JPH0312136A - X-ray ct instrument - Google Patents

Abstract

PURPOSE:To miniaturize an X-ray CT instrument and to exclude uneasiness from an object by arranging the object so as to be rotatable between an X-ray tube and an X-ray detector, which are respectively fixed, and executing CT photographing. CONSTITUTION:An X-ray tube 10 and a two-dimensional X-ray detector 11 are respectively faced and fixedly provided and between them, an object supporting means 12 is arranged so as to be rotatable and vertically moved. Then, the object 1 is supported and the object supporting means is controlled by a driving part 15. Thus, since the fixed X-ray detector is irradiated with X rays from the fixed X-ray tube and the object is scanned while rotating the object by the object supporting means which is provided between the X-ray tube and X-ray detector, the need for a rotary photographing mechanism is eliminated and the configuration of the device is simplified. Then, the need for a slip ring is also eliminated and further, the scan can be executed by supporting the object in a sitting state. Since it is not necessary to stay the object in a dome, the psychological uneasiness is not applied to the object.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention (Field of Industrial Application) The present invention relates to an X-ray CT apparatus that reconstructs an image based on X-ray projection data.

(Prior Art) As an example of an X-ray CT apparatus, a structure as shown in FIG. 8 is known. An X-ray tube 2 and an X-ray detector 3 are arranged with the subject 1 to be photographed sandwiched between them, and the X-ray tube 2 irradiates the subject 1 with X-rays while integrally working with the X-ray detector 3. By rotating, X-ray projection data of the subject 1 is detected by the X-ray detector 3 . By reconstructing these X-ray projection data, a tomographic image of an arbitrary slice plane of the subject 3 can be obtained and used as diagnostic information. X
The line detector 3 is composed of a one-dimensional detector in which a large number of unit detection elements are arranged in the rotation direction.

As shown in FIG. 9, the configuration of these X-ray CT apparatuses is roughly divided into a bed section 4 that supports the subject 1 and a pedestal section 5 that houses an imaging mechanism.

The bed section 4 supports the subject 1 on the top plate 6 and adjusts it to a desired height in the vertical direction using the height adjustment table 7, and then moves the top plate 6 horizontally to support the subject 1. It is guided into the dome 8 of the pedestal section 5.

After positioning the part of the subject 1 to be imaged on the X-ray irradiation axis l connecting the X-ray tube 2 and the X-ray detector 3,
X-ray irradiation is started while rotating the ray detector 3 around the subject 1.

When scanning with X-rays to take a tomographic image of an arbitrary slice plane of a subject, the imaging mechanism including the X-ray tube 2 and the X-ray detector 3 is usually rotated once (one scan).
By doing so, one tomographic image is obtained. It is possible to photograph different slice planes by moving the top plate 6 and shifting the subject to change the positioning region.

When performing such imaging, it takes 1 to 6 seconds per scan, and multiple times the time is required to perform multiple scans. In addition, the focus size of the X-ray tube 2 is small, about 1 on x 1 mm, and in order to obtain a sufficient amount of X-rays with such a small focus size, a rotating anode type suitable for this is mainly used as the X-ray tube 2. It is being

(Problems to be Solved by the Invention) Conventional X-ray CT apparatuses have the following problems.

1. It requires a rotating imaging mechanism consisting of heavy parts including an X-ray tube, an X-ray detector, etc., and is structurally thick (1) It is heavy and expensive.

2. A complicated slip ring is required to transmit signals to rotating parts during continuous rotation, which is expensive.

3. A bed section on which the subject lies is required, which occupies space, making it impossible to downsize the apparatus.

4. The subject must be kept in the dome of the gantry during X-ray photography, which causes great anxiety to the subject psychologically.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an X-ray CT apparatus with a novel configuration that can solve the conventional problems.

[Configuration of the Invention (Means for Solving the Problem) In order to achieve the above object, the present invention reproduces an image based on X-ray projection data obtained by irradiating X-rays from the circumferential direction of the subject. The constituent X-ray CT apparatus includes an X-ray tube and an X-ray detector that are each fixedly provided, and a subject support means that is rotatably provided between the X-ray tube and the X-ray detector. This is how it was done.

(Function) While irradiating X-rays from the fixed X-ray tubes toward the X-ray detector, scanning is performed while rotating the subject using the subject support means provided between the two. Therefore, since a rotating photographing mechanism is not required, the configuration of the apparatus becomes simple. Additionally, a slip ring is no longer required, and scanning can be performed by supporting the subject in a sitting position rather than lying down. Furthermore, since the subject is not kept in the dome, psychological anxiety is no longer caused.

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

FIG. 1 is a configuration diagram showing a first embodiment of the X-ray CT apparatus of the present invention, in which an X-ray tube 10 and a two-dimensional X-ray detector 11 are fixedly provided facing each other.

The two-dimensional X-ray detector 11 is composed of a well-known scintillator or the like, and is configured to be able to detect X-ray projection data in the two-dimensional directions of the X direction and the X direction, as shown in FIG.

A subject support means 12 is arranged between the X-ray tube 10 and the X-ray detector 11 so as to be rotatable and movable up and down.
is supported, and this subject support means 12 is controlled by a drive section 15. In addition, the X-ray tube 10 and the subject support means 12
A collimator 13 is provided between the X-ray tube 10 and the X-ray tube 10. This collimator 13 has a plurality of slits 13a, 13b, 13c along the body axis direction Z of the subject 1 as shown in FIG.

..., and irradiates the subject 1 with X-rays as parallel beams for each slit. As a result, when the subject 1 is irradiated with X-rays, slice planes corresponding to the number of slices can be simultaneously imaged. At this time, the slice thickness is, for example, 5 mm.

The number and size of the X-ray detectors 11 in the y direction are such that X-ray projection data corresponding to the slice thickness W can be detected, and as shown in FIG. 2, lla is the first slice surface,
11b is a second slice plane, 11C is a third slice plane, etc., and is configured to detect X-ray projection data. Further, a second collimator 14 is provided between the subject support means 12 and the X-ray detector 11, and this second collimator 14 has a structure similar to that of the collimator 13. It is arranged so that the parallel beam of X-rays that have passed through 1 can pass through it as is. The collimator 14 functions so that the X-ray projection data transmitted through the subject 1 is detected by the X-ray detector 11 without being affected by scattered radiation. However, this second collimator 14 is not absolutely necessary.

The subject support means 12 is driven at a rate of, for example, 5 to 10 seconds/rotation, and one scan is completed every time it rotates. Further, the subject support means 12 is driven so as to be capable of tilting over an angle θ, as shown in FIG.

By performing a tilt operation, the angle of the slice plane can be changed.

The X-ray tube 10 has a long focal point size in the y direction of the X-ray detector 11 (that is, in the body axis Z direction of the subject 1).
A collimator 13 (with a pitch W of 5 mm) as described above is used.
) when performing one scan through
It becomes possible to photograph the sliced surface. In addition, since the X-ray tube 10 of the present invention requires a long time for one scan,
In other words, since it is sufficient to drive the subject support means 12 slowly at the above-mentioned rate without performing high-speed rotation as in the conventional rotating imaging mechanism, the amount of X-rays is small and the rotating anode type is not used (the fixed anode type is used). Also, this X-ray tube 1
By using a grounded anode type as shown in FIG. 5, the cooling method can be simplified because the anode is at O potential.

The two-dimensional X-ray projection data for each slice plane detected by the X-ray detector 11 is stored in the data acquisition unit 16, and then reconstructed by the reconstruction unit 17, so that the two-dimensional X-ray projection data for each slice plane is A tomographic image of is displayed on the display unit 18. The system control unit 19 is in charge of overall control and performs necessary control operations each time.

Next, the operation of this embodiment will be explained.

Assuming that the collimators 13 and 14 are set to a pitch W of, for example, 5 -, and the X-ray tube 10 is one that has a focal point that is long in the body axis Z direction of the subject 1, for example, 1 mm x 50 -, The subject 1 is supported on the subject support means 12 and is irradiated with X-rays by the X-ray tube 10 while being driven at a rate of, for example, 10 seconds/rotation. Thereby, the X-ray detector 11 simultaneously detects X-ray projection data of ten slice planes each having a different slice thickness of 5 mm along the body axis Z direction of the subject 1. Since 10 tomographic images can be simultaneously captured by one scan of 10 seconds, the scanning time for each image is 1 second. X
X for each slice plane detected by the line detector 11
The line projection data is sent to the reconstruction unit 17 via the data collection unit 16.
After the image is reconstructed, it is displayed on the display section 18.

According to this embodiment, by simply rotating the subject support means 12 that supports the subject 1 with the X-ray tube 10 and the X-ray detector 11 fixed, a plurality of different images can be obtained in one scan. A tomographic image for each slice plane can be photographed simultaneously, and for example, ten slice planes can be photographed simultaneously as described above. As the subject support means 12, a subject chair commonly used in medical examinations can be used, and as the drive unit 15 for driving the chair, a commonly used combination of motors, gears, etc. can be used. This can be easily realized by a mechanism. That is, the drive unit 15 may have a mechanism that can rotate at a slow speed so as not to place a burden on the subject 1 that may cause dizziness or the like.

Therefore, there is no need for a complicated mechanism for rotating the rotating photographing mechanism at high speed as in the past. Therefore, the configuration of the device can be simplified, and costs can be reduced. Furthermore, since a slip ring with a complicated structure for signal transmission is also not required, costs can be reduced. Furthermore, since the subject 1 is seated on the subject supporting means 12 without lying down, a conventional bed section is unnecessary, space can be saved, and the apparatus can be made more compact. Furthermore, since it is not necessary to keep the subject within the dome, there is no need to cause psychological anxiety to the subject.

According to this embodiment, since a plurality of slice planes can be photographed simultaneously by one scan as described above, the equivalent scanning time per slice can be reduced. Furthermore, if the speed of the subject supporting means 12 can be increased depending on the subject, the equivalent scanning time per image can be further shortened. Similarly, by miniaturizing the pitch W of the collimator 13 and using the X-ray tube 10 with a longer focal point, thinner slice planes can be imaged, and the scan time can be further shortened. Because of this, the scanning time per subject is also shortened, so that the throughput of the subject can be improved.

Furthermore, when photographing multiple slice planes, conventionally it was necessary to shift the subject by moving the top plate for each slice, but according to this embodiment, such operations can be reduced and in some cases Since this becomes unnecessary, the burden on the operator can be reduced. Furthermore, since the number of times the X-ray tube 10 is irradiated with X-rays is significantly reduced, the life of the X-ray tube 10 can be extended.

Furthermore, since the conventional high-speed rotation of the rotating imaging mechanism is no longer required and the subject is rotated slowly, the amount of X-ray irradiation per unit time can be reduced, thereby reducing the burden on the X-ray tube. It can be reduced. Furthermore, when a fixed anode X-ray tube is used as the X-ray tube 10, the anode is fixed, so the cooling method is simple, and when a grounded anode type is used as the X-ray tube 10, for example, water-cooled Sufficient cooling can be achieved by implementing simple methods such as: Alternatively, a rotating anode type may be used as the X-ray tube 10, and in this case as well, the rotation speed may be low, so a similar cooling method can be applied.

If there are unnecessary slice planes among the plurality of slice planes to be photographed at the same time, the X-ray incident plane of the collimator 12 may be shielded with a shutter 20 as shown in FIG. Furthermore, when changing the slice plane, the height position of the subject support means 12 may be raised or lowered, or the height positions of the X-ray tube 10 and the X-ray detector 11 may be raised or lowered.

FIGS. 7(a) and 7(b) are a top view and a side view showing a second embodiment of the present invention, showing the schematic structure of the main parts. The subject 1 is supported by a rotatable subject support means 12 . An X-ray tube 10 and an X-ray detector 21 are provided facing each other on both sides of the subject 1, and both the X-ray tube 10 and the X-ray detector 21 are fixed to an arm 22. Arm 2
2 is rotatably attached to the support portion 23 via a shaft 24, and rotates within a range of θ with the C-axis as the rotation center. That is, the X-ray tube 10 and the X-ray detector 22 are configured to be integrally tiltable about the C-axis as a fulcrum, and are capable of tilting within a range of so-called θ. This θ is set within a range of ±25°, for example. Further, as shown in FIG. 4, the subject support means 12 may be tilted.

Further, the arm 22 is configured to be movable up and down along the body axis Z of the subject 1, so that any slice plane of the subject 1 can be set. Alternatively, the subject support means 12 may be moved up and down as in FIG. 1.

Although not shown in FIGS. 7(a) and (b), the first
As shown in the figure, a drive section 15, a data collection section 16, a reconstruction section 1
7, a display section 18 and a system control section 19 are provided. Vertical movement and tilting movement of the subject support means 12, arm 22
The vertical movement and tilting operation can be performed by the drive section 15.

With this embodiment, for example, when performing continuous scanning while continuously moving the slice plane at high speed,
First, data for one slice is collected while the subject 1 is continuously rotated by the subject support means 12, and then the arm 22 is moved up or down by the slice length to collect data for the second slice. and repeat these operations to perform continuous scanning.

According to this embodiment, even when such continuous scanning is performed, it can be performed without a slip ring due to the omission of the rotating imaging mechanism. Moreover, it can be carried out without occupying extra space and without putting a psychological burden on the subject 1.

Furthermore, in each embodiment of the present invention, when supporting the subject on the subject support means, it is effective to use a magic band for fixing the subject. Particularly in the case of a body with a soft structure that contains a lot of fluid, such as a human body, even a slight shift in the subject can affect the reproducibility of data (although this can be prevented).

The present invention can be applied not only to X-ray CT imaging but also to indirect X-ray imaging. In this case, if the subject 1 is kept in a supported state without rotating. good. By using these methods together,
It is now possible to adopt a method in which a simple diagnosis is made based on a fluoroscopic image obtained by indirect X-ray photography, and then CT photography is taken of a necessary region, thereby improving diagnostic performance.

Each numerical value shown in this example shows an example, and can be arbitrarily changed depending on the purpose, use, etc.

[Effects of the Invention] As described above, according to the present invention, a subject is rotatably disposed between an X-ray tube and an X-ray detector, which are respectively fixed, and CT
Since imaging is performed, an expensive rotating imaging mechanism and slip ring are not required, space is saved, the apparatus can be made smaller, and concerns about the subject can be eliminated.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a first embodiment of the X-ray CT device of the present invention, FIG. 2 is a schematic diagram of a two-dimensional X-ray detector used in the device of this embodiment, and FIG. 3 is a schematic diagram of a two-dimensional X-ray detector used in this embodiment. FIG. 4 is a schematic diagram of the collimator used in the device of this example. FIG. 4 is an explanatory diagram of the function of the subject support means used in the device of this example. FIG. 6 is a schematic diagram showing a modification of this embodiment, FIGS. 7(a) and 7(b) are top and side views showing a second embodiment of the present invention, and FIGS. 8 and 9.
The figures are a schematic diagram and a layout diagram of a conventional example. 1... X-ray tube, 11... Two-dimensional X-ray detector,
12... Subject support means, 13.14... Collimator, 15... Drive unit, 20
...Shutter, 21...Detector, 22...Arm. -11111)------111111\3

Claims (7)

[Claims] (1) X obtained by irradiating X-rays from the circumferential direction of the subject
In an X-ray CT device that reconstructs an image based on ray projection data, an X-ray tube and an X-ray detector are each fixedly provided, and an X-ray tube and an X-ray detector are rotatably provided between the X-ray tube and the X-ray detector. 1. An X-ray CT apparatus comprising: a subject support means having an object supporting means; (2) The X-ray CT apparatus according to claim 1, wherein the X-ray tube and the X-ray detector are configured to be integrally movable up and down. (3) The X-ray CT apparatus according to claim 1, wherein the X-ray tube and the X-ray detector are configured to be integrally tiltable. (4) The X-ray CT apparatus according to claim 1, wherein the subject support means is configured to be tiltable. (5) The X-ray CT apparatus according to claim 1, wherein a collimator is provided between the X-ray tube and the subject support means. (6) The X-ray CT apparatus according to claim 1, wherein a second collimator is provided between the subject support means and the X-ray detector. (7) The X-ray CT according to claim 1, wherein the X-ray detector is composed of a plurality of unit detection elements arranged two-dimensionally.
Device.