JPH02182240A - X-ray ct apparatus - Google Patents

Abstract

PURPOSE:To enhance throughput and to reduce the load of an operator by detecting the upper and lower limit values of the contour of an examinee in the body axis direction thereof on the basis of a scanning image to store the same and performing control so that the center position thereof is allowed to coincide with the center-of- rotation position of an X-ray imaging mechanism when a slice surface is determined. CONSTITUTION:When an operator operates a slice surface determining means 14 in such a state that a scanning image is displayed on a display means 12 to set a marker M1 at an arbitrary position L1 along a center line L, a control means 13 takes out the upper limit value A1 and lower limit value B1 of the contour of an examinee 3 on said marker M1 on the basis of the data of the preliminarily stored scanning image and calculates the value half the difference D1 between the values A1, B1 as a center position L1. Continuously, an adjusting part 7 is controlled in order to allow the center position L1 to coincide with the center-of-rotation position C of an imaging mechanism to adjust the height position of a top plate 6 and takes the tomographic image of a slice surface. As a result, X-ray absorbing data having no error is obtained and the positioning of the center position L1 and the center-of-rotation position C can be automatically performed and, therefore, an imaging preparatory time is shortened and the throughput of the examinee can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention 1 (Industrial Application Field) The present invention relates to an X-ray zero-stage apparatus that can automatically adjust the height of a subject according to the slice plane to be imaged.

(Prior Art) As shown in FIG. 4, an X-ray CT apparatus includes a bed section 1 that supports a subject 3, and a pedestal section that houses an X@pupil imager side consisting of an X-ray tube 4 and a detector 5. It is composed of 2. The bed section 1 has a top plate 6 that directly supports the subject 3 and is movable in the horizontal direction X.
, is provided with a height adjustment section 7 for adjusting the height position of this top plate 6 in the vertical direction y, and the pedestal section 2 is provided with a dome 8 for guiding the subject 3 moved in the horizontal direction X by the top plate 6. , as shown in FIG. 5, X-rays are irradiated around the subject 3 guided into the dome 8 while the X-ray tube 4 and detector 5 constituting the enemy shadow mechanism are rotated integrally to perform CTfffi. Shadow begins. Part of subject 3 to be photographed (slice surface)
is determined in advance, and it is desirable to perform imaging with the center position of this slice plane aligned with the rotational center position C (FIG. 6) of the imaging mechanism.

Also, when starting such a C-Ding@Shadow, please
Scanogram imaging is performed to determine the slice plane on which the removal should be performed, and the slice plane is determined by observing the scanogram. This scano shooting is
After adjusting the height position of the top plate 6 on which the subject 3 is laid down using the adjustment unit 7, the top plate 6 is moved into the dome 8 of the pedestal unit 2 to take a picture with the subject 3 positioned at a desired position. X-ray exposure is started without rotating the mechanism, and thereafter the subject 3 is moved in the horizontal direction X. 7th
The figure shows an example of a scanogram taken in this manner, and this scanogram was taken by performing X-ray irradiation from the side of the subject 3. In this scanogram, L indicates a center line, and indicates a position midway between an upper limit 3a and a lower limit 3b of the contour along the body axis direction. Since the contour along the body axis is curved, the center line is also curved.

When determining the slice plane on which to perform CTl1t shadowing based on such a scanogram, since the center line of the subject 3 is curved, the rotation center position C of the imaging mechanism and the center are determined depending on the position of the slice plane. It starts to deviate from the line. For example, in Fig. 7, the slice plane perpendicular to position Ll (head) on the center line is closer to the ground than rotation center position C, as shown in Fig. 8 (a), and is perpendicular to position 12 (neck). As shown in Fig. 8(b), the slice plane is located above the rotation center position C. This deviation between the rotation center position C and the center line causes errors in the collected X-ray absorption data. This causes so-called shading, which adversely affects image reconstruction.

In order to eliminate such drawbacks, in the past, the operator controlled the adjustment unit 7 each time according to the slice plane to adjust the height position of the subject 3 to align the rotation center position C and the center line. An operation is performed to match arbitrary positions.

(Problem to be Solved by the Invention) However, adjusting the height position of the subject each time an arbitrary slice plane is imaged increases the time spent preparing for imaging, which reduces the throughput of the subject. There is a problem with doing so. Furthermore, this places a burden on the operator, and there is a risk that an erroneous operation may occur.

The present invention was made in response to the above circumstances.
It is an object of the present invention to provide an X-ray CT apparatus that does not require an operator to adjust the height position of a subject.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides a scanogram photographing means for photographing a scanogram from the side of a subject, and a scanner that captures a scanogram of the subject based on the scanogram. a slice plane determining means for determining a slice plane; and detecting and storing an upper limit value and a lower limit value of the contour along the body axis direction of the subject based on the scanogram, and determining the slice plane when the slice plane is determined. The apparatus is characterized by comprising a control means for controlling the center position to match the rotation center position of the X-ray imaging mechanism.

(Function) A scanogram is taken from the side of the subject, and the upper and lower limits of the contour along the body axis direction are detected and stored in the control means. When the slice plane is determined in this state, the control means calculates the center position of the slice plane based on the upper limit value and the lower limit value, and moves the bed so that this center position coincides with the rotation center position of the X-ray imaging mechanism. control the department. As a result, even if the slice plane changes, the center position is automatically controlled to match the rotational center position of the X-ray imaging mechanism each time. Therefore, the throughput of the subject can be improved, and there is no burden on the operator.

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

FIG. 1 is a block diagram showing an embodiment of the X-ray CT apparatus of the present invention, in which the scanogram imaging means 11 rotates an imaging mechanism consisting of an X-ray tube 4 and a detector 5 as shown in FIG. The subject 3 is moved in the horizontal direction X by the top plate 6.
This is for photographing a scanogram by irradiating the object with X-rays, and in particular for photographing a scanogram from the side direction as shown in FIG. The display means 12 is C
It consists of an RT display, etc., and is for displaying the scanogram. The control means 13 is composed of a microprocessor such as a CPU (Central Processing Element), detects the upper limit value and lower limit value of the contour along the body axis direction in the scanogram, stores these data, and performs processing based on these data. It has a function to calculate the center line. For example, as shown in FIG. 7, the value of the upper limit 3a at position L1 is A1,
If the value of the lower limit 3b is 81, the position L1 is set at a value that is 1/2 of the difference D1 between A1.81. By making similar settings along the body axis direction,
The center line of the curved line will be calculated.

Furthermore, when a slice plane is determined by the slice plane determination means 14 as described later, this control means 13 is configured to match the center position of this slice plane (for example, L1) with the rotation center position C of the X-ray imaging mechanism. perform control operations.

The slice plane determination means 14 consists of a coordinate input device such as a trackball, joystick, mouse, etc. arranged on an operation panel (not shown), and observes a scanogram as shown in FIG. 2 displayed on the display means 12. Marker M for determining the slice plane at an arbitrary position along the center line
Display (Ml, M2).

The adjustment section 7 operates to adjust the height position of the top plate 6 under the control of the control means 13, and this adjustment is performed every time a new slice plane of the subject 3 is determined by the slice plane determination means 14. done automatically.

Next, the operation of this embodiment will be explained.

As shown in FIG.
2, if the operator operates the slice plane determination means 14 to set the marker M1 @ at an arbitrary position L1 along the center line, the control means 13 will set the marker M1@ at an arbitrary position L1 along the center line. Based on the data, the upper limit value At and lower limit value B1 of the outline of the subject 3 on this marker M1 are taken out and A1.

The value of 1/2 of the difference D1 between 81 and 81 is calculated as the center position L1. Subsequently, the control means 13 calculates the calculated center position 1.
The adjustment unit 7 is controlled to adjust the height position of the top plate 6 so that it coincides with the rotation center position C of the photographing mechanism.

Subsequently, the imaging mechanism is rotated and X-ray exposure is started to perform CTlff1 imaging, and a tomographic image on the slice plane is taken as shown in FIG. 3(a).

In this tomographic image, imaging is performed with the center position 1 of the slice plane coincident with the rotation center position C, so that error-free X-ray absorption data can be obtained and shading can be suppressed to a minimum.

Therefore, the influence of shading can be reduced.

Furthermore, since the center position L1 and the rotation center position C can be automatically positioned, the time spent preparing for imaging can be shortened, and the throughput of the subject can be improved. Furthermore, since the burden on the operator is reduced, there is no risk of erroneous operation.

Similarly, in order to shift the slice plane, an arbitrary position L in FIG.
2, the control means 13 uses the same principle to set the upper limit value A2.2 of the outline of the subject 3 on the marker M2. The lower limit value B2 is taken out, and the value of 1/2 of the difference D2 between A2.82 is calculated as the center position L2. Therefore, the control means 13 adjusts the height position of the top plate 6 via the adjustment section 7 so that the center position L2 coincides with the rotation center position C. Subsequently, by performing CTI shadowing in this state, the tomographic image on the slice plane is R shadowed as shown in FIG. 3(b). Also in this tomographic image, since the imaging is performed with the center position L2 of the slice plane coincident with the rotation center position C, the same effect as described above can be obtained.

[Effects of the Invention] As described above, according to the present invention, the center position of an arbitrary slice plane along the body axis direction is calculated based on the contour data of a scanner image taken from the side of the subject in advance. Since this center position is automatically controlled to match the rotation center position of the W&shadow mechanism, it is possible to shorten the time required for shooting preparation, improve throughput, and reduce the burden on the operator. It can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the X-ray CT apparatus of the present invention, FIG. 2 is a side view without showing a scanogram taken by this embodiment, and FIGS. A display example of a tomographic image taken according to the embodiment, FIG. 4 is a perspective view showing an X-ray CT device, FIG. 5 is a side view showing a state in which a subject is placed in the X-ray CT device, and FIG. 6 is an FIG. 7 is a side view showing the pedestal part of the X-ray CT device; FIG. 7 is a side view showing the scanogram in the conventional example;
FIGS. 8(a) and 8(b) are examples of displaying tomographic images in the conventional example. 11... Scanogram photographing means, 12... Display means, 13... Control means, 14...
Slice plane determining means, L... Center line of the scanogram, C... Rotation center position of the imaging mechanism.

Claims (1)

[Claims] In an X-ray CT apparatus in which an X-ray imaging mechanism rotates around a subject and reconstructs an image based on collected X-ray absorption data, a scanogram imaging means captures a scanogram from the side of the subject; a slice plane determining means for determining a slice plane of the subject based on the Scano image; and a slice plane determining means for detecting and storing an upper limit value and a lower limit value of a contour along the body axis direction of the subject based on the Scano image, and determining a slice plane of the subject based on the Scano image; An X-ray CT apparatus characterized by comprising: a control means for controlling the center position of the slice plane to match the rotation center position of the X-ray imaging mechanism when the center position of the slice plane is determined.