to reduce the X-ray irradiation amount, the operator specifies the control profile 830 for children. Therefore, the X-ray exposure of the subject M1 who is a child can be reduced. After applying the control profile 830 for children, the transmission information 832 for each individual regarding the X-ray transmittance, which is obtained on the basis of the X-ray imaging of the subject M1 as described above, is generated. It may be configured to control the X-ray irradiation dose.

<Image processing device 30>
The hardware configuration of the image processing apparatus 30 is similar to that of a general computer or workstation. That is, the image processing apparatus 30 includes a CPU that performs various arithmetic processes, a ROM that is a read-only memory that stores a basic program, and a RAM that is a readable / writable memory that stores various types of information. The CPU operates according to the control program to function as the control unit 31. The control unit 31 is connected to the image processing unit 33 and the storage unit 35. The image processing unit 33 generates an X-ray transmission image generated based on a signal output by the X-ray detector 52 (or the X-ray detector 664 of the cephalometer unit 66) when the imaging unit 20 executes X-ray imaging. Process to obtain an X-ray image. The storage unit 35 stores an application (program) or data.

  The image processing unit 33 is a function realized by the CPU operating according to an application. The image processing unit 33 may be realized by a GPU (Graphics Processing Unit).

  For example, when panoramic X-ray imaging is performed by the imaging unit 20, the image processing unit 33 performs arithmetic processing to acquire a panoramic image in which a target slice is imaged. Specifically, the image processing unit 33 joins together a plurality of strip-shaped X-ray projection images acquired by the imaging unit 20 to generate one panoramic image corresponding to the dental arch.

  When the CT imaging is performed by the imaging unit 20, the image processing unit 33 executes various processes (filtering process, backprojection process, etc.) on the acquired X-ray projection images to extract the imaging region. An image (CT image) showing each slice when sliced at an arbitrary position is generated.

  The control unit 31 is connected to a display unit 32 that displays images showing various kinds of information, and an operation unit 34 for an operator to input an operation. Further, the image processing device 30 and the main body control unit 80 are connected to each other via the communication I / Fs 36 and 84 so that information can be communicated with each other. The communication I / Fs 36 and 84 are examples of communication units that enable communication with the server 9.

  The image processing device 30 may include some or all of the functions of the main body control unit 80. That is, the image processing device 30 may include the processing units 800-807. Similarly, the main body control unit 80 may include some or all of the functions of the image processing device 30.

<2. Modification>
Although the embodiment has been described above, the present invention is not limited to the above-described one, and various modifications can be made.

  In the above-described embodiment, the plurality of control profiles 830 correspond to the positions of the photographing region ROI, but this is not essential. For example, when targeting a region where the entire dental arch fits, or when targeting a region where the entire jaw fits, as the local imaging region, for each direction with respect to the cervical vertebra HA1, such as the anterior tooth region and the molar region. Since it is not necessary to consider the control, the plurality of control profiles 830 may be set according to the size of the physique.

  In this case, the transmission information 832 may be information indicating the distribution of the X-ray high absorption region. For example, by generating the transmission information 832 indicating the distribution of the X-ray high absorption region for each subject, the individual control profile 834 according to the distribution of the X-ray high absorption region in the subject can be generated. The X-ray high absorption region is, for example, the cervical vertebra HA1 and the metal prosthesis MP1 (cover, bridge, denture, implant, bolt, etc.). The position of the cervical vertebra HA1 may be set based on the size of the physique indicated by the physique information 836, for example. Further, the metal prosthesis MP1 may be set from the record of the medical care information 90, for example. By generating the transmission information 832 according to the distribution of the X-ray high absorption region, it is possible to perform CT imaging with the X-ray irradiation amount according to the X-ray high absorption region of the subject M1.

  In the above-described embodiment, the physique information 836 is used to generate the transparency information 832. However, the control profile 830 itself selected by the profile selection unit 805 may be prepared for each physique. For example, the operator performs an operation of selecting from a plurality of options indicating a physique, and the profile selection unit 805 selects a control profile that is suitable for the selected physique. In this case, similarly to the first embodiment, a control profile 830a corresponding to an imaging region ROI such as an anterior tooth or a posterior tooth is further selected as a local imaging region for a dental arch partial region or a jaw partial local region. The unit 805 can be selected. In this way, the individual transmission information 832 regarding the X-ray transmittance, which is obtained based on the X-ray imaging of the subject M1 as the subject as described above, may be generated.

  Although the present invention has been described in detail, the above description is illustrative in all aspects, and the present invention is not limited thereto. It is understood that innumerable variants not illustrated can be envisaged without departing from the scope of the invention. The configurations described in the above-described embodiments and modified examples can be appropriately combined or omitted as long as they do not contradict each other.

9 servers (database)
10 X-ray imaging device 20 Imaging unit 22 X-ray room 30 Image processing device 40 X-ray generation unit 42 X-ray generator 42T X-ray tube 420 Output data 44 Beam shape adjustment unit 50 X-ray detection unit 52 X-ray detector 52S detection Surface 62 swivel arm (support)
642 Swiveling drive section 644 Horizontal drive section 646 Vertical drive section 65 Rotation axis 65A Rotation axis line 72 Subject holding section 722 Tin rest 723 Head holder 80 Main body control section 801 Area setting section 802 Support control section 803 Irradiation control section 805 Profile selection section 806 Transparent Information generation unit 807 Profile change unit 82 Operation display unit 820 Area setting reception unit 83 Storage unit 830, 830a, 830b, 830c Control profile 834, 834b, 834b2, 834L, 834M, 834S Individual control profile 86 Notification unit 90 Medical information 832 Transmission information 836 Physical information BX1 X-ray cone beam HA1 Cervical vertebra (high X-ray absorption region)
I10 Illustration image J1 Jaw M1 Subject (subject)
MH head MP1 metal prosthesis PA1, PA2, PA3 panoramic X-ray image PI1 side projection image (part of two-direction scout image)
PI2 Front projection image (part of 2-way scout image)
RA1 light receiving area ROI shooting area RR1 adjustment range

Claims (22)

A medical CT imaging device,
An X-ray generator for generating an X-ray cone beam,
An X-ray detector for detecting the X-ray cone beam from the X-ray generator;
A support portion that supports the X-ray generator and the X-ray detector in an opposed manner;
A swivel drive unit that swivels the support unit around a predetermined swivel axis in a state where a subject is placed between the X-ray generator and the X-ray detector;
A storage unit that stores a plurality of control profiles for controlling the X-ray irradiation amount according to a local imaging region that is a part of the subject;
A region setting reception unit that receives the setting of the local imaging region,
A profile selection unit that selects a control profile corresponding to the local imaging region received by the region setting reception unit from the plurality of control profiles,
A transmission information generation unit that generates transmission information regarding transmission of X-rays regarding the subject;
A control unit that controls the X-ray irradiation dose to the subject based on the control profile selected by the profile selection unit and the transmission information generated by the transmission information generation unit;
A medical CT imaging apparatus comprising: The medical CT imaging apparatus according to claim 1, wherein
The medical CT imaging apparatus, wherein the transmission information is information regarding X-ray transmission of the local imaging region received by the region setting reception unit. The medical CT imaging apparatus according to claim 1 or 2, wherein
The medical CT imaging apparatus, wherein the transmission information is information indicating the distribution of the X-ray high absorption region. The medical CT imaging apparatus according to any one of claims 1 to 3,
A region size setting receiving unit that receives a size setting of the local imaging region of the subject,
Further equipped with,
The medical CT imaging apparatus, wherein the control unit selects the control profile according to the size of the local imaging region received by the region size setting receiving unit. The medical CT imaging apparatus according to any one of claims 1 to 4,
The medical CT imaging apparatus, wherein the transmission information generation unit generates the transmission information from output data output from the X-ray detector in X-ray imaging of the subject performed in advance. The medical CT imaging apparatus according to any one of claims 1 to 5,
The medical CT imaging apparatus, wherein the transmission information generation unit generates the transmission information from pixel values output by the X-ray detector in pixel units. The medical CT imaging apparatus according to any one of claims 1 to 6,
The medical CT imaging apparatus, wherein the transmission information generation unit generates the transmission information from output data output by the X-ray detector while the swing drive unit rotates the support unit. The medical CT imaging apparatus according to any one of claims 1 to 7,
The medical CT imaging apparatus, wherein the transmission information generation unit generates the transmission information from physique information that is information about the physique of the subject. The medical CT imaging apparatus according to claim 8, wherein
The transmission information generation unit captures a panoramic X-ray image of the subject in one direction, a one-direction scout image obtained by photographing the subject in two directions, a two-direction scout image obtained by photographing the subject in two directions. A medical CT imaging apparatus that acquires the physique information from at least one of the obtained panoramic images. The medical CT imaging apparatus according to claim 8 or 9, wherein
A communication unit that performs information communication with a database system that stores medical information used for medical treatment of the subject,
Further equipped with,
The transparent information generation unit is a medical CT imaging apparatus that acquires the physique information from the medical care information acquired by the communication unit. The medical CT imaging apparatus according to any one of claims 8 to 10, wherein:
A subject holding unit that contacts the subject and holds the subject in a fixed position;
Further equipped with,
The medical CT imaging apparatus wherein the transmission information generation unit acquires the physique information based on a position where the subject holding unit is in contact with the subject. The medical CT imaging apparatus according to any one of claims 1 to 11,
The medical CT imaging apparatus, wherein the control unit limits the amount of variation from the X-ray irradiation amount indicated by the control profile to within 2 times and controls the X-ray irradiation amount to be applied to the subject. The medical CT imaging apparatus according to any one of claims 1 to 12,
The control unit controls at least one of the tube current of the X-ray generator, the tube voltage, or the rotation speed of the support unit by the rotation drive unit so that the X-ray irradiation amount falls within a predetermined adjustment range. A medical CT imaging device to control. The medical CT imaging apparatus according to any one of claims 1 to 13,
The medical CT imaging apparatus, wherein the area setting reception unit includes an operation display panel that displays an illustration of a dental arch and receives an operation of setting the local imaging area on the illustration. The medical CT imaging apparatus according to claim 8, wherein
When the physique information indicates that it is a pediatric physique, a notification unit that performs notification indicating the pediatric physique,
A medical CT imaging apparatus further comprising: The medical CT imaging apparatus according to claim 15,
The notification indicating the pediatric physique includes reduction of the tube current supplied to the X-ray generator, reduction of the tube voltage, reduction of the swing range of the support portion, acceleration of the swing of the support portion, and local imaging area. A medical CT imaging apparatus, which is a display for instructing an operator to perform at least one of size reduction. The medical CT imaging apparatus according to claim 15 or claim 16,
The profile selection unit, based on the operation input from the operator, it is possible to select a control profile for children from the plurality of control profiles,
When the profile selection unit selects the child-specific control profile, the control unit controls the X-ray irradiation dose based on the child-specific control profile and the transmission information. . The medical CT imaging apparatus according to claim 5, wherein
A medical CT imaging apparatus in which the X-ray imaging performed in advance is panoramic X-ray imaging for obtaining a panoramic image of the subject. The medical CT imaging apparatus according to claim 5, wherein
The medical CT imaging apparatus, wherein the X-ray imaging performed in advance is bidirectional scout imaging to obtain a bidirectional scout image obtained by imaging the subject from two directions. An X-ray generator that generates an X-ray cone beam, an X-ray detector that detects the X-ray cone beam from the X-ray generator, a support that supports the X-ray generator and the X-ray detector in an opposed manner. CT imaging in a medical CT imaging apparatus including a scanning unit and a swivel drive unit that swivels the support unit around a predetermined swivel axis in a state where an object is placed between the X-ray generator and the X-ray detector. A medical CT imaging method for performing:
(A) a step of preparing a plurality of control profiles for controlling the X-ray irradiation dose corresponding to a local imaging region which is a part of the subject;
(B) accepting the setting of the local imaging region,
(C) selecting a control profile corresponding to the local imaging region received in step (b) from the plurality of control profiles;
(D) generating transmission information regarding X-ray transmission of the subject;
(E) rotating the support part while irradiating the subject with an X-ray cone beam from the X-ray generator;
Including,
The step (e) includes
(E1) medical CT imaging including a step of controlling the X-ray irradiation dose to the subject based on the control profile selected in the step (c) and the transmission information generated in the step (d) Method.   21. A computer-readable program that causes the computer to execute the medical CT imaging method according to claim 20, when the CPU of the computer executes the program on a memory.   A computer-readable recording medium, wherein the program according to claim 21 is recorded.