JP2008086659A - Image processing method and panoramic image photographing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide cross-sectional images in a state with an optimized focus and less blurs with respect to the cross-sectional images of changed positions by three-dimensionally and freely changing the position of a cross-section to be observed in a tooth row with the use of panoramic image data for the digital portion of X-ray photographing, and also to redouble usefulness of three-dimensional position information held in the cross-sectional images. <P>SOLUTION: The panorama photographing device includes: means (54, 56, 57, 58) for generating the partial images of the respective optimum focuses in a plurality of designated partial areas of the panoramic image, based on the panoramic image data of the desired cross-section of an object; and means (54, 56, 57, 58, 60) having templates composed of a plurality of adhesion areas two-dimensionally arranged by prescribed format in connection with the attribute of the photographing part of the object, allowing the plurality of partial cross-sectional images to adhere onto the plurality of adhesion areas of the templates, and displaying and preserving the cross-sectional images. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a panoramic image photographing apparatus for photographing a panoramic image of a specific part of a subject, for example, a dentition, and an image processing method in the panoramic photographing, and particularly generates a panoramic image from digital X-ray transmission data. The present invention relates to an image processing method in which the panoramic image is read using a template, and a panoramic image photographing apparatus that performs the image processing method.

  With the recent changes in food culture and lifestyle, the number of people receiving dental treatments is increasing, and dental specialists frequently require regular dental examinations and early treatment. Has been recommended. In the case of treating teeth, in many cases, X-ray imaging is performed to check the state of teeth (dentition) and gums. Conventionally, this X-ray imaging has often obtained a local projection image of the gum part using an X-ray film. However, as an alternative method or a combination thereof, an X-ray CT scanner or a dedicated dentistry is used. A dental panoramic image photographing apparatus is used.

  The X-ray CT scanner simply applies a generalized CT imaging method to the imaging of the jaw part, and the resolution of the panoramic image along the dentition reconstructed from the acquired image by this scanner is so high In addition, the influence of metal artifacts is large, and the usage is limited to examining the entire dentition.

  On the other hand, the dental panoramic imaging apparatus positions the pair of the X-ray source and the X-ray detector so as to sandwich the jaw part of the subject, and moves the pair around the jaw part to collect the X-ray transmission data, A panoramic image along a predetermined cross section for the dentition is generated from this data. As an example of this dental panoramic image photographing apparatus, an apparatus described in the cited document 1 is known.

  This cited document 1 shows an example of a digital panoramic image photographing apparatus (name of the invention is “digital panoramic X-ray photographing apparatus”). The panoramic image photographing apparatus includes a turning drive unit that integrally turns an X-ray source and an X-ray image detection unit that are arranged to face each other with a subject interposed therebetween. The X-ray source includes an X-ray tube and a collimator that narrows the X-rays emitted from the X-ray tube into a slit beam shape. The X-ray image detection unit includes an X-ray detector such as an X-ray CCD sensor that outputs a digital amount of an electrical signal corresponding to the incident X-ray dose. Further, this panoramic image photographing apparatus sequentially stores image information collected by the X-ray detector as a frame image, and sequentially reads out the image information at a predetermined time interval from the storage means, Image processing means for adding the read image information while shifting the image information by a predetermined distance with respect to the direction in which the image moves, and forming a panoramic image having an arbitrary cross section according to the read interval of the image information and the shift amount. . Accordingly, a panoramic image of a cross section along the patient's dentition can be provided as a diagnostic image on a monitor such as a personal computer without using an X-ray film.

  However, in the case of this panoramic image photographing device, since photographing is performed so as to focus on a horseshoe-shaped standard surface (standard cross section) along a predetermined dentition as a standard, a cross section other than the standard surface is taken. If you want to see it again, you will need to take the picture again. Re-imaging not only burdens the patient but also increases the amount of X-ray exposure. In addition, for the doctor, not only the operational burden increases, but the patient throughput also decreases.

Therefore, in recent years, a digital plane that selects a standard plane that seems to be optimal for the patient from a plurality of standard planes prepared in advance and moves the X-ray imaging system while focusing on the selected standard plane before imaging. Shaped panoramic imaging devices are also being used clinically.
On the other hand, as one of the techniques for displaying a photographed image of a dentition, there is a use of a template described in Citation 2. This is for the convenience of interpretation, storage, and management by arranging a plurality of partial images related to the dentition of the subject imaged by the intraoral imaging apparatus in a plurality of templates created in correspondence with the arrangement of the dentition. It is going to plan.

JP-A-4-144548 US Pat. No. 5,179,579

  However, even with digital panoramic imaging using various dental panoramic imaging apparatuses such as the apparatus described in the above-mentioned cited document 1, a cross-sectional image with reduced blur can be quickly obtained. There are many points that need to be resolved in terms of provision. In other words, there is a need for the subject's dentition to be provided in a state where the position of the cross-section to be observed can be freely changed three-dimensionally and the focus is optimized for the cross-sectional image of the changed position with less blur. There is, but it is far from it. When it is desired to examine an image of a cross section different from the standard surface, it is necessary to perform imaging again, and the above-described burden on the patient, an increase in the X-ray exposure, an increase in the burden on the dentist, and a decrease in the patient throughput are reduced. There are difficulties in terms.

  On the other hand, the template described in the cited document 2 is effective in itself. That is, the template can be customized at each dentist or dental clinic. For this reason, a digital cross-sectional image photographed by the intraoral photographing apparatus can be stored in this customized template for interpretation (observation), storage, and management. However, in the case of this template, the function is simply a function of pasting and using a photographed digital cross-sectional image, and it is pointed out that the function is insufficient.

  The present invention has been made in view of the situation of the above-described conventional digital panoramic radiography, and uses digital panoramic image data obtained by X-ray radiography along an arbitrary cross section along a patient's dentition. The position of the cross section of the dentition can be freely changed three-dimensionally, and the cross-sectional image of the changed position is provided with less blur with optimized focus, and An object of the present invention is to provide a panoramic image photographing apparatus having a template function that is not limited to simple image storage by doubling the usefulness of the three-dimensional position information possessed.

  In addition, the present invention provides a cross-sectional image with less blur that optimizes the focus described above, and doubles the usefulness of the three-dimensional position information of the cross-sectional image, so that the template is not limited to mere image storage. Another object of the present invention is to provide an image processing method capable of exhibiting a function.

  In order to achieve the above-described object, according to one aspect of the panoramic imaging apparatus according to the present invention, an X-ray source that emits X-rays and a digital electric signal corresponding to the incident X-rays at a constant frame rate. And a moving drive means for moving the X-ray source and the detector pair around the object in a state where the X-ray source and the detector pair are opposed to each other with the object sandwiched therebetween, Storage means for sequentially storing, as frame data, electrical signals output by the detector at the frame rate as the radiation source and the detector are moved around the object, and stored in the storage means Panorama image generation means for generating a panoramic image of a desired tomographic plane designated in advance based on the frame data; and from the panoramic image data, A partial cross-sectional image generating means for generating a partial cross-sectional image of an optimum focus corresponding to a position in a space where the X-ray source and the detector are moved by the movement driving means for each of the plurality of defined partial areas; A template comprising a plurality of pasting areas that are two-dimensionally arranged in a predetermined format in association with the attribute of the imaging region of the object, and the plurality of partial cross-sectional images are pasted on the plurality of pasting areas of the template; And a template processing means for displaying and saving.

  In addition, according to the image processing method of the panoramic image photographing apparatus according to the present invention, an X-ray source that emits X-rays, and a detection that outputs a digital signal corresponding to the incident X-rays at a constant frame rate. A pair of detectors are moved around the object in a state of facing each other with the object interposed therebetween, and electrical signals output by the detector at a predetermined frame rate along with the movement are sequentially stored as frame data. And a panoramic image photographing apparatus image processing method for generating a panoramic image of a desired tomographic plane designated in advance based on the stored frame data. The panoramic image of the desired tomographic plane is obtained from the panoramic image data. Of each of a plurality of designated partial regions of the lens according to the optimum focal point corresponding to the position on the space where the X-ray source and the detector are moved by the movement driving means. A surface image is generated, and the plurality of partial cross-sectional images are pasted on the plurality of pasting regions of a template including a plurality of pasting regions that are two-dimensionally arranged in a predetermined format in association with the attribute of the imaging region of the object. It is characterized by being attached and displayed.

  The best mode (embodiment) for carrying out the present invention will be described below with reference to the accompanying drawings.

  With reference to FIGS. 1 to 39, an embodiment of a panoramic image photographing apparatus according to the present invention will be described.

  FIG. 1 shows an external appearance of a panoramic image photographing apparatus 1 according to this embodiment. As shown in the figure, the panoramic image photographing apparatus 1 includes a housing 11 that collects gray-level original image data for generating a panoramic image from a subject (patient) P in a standing posture of the subject, for example. For controlling the collection of data performed by the housing 11, generating the panorama image by capturing the collected data, and performing post-processing of the panorama image interactively with the operator (doctor, engineer), And a control / arithmetic unit 12 composed of a computer.

  The housing 11 includes a stand unit 13 and a photographing unit 14 that can move up and down with respect to the stand unit 13. The stand unit 13 includes a base 21 that is fixedly placed on the floor and a support column 22 that is erected on the base 21. In this embodiment, the support column 22 is formed in a prismatic shape, and the photographing unit 14 is attached to one of its side surfaces so as to be movable up and down within a predetermined range.

  Here, for convenience of explanation, an XYZ orthogonal coordinate system is set in which the longitudinal direction of the support column 22, that is, the vertical direction, is the Z axis. Note that, for a two-dimensional panoramic image described later, the horizontal direction is expressed as an x-axis and the vertical direction is expressed as a y-axis.

  The imaging unit 14 includes a vertical movement unit 23 having a substantially U-shape when viewed from the side, and a rotation unit 24 supported by the vertical movement unit 23 so as to be rotatable (rotatable). The vertical movement unit 23 can move in the Z-axis direction (vertical direction) over a predetermined range in the height direction via a drive mechanism 31 (for example, a motor and a rack and pinion) installed in the column portion 22. It has become. A command for this movement is issued from the control / arithmetic unit 12 to the drive mechanism 31.

  As described above, the vertical movement unit 23 is substantially U-shaped when viewed from one side surface thereof, and includes an upper arm 23A and a lower arm 23B on each of the upper and lower sides, and upper and lower arms 23A and 23B. The connecting vertical arm 23C is integrally formed. The vertical arm 23 </ b> C is supported by the column 22 described above so as to be movable up and down. Of these arms 23A to 23C, the upper arm 23A and the vertical arm 23C cooperate to define an internal space. A rotation drive mechanism 30 (for example, an electric motor and a reduction gear) for rotation drive is installed inside the upper arm 23A. The rotation drive mechanism 30 receives a rotation drive command from the control / arithmetic unit 12. The output shaft of the rotation drive mechanism 30, that is, the rotation shaft of the electric motor is arranged so as to protrude downward (downward in the Z-axis direction) from the upper arm 23A, and the rotation unit 24 can be rotated around this rotation shaft. Is bound to. That is, the rotation unit 24 is suspended by the vertical movement unit 23 and is rotated by being energized by the drive of the rotation drive mechanism 30.

  On the other hand, the lower arm 23B is extended to have a predetermined length in the same direction as the upper arm 23A, and a chin rest 25 is formed at the tip thereof. A mouthpiece 26 is detachably attached to the chin rest 25. The subject P holds the mouthpiece 26. For this reason, the chin rest 25 and the mouthpiece 26 serve to fix the oral cavity of the subject P.

  The rotating unit 24 has an appearance that is formed in a substantially U shape when viewed from one side surface in the state of use, and is rotatable to the motor output shaft of the upper arm 23A so that its open end can be rotated downward. It is attached. Specifically, a horizontal arm 24A that rotates (rotates) in the horizontal direction, that is, substantially parallel in the XY plane, and left and right vertical arms (first axis) extending downward (Z-axis direction) from both ends of the horizontal arm 24A. Vertical arm, second vertical arm) 24B, 24C. The horizontal arm 24 and the left and right first and second arms 24B and 24C play an important role in data collection, and the mechanisms and parts necessary for this are provided in the internal space defined by the arms 24A to 24C. It is equipped and is driven and operated under the control of the control / arithmetic unit 12.

  Specifically, an X-ray tube 31 as a radiation source is provided at the lower end inside the first vertical arm 24B, and X-rays can be exposed from the exit window toward the second vertical arm 24C. It has become. On the other hand, a digital X-ray detector 32 in which X-ray detection elements as radiation detection means are arranged in a two-dimensional slit shape (for example, a 64 × 1500 matrix shape) at the lower end inside the second vertical arm 24C. It is equipped and detects X-rays incident from this entrance window. As an example, the detector 32 includes a CdTe line detector (for example, 6.4 mm wide × 150 mm long). The detector 32 is arranged in the vertical direction with its vertical direction coinciding with the Z-axis direction. At the entrance IW of the detector 32, the scattered X-rays to the detector 32 are blocked, and the incident X-rays are actually collected through a window (for example, a window having a width of 3.5 mm; therefore, the lateral direction of the detector 32). Is provided with a slit-like collimator 33 (corresponding to the incident surface 32A of the detector 32). Thus, for example, incident X-rays can be collected as image data of a digital electric quantity corresponding to the amount of X-rays at a frame rate of 300 fps (one frame is, for example, 64 × 1500 pixels). Hereinafter, this collected data is referred to as “frame data” (also referred to as original frame data).

  For this reason, at the time of imaging, the pair of the X-ray tube 31 and the detector 32 is positioned so as to face each other across the oral cavity of the subject P and is driven so as to rotate around the oral cavity as a unit. Is done. At this time, the pair of the X-ray tube 31 and the detector 32 has a predetermined focus on a desired cross section (more precisely, a standard plane (standard tomographic plane) described later) along the dentition of the oral cavity, and the standard. It is rotationally driven to follow the surface. The shape of this standard surface when viewed from the Z-axis direction is substantially horseshoe-shaped. When following this standard plane, the X-ray tube 31 and the detector 32 do not necessarily rotate at the same angular velocity, but as a superordinate concept, the rotation can also be called “movement along an arc”. The standard surface is a surface parallel to the detection surface 32A (see FIG. 2) of the detector 32. In the present embodiment, the detection surface 32A is positioned so as to coincide with the Z-axis direction.

  FIG. 2 shows an electrical block diagram for control and processing of this panoramic image photographing apparatus. As shown in the figure, the X-ray tube 31 is connected to the control / arithmetic apparatus 12 via a high voltage generator 41 and a communication line 42, and the detector 32 is connected to the control / arithmetic apparatus 12 via a communication line 43. ing. The high voltage generator 41 is provided in the support column 22, the vertical movement unit 23, or the rotation unit 24. It is controlled according to the shooting conditions and the sequence of exposure timing.

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

  Of these, the interfaces 51 and 52 are connected to the high voltage generator 41 and the detector 32, respectively, and communicate control information and collected data exchanged between the controller 57 and the high voltage generator 41 and the detector 32. Mediate. Another interface 62 connects the internal bus 50 and a communication line, and the controller 57 can communicate with an external device. As a result, the controller 57 can capture the intraoral image captured by the external intraoral X-ray imaging apparatus, as well as a panoramic image captured by the present imaging apparatus and a focus optimized image (described later) based on the image, for example. According to the DICOM (Digital Imaging and Communications in Medicine) standard, it can be sent to an external server.

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

  The image processor 56 is placed under the control of the controller 57 and interactively generates a panoramic image of the standard surface along the patient's dentition and the subsequent use of the panoramic image with the operator. Has the function to execute. A program for realizing this function is stored in the ROM 61 in advance. In this embodiment, the standard plane is a tomographic plane selected from a plurality of prepared tomographic planes. That is, the position of the standard surface can be changed within a certain range in the depth direction of the dentition. The post-processing for generating and interpreting the panoramic image is one of the core features of the panoramic image photographing apparatus, and will be described in detail later.

  Frame data and image data processed by the image processor 56 or being processed are stored in the image memory 54 so as to be readable and writable. For the image memory 54, a large-capacity recording medium (nonvolatile and readable / writable) such as a hard disk is used. The frame memory 55 is used to display the generated panoramic image data and / or post-processed panoramic image data. The image data stored in the frame 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 constituent elements of the apparatus in accordance with a program responsible for overall control and processing stored in the ROM 61 in advance. Such a program is set so as to interactively receive operation information on predetermined items from the operator. For this reason, as will be described later, the controller 57 generates parameters that are necessary for reconstruction (which will be described later) that is responsible for generating a panoramic image of the standard plane and optimizing the focus of the panoramic image (that is, processing that reduces blurring of the image). Gain) setting, frame data collection (scanning), and operation information of the operator output from the operating device 58 can be taken into account and interactive control can be performed.

  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 posture, holds the mouthpiece 26, and presses the forehead against the headrest 28. As a result, the position of the patient's head (jaw) is fixed at substantially 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 an oblique plane on the XY plane (see arrows in FIG. 1). .

  During this rotation, under the control of the controller 57, the high voltage generator 41 supplies a high voltage for irradiation (specified tube voltage and tube current) to the X-ray tube 31 in a pulse mode of a predetermined cycle. Then, the X-ray tube 31 is driven in a pulse mode. As a result, pulsed X-rays are emitted from the X-ray tube 31 at a predetermined cycle. The X-rays pass through the patient's jaw (dental portion) located at the imaging position and enter the line sensor type 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 two-dimensional digital data (for example, 64 × 1500 pixels) of the corresponding electric quantity. This digital data is handled as the frame data described above, and is temporarily stored in the buffer memory 53 via the communication line 43 and the interface 52 of the control / arithmetic apparatus 12. The temporarily stored frame data is then transferred to the image memory 53 and stored.

  For this reason, the image processor 56 generates a panoramic image along the standard surface along the dentition by reconstruction using the frame data stored in the image memory 53, and the region of interest designated on the panoramic image. A focus-optimized image is generated by reconstruction using the frame data forming (ROI). It should be noted here that the panoramic image itself is an entire cross-sectional image of the standard surface generated with the intention of optimizing the focus. However, in actuality, there is a difference in the shape of each dentition of the subject, so the image with the least out-of-focus (in-focus, that is, the focus is optimized) for each region on the standard surface alone Hard to get. For this reason, in this embodiment, based on a panoramic image of a standard surface (a cross-sectional image covering at least the entire dentition), a cross-sectional image showing the internal structure more clearly (with less blur and in focus) Reconfiguration to get. In many cases, the post-reconstruction is usually performed on a partial area of the panoramic image as a base, and the cross-sectional image of the partial area is referred to as a focus optimized image here.

  Thus, both the generation of the panoramic image and the generation of the focus optimized image involve a process called reconstruction. As will be described in detail later, this reconstruction is simply a process of superimposing and adding frame data (pixel values) to each other. Note that the region of interest set on the panorama image is normally specified on the panorama image as a local region that forms a part of the panorama image, but the entire panorama image can also be set as the region of interest. . Of course, the focus optimization image is generated when a doctor or the like desires.

  The panorama image and / or the focus optimized image is stored in the image memory 54 and displayed on the monitor 60 in an appropriate manner. Among these, at least the selection of the standard surface, the setting of the region of interest, the change of the cross-sectional position, the display mode, and the like reflect the operator's intention given from the operating device 58.

  The panoramic image capturing and interpretation using the panoramic image capturing apparatus 1 is generally as described above, but the concept called “gain” is used to generate the panoramic image of the standard plane and the focus optimized image of the designated area. Has been introduced. In this embodiment, the “gain” is set in advance by calibration, and the gain data is stored in a predetermined area of the image memory 54 in advance as a lookup table LUT.

  Therefore, including the above-described concept of “gain” and “setting of gain using phantom”, panorama image generation of the entire dentition and focus optimization image of the designated region executed by the panorama image photographing apparatus 1 are performed. Details necessary for generation will be described for each item.

(Gain concept)
In this panoramic image photographing apparatus 1, panoramic images of a standard plane (desired tomographic plane) along a specified (or selected as will be described later) panoramic image are frame data (elongated, for example, 300 fps). A two-dimensional slit shape, which is actually a set of X-ray transmission data regarded as a line shape) is generated by overlapping each other while shifting the position. This superposition is a process that forms the core of “reconstruction”. In other words, it utilizes the fact that the degree of contrast of pixel values increases due to superposition, and structures (teeth, gums, etc.) are rendered at a higher density than other parts. Here, when a plurality of sets of frame data are superimposed on each other and added, an amount indicating the degree of superposition of how much the frame data of each set is overlapped, that is, “between frame data The “overlapping amount” is called gain.

  When this gain is small, the degree of superposition is dense, and when the gain is large, the degree of superposition is coarse. The manner of superimposing the frame data is schematically shown in FIGS. FIG. 6A shows superposition when the gain is small, and FIG. 4B shows superposition when the gain is large. As described above, the concept of the degree of superposition (dense / dense) accompanying the magnitude of the gain is opposite to that of a normal electric circuit. As will be described later, this is a coordinate with the horizontal axis as the position where the frame data is the horizontal axis and the frame data are mutually added in the memory space (mapped position, that is, the pixel position of the reconstructed panoramic image). This is due to the “equivalent to the slope” of the upper curve (called the speed curve). This speed curve will be described later.

  Furthermore, as described above, when the gain, that is, the amount of overlap of frame data is adjusted, the image density changes between images to be generated. In other words, if the cross-section to be reconstructed is changed, the shade changes between images as it is, making it difficult to interpret. For this reason, it is necessary to multiply the pixel value of the reconstructed image by a coefficient proportional to or directly proportional to the gain to be used, so that the apparent shading is the same between the images.

  An example of this gain will be described using the simplified model of FIG. As shown in the figure, the X-ray tube 31 and the detector 32 have distances D1 and D2 with respect to each other object OB (patient's jaw dentition) (X-ray tube being scanned at each point of the dentition, respectively). If the relative ratio of the direction along the straight line (hereinafter referred to as the depth direction) connecting the detector and the detector is kept constant and the relative motion speed is kept at a certain value, the object OB The amount (gain) of overlay of frame data that is not blurred (that is, in focus) is determined.

  In other words, when scanning is performed as described above, a focal plane (a continuous cross-section in focus) is determined based on the relative operation speed and gain. Since this focal plane corresponds to the ratio of the distances D1 and D2, the focal plane is located on a plane translated from the detector 32 in each depth direction.

  In general, as the gain decreases, the focal position becomes closer to the X-ray tube 31 in each depth direction Ddp, and as the gain increases, the focal position moves away from the X-ray tube 31 in each depth direction Ddp. For this reason, using a phantom (to be described later) that quantitatively understands the distance interval between the X-ray tube 31 and the detector 32 in each of the depth directions, a quantitative measurement (setting of how much the gain is focused) ) Is performed in advance for each position on a 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, and the relationship information may be held as, for example, a lookup table LUT as described above.

  This pre-measurement scan is performed by placing a phantom at the position of the chin rest 25 and rotating the pair of the X-ray tube 31 and the detector 32. The trajectory and speed of this rotation are based on actual imaging of the subject P ( It is set to be the same as that of scanning.

  Further, from the characteristics of the gain, the gain in the vertical direction, that is, the direction (Z-axis direction) parallel to the detection surface 32A of the detector 32 (the surface on which X-rays are incident: see FIG. 2) is constant for each position on the XY plane. It is. That is, when the detector 32 is at a certain position, the gain at each position (in the XY plane) in the depth direction passing through the detector 32 is different for each position, but is parallel to the detection surface 32 passing through the position. The same value is taken in all directions (Z-axis direction).

  Of course, in addition to the method based on the above-described table reference, the relationship between the values may be held by an arithmetic expression, and the gain may be obtained by calculation each time a position in the depth direction is given. In addition, the gain is obtained for each position in the depth direction, but finally, using this obtained gain, the gain of the scan space (the space including the dentition) including the whole of the position is converted into polar coordinates and It may be converted into a value expressed in rectangular coordinates, and this conversion gain may be used.

  Therefore, by referring to the lookup table LUT, it is possible to obtain the gain of each mapping position along the tomographic plane when focusing on a tomographic plane different from the standard plane to be reconstructed first. By superimposing the frame data on each other using this gain, the pixel value of the panoramic image at each mapping position on the standard plane can be obtained. Such a plane is basically a plane perpendicular to the XY plane, but may be an oblique plane oblique to the XY plane (and the YZ plane and / or the XZ plane).

(Phantom used for pre-measurement)
As described above, in order to quantitatively measure the relationship between the distance in the depth direction and the gain in advance, a phantom is used in this embodiment.

  Generally, since the tooth arrangement, that is, the dentition is a horseshoe shape, it is divided into a plurality of scan regions (anterior tooth region or back tooth region) according to the curvature, and the horseshoe shape while changing the distances D1 and D2 described above. Scan to follow the set standard plane along Thus, using the phantom, the distance and gain in each depth direction at predetermined intervals in the direction along the dentition (for example, the distance between the i-th and i + 1-th in the depth direction in FIG. 4 is 10 mm). It is desirable to quantitatively measure this relationship.

  Examples of phantoms used for this preliminary measurement are shown in FIGS. 5 and 6 illustrate the first phantom FT1. The phantom FT1 is preferably a base 71 (see FIG. 6), which is a strong plate with little X-ray absorption, such as a lead plate, and has a substantially horseshoe shape, and a predetermined angle from one end of the base 71. A plurality of measurement plates 72 (see FIG. 5) made of an acrylic plate or the like extending obliquely upward with θ (for example, 45 degrees), a chin rest fixing portion 73 extending downward from the other end of the base portion 71, and On one surface of the measurement plate 72 over a predetermined distance (horizontal plane (XY plane)) over a predetermined distance in the longitudinal direction (a distance corresponding to a predetermined distance range R1 (for example, 20 mm) on the horizontal plane (XY plane)). And a plurality of phantom bodies 74 made of lead balls or the like arranged at a distance of a minute distance R2 (for example, a distance corresponding to 5 mm).

  Among these, the angle θ of the measurement plate 72 with respect to the base 71 is an angle for inclining by the angle θ with respect to the X-ray projection direction. In addition, the plurality of measurement plates 72 are arranged along the tooth row so as to virtually cross the tooth row (see the dotted line L1 in FIG. 6), and a predetermined distance between them is near the back teeth. The pitch is set to about P1 (for example, 10 mm). (See FIG. 6). The phantom body 74 is smaller than the minute distance R2 and has a diameter (for example, a diameter of 1 mm) that allows sufficient visual observation of blur. For this reason, the minute distance R2 is a process between the center positions of the two adjacent phantom bodies 74. Further, the predetermined processing range R1 is set to a range to be observed as a horseshoe cross section of the dentition.

  It should be noted that the mounting position of the measurement plate 72 with respect to the base 71 is preferably adjustable by the adjusting mechanism AD in the depth direction by shifting the screwing position.

  FIG. 7 illustrates another phantom FT2. In this phantom FT2, instead of the phantom body 74 disposed on the measurement plate 72 of the phantom FT1, a strip-like and thin-film phantom body 74A made of hard lead is disposed. The size of the phantom body 74A is, for example, a width of 5 mm, a length of 21.2 mm (predetermined distance range R1), and a thickness of about 0.5 mm. Each position in the longitudinal direction of the phantom body 74A can be determined based on linearity if the distance between one end face of the phantom body 74A and one end face of the measurement plate 72 is known. Other structures are the same as those shown in FIGS.

  Even when any of these phantoms FT1, FT2 is used, it is possible to measure the focal blur and distance. That is, in the case of the first phantom FT1, the degree of blurring of the lead ball image forming the plurality of phantom bodies 74 on each measurement plate 72 is visually observed from the panoramic image collected by the scan for the pre-measurement. In the case of the other second phantom FT2, the degree of blur between the strip-shaped lead plate forming the phantom body 74A on each measurement plate 72 and the end face of the measurement plate 72 itself is visually observed from the same panoramic image. Based on this observation result, if there is a blur for each phantom body 74 of each measurement plate 72 or the longitudinal direction of the phantom body 74A of each measurement plate 72, the gain is adjusted by trial and error. The image is observed, and the gain when the blur is the least is determined as the focus optimization gain at that position in the depth direction. In other words, this gain is about the superposition of frame data providing an image with the least blur. The image processor 56 recognizes the degree of superposition at the position of each phantom body, and passes an amount indicating the degree to the controller 57 as a gain.

  The phantom FT may be configured by periodically arranging objects that do not transmit plate-like X-rays along the dentition. In the case of this structure, it is made of a material that does not transmit the distance guide in the depth direction. In this case, a method of searching for a gain in which the appearance of the boundary between the non-transmitting plate material and the transmitting portion is sharply blurred is adopted.

(Lookup table)
As described above, the focus optimization gain at each position (distance) in the depth direction intersecting each position of the dentition is stored in a predetermined area of the image memory 54 as a lookup table LUT in this embodiment. . If the lookup table LUT is held in this way, an arbitrary cross section along the dentition can be reconfigured with the degree of freedom of the lookup table LUT.

  By the way, the position where the above-mentioned pre-measurement is performed is defined as a distance from the standard plane on a straight line connecting the X-ray tube and the detector during scanning, that is, in each depth direction during scanning. For this reason, in order to create a look-up table LUT adapted to a three-dimensional voxel space, the above-described gain of each sample point in this voxel space may be created by interpolation from known gains in the vicinity (calibration). ) As a result, as shown in FIG. 8, the gain is set by the horseshoe-shaped three-dimensional voxel corresponding to the range R1 of the predetermined distance along the horseshoe-shaped dentition, for example, at equal intervals in the same horseshoe section on the XY plane. Gain is set. As described above, the gain value in the Z-axis direction (vertical direction) is the same at each sample position (for example, the position of (N−1, SD)), and therefore the calculation for that amount may be omitted. it can. Therefore, the look-up table LUT has information indicating the correspondence relationship between the position shown in FIG. 8 (position as a distance from the standard surface) and the gain corresponding to the position.

  For this lookup table LUT, how to determine the optimal number of gains of detailed sample points (finely the pitch between sample points) is determined from the viewpoint of achieving both image quality and calculation time. is important. Basically, it is preferable to have a sample point gain as detailed as possible, and to perform two-stage cross-sectional reconstruction using this gain. In the first stage, the panoramic image of the standard surface is reconstructed with a relatively coarse gain so that the entire dentition can be observed quickly. In the second stage, the region of interest is extracted from the entire panoramic image. For example, it is possible to specify manually, and a panoramic image of the region of interest is reconstructed with a preset detailed gain. Thereby, the gain can be set by the interpolation calculation with higher accuracy, and then the local region based on the high accuracy gain after the overall observation can be observed in more detail.

  Even when this two-stage reconstruction method is employed, it is important to obtain a panoramic image (entire dentition image) at a more appropriate cross-sectional position in the first stage. This is to prevent the oversight by grasping a site such as a lesion from the beginning. For this reason, it is important to specify the dentition cross section (standard surface) that matches the shape and size of each patient's dentition as much as possible.

(Speed curve)
Next, a method for reconstructing a cross-sectional image along a horseshoe-shaped dentition using the above-described gain will be described. The basic idea is the speed curve shown in FIG.

  In FIG. 9, the horizontal axis indicates the frame number (for example, 1 to 4096) of the frame data, and the vertical axis indicates the position where the frame data is added in the memory space. A curve CA indicates the position in the memory space mapped after the panoramic image reconstruction with respect to the frame number of the frame data in the cross section designated as the standard plane output from the detector 32 according to the present embodiment. This is a standard pattern of dotted speed curves.

As can be seen from this graph CA, in the standard surface, the inclination (that is, gain) of the graph is different between the side surface (back tooth portion) of the dentition and the front surface, and the inclination of the side surface is about −1.5, It is designed at about -0.657.
This standard pattern is preset in advance, and in the case of a desired collection position of a human dentition, an image that is not optimally focused can be obtained due to individual differences in tooth profile or variations in the desired position. There is sex. For example, in order to obtain an image in which the focus is optimized in an individual, as shown by a curve CB in FIG. 9, it is only necessary to collect while slightly changing the speed depending on the scanning position. It becomes complicated. Therefore, in this embodiment, instead of such complicated scan control, the degree of superimposition (that is, gain) of collected frame data is adjusted. The basis of this is the speed curve described above. A panoramic image reconstruction equivalent to changing the actual collection speed along the cross-section represented by the designated desired curve, such as the curve CB, can be performed as post-processing for the overlay amount of the frame data.

(Basic idea of focus optimization)
First, as shown in FIG. 10, a panoramic image (base image) of a standard surface along a dentition, which is standardly prepared by designating or selecting on the apparatus by an image interpreter, is basic. This image interpreter uses this panoramic image to grasp the entire state of the dentition. While observing the panoramic image, the image interpreter selects an ROI (region of interest: hereinafter referred to as “ROI”) as a local region of interest on which the focus is more desired (focus optimization is desired). Set as). FIG. 10 shows two ROIs (ROI1, ROI2).
ROI1 specifies a smaller area that covers only the portion that is truly desired for both the x-axis and the y-axis. The size of this ROI 1 can be set to almost the same value as that of the X-ray film used in the conventional intraoral photographing method. In addition, in the case where the side teeth are imaged by the intraoral imaging method, the dentition is set so as to enter the X-ray film. In this embodiment, ROI1 is set so that the side teeth fit within the ROI. It is also preferable to rotate (tilt) the cross-section designated by (2) from the plane of the panoramic image parallel to the x-axis and the y-axis. Cross sections from various directions and angles having the size of this small region (translated cross section, inclined (rotated) cross section, cross section of those translated and inclined (rotated) appropriately combined, As will be described later, an image of a curved cross section matching the curved shape of each tooth is subjected to a focus optimization process.
On the other hand, ROI2 exemplifies a larger range specification that is specified when the focus is optimized over the entire dentition. In any case, since the region to be processed can be limited by specifying the ROI in this way, the amount of calculation for optimizing the focus, which will be described later, can be reduced and the processing time can be shortened. it can.
In addition, when specifying ROI <ROI1, RO2> on the base image in this way, it is desirable to limit the range of the ROI in the y-axis (vertical) direction. The reason is that data in the vertical direction that does not need to be optimized is excluded from the calculation for the focus optimization to reduce the calculation amount, thereby increasing the calculation speed.

  As described above, after the ROI is designated, various cross sections having sizes determined by the ROI are designated interactively. The apparatus applies only the image of the cross-section so designated to the focus optimization process. This process is automatically performed in response to a command from the operator for taking a cross section. As a result, the local cross-sectional image corresponding to the ROI can be displayed on the monitor 60 with its focus optimized, and can be used for detailed observation.

  In addition, when displaying this optimized ROI image, that is, a local cross-sectional image, on the monitor 60, a display method that reduces a sense of discomfort due to the conventional X-ray film intraoral imaging method is preferable. Specifically, it is convenient to display the vertical and horizontal sizes of such local cross-sectional images according to the actual distance.

(Overview of focus optimization)
This focus optimization process is executed by the image processor 56 as shown in FIG.

  When receiving a focus optimization command, the image processor 56 reads the speed curve CA of the standard plane, and refers to the speed curve CA and the designated ROI, and the horizontal direction of the ROI (time series direction of the frame data). In this case, the frame data FDc which is the center of the frame is specified as schematically shown in FIG. 12 (step A1). Next, the image processor 56 specifies a plurality of frame data FDb ′ to FDe ′ corresponding to the entire region of ROI from the speed curve CA around the frame data FDc as schematically shown in FIG. 12 (step A2). . At this time, since the detector 32 has a usable effective width, it is desirable to add frame data FDb and FDe for the effective width to the left and right of the group of the frame data FDb ′ to FDe ′, respectively.

  Next, the image processor 56 superimposes and adds (reconstructs) the frame data FDb to FDe specified according to the speed curve CA of the standard surface (step A3). That is, each of the frame data FDb to FDe is mapped to each mapping position (vertical axis in FIG. 12) in the ROI according to the speed curve CA (see mapping directions P1 and P2). At the time of mapping, the pixel value at the center position of each frame data is set to zero (0), and the offset of the pixel value at the time of superposition is eliminated. The mapping position is actually a two-dimensional position, but will be described in one dimension for easy understanding.

  By such mapping, data from a plurality of frame data is superimposed on each mapping position (pixel position), and these data are added. Thereby, the pixel value at each mapping position is calculated, and a partial cross-sectional image (in this case, a part of the panoramic image of the standard plane) is generated. As a result, the gradient of the speed curve CA, that is, the shade corresponding to the gain is formed in each pixel forming the ROI, and the dentition structure appears on the panoramic image.

  Next, the image processor 56 interactively determines whether or not to change the position information to be reconstructed (in this case, not only the position in the depth direction of the region defined by the designated ROI but also its angle is included) ( Step A4). If there is a position change, the gain corresponding to the changed position information is read from the lookup table LUT (step A5). This read gain is integrated in the direction of the center pixel of the frame data to calculate a corrected speed curve CB (step A6).

  At this time, since the size of the ROI is a fixed value, the number of frames of frame data necessary for reconstruction of a new position is different. Therefore, the frame data necessary for reconstruction of the area is specified so that the frame data FDc as the center specified in step A1 described above also becomes the center position in the area at the correction position (step A7). Note that the number of frame data may be increased or decreased according to the correction position so that the size of the new area at the correction position is the same as the size of the first ROI.

  When this preparation is completed, the image processor 56 is changed in the same manner as described above (see step A3) based on the speed curve CB obtained in step A6 and the plurality of frame data specified in step A7. The cross-sectional image of the partial area is reconstructed (step A8). At this time, the speed curve CB used at the time of reconstruction is represented as shown by, for example, a virtual line in FIG.

  Further, a coefficient proportional to or directly proportional to the gain (corresponding to the cross-sectional position) used for reconstruction is multiplied by each pixel value of the cross-sectional image generated by the reconstruction (step S9). Thereby, it is possible to almost eliminate the difference in apparent shading between images, and even if the cross-sectional image changes, it is easy to see and the interpretation work can be facilitated.

  The cross-sectional image generated in this way is not a part of the panoramic image along the standard plane, but is a cross-sectional image at a partial position changed based on the ROI specified on the panoramic image. If the cross-sectional image is desired by the interpreting doctor, the image data of the cross-sectional image and the position information (depth direction position and angle information) of the image are stored (steps A10 and A11). If not, the process returns to step A4 (step A10).

  Next, an example of processing related to gain pre-measurement, panorama shooting, and image interpretation executed by the panoramic image photographing apparatus 1 according to the present embodiment will be described with reference to FIGS.

(Gain pre-measurement)
First, referring to FIG. 13, gain pre-measurement (when the gain has already been set, gain calibration will be described).

  As described above, the gain is an amount that means “the degree of superposition” when frame data are overlapped and added to each other, and the gain for achieving an optimal focal position without blur is the tooth It changes according to each position (distance) in each depth direction intersecting the column. As the gain decreases, the focal position becomes closer to the X-ray tube 31 in each depth direction, and as the gain increases, the focal position moves away from the X-ray tube 31 in each depth direction.

  In order to set and hold the gain in advance, the controller 57 of the control / arithmetic apparatus 12 interactively performs the process schematically shown in FIG. 13 with the operator.

  In the prior gain measurement, the phantom FT is fixed at the position of the chin rest 25 (see FIG. 1) instead of the subject. The position of the fixed phantom FT corresponds to a spatial position determined as a standard position of the dentition when the dentition of the subject P is actually photographed, as will be described later. As the phantom FT, the one shown in FIG. 5 or 7 is used as described above. In accordance with the position of the phantom FT in the Z-axis direction, the vertical movement unit 23 is arranged so that the cross-section of the X-ray tube 31 irradiated X-ray collimated by the collimator is positioned in the slit beam. The height is adjusted.

  When the fixed arrangement of the phantom FT is completed, the control / arithmetic unit 12 receives an X-ray irradiation condition (tube voltage, tube current, scan time, etc.) from the operator (step S1).

  When the condition setting is completed, the rotary unit 24 (that is, the pair of the X-ray tube 31 and the detector 32) is moved (scanned) around the phantom FT along the XY plane in response to a command from the operator. While the X-ray tube 31 is irradiated with X-rays, the detector 32 detects transmission X-rays of a high-speed frame, and frame data is collected (step S2). That is, as an example, frame data is output from the detector 32 at a high frame rate of 300 fps, and the frame data is transferred to the image memory 54 via the buffer memory 53 and stored.

  Next, the controller 57 instructs the image processor 56 to reconstruct a panoramic image of the dentition cross section (predetermined surface) at a predetermined spatial position using the collected frame data (step S3). As shown in FIG. 14, the predetermined plane is along the center line ST of the subject's standard dentition (that is, a dentition in which each tooth is aligned on a horseshoe-shaped locus of a standard size). This predetermined plane is made to coincide with a reference plane among a plurality of standard planes prepared so as to be selectable in actual photographing described later.

  The gain G for each position Pn on the predetermined plane (that is, the position where each depth direction Ddp intersects the standard plane) is determined in advance as the slope of the speed curve of the standard plane indicated by the curve CA in FIG. ing. Therefore, the image processor 56 calls all the collected frame data from the image memory 54 as described above, and adds the frame data to the mapping position determined according to the speed curve CA (that is, overlapped and added). The standard plane panoramic image is reconstructed.

  Next, the controller 57 displays the reconstructed panoramic image of the standard plane on the monitor 60 (step S4). An example of this display is shown in FIG. As shown in the figure, five left end measurement plates 72L, a left intermediate measurement plate 72LC, a central measurement plate 72C, a right intermediate measurement plate 72RC, and a right end installed on the phantom FT at a predetermined inclination angle of 45 degrees. A panoramic image of the standard surface on which the measurement plate 72R is reflected is displayed. A plurality of phantom bodies 74 are transferred on each measurement plate, but although only schematically shown in the figure, the spatial position of the central region in the plate longitudinal direction (depth direction) corresponding to the standard surface 1 or a plurality of phantom bodies 74 in a state where the blur is the least, that is, a state where the focus is most focused.

  Here, the longitudinal direction of the plate is roughly divided into five types: the outermost peripheral region Rotm, the outer peripheral region Rot, the central region Rc, the inner peripheral region Rin, and the innermost peripheral region Rinm, for the convenience of gain pre-measurement. (See FIG. 15), the standard plane is set to belong to the central region. That is, in the example of the phantom FT1 shown in FIG. 5 described above, the region of the predetermined distance range R1 (for example, 20 mm) projected onto the base 71 (XY plane) is divided into five regions. The predetermined distance range R1 is a range in the depth direction in which the section of the dentition is freely moved to be examined.

  Here, two regions, that is, two cross sections, can be set before and after the standard plane in the depth direction, and five types of cross sections can be measured together with the standard plane. This is schematically shown in FIG. The outermost virtual line is the outermost peripheral section OTM, the next inner virtual line is the outer peripheral section OT, the inner virtual line is the standard plane ST, and the inner virtual line is the inner peripheral section IN. , And the innermost imaginary line indicates the innermost circumferential section INM. The distance in the depth direction between the cross sections is set to 4 mm, for example.

  For this reason, the reason why the depth direction is roughly divided into 5 regions is sufficient if the cross-sectional area of about 20 mm can be secured in the depth direction of the dentition, and it is sufficient to withstand the use. Interpolate the gain. Therefore, when a compromise is made between the calculation amount and the calculation time, it is sufficient to collect five points (gains in five regions) in each depth direction as the gain base data at this stage.

  Next, the operator shifts to an interactive setting operation of gains of cross sections (positions) before and after the depth direction other than the standard plane while visually observing and observing the panoramic image. Specifically, first, the operator selects the first measurement plate 72 in the phantom FT and displays an enlarged image of the measurement plate 72 (step S5; see FIG. 16). This enlarged display is for making the plurality of phantom bodies 74 on the measurement plate 72 easier to see and setting the gain as accurately as possible. This enlarged display will be described using the central measurement plate 72C as an example. The order of the enlarged display for each measurement plate is arbitrary.

  Next, the controller 57 receives operation information from an operator viewing the enlarged central portion measurement plate 72C, and designates a region other than the central region in the longitudinal direction on the central portion measurement plate 72C. (Step S6). In response to the area designation, the controller 57 calculates the position of the designated area in the depth direction and stores the position coordinate information (step S7). Through the processes of steps S6 and S7, first, for example, the outermost peripheral area Rotm of the central measurement plate 72C, that is, the outermost peripheral cross section OTM in the depth direction along the direction in which the central measurement plate 72C is placed. The position of is specified.

  Next, the controller 57 receives the operation information from the operator, and the one or more phantom bodies 74 belonging to the outermost peripheral area Rotm that is currently being observed have no blur (there is almost no blur or the least blur) In other words, it is determined whether or not it is in the best focus as long as it is visually observed (in the optimum focus state) (step S8). Now, since the phantom body 74 is a round lead ball, the operator can determine that it is in an optimally focused state when it is round and its outline clearly appears. In that case, a button (not shown) indicating the optimum focus state on the monitor screen may be pressed. When it can be determined that the optimal focus state has not yet been reached, the operator presses a button indicating the non-optimal focus state on the monitor screen, and in response, a gain change (gain increase, gain) that appears on the monitor screen is displayed. (Step S9).

  When this gain change is performed, a panorama image corresponding to the changed cross-section, that is, the changed position in the depth direction is reconstructed using the changed gain G (step S10). At this time, the calculation time can be shortened by reconstructing only the portion of the center measurement plate 72C related to the currently enlarged display (the region is designated). This newly reconstructed panoramic image is displayed again (enlarged display image) (step S11).

  Thereafter, the process of the controller 57 is moved to step S8, and the presence or absence of blurring of the phantom body 74 belonging to the outermost peripheral area Rotm of the central measurement plate 72C is determined in the same manner as described above. When this determination is NO, there is still room for optimum focusing, so the controller 57 changes the gain in accordance with an instruction from the operator, and reconstructs and displays a panoramic image (steps S9 to S11). . When the gain is changed through trial and error in this way and a panoramic image without blur is obtained (YES in step S8), the operator gains the gain along the depth direction of the center measurement plate 72C. It can be recognized that this is a gain for obtaining an optimum focus at the position of the outermost peripheral section OTM. Therefore, the controller 57 stores the gain at this time in the image memory 54 in response to the operation of the operator, assuming that the gain is the focus optimization gain (step S12).

  Next, the controller 57 shifts the process to step S <b> 13 and determines whether or not the gain measurement has been completed for all the regions in the longitudinal direction on the current measurement plate 72. When this determination is NO (step S13, NO), the controller 57 returns to step S6 and executes another region in the same manner as described above. Thereby, for example, it is possible to measure the focus optimization gain at the position of the outer peripheral section OT corresponding to the outer peripheral region Rot along the depth direction of the central measurement plate 72C.

  If YES is obtained in step S13, the controller 57 further determines whether or not the same focus optimization gain has been measured for all the measurement plates (step S14). If the determination is NO, since the measurement plate to be measured still remains, the controller 57 returns the processing to step S5 and performs the same processing as described above for another measurement plate, for example, the right intermediate measurement plate 72RC. Apply. Thereby, the gain at the position of the cross section corresponding to the region other than the central region Rc in the longitudinal direction of the measurement plate is measured. On the other hand, when the determination of YES is made in step S14, the gain and reference plane in total of 20 points of the cross-sectional positions of the outermost circumference, outer circumference, inner circumference, and innermost circumference using all five measurement plates 72 are used. Thus, gains at a total of 25 positions (positions of black circles in FIG. 17) based on the five gains are obtained as reference data.

  Next, the controller 57 has a total of 25 points mapped to a two-dimensional area (see the hatched portion in FIG. 17) centered on the standard plane ST on the XY plane and having a predetermined distance range R1 along the plane ST. An appropriate interpolation method is applied to the reference gain to calculate gain data (positions marked with x in FIG. 17) for filling the space between the positions having the reference data spatially (step S15). When this interpolation is completed, the gain values of the respective points (positions of black circles and crosses) in the two-dimensional area forming the horseshoe shape are stored in the image memory 54 as a lookup table LUT (step S16). This look-up table LUT includes positions that intersect the standard plane ST, positions that are scattered along the depth direction passing through the positions, and gain values at the positions.

  The gain value in the vertical direction (Z-axis direction) orthogonal to the two-dimensional region has the same value at each point as described above. Therefore, the two-dimensional lookup table LUT indicates a lookup table for a three-dimensional gain.

  As described above, through the series of processes shown in FIG. 13, the gains at the respective positions of the three-dimensional area having the horseshoe-shaped two-dimensional area determined by the predetermined distance R1 in the depth direction centered on the standard surface ST are measured. become. It is sufficient that this gain pre-measurement is performed at the time of factory shipment or at the time of installation of the apparatus, but it may be performed as a calibration at the time of starting the apparatus not only at regular or irregular maintenance management. . In the case of calibration, the contents of the lookup table LUT held so far are updated to new gain data each time.

  The more phantoms used for this pre-measurement and calibration, the more detailed the gain data that can be measured, the more it can measure the gain data. The number of measurement plates and the arrangement position may be determined by comparing the accuracy of the measurement.

(photograph)
Next, imaging, that is, actual data collection will be described with reference to FIG.

  At the time of photographing, the operator inputs patient information such as patient ID, patient name, photographing date and time to the control / calculation device 12 (step S21). In response to this input, the controller 57 records the patient information in a predetermined area of the image memory, and associates it with frame data to be collected later using, for example, the patient ID as key information.

  Next, the subject P (patient) is positioned as described in FIG. That is, the operator adjusts the height of the vertical movement unit 13 and then takes a predetermined image of the oral cavity of the subject using the chin rest 25 and the headrest 28 with the subject P holding the mouthpiece 26. Position to position. This positioning may be performed before the patient information is input, or may be performed after setting the X-ray irradiation conditions described later.

  The controller 57 sets the standard plane used for actual photographing interactively based on the operation information from the operator (step S22). This standard plane is set by selecting several standard planes prepared in advance in the apparatus. This will be described later.

  Furthermore, the controller 57 sets X-ray irradiation conditions (X-ray tube voltage, tube current, scan time, scan trajectory, and the like) based on operation information from the operator, as in the case of gain pre-measurement described above. (Step S23).

  When the preparation is completed in this way, the controller 57 responds to the command from the operator and moves the rotating unit 24 (that is, the pair of the X-ray tube 31 and the detector 32) along the XY plane of the oral cavity of the subject P. While moving (scanning) around, the X-ray tube 31 is irradiated with X-rays, while the detector 32 detects transmission X-rays in a high-speed frame. Thereby, collection of frame data is performed (step S24). That is, as an example, frame data is output from the detector 32 at a high frame rate of 300 fps, and the frame data is transferred to the image memory 54 via the buffer memory 53 and stored.

  Note that image data captured by an external intraoral X-ray imaging apparatus may be received and stored in the image memory 54 before or after the above-described collection of frame data, if necessary.

  After this scan is completed, the subject P is released from the apparatus.

(Interpretation (observation))
When the collection of the frame data is completed by the above-described scan, the doctor can perform interpretation using the frame data as post-processing.

  A series of processes of the controller 57 used for the interpretation are shown in the flowcharts of FIGS. 19 to 23, and an operation example associated with the interpretation is shown in FIGS. Although not specifically mentioned, the controller 57 performs such processing in cooperation with the image processor 56 for processing related to image generation such as panoramic image generation and partial cross-sectional image generation.

  As shown in FIG. 19, the controller 57 receives an input of a patient, that is, an interpretation target, in response to a command from the operator (step S31). Thereby, for example, when information for specifying an interpretation target such as a patient ID and photographing date / time is input, the controller 57 reads out the frame data of the subject P specified by the information from the image memory 56 to its work area (step S32).

Next, the controller 57 instructs the image processor 56 to reconstruct the panorama image of the standard plane and display the panorama image on the monitor 60 (steps S33 and S34). Thereby, as schematically shown in FIG. 21, a panoramic image Ppano of the standard surface of the dentition of the subject P is displayed on the monitor 60. This panoramic image Ppano depicts a cross-sectional structure along the standard plane as with the X-ray transmission image.
These processes are the same as the processes at the time of the prior gain measurement (see steps S3 and S4 in FIG. 13). The processing up to this point corresponds to the preparation stage of the interpretation work. It is desirable that the standard surface can be selectively specified in advance.

  Next, the controller 57 uses the information from the operator via the operation device 58 as to whether or not to further optimize the focus on the partial area of medical interest on the currently displayed panoramic image. Based on the determination (step S35). When this determination is YES, that is, when it is determined that it is desired to observe an image (partial cross-sectional image of teeth and gums) with reduced focal blurring by focusing on a partial (local) region, the controller 57 performs step S36 and subsequent steps. Move on to processing. On the other hand, when the determination is NO, that is, when the interpretation process is to be stopped or the process shifts to another process, the controller 57 shifts the process to a routine not shown.

  If it is determined in step S35 described above that the focus optimization of the partial area is to be performed (YES), the controller 57 next displays the panoramic image and the window of the optimized image area on the screen of the monitor 60 (step S36). In this divided display, as illustrated in FIG. 24, a panoramic image window of the entire dentition including the gum portion is displayed on the upper side of the screen, and a window of the optimized image area Ropt is displayed on the lower side. The optimized image area Ropt can accommodate the focus optimized images Popt1-Poptn of a plurality of partial areas. That is, as will be described later, in the present embodiment, the focus optimization of the partial area is performed a plurality of times to obtain a plurality of focus optimized images. Note that the number of focus optimizations (number of focus optimized images) that can be performed in one interpretation operation may be arbitrary.

  Next, the controller 57 determines whether or not the operator has set the above-described ROI (region of interest) for designating the partial region on the screen using the operation device 58 (step S37). This determination is repeatedly performed until ROI information is given by the operator. When information specifying this ROI is input, the controller 57 displays the ROI superimposed on the panoramic image Ppano (step S38). This ROI is set as shown in FIG. 25, for example. Here, it is represented by a rectangular ROI, but the shape is arbitrary. Also, as shown in FIGS. 26A and 26B, there are various ways of setting the ROI, and attention may be paid to only one tooth, or a setting may be made so as to include a plurality of teeth.

  Further, the controller 57 interactively examines whether or not the set ROI position is acceptable. That is, it is determined whether or not the position is fixed by inputting information on the ROI position determining operation (step S39). If the position is determined (YES in step S39), the image of the determined partial region is enlarged. Whether or not to display is determined from the operation information (step S40). When operation information indicating enlarged display is input (step S40, YES), an enlarged image with a designated enlargement ratio is superimposed on the panoramic image Ppano (step S41). An outline of this enlargement is shown in FIG. When the enlarged display is completed or when the enlarged display is not performed (step S40, NO), the controller 57 then determines whether or not to collect the operation information and stop the ROI designation work (step S41). When canceling, the operator is asked whether or not the focus optimization work for the partial area is to be ended (step S42). When the ROI designation work is stopped but the focus optimization work is not stopped, that is, when the ROI designation work is redone (step S42, YES; step S43, NO), the subsequent processing is returned to step S27. When the focus optimization work is also stopped (step S43, YES), the controller 57 ends the series of processes.

  On the other hand, when the ROI designation work is not stopped (step S42, NO), the partial area designation work is completed, and the area is finally finally determined. In this state, as will be described later, the process shifts to various processes such as focus optimization of a partial region and interpretation using a template.

  On the other hand, when the above-described step S39 is NO, the operator wants to further change the position of the ROI. At this time, information for changing the position of the ROI from the operator is received from the controller 57 via the operating device 58 (steps S44 to S46). In this embodiment, three modes are prepared for this position change. The first mode is a change of the two-dimensional position itself on the panoramic image Ppano. At this time, another designated position of the ROI is accepted as a change position desired by the operator (step S44).

  The second mode is used when the position of the designated ROI is OK, but it is desired to see another parallel cross-sectional position on the front side or the back side (back side) in the depth direction of the dentition. The “depth direction of the dentition” refers to a direction orthogonal to the dentition (that is, a standard surface preset in terms of system). FIG. 28 shows the concept of movement of a partial cross section related to ROI designation in the depth direction Ddp. In this case, a predetermined range in the depth direction in which the gain is measured in advance is designated to be changed by inputting the distance information. For example, distance information such as “5 mm movement” on the back side and “3 mm movement” on the front side when viewed from the front side of the dentition is input.

  Furthermore, in the third mode, the angle of the partial cross section at the position of the designated ROI is to be changed, that is, the cross section designated by the ROI is used as the field of view, but the designated section is inclined while having the field of view. Used when wanting to observe a new section. This tilting process means that the projection direction is changed diagonally by the amount of tilting (rotating) the cross section. The angle for tilting (rotating) is usually several degrees to several tens of degrees.

  FIG. 29 explains the concept of the inclination (rotation) of the cross section designated by this ROI. Note that the inclination of these cross sections is determined by the position of the central axis, the inclination direction, and the inclination angle. For this reason, it can be said that the “inclination” of the cross section is “rotation (rotation)” about the central axis of the cross section, and therefore, the term “inclination” will be represented below. 29 (A) to 29 (C) incline the cross section by a desired angle around the center position, the upper end position, and the lower end position in the vertical direction (Z-axis) direction of the cross section specified by the ROI. Is. In addition, the states shown in FIGS. 29D to 29F are obtained by inclining the cross section by a desired angle with respect to the center position, the left end position, and the right end position in the horizontal direction (x direction) of the cross section specified by the ROI. It is something to be made. The limit for inclining the local cross section designated by the ROI is within the range in the depth direction in which the gain is preset for the cross section. As a result, the meaning of image interpretation comes out.

  Note that when the cross section specified by the ROI is also changed in the depth direction (translation) and it is desired to observe the tilted cross section, the processes of steps S45 and S46 described above are used together.

  When the partial cross section targeted for focus optimization is determined in this way, the controller 57 performs contrast enhancement processing (step S47). This contrast enhancement process may be executed using various conventionally known methods. For example, those described in US Pat. No. 5,467,404 and US Pat. No. 5,960,123 are known.

  Next, the controller 57 performs a focus optimization process on the partial cross-section for which the contrast enhancement process has been completed in the same manner as described above (step S48).

The partial cross-section image that has been subjected to this focus optimization processing (reconstruction) and has improved blur is used as the optimized image, and the position information of the cross-section (the position and angle in the depth direction with respect to the position and angle of the standard cross-section) At the same time, it is displayed superimposed on the original panoramic image Ppano (step S49). This display example is shown in FIG. In the figure, structures such as teeth on the image with optimized focus are displayed using a slightly thicker line, and schematically show that they have been subjected to focus optimization processing. The same applies to other image diagrams.
This optimized image itself exhibits a similar image state of an X-ray transmission image and represents the internal structure of each tooth implanted in the gums. Since the focus is optimized, the structures of the gums and the cross-section of the teeth are depicted with good contrast, and the ability to depict these structures and lesions is also enhanced.

  This optimized image (reconstructed image) of the partial cross section is shown as, for example, in FIG. 31 as a focus optimized image Popt1 in the first area of the optimized image area Ropt in accordance with the drag and drop operation of the operator, for example. (Step S50). When manually pasting in this way, it is up to the operator which region of the optimized image region Ropt to paste. For example, it may be pasted in order from the end region in the focus optimization processing order, or the pasted region may be freely selected with meaning in the optimized image region Ropt.

  Next, the controller 57 determines again from the operation information via the operator's operation device 58 whether or not there is a next ROI designation, that is, a next partial cross-section designation (step S51). When this determination is YES, it is a case where the operator designates a partial cross section to be optimized next, so the process proceeds to step S37 described above.

  On the other hand, when the determination of NO is made in step S51, it is when the designation of the partial cross section and the focus optimization processing for the cross section are finished. An example at this time is shown in FIG. Next, the controller 57 interactively communicates with the operator, and determines whether or not to rearrange images within the same region Ropt of one or more focus optimized images Popt1 to Poptn pasted on the optimized image region Ropt. Judgment is made (step S52). Only when it is determined that rearrangement is desired (step S52, YES), the controller 57 automatically optimizes the optimized image areas of the focus optimized images Popt1 to Poptn in any order or in the ROI setting order according to the manual operation. Rearrangement within Ropt is performed (step S53). This rearrangement process will be further described later.

  Next, the controller 57 determines whether or not to save (store) the focus optimized images Popt1-Poptn pasted in the optimized image area Ropt in the image memory 54 according to the operator information (step S54). If this determination is YES, the storage is executed (step S55).

(Use of 3D templates)
Next, based on information from the operator, the controller 57 determines whether or not to perform interpretation using a template having an array pattern of a focus-optimized image of a partial cross section associated with a medical form (structure) of a dentition. Is determined (step S56). Since this template is different from the conventional one, the inventor calls this template a three-dimensional (3D) template. As described above, the reason why the template is called “three-dimensional (3D)” is that the image information to be pasted is not only a partial cross-sectional image cut out from the panoramic image, but also a standard surface along the dentition. This is because the image information of the partial cross section in the direction (depth direction) orthogonal to is presented together with the position information. The configuration and position of the image such as the arrangement pattern of the 3D template can be freely customized according to the user's preference.

  When the operator instructs to use the 3D template (YES in step S56), it is determined from the operator information whether to use the panoramic image as the background of the 3D template (step S57). When the panoramic image Ppano is not used (step S57, NO), only the 3D template screen is displayed on the screen of the monitor 60. That is, the data of the 3D template is read from the image memory 24, and the 3D template Temp is independently displayed in the area where the panoramic image Ppano has been displayed on the upper side of the screen of the monitor 60 based on the data. At the same time, this and the optimized image area Ropt are divided and displayed. This state is conceptually shown in FIG.

  On the other hand, when a panoramic image is used (YES in step S57), the 3D template screen is superimposed and displayed on the monitor 60 with the previously collected panoramic image as a background. That is, the data of the 3D template is read from the image memory 24, and the 3D template Temp is superimposed on the panoramic image Ppano based on the data, and this and the optimized image area Ropt are divided and displayed (step S59). ). This state is conceptually shown in FIG.

  Next, in response to a command from the operator, the controller 57 pastes the partial images (focus optimized images) Popt1 to Poptn with optimized focus on the 3D template Temp prepared in this way (step S60: FIG. 35, 36). This pasting process will be described in detail later.

  When the pasting is finished, the controller 57 stores the pasted optimized focus images Pop1-Poptn together with the 3D template data in the image memory 24 (step S61). For this reason, the focus optimized images Popt1-Poptn pasted and stored in the 3D template Temp can be immediately read out from the image memory 24 and easily displayed as template stored images as needed next time.

  It should be noted that an image from a separate intraoral X-ray imaging apparatus stored in the image memory 54 is pasted on a part of the 3D template Temp described above, in the same manner as the focus optimized images Popt1 to Poptn. Also good. This pasting control can also be executed under the control of the controller 57.

  (Refocus optimization of panoramic images).

  Further, the controller 57 uses the panoramic image Ppano of the basic standard plane that has already been collected based on the operation information from the operator as the three-dimensional position information of the focus optimized images Popt1 to Poptn as described above. Is used again to determine whether or not to optimize (reconstruct) the entire focus (step S62). This second focus optimization for the panoramic image Ppano is intended to effectively use the position information of the partially-optimized images Popt1 to Poptn. That is, in many cases, the panoramic image Ppano cannot satisfy clinical requirements only by performing focus optimization uniformly along the standard plane. For this reason, there is an intention to provide a panoramic image with less blur as a whole, which is optimized in focus along the actual dentition section corresponding to the individual difference of the subject.

  For this reason, when the determination in step S62 is YES, the processing (reconstruction) for optimizing the focus of the entire panoramic image using the position information of the focus optimized images Popt1 to Poptn is executed again. (Step S63). This second focus optimization will be described later.

  Note that this refocus optimization processing may be executed independently and in combination with the panoramic image Ppano separately from the use of the 3D template Temp. Thereby, the process of semiautomatic optimization focusing can be performed with respect to the whole dentition shown in the panoramic image Ppano. For this reason, it is possible to easily improve the overall defocus of the display structure of the panoramic image Ppano by a relatively simple method. At this time, the greater the number of ROI setting locations and the number of settings, the higher the accuracy of blur removal by optimization.

(Focus optimized image rearrangement process)
In the above-described series of processing of the controller 57, in step S53, rearrangement is performed on one or a plurality of focus optimized images Popt1 to Poptn pasted on the optimized image area Ropt. This process is shown in the subroutine of FIG.

  In this rearrangement process, three rearrangement modes 1 to 3 are prepared. The rearrangement mode 1 is a mode for automatically rearranging according to the attribute of the dentition structure, and the setting method of the attribute can be customized. The rearrangement mode 2 is a mode in which the rearrangement mode 2 is automatically rearranged in the designation order when the ROI is designated for defining the partial region on the basic panoramic image Ppano. Another rearrangement mode 3 is a method for manually operating one or a plurality of focus optimized images Popt1 to Poptn pasted in the optimized image area Ropt according to operation information such as drag and drop from the operator. It can be rearranged arbitrarily.

  Therefore, the controller 57 determines whether the operation information indicates the rearrangement mode = the rearrangement modes 1 to 3 (steps S5301 to S5303).

If it is determined that this is the rearrangement mode 1 (step S5301), the controller 57 uses the three-dimensional position of the partial cross-section that provides the pasted focus optimization images Popt1 to Poptin for the focus optimization. Based on the gain (that is, the three-dimensional distance information from the standard surface), the distance difference from the standard surface is calculated (step S5304). Then, from this distance difference information, the deviation of the sectional posture from the standard plane of each partial cross section (the distance from the standard plane in each depth direction orthogonal to the standard plane and the inclination angle from the standard plane) is recognized, and the deviation. Information is stored (step S5305). FIG. 37 (A) conceptually shows the deviation of the distance from the tooth standard surface, and FIG. 37 (B) conceptually shows the inclination of the angle with respect to the tooth standard surface. FIG. 37C shows a state where the tooth shape is curved with respect to the standard surface. Even in this curved state, the deviation information can be obtained from the gain recognized along the curved surface, and distance information as a function of the position of the curved surface. From these, the focus optimization images Popt1 to Poptn are estimated from which part of the dentition of the subject is collected by referring to a stored table of positions and angles stored in advance (step) S5306). Thereafter, the controller 57 pastes the focus optimized images Popt1 to Poptn within the optimized image area Ropt while automatically rearranging them (step S5307). For example, the image area of the optimized image area Ropt is automatically sorted, for example, from the left side facing the screen, from the back tooth on the right side of the patient to the front tooth, and the back tooth on the left side (for example, by upper and lower dentitions). It is done.

  However, depending on the estimation accuracy of the collection position in the dentition of the focus optimized images Popt1 to Poptn, the order may not necessarily be in order, and in this case, manual rearrangement described later may be performed and rearranged. In any case, according to the rearrangement mode 1, at least most of the rearrangement is automatically performed on the system side. Therefore, the operability is good.

  When it is determined that the rearrangement process is executed in the rearrangement mode 2 (step S5302), the controller 57 reads out the ROI designation order information from the image memory 24 when the focus optimized images Popt1 to Poptn are generated (step S5302). Step S5308). Next, the focus optimized images Popt1-Poptn are automatically rearranged in the optimized image area Ropt so as to be in the specified order from one side, for example, in accordance with the specified order information (step S5309).

  Further, when it is determined that the rearrangement process is executed in the rearrangement mode 2 (step S5302), the controller 57 inputs the order designation information from the operator (step S5310), and the focus optimization images Popt1˜ Poptn is rearranged in the optimized image area Ropt so as to be in the designated order from one side, for example (step S5311).

  As described above, by rearranging the focus optimized images Popt1 to Poptn in any mode 1 (to 3), a certain regularity can be formed in the pasted image group in the optimized image region Ropt. For this reason, when observing the pasted images Popt1 to Poptn in the optimized image area Ropt, it becomes easy to grasp the dentition of the interpreter three-dimensionally, which contributes to the improvement of the efficiency of the interpretation work. In addition, there is an effect that the stored pasted images Popt1 to Poptn are read out and stored again, and are easily organized.

(Focus optimization image pasting process to 3D template)
In a series of processes of the controller 57 described above, in another step S60, a process of pasting one or a plurality of focus optimized images Popt1 to Poptn pasted on the optimized image area Ropt on the 3D template is executed. This process is shown in the subroutine of FIG.

  First, the controller 57 determines whether the operator desires automatic pasting work or manual pasting work from the operation information of the operator (step S6001). If this determination indicates that automatic pasting is desired (YES in step S6001), the controller 57 provides pasted focus optimized images Popt1 to Poptn in the same manner as the above-described calculation method at the time of rearrangement. The three-dimensional position of the partial cross-section is calculated as the distance difference from the standard plane based on the gain used for the focus optimization (that is, the three-dimensional distance information from the standard plane), and the calculated information is primary. Store (step S6001). If this calculation has already been performed at the time of rearrangement, it may be used. And the position in the dentition of the partial cross section which provides the focus optimization image Popt1-Poptn is estimated using this calculation information (step S6002).

  Next, the controller 57 specifies a corresponding image position in the 3D template based on the estimation result (step S6003). The positions of the image regions IM1, IM2,... Constituting the 3D template are visually determined as shown in the upper dentition, the lower dentition, the left posterior teeth, the anterior teeth, the right posterior teeth, as schematically shown in FIG. Are arranged so as to make it easy to grasp the entire dentition structure. For this reason, a correspondence table between the position in the dentition of the partial section providing the focus optimized images Popt1 to Poptn and the image position of the 3D template is stored in advance in the image memory 24 in the form of a storage table, for example. The corresponding image position in the 3D template can be specified by referring to.

  In accordance with this identification result, the controller 57 automatically pastes the focus optimized images Popt1 to Poptin at the corresponding positions of the image regions IM1, IM2,... Of the 3D template (step S6004). Therefore, in the case of this automatic pasting, the screen state shown in FIG. 33 is immediately converted directly to the screen state shown in FIG. 36 (FIG. 33 → FIG. 36).

  On the other hand, when the determination result of step S6001 is NO (manual pasting), the controller 57 performs the processes of steps S6005 to S6008). That is, the controller 57 receives information specifying one of the focus optimized images Popt1 to Poptn from the operator (step S6005), and then receives information specifying a desired image position in the 3D template (step S6005). S6006). For this reason, in response to the operation information from the operator, the controller 57 pastes the designated focus optimized image Popt1 (˜Poptn) to the designated image position IM1 (˜IMn) of the 3D template. The controller 57 determines whether or not the pasting is completed from the operation information, and repeats the processes of steps S6005 to S6007 described above until the operator sets that information interactively. As a result, an image is pasted on the 3D template Temp accompanying a manual operation reflecting the operator's intention.

  In this way, regardless of whether it is automatic pasting or pasting with manual operation, the focus optimized images Popt1 to Poptn can be pasted and stored on the 3D template Temp. As described above, the 3D template Temp can be customized for each dentist or for each dental clinic (hospital), and can be formed as a 3D template Temp having a meaning corresponding to the structure of the dentition at the image position. Yes. Therefore, the focus optimized images Popt1 to Poptn can be stored in an optimized pattern, and the focus optimized images Popt1 to Poptn collected and generated in the past can be read and interpreted more efficiently.

(Refocus optimization process for the entire panoramic image)
In the above-described series of processing of the controller 57, in another step S63, the entire panoramic image functioning as the original image for interpretation based on the positional information of the plurality of focus optimization images Popt1 to Poptn is again subjected to focus optimization. Can be subjected to processing. This process is shown in the subroutine of FIG.

  The controller 57 determines whether or not a plurality of ROIs are set on the panoramic image Ppano and the focus of the partial cross-section image specified by these ROIs is optimized (step S6301). . At this time, the position of each partial cross section may be the same as or different from the position of the standard surface. If the above-described state can be determined, the controller 57 grasps how much the lateral center position of each ROI is deviated from the standard plane and the amount of deviation from the stored gain (step S6302).

  Next, the controller 57 corrects the position of the standard surface using the grasped deviation amount and determines a cross section to be actually optimized (step S6303). At this time, an actual optimized cross section is determined while performing interpolation using a deviation amount derived from the position of the partial cross section (see the waveform DM in the upper part of FIG. 39). Thereafter, the corrected standard plane position information is referred to the look-up table LUT, and the corresponding gain data is obtained as a gain curve (step S6304: (see the middle row in FIG. 39)). Next, the gain curve is integrated to correct the speed curve (step S6305: (see the lower part of FIG. 39)). Further, the previously collected frame data is read (step S6306).

  When preparation is completed in this way, reconstruction is executed using the corrected speed curve and frame data, and the entire panoramic image is generated again as described above (step S6307). The panoramic image is displayed and the data is saved as necessary (step 6308). In this display, the image may be displayed so as to be compared with the first panoramic image.

  As described above, according to the present embodiment, the entire panoramic image is obtained by effectively using the position information of the plurality of focus optimized images Popt1 to Poptn obtained by the ROI setting on the first panoramic image (base image). The contrast can be improved.

  As described above, the digital dental panoramic image photographing apparatus according to this embodiment can provide a panoramic image that sufficiently meets the demands of a dentist, unlike the conventional one.

  Specifically, using the same frame data collected by one imaging, an image obtained by translating a cross-section of a local part to be diagnosed diagnostically or changing the projection direction by tilting (rotation) is used. It can be reconfigured any number of times. The interpretation doctor can quantitatively specify the distance to move the cross section in parallel and the angle to tilt (rotate) it. That is, the image interpretation doctor can move the local cross section interactively while viewing the displayed panoramic image of the standard surface, and observe the image of the tooth or gum on which the cross section is displayed. Thereby, for example, information such as whether the further back side of one tooth hurts or how far the lesion extends to the gum can be obtained three-dimensionally. In addition, the standard plane panorama image that serves as the base image that determines the position of the cross-section of the local part also matches the actual dentition of the subject from several preset standard cross-sections as much as possible. The cross section can be selected as the standard plane.

  For this reason, even if it is important to set the imaging position (cross section) to an optimal cross section along the patient's dentition, it does not need to be so nervous. That is, it is only necessary to select the best one from several types of standard surfaces prepared in advance and start shooting. As described above, the subsequent interpretation can be freely performed using the frame data collected by this photographing. As a result, the operator's burden on the setting of the optimum cross section, which has been pointed out in the past, is remarkably reduced, and the skill level required of the operator is alleviated.

  As described above, the image of the local cross section specified on the panoramic image of the cross section (standard plane) collected with the appropriate optimization and the image of another cross section obtained by repositioning the cross section three-dimensionally are always used. Then, it is reconstructed as an optimally focused image with less blur using a gain that has been measured in advance and stored. Therefore, since there is little blur, the structure information of teeth and gums is abundant and accurate. The diagnosis burden on the dentist is reduced accordingly.

  In addition, an image of a cross section designated by ROI interactively is displayed together with position information. For example, position information indicating that the cross section designated by the ROI is a cross section translated 5 mm behind the standard plane, and the cross section designated by the ROI is on the lower side around an axis passing through the center in the vertical direction. The position information indicating that the section is tilted (rotated) by 20 degrees is displayed. For this reason, the image interpretation doctor can perform image interpretation while grasping the distance (feel) of the internal structure of the teeth and gums. In this way, the interpreting doctor considers individual differences such as the shape of the dentition, “I want to examine the part slightly behind or the front part”, “I want to examine the cross section along the diagonal teeth”, “ `` I want to examine the cross-section along the thickness direction of the tooth '', etc., and can perform cross-section observation that was almost difficult in the past, can obtain more information useful for diagnosis, and the accuracy of diagnosis Greatly contributes to improvement.

  In this way, the internal information of the dentition can be easily and abundantly obtained using the frame data collected in one imaging, so that there is almost no need for another imaging to complement the panoramic image as in the past. Become. Therefore, the time and effort required for diagnosis are reduced, patient throughput is improved, and increase in the patient's X-ray exposure can be suppressed.

  Furthermore, the panoramic image photographing apparatus according to the present embodiment creates an image in which blurring is suppressed as much as possible for part or all of the template image that is digitized and stored, as with the template of the conventional intraoral photographing apparatus, A template image can be created by replacing the image with an image of the intraoral photographing apparatus. Each image cut out from the panoramic image and pasted on the template has a standard plane (a standard tomographic plane set by the trajectory of the apparatus) or a structure that can grasp a deviation (distance) from a desired cross section. This makes it possible to grasp the anatomical structure of the dentition or the positional relationship of parts other than the dentition.

  Moreover, since such a template function can be customized, it can be stored according to the needs of each dental clinic. In addition, since defocusing in the ROI can be suppressed, parts other than the dentition such as the temporomandibular joint, the carotid artery, and the alveolar bone, which have been difficult to handle with conventional panoramic images, can be clearly depicted. For this reason, it is possible to create a template including these image information for management of patient information and store it, and there is a strong possibility that new clinical information such as diagnostic information on temporomandibular disorders, heart disease, osteoporosis and the like can be provided.

  Further, as another aspect, since each ROI image can grasp the deviation amount from the standard tomographic plane or a desired tomographic plane, for example, by estimating and interpolating the deviation amount of the entire panoramic image from the selected ROI image, it is possible to further blur. It is possible to reconstruct a panoramic image that does not exist, and even when only the panoramic image is kept extremely busy, a good image can be provided using the image in the ROI.

  As described above, compared with the conventional template, the present embodiment has a basic difference in that it has a multi-section tomographic function and a pasted image obtained by correcting a blurred image from a panoramic image is pasted on the template.

  As for the control / arithmetic unit 12, another control / arithmetic unit may be used in a stand-alone format or an online format for a portion having a function of post-processing the panoramic image. The controller 57 and the image processor 56 may be executed by the same CPU.

  As another accompanying effect, it is preferable that the effective width (horizontal width) and the position of the detector 32 can be preset from the outside of the apparatus, that is, from the operation device 58. As a result, if the lateral width and position of the detector 32 are controlled equivalently in a place where tooth overlap is observed on the conventional panoramic tomographic orbit, the geometry of the X-ray tube 31 and the detector 32 becomes the tooth shape. By setting the overlap so as to be avoided as much as possible, it is possible to reduce the overlap on the panoramic image of the overlapping portion of the tooth, which has been difficult to diagnose in the past, as much as possible, and also facilitate the diagnosis.

  In the above-described embodiment, the ROI set on the panoramic image Ppano is rectangular as an example, and the ROI is set upright on the image. However, this ROI has an arbitrary shape. Of course, it may be set obliquely. An example of this is shown in FIG. 40A, in which the ROIob is set obliquely in accordance with the tooth form and the like. In this case, the image processor 56 determines a large ROIall having a rectangular shape, for example, including both the oblique ROIob and the ROIn-ob when the oblique ROIob is set upright, as shown in FIG. Let In response to this, the image processor 56 optimizes the largest rectangular ROIall in the same manner as described above, cuts out the oblique ROIob from the optimized image, rotates the image of the oblique ROIob that is cut out, and goes straight upward. ROIn-ob images are obtained as optimized images. As a result, it is not always necessary to set a straight ROI on the upper side. Therefore, even for complicated structures such as the back teeth, it is possible to select only the part to be optimized as much as possible from the beginning and apply it to the optimization. it can.

  It should be noted that the present invention is not limited to the configurations shown in the above-described embodiments and modifications, and can be implemented with appropriate modifications without departing from the spirit of the present invention described in the claims. These modifications are also included in the concept of the present invention.

1 is a schematic perspective view showing an appearance of a panoramic image photographing apparatus according to the present invention. 1 is a schematic block diagram showing an electrical configuration of a panoramic image photographing apparatus according to the present invention. The figure explaining the view of the gain introduced by this invention. The figure explaining the relationship between a dentition and a depth direction. The figure explaining an example of a phantom. The figure explaining another example of a phantom. The figure explaining another example of a phantom. The figure explaining the dentition and the range of the depth direction which sets a gain. The graph which illustrates the speed curve showing the gain introduced by this invention. The figure which illustrates the kind of ROI set on the panorama image of a standard surface. 6 is a schematic flowchart showing a flow of reconstruction of a panoramic image. The figure explaining the superposition addition of several frame data accompanying the reconstruction of a panoramic image. The flowchart explaining the outline | summary of the process of the gain prior measurement which a controller performs. The figure explaining the relationship between the several cross section of a dentition, and the direction (depth direction) which connects an X-ray tube and a detector. The figure explaining the measurement of the optimal gain of each position in each depth direction. The figure explaining the measurement of the optimal gain of each position in each depth direction. The figure explaining the three-dimensional distribution of the gain to measure. The flowchart explaining the outline | summary of the imaging | photography process centering on a controller. The flowchart which illustrates the outline | summary of the interpretation process centering on a controller. The flowchart which illustrates the outline | summary of the interpretation process centering on a controller. The flowchart which illustrates the outline | summary of the interpretation process centering on a controller. The flowchart which illustrates the outline | summary of the interpretation process centering on a controller. The flowchart which illustrates the outline | summary of the interpretation process centering on a controller. The figure explaining the template displayed on a monitor, and its usage. The figure explaining the template displayed on a monitor, and its usage. The figure of the screen which illustrates various ROI designated on a panorama image. The figure of the screen which shows the example of a display of the enlarged view of the part (cross section) of ROI designated on the panoramic image. The figure explaining the concept to translate the cross section by ROI designated on the panoramic image in the depth direction. The figure explaining the concept which inclines (rotates) the cross section by ROI designated on the panoramic image. The figure explaining the template displayed on a monitor, and its usage. The figure explaining the template displayed on a monitor, and its usage. The figure explaining the template displayed on a monitor, and its usage. The figure explaining the template displayed on a monitor, and its usage. The figure explaining the template displayed on a monitor, and its usage. The figure explaining the template displayed on a monitor, and its usage. The figure explaining the template displayed on a monitor, and its usage. The figure explaining the position change of the cross section from a standard surface. The figure explaining an example of the table used for automatic sticking to a template. The figure explaining a mode that the panoramic image is reconfigure | reconstructed again using the positional information on ROI set to the panoramic image. The figure explaining the focus optimization procedure of ROI set diagonally to the panoramic image.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Panorama image imaging device 11 Case 12 Computer 14 Image pick-up part 23 Vertical movement unit 24 Rotation unit 30 Rotation drive mechanism 31 X-ray tube 32 Detector 41 High voltage generator 53 Buffer memory 54 Image memory 55 Frame memory 56 Image processor 57 Controller 58 Controller 60 Monitor P Subject

Claims (9)

An X-ray source that emits X-rays;
A detector that outputs a digital quantity of electrical signals corresponding to incident X-rays at a constant frame rate;
Moving drive means for moving the X-ray source and the detector around the object in a state of being opposed to each other with the object interposed therebetween;
Storage means for sequentially storing, as frame data, electrical signals output by the detector at the frame rate as the movement driving means moves the X-ray source and the detector around the object;
Panorama image generating means for generating a panoramic image of a desired tomographic plane designated in advance based on the frame data stored in the storage means;
Based on the panoramic image data, each of a plurality of designated partial areas of the panoramic image of the desired tomographic plane is in accordance with the position on the space where the X-ray source and the detector are moved by the movement driving means. Partial cross-sectional image generating means for generating a partial cross-sectional image of the optimal focus,
A template comprising a plurality of pasting areas that are two-dimensionally arranged in a predetermined format in association with the attribute of the imaging region of the object, and the plurality of partial cross-sectional images are pasted on the plurality of pasting areas of the template; A panoramic image photographing device comprising: a template processing means for displaying and storing the attached image. The panoramic image photographing device according to claim 1,
The template processing unit is an operation unit that is manually operated, and a pasting process for pasting the plurality of partial cross-sectional images to the plurality of pasting regions of the template according to manual operation information performed on the operation unit. And a panoramic image photographing apparatus. The panoramic image photographing device according to claim 1,
The template processing means recognizes positions of the plurality of partial cross-sectional images in the panoramic image, and displays the plurality of partial cross-sectional images according to the positions recognized by the position recognition means. A panorama image photographing apparatus comprising: an attaching processing unit that automatically attaches to the attaching area of the image processing apparatus. The panoramic image photographing device according to claim 1,
The template processing means stores storage means storing predetermined correspondence information between the plurality of pasting areas of the template and the plurality of partial cross-sectional images pasted to the plurality of pasting areas, and the storage means stores the information. A panoramic image photographing apparatus comprising: a pasting processing unit configured to automatically paste the plurality of partial cross-sectional images to the plurality of pasting regions of the template according to corresponding correspondence information. In the panoramic image photographing device according to any one of claims 1 to 4,
A panoramic image photographing apparatus comprising means for capturing an image photographed by an intraoral X-ray photographing apparatus as an image treated in the same manner as a plurality of partial sectional images generated by the partial sectional image generating means. In the panoramic image photographing device according to any one of claims 1 to 4,
The template processing means includes posture deviation recognition means for recognizing a spatial posture deviation of each of the plurality of partial sectional images from the desired tomographic plane, and information on posture deviation recognized by the posture deviation recognition means. A panoramic image photographing apparatus comprising: a posture deviation information display unit configured to display the information together with each of the plurality of partial cross-sectional images. The panoramic image photographing device according to claim 6,
The posture deviation recognizing means is configured such that, for each of the plurality of partial sectional images, a positional deviation in a parallel direction from the desired tomographic plane, an angular deviation with respect to the desired tomographic plane, and the partial sectional image from the desired tomographic plane A panoramic image photographing apparatus which is means for recognizing information on at least one of the deviations of the entire shape surface. The panoramic image photographing device according to claim 1,
A positional deviation recognizing means for recognizing a positional deviation of two or more partial sectional images of the plurality of partial sectional images generated by the partial sectional image generating means from the desired tomographic plane;
A focal length deviation estimation means for estimating a deviation of the overall focal length of the panoramic image from information on the positional deviation recognized by the positional deviation recognition means;
Panorama image regenerating means for generating a panoramic image of a tomographic plane in which the deviation is corrected based on information on the focal length deviation estimated by the focal distance deviation estimating means from the frame data stored in the storage means; A panoramic image photographing device. A pair of an X-ray source that emits X-rays and a detector that outputs a digital signal corresponding to the incident X-rays at a constant frame rate in a state of facing each other with an object interposed therebetween An electric signal output by the detector at a predetermined frame rate is sequentially stored as frame data by moving around the object, and a desired tomography designated in advance based on the stored frame data. In an image processing method of a panoramic image photographing device that generates a panoramic image of a plane,
Based on the panoramic image data, each of a plurality of designated partial areas of the panoramic image of the desired tomographic plane is in accordance with the position on the space where the X-ray source and the detector are moved by the movement driving means. A partial cross-sectional image of the optimal focus
The plurality of partial cross-sectional images are pasted and displayed and stored in the plurality of pasting regions of the template including a plurality of pasting regions that are two-dimensionally arranged in a predetermined format in association with the attribute of the imaging region of the object. An image processing method for a panoramic image photographing apparatus, characterized by:

Images