JP4594783B2 - Cone beam X-ray CT imaging system - Google Patents

Description

  The present invention relates to an improvement in positioning of an imaging part of a cone beam X-ray CT imaging apparatus.

  More specifically, a subject to be imaged by each subject at the time of CT imaging using a small-field cone beam X-ray in which the irradiation area of the cone beam X-ray is reduced in order to reduce the X-ray exposure amount of the subject. The present invention relates to improvement of preliminary photographing means for improving positioning accuracy for each region (region of interest).

  2. Description of the Related Art Conventionally, a head and neck cone beam X-ray CT imaging apparatus intended for a dental region sandwiches a subject's head and hangs down from a swivel drive unit as disclosed in Japanese Patent Laid-Open No. 2000-139902. An X-ray generator, an image intensifier with a 4-inch effective field of view, and an X-ray detector composed of a camera system are arranged opposite to each other on both ends of the swivel arm. A device that irradiates a portion of interest in the head and neck region including the tooth and jaw region with a small-diameter cone beam X-ray and performs image processing on the data transmitted through the subject to obtain a CT image. A local irradiation X-ray CT imaging apparatus is known that performs imaging only by rotation without moving, and performs imaging of a cylindrical range having an image reconstruction range of approximately φ38 mm × H29 mm obtained by one imaging.

  According to Japanese Patent Laid-Open No. 2002-219127, an X-ray detector comprising an image intensifier with a 4-inch effective field of view and a camera system is used in the same manner as the above-described device, and the swivel arm can be adjusted as necessary during imaging. A reconstructed image at the time of X-ray CT imaging by continuously moving an appropriate amount continuously, for example, along the dental arch in the horizontal direction orthogonal to the opposite axis of the subject while the rotation axis rotates. A panoramic X-ray CT imaging apparatus capable of obtaining a wide range of reconstructed image areas extending over all dentitions including the temporomandibular joint by one imaging is known in addition to a cylindrical shape with a range of φ42 mm × H40 mm. The feature of these apparatuses is that the X-ray exposure dose of the subject for one imaging is small.

  On the other hand, according to Japanese Patent Laid-Open No. 2003-175031, in addition to the above-described apparatus, an image receiving apparatus including a 9-inch or 12-inch image intensifier and a camera system is used, and a wider range including a tooth jaw region is reproduced. An apparatus capable of obtaining a constituent image area is also known. In the case of this apparatus, the reconstructed image area is generally a medical device when an image receiving device including a 9-inch image intensifier and a camera system is used. A variable field of view of the technique used is adopted, and the reconstructed image area has a maximum effective field of view in the range of φ150 mm in the panorama mode, φ102.4 mm in the implant mode, and φ51.2 mm in the dental mode. The image receiving device further comprises a 12-inch image intensifier and a camera system. In the case of using, the reconstructed image area can be obtained as a maximum effective field of view in the range of φ190 mm in the panoramic mode, φ150 mm in the implant mode, and φ100 mm in the dental mode. It is supposed to be possible. The feature of this device is that it has a variable field of view compared to the previous two models. It has been pointed out that while the reconstructed image area can be obtained widely, the X-ray exposure dose to the subject per radiograph increases considerably in proportion to the size of the reconstructed image area. In recent years, an X-ray generator and a device capable of varying the image receiving device with respect to the center of the pivot axis of the pivot arm have been proposed at both ends of the pivot arm. However, there is a problem that the installation space of the apparatus is greatly expanded and cannot be effectively used.

  Further, according to Japanese Patent Application Laid-Open No. 2004-275512, in an X-ray CT apparatus for rotating and irradiating a subject with an X-ray beam and taking a projection image thereof, the X-ray beam arranged so as to sandwich the subject. And an X-ray generating means for generating the X-ray, and a rotating shaft for rotating the X-ray generating means and the X-ray detecting means with the subject interposed therebetween, wherein the rotating shaft is provided on the floor side of the apparatus. An X-ray apparatus is disclosed.

  The above-mentioned two have the great advantage that the X-ray exposure dose to the subject is small because the imaging area is small, while the imaging target region is at the imaging center, that is, the turning center position of the X-ray source and the image receiving device. There are drawbacks that are difficult to position. On the other hand, in the latter case, as described above, the reconstructed image area can be obtained widely, so that the above positioning is easy, but in proportion to the size of the reconstructed image area, the subject per photographing However, there is a drawback that the X-ray exposure dose is considerably increased. Moreover, it can be said that the apparatus of Unexamined-Japanese-Patent No. 2004-275512 is an apparatus proposed in order to solve problems, such as safety | security of an interference with respect to the subject of the apparatus disclosed by Unexamined-Japanese-Patent No. 2003-175031, installation space, etc. .

In order to maximize the diagnostic effect by minimizing the X-ray exposure dose to the subject, it is necessary to reliably capture all of the subject's imaging target region (region of interest) into the imaging area. In particular, when the image reconstruction range obtained by one imaging is a cylindrical range of about φ38 mm × H29 mm, or the reconstruction image range is a cylindrical range of φ42 mm × H40 mm (dental imaging mode), the limited X Since there is only a radiation irradiation area, positioning the subject's imaging target area (region of interest) so that it is well-balanced can place a considerable burden on the operator and at the same time greatly affect the diagnostic ability. Some have pointed out the possibility of re-shooting.
In order to improve the operability for this positioning, in the above-mentioned apparatus of Japanese Patent Laid-Open No. 2002-219127, by selecting an imaging target region (region of interest) before CT imaging for this positioning, An X / Y moving mechanism for moving in the horizontal direction with respect to a standard position preset for each imaging target part in advance as standard, and its control means are provided, and the imaging (rotation) center position of the apparatus ( After moving the center of the image reconstruction area), perform pre-photographing for the radiographing target region (region of interest) from the front and side by spot radiography or simple radiography, and display the image on the monitor. By checking the positional relationship in the image reconstruction area of the displayed region to be imaged (region of interest) and aligning the center position cursor on the monitor to the center of the region to be imaged (region of interest) Te, move the photographing (rotation) center position of automatic devices to position the cursor is instructed, is provided preliminary imaging means for correcting, it is known that it is subjected to the market.
JP 2000-139902 A JP 2002-219127 A JP 2003-175031 A JP 2004-275512 A

  However, in the method of the preliminary imaging means using the simple imaging described above, there is originally a limited X-ray irradiation area when the reconstructed image range is a cylindrical range (dental imaging mode) of φ42 mm × H40 mm. Therefore, in addition to the fact that it is difficult to put the imaging target part (region of interest) of each subject in that area, in addition to the fact that the hard tissue part exists symmetrically, especially in the tooth jaw region, In the case of this type of cone beam X-ray CT imaging apparatus in which X-rays are incident on the imaging target region (region of interest) from the horizontal direction, the opposite tooth, temporomandibular joint, or peripheral tooth overlaps. In many cases, it is difficult to specify the central part of the region to be imaged (region of interest) even in the images displayed on the monitor for the molar portions 5 to 8 and the temporomandibular joint portion. Some cases depend on the degree of experience There was people there pointed out, and the like.

  In view of such a current situation, the present invention takes advantage of the great advantage that the X-ray exposure dose to the subject is small because the imaging area is small in a small irradiation field, that is, X is the imaging center of the imaging target region (region of interest). Positioning the center of rotation of the radiation source and the X-ray detector (the center of the image reconstruction area) corrects the aforementioned position by appropriately combining conventional methods without changing the mechanism of the apparatus. Is to provide a preliminary photographing means that is accurate and greatly improved.

 (1) In order to achieve the above-described problems, the present invention sets a plurality of standard positions of each imaging target region (region of interest) of the subject in advance by setting a preliminary imaging mode in the imaging mode. The set standard position data means, the imaging part selection means for specifying an arbitrary imaging target part (region of interest), the position of the imaging target part (region of interest) selected by the imaging part selection unit, and the swivel arm The X and Y movement mechanism for automatically moving in the horizontal direction in order to match the turning center position of the swivel axis, the control means thereof, and the imaging of the subject positioned by the head fixing device at the time of imaging A plurality of tomographic image data obtained by performing imaging similar to CT imaging in an extremely narrow angle range from a plurality of directions is superimposed on the imaging target region (region of interest) selected by the region selection unit by image processing. A layer photographing means, a display means for displaying the image on the monitor, and a center position cursor at the time of photographing on the monitor of the display means while confirming the displayed photographing object part (region of interest) from the plurality of directions, Preliminary imaging means for correcting the position by automatically matching the turning center of the pivot axis of the swivel arm with the center position of the imaging target region (region of interest) by matching the center of the displayed imaging target region (region of interest) It is solved by providing.

 (2) Further, a tomography unit that performs imaging similar to CT imaging in a very narrow angle range from a plurality of directions, after the rotation center coincides with the imaging target region (region of interest) of the subject, CT imaging similar to CT imaging in a narrow angle range from two directions, ie, a substantially front direction of the region to be imaged (region of interest) parallel to the midline of the subject and a substantially lateral direction orthogonal to the median line is performed. The image processing is performed by superimposing a plurality of obtained image data, and while confirming the imaging target region (region of interest) from the two directions displayed on the monitor, the center position during imaging on the monitor By aligning the cursor, the imaging (rotation) center position of the device automatically aligns the center position of the imaging target region (region of interest) indicated by the cursor with the turning center of the turning axis of the turning arm, and an image reconstruction area In the middle of This is solved by providing preliminary imaging means for accurately correcting the position of the center of the imaging target region (region of interest) at the center.

(3) Further, the above-described XY movement mechanism and its control means are configured to turn the swivel arm, that is, the swivel axis of the swivel arm with respect to the center of the imaging target region (region of interest) selected by the imaging region selection unit. This is solved by moving the center so that the center portion of the standard position of the selected imaging target region (region of interest) matches the turning center position of the turning axis of the turning arm.

  (4) Further, the XY movement mechanism and the control means described above select the imaging target part (subject side) selected by the imaging part selection means with respect to the turning center of the turning axis of the turning arm. This can be solved by matching the center of the standard position of the selected imaging target region (region of interest) that is moved with the turning center position of the turning axis of the turning arm.

  (5) Further, the above-described X / Y movement mechanism and its control means move the rotation center of the turning axis of the turning arm to either X or Y, and the imaging target part (subject side). The center portion of the standard position of the imaging target region (region of interest) selected by the combination with the means for moving to either X or Y is made to coincide with the turning center position of the turning axis of the turning arm. Is solved.

 (6) A plurality of pieces of image data obtained by photographing at a narrow angle where the photographing angle of the tomographic means for performing the same photographing as the CT photographing in the narrow angle range is limited to a range of 3 ° to 10 °. The effect of tomography can be fully enjoyed by superimposing. Of course, the above-mentioned angle can be achieved by setting the angle to 10 ° or more, but an increase in the imaging angle becomes a factor that leads to an increase in the X-ray exposure of the subject. The above X-ray exposure should be avoided.

  In the conventional method of preliminary imaging means by fluoroscopic imaging and spot imaging, originally, when the reconstructed image range is a cylindrical range (dental imaging mode) of φ42 mm × H40 mm, there is only a limited X-ray irradiation area. In addition to the fact that it is difficult to put the imaging target part (region of interest) of each subject in that area, in addition to the fact that the hard tissue part exists symmetrically, especially in the tooth and jaw region, it is common In the case of this type of cone beam X-ray CT imaging apparatus in which X-rays are incident on the imaging target region (region of interest) from the horizontal direction, the teeth on the opposite side, the temporomandibular joint, or the peripheral teeth in the image The degree of overlap is severe, and it is often difficult to identify the central part of the region to be imaged (region of interest) even in the images displayed on the monitor for the molars 5-8 and the temporomandibular joint. Cases that depend on the degree of experience Although there were many indications, according to the present invention, an imaging target region that is considered to be particularly difficult to position, by appropriately combining conventionally used tomography techniques without changing any mechanism of the apparatus By performing tomography at an extremely small angle with respect to the image, the degree of overlapping of the teeth on the opposite body side, the temporomandibular joint, or the teeth on the peripheral part in the image described above is greatly reduced due to the effect of tomography. Utilizing the great advantage that the X-ray exposure dose to the subject is small due to the small imaging area in the irradiation field, and the imaging center of the region to be imaged (region of interest) and the rotation center position of the X-ray source and receiver Positioning with the center of the image reconstruction area became easy, and the operability for the operator was remarkably improved.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIGS. 1A and 1B are external views showing an embodiment of a panoramic X-ray CT imaging apparatus disclosed in Japanese Patent Laid-Open No. 2002-219127. FIG. ) Is a partial cross-sectional view of the external side surface, and FIG. In the figure, a rotary drive unit 2 supported on a support frame 1 includes an X / Y axis table, a control motor for the X / Y axes, a control motor for rotating the swivel arm 3, and a swivel. It is composed of main parts such as a slip ring contact for realizing multi-rotation of the arm 3. The swivel arm 3 hanging from the rotary drive unit 2 is provided with an X-ray source 4 and an X-ray detector 5 facing each other at both ends thereof. As will be described later, the revolving arm 3 is provided with a safety sensor for preventing subject interference on the lower surface thereof. The subject positioning chair portion 6 can move up and down as known in the art, and the subject head positioning head positioning device 7 includes a vertical actuator, a horizontal swing positioning mechanism, a longitudinal adjustment mechanism, a chin rest, a subject It consists of the main parts such as the front / rear positioning light beam irradiating means for instructing the front tooth reference position, the temporal pressing mechanism, and the fixed belt, and the vertical actuator is vertically moved separately from the chair portion 6 as indicated by the arrows as a whole. It is possible to move. In addition to the individual mechanisms of the head positioning device 7 and the light beam means described above in the drawing, the center line of the subject provided on the rotary drive unit 2 supported by the support frame 1 is light-transmitted. The center-confirmation light beam 8 indicated by the beam, the center of the subject's imaging target region (region of interest) provided on the swivel arm 3, that is, the swivel arm rotation center and at the same time the vertical direction of the image reconstruction range A tomographic position confirmation light beam 9 indicating the center from three directions and an up-and-down positioning beam irradiation means 10 indicating respective limit positions in the up-and-down direction of the image reconstruction range are provided. Conventionally, in general, a panoramic X-ray imaging apparatus or a Cephalo X-ray imaging apparatus is used in the dental area, and various CT apparatuses, MRI apparatuses, etc. are used in the medical area. It will not be described in detail for the application of. Further, the X-ray detector 5 is an I.D. It is not limited to I, CCD, etc., and it is known that a two-dimensional sensor such as TFT is used.

  FIG. 2 shows several examples of plan views of the reconstructed image range of a cone beam X-ray CT apparatus being used in the dental area. First, FIG. 2 shows the cone beam used in the dental area. FIG. 1A is a schematic diagram of CT imaging. FIG. 1A shows an X-ray source 4 and an X-ray centered on a rotation center O using an X-ray cone beam 4a having an imaging target region (region of interest) 3 as an irradiation range. The rotation center of the swivel axis of the swivel arm 3 on which the detector 5 is opposed is fixed and swiveled 180 ° or 360 ° to take a picture. The reconstructed image range obtained by processing the captured and stored image data has a spherical shape of φM shown in the figure. FIGS. 2B and 2C are schematic diagrams in the dental CT imaging mode, in which an X-ray cone beam 4a having an imaging region 3 ′ as an irradiation range is used and the rotation center is fixed around the rotation center O. In the plan view and the side view in the case of taking an image of 180 ° or 360 °, the reconstructed image range in this case is a cylindrical shape having a diameter M × height H, where H is the height. Next, FIG. 3 is a schematic diagram in the panoramic CT imaging mode, and shows a case where a wider area is continuously photographed in a panoramic manner using an X-ray cone beam in a limited irradiation field. Rotation drive control from the start of imaging to the end of imaging with respect to the imaging region or range set by the imaging mode setting means with the rotation center of the turning axis of the turning arm 3 as the center from the X-ray irradiation start position The rotation angle range necessary for the photographing is swung by the means, and the range set while sequentially moving the rotation center of the turning arm 3 along the photographing trajectory 11 set in advance by the photographing mode setting means during the turning. It shows that shooting is performed. FIG. 8 shows an example of the image reconstruction range in each shooting mode.

  Next, specific examples of the present invention will be described in detail with reference to FIGS. 4 (a) and 4 (b) and FIG. First, the standard position data means 13 in which a plurality of standard positions of each part to be imaged (region of interest) are set in advance, and the part to be imaged (region of interest) is selected by the imaging position selection unit 14 (not shown) before imaging. The X (Y) movement mechanism for moving in the horizontal direction with respect to the standard position preset for each imaging target region in advance as standard, and the imaging (rotation) center position of the apparatus with its control means After moving (the center of the image reconstruction area) to the region to be imaged (region of interest), the tomographic position confirmation light beam 9 irradiated from three places on the lower surface of the swivel arm is used as in the conventional case of FIG. Check the position and correct it. The light beam 9 is irradiated with two light beams 9a and 9b that are irradiated so as to overlap the X-ray irradiation width direction center line from the X-ray source side and the X-ray detector side toward the rotation arm rotation center; The light beam 9c irradiated perpendicularly to this, and the center of the imaging target region (region of interest) of each subject when the rotation arm rotation center is in the dental CT imaging mode, It is necessary to correct the position by checking whether the center of the image reconstruction range is instructed or whether the imaging start position in the block CT imaging mode or panoramic CT imaging mode is in an appropriate position. In this case, the operation BOX is used to automatically move the X and Y in the horizontal direction in order to make the turning center position of the turning axis of the turning arm coincide with the center of the subject imaging region (region of interest). Move Structure and to correct the position by using the control means. Further, the positional confirmation in the vertical direction and the correction of the position with respect to the subject are performed by two light beams emitted from the vertical positioning beam irradiation means 10 indicating the respective limit positions in the vertical direction of the image reconstruction range. The position correction in the height direction is provided in the chair portion 6 for positioning the subject and the head positioning device 7 for positioning the subject head as shown in FIG. This can be done by moving up and down individually in the direction of the arrow using the vertical actuator.

  Next, pre-imaging for position correction using the tomography method according to the present invention, particularly when accurate position correction is required due to the small reconstruction range as in the dental CT imaging mode. An example of the means is illustrated in FIG. The preliminary imaging unit 12 specifies a standard position data unit 13 in which a plurality of standard positions of each imaging target region (region of interest) of the subject M are set in advance, and an arbitrary imaging target region (region of interest). The X-ray source 4 and the X-ray detector 5 are arranged so as to face each other at the standard position S of the imaging target region selected by the imaging region selection unit 14 and the rotation axis of the revolving arm 3. Is automatically moved by a conventionally known XY movement mechanism and its control means, and the X-ray source 4 and the X-ray source 4 with respect to the region to be imaged about the turning center O. While the line detector 5 is turning through the turning arm 3, for example, as shown in the figure, the region between Pa and Pb is photographed while irradiating ± 2 ° X-ray with respect to the center line from the side surface direction. After turning without irradiating X-rays during Pc, again from the front direction Serial performs the same irradiated while taking between Pc~Pd X-rays. This two-way imaging is not 180 ° or 360 ° imaging, but CT imaging (tomographic imaging) in a very narrow angle range, for example, normal CT imaging performed at a frame rate of 60 frames / second, 10 seconds / 1 rotation. It is carried out by partial use of. Accordingly, in the case of 360 ° shooting, 600 frames of image data are fetched because both the shooting angle and the shooting time are small. In this case, about 6 frames of image data are fetched. The image data captured in this way is not used by image processing but only one central part, and by superimposing a plurality of front and rear images with the central part as a reference, the tomographic effect causes the image of the image on the opposite side or the peripheral part. Overlap is significantly improved. The image from the two directions is displayed on the monitor shown in FIG. 6, and the center position cursor at the time of photographing on the monitor is displayed at the center while checking the displayed image of the region to be photographed (region of interest) from the two directions. The position of the rotation axis of the swivel arm is automatically moved to the position of the center of the object to be imaged (region of interest) indicated by the cursor. Move the swivel center. It should be noted that the imaging angle with respect to each imaging target region (region of interest) is advantageous if imaging from a direction substantially parallel to the subject's midline and a direction orthogonal thereto is possible, but is not specified.

  FIG. 7 shows another embodiment, in which the XY movement mechanism and its control means are selected by the imaging part selection means with respect to the turning center of the turning axis of the turning arm. The case of the apparatus characterized by moving a site | part (subject side) is shown. Further, in the X-ray CT apparatus for rotating and irradiating the subject with the X-ray beam and taking a projection image thereof, the X-ray that generates the X-ray beam arranged so as to sandwich the subject is interposed therebetween. The present invention can also be applied to a generator provided with a rotating shaft that rotates the generating means and the X-ray generating means and the X-ray detecting means with the subject interposed therebetween, and the rotating shaft is provided on the floor side of the apparatus.

  The image of the region to be imaged (region of interest) displayed in this way is significantly overlapped with the opposite side or the periphery due to the effect of tomography, compared to the conventional method using simple imaging from two directions. As a result, it becomes easy to identify the center of the region to be imaged (region of interest), and as described above, the region to be imaged (region of interest) of each subject having only a limited X-ray irradiation area can be identified. In addition to being difficult to enter the area itself, hard tissue parts exist symmetrically, especially in the tooth and jaw region, and generally X-rays are incident on the region to be imaged (region of interest) from the horizontal direction. In the case of this kind of cone beam X-ray CT imaging apparatus, the degree of overlap of the teeth on the opposite body side, the temporomandibular joint, or the peripheral part in the image is severe. Is the image displayed on the monitor However, it has been pointed out that it is often difficult to specify the center of the region to be imaged (region of interest), and there are many cases that depend on the degree of experience of the operator. According to the technique using tomography, since the target region (region of interest) can be easily confirmed based on the tomographic image displayed on the monitor, the center position suitable for each subject (i.e., image reconstruction) Since the center position cursor on the monitor can be accurately moved to the center of the area to be captured and displayed at the center of the range (region of interest), the cursor automatically moves to the position where the cursor has moved. After the position of the rotation center of the swivel arm is corrected more accurately by the rotation drive control means, sufficient diagnostic information expected and necessary by the operator can be obtained by performing CT imaging of the part. Shooting is possible To become.

  As described above, the preliminary imaging means of the present invention is a preliminary imaging means based on a new idea that makes the most of the features of the cone beam X-ray CT imaging apparatus without changing the configuration of the conventional apparatus. Rather than performing fluoroscopic imaging from multiple angles or spot imaging by simple imaging, each imaging target region (region of interest) is selected for each imaging target region (region of interest) of the selected subject. The X-ray exposure dose to the subject is suppressed as much as possible by performing CT imaging (tomographic imaging) in a limited narrow angle range from multiple directions, and the reconstructed image range of the imaging target area as in the conventional dental imaging mode However, when there is only a limited X-ray irradiation area that has only a cylindrical area of φ42 mm × H40 mm, for example, it is difficult to put an individual subject's imaging target region (region of interest) into that area. In this type of cone beam X-ray CT imaging apparatus in which X-rays are generally incident on an imaging target region (region of interest) from the horizontal direction in addition to the existence of a hard tissue portion symmetrically as in an area. In the case of preliminary shooting by simple shooting, the teeth on the opposite side, the temporomandibular joint, or the teeth on the periphery are projected and imaged, so the molars 5-8 and the temporomandibular joint are displayed on the monitor While it was pointed out that it was difficult to specify the center of the region to be imaged (region of interest) in many of the images, and there were many cases that depended on the level of experience of the surgeon. Because of the effect of tomography by adopting preliminary imaging, the degree of overlap of teeth on the opposite side, temporomandibular joints, or peripheral teeth in the above-mentioned image is greatly reduced. The X-ray exposure dose to the examiner is low Taking advantage of the great advantage, it becomes easy to correct the positioning of the imaging center of the region to be imaged (region of interest) and the rotation center position of the X-ray source and X-ray detector (center of the image reconstruction area). Therefore, it can be said that this is a pre-photographing means in which operability is remarkably improved. FIGS. 10 and 11 (a) to 11 (d) are hard copies of an image photographed by the conventional method and an image photographed by the method of the present invention for reference.

Example 3 external view Some examples of top view of reconstructed image range of cone beam X-ray CT apparatus Schematic diagram in panoramic CT mode Example of preliminary imaging using tomography, and example of tomographic position confirmation light beam and vertical positioning beam irradiation means An example of standard position data means An example of position correction using the center position cursor during shooting on the monitor Front and side views of other embodiments Plan view of an embodiment of a reconstructed image range by photographing mode Configuration diagram of main part of cone beam X-ray CT apparatus according to the present invention Hard copies of images taken with conventional methods and techniques of the present invention Hard copies of images taken with conventional methods and techniques of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Support frame 2 Rotation drive unit 3 Turning arm 4 X-ray source 5 X-ray detector 6 Chair part 7 Head positioning device 8 Midline confirmation light beam 9 Tomographic position confirmation light beam 10 Vertical positioning beam irradiation means 11 Imaging trajectory 12 Preliminary imaging means 13 Standard position data means 14 Imaging region selection means

Claims (2)

A chair (6) for a subject (M), a head positioning device (7) for positioning the subject (M), and a cone beam X-ray ( 4a) an X-ray source (4) capable of irradiating, an X-ray detector (5) for detecting the cone beam X-ray (4a) transmitted through the subject (M), and the X-ray source at one end A swivel arm (3) having the X-ray detector (5) opposed to the other end of (4), a rotation drive unit (2) for rotating the swivel arm (3), and the swivel arm (3 ) In the horizontal direction, and the swivel arm (3) rotates about the swivel axis as the swivel center (O), thereby imaging the subject (M) In a cone and beam X-ray CT apparatus for head and neck that performs X-ray CT imaging of a region,
Standard position data (13) in which a standard position (S) for each imaging target part is set in advance;
An imaging region selection means (14) for selecting the imaging object region;
A plurality of pieces of image data are captured while rotating the turning arm (3) in an angular range of 10 ° or less around the turning center (O), and the turning points ( Tomographic imaging means for obtaining a tomographic image centered on O);
Display means for displaying the tomographic image obtained by the tomographic image photographing means,
The center of rotation (O) is moved to the center of the standard position (S) of the region to be imaged selected by the region to be imaged selecting unit (14), and tomography is performed by the tomographic image capturing unit from a plurality of directions. The tomographic image from the plurality of directions obtained by the tomography is displayed on the display means, and the swivel is performed based on a central part of the imaging target region in the tomographic image displayed on the display means. The center (O) is moved from the center of the standard position (S) to the center of the imaging target region, and the position of the turning center (O) is corrected for the X-ray CT imaging. Cone beam X-ray CT system for head and neck. 2. The cone-beam X-ray CT apparatus for a head and neck according to claim 1, wherein the tomography by the tomographic imaging unit is performed from two directions of a front direction and a side direction of the subject (M).

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