JP4724760B2 - X-ray equipment - Google Patents

Description

  The present invention enables an X-ray to be generated by selectively switching between an X-ray slit beam and an X-ray wide-area beam, and an X-ray imaging apparatus that takes two types of tomographic images according to the X-ray beam. It is about improvement.

  Recently, as an X-ray detector for measuring an X-ray to obtain an X-ray image, a two-dimensional image sensor having a short light receiving portion close to a square and a line type having a longer light receiving portion. Two types of image sensors are available.

  Many of the former digital X-ray imaging apparatuses using a two-dimensional image sensor are configured to use the image sensor as an alternative to a conventional X film, and such X-ray imaging apparatuses are already known. The imaging principle of various transmitted images and tomographic plane images is used.

  On the other hand, a digital X-ray imaging apparatus using the latter line-type image sensor irradiates a subject with an X-ray slit beam according to a predetermined imaging trajectory, and tracks the X-rays transmitted through the subject with a line-type image sensor. Then, after taking a number of strip-shaped X-ray images, the X-ray images are connected and arranged in time series to obtain a single X-ray image.

  Patent Documents 1 and 2 below disclose an X-ray imaging apparatus that performs panoramic X-ray imaging using a line-type image sensor.

  That is, Patent Document 1 discloses one that can freely select panoramic X-ray imaging using a film cassette and panoramic X-ray imaging using a digital sensor cassette. The digital sensor cassette includes a line-type image sensor. Is being used.

  In Patent Document 2, an electric X-ray image detector, which is a line-type image sensor, is disposed on the inner surface of an X-ray light receiving unit provided in the center of the front surface of the cassette housing, and a control signal corresponding to the turning of the turning arm. Is configured to be able to output an image signal necessary for generating a panoramic X-ray image in the form of a digital signal by electrically controlling the X-ray into an electric signal.

  In Patent Document 3, a patient frame that holds and fixes a patient's head can be freely moved up and down, and a relative position displacement with respect to a turning arm that turns around the patient frame can be performed so that a desired part can be photographed. A medical X-ray imaging apparatus is disclosed. As an X-ray image sensor, a MIS type has recently been developed (Patent Document 4).

Japanese Patent Laid-Open No. 11-104127 JP-A-11-104128 JP 7-275240 A Japanese Patent No. 3066944

  By the way, the two-dimensional type image sensor can be used very easily as a substitute for the conventional X-ray film because of its shape, but the acquisition price increases dramatically according to the size of the light receiving part. There is a problem and it is practically difficult to use a large size two-dimensional image sensor. Further, in tomographic imaging in which a subject is photographed and a tomographic image is generated from the photographed image, a large-size two-dimensional image sensor is used, and the subject is irradiated with an X-ray cone beam corresponding to the size. If this happens, there will also be a problem of exposure to the subject.

  On the other hand, especially in tomographic image capturing that generates tomographic images from a large number of images, comparison is made so that only unnecessary small parts near the region of interest of the subject are excluded from imaging. A configuration that uses a narrow X-ray cone beam and obtains an X-ray image with a two-dimensional image sensor having a size corresponding to the X-ray cone beam is advantageous in terms of cost and exposure. For that purpose, it is desirable to switch the image sensor of each size according to the shooting purpose, but in the above-mentioned conventional technology, this switching operation is not always easy and complicated. Met.

  An object of the present invention is to provide an X-ray imaging apparatus having a novel configuration capable of imaging at least two types of tomographic plane images by simple switching of the X-ray detection unit.

In order to solve the above problems, the X-ray imaging apparatus of the present invention has the following configuration.
A moving unit having a support unit provided with an X-ray generator and an X-ray detection unit so as to face each other with a subject interposed therebetween, and moving the X-ray generator and the X-ray detection unit by moving the support unit When,
X-ray imaging control means comprising imaging trajectory control means for operating the moving means and moving the X-ray generator and the X-ray detector along an imaging trajectory according to the type of imaging;
An X-ray imaging apparatus comprising an imaging type selection means for selecting an imaging type,
a) The X-ray generator can generate X-rays by selectively switching between an X-ray slit beam and an X-ray wide-area beam by irradiation field control means for switching the irradiation field shape of the irradiation X-rays.
b) The X-ray detection unit receives the X-ray image which has received the X-ray slit beam, and receives the first X-ray image sensor having a long and small width for capturing the X-ray image transmitted through the subject, and the X-ray wide-area beam. The second X-ray image sensor for capturing an X-ray image transmitted through the subject is provided on each of the two opposing surfaces of the casing, and the casing is horizontally inverted, whereby the first X-ray image sensor is provided. Either one of the X-ray image sensor and the second X-ray image sensor is set so as to be able to face the X-ray generator, and the first X-ray image sensor is used for taking a panoramic tomographic image, and The second X-ray image sensor is configured to be used for taking an X-ray CT image,
c) the support has a vertical axis of rotation;
d) The X-ray imaging control means is operated by the imaging trajectory control means,
When panoramic imaging is selected as the imaging type, the X-ray slit beam transmitted through the subject by horizontally rotating the support unit while moving the rotation axis of the support unit is transferred onto the first image sensor. When the CT imaging is selected as the imaging type, the X-ray wide area region that is transmitted through the subject with the rotation axis at the center of the region of interest specified as the diagnostic part of the subject. Controlling the beam to be detected on the second X-ray image sensor;
e) In the CT imaging, in addition to the CT imaging for controlling the X-ray wide-area beam so as to irradiate the entire region of interest while the irradiation field control means is imaging, the interest field control means is performing the interest during the imaging. Includes offset scan CT imaging that controls the X-ray broad-band beam to illuminate a portion of more than half of the area;
f) The minimum horizontal turning angle of the X-ray generator and the second X-ray image sensor in the CT imaging in the CT imaging in which the X-ray wide-area beam irradiates the entire region of interest during imaging is 180 °. And the minimum horizontal turning angle of the X-ray generator and the second X-ray image sensor in the offset scan CT imaging is set to one rotation.

  According to a second aspect of the present invention, there is provided the X-ray imaging apparatus according to the first aspect, wherein the imaging trajectory control means is opposite to each other across a predetermined tomographic plane intended by the X-ray generator and the X-ray detection unit. The second X-ray image sensor detects the linear X-ray wide-area beam that has passed through the predetermined tomographic plane when the linear tomographic plane image is moved and controlled. It is characterized by being performed in.

According to the present invention, a relatively low-price line-type image sensor can be used as the first X-ray image sensor, and only a narrow range around the region of interest needs to be captured when capturing a tomographic image. In the case of X-ray panoramic radiography, a two-dimensional image sensor having a small light receiving area can be used as the first X-ray image sensor. Therefore, it is advantageous in terms of cost. When CT imaging is performed by receiving X-rays from a wide-area beam, the second X-ray image sensor can be used to properly use the image sensor according to the imaging purpose.
Furthermore, a first X-ray image sensor (panoramic tomography sensor) and a second X-ray image sensor (CT imaging sensor) are provided on each of two opposing surfaces of a rectangular parallelepiped housing. Is rotated 180 degrees horizontally, so that either the first X-ray image sensor or the second X-ray image sensor can be selected and faced with the X-ray generator. The switching of the corresponding X-ray image sensor is easily performed without any inconvenience, and the efficiency of imaging medical care is improved.
In addition, since the rotation axis is vertical and the support means pivots horizontally around the rotation axis, the pan axis is moved during panoramic radiography, and CT imaging is performed with the rotation axis fixed, so that the patient can stand upright. It can shoot as it is, and does not take up space on the device.
In CT imaging, in addition to normal CT imaging for controlling the X-ray wide-area beam so as to irradiate the entire region of interest, the X-ray wide-area beam is controlled so as to irradiate a half or more of the region of interest. Since offset scan CT imaging is also possible, CT imaging of a wide area can be performed using an image sensor with a small detection surface. .
Further, since the X-ray generator can selectively switch between the X-ray slit beam and the X-ray wide-area beam by the irradiation field control means, X-rays corresponding to the imaging mode can be generated. The beam is appropriately generated, and the X exposure suppression control more than necessary for the subject is easily performed.

  Furthermore, according to the X-ray imaging apparatus of claim 2, the imaging trajectory control means moves the X-ray generator and the X-ray detection unit in opposite directions across a predetermined tomographic plane. Thus, the imaging of the linear tomographic plane image can be performed by detecting the X-ray wide-area beam that has passed through the predetermined tomographic plane with the second X-ray image sensor.

1 is a block diagram illustrating a schematic configuration of an X-ray imaging apparatus as an embodiment of the present invention. (A) (b) (c) is a schematic diagram explaining the mechanism of the X-ray generator used for the X-ray imaging apparatus of FIG. It is an external view explaining the example of the basic composition of the X-ray detector used for the X-ray imaging apparatus of FIG. (A) (b) is a figure which shows the example of the shape of the detection surface of a 1st image sensor and a 2nd image sensor, respectively. It is drawing which shows the envelope which the locus | trajectory of a X-ray slit beam draws at the time of panoramic tomographic plane image photography. (A) and (b) are plan views illustrating two types of imaging trajectories in which an X-ray generator and an X-ray detection unit move synchronously when imaging a linear tomographic plane image. It is a top view explaining the imaging | photography trajectory to which an X-ray generator and an X-ray detection part move synchronously when imaging | photography of an X-ray CT image. It is a perspective view which shows the more specific example of the X-ray imaging apparatus by this invention. It is a top view of the X-ray imaging apparatus which added the cephalometric image imaging means. It is a side view of the X-ray imaging apparatus which added the cephalo image imaging means. (A) (b) is sectional drawing which shows the structure of the X-ray generator used for an X-ray imaging apparatus, respectively, and the drive part perspective view of a primary slit. (A) (b) is a top view which respectively shows the locus | trajectory for normal X-ray CT imaging | photography, a locus | trajectory, and an offset scan CT imaging | photography.

  Hereinafter, an example of an X-ray imaging apparatus according to the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram illustrating a schematic configuration of the X-ray imaging apparatus M. FIG. 2 is a schematic diagram for explaining the mechanism of the X-ray generator 11 used in the X-ray imaging apparatus M. FIG. 3 is an external view for explaining an example of the basic configuration of the X-ray detector 12.

  As shown in FIG. 1, the X-ray imaging apparatus M includes a moving means including an X-ray generator 11 facing each other with an object O interposed therebetween, and an X-ray detector 12 having X-ray detectors 12a and 12b. 13 and an X-ray imaging control means 14 for controlling the X-ray generator 11, the X-ray detection unit 12, and the moving means 13.

  The X-ray generator 11 is an X-ray tube 11a that generates X-rays by tube current or tube voltage controlled by the X-ray imaging control means 14, and a collimator (not shown) for extracting X-rays emitted from the X-ray tube 11a. And primary slit plates 11b and 11b for restricting the X-ray irradiation range. Here, the X-ray tube 11a constitutes an X-ray source, and the collimator and the primary slit plate 11b constitute an irradiation field control means 11D.

  The primary slit plate 11b shown in FIG. 2A is vertically long (about 5: 1 to 100: 1, preferably 10: 1 to 50: 1, more preferably 15: 1) to the X-ray shielding plate. ˜30: 1) is formed, and the X-ray generated in the X-ray tube 11a is restricted in the irradiation range by the narrow groove 11c, and is long and narrow. The gap beam B is irradiated toward the subject O. The shape of the irradiation field orthogonal to the traveling direction of the X-ray slit beam may be any shape, such as a rectangle, an ellipse, or a rectangle with rounded corners. This can be done by changing the shape of the narrow groove 11c. realizable.

  On the other hand, the primary slit plate 11b shown in FIG. 2B has a rectangular gap 11d (an aspect ratio of 1: 0.5 to 1: 1.5, preferably 1: 0) that is close to a square by an X-ray shielding plate. X-rays generated in the X-ray tube 11a are limited in the irradiation range by the rectangular gap 11d and have a predetermined spread. As shown in FIG.

  An X-ray cone beam can be used as the X-ray wide-area beam. The shape of the irradiation field orthogonal to the traveling direction of the X-ray wide-area beam may be circular, elliptical, square, or octagonal. That is, the X-ray wide-area beam can have various shapes such as a cone, a quadrangular pyramid, and an octagonal pyramid. This can be realized by changing the shape of the rectangular gap 11d.

  Therefore, in the X-ray generator 11 adopting the irradiation field control means 11D comprising the primary slit plate 11b shown in FIGS. 2A and 2B, the X-ray imaging control means 14 causes the irradiation field control means 11D to be changed. By controlling one of the two primary slit plates 11b and 11b shown in FIGS. 2 (a) and 2 (b), the X-ray slit beam B or X-ray corresponding to the selected gap is selected. A wide beam BB can be selectively switched and generated.

  In addition, the primary slit plate 11b shown in FIG. 2C is obtained by forming both the narrow groove-shaped gap 11c and the rectangular gap 11d on a single X-ray shielding plate. In the X-ray generator 11 that employs the irradiation field control means 11D composed of the slit plate 11b, the X-ray imaging control means 14 drives an actuator (not shown) of the irradiation field control means 11D and the like of the X-ray tube 11a. By sliding the primary slit plate 11b arranged in the forward direction to the left and right, the X-ray slit beam B or the X-ray wide-area beam BB can be selectively switched and generated.

  The X-ray detection unit 12 includes a first image sensor 12a and a second image sensor 12b corresponding to the X-ray slit beam B and the X-ray wide-area beam BB irradiated by the X-ray generator 11, respectively. The first image sensor 12a is a CCD image sensor having a vertically long light receiving portion corresponding to the X-ray slit beam B, and the second image sensor 12b is a two-dimensional light having a rectangular light receiving portion corresponding to the X-ray wide-area beam BB. A CMOS image sensor of the type is preferable. However, the present invention is not limited to this, and both may be a CCD image sensor or a CMOS image sensor.

That is, in the present invention, the configuration of the X-ray image sensor is not limited, and the first and second image sensors 12a and 12b are CCD sensors, MOS sensors, CMOS sensors, TFT sensors, FT sensors, X-rays, or the like. It is configured by any one of a solid-state imaging device, XII (X-ray image intensifier), and MIS type sensor. The MIS sensor is a metal having a structure composed of a metal, an insulating layer, and a semiconductor layer described in Patent Document 4.
It means an Insulator Semiconductor sensor.

  In the above description, a rectangular light-receiving unit sensor is used as the second image sensor. However, the present invention is not limited to this, and the main point is a two-dimensional image sensor having a spread corresponding to the X-ray wide-area beam BB. There may be various shapes such as a circle, an ellipse, an octagon, and the like.

  In the X-ray detection unit 12 shown in FIG. 3, a first image sensor 12a and a second image sensor 12b are provided on each of two opposing surfaces of a rectangular parallelepiped casing 12c, and X-ray imaging is performed. By driving an actuator or the like (not shown) by the control means 14 and rotating the housing 12c horizontally by 180 degrees, either the first image sensor 12a or the second image sensor 12b is selected, It faces the X-ray generator 11.

  4A and 4B show examples of the shapes of the detection surface S1 of the first image sensor 12a and the detection surface S2 of the second image sensor 12b. The example of FIG. 4A is an example in which the detection surface S1 and the detection surface S2 are rectangular or rectangular, but for example, a shape with rounded four corners of a rectangle as shown in FIG. is there.

  Here, the maximum vertical dimension of the detection surface S1 is W1f, the maximum vertical dimension of the detection surface S2 is W1g, the maximum horizontal dimension of the detection surface S1 is W2f, and the maximum horizontal dimension of the detection surface S2 is W1f. If the significant dimension is W2g, it can be set so that W1f> W1g and W2f <W2g. These vertical and horizontal dimensions can also be set from a ratio, and may be set to have a relationship of W1f / W2f> W1g / W2g. For example, if W2f is 1, W1f may be set at a ratio of 3-30, and if W2g is 1, W1g may be set at a ratio of 0.3-2.

  More specifically, W1f is conventionally set to about 150 mm or 150 mm ± 30 mm, which is most suitable for panoramic tomographic plane images, and W2f is set to about 10 mm or about 10 mm ± 5 mm, which is also suitable for clear imaging of the target tomography. W1g is about 120 mm or 120 mm ± 30 mm suitable for imaging only several dentitions or ear stapes, and W2g is also used to image only several dentitions or ear stapes. It may be set to about 120 mm or 120 mm ± 30 mm suitable for.

  By setting the slit, the shape of the irradiation field of the X-ray slit beam on the detection surface S1 is formed into a shape suitable for the detection surface S1, and the irradiation field of the X-ray wide-area beam on the detection surface S2 is formed. If the shape is formed in a shape suitable for the detection surface S2, the X-ray beam can be irradiated without waste.

  It should be noted that the horizontal width of all the second image sensors 12b of the present invention is set to a region of interest S required in a specific medical field such as dentistry or otolaryngology (for example, only the dental arch or a specific part in the dental row). And the size of the irradiation field of the wide-area beam BB irradiated to the second image sensor 12b is also set to the second width of the second image sensor 12b. If the size of the image sensor 12b is set to a necessary size, it is possible to irradiate a wide-area beam toward only the region of interest, thereby reducing the amount of exposure.

  Similarly, the vertical width of the second image sensor 12b is set to a size corresponding to the vertical width of the region of interest S, and the irradiation field of the wide-area beam BB irradiated to the second image sensor 12b is large. Alternatively, the size may be set as much as necessary for the second image sensor 12b.

  The moving means 13 holds the support portion 13a having the X-ray generator 11 and the X-ray detection portion 12, and the rotation axis A of the support portion 13a so as to freely rotate and hold the rotation axis A. An axis moving table 13b that can move the axis A along a horizontal plane and a holding means 13c that positions the subject O are configured. For the turning movement of the support part 13a and the horizontal movement of the rotation axis of the support part 13a, independent stepping motors controlled by the X-ray imaging control means 14 are used as drive sources. Further, the holding means 13c may be moved up and down by a similar stepping motor.

  The irradiation angle of the X fine slit beam B or the X-ray wide-area beam BB is basically parallel to the horizontal plane, but is not limited to this. That is, a configuration in which the subject O is irradiated with X-rays at an irradiation angle oblique to the horizontal plane is also conceivable. This is because metal parts such as dentures have a large artifact in X-ray photography, and there are cases where it is desired to take pictures while avoiding metal parts. This is a problem particularly in X-ray CT image capturing. Therefore, in that case, it is desirable to irradiate the subject O with the X fine gap beam B or the X-ray wide-area beam BB obliquely so as to avoid the metal portion.

  The X-ray imaging control unit 14 includes a motor control unit 13d having a stepping motor that drives the moving unit 13, a display unit 15a that displays information such as an X-ray image on a monitor television, and an operation unit that receives operations such as a keyboard and a mouse. 15b etc. are connected, and as a functional element, the tube current and tube voltage of the X-ray tube 11a of the X-ray generator 11 are controlled, and further, the primary slit plate 11b of the irradiation field control means 11D is operated, X-ray generation control means 14a for selectively switching between the X-ray slit beam B and the X-ray wide-area beam BB and either the first image sensor 12a or the second image sensor 12b generate X-rays. The image sensor control means 14b that acquires the data of the X-ray image transmitted through the object O and the motor control unit 13d are operated by being in contact with the device 11 and controlled by the motor control unit 13d. An imaging trajectory control means 14c for operating the means 13 to move the X-ray generator 11 and the X-ray detector 12 along an imaging trajectory corresponding to the type of imaging, and a transmission image from the acquired X-ray image data And image generation means 14d for generating a tomographic image.

  The display unit 15a and the operation unit 15b display a wide range image of the subject O and an image taken prior to the target tomography, and a region of interest S that is a tomographic plane or a diagnostic part to be tomographed inside the subject O. Further, for the region of interest S, the imaging type selection means 15 for selecting the imaging type of the tomographic image is configured.

  Next, selection of an imaging type and imaging of a tomographic plane image, which are basic operations of the X-ray imaging apparatus M, will be described in order. The operator can determine the region of interest S by an operation such as mouse click after moving the cursor to the region of interest S such as a tomographic plane or a diagnostic part using the mouse of the operation unit 15b, for example. Then, if an imaging type of a tomographic image captured for the region of interest S is selected by an operation such as pressing a predetermined key, tomographic imaging is started. As the tomographic plane image, a linear tomographic plane image, an X-ray CT image, a panoramic tomographic plane image, or the like can be selected.

  For tomographic plane imaging, for example, X-ray CT images and linear tomographic plane images can be captured while the X-ray generator 11 and the X-ray detector 12 are moved synchronously along a predetermined imaging trajectory. The X-ray generator 11 irradiates a wide X-ray beam BB, and the second image sensor 12b of the X-ray detection unit 12 takes a plurality of transmission images of the subject O as a frame image having a predetermined spread. After obtaining a plurality of transmission images corresponding to the positions of the imaging trajectories, a tomographic plane image of the region of interest S is obtained by image processing that combines or calculates them. Further, for example, in the case of taking a panoramic tomographic plane image, from the state shown in FIG. 3, the housing 12c is horizontally rotated 180 degrees so that the first image sensor 12a faces the X-ray generator 11, and X-rays are obtained. A transmission image obtained by irradiating the X-ray slit beam B from the generator 11 toward the first image sensor 12a is subjected to image processing by calculation to obtain a panoramic tomographic plane image.

  In this imaging, the imaging trajectory control means 14c reads the trajectory data stored in an imaging trajectory memory (not shown), and controls the moving means 13 through the motor control section 13d, whereby the X-ray generator 11 and the X-ray detection section. 12 are moved synchronously along the imaging trajectory for tomographic image imaging defined by the read trajectory data. Further, when the X-ray generation control means 14a reaches the position of the predetermined imaging trajectory, the X-ray generation beam 11 is transmitted from the X-ray generator 11 according to the intensity data stored in the irradiation intensity memory (not shown), that is, the profile. The image sensor control unit 14b receives X-rays transmitted through the region of interest S by the second image sensor 12b and the first image sensor 12a, and generates a transmission image while irradiating the region of interest S to O. It is made to transmit to the means 14d. When this imaging is completed, the image generation unit 14d can perform a predetermined process on the transmitted transmission image and generate a tomographic plane image of the region of interest S. The profile may be selected according to the sex or physique of the subject who is the subject O, or the second image sensor 12b or the first image sensor 12a receives the light and measures regardless of the profile. The X-ray intensity may be fed back and controlled.

  The panoramic tomographic plane image referred to in the present application is a tomographic image of teeth and jaws along the dental arch, and a panoramic tomographic plane image of the subject O is obtained by imaging according to such an imaging trajectory.

  As shown in FIG. 5, the trajectory at the time of panoramic tomographic image imaging is a substantially triangular shape that is subject to left and right with the vertex of the X-ray slit beam projecting toward the front tooth portion of the dental arch as a boundary. It is possible to adopt a configuration of a known panoramic X-ray imaging apparatus that moves the X-ray detector and the X-ray generator so as to draw an envelope trajectory.

  FIG. 5 shows how the trajectory of the X-ray slit beam B irradiated from the X-ray generator 11 toward the first image sensor 12a draws an envelope EN. That is, the locus of the X-ray slit beam B becomes the envelope EN by the combination of the turning of the X-ray generator 11 and the first image sensor 12a by the turning of the support portion 13a and the movement of the rotation axis A of the support portion 13a. Forming.

  Furthermore, an example of an imaging trajectory when a linear tomographic image or an X-ray CT image is acquired as a tomographic image will be described with reference to the drawings. It is also possible to take a panoramic tomographic image as a tomographic image.

  In taking a linear tomographic image, the subject O is always irradiated with an X-ray wide-area beam BB with the projection angle changed around only the target predetermined tomographic surface, and only the predetermined tomographic surface is emphasized. As described above, a tomographic image is obtained by dispersing image information of X-rays transmitted through a part other than a predetermined tomographic plane. The linear tomographic plane referred to in the present application is the above-described predetermined tomographic plane that is photographed at the center. The imaging position includes a plurality of points with different projection angles on the imaging trajectory. It is also possible to take a linear tomographic image using the X-ray slit beam B.

  Further, X-ray CT images are taken by turning the X-ray wide-area beam BB at an angle of at least 180 ° around the region of interest S so that the region of interest S set on the subject O is always included. A tomographic plane image in an arbitrary direction is obtained by calculating a back projection image for a large number of transmission images photographed at each predetermined turning angle.

  The panoramic tomographic image is acquired by transmitting the X-ray slit beam B perpendicularly toward the dental arch that is the region of interest S set on the subject O and subdividing the dental arch. The images are sequentially overlapped or synthesized to obtain a single panoramic tomographic image, but microscopically, images taken from different angles are superimposed or synthesized. That is, in the panoramic tomographic plane image, the images acquired with the X-ray slit beam are sequentially superimposed or synthesized so that the cross section of the dental arch is emphasized.

  FIG. 6A is a plan view illustrating an imaging trajectory in which the X-ray generator 11 and the X-ray detection unit 12 move synchronously when imaging a linear tomographic image as a tomographic image. Here, a tomographic plane is set as the region of interest S for the subject O. FIG. 6B is different from FIG. 6A in the trajectory in which the X-ray generator 11 and the X-ray detector 12 move. That is, in the locus of FIG. 6A, the X-ray generator 11 and the X-ray detection unit 12 linearly move in opposite directions with respect to the predetermined predetermined tomographic plane indicated by the region of interest S in the figure. On the other hand, the X-ray generator 11 and the X-ray detector 12 are moved in arcs in opposite directions along the trajectory of FIG.

  In this case, the imaging trajectory control means 14c controls the X-ray generator 11 that irradiates the X-ray wide-area beam BB by controlling the moving means 13 so that the imaging trajectory heads from the position (p31) to the position (p33). The second image sensor 12b of the X-ray detector 12 is moved synchronously along the imaging trajectory from the position (q31) to the position (q33). A linear tomographic plane image can be synthesized by photographing according to such a photographing trajectory.

  For example, during imaging in accordance with the imaging trajectory, a transmission image can be sequentially acquired as a unit frame image, and the frame images can be combined with a linear tomographic image by superimposing only a desired tomographic part.

  In addition, for example, one linear tomographic image in which image data is accumulated as a single image can be acquired without obtaining a transmission image divided into a plurality of images during imaging according to the imaging trajectory. . This is based on the same principle as the conventional film photographing in which only the information on a specific linear tomographic plane is accumulated and emphasized because information is dispersed in portions other than the target linear tomographic plane.

  FIG. 7 is a plan view illustrating an imaging trajectory in which the X-ray generator 11 and the X-ray detector 12 move synchronously when an X-ray CT image is acquired as a tomographic plane image. Here, in the subject O, a cylindrical diagnostic region is set as the region of interest S.

  In this case, the imaging trajectory control means 14c controls the X-ray generator 11 adapted to irradiate the wide X-ray beam BB by controlling the moving means 13 so that the imaging trajectory heads from the position (p41) to the position (p43). The second image sensor 12b of the X-ray detector 12 is moved synchronously along the imaging trajectory from the position (q41) to the position (q43). The X-ray generator 11 moves from the position (p41) toward the position (p43), and the second image sensor 12b moves from the position (q41) toward the position (q43). In the region of interest S, the center of rotation with the image sensor 12b is rotated in a circle. The turning angle required for X-ray CT imaging is at least 180 °.

  A tomographic image can be synthesized with respect to an arbitrary cross section of the region of interest S by back projecting a transmission image obtained by imaging according to such an imaging trajectory by a known method.

  Next, a more specific example of the X-ray imaging apparatus M according to the present invention will be described with reference to the drawings. FIG. 8 shows a perspective view of the X-ray imaging apparatus M, and FIGS. 9 and 10 show a plan view and a side view of an example in which a cephalo image imaging means 18 is further added.

  The digital X-ray tomography apparatus M includes a moving means 13 having an X-ray generator 11 and an X-ray detector 12 and a main body frame 16 that firmly supports the moving means 13.

  The moving means 13 includes a support portion 13a to which the X-ray generator 11 and the X-ray detector 12 are fixed, and a rotation axis A in the Z direction on a plane XY perpendicular to the rotation axis A of the support portion 13a. It comprises an axis moving table 13b that horizontally moves (see FIG. 1). The axis moving table 13b is freely moved in the XY plane by a motor control unit 13d (see FIG. 1) having a stepping motor for driving the mechanism of the moving means 13, and an X-axis stepping motor and a Y-axis stepping motor. It has a shaft slide portion that constitutes a possible shaft moving mechanism, and the rotating shaft connected to the shaft slide portion can be moved horizontally, and the support portion 13a can be freely swung by the rotating shaft stepping motor. The moving means 13 can also move up and down along the main body frame 16 by a Z-axis stepping motor.

  The rotation axis direction of the support portion 13a is configured such that the patient who is the subject O is standing.

  The X-ray generator 10 is based on the basic configuration described with reference to FIG. 2 and includes an X-ray tube 11a having a fixed anode, a metal collimator, a narrow groove 11c for the X-ray slit beam B, and an X-ray wide area. It is composed of a primary slit plate 11b having a rectangular gap 11d for the beam BB, and selectively irradiates either the X-ray slit beam B or the X-ray wide-area beam BB. Here, the X-ray tube 11a constitutes an X-ray source, and the metal collimator and the primary slit plate 11b constitute an irradiation field control means 11D.

  FIG. 11 is an example of primary slit setting. When the type of imaging is switched, the X-ray irradiation field shape irradiated from the X-ray generator 11 and the light receiving shape on the X-ray detection unit 12 side are switched according to the imaging mode. An X-ray source X composed of an X-ray tube 11a is built in the housing including the X-ray generator 11, and the front surface of the housing facing the X-ray detector 12 has a primary slit SL1. A slit module SL including an adjustment mechanism for changing the shape of the line shielding plate and its primary slit is disposed. In the primary slit plate SL2 (corresponding to the primary slit plate 11b in FIG. 2) provided on the front side of the X-ray source X, as the primary slit SL1, a vertically long slit SL3 for panoramic tomographic plane imaging (FIG. 2). ), A rectangular slit SL4 for X-ray CT imaging (rectangular gap 11d in FIG. 2), and a long cephalometric imaging slit SL5 (narrow groove-like gap 11c in FIG. 2). When the type of photographing is changed, in the slit module SL, the drive motor 11D1 rotates the screw shaft 11D2 to guide the primary slit plate SL2 to the pulley 11D3 so that it can be moved left and right. A primary slit SL1 corresponding to the type of photographing is set.

  The X-ray detection unit 12 constituting the X-ray detection unit 12 is based on the basic configuration described with reference to FIG. 3, and is a fluorescent filter that converts X-rays into visible light, and an X-ray slit beam as the first image sensor 12a. A CCD image sensor having a vertically long light receiving portion corresponding to B, a CMOS image sensor having a short light receiving portion corresponding to the X-ray wide-area beam BB as the second image sensor 12b, and a secondary slit for shielding scattered X-rays The casing 12c, which is configured as a rectangular parallelepiped casing 12c with a built-in plate or the like, is attached to the support portion 13a so as to be rotatable around a vertical axis.

  On the side surface of the housing frame 17 provided on the main body frame 16, there are provided a display unit 15a and an operation unit 15b composed of an indicator lamp and an operation switch, and further a control unit comprising a CPU or the like is stored therein. Yes. A holding means 13c for positioning the subject O is also attached to the housing frame 17.

  What is seen in the center when viewed from the front of the holding means 13c is a chin rest 13g on which the patient places his chin. The chin rest 13g can be moved up and down or tilted and positioned according to the patient's body shape. By configuring the chin rest 13g to be movable in this manner, for example, it is possible to adjust the inclination of the irradiation line with respect to the horizontal plane for each imaging region such as the upper jaw and the lower jaw, and the upper jaw joint and the lower jaw tip located below In this way, it is possible to adjust so that a site separated vertically is positioned in the center of the irradiation field.

  Here, the structure of the moving means 13 and the accommodation frame 17 will be described in detail. In the example of FIG. 8, the axis moving table 13b is displaced up and down with respect to the main body frame 16 in accordance with the patient's physique. The shaft moving table 13b and the housing frame 17 are integrally formed. Therefore, the X-ray generator 11 and the X-ray detector 12 are moved up and down together with the housing frame 17 and the holding means 13c.

  However, the housing frame 17, the X-ray generator 11, and the shaft moving table 13 b that accompanies the raising and lowering of the X-ray detector 12 are configured separately, and each is independently displaced with respect to the body frame 16. It doesn't matter if you do. Moreover, you may comprise so that the X-ray generator 11 may be displaced with respect to the accommodating frame 17 thru | or the holding means 13c. The above-mentioned Patent Document 3 relating to the application of the present applicant describes an X-ray generator for an example in which the above-described housing frame 17 and the shaft moving base 13b are configured separately, or for the housing frame 17 or the holding means 13c. An example in which 11 is displaced is disclosed.

  In Patent Document 3, the portion corresponding to the housing frame 17 described above is referred to as a “patient frame”, and the portion corresponding to the axis moving table 13b is referred to as an “elevating body”. In addition, for example, by adjusting the tilt of the irradiation line with respect to the horizontal plane for each imaging region, the upper and lower jaw joints and the lower jaw tip located below can be irradiated well. It is to adjust so that it is located in the center of the field.

  The X-ray generator 11 is displaced with respect to the structure in which the chin rest 13g can be moved up and down or tilted, the structure in which the housing frame 17 and the shaft moving base 13b are separated, and the housing frame 17 or the holding means 13c. It may be possible to make finer adjustments by combining with the above-described configuration.

  The controller of this X-ray imaging apparatus controls the tube current and tube voltage of the X-ray tube 11a of the X-ray generator 11 as the X-ray imaging control means 14, and further operates the primary slit plate 11b to One of the X-ray generation control means 14a for selectively switching between the line slit beam B and the X-ray wide-area beam BB, the first image sensor 12a, and the second image sensor 12b is X-rays. An image sensor control unit 14b that acquires data of an X-ray image transmitted through the subject O is operated in a state of facing the generator 11, and a moving unit 13 is operated by controlling a motor control unit 13d. An imaging trajectory control means 14c for moving the ray generator 11 and the X-ray detector 12 along an imaging trajectory corresponding to the type of imaging, and a transmission image and a tomographic plane image are generated from the acquired X-ray image data Image generation hand To configure and 14d.

  The control unit can be connected to a display unit 15a for displaying information such as an X-ray image on a monitor television (not shown) and an operation unit 15b for receiving operations such as a keyboard and a mouse (not shown). By using the display unit 15a and the operation unit 15b, a tomographic plane to be tomographically imaged or a region of interest S to be diagnosed inside the subject O is selected, and a tomographic image type is selected for the region of interest S. An imaging type selection unit 15 is configured.

  The cephalometric image photographing means 18 has the same configuration as the mounting arm portion 18a connected to the rear part of the axis moving table 13b, the holding means 13c2 for positioning the subject O during cephalometric image photographing, and the X-ray detection part 12. Another X-ray detection unit 12A composed of a line detector is provided.

  Then, at the time of capturing the cephalo image, as shown in FIG. 9, the X-ray generator 11 is brought into a state where the X-ray generator 11 and another X-ray detection unit 12A including the X-ray detection unit face each other. It is possible to shoot cephalo images using.

  In the present invention, the movement of the X-ray generator and the X-ray image sensor (X-ray detection unit) relative to the subject O is a relative movement. Therefore, the X-ray detector and the X-ray image sensor may be moved while the subject is fixed, or the X-ray detector and the X-ray image sensor may be fixed and the subject may be moved relative thereto. As described above, in the present invention, the movements of the X-ray generator and the X-ray image sensor with respect to the subject are all defined by the relative movement described above.

  For example, when it is necessary to rotate (rotate) the X-ray generator and the X-ray image sensor relative to the subject when taking a tomographic image, the subject is fixed and the X-ray generator and the X-ray image are fixed. The sensor may be rotated, but the subject may be rotated or moved while the X-ray generator and the X-ray image sensor are fixed. Further, rotation or movement of the subject may be combined with turning of the X-ray generator and the X-ray image sensor. The same applies to operations other than turning (rotation).

  In the present application, the term “panoramic tomographic plane image” refers to an entire jaw panoramic tomographic plane image without particular distinction. In any tomographic image capturing, the object is preferably acquired from two directions. This is because the three-dimensional position of the region of interest can be grasped by acquiring from two directions.

  FIG. 12 is a plan view showing a locus of an X-ray beam for X-ray CT imaging, and shows a locus for offset scan CT imaging. At the time of offset scan CT imaging, the X-ray generator 11 and the X-ray detection unit 12 use the rotation axis A aligned with the center of the region of interest S as the axis of rotation, and the X-ray generator 11 and the region of interest. In a state where the second image sensor 12b is offset with respect to a straight line passing through S, the second image sensor 12b rotates synchronously for at least one rotation or more, and a portion of the region of interest S that is 1/2 or more of the second image sensor 12b is always projected.

  The idea of the present invention can also be applied to an X-ray imaging apparatus used for purposes other than medical use. That is, even for industrial use, there may be cases where imaging for nondestructive inspection is performed, and it is desirable to apply the idea of the present invention to an X-ray imaging apparatus for such use.

11 X-ray generator 11D Irradiation field control means 12 X-ray detection unit 12a First X-ray image sensor 12b Second X-ray image sensor 12c Case 14 X-ray imaging control means 15 Imaging type selection means B X-ray slit Beam BB X-ray wide-area beam M-ray imaging device O Subject

Claims (2)

A moving unit having a support unit provided with an X-ray generator and an X-ray detection unit so as to face each other with a subject interposed therebetween, and moving the X-ray generator and the X-ray detection unit by moving the support unit When,
X-ray imaging control means comprising imaging trajectory control means for operating the moving means and moving the X-ray generator and the X-ray detector along an imaging trajectory according to the type of imaging ;
An X-ray imaging apparatus comprising an imaging type selection means for selecting an imaging type,
a) The X-ray generator can generate X-rays by selectively switching between an X-ray slit beam and an X-ray wide-area beam by irradiation field control means for switching the irradiation field shape of the irradiation X-rays.
b) The X-ray detection unit receives the X-ray image which has received the X-ray slit beam, and receives the first X-ray image sensor having a long and small width for capturing the X-ray image transmitted through the subject, and the X-ray wide-area beam. , and a second 2 X-ray image sensor for capturing an X-ray image transmitted through the subject on each of two opposite sides of the casing, by inverting the casing horizontally, the first X Either one of the X-ray image sensor and the second X-ray image sensor is set so as to be able to face the X-ray generator, and the first X-ray image sensor is used for taking a panoramic tomographic image, and The second X-ray image sensor is configured to be used for taking an X-ray CT image ,
c) the support has a vertical axis of rotation;
d) The X-ray imaging control means is operated by the imaging trajectory control means,
When panoramic imaging is selected as the imaging type, the X-ray slit beam transmitted through the subject by horizontally rotating the support unit while moving the rotation axis of the support unit is transferred onto the first image sensor. When the CT imaging is selected as the imaging type, the X-ray wide area region that is transmitted through the subject with the rotation axis at the center of the region of interest specified as the diagnostic part of the subject. Controlling the beam to be detected on the second X-ray image sensor;
e) In the CT imaging, in addition to the CT imaging for controlling the X-ray wide-area beam so as to irradiate the entire region of interest while the irradiation field control means is imaging, the interest field control means is performing the interest during the imaging. Includes offset scan CT imaging that controls the X-ray broad-band beam to illuminate a portion of more than half of the area;
f) The minimum horizontal turning angle of the X-ray generator and the second X-ray image sensor in the CT imaging in which the X-ray wide-area beam irradiates the entire region of interest during imaging is set to 180 °, An X-ray imaging apparatus, wherein a minimum horizontal turning angle of the X-ray generator and the second X-ray image sensor in the offset scan CT imaging is set to one rotation .
The imaging trajectory control means controls the X-ray generator and the X-ray detection unit to move in the opposite directions with respect to a predetermined tomographic plane and captures a linear tomographic plane image, and The X-ray imaging apparatus according to claim 1 , wherein the tomographic image is captured by the second X-ray image sensor detecting the X-ray wide-area beam that has passed through the predetermined tomographic plane. .

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