JP2015223459A - Method for reducing motion artifact in dental tomography apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of preventing image quality reduction and re-imaging due to a motion artifact generated with the body motion of a subject in a dental X-ray CT apparatus.SOLUTION: A dental X-ray imaging apparatus which includes an X-ray source, X-ray imaging means, a rotation arm integrally supporting the X-ray source and the X-ray imaging means so as to be opposed to each other around a subject, rotation means for rotating the rotation arm and an apparatus frame supporting the rotation means comprises: a process A of installing a 3D scanner capable of real-time scan to acquire 3D data of the face with the 3D scanner at the time of imaging start; a process B of acquiring 3D data of the face with the 3D scanner at all times during CT scan with X-ray; and a process of correcting reconstruction calculation of projection data acquired with X-ray CT scan in accordance with the positional change of the face on the basis of the information obtained with the 3D scanner in the process A and the process B.

Description

  The present invention relates to a method for reducing motion artifacts in a dental tomography apparatus.

  Conventionally, as a method for reducing motion artifacts, there is an X-ray imaging apparatus described in Japanese Patent Laid-Open No. 2006-61501 (Reference 1). This X-ray imaging apparatus has an X-ray source that emits X-rays toward an imaging region of a subject, an X-ray detection unit that detects X-rays transmitted through the imaging region, and the X-ray source and the X-ray detection unit that face each other The X-ray source and the X-ray detector are rotated by the drive motor 74 so that the X-ray source and the X-ray detection unit rotate around the object while facing each other. Is to do.

  This X-ray imaging apparatus is provided with a drive change detection device that detects an external force that prevents the turning arm from turning, and when the drive change detection device detects a force that prevents the turning arm from turning, The turning drive is stopped and the X-ray irradiation is stopped. That is, when an external force is applied to the turning arm, the turning of the turning arm and the X-ray irradiation are stopped to prevent the creation of a defective X-ray image. I am doing so.

JP 2006-61501 A

Data Design Co., Ltd. Catalog 3D Design-Scanning- "Atrec 3D Scanners"

  In the X-ray imaging apparatus described in the above-mentioned patent document, any of the X-ray source and the X-ray detection unit held facing the turning arm hits the subject's shoulder or the like during X-ray imaging and rotates. Only when it is blocked, the turning of the turning arm and the X-ray irradiation are stopped, the body movement of the subject itself is detected, and the turning of the turning arm and the X-ray imaging are not stopped.

Further, as the 3D scanner itself, a 3D scanner (ArtecEva ^™ (registered trademark)) manufactured by Artec Group Inc. capable of high-speed continuous shooting of 15 shots per second has already been developed.

  An object of the present invention is to provide a method of preventing image quality degradation and re-imaging due to motion artifacts caused by body movements of the subject himself / herself in the dental X-ray CT apparatus with such a 3D scanner.

  In order to solve the above-described problems, the motion artifact reduction method of the dental X-ray CT apparatus according to the present invention detects an X-ray source that irradiates an X-ray toward the subject and an X-ray that has passed through the subject. X-ray imaging means, a turning arm that integrally supports the X-ray source and the X-ray imaging means around the subject, a turning means for turning the turning arm, and the turning means In a dental X-ray CT imaging apparatus in which a 3D scanner capable of real-time scanning is installed in a dental X-ray imaging apparatus including a device frame that supports the apparatus, a process A for acquiring facial 3D data with the 3D scanner at the start of imaging From the information obtained from the process A and the process B obtained by the 3D scanner and the process B obtained by the 3D scanner at all times during the X-ray CT scan, the process B Depending on 置変 reduction, characterized in that a step of performing reconstruction correction operation of the projection data obtained by X-ray CT scan.

  Also, the motion artifact reduction method of the dental X-ray CT apparatus of the present invention makes it possible to stop the CT scan immediately when an uncorrectable facial position change occurs.

  Furthermore, the motion artifact reduction method of the dental X-ray CT apparatus of the present invention can wear a position data marker that can be fixed to a portion of the facial muscles where the movement of the muscle is small.

  Thus, according to the present invention, it is possible to prevent image quality deterioration due to motion artifacts caused by body movement, to prevent the need for re-photographing, and to reduce exposure due to unnecessary scanning. Can do.

It is a block diagram for demonstrating the motion artifact reduction method of this invention dental X-ray CT apparatus. It is a side view for demonstrating the motion artifact reduction method of this invention dental X-ray CT apparatus. It is a top view for demonstrating the motion artifact reduction method of this invention dental X-ray CT apparatus.

  Hereinafter, embodiments of the present invention will be described in detail.

  In the present invention, an X-ray source that irradiates the subject with X-rays, an X-ray imaging unit that detects X-rays that have passed through the subject, and the X-ray source and X around the subject. Real-time scanning is possible for a dental X-ray imaging apparatus comprising a swivel arm that integrally supports a line imaging means, a swivel means for swiveling the swivel arm, and a device frame that supports the swivel means In a dental X-ray CT imaging apparatus in which a 3D scanner is installed, the process 3A acquires facial 3D data with the 3D scanner at the start of imaging, and always acquires facial 3D data with the 3D scanner during X-ray CT scanning Projection data acquired by X-ray CT scanning according to the position change of the face from the process B and the information obtained from the process A and the process B obtained by the 3D scanner. Providing a step of correcting the configuration operation.

  The present invention will be described with reference to the drawings. First, a position data marker that can be fixed to a portion where the subject's muscle movement is small is worn. This position data marker, for example, sticks a black colored sticker on the patient's forehead. In addition, it can replace with a colored seal | sticker and can also be set as a protrusion-shaped seal. Moreover, a headband shape may be sufficient. As shown in FIG. 1, an X-ray source 2 that emits X-rays toward the subject, an X-ray imaging means 3 that detects X-rays that have passed through the subject, and the X around the subject. A turning arm 4a for integrally supporting the radiation source 2 and the X-ray imaging means 3 facing each other, a turning means 4 for turning the turning arm, and an apparatus frame (not shown) for supporting the turning means 4 In particular, a 3D scanner 10 capable of scanning in real time is mounted in the vicinity of the X-ray source 2.

  Next, 3D data of the face is acquired by the 3D scanner 10 at the start of photographing, and this data is supplied to the 3D image memory 11 through the third on / off switch 29 in the on state, and then supplied to the display device 20. And display. Thereafter, the third switch 29 is turned off, the fourth on / off switch 30 is turned on, a CT scan by X-ray is performed, and the 3D scanner 10 constantly acquires facial 3D data during this CT scan, The 3D data is supplied to the display device 20 via the fourth switch 30 and displayed.

  In the display device 20, 3D data acquired at the start of imaging and stored in the 3D image memory 11 via the third switch 29 and 3D always obtained during the X-ray CT scan that is always supplied via the fourth switch 30. Compare the data and monitor changes in facial position.

At this time, the following processing is performed using position information of the 3D data of the face acquired at the start of imaging and the 3D data of the face acquired during the X-ray CT scan.
(a) The incident angle of the X-ray with respect to the imaging region of the subject is calculated according to the change in the facial position using the principle of the triangular lateral distance. The respective incident angles are calculated from the 3D data of the black mark portion of the face acquired at the start of imaging and the 3D data of the face black mark portion acquired during the X-ray CT scan. Back projection processing is performed on the projection data acquired by the CT scan so as to correct the difference in incident angle, and the reconstruction calculation is performed.
That is, the X-ray projection data acquired during the CT scan is calculated by the incident angle difference as if the X-ray from the X-ray source was projected onto the position data (position data before the position change) acquired at the start of imaging. The movement is corrected and back projection processing is performed to perform reconstruction calculation.
(b) If the facial position change that cannot be corrected in the method (a) occurs, the CT scan is immediately stopped.

For the detection of the position information, it is desirable to use a position data marker at a portion where the movement of the muscles of the face of the subject is small. Further, as shown in a side view in FIG. 2 and a top view in FIG. 3, for example, with a device such as a headband having a black position detecting portion supported by the temporal region of the subject attached, the scan However, the movement of the headband position can also be used.
It should be noted that it is also possible to detect a part of the facial muscle of the subject whose facial muscle movement is small as the facial positional information without using the position data marker.

Processing of the CBCT image and panoramic image obtained by the X-ray CT scan is performed as follows.
In the present invention, the X-ray imaging data stored in the large-capacity frame storage means 6 is supplied to the CBCT image processing means 16 via the second switch 8 when obtaining a CBCT image, and image processing is performed here. The image is supplied to the processed image storage means for CBCT 17 and further supplied to the output means 19 via the image display storage means for CBCT 18 so as to obtain a desired CBCT image.

  The X-ray imaging data stored in the large-capacity frame storage means 6 is supplied to the panorama image processing means 12 via the first switch 7 when a panoramic image is to be obtained. The image data is supplied to the large-capacity processed image storage means 13 and further supplied to the output means via the entire image display storage means 14 so as to obtain a desired panoramic image.

  In the example described above, the 3D scanner is used to display the face of the subject. However, the present invention is not limited to this, and any means that can acquire three-dimensional coordinates can be used. Can do.

DESCRIPTION OF SYMBOLS 1 Subject 2 X-ray source 3 X-ray imaging means 4 Turning means 5 A / D conversion means 6 Large-capacity frame image storage means 7 1st on / off switch 8 2nd on / off switch 9 Prosthesis 10 3D scanner 11 3D image memory 12 Panorama image processing means 13 Large-capacity processed image storage device 14 All image display storage means 15 Output means 16 CBCT image processing means 17 CBCT processed image storage means 18 CBCT image display storage means 19 Output means 20 Display Means 24 Third switch 25 Fourth switch

Claims (3)

  An X-ray source that irradiates the subject with X-rays, an X-ray imaging unit that detects X-rays that have passed through the subject, and the X-ray source and the X-ray imaging unit that face each other around the subject A 3D scanner capable of real-time scanning is installed in a dental X-ray imaging apparatus comprising a swivel arm that supports the swivel arm integrally, a swiveling means for swiveling the swivel arm, and a device frame that supports the swivel means In the dental X-ray CT imaging apparatus, the process A for acquiring facial 3D data with the 3D scanner at the start of imaging, and the process B for acquiring facial 3D data with a 3D scanner at all times during an X-ray CT scan, From the information obtained from the process A and the process B obtained by the 3D scanner, the reconstruction calculation of the projection data obtained by the X-ray CT scan is corrected according to the change in the facial position. Motion artifact reduction method of a dental X-ray CT apparatus characterized in that a Cormorant process.   2. A method of reducing motion artifacts in a dental X-ray CT apparatus, comprising: immediately stopping a CT scan when a facial position change that cannot be corrected occurs in claim 1.   A method for reducing motion artifacts in a dental X-ray CT apparatus, characterized in that a position data marker that can be fixed to a portion of the facial muscle where movement of the muscle is small can be worn.

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