JP2019063040A - X-ray imaging apparatus, and image processing method in x-ray imaging - Google Patents

Abstract

To enable a depth side of a tooth row to be visually observed easily, and reduce a labor load on a dentist while reducing a load on a patient receiving a treatment.SOLUTION: In an X-ray panoramic imaging device (11), the rotation of a pair of an X-ray generator (31, 31A) and a detector (32) is controlled, and the oral cavity part of a subject (P) is scanned by an X-ray while the mouth of the oral cavity part is kept open. An X-ray image (e.g., a panoramic image) is generated based on an electric signal output from the detector. The imaging device includes an optical camera (91) arranged at a portion of a rotation movement mechanism (24) for rotating the X-ray generator and the detector, which is capable of imaging a color optical image at a fixed rate, means (S51) for creating a color optical image putting the whole tooth row inside the oral cavity part in a visual field from the optical image captured by the optical camera, and means (S53, S55, and S56) for creating a fusion image by causing the X-ray image and the color optical image to correspond to each other positionally, and be subjected to fusion treatment.SELECTED DRAWING: Figure 10

Description

  The present invention relates to an X-ray imaging apparatus for obtaining an X-ray image of a subject from X-ray transmission data collected by irradiating the subject with X-rays, and an image processing method in X-ray imaging, in particular In addition to the X-ray image, an optical image of the subject is acquired, and the X-ray image and the optical image are displayed so as to overlap each other, a so-called X-ray imaging apparatus for obtaining a fused image, and image processing in X-ray imaging On the way.

  Conventionally, X-ray imaging apparatuses such as panoramic imaging apparatuses and dental X-ray CT apparatuses are often used in dental care and the like. Thereby, an X-ray panoramic image and an X-ray CT image of the oral cavity can be obtained. By observing this image, it is possible to interpret the internal condition of the teeth and gums.

  In this type of X-ray imaging apparatus, while moving a pair of an X-ray generator and a detector around a subject, the X-ray generator is generally spaced at constant intervals during movement. Radiation toward the subject. Furthermore, this X-ray imaging apparatus collects X-rays transmitted through the subject with a detector, and reconstructs an X-ray image by tomosynthesis based on the X-ray transmission data obtained by the acquisition, It is configured to be reconfigured with a configuration algorithm.

  In such an X-ray imaging apparatus, one example of a technique for superposing and displaying the X-ray image generated as described above and the optical image of the body surface of the subject, a so-called technique for generating and displaying a fusion image It is known from U.S. Pat. Specifically, according to Patent Document 1, a video camera for capturing a body surface visible moving image of a patient, and second information for extracting position information of each part of the patient in a three-dimensional space based on an image output of the video camera X-ray image control means for controlling an X-ray moving image of a patient in real time based on the outputs of the three-dimensional conversion means and the second extraction means, and the patient's output from the X-ray image control means Image synthesizing means for synthesizing X-ray moving image data and body surface visible moving image data of a patient output from the video camera; and synthetic image display means for displaying a patient moving image synthesized by the image synthesizing means Have.

  As another example, a dental computed tomography (CT) apparatus described in Patent Document 2 is shown. The apparatus comprises an X-ray imaging means, at least one color camera for taking pictures of the patient's face located at the imaging station of the apparatus from a plurality of different directions, and a face of the patient located at the imaging station. A means operatively connected to at least one laser or corresponding illumination structure and at least one color camera, mounted to send light patterns to a plurality of different positions, located at the imaging station Means for creating a virtual three-dimensional surface model from light pattern information sent to different positions of the patient's face, image information of the face detected by at least one color camera, and the patient's face And means for combining with the surface model to create a virtual three-dimensional texture model of the patient's face.

  Further, Patent Document 3 exemplifies a dental care system. According to this system, X-ray output means for outputting X-rays toward the inside of the cavity, Visualization imaging means for visualizing and imaging X-rays after the X-rays outputted by the X-ray output means have passed through the living body And an X-ray image captured by the visualization imaging means, and a display means for displaying or displaying the actual image corresponding to the imaging region.

  As described above, Patent Documents 1 to 3 describe that a camera image and an X-ray image are fused and presented.

Japanese Patent Application Laid-Open No. 2002-153458 (claim 6 etc.) Special table 2013-518649 (such as abstracts) Unexamined-Japanese-Patent No. 2012-157683 (Claim 7 etc.)

  For example, in order to detect subtle changes such as whether or not periodontal disease is caused and how it is progressing, not only the condition of the root portion inside the gums which can be judged from X-ray panoramic images or X-ray CT images It is important to look at the condition of the teeth and gums, in particular the change in color of the gums. In the conventional case, however, if there is a suspicious portion in the X-ray image, it is necessary to visually confirm the condition of the teeth and gums. The reverse is also the same. That is, the dentist needs the interpretation of the X-ray panoramic image and the state confirmation by visual observation (including the dental mirror), and the burden on the dentist for the interpretation is large. In addition, the burden on the patient is increased, for example, the time for diagnosis and treatment is increased and the time for opening the mouth is increased.

  Therefore, the present invention has been made in view of the situation encountered when using the above-mentioned conventional X-ray imaging apparatus, and in particular, the lesion of the oral cavity (the occurrence of periodontitis and its progress state) When making a diagnosis, it is possible to easily view the back of the dentition and to reduce the burden on the dentist and to reduce the burden on the patient when receiving treatment, and It aims at providing the image processing method of the radiography.

  In order to achieve the above-mentioned object, according to an X-ray imaging apparatus according to an aspect of the present invention, an X-ray generator for generating X-rays and X-rays generated from the X-ray generator are incident A detector capable of outputting an electrical signal of a digital amount corresponding to incident X-rays at a constant frame rate for each pixel, the X-ray generator and the detector are held, and the oral cavity of the subject is sandwiched therebetween In a state of facing each other, the X-ray generator and the pair of the detector are rotationally moved to move the pair of the X-ray generator and the detector so as to move around the oral cavity; An X-ray generator and a detector for controlling the oral cavity in a state where the mouth of the oral cavity is opened, scan command means for scanning according to the X-ray, and the scan command means for the scan command means The electrical signal output from the detector And an X-ray image generation unit for generating an X-ray image (for example, a panoramic image) based on the image, and a part of the rotational movement mechanism, and photographing a color optical image at a constant rate during rotational drive of the rotational movement mechanism An optical camera, color optical image forming means for forming a color optical image in a field of view of the entire dentition in the oral cavity from the optical image captured by the optical camera, the X-ray image, And a fusion image creating means for creating a fusion image in which the color optical images are caused to correspond to each other in position.

  As a result, the color optical image forming means obtains a color optical image in which the entire dentition of the oral cavity is included in the field of view. Therefore, when observing and treating the dentist, the state of teeth and gums as far as possible on the dentition You can know at once. This can reduce the time and effort such as the procedure of the dental mirror and the like, and reduce the burden of labor on the dentist and leads to the reduction of the burden on receiving the patient's treatment.

  Here, "a color optical image of the oral cavity part in view of the whole dentition in its inside" means "the whole of the gum and tooth line (dent line) having a standard horseshoe-shaped trajectory indicated by statistical data. A color image (also a real image seen by a doctor or the like) for optically photographing the surface. The size of the gums and dentition differs in adults and children. Since the shape of the dentition in the oral cavity, gums, missing teeth, etc. vary among individuals, such a definition is required in the present invention.

In the attached drawings,
FIG. 1 is a perspective view for explaining an outline of a panoramic image imaging apparatus as an X-ray imaging apparatus having a fusion function according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating the electrical configuration of the panoramic image capturing apparatus. FIG. 3 is a view showing a projection trajectory of the standard tomographic plane to the XY plane, which is set in the dentition. FIG. 4 is a diagram illustrating movement of a plane from a standard tomographic plane set on a dentition on the XY plane. FIG. 5 is a diagram for explaining the concept of gain used for a panoramic image. FIG. 6 is a diagram showing an example of a geometrical relationship between a color image captured by a camera for capturing a color optical image (real image) and a feature point of an object in a shooting space (real space) of a panoramic image shooting apparatus It is. FIG. 7 is a flow chart showing a part of processing for specifying the position on the shooting space (real space) of the feature point reflected in the color optical image from the geometrical relationship illustrated in FIG. FIG. 8 is a flowchart showing another part of the process for specifying the position on the shooting space (real space) of the feature point reflected in the color optical image from the geometrical relationship illustrated in FIG. is there. FIG. 9 is a flowchart showing still another part of the process for specifying the position on the imaging space (real space) of the feature point reflected in the color optical image from the geometrical relationship illustrated in FIG. It is. FIG. 10 is a diagram for explaining the flow of processing including the procedure of creating a fusion image in the panoramic image photographing apparatus together with the concept of an image. FIG. 11 is a photograph showing an example of an opening device to be inserted into the oral cavity of a subject (patient) at the time of imaging (this figure shows a state in which a therapeutic instrument is inserted). FIG. 12 is a photograph showing an example of the created fusion image. FIG. 13 is a view showing a modified example of the aperture.

  Hereinafter, with reference to the accompanying drawings, modes (embodiments) for carrying out the present invention will be described.

  First, an embodiment of a panoramic image photographing apparatus according to the present invention will be described with reference to FIGS.

  The panoramic image capturing apparatus scans X-rays to obtain a panoramic image of the oral cavity of a subject (patient) under a tomosynthesis method, and concurrently with the X-ray scan, the oral cavity of the subject And a configuration for obtaining a fusion image in which the captured panoramic image and the captured optical image are fused (integrated, integrated) with each other. That is, in the present embodiment, this panoramic image photographing apparatus is configured as a compound apparatus that can also obtain an optical image.

  The panoramic image is an image in which a curved oral cavity (gum, teeth, jaw bone, etc.) is reconstructed as a two-dimensional image. For this reason, an optical image is also created as a two-dimensional image obtained by photographing the oral cavity. The fusion image is a single image obtained by fusing a panoramic image and an optical image, as described later. Specific modes of this fusion include a mode in which an optical image is superimposed (overlapped) on a part of a panoramic image, an aspect in which a panoramic image is superimposed on (overlapping) a part of an optical image, and the like.

  This fusion image is implemented as parallel processing during scanning or post-processing after scanning. Therefore, the processing program for generating the fusion image may be integrated into the panoramic image photographing apparatus, or a processing apparatus such as a computer may be provided exclusively. In that case, it is desirable that the processing device is communicably connected to the panoramic image photographing device in a wired or wireless manner for receiving collected data by scanning.

  The purpose of obtaining this vision image is that the doctor can view the image in an X-ray transmission state and visually observe the state of the teeth and gums at the same time by looking at this image. Therefore, as an example, after reading a panoramic image and then observing this fusion image, the inside of the gums and root parts can be read and then the surface of the gum can be observed, and the two are compared. We can know the condition of the disease more multifacetedly. In particular, with regard to periodontal disease, there is no problem on X-ray transmission images (panoramic images), but its use is enormous, for example, the onset of diseases can be predicted from the color condition of the gum surface on an optical image.

  At this time, as will be described later, the dentist can operate the panoramic image capturing apparatus and perform a scan once to capture a panoramic image and a surface image, and obtain the fusion image. Therefore, as in the case of using a conventional panoramic image capturing apparatus, after looking at the panoramic image, the patient's mouth can be reopened, and the time and labor of visually observing the surfaces of teeth and gums with a dental mirror can be reduced. it can. This reduction in labor is a major factor in making diagnosis and treatment more efficient.

  From the viewpoint of visually observing the gums and the like with the naked eye, the optical image (surface image) makes it possible to photograph the entire dentition as much as possible.

  For this reason, the panoramic image photographing apparatus (11) according to the present embodiment has, as its basic configuration, an X-ray generator (31, 31A) for generating an X-ray and the X-ray as the basic configuration. A detector (32) capable of receiving an X-ray generated from a generator and outputting a digital signal corresponding to the incident X-ray at a constant frame rate for each pixel, the X-ray generator, and A rotary movement mechanism that holds the detector and rotates the X-ray generator and the pair of detectors so as to move around the oral cavity while holding the detector and facing each other across the oral cavity of the subject And (24). Further, the panoramic image photographing apparatus (11) opens the mouth of the oral cavity by controlling the X-ray generator and the detector while the rotational movement mechanism is rotating. And an X-ray image (for example, a panoramic image) based on the electric signal output from the detector in response to the scan instruction of the scan instruction unit. An optical camera which is disposed at a part of the X-ray image generation unit (53, 56 (S54)) to be generated and a part of the rotational movement mechanism, and can take color optical images at a constant rate during rotational drive of the rotational movement mechanism And (91). Further, this panoramic image photographing device (11) is a color optical image forming unit (a color optical image forming unit (field) which has a field of view of the entire dentition in the oral cavity from the optical image photographed by the optical camera. 53, 56 (S51, S52, S53) and a fusion image creation unit (56 (S55, S56)) for creating a fusion image in which the X-ray image and the color optical image are caused to correspond to each other in position. And.

  Here, "a color optical image of the above-mentioned oral cavity portion in which the entire dentition in the inside of the oral cavity is in view" means "the entire gum and tooth alignment (dental alignment) along a standard horseshoe trajectory indicated by statistical data. We say "color image to try to photograph the surface optically." The color optical image corresponds to a real image (surface image) of the surface of a tooth or a row of teeth viewed by a doctor or the like. The size of the gums and dentition differs in adults and children. For this reason, in this embodiment, since there are individual differences in the shape of the dentition in the oral cavity, gums, missing teeth, etc., such definition is required. Of course, in the case of patients with such a dextro-dental or buccal cavity out of the standard horseshoe trajectory, the physician will be treated individually, including the conventional method, each time.

  Hereinafter, the configuration, operation, and image processing of this composite type panoramic image photographing apparatus will be described.

  Of the panoramic image photographing apparatus according to the present embodiment, the configuration and operation relating to acquisition of a panoramic image are the same as Japanese Patent Application Laid-Open No. 2007-136163 (Japanese Patent Application No. 2006-284593; Japanese Patent No. 484886) already disclosed by the present applicant. is there. For this reason, in the present application, the configuration and operation relating to the acquisition of such a panoramic image will only be outlined. In this configuration and operation, a configuration for capturing an optical image (surface image) and a configuration for generating a fusion image are integrally incorporated.

  FIG. 1 shows an overview of a panoramic image photographing apparatus 1 according to this embodiment. As shown in the figure, the panoramic image photographing apparatus 1 comprises a case 11 for collecting, from a subject (patient) P, gray level original image data for panoramic image generation, for example, in a standing posture. A computer for controlling data collection performed by the housing 11, capturing the collected data to generate a panoramic image, and performing post-processing of the panoramic image interactively with the operator (doctor, technician) And a control / calculation device 12 composed of

  The housing 11 includes a stand unit 13 and a photographing unit 14 which can move up and down with respect to the stand unit 13. As shown in FIG. 1, for convenience of explanation, an orthogonal coordinate system of X, Y, and Z axes is set, in which the longitudinal direction of the stand portion 13 is the Z axis.

  The photographing unit 14 includes a substantially U-shaped vertical movement unit 23 and a rotation unit 24 rotatably supported by the vertical movement unit 23 when viewed from the side. The vertical movement unit 23 is movable in the Z-axis direction (longitudinal direction) over a predetermined range in the height direction via a drive mechanism (not shown) installed inside the column portion 22.

  The rotation unit 24 is suspended by the vertical movement unit 23, and is biased by the drive of the rotation movement mechanism 30 to rotate. The rotation unit 24 has a substantially U-shape as viewed from one side thereof in the use state, and the horizontal arm 24A rotates (parallelly) in the lateral direction, that is, in the XY plane, Left and right vertical arms (first vertical arm, second vertical arm) 24B and 24C extending downward (in the Z-axis direction) from both end portions in the longitudinal direction of the horizontal arm 24A are integrally provided. The rotation unit 24 is driven and operated under the control of the control / calculation unit 12. The rotational movement mechanism 30 is equipped with an encoder 30A that detects the rotational angle position.

  The X-ray tube 31 and the detector 32 are respectively equipped at tip portions of the left and right vertical arms 24B and 24C. The X-ray tube 31 is, for example, a rotating anode type X-ray tube.

  The detector 32 is, for example, an X-ray detection element formed of a semiconductor material such as CdTe (cadmium telluride) or a digital X-ray detector using an imaging plate. As an example, this detector 32 has an X-ray detection surface 32A (see FIG. 2) of 6.4 mm wide × 150 mm long, and the detection surface is composed of the above X-ray detection element, for example, 64 × 1500 pixels. It is formed. Thereby, for example, incident X-rays can be collected as image data of digital electrical quantities according to the quantity of the X-rays at a frame rate of 300 fps (one frame is, for example, 64 × 1500 pixels). Hereinafter, this collected data is called "frame data".

  Further, an optical camera 91 directed to the other vertical arm 24B facing the field of view is mounted in the vicinity (for example, near the upper side) of the detector 32 provided on the one vertical arm 24C. The optical camera 91 is, for example, a camera using a CMOS sensor, and as an example, the number of pixels is approximately 720 × 640, and the pixel size is approximately 50 μm × 50 μm. The optical camera 91 is for photographing in color the feature points of the dentition and the opening device of the oral cavity of the patient P, as described later. For this reason, the number of pixels and the pixel size may be another number of pixels or the pixel size as long as such photographing is possible. Of course, it may be an optical camera using a CCD or the like for the photographing pixel.

  Furthermore, the illumination device 92 for illuminating the illumination light toward the oral cavity of the patient P is provided in the one longitudinal arm 24C. This is to brighten the inside of the oral cavity and color capture a clearer optical image.

  FIG. 2 shows an electrical block diagram for control and processing of the panoramic image capturing apparatus.

  As shown in the figure, the X-ray tube 31 is connected to the control / calculation unit 12 via the high voltage generator 41 and the communication line 42, and the detector 32 is connected to the control / calculation unit 12 via the communication line 43. ing. The high voltage generator 41 is provided in the column portion 22, the vertical movement unit 23 or the rotation unit 24, and the control signal from the control / calculation unit 12 causes X-ray exposure to the X-ray tube 31 such as tube current and tube voltage. It is controlled according to the irradiation condition and the sequence of the irradiation timing. The X-ray tube 31 is provided with a slit 31A for limiting the field of view of the X-ray to be irradiated.

  The control / arithmetic unit 12 is, for example, a personal computer capable of storing a large amount of image data in order to handle a large amount of image data. That is, the control / arithmetic unit 12 includes, as its main components, the interfaces 51, 52, 62 communicably connected to each other via the internal bus 50, the buffer memory 53, the first image memory 54 (storage Means, a second image memory 55, an image processor 56, a controller (CPU) 57, and a D / A converter 59. A controller 58 is communicably connected to the controller 57, and the D / A converter 59 is connected to the monitor 60.

  Among these, the interfaces 51 and 52 are respectively connected to the high voltage generator 41, the detector 32, the optical camera 91 and the illumination device 92, and the interfaces of the controller 57 and the high voltage generator 41 and the detector 32 are connected. It mediates communication of control information and collected data exchanged between them. Another interface 62 connects the internal bus 50 to the communication line, and the controller 57 can communicate with an external device. As a result, the controller 57 can also capture an intraoral image captured by the intraoral X-ray imaging apparatus located outside, as necessary, and at the same time, the panoramic image captured by the present imaging apparatus and the focus optimization image based on that image. For example, it can be sent to an external server according to the DICOM (Digital Imaging and Communications in Medicine) standard.

  The buffer memory 53 temporarily stores the digital amount of frame data from the detector 32 received via the interface 52.

  Further, the image processor 56 is placed under the control of the controller 57, and generates (reconstructs) a panoramic image (X-ray image) of a standard tomographic plane along the patient's dentition, a tooth to be photographed from a color optical image Automatic detection of row feature points, creation of color optical images for vision, fusion (combination, combination, superposition) of panoramic images and color optical images automatically or interactively with the operator Have a function to A program for realizing this function is stored in advance in the ROM 61.

  In the present embodiment, the standard tomographic plane used for reconstruction of the panoramic image is provided as a tomographic plane selected from a plurality of standard tomographic planes for adults, children, etc. prepared in advance. This standard fault plane refers to a virtual curved fault plane (a fault plane which forms a horseshoe when viewed from the vertical direction) set from statistical data of the shape and size of human dentition. FIG. 3 exemplifies the selected standard cross section for adults. For this reason, the teeth of a subject having a standard shape and size are centered on this tomographic plane and aligned along the curved plane, so that the panoramic image of the standard tomographic plane itself is already the best focus image. However, in practice, the individual subject has a dentition that is entirely or locally offset from the normal tomographic plane.

  For this reason, when the focus of the site of interest is defocused in the panoramic image of the standard tomographic plane, which is the initial image to be first reconstructed, the optimal focus (focus is in focus using already acquired frame data) Image of) can be obtained. That is, there is no need to carry out the scan again. As described above, the panoramic image photographing apparatus 1 of this embodiment adopts the configuration described in Japanese Patent Application Laid-Open No. 2007-136163. Therefore, this second reconstruction is also obtained only by reconstruction in accordance with the collected frame data and the gain (described later) according to the new desired cross-sectional position in the imaging space. The new position may be a position obtained by shifting the focal plane itself to be focused from the position of the standard tomographic plane by a desired distance along the depth direction of the dentition as shown in FIG. It may be an oblique partial tomographic plane in which an area including the region of interest is moved in the depth direction of the dentition or rotated about one axis of the area on the image of the plane.

  Returning to FIG. 2, the frame data and image data processed or being processed by the image processor 56 are readably stored in the first image memory 54. For the first image memory 54, for example, a large-capacity recording medium (nonvolatile and readable / writable) such as a hard disk is used. In addition, the second image memory 55 is used to display the generated panoramic image data and / or post-processed panoramic image data. The image data stored in the second image memory 55 is called by the D / A converter 59 at a predetermined cycle, converted into an analog signal, and displayed on the screen of the monitor 60.

  The controller 57 controls the overall operation of the components of the apparatus, including a command to drive the optical camera 91 and the lighting device 92, in accordance with a program that carries out the entire control and processing stored in advance in the ROM 61. The program interactively receives operation information from the operator on predetermined matters. Therefore, as described later, the controller 57 generates a panoramic image of a standard tomographic plane, and parameters (gains) necessary for reconstruction that is responsible for the optimization of the focus of the panoramic image (that is, the process of further reducing blurring of the image). Or setting of shift & add amount), collection of frame data (scan), and interactive operation possible in consideration of the operation information of the operator output from the operation device 58. Note that, along with this scan, the optical camera 91 outputs the photographed color image data at a constant rate. Since the optical camera 91 is attached to the rotation unit 24 for X-ray scanning, it is not necessary to rotate the optical camera 91 itself around the subject.

  For this reason, as shown in FIG. 1, the patient places the jaw at the position of the chin rest 25 in the standing or sitting position and holds the mouthpiece 26 while inserting the opening device (see MS1 in FIG. 11). With the mouth open, the headrest 28 is pressed against the forehead. As a result, the position of the head (jaw) of the patient is fixed substantially at the center of the rotation space of the rotation unit 24. In this state, under the control of the controller 57, the rotation unit 24 rotates around the patient's head along the XY plane and / or along the oblique plane in the XY plane (see the arrow in FIG. 1). .

  During the rotation, under the control of the controller 57, the high voltage generator 41 generates a high voltage (designated tube voltage and tube current) for irradiation in a pulse mode of a predetermined cycle, for example. And the X-ray tube 31 is driven, for example, in a pulse mode. Thereby, pulsed X-rays are emitted from the X-ray tube 31 at a predetermined cycle. Of course, the X-ray tube 31 may be driven in a continuous mode so that X-rays are continuously irradiated.

  The X-rays thus irradiated pass through the patient's jaw (dental row) located at the imaging position and enter the incident surface 32A of the detector 32. As described above, the detector 32 detects incident X-rays at a very high frame rate (for example, 300 fps), and sequentially outputs the corresponding electrical quantity as frame data (for example, 64 × 1500 pixels). The frame data is temporarily stored in the buffer memory 53 via the communication line 43 and the interface 52 of the control / arithmetic unit 12. The temporarily stored frame data is then transferred to the first image memory 54 for storage.

  Therefore, the image processor 56 can generate a panoramic image along a standard tomographic plane along the dentition by reconstruction using the frame data stored in the first image memory 54. The image processor 56 can also generate a focus optimized image by reconstruction using frame data forming a region of interest (ROI) specified on the panoramic image. The panoramic image itself is also a cross-sectional image of the entire standard tomographic plane generated with the intention of optimizing the focus. However, in fact, due to the difference in the shape of the dentition of each individual subject, the standard tomographic plane alone has the least defocusing for each area (the best focus is within the range of the ability of the apparatus to exhibit). It is difficult to obtain an image, ie, the focus is optimized. For this reason, a reconstruction for obtaining a cross-sectional image showing the internal structure more clearly (with less blurring and in focus) based on the panoramic image of the standard tomographic surface (a cross-sectional image covering at least the entire dentition) Do. This post-processing reconstruction is usually targeted at a portion of the underlying panoramic image. In this embodiment, the cross-sectional image of this partial region is also considered as a focus optimization image.

  The generation of a focus-optimized image that includes a panoramic image that is the basis in this way involves a process called reconstruction. This reconstruction is performed by a process based on tomosynthesis method. This tomosynthesis method is known, for example, from the above-mentioned JP-A-2007-136163, JP-A-4-144548, etc. In a simple manner, plural pieces of frame data (two-dimensional mapping of pixel values) are supported in the scan direction. The process of shifting and superposing and adding each other along the direction This overlapping amount is called gain (or shift & add amount) as described above. By the shift-and-add process based on this gain, while the pixel values of the tomographic plane at the desired position in the dentition depth direction (see FIG. 4) are emphasized, the pixel values of the other tomographic planes are blurred. Thereby, a panoramic image of the tomographic plane at the desired position is obtained.

  Although the region of interest set on the panoramic image is usually specified on the panoramic image as a partial region forming a part of the panoramic image, it is also possible to set the entire panoramic image as the region of interest. Of course, a partial focus optimization image is generated when a doctor or the like wants it.

  The panoramic image and / or the partial focus optimized image are displayed on the monitor 60 in an appropriate manner, with the data stored in the first image memory 54.

  The photographing and interpretation of a panoramic image using the panoramic image photographing apparatus 1 are approximately as described above. The gain used to generate a panoramic image of a standard tomographic plane (this image is also a focus optimization image) and a partial focus optimization image of a designated area is, in this embodiment, described in JP-A-2007-136163 described above. As shown, it is set in advance by calibration using a phantom. This gain is a "quantity indicating the degree of superposition" of how much the frame data of each set is shifted and overlapped. When the gain is small, the degree of superposition is dense, and when the gain is large, the degree of superposition becomes coarse.

  An example of this gain will be described using the simplified model of FIG. In this model, a straight line connecting the X-ray tube 31 and the detector 32 to the object OB (dental row of the patient's jaw) D1 and D2 (respectively the X-ray tube and the detector at each point of the row) It is assumed that the relative ratio of the distance in the direction (depth direction) is kept constant and the relative movement speed is kept at a certain value. In this case, the amount (gain) of superposition of frame data in which the object OB is not blurred or blurred (that is, in focus) is determined.

  In other words, when scanning as described above, the focal plane (a continuous cross section in focus) can be determined by the moving speed and gain of the scanned X-ray relative to the object. Since this focal plane corresponds to the ratio of the distances D1 and D2, the focal plane is located in a plane translated from the detector 32 in each depth direction.

  Generally, the smaller the gain, the closer the focal position to the X-ray tube 31 in each depth direction Ddp, and the larger the gain, the farther the focal position is from the X-ray tube 31 in each depth direction Ddp. For this reason, using a phantom that quantitatively determines the distance between the X-ray tube 31 and the detector 32 in the depth direction orthogonal to the dentition at each position of the dentition, how much gain should be brought into focus The quantitative measurement (setting) is performed in advance for each position on the straight line along each depth direction.

  That is, the relationship between each position (each distance from the standard surface) and the gain is measured in advance using a phantom, and the relationship information is stored, for example, in the first image memory 54 as a look-up table LUT.

[Process of setting the position of the feature point of the object from the color optical image]
Next, referring to FIG. 6 to FIG. 8, from the photographed color optical image forming a part of the image processing executed by this panoramic image photographing device, the photographing space of the feature point of the tooth row to be photographed An outline of processing for setting a position on (three-dimensional real space) will be described.

  This process is performed by the image processor 56 immediately after the end of scanning or after data collection as post-scan post-processing.

FIG. 6 illustrates the geometrical relationship between the object OBJ which can be scanned by the panoramic image photographing apparatus 11 shown in FIG. 1 and the color optical images V ₁ and V ₂ photographed by the optical camera 91. In the figure, an absolute coordinate system xyz based on, for example, a fixed part of the panoramic image photographing device 11 is shown. The z-axis direction corresponds to the longitudinal direction of the device 11.

The two color optical images V ₁ and V ₂ are actually two-dimensional images. The object OBJ simulates the dentition in an abstract manner. The two color optical images V ₁ and V ₂ (hereinafter, the first optical image V ₁ and the second optical image V ₂ ) are calculated on the basis of the detection signal of the encoder 30A (see FIG. 1). It is an image of the position of the rotation angle θ = θ ₁ , θ ₂ of the unit 24. These rotation angle positions are predetermined two positions in the middle of the panoramic imaging scan accompanying the rotation of the rotation unit 24 and are determined in advance. Of course, this panoramic imaging scan is executed and processed in a three-dimensional space, but for ease of explanation, the schematic view of FIG. 6 is displayed in two dimensions viewed from the z-axis (vertical axis) direction.

Now, in the object OBJ, there is a feature area having a shape that is easily distinguishable from other parts, and it is assumed that the center point is the feature points OB ₁ , OB ₂ , OB ₃ and their feature points OB ₁ , OB ₂ and OB ₃ are extracted from the first and second optical images V ₁ and V ₂ . This extraction process is performed by default by the image processor 56 under control of the controller 57, as an example.

In the case of the principle diagram of feature point position setting shown in FIG. 6, the feature point OB _{1 of the} object OBJ is the first optical image V ₁ at the positions of the first and second optical images V ₁ and V _2. , OB ₂ is reflected. However, the third feature point OB ₃ of not reflected because not the first field of the optical image V _1. On the other hand, the second optical image _{V 2,} which is an example that all bleeds through the three feature points _{OB 1,} OB 2, OB _3. The distances between the first optical image V ₁ and the two feature points OB ₁ and OB ₂ are f ₁ and f ₂ , and the second optical image V 2 and the three feature points OB ₁ , OB ₂ and OB ₃ And the distances between them are f ₁ , f ₂ and f ₃ .

The optical camera 91 takes a number of color images at a constant rate in parallel with the X-ray scan, and sequentially stores the data thereof in the first image memory 54 via the buffer memory 53 in correspondence with the rotation angle θ ing. Therefore, when the process of setting the position of the feature point of the object is instructed, the image processor 56 detects the position of the rotation angles θ = θ ₁ and θ ₂ stored in the first image memory 54. The color image data is read out and processed as follows.

First, as shown in FIG. 7, the image processor 56 causes the monitor 60 to display the _first optical image V1 (step S10). Then, on the first optical image _{V 1,} automatically check and determine the position _P 1 _{B 2} there one that crowded-through eye feature point OB ₁ (step S11). The check and determination is made by a technique such as processing the shape of the feature point OB ₁ in pattern recognition. Then, on the first optical image _{V 1,} automatically check and determine the position _P 1 _{B 1} of the second feature point OB ₂ that crowded-through therein (step S12).

Next, the image processor 56 performs focus processing of the position P ₁ B ₂ of the _first feature point OB ₁ on the first optical image V ₁ using a known depth scan, and at the time of focusing, the distance _{f 1} determined stores (step S13). Furthermore, on the first optical image _{V 1,} 2 nd position _P 1 _{B 2} feature point OB ₂ similarly focus processing, and stores the determined distance _{f 2} at that time focusing (step S14) .

Similarly, the image processor 56, the second optical image _{V 2} is displayed on the monitor 60 (step S15). The positions of _two feature points OB ₁ and OB ₂ are confirmed on the second optical image V ₂ , and the positions P ₂ B ₁ and P ₂ B ₂ are confirmed and determined, respectively (steps S 16 and S 17). Furthermore, on the second optical image _{V 2,} to confirm and determine the position _P 2 _{B 3} of the third feature point OB ₃ (step S18). These confirmations / decisions are performed by methods such as threshold processing and pattern recognition of the shape of the feature point. The third feature point OB ₃ of, due to the presence in the field of view of the blind spot of the optical camera 91 when outputting a first optical image V _1, the first optical image V ₁ although not crowded-through write, Since it exists in the field of view of the optical camera 91 when the _second optical image V2 is output, it is reflected in the _second optical image V2.

Further, the image processor 56 first has the feature point OB ₁ focused by a known depth scan, and stores the determined distance f ₅ at that time focusing (step S19). The second focus similarly feature point OB _2, and stores the determined distance _{f 3} at that time focusing (step S20). Furthermore, the third focus similarly feature point OB ₃ of, for storing determined distance _{f 4} at that time focusing (step S21).

Then, as shown in FIG. 8, the image processor 56 again first optical image V ₁ on the monitor 60, is displayed, the image on the position of the first feature point OB ₁ that crowded-through there P ₁ B ₁ is calculated (step S31). Then, the first on the optical image _{V 1} that calculates a position _P 1 _{B 2} of the second feature point OB ₂ that crowded-through therein (step S32).

Further, the image processor 56 and the second optical image V ₂ again monitor 60 to display, on the image, it calculates the position P ₂ B ₁ of the first feature point OB ₁ that crowded-through therein ( Step S33). Similarly, on the second optical image _{V 2,} it calculates the position _P 2 _{B 2} of the second feature point OB ₂ (step S34). Furthermore, on the second optical image _{V 2,} it calculates the position _P 2 _{B 3} of the third feature point OB ₃ (S35).

Then, as shown in FIG. 9, of the first and second feature points, the position of the first feature point OB _{1 in} the two-dimensional space, that is, the position of one point on the surface of the object OBJ Is calculated from the geometrical relationship of the position P ₁ B ₂ , the distance f ₁ , the position P ₁ B ₂ , and the distance f ₅ obtained as described above, and stored (step S 41). Furthermore, the position of the second feature point OB _{2 in} the two-dimensional space is calculated from the geometrical relationship of the position P ₁ B ₁ , the distance f ₂ , the position P ₂ B ₂ , and the distance f ₃ obtained as described above. And store (step S42). Further, the third position on the two-dimensional space of the feature point OB ₃ of, calculated from the geometrical relationship between the position _P 2 _{B 2,} the distance _{f 4} obtained as described above, is stored (step S43).

Thereby, from the color image data photographed by the optical camera 91, the positions of the first, second and third feature points OB ₁ , OB ₂ and OB _{3 in} the real space, ie, the features of the surface of the object OBJ The position of the critical site (point) is determined. The position information on the real space is used to search for the corresponding position on the panoramic image as described later.

Therefore, similar to the _first , _second , and third feature points OB ₁ , OB ₂ , and OB ₃ described above, default information is previously stored as a feature site (point) found in the standard dentition of the patient's oral cavity. You should have as. Of course, those characteristic parts (points) may be interactively designated by the doctor each time.

Further, although the positions of the rotation angles captured by the optical camera 91 are _two positions of θ = θ ₁ and θ ₂ , the positions may be three or more in accordance with the number and positions of the feature points to be designated. For example, when viewed from the longitudinal direction (z-axis direction), a total of three positions may be provided: the front position of the front teeth side of the dentition and the two positions of the left and right rear tooth side surfaces. As these positions, rotation angle command values θ = θ ₁₁ , θ ₁₂ and θ ₁₃ (see FIG. 10 described later) may be set in default according to the detection signal of the encoder 30A. Since the optical camera 91 outputs its color image data at a constant frame rate during X-ray scanning, read out the color image data taken at the rotational angles θ = θ ₁₁ , θ ₁₂ and θ ₁₃ Thus, first, second and third optical images V ₁₁ , V ₁₂ and V ₁₃ are obtained (see FIG. 10).

  When each of the feature points designated on the object is reflected in the two optical images, the above-described focus scan in the depth direction, so-called depth scan, is not necessary.

[Example of creating a Fusion image]
An example of creation of a fusion image will be described.
The subject inserts an opener MSI illustrated in FIG. 11 to open the mouth, and receives an X-ray scan in a state in which the mouthpiece 26 is added at the center of the front teeth (first and second teeth). At this time, the optical imaging with the optical camera 91 is performed in parallel with the panoramic imaging with the X-ray scan as in the prior art. Note that FIG. 11 is merely given as an example of the opening device, and although a treatment device is used in the figure, there is no use of such a treatment device at the time of an X-ray scan.

FIG. 10 shows an outline of creation of this fusion image. In this case, the above-described depth scan is not used. Specifically, as shown in FIG. 10, a central portion of a specific shape formed by a break between the left and right 1 and 2 at the upper and lower sides of the standard dentition, and the left and right 6 teeth. The feature points M _1L , M _1R , M _L , and M _R can be set by default at the central portion of the specific surface shape formed by the outside. In this case, as shown in FIG. 10, the positions of the rotational angles θ = θ ₁₁ , θ ₁₂ and θ ₁₃ are specified to put these three feature images in the field of view and three optical images V ₁₁ , V ₁₂ and V You can get to get _thirteen . In this case, in the case of a standard dentition, the feature points M _1L , M _1R , M _L , and M _R are respectively reflected in the two optical images, so depth scanning is not necessary, and the position and length of the optical image are simply reduced. The position of the feature points M _1L , M _1R , M _L , and M _R in real space can be estimated from the relationship between the distance and the distance.

Specifically, the image processor 56 includes three first to third optical images V ₁₁ , V ₁₂ , in which four feature points M _1L , M _1R , M _L and M _R of the dentition are reflected. to Toshu the V ₁₃ (FIG. 10, step S51), the first to'll like from each of the foregoing third optical image _{V 11, V 12, V 13} , 4 one feature point _{M 1L, M 1R,} The positions of M _L and M _{R in} the real space are specified (step S 52). Next, the first to third optical images V ₁₁ , V ₁₂ , and V ₁₃ are connected based on the positions of the four feature points M _1L , M _1R , M _L , and M _R , and processing such as scaling is performed ( Combining process: step S53). Thus, one color optical image IM _OP is created.

On the other hand, the detector 32 is reconstructed X-ray panoramic image _{IM PA} from the frame data to be output (step S54). The X-ray panoramic image IM _PA, using the known techniques, once again cut from reconstructed panorama image oral region partially may be oral region image focused. Therefore, the image processor 56, whether the four characteristic points _M 1L of color optical image _{IM OP, M 1R, M L} , the position of the _{M R,} corresponding respectively where positions on the X-ray panoramic image _{IM PA,} described above A search is made on the basis of the real space position of the feature points M _1L , M _1R , M _L and M _R , that is, the information of the marker position of the dentition (step S 55). Thus, as shown in FIG. 10, on the X-ray panoramic image _{IM PA,} 4 one feature point _{M 1L, M 1R, M L} , the position _(point) corresponding to the _{M R M 1L ', M 1R} ', M _L ′ _′ and M _R ′ are set by the image processor 56.

Therefore, the image processor 56 matches the feature points M _1L , M _1R , M _L , and M _R and their corresponding points M _{1 L} ′, M _{1 R} ′, M _L ′ _′ , and M _R ′ with each other, and appropriately reduces them. while expanding, the color optical image of dentition on the panoramic image _{IM PA} (overlapped, synthesized) Fujon the _{IM OP} to, Fujon image _{IM FU} is created (step S56). Also, this step 56 causes the fusion image IM _FU to be displayed on the monitor 60.

An example of the fusion image IM _FU actually created by this flow is shown in FIG. In the fusion image IM _FU , an X-ray transmission image of a jawbone or the like is used as a background, and a color optical image IM _OP is superimposed on the dentition portion of the oral cavity.
The color optical image IM _OP can display the gums and the dentition as far as possible in the color, up to the far end. For this reason, the dentist can simply judge the color of the gums and the state of the periodontal disease near the root of the tooth or the like from the surface state in the vicinity of the back teeth, in addition to the jaw bone portion showing the internal structure in gray level by X-ray absorption. In this manner, a color optical image is created from the optical image captured by the optical camera, with the entire dentition in the oral cavity in a field of view. From this, the color optical image IM _OP not only reduces the time and effort for diagnosis but also diagnoses because the surface image similar to the visual image is displayed in color as far as possible to the back of the dentition as well as near the front teeth of the dentition. It is extremely effective as a tool. By observing the color optical image IM _OP , the dentist can re-fit the opening device MSI again as shown in FIG. 11 and greatly reduce the time and effort for reviewing the back teeth and their gums and the like with the dental mirror.

Also, lesion spread and structural abnormalities may be determined by comparing the panoramic image IM _PA and color optical image IM _OP.

  In the embodiment described above, the X-ray tube 31 and the slit 31A form the main part of the X-ray generator. The controller 57 corresponds to a scan command unit (command command unit) that commands an X-ray scan. The buffer memory 53 and the image processor 56 (the process S54 of the processor) constitute the main part of the X-ray image generation means (the generation unit). The buffer memory 53 and the image processor 56 (processes S51, S52, and S53 of the processor) form the main part of the color optical image forming means (the same generating unit). Further, the image processor 56 (the processes S55 and S56 of the same processor) form an essential part of the fusion image creating means (the same creating unit). Furthermore, the monitor 60 corresponds to display means.

[Modification]
A modification will be described based on FIG.
This variation relates to an example of an aperture for reflecting a color optical image to the deepest tooth of the dentition. The opening device M _OP shown in FIG. 13 has a mirror placed in the oral antrum (between the buccal mucosa and the dentition) as well as the cleft lip (upper and lower lip) and a color image including a reflection image of this mirror which is the opener M _OP configured as fit in the camera. As shown in FIG. 13 (A), the opening device has flaps 101U and 101L that interact with the upper and lower lips, flaps 101L and 101R that interact with the left and right mouth corners, and a resilient connection 101C that links these flaps. And In the figure, reference symbol MS2 indicates a lip.

Furthermore, the left and right flaps 101L and 101R are provided with mirrors 102L and 102R as shown in FIG. 13 (B). The mirrors 102L and 102R are located between the inside of the cheek FS and the back of the dentition when the opening device M _OP is fitted in the mouth of the subject, and the optically reflecting surface M _IR is against the dentition It is positioned at an angle.

  Thereby, a clearance SP is generated between the teeth and each of the mirrors 102L and 102R. For this reason, the reflected light of the illumination light reflected by each of the back teeth is reflected by the mirror 102L (102R) and travels outward from the opening portion. Therefore, mirror images of the mirrors 102L and 102R are captured together by the above-described optical camera 91. Therefore, by appropriately processing a color image captured including this mirror image, optical imaging can be reliably performed to the far side of the dentition, so that a color optical image can be obtained over the entire dentition, The usefulness of the fusion image will be further enhanced.

  Other modifications will be described.

  As another modification, not only the color optical image captured in parallel with the X-ray scan but also an intraoral photograph (color photograph) captured in the existing or separately may be fused to the panoramic image captured just now.

  Furthermore, information on plaster casts of dentition (three-dimensional form information, information on occlusion state) may be taken, and data based on the information may be fused to the panoramic image and / or color optical image described above.

  Furthermore, in the above-described embodiment, the vision image may of course be displayed alone, or may be displayed on the monitor 60 in a screen division method, for example, in combination with the captured panoramic image and color optical image. The images may be selected and displayed interactively with the operator.

Furthermore, as described above, the optical camera 91 for capturing a color optical image is not necessarily limited to the configuration that outputs a color image at a constant rate in parallel with the X-ray scan. For example, based on the angle information from the encoder 30A, the shutter of the optical camera 91 is turned on when reaching the position of the rotation angles θ = θ ₁₁ , θ ₁₂ and θ ₁₃ to obtain only three color images in total You may do so. Thereby, the memory capacity on the device side can be reduced.

  In the present embodiment, although the dentition of the subject P has been described as following the statistical standard trajectory, there is individual difference and the position of the feature point (marker) of the dentition set by default is the same. If it can not be used, the doctor may manually specify the feature point each time. Thus, it is possible to create a fusion image in accordance with the Fujon algorithm described in the embodiment.

  Furthermore, the setting of the feature points is not limited to the case of automatically recognizing from the color optical image of the dentition by processing such as pattern recognition, and is optically opaque to the frame portion FRM of the aperture unit MSI illustrated in FIG. A plurality of, for example, point-like lead markers, which are preferably colored and whose X-ray transmittance is different from that of the tissue of the oral cavity, may be provided. Since this marker is also reflected on the color optical image and the X-ray panoramic image, the fusion image can be created based on the position as described above.

  As described above, the present invention can be implemented in various modifications or in cooperation. Of course, the modifications other than those described above are the same unless they deviate from the spirit of the invention.

Claims (8)

X-ray generator (31, 31A) for generating X-rays;
A detector (32) capable of receiving an X-ray generated from the X-ray generator and outputting a digital signal corresponding to the incident X-ray at a constant frame rate for each pixel;
The X-ray generator and the pair of detectors are moved around the oral cavity while holding the X-ray generator and the detector and facing each other across the oral cavity of the subject. A rotational movement mechanism (24) that rotationally moves to
A scan command for controlling the X-ray generator and the detector to scan the oral cavity according to the X-ray while opening the mouth of the oral cavity while controlling the X-ray generator and the detector while the rotational movement mechanism is rotating. Means (57),
X-ray image generation means (53, 56 (S54)) for generating an X-ray image (for example, a panoramic image) based on the electric signal output from the detector in response to a scan instruction of the scan instruction means;
An optical camera (91) disposed at a part of the rotational movement mechanism and capable of photographing an optical image of a color at a constant rate during rotational driving of the rotational movement mechanism;
Color optical image forming means (53, 56 (S51, S52, S53)) for forming a color optical image from the optical image taken by the optical camera to the entire dentition in the oral cavity of the oral cavity. ,
Fusion image creation means (56 (S55, S56)) for creating a fusion image in which the X-ray image and the color optical image are caused to correspond to each other in position.
An X-ray imaging apparatus (11) comprising: The X-ray image generation means is configured to create a panoramic image of the oral cavity as the X-ray image,
The color optical image creating means is configured to create an oral cavity area image obtained by partially cutting out an oral cavity area image from the color optical image in the oral cavity portion,
The fusion image creation means is configured to create, as the fusion image, an image in which the oral region images are made to correspond to each other in a positional manner and superimposed on the panoramic image. X-ray imaging device. The X-ray image generation means is configured to create a panoramic image of the oral cavity as the X-ray image, and create an oral region image obtained by partially cutting out the oral region from the panoramic image or the panoramic image. And
The fusion image creation means is configured to create, as the fusion image, an image in which the oral region images partially cut out from the panoramic image are made to correspond in position with each other on the color optical image of the oral cavity. The X-ray imaging apparatus according to claim 1, characterized in that:   The fusion image creation means causes the X-ray image and the color optical image to be reflected in advance in the X-ray image and the feature points extracted from the color optical image respectively, or in the X-ray image and the color optical image. The X-ray imaging apparatus according to any one of claims 1 to 3, wherein the landmark images are configured to correspond to each other as the reference position and to create the fusion image.   The landmark is a physical part installed in a jig fitted for photographing in the oral cavity, and the feature point indicates a characteristic site including the dentition of the oral cavity extracted from the image. The X-ray imaging apparatus according to claim 4, which is a part. The color optical image creation means determines the depth to the surface of the dentition of the oral cavity at a plurality of positions of the optical camera rotated by the rotational movement mechanism, and the data representing the depth is obtained. Configured to extract the feature points indicating a feature of the dentition;
The X-ray image generation means is configured to extract a feature point corresponding to the feature point of the dentition from the X-ray image.
The X-ray imaging apparatus according to claim 4, wherein the fusion image creation unit is configured to fuse both images with the feature point as a reference position.   The X-ray imaging apparatus according to any one of claims 1 to 6, further comprising display means for displaying the vision image created by the vision image creation means. An X-ray generator for generating X-rays;
A detector capable of receiving an X-ray generated from the X-ray generator and outputting a digital signal corresponding to the incident X-ray at a constant frame rate for each pixel;
The X-ray generator and the pair of detectors are moved around the oral cavity while holding the X-ray generator and the detector and facing each other across the oral cavity of the subject. A rotational movement mechanism that rotationally moves to
A scan command unit that controls the X-ray generator and the detector to scan the oral cavity based on the X-ray while the rotational movement mechanism is rotating and moving;
An optical camera disposed at a part of the rotational movement mechanism and capable of photographing an optical image of a color at a constant rate during rotational driving of the rotational movement mechanism;
An image processing method in an X-ray imaging apparatus provided with
Generating an X-ray image based on the electrical signal output from the detector in response to the scan of the scan command means;
From the optical image taken by the optical camera, a color optical image is created in which the entire dentition in the interior of the oral cavity is in a field of view;
Creating a fusion image in which the X-ray image and the color optical image are brought into position correspondence with each other and fused;
An image processing method comprising: