JP6690819B2 - Computed tomography equipment - Google Patents

Description

  The present invention relates to a computer tomography apparatus (hereinafter, referred to as CT (Computed Tomography) apparatus) that captures a tomographic image of a subject.

  FIG. 7 is a plan view (A), a front view (B) and a block diagram (C) of a conventional CT apparatus. The block diagram includes a control processing unit P1, an input unit P2, and a display unit P3. A table 5 for placing the subject 3 is arranged between the X-ray source 1 (radiation source) and the two-dimensional X-ray detector 2 (radiation detection means). When a tomographic image of the subject 3 is generated, the X-ray beam B (radiation) is emitted from the X-ray source 1 toward the subject 3, and the rotation axis C of the table 5 on which the subject 3 is placed is rotated. Then, the X-ray detector 2 detects the cone-shaped X-ray beam B transmitted from multiple directions of the subject 3 and collects a large number of transmission images (transmission data). The above operation is called scanning. The collected transmission data can generate a three-dimensional image (a large number of tomographic images) of the subject 3 by a calculation called reconstruction by the reconstruction unit P1-5 (reconstruction means). Usually, a filtered back projection method (FBP (Filtered Back Projection) method) is used for the reconstruction calculation of the tomographic image.

  The table 5 is arranged on a rotating mechanism 6 (rotating means), a lifting mechanism 7 and an XY moving mechanism 8. The rotation axis C of the rotation mechanism 6 intersects the X-ray focal point F of the X-ray source 1 and the scan plane L of the X-ray detector 2. Since the elevating mechanism 7 can move the subject 3 in the vertical direction, the scanning position of the subject 3 can be moved to the scan plane L. The XY moving mechanism 8 can move the rotation axis C of the table 5. The XY moving mechanism 8 can continuously change the imaging distance FCD (Focus to rotation Center Distance) between the X-ray focus F and the rotation axis C. Further, by moving the X-ray detector moving mechanism 9, the detection distance FDD (Focus to Detector Distance) between the X-ray focus F and the X-ray detector input surface D can be continuously changed. In the configuration of FIG. 7, since the imaging distance FCD and the detection distance FDD can be constantly changed, the geometric magnification (= FDD / FCD) can be freely set according to the size and purpose of the subject 3.

  FIG. 8 is a conceptual diagram showing a scan area of a normal scan. An imaging area FOV (Field Of View) of a normal scan is an area that is included in the X-ray beam B about the rotation axis C on the rotation plane (xy plane) and has a thickness in the z-axis direction. It is a cylindrical region. In principle, the shooting area FOV becomes smaller as the geometric magnification increases. In the conventional CT apparatus, the size of the X-ray focal point F is sufficiently smaller than the resolution of the X-ray detector, and therefore, in order to generate a high-resolution tomographic image, the geometric magnification is increased and the imaging region FOV is reduced to perform imaging. To do. That is, in order to accurately image the subject 3, it is necessary to take an image in the imaging area FOV in which the subject 3 fits.

  When the operator accurately scans the subject 3 placed on the table 5, the position designation input unit P2-1 is checked while confirming the transmission image displayed on the transmission image display unit P3-1 (transmission image display means). Then, the elevating mechanism 7 and the XY moving mechanism 8 are moved to move the table 5 to a position where the subject 3 is exactly within the imaging region FOV.

JP, 2002-310943, A JP, 2005-351879, A

  In the conventional CT apparatus, when the subject 3 is just placed in the imaging region FOV, the imaging region FOV cannot be directly known only by the transmission image displayed on the transmission image display unit P3-1 of the display unit P3. It is necessary to perform scanning and position while confirming the tomographic image. In particular, when a part of the subject 3 is scanned in an enlarged manner or the size of the subject 3 is as small as several mm, the imaging area FOV changes greatly only by moving the imaging distance by several mm, so that the positioning is very important. There is a problem that it is difficult.

  In the CT apparatus of Patent Document 1, a temporary scan is performed in a state where the geometric magnification is set low, and an operator designates an ROI (Region Of Interest, a target portion) of an arbitrary portion on the temporarily scanned tomographic image. Although the rotation axis C is positioned so that the ROI-designated portion becomes the imaging region FOV, the operator needs time for temporary scanning and reconstruction of a temporary tomographic image, which is not convenient for usability. .

  Further, in the CT device of Patent Document 2, the photographing area FOV is displayed so as to be superimposed on the outer appearance image photographed by the outer appearance camera 4 (imaging means). However, the imaging area FOV displayed on the outer appearance image is The image pickup area FOV cannot be specified in the first operation because it is determined from the positional relationship between the X-ray source 1, the X-ray detector 2 and the table 5, and then the image pickup area FOV is adjusted to a desired range. Further, FIG. 9 shows an example (A) external appearance display section and (B) front view displayed on the external appearance image display section P3-3 (external image display means) of the display section P3 when the subject 3 is tall. In the figure, since the imaging region FOV is overlapped regardless of the height of the subject 3, the appearance image of the subject 3 displayed due to the angle effect of the light beam K of the lens attached to the appearance camera 4 is the appearance. The part close to the camera 4 is large, and the part far from it is small. Therefore, there is a problem that the area intended by the operator does not always coincide with the area of the tomographic image actually generated.

  Therefore, it is an object of the present invention to provide a computer tomography apparatus that simply and accurately positions the subject 3 when scanning it.

In order to achieve the above-mentioned object, the computer tomography apparatus of the embodiment is a radiation source that emits radiation toward a subject placed on a table, and detects a radiation transmitted through the subject as a transmission image. Radiation detecting means for outputting, rotating means for relatively rotating the table and the radiation with respect to a rotation axis intersecting with the radiation, and a tomographic image of the subject from transmission images detected in a number of directions of the rotation. A computer tomography apparatus having a reconstructing unit that reconstructs an image, displays an image capturing unit that captures the subject from or near the rotation axis, and an external image of the subject captured by the image capturing unit. Appearance image display means, attention portion setting means for setting an arbitrary attention portion on the appearance image of the subject displayed by the appearance image display means, and the attention portion setting hand The target part display means for displaying the range of the target part set on the external image display means, and the target part set by the target part setting means are just included in the tomographic image field of the subject. Transmission image capturing distance calculation means for calculating a transmission image capturing distance between the radiation source and the rotation axis, and the radiation source and the rotation so that the transmission image capturing distance is calculated by the transmission image capturing distance calculation means. The transmission image photographing distance adjusting means for adjusting the distance between the axis and the attention portion display means further includes an edge of the attention portion displayed by the appearance image display means for indicating the top surface and the bottom surface of the subject. Characterized by drawing with one edge .

The (A) top view, the (B) front view, and a block diagram of a CT device which is a first embodiment of the present invention. 6 is a flowchart showing the operation of the shooting distance calculation means in the first embodiment of the present invention. The figure which drew the upper surface ROI and the bottom surface ROI to the appearance image of the to-be-examined object 3 displayed on the appearance image display part P3-3. The (A) top view, the (B) front view, and a block diagram of a CT device which is a second embodiment of the present invention. The flowchart which calculates the moving amount of the xy moving mechanism 5'in 2nd embodiment of this invention. The flowchart which shows the effect | action of 3rd embodiment of this invention. The (A) top view, the (B) front view, and the (C) block diagram of the conventional CT device. The conceptual diagram which shows the scan area | region of normal scan. The example of the (A) external appearance display part displayed on the external appearance image display part P3-3 of the conventional display part P3, and (B) front view.

(Configuration of First Embodiment of the Present Invention)
FIG. 1 is a plan view (A), a front view (B) and a block diagram of a CT apparatus according to a first embodiment of the present invention. To realize this block diagram, a computer such as a general-purpose workstation is used, and it is composed of a CPU, a main memory, a disk, a mechanism control board, a keyboard, a mouse, and a monitor. Note that the same description as above is omitted.

  In FIG. 1, as the X-ray source 1, a microfocus X-ray source in which the X-ray focal point F of the X-ray beam B to be radiated is several to several tens μm is used, and the center of X-ray radiation is in the X-ray detector 2 direction. It is supported by the base 10 so as to face. As the X-ray detector 2, for example, an X-ray flat panel detector (FPD) in which a plurality of X-ray detecting elements are arranged in a two-dimensional matrix is used, and is supported by the X-ray detector moving mechanism 9. Here, the X-ray beam B is the X-ray that is actually measured, and does not include the non-measured X-ray that radiates outside the area outside the X-ray beam B. The irradiation of the X-ray source 1 is performed by the X-ray source control unit P1-1 of the control processing unit P1, and the transmission data of the X-ray detector is collected by the detector control unit P1-2 of the control processing unit P1.

  In FIG. 1, control of the rotating mechanism 6, the lifting mechanism 7, and the XY moving mechanism 8 for moving the table 5 is performed by the mechanism control unit P1-3 of the control processing unit P1.

  The center line CL is defined between the X-ray focal point F and the X-ray detector center Dc in the plan view of FIG. 1A, and the XY moving mechanism 8 of the XY moving mechanism 8 moves so that the rotation axis C moves on the center line CL. Make adjustments. The shooting distance FCD can be changed by moving the rotation axis C. The detection distance FDD can be changed by moving the detector moving mechanism 9. When the operator moves the table 5, the position designation input section P2-1 of the input section P2 is used.

  When the operator scans the subject 3, the scan input section P2-2 of the input section P2 is used. Upon receiving a scan command from the scan input unit P2-2, the scan control unit P1-4 of the control processing unit P1 turns on the X-ray emission ON the X-ray source 1 via the X-ray control unit P1-1 and controls the detector. The X-ray detector 2 is instructed to take in transmission data via the section P1-2, and the rotation of the table 5 is instructed via the mechanism control section P1-3. After the multidirectional transparent data is fetched by the rotation of the table 5, the reconstruction unit P1-5 performs a transparent data reconstruction calculation. The tomographic image generated after the reconstruction can be confirmed on the tomographic image display portion P3-2 of the display portion P3.

  In FIG. 1, an external appearance camera 4 that images the subject 3 from above, an external appearance camera control unit P1-6 that controls the external appearance camera 4, and an external appearance camera imaging unit P2-3 for the operator to issue an imaging instruction to the external appearance camera 4. , An external appearance image display portion P3-3 for displaying an external appearance image captured by the external appearance camera 4, an ROI input portion P2-4 for receiving an ROI input of the displayed external appearance image (an attention portion setting means), and an ROI for displaying the input ROI. A display unit P3-4 (target portion display unit), a shooting distance calculation unit P1-7 (transmission image shooting distance calculation unit) that calculates a shooting distance between the X-ray source 1 and the rotational position from the size of the input ROI. It is a characteristic component.

  In FIG. 1, since the appearance camera 4 and the subject 3 are affected by the light ray angle of the lens of the appearance camera 4, a portion near the appearance camera 4 is large and a portion far from the appearance camera 4 is small. In order to reduce this influence, it is desirable to separate the appearance camera 4 and the subject 3 as much as possible. If the appearance camera 4 and the subject 3 cannot be separated from each other, a mechanism may be adopted in which a mirror is placed on the optical axis of the appearance camera and the light beam is folded back, if necessary.

(Operation of the first embodiment of the present invention)
FIG. 2 shows an imaging distance calculation means for calculating the imaging distance between the X-ray source and the rotational position such that the range included in the ROI drawn by the operator on the appearance image is included in the visual field of the tomographic image. It is a flow chart which shows an operation. A procedure for calculating the shooting distance FCD will be described with reference to FIGS. 1 and 2.

  The ROI drawn on the appearance image is calibrated so that two ROIs showing the top surface (appearance camera 4 side) and the bottom surface (table 5 side) of the subject 3 can be drawn at one time. The table 5 is moved to the lower limit position by the elevating mechanism 7, a dimension jig whose dimensions are known is placed on the bottom surface of the table, and the appearance camera 4 photographs the dimension jig. The dimension jig should be thin so that it is not affected by height. A value obtained by counting the number of pixels of the dimension jig reflected in the external image and dividing by the dimension of the jig is obtained as the bottom pixel size A. Next, the table 5 is moved up to the same position as the scan plane, and similarly, the value obtained by counting the number of pixels of the dimension jig reflected in the external image and dividing by the dimension of the jig is obtained as the pixel size B of the upper surface. .

  When the operator normally inputs the ROI in the appearance image display portion P3-3, the upper surface ROI is set to be drawn, and the pixel size B is divided by the pixel size A into the number of pixels of the circumscribed circle of the upper surface ROI. The number of pixels multiplied by the value is rendered as a circumscribed circle of the bottom ROI. At this time, the shape of the ROI may be not only a circle but also a rectangle or the like, as long as the pixel size B can be changed by the pixel size B divided by the pixel size A.

  After placing the subject 3 on the table 5, the operator uses the appearance camera photographing unit P2-3 of the input unit P2 to instruct the appearance camera control unit P1-6 to photograph the appearance image in step S1. The appearance camera control unit P1-6 takes an image of the subject 3 placed by the appearance camera 4 from above and displays the appearance image on the appearance image display unit P3-3 of the display unit P3.

  In step S2, the operator draws a region to be scanned with the ROI from the appearance image displayed on the appearance image display portion P3-3. The ROI drawn at this time is the top ROI, and the bottom ROI is drawn simultaneously by calculation. In FIG. 3, a top surface ROI and a bottom surface ROI are drawn on the appearance image of the subject 3 displayed on the appearance image display portion P3-3.

The upper surface ROI radius (ROI_R) of the circumscribed circle including the upper surface ROI drawn in step S3 is calculated by the equation (1).
ROI_R = (pixel size B × number of pixels N) / 2 (1)
Here, the number of pixels N is the number of pixels of the circumscribed circle diameter including the upper surface ROI.

In step S4, the photographing distance ROI_FCD after movement is calculated from the calculated ROI_R, the detector distance FDD, and the detector effective width Lw by the formula (2).
ROI_FCD = ROI_R / sin (arctan (Lw / FDD)) (2)

  In the above, the calibration was performed to obtain the pixel size A and the pixel size B, and the upper surface ROI and the bottom surface ROI were drawn. However, a method of drawing without the calibration will be described below.

  Normally, the elevating mechanism 7 is provided with a position sensor such as a linear gauge or an encoder for measuring the position (height) of the table 5, and the position of the table 5 can be grasped. Therefore, the shooting distance, which is the distance from the external camera 4 to the table 5, can be grasped. In addition, since the view angle of the external appearance camera 4 is uniquely determined by the camera lens and the image pickup device provided inside due to the specifications, the view field at the current position of the table 5 can be obtained using this view angle and the shooting distance. When the shooting distance is long, the entire surface of the table 5 is displayed wide, so that the shooting field becomes large (reducing direction in the display of the external image display unit P3-3). Conversely, when the shooting distance becomes short, the shooting field of view becomes large. Becomes narrower (in the enlargement direction in the display of the appearance image display portion P3-3).

  Here, as the upper surface ROI, the ROI on the upper surface of the subject having the maximum allowable height in the specifications when the table 5 is set to the lower limit position is drawn. When the operator draws the bottom ROI at the lower limit position of the table 5 to a desired size, the size of the upper surface ROI of the subject 3 corresponding to the size is calculated from the imaging field of view determined by the imaging distance (known) of the external camera 4. And draw automatically. When the height of the table 5 is at an arbitrary position, the shooting distance is shortened by the distance raised from the lower limit position, the shooting field of view is expanded, and its size is uniquely calculated from the height of the table 5. be able to. When the operator sets the bottom surface ROI on the table surface at the position of the table 5, the upper surface ROI is the size of the ROI on the upper surface of the inspection object having the maximum allowable height in the specifications when the table 5 is at the lower limit position as described above. Is calculated and the upper surface ROI is also drawn.

  In this case, as the table 5 is at the lower limit position, the difference in size between the upper surface ROI and the bottom surface ROI is larger (the upper surface ROI is larger), and as the table 5 is at the upper limit position, the upper surface ROI and the bottom surface ROI are larger. The size is close to the same. The tomographic image of the subject 3 is obtained in the range between the upper ROI and the bottom ROI, and a desired tomographic image can be obtained without calibration.

  In order to obtain a further desired tomographic image regardless of the presence or absence of the above-described calibration, the ROI is set while observing the transmission image of the subject 3 displayed on the transmission image display portion P3-1. The ROI can be set in consideration of the position in the vertical direction. That is, the operator designates the center position of the height at which CT imaging is desired in the transmission image from the side surface of the subject 3 displayed on the transmission image display portion P3-1, and the height of the table 5 at that time determines the appearance camera. If the operator sets the bottom ROI (upper surface ROI) at the position of the table 5 and the center position of the height specified by the operator for CT imaging, the operator wants to perform CT imaging specified by the operator. The size of the upper surface ROI (bottom ROI) at the center position of the height can be calculated and the upper surface ROI (bottom ROI) can also be drawn.

  The ROI displayed on the ROI display portion P3-4 can be more easily understood by the operator by using different colors, thicknesses, and line types. For example, different colors, different line thicknesses, and different line types may be used for the top ROI and bottom ROI.

(Effects of the first embodiment)
According to the first embodiment, if the calculated imaging distance ROI_FCD is in a range that does not interfere with the X-ray source 1 or the X-ray detector 2, the table 5 is moved up to the XY movement mechanism 8 (transmission) to the calculated imaging distance ROI_FCD. Image capturing distance adjusting means). When scanning is performed at the photographing distance ROI_FCD, a tomographic image is generated in the range included in the drawn upper surface ROI.

  Further, since the operator only needs to enclose the ROI on the appearance image of the subject and calculates the amount of movement of the subject where the center of the enclosed ROI and the center of the tomographic image coincide with each other, only the calculated amount of movement is X. The set of the radiation source 1 and the X-ray detector 2 and the subject 3 can be relatively moved to easily move the subject 3 to the center position of the tomographic image.

  Further, since the operator moves only up to the photographing distance ROI_FCD corresponding to the size drawn as the upper surface ROI, the operator draws the ROI without considering the influence of the ray angle, and the subject 3 detects the X-ray source 1 and the X-ray detection. It is possible to avoid collision with the vessel 2.

  In addition, an image of a jig whose dimensions are known is photographed in advance by the appearance camera 4, and the ratio between the size when the jig is on the bottom surface and the size when the jig is on the top surface is obtained and drawn. By simultaneously drawing the bottom ROI and the top ROI having different sizes according to the obtained ratio to the ROI, the ROI including the influence of the height of the subject 3 reflected on the appearance image and the elevation of the table 5 is included. Can be drawn.

  Further, by calculating the imaging distance in which the range included in the upper surface ROI is exactly included in the tomographic image field and moving the rotation axis C to the calculated imaging distance, the positioning time before scanning can be shortened. You can Although the flow of drawing the upper surface ROI has been described, the upper surface ROI may be drawn from the bottom surface ROI depending on the setting.

(Configuration of Second Embodiment of the Present Invention)
FIG. 4 shows (A) a plan view, (B) a front view, and (C) a block diagram of a CT device according to a second embodiment of the present invention. The difference from FIG. 1 is that an xy moving mechanism 5 ′ (moving means) is arranged on the table 5, and a moving amount calculating unit P1-8 (moving amount calculating means) for calculating the moving amount of the xy moving mechanism 5 ′. ) Is added to the control processing unit P1. Further, the center coordinates of the appearance camera 4 are adjusted in advance so as to coincide with the rotation axis of the table 5.

(Operation of the second embodiment of the present invention)
FIG. 5 is a flowchart for calculating the movement amount of the xy moving mechanism 5 ′ so that the center position of the upper surface ROI drawn by the operator on the appearance image matches the center of the tomographic image. Calculation of the amount of movement of the xy moving mechanism 5 ′ in the x and y directions will be described with reference to FIGS. 4 and 5.

  The difference from the operation of the first embodiment is step S7 and step S8. Step S7 is a step of calculating the center coordinates (X_ROI, Y_ROI) of the input upper surface ROI. A circular ROI has center coordinates, and a rectangular ROI has half the diagonal line.

In step S8, the center coordinates (X_ROI, Y_ROI) obtained in step S7, the center coordinates (Xc, Yc) of the appearance image, and the movement amount in the x direction and the movement amount in the y direction from the pixel size B on the upper surface ROI are calculated. Calculate.
Amount of movement in x direction = Xc−X_ROI × pixel size B ... (3)
Amount of movement in y direction = Yc−Y_ROI × pixel size B ... (4)
When the ROI to be drawn is the bottom ROI, the movement amount in the x direction and the movement amount in the y direction are calculated from the pixel size A on the bottom ROI.

(Effect of the second embodiment of the present invention)
If the calculated x-direction moving amount and y-direction moving amount are within the stroke range of the xy moving mechanism 5 ′, the xy moving mechanism 5 ′ moves. Since the set of the X-ray source 1 and the X-ray detector 2 and the subject 3 are relatively moved by the xy moving mechanism 5 ′, the subject 3 is tomographically imaged in a short time only by surrounding the subject with the upper surface ROI. You can move to a central position.

(Configuration of Third Embodiment of the Present Invention)
The configuration of the third embodiment is different in that a moving direction display portion P3-5 (moving direction display means) is provided in the display portion P3 of FIG. FIG. 6 is a flowchart showing the operation of the third embodiment of the present invention, which starts after the end of the flowchart of FIG. The difference is that the current shooting distance FCD and the calculated ROI_FCD are compared in step S9.

(Operation of the third embodiment of the present invention)
In step S9, the moving distance ROI_FCD obtained from the current shooting distance FCD and the ROI radius ROI_RI is compared. If the distance of ROI_FCD is smaller than that of FCD, the table 5 moves to the X-ray detector 2 side, and therefore the moving direction display portion P3-5 of the display portion P3 displays to move to the X-ray detector 2 side. If the distance of ROI_FCD is larger than that of FCD, the moving direction display portion P3-5 displays to advance to the X-ray source 1 side.

(Effect of the third embodiment of the present invention)
Since the operator can confirm the traveling direction of the subject 3 simply by checking the moving direction display portion P3-5, the effect of preventing a collision between the subject 3 and the X-ray source 1 or the X-ray detector 2 is obtained. is there.

F ... X-ray focus,
B ... X-ray beam,
C ... Rotation axis D ... X-ray detector input surface Dc ... X-ray detector center L ... Scan plane CL ... Center line,
K ... Appearance camera lens ray 1 ... X-ray source,
2 ... X-ray detector,
3 ... Subject,
4 ... Appearance camera,
5 ... table,
5 '... xy moving mechanism,
6 ... rotation mechanism,
7 ... Lifting mechanism,
8 ... XY movement mechanism,
9 ... X-ray detector moving mechanism,
10 ... base,
P1 ... Control processing unit,
P1-1 ... X-ray source control unit,
P1-2 ... Detector control unit
P1-3 ... Mechanism control unit,
P1-4 ... Scan control unit,
P1-5 ... Reconstruction unit,
P1-6 ... Appearance camera control unit,
P1-7 ... Shooting distance calculation unit,
P1-8 ... Moving amount calculation unit,
P2 ... Input section,
P2-1 ... Position designation input section,
P2-2 ... Scan input section,
P2-3 ... Appearance camera shooting section,
P2-4 ... ROI input section,
P3 ... Display,
P3-1 ... Transmission image display unit,
P3-2 ... tomographic image display unit,
P3-3 ... Appearance image display section,
P3-4 ... ROI display section,
P3-5 ... Moving direction display

Claims (4)

A radiation source that emits radiation toward a subject placed on a table, a radiation detection unit that detects the radiation transmitted through the subject and outputs it as a transmission image, and a rotation axis that intersects the radiation. In a computer tomography apparatus having a rotating unit that relatively rotates the table and the radiation, and a reconstructing unit that reconstructs a tomographic image of the subject from transmission images detected in multiple directions of the rotation,
A photographing means for photographing the subject from the rotation axis or the vicinity thereof;
An appearance image display means for displaying an appearance image of the subject imaged by the imaging means,
Attention portion setting means for setting an arbitrary attention portion on the appearance image of the subject displayed by the appearance image display means,
A target portion display means for displaying the range of the target portion set by the target portion setting means on the appearance image display means,
Transmission image capturing distance calculation means for calculating a transmission image capturing distance between the radiation source and the rotation axis so that the target portion set by the target portion setting means is exactly included in the tomographic image field of the subject. ,
Transmission image capturing distance adjusting means for adjusting the distance between the radiation source and the rotation axis so that the transmission image capturing distance calculated by the transmission image capturing distance calculating means is obtained;
The computerized tomography apparatus according to claim 1, wherein the target portion display means further draws an edge of the target portion displayed by the appearance image display means with two edges indicating a top surface and a bottom surface of the subject . The computer tomography apparatus according to claim 1 ,
A transmission image display means for displaying the transmission image;
A computer tomography apparatus for setting the part of interest of the subject from the appearance image displayed by the appearance image display means and the transmission image displayed by the transmission image display means. The computer tomography apparatus according to claim 1 or 2 ,
Movement amount calculation means for calculating the movement amount of the subject so that the center position of the portion of interest matches the center of the tomographic image,
A computer tomography apparatus having a moving unit that relatively moves the set of the radiation source and the radiation detector and the subject so that the moving amount is calculated by the moving amount calculating unit. The computer tomography apparatus according to any one of claims 1 to 3 ,
A computer tomography apparatus having moving direction display means for displaying a moving direction of the table operated by the transmission image photographing distance adjusting means.

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