JP3110778B2 - X-ray CT system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray CT apparatus having an improved X-ray high voltage generator.

[0002]

2. Description of the Related Art As an example of an apparatus requiring an X-ray high-voltage apparatus, an X-ray CT apparatus as shown in FIG. 8 is known.
The X-ray CT apparatus includes a bed 1 supporting a subject 3 and an X-ray CT apparatus.
It comprises a gantry unit 2 having a built-in X-ray imaging mechanism that rotates around the subject 3 by integrating the ray tube 4 and the detector 5.

The couch 1 is provided with a top plate 6 which directly supports the subject 3 and is movable in the horizontal direction X, and a height adjustment unit 7 which adjusts the height position of the top plate 6 in the vertical direction Z. The gantry 2 includes a dome 8 for guiding the subject 3 moved in the horizontal direction X by the top plate 6. The dome 8 guides the inside of the subject 3 guided in the dome 8 around a plane (slice plane) L to be imaged. X-ray irradiation is performed while the X-ray tube 4 and the detector 5 constituting the imaging mechanism are integrally rotated, and CT imaging is started.

[0004] The X-rays transmitted through the subject 3 are detected as X-ray projection data by being incident on the detector 5, and are reconstructed on the arbitrary slice plane L of the subject 3 by reconstructing these X-ray projection data. A tomographic image along it can be obtained.

FIG. 9 shows an X-ray tube 4 of such an X-ray CT apparatus.
FIG. 1 is a block diagram showing a conventional X-ray high-voltage device for supplying a high-voltage DC voltage to an AC power supply. An AC voltage from an AC power supply 10 is converted into a DC voltage by a smoothing unit 11, and the DC voltage is then converted by a chopper inverter 12 into an inverter. After being converted into an AC voltage by the method, the AC voltage is boosted in the high-voltage transformer 13 and further rectified to output a high-voltage DC voltage to be supplied to the X-ray tube 4.

Such an inverter type power supply is configured such that each block is integrated and mounted on a rotating mechanism of the gantry 2 of the X-ray CT apparatus shown in FIG. Here, as an example, the volume and weight of each block are 10 liters and 6 kg for the smoothing unit 11, 20 liters and 18 kg for the chopper inverter 12, and 50 liters and 50 kg for the high-pressure transformer 13 as an example. Therefore, the gantry 2 must have sufficient space and strength to accommodate the total volume of 80 liters and sufficiently support the total weight of 74 kg. Further, in order to increase the capacity of the X-ray high-voltage device, it is necessary to adopt a large-capacity circuit element used in each block, so that the capacity and weight are further increased.

[0007]

However, in a conventional X-ray high-voltage apparatus, since the volume and weight are relatively large,
In the case of mounting on a gantry or the like of a line CT apparatus, there is a problem that mounting is restricted. That is, when the volume and the weight increase, it becomes difficult to mount the X-ray high-voltage device in a well-balanced manner based on the restrictions of the space of the gantry or the layout. Even if mounting becomes possible, if the unit needs to be replaced for maintenance and inspection, the large volume and weight will increase the work load, as described above, which will put a burden on workers and pose a hazard. Exposed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to reduce mounting restrictions due to the volume and weight of an X-ray high voltage generator.

[0009]

In order to achieve the above object, the present invention provides an X-ray tube for irradiating X-rays with an output from a high-voltage generating means and a detector for detecting X-rays transmitted through a subject. In an X-ray CT apparatus that collects projection data of a subject by rotating a rotating body having attached thereto and reconstructs a tomographic image based on the projection data, each of the high-voltage generating means is provided on the rotating body. And a plurality of power supply units having predetermined output specifications, wherein a plurality of types of outputs are obtained by changing the combination of the plurality of power supply units.

[0010]

According to the present invention, a plurality of power supply units are used as high voltage generating means, and these are mounted on a rotating body together with an X-ray tube and a detector. Thus, the volume and weight of each power supply unit attached to the rotating body may be small, so that the high voltage generating means can be easily mounted on the gantry of the X-ray CT apparatus. Further, even if the unit needs to be replaced for maintenance, inspection, etc., the small unit can be handled individually, so that the replacement work becomes easy and the burden on the operator can be reduced. Further, since there are a plurality of power supply units, the power supply units can be mounted on the rotating body in a better balance than in the related art.

[0011]

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

FIG. 1 shows an embodiment of the present invention, in which the present invention is applied to an X-ray CT apparatus. 1 is the subject 3
A bed portion 2 for supporting X is composed of an X-ray tube 4 and a detector 5.
It is a gantry unit that incorporates a radiographic mechanism. The couch 1 includes a top plate 6 that directly supports the subject 3 and is movable in the horizontal direction X, and a height adjustment unit 7 that adjusts the height position of the top plate 6 in the vertical direction Z. In addition, the gantry 2 includes a dome 8 that is moved in the horizontal direction X by the top plate 6 and guides the subject 3. Guided inside the dome 8, X-ray irradiation is performed around the imaging surface (slice surface) of the subject 3 while integrally rotating the X-ray tube 4 and the detector 5 constituting the imaging mechanism. CT imaging is started. The X-ray tube 4 and the detector 5 are attached to a rotation mechanism 15.

In this embodiment, a plurality of, for example, eight inverter type high voltage power supply units (hereinafter simply referred to as high voltage power supply units) 16 are mounted on the rotating mechanism 15 of the gantry 2 as shown in FIG. When these high-voltage power supply units are sequentially indicated by 16A to 16H, they are connected as shown in FIG.

It is assumed that the output specification of one high-voltage power supply unit 16 is set to 60 KV (output voltage) and 50 mA (output current). High voltage power supply units 16A and 16
B are connected in series via switches 17A and 17B, and high-voltage power supply units 16C and 16D
A second connection circuit b, which is connected in series via switches 17C, 17D, and a third connection circuit, in which high-voltage power supply units 16E and 16F are connected in series via switches 17E and 17F.
And a fourth connection circuit d in which the high-voltage power supply units 16G and 16H are connected in series via switches 17G and 17H are connected in parallel to each other and connected to both ends of the X-ray tube 4. . By selecting the open / close mode of the switches 17A to 17H, one high-voltage power supply unit 16
The output specifications are as follows. The minimum unit is 60 KV, 50 mA, and a desired output obtained by combining the minimum output can be supplied to the X-ray tube 4. Next, the operation of the present embodiment will be described.

First, when all the switches 17A to 17H are open, no voltage is supplied to the X-ray tube 4 because no closed circuit is formed. Assuming that any one of the switches 17A to 17B is closed as a first connection mode, a closed circuit for connecting any one of the high-voltage power supply units 16 and the X-ray tube 4 is formed. Is supplied with a minimum output of 60 KV and 50 mA.

As a second connection mode, the switches 17A, 1
7B are closed, the high voltage power supply units 16A, 16A
A closed circuit for connecting the X-ray tube 4 to the first connection circuit a in which B is connected in series is formed as shown in FIG.
Is omitted), the X-ray tube 4 is set to 120 KV, 5
An output of 0 mA is provided.

Assuming that the switches 16C and 16D are closed as a third connection mode in addition to the second connection mode, a second connection circuit b in which the first connection circuit a and the high-voltage power supply units 16C and 16D are connected in series. 5 is formed as shown in FIG. 5, and an output of 120 KV and 100 mA is supplied to the X-ray tube 4.

Assuming that the switches 16E and 16F are closed in addition to the second and third connection modes as the fourth connection mode, the first connection circuit a, the second connection circuit b, and the high voltage power supply units 16E and 16F are connected. By forming a closed circuit for connecting the parallel circuit with the third connection circuit c connected in series and the X-ray tube 4 as shown in FIG.
KV, 150 mA output is provided.

Assuming that the switches 16G and 16H are closed in addition to the second to fourth connection modes as the fifth connection mode, the first connection circuit a, the second connection circuit b, and the third connection circuit c A closed circuit for connecting the X-ray tube 4 and a parallel circuit with the fourth connection circuit d in which the high-voltage power supply units 16G and 16H are connected in series is formed as shown in FIG. A maximum output of 120 KV and 200 mA is supplied.

As described above, according to the present embodiment, a plurality of high-voltage power supply units 16 having predetermined output specifications are prepared, and by combining them, the output specification of one high-voltage power supply unit is set to the minimum output, and Any combined output can be obtained. As a result, an arbitrary high-voltage DC voltage can be supplied to the X-ray tube only by preparing a plurality of high-voltage power supply units having a small capacity and weight. It can be installed without. Further, even when the unit needs to be replaced for maintenance or inspection, handling the small unit facilitates the replacement operation, and can prevent the burden on the operator and the risk of danger.

In this embodiment, a limited number of high-voltage power supply units and a limited connection mode have been described as examples.
By selecting the number and the connection mode according to the embodiment without limiting to this, an arbitrary output can be obtained and supplied to the X-ray tube.

[0022]

As described above, according to the present invention, the high-voltage generating means can be easily and well-balanced mounted on the gantry of the X-ray CT apparatus, and the unit can be replaced for maintenance and inspection. Even if necessary, small units can be handled individually, which facilitates replacement work and reduces the burden on the operator.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a schematic sectional view showing a main part of the embodiment.

FIG. 3 is a block diagram illustrating a configuration example of an X-ray high-voltage device used in the present embodiment.

FIG. 4 is a block diagram illustrating the operation of the present embodiment.

FIG. 5 is a block diagram illustrating another operation of the embodiment.

FIG. 6 is a block diagram illustrating another operation of the present embodiment.

FIG. 7 is a block diagram illustrating another operation of the present embodiment.

FIG. 8 is a schematic sectional view showing a configuration of an X-ray CT apparatus.

FIG. 9 is a block diagram showing a conventional example.

[Explanation of symbols]

2 Mount part 4 X-ray tube 5 Detector 15 Rotation mechanism 16, 16A to 16H Inverter type high voltage power supply unit 17A to 17H Switch

Claims (3)

(57) [Claims] 1. A rotating body provided with an X-ray tube for irradiating X-rays by an output from a high-voltage generating means and a detector for detecting X-rays transmitted through a subject is rotated to obtain projection data of the subject. In the X-ray CT apparatus that collects and reconstructs a tomographic image based on the projection data, the high-voltage generating means includes a plurality of power supply units each provided on the rotating body and having a predetermined output specification, An X-ray CT apparatus, wherein a plurality of outputs are obtained by changing a combination of the plurality of power supply units. 2. The X-ray CT apparatus according to claim 1, wherein said high voltage generating means obtains the plurality of types of outputs by changing a connection mode of the plurality of power supply units. 3. The power supply unit according to claim 1, wherein the plurality of power supply units are provided on the rotating body by the same number with the X-ray tube interposed therebetween, when viewed from a direction in which the subject is guided to the dome. 2. The X-ray CT apparatus according to 2.