JP4861037B2 - Measuring device - Google Patents

Description

  The present invention secures the relationship between intermittent imaging by unifying the coordinate system between a plurality of X-ray three-dimensional (3D) images of the same patient (subject) taken intermittently. The present invention relates to a measuring device.

A conventional X-ray tomography apparatus that images a region of a subject with a visible light imaging unit and positions the region to be imaged with X-rays using the obtained visible light 3D image is disclosed in Patent Document 1, for example. Proposed in
The X-ray tomography apparatus described in Patent Document 1 irradiates X-rays from an X-ray source, and X-ray imaging means for imaging a subject by a detector disposed opposite the X-ray source; A scanner rotating means for rotating the radiation source and the detector around the subject; a subject moving means capable of moving the subject; and a collimator means for variably limiting the X-ray irradiation range. In an X-ray tomographic diagnosis apparatus having an image processing apparatus for generating an X-ray 3D reconstructed image by a reconstruction calculation processing means from a projection image photographed by an X-ray imaging means, the subject placed on the rotating means is imaged The visible light photographing means is further provided, and the image processing apparatus reconstructs a visible light 3D image from the photographing result of the visible light photographing means.

With the above configuration, since it is possible to obtain conversion processing parameters between the coordinates of the X-ray imaging system and the coordinates of the visible light imaging system, positioning using a camera is possible, and as a result, the X of the subject in the scan plan can be obtained. The effect that the radiation exposure can be removed is obtained.
In addition, even when the rotation planes of the X-ray imaging system and the visible light imaging system are completely different, the camera can be used for positioning, so even if the image size of the X-ray imaging system is small, it can be viewed using a wide-angle camera. Since an optical 3D reprojection image can be constructed, it is possible to obtain an effect that the imaging range can be determined without greatly depending on the proficiency of the examiner without depending on experience and intuition.
JP 2005-21661 A

However, in cases such as dentistry that require a long period of treatment, X-ray imaging is intermittently performed on the same subject with different dates and times in order to confirm the course of treatment and treat other teeth. However, in conventional X-ray tomography apparatuses, there is no relationship between intermittent radiographs, and image data obtained by intermittent radiographs considers the positional consistency between images. Therefore, even the same subject does not use a plurality of image data in combination.
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a measurement apparatus that ensures the relevance between intermittent imaging by unifying the coordinate system between a plurality of X-ray images. To do.

  The measuring apparatus of the present invention is installed in the vicinity of an X-ray imaging unit that rotates around the subject to capture an X-ray 3D image, and captures a visible light 3D image of the subject. A measuring apparatus configured to position an X-ray imaging part of a subject to be imaged by an X-ray imaging unit using a visible light imaging unit and a visible light 3D image obtained by the visible light imaging unit, A means for obtaining the anatomical coordinate system of the subject by extracting the feature amount of the imaging region from a plurality of intermittently photographed 3D images of visible light, and visible based on the obtained anatomical coordinate system This is composed of means for unifying the coordinate system between a plurality of intermittently photographed X-ray 3D images by converting the coordinates of the X-ray 3D images photographed simultaneously with the light 3D image.

According to the above configuration, the coordinate system between a plurality of X-ray images taken intermittently with different dates and times can be unified, so that the doctor treating the subject can use the coordinate system of each X-ray 3D image. by comparing the X-ray 3D image based on the, the check before and after surgery, the progress confirmation of correction becomes so easily, whereby the treatment accuracy is significantly improved.
In addition, the coordinate system of the X-ray 3D image with a narrower visual field than the anatomical coordinate system acquired from the visible light 3D image with a wide visual field can be converted, and the X-ray 3D images can be aligned with the obtained coordinate system. Therefore, even an X-ray 3D image taken intermittently with different dates and times can be aligned with high accuracy.

  The measuring apparatus of the present invention generates an anatomical coordinate system from a Campbell plane obtained from a line connecting a plurality of feature points of a subject and a plane orthogonal to the Campbell plane.

  With the above configuration, it is possible to unify the coordinate system with high accuracy by generating the anatomical coordinate system based on the Campbell plane obtained from the lower nose wing point and the left and right outer ear canal of the subject with little change with time. The consistency between the respective X-ray 3D images is improved, and an arbitrary anatomical coordinate system can be selected according to the purpose of diagnosis.

  The measuring device of the present invention reconstructs a visible light 3D image and an X-ray 3D image obtained by photographing a subject, stores them in a storage means, and then generates an X-ray 3D image based on the visible light 3D image read from the storage means at a later date. Is coordinate-transformed to unify the coordinate system between a plurality of X-ray 3D images taken intermittently.

  With the above configuration, even if the image data is stored in the imaging and storage means without taking the anatomical coordinate system into consideration, the image data is read from the storage means at a later date, and coordinate conversion is performed. Coordinate system can be unified.

  According to the measurement apparatus of the present invention, since the coordinate system between a plurality of intermittently photographed X-ray images can be unified, confirmation before and after surgery, confirmation of progress of correction, etc. can be easily performed. The coordinate system of the X-ray 3D image having a narrower field of view than the anatomical coordinate system acquired from the visible light 3D image having a wider field of view can be converted, and the alignment between the X-ray 3D images can be performed using the obtained coordinate system. Therefore, even an X-ray 3D image taken intermittently with different dates and times can be aligned with high accuracy.

An embodiment in which the measurement apparatus of the present invention is applied to an X-ray tomography apparatus will be described in detail with reference to the drawings.
The X-ray tomography apparatus shown in FIG. 1 is a sitting X-ray tomography apparatus for imaging of the head and neck, but a C-arm type X-ray tomography apparatus, an X-ray CT apparatus, and a subject rotation type. It may be an X-ray tomography apparatus or the like.
In FIG. 1, reference numeral 1 denotes an X-ray imaging means. A support arm 1b is erected from the rear surface of a base 1a installed on a floor 30, and is formed in an approximately U-shaped arm shape at the tip of the support arm 1b. The upper portion of the scanner rotating body 1c is rotatably supported.

An X-ray tube 3 for irradiating the subject 2 with X-rays is installed on one end side of the scanner rotating body 1c, and on the other end side facing the X-ray tube 3 across the subject 2, An X-ray detector 4 that detects X-rays irradiated from the X-ray tube 3 toward the subject 2 and transmitted through the subject 2 is installed.
A chair base 1d is provided on the front surface of the base 1a of the X-ray imaging means 1, and the chair 5 is placed on the chair base 1d so that the subject 2 can sit at a position substantially coincident with the scanner rotation center O. is set up.
The X-ray imaging unit 1 is provided on the front surface of the X-ray tube 3, a scanner driving unit 6 that rotationally drives the scanner rotating body 1 c, a chair driving unit 7 that moves up and down the chair 5 on which the subject 2 is seated. The visible light photographing control for photographing the subject 2 by the visible light photographing means 13 by controlling the collimator driving means 8 for driving the collimator 12 and the visible light photographing means 13 comprising the camera installed on the upper part of the collimator 12. An X-ray imaging control means 10 for controlling the X-ray tube 3 and X-ray detector 4 and X-ray imaging of the subject 2 is installed above the visible light imaging means 13. The illumination means 14 for illuminating the subject 2 is installed.

The scanner driving means 6, chair driving means 7, collimator driving means 8, visible light imaging control means 9 and X-ray imaging control means 10 are connected by a cable 16 to an image processing means 20 provided on a console not shown. ing.
The image processing means 20 performs image processing on the visible light image data and the X-ray image data photographed by the scan main body 1 to reconstruct the visible light 3D image and the X-ray 3D image of the subject 2. An interface (I / F) 21 that performs communication between the line imaging unit 1 and the image processing unit 20, a memory 22 that stores image data, and a storage unit 23 such as a hard disk that stores image data necessary for arithmetic processing; , An arithmetic processing means (CPU) 24 for performing arithmetic processing, a display means 25 for displaying a visible light image or an X-ray image, an external input means 26 including a keyboard, and the like.

Next, the operation of the measuring device will be described.
FIG. 2 shows the positional relationship between the X-ray tube 3 provided in the X-ray imaging unit 1, the visible light imaging unit 13 and the illumination unit 14.
When performing X-ray imaging of the subject 2 seated on the chair 5, for example, the X-ray imaging of the head of the subject 2 is performed first, but the visible light imaging means 13 is connected to the X-ray tube. As shown in FIG. 2 (a), the center of rotation 3 of the scanner rotating body 1c substantially coincides with the body axis of the subject 2 is shifted from the focal point 3 by the angle t.
In this state, as shown in FIG. 2B, when the scanner rotator 1c of the X-ray imaging unit 1 is rotated by an angle t, the same image as that seen from the focal position of the X-ray tube 3 by the visible light imaging unit 13 is obtained. It is possible to obtain a visible light image from the rotation angle of, and it is possible to always obtain a visible light 3D image with little shadow by illuminating the subject 2 with the illumination means 14.
Although the illumination unit 14 is provided separately from the visible light imaging unit 13, a ring-shaped illumination unit 14 is provided around the lens of the visible light imaging unit 13 in order to reduce shadows, or illumination composed of a plurality of light sources. By using the means 14, a visible light 3D image with less shading can be obtained.
In photographing a visible light 3D image, the visible light photographing means 13 is synchronized with the rotational angle of the scanner rotating body 1c, and rotational photographing is performed over 360 degrees around the subject 2 to obtain a plurality of angle synchronous rotational photographings. Get an image.

On the other hand, the process of unifying the coordinate system of the visible light 3D reconstruction image obtained in examination 1 and the X-ray 3D reconstruction image of the same subject 2 obtained in examination 2 with different examination dates is shown in FIG. This will be described with reference to the flowchart shown.
In examination 1, visible light rotation imaging including the anatomical reference point of the subject 2 is performed in step S10, and in step S11, visible light 3D reconstruction is performed using the visible light rotation imaging image, and the obtained visible light is obtained. The optical 3D reconstructed image is stored in the storage unit 23.
Next, X-ray simple imaging for positioning is performed in step S12. In step S13, X-ray 3D is performed based on the visible light 3D reconstructed image reconstructed in step S11 and the X-ray positioning image obtained in step S12. An X-ray imaging plan for imaging is performed. This requires three-dimensional positioning for X-ray 3D imaging, but is performed to accurately position a minute target such as a tooth.

In step S14, X-ray rotation imaging is performed based on the X-ray imaging plan, X-ray 3D reconstruction is performed in step S15, and the obtained X-ray 3D reconstruction is all performed together with the visible light 3D reconstruction image in step S16. Are stored in the storage means 23.
In the flowchart shown in FIG. 3, the numbers surrounded by circles indicate that the visible light 3D image and the X-ray 3D image are taken on the same day.
In inspection 2, as in inspection 1, by repeating steps S17 to S22, a visible light 3D reconstructed image and an X-ray 3D reconstructed image are obtained, and all imaging information and feature amount information are obtained in step S23. Save in the storage means 23.

Next, image analysis based on inspection 1 and inspection 2 will be described with reference to the flowchart shown in FIG.
In step S24, the data of the visible light 3D image of examination 1 stored in the storage unit 23 is read out, and the feature amount is extracted. Here, the feature amount is a facial feature point, and the lower nose wing point. Or ear canal.
In step S25, an anatomical coordinate system based on the feature amount is determined. In step S26, the X-ray 3D reconstructed image read from the storage means 23 is subjected to coordinate conversion based on the anatomical coordinate system, An X-ray 3D reconstruction image based on the anatomical coordinate system is obtained.
Similarly, when the X-ray 3D reconstruction image based on the anatomical coordinate system is obtained by repeating steps S27 to S29 for the examination 2, in step S30, the examination 1 and the examination using the same anatomical coordinate system are performed. The X-ray 3D reconstructed image of examination 2 is superimposed on the display means 25, each X-ray 3D reconstructed image is displayed in parallel, or an inter-image calculation is performed between the X-ray 3D reconstructed images. The result is displayed on the display means 25.

FIG. 4 is a flowchart showing details of the processing from step S10 to step S11 in the flowchart of FIG.
That is, in step S41, a visible light object for obtaining a plurality of images without a subject (mask images) by performing rotational imaging with the visible light imaging means 13 while the subject 2 is not sitting on the chair 5 is used. An examiner-less image capturing process is performed. When the mask image is captured, the chair 5 is set in a predetermined position in advance.
The predetermined position can be set at a plurality of locations depending on, for example, the difference in the physique between the child and the adult, and the region such as the head, tooth and jaw, and head.
The imaging range by the visible light imaging means 13 is wider than that of the X-ray projection image, and a wide visual field range including the X-ray projection image can be imaged. This visual field range, that is, the imaging range by the visible light imaging means 13. Can be scaled according to the situation.
Furthermore, it is not necessary to take the above-mentioned visible light subject-free image every time before the subject 2 is photographed, and a rotated image photographed at a predetermined position is stored in the storage means 23 in the image processing means 20. In addition, necessary items may be developed in the memory 22 according to a predetermined position of the chair 5 and used for image processing.

In step S42, the subject 2 is seated on the chair 5 and subject setting processing for moving the position of the chair 5 by the chair driving means 7 is performed according to the physique and part of the subject 2, While the examiner 2 is sitting on the chair 5, the visible light photographing means 13 performs photographing while rotating the scanner rotating body 1c, and a visible light for obtaining a plurality of visible light subject images (live images). A subject image rotation photographing process is performed.
Next, in order to extract only the subject from the live image, in step S43, first, a difference image generation process is performed in which a plurality of mask images and the live image are differentiated for each angle to create an image.
Here, it is preferable that the chair 5 is as small as possible in order to sufficiently obtain an image from the rear of the imaging region of the subject 2. For example, when imaging a tooth jaw part, a headrest and a portion supporting the headrest are It is desirable to reduce the width as much as possible so that the subject extracted image can be sufficiently generated.
More preferably, a more complete subject extraction image can be obtained if the headrest and the portion supporting it are made of a transparent material.
The mask image used here is taken at the same position as the position of each chair in the live image.
If the image obtained by the visible light photographing means 13 is in color, it is mapped in gray scale before performing the difference and converted to monochrome display. However, since the image matrix is 128 × 128 pixels or less, it is large. In the case of the visible light photographing means 13 from which an image matrix is obtained, the pixels are regularly thinned and used.

In step S44, since the background of the chair 5 X-ray detector 4 and the like other than the subject 2 is the same between the mask image and the live image, the pixel values of the background other than the subject 2 are almost the same in these difference images. 0.
For this reason, for example, an area having a pixel value other than ± 20 is extracted as the subject extraction area, the pixel value of the subject extraction area is set to 1, and the background pixel value other than the subject extraction area is set to 0. A contour image is generated.
In step S45, based on the outer contour image, a visible light subject extraction image is generated by extracting only the subject of the visible light subject image obtained by rotational imaging.
Here, the chair 5 is preferably as small as possible in order to sufficiently obtain an image from the rear of the imaging region of the subject 2. For example, when imaging a tooth and jaw, a headrest and a portion supporting the headrest It is desirable to reduce the width as much as possible so that the subject extraction image can be generated sufficiently, and more preferably, the headrest and the supporting portion are made of a transparent material, so that a more complete subject extraction image can be obtained. Is obtained.

In step S46, based on the outer contour image obtained in step S44, a visible light cone beam reconstruction operation by the well-known Feldkamp method is executed in the CPU 24 to generate a visible light 3D reconstructed image, and this visible light 3D reconstruction is performed. The configuration image is stored in the storage unit 23 of the image processing unit 20 shown in FIG.
In step S47, the visible light 3D reconstructed image stored in the storage means 23 is read out to the memory 22, and reprojection calculation is performed in the CPU 24, so that a plurality of visible light subject images are visible light of the 3D reprojected image. Texture mapping is performed on the 3D projection image, a color 3D projection image (visible light 3D projection image) of the subject 2 is generated, and the storage means 23 is stored as individual identification information.
Hereinafter, the reconstructed image basically means a tomographic image of the subject 2, and the reprojected image indicates a 3D image constructed from the reconstructed image. At this time, the contrast and transparency Make adjustments.
Note that, based on the live image and the subject extracted image, a subject extracted live image in which the background of the subject 2 of the live image is replaced with a blue screen or the like may be generated.

FIG. 5 is a flowchart showing details of the processing from step S11 to step S16 in the flowchart shown in FIG.
In step S51, visible light 3D reconstruction is performed, and in step S52, X-ray positioning simple imaging is performed. The X-ray positioning simple imaging data includes the X-ray tube 3, the X-ray detector 4 and the X-ray imaging means in FIG. CB / CTX of 1 and data regarding the internal information of the subject 2 such as the RL direction and the AP direction acquired by X-ray imaging. FIG. 5 shows the data in the RL direction and the AP direction. An X-ray positioning simple image is shown.
Note that, in X-ray positioning simple imaging, information such as bone that is difficult to transmit X-rays is imaged.

In step S53, an X-ray imaging plan is performed based on the visible light 3D imaging data and the X-ray positioning simple imaging data. In the X-ray imaging plan, a plan for determining the imaging position of the imaging target region is made.
FIG. 5 shows a state in which the imaging data and the X-ray positioning simple imaging data in the RL direction and the AP direction are superimposed three-dimensionally.
A plan for determining the imaging position of the part to be imaged is made using both the external information based on the visible light 3D imaging data and the internal information based on the X-ray positioning simple imaging data.
Although details are not shown in FIG. 5, the X-ray positioning simple imaging in step S12 and the X-ray imaging plan in step S53 are simultaneously performed as in the prior art, and the imaging position of the imaging target region is determined. Good.

The examinee 2 is placed on the chair 5 or the bed, and the examiner often performs remote positioning based on experience and performs fluoroscopy. The inspector repeatedly performs fine adjustment while checking the fluoroscopic image. In many cases, the fine adjustment is performed by setting the arm rotation angles of 0 °, 90 °, and 0 ° three times, and seeing them up, down, front, back, left, and right. Adjustment is performed so that a desired area is included in the position and shooting range.
In step S54, X-ray 3D imaging is performed based on the X-ray imaging plan.
The subject is seated on the chair 5, and subject setting processing for moving the position of the chair 5 by the chair driving means 7 is performed according to the physique and part of the subject. While sitting, the X-ray tube 3 and the X-ray detector 4 perform imaging while rotating the scanner rotator 1c to obtain a plurality of X-ray subject captured images.

In step S55, based on a plurality of X-ray 3D images, an X-ray cone beam reconstruction calculation by the well-known Feldkamp method is executed in the CPU 24 to generate a cross-sectional image.
The X-ray 3D imaging data is data relating to internal information of an individual such as a 3D cross-sectional image acquired by CB / CTX imaging of the X-ray tube 3, the X-ray detector 4 and the X-ray imaging means 1 of FIG. 1. .
In addition, in the data regarding the internal information of this individual, in the orthodontic area, the aging of the head is compared, and the cephalogram analysis (cephalogram analysis) used when predicting and treating the growth of the subject is used. Includes necessary data.
In step S56, all the photographing information and feature amount information are converted into a database based on subject information and stored in the storage means 23 or the like.

FIG. 6 is a flowchart showing details of the processing from step S24 to step S26 of the flowchart shown in FIG. 3, and FIG. 7 is a diagram showing an example thereof. In step S61 of FIG. In FIG. 7 (a), the nose wing lower point and the left and right outer ear canal are set as the facial anatomical feature points, and the nose wing lower point is set as the reference plane. A Campbell plane including three points of the left and right outer ear canals is set.
In step S62, feature points are extracted and a face graph is generated and displayed based on the setting. The face graph is a line obtained by connecting various feature points of the face including the set feature points. It is a connection and is a visual representation of feature quantities such as face orientation and distortion.
In step S63, the position of the feature point is adjusted and the reference plane is changed with reference to face graph display and the like. In step S64, a reference plane is generated based on the determined feature point and displayed on the display means 25. .

In the generation of the reference plane, first, as shown in FIG. 7B, a plane (Campbell plane) including three points of the nose wing lower point A, the right outer ear canal B, and the left outer ear canal C is determined. 7C, a plane orthogonal to the Campbell plane and including the right outer ear hole B and the left outer ear hole C is determined.
Further, as shown in FIG. 7 (d), planes orthogonal to these planes and passing through the nose wing lower point A are determined, and the generated three reference planes are displayed.
In step S65, the inclination and position of the displayed reference plane are adjusted or changed, and the anatomical coordinate system based on the three reference planes determined in this way is determined in step S66.
Further, as shown in FIG. 7E, the reference plane may be determined based on a plane including the orbital ear canal line and the interpupillary line obtained from the right outer ear canal B, the left outer ear canal C, and the interpupillary line. It can be arbitrarily selected according to the site and purpose of diagnosis.

In the above embodiment, the visible light 3D image and the X-ray 3D image stored in the storage unit 23 are read out and coordinate conversion is performed. However, as shown in FIG. By converting the coordinates based on the target coordinate system and storing them in the storage means, and performing analysis between images taken by a plurality of examinations, the step of converting the coordinates becomes unnecessary, so that the image analysis can be shortened.
Further, as shown in FIG. 9, coordinate conversion may be performed in the process of reconstructing an X-ray 3D image, and in this case, interpolation processing of the 3D image is not required at the time of coordinate conversion, so that the spatial resolution can be improved. .
8 and 9 are the same as the steps in FIG. 3, and the description thereof is omitted.

It is a block diagram of the measuring device which enforces the coordinate coordinate method of the image which becomes embodiment of this invention. It is explanatory drawing which shows arrangement | positioning of the visible light imaging | photography means with respect to the scanner of the measuring device which implements the coordinate coordinate method of the image which becomes embodiment of this invention, and illumination. It is a flowchart which shows the process of unifying the coordinate system between the images image | photographed by the test | inspection by the measuring device which implements the coordinate unification method of the image which becomes embodiment of this invention. The flowchart which shows the process from the visible light 3D reconstruction and X-ray positioning simple imaging | photography which were image | photographed with the measuring device which implements the coordinate unification method of the image which becomes embodiment of this invention to the preservation | save of all imaging | photography information and feature-value information It is. It is a flowchart which shows the process of the visible light 3D imaging | photography and the visible light 3D reconstruction image | photographed with the measuring device which implements the coordinate unification method of the image which becomes embodiment of this invention. It is a flowchart which shows the process in which an anatomical coordinate system is determined with the measuring device which enforces the coordinate unification method of the image which becomes embodiment of this invention. It is explanatory drawing which shows the production | generation method of an anatomical coordinate system with the measuring device which enforces the coordinate unification method of the image which becomes embodiment of this invention. It is a flowchart which shows the modification of the process which performs coordinate transformation after X-ray 3D reconstruction with the measuring device which enforces the coordinate unification method of the image which becomes embodiment of this invention, and preserve | saves it. It is a flowchart which shows the modification of the process in which a coordinate transformation is performed before X-ray 3D reconstruction by the measuring apparatus which implements the coordinate unification method of the image which becomes embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 X-ray imaging means 2 Subject 3 X-ray tube 4 X-ray detector 9 Visible light imaging control means 10 X-ray imaging control means 13 Visible light imaging means 20 Arithmetic processing means 23 Storage means 25 Display means 26 External input means

Claims (3)

X-ray imaging means for rotating around the subject and capturing an X-ray 3D image of the subject ;
From the X-ray 3D image, which is an image of the subject from the same rotation angle as the image installed near the X-ray imaging unit and viewed from the focal position of the X-ray tube of the X-ray imaging unit Visible light photographing means for photographing a visible light 3D image with a wide field of view ,
Means for extracting the feature quantity of the imaging region from a plurality of visible light 3D images intermittently imaged by the visible light imaging means to obtain the subject's anatomical coordinate system;
Based on the anatomical coordinate system obtained in the means, by the X-ray 3D images together captured with the visible light 3D image coordinate transformation, a plurality of intermittently taken between X-ray 3D image A measuring apparatus comprising: means for unifying a coordinate system. Means for obtaining the subject's anatomical coordinate system include:
The measuring apparatus according to claim 1, wherein an anatomical coordinate system is generated from a Campbell plane obtained from a line connecting a plurality of feature points of the subject and a plane orthogonal to the Campbell plane. Storage means for reconstructing and storing a visible light 3D image and an X-ray 3D image obtained by photographing the subject ;
The unit for unifying the coordinate system between the plurality of X-ray 3D images is configured to coordinately convert the X-ray 3D image based on the visible light 3D image read from the storage unit, thereby intermittently capturing a plurality of images. The measuring apparatus according to claim 1 or 2, wherein a coordinate system between X-ray 3D images is unified.

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