JP2003079608A - X-ray ct system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray CT system wherein the scanning speed is increased without increasing a centrifugal force due to the rotation of a scanner rotating board, and which can cope with an examination of an organ accompanying a quick movement such as the heart as well, in the X-ray CT system of a multiple tubular bulb style. SOLUTION: Three or more X-ray tubes which emit X-rays to a subject, and three or more X-ray detecting units which detect the X-ray tubes and the transmitted X-ray amount distribution of the X-rays having been emitted from the X-ray tubes and transmitted through the subject are confronted with each other, and loaded on a scanner rotating section. Then, an inverter type X-ray high voltage device which is constituted of a converter, an inverter and a high voltage generating circuit is divided into at least three units. In this case, the converter converts a commercial power source into DC. The inverter converts the DC voltage from the converter into AC. The high voltage generating circuit raises the voltage of the AC voltage from the inverter and rectifies it. Then, respective divided units are arranged between the plurality of X-ray tubes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray CT apparatus, and more particularly to an examination of an organ such as a heart that is moving rapidly by increasing the scanning speed without increasing the centrifugal force due to the rotation of the scanner turntable. Multi-tube X-ray C that can be used
Regarding the T device.

[0002]

2. Description of the Related Art A computer tomography apparatus (X-ray CT apparatus) for photographing an internal tomographic plane of an object using X-rays.
Is already widely used in the medical field, and further, the spiral scan type X-ray CT apparatus moves the bed on which the subject is mounted during X-ray irradiation to move the subject in a spiral shape. It enables to scan a wide area by scanning to, and by doing so, the inspection time is greatly shortened and the inspection ability is remarkably improved as compared with the conventional method. Such a conventional X-ray CT apparatus is generally provided with a single X-ray generation source, and sequentially scans the subject while rotating it around 360 degrees. In particular, in a spiral scan X-ray CT apparatus that scans and measures a subject in a wide range while spirally scanning it, it has been strongly desired to shorten the examination time. As a scanning method of this spiral scan type X-ray CT apparatus, an X-ray source and an X-ray detector are mounted on a scanner turntable, and the scanner turntable is continuously rotated to perform scanning (hereinafter referred to as a mechanical system). I will call it the scan method) is the current mainstream. However, in this method, since it is necessary to rotate the X-ray tube at a high speed and continuously supply power to the X-ray tube, the mechanical strength of the scanner, the reliability of the power supply means, etc. From the point of securing, it is not possible to expect a drastic speedup than 0.5 seconds / 360 degrees at this point.

On the other hand, in the electronic scan type device,
Although there is an apparatus capable of achieving an ultra-high scan speed of about 50 msec, however, this electronic scan type apparatus has problems such as its maintainability and the apparatus itself being expensive. Therefore, the mechanical scan type spiral scan type X
As a device capable of measuring a wide range of images in a line CT apparatus in a short time, there is, for example, one disclosed in Japanese Patent Laid-Open No. 8-280663. This is a so-called multi-tube type X-ray CT apparatus in which a plurality of X-ray sources and X-ray detectors facing each other are provided in the circumferential direction.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the case of the same scan time, for example, when the scanning speed of the scanner is three pairs of the X-ray source and the X-ray detector, the centrifugal force of the scanner turntable generates one X-ray in the conventional case. 1/3 of the case where the source is provided is sufficient, and it becomes easy to secure the mechanical strength of the scanner turntable and the reliability of the power supply means, and the inspection time can be shortened. In particular,
In recent years, with the remarkable development of medical technology, it has been required to further shorten the examination time more than ever before, and it is necessary to perform three-dimensional analysis of organs with fast movements such as the heart and dynamic analysis of blood flow. This is all the more so when doing so. Thus, reducing scan time is a potential need,
The multi-tube method is one method that meets this need, but even in this method, the object to be mounted on the scanner should be as light as possible and the method of mounting the object to stably rotate the scanner turntable should be used. Must also be considered. In addition to the X-ray tube and the X-ray detector, there is an X-ray high-voltage device that supplies electric power to the X-ray tube as an object to be mounted on the scanner. In this X-ray high voltage device, a high voltage transformer can be made smaller and lighter, and the voltage applied to the X-ray tube (hereinafter,
An inverter type X-ray high voltage device capable of reducing the pulsation of the tube voltage) is advantageous.

In this inverter type X-ray high voltage device, a commercial AC power source is converted into a DC voltage by a converter, and this DC voltage is converted into an AC voltage having a frequency higher than the commercial power source frequency by the inverter, and this high frequency So that the AC high voltage is boosted by a high voltage transformer, the boosted AC high voltage is rectified by a high voltage rectifier into a DC high voltage, and this DC high voltage is applied to an X-ray tube to generate X-rays. In order to downsize the high voltage transformer and reduce the pulsation of the tube voltage waveform,
The operating frequency of the inverter is higher than 20kHz.

Therefore, as in the case where the inverter type X-ray high-voltage device is provided on the multi-tube type scanner rotary disk with one conventional X-ray generating source, a controller unit including a converter and an inverter and a high-voltage unit are installed. In the method of dividing into two units of the high voltage generator unit after the voltage transformer and mounting them on the scanner turntable, it is necessary to take measures such as mounting a heavy object such as a counter balance weight to balance the weight. Becomes However, in the method of mounting the counter balance weight described above, the weight of the entire object mounted on the scanner turntable increases, which increases the centrifugal force of the scanner turntable. Therefore, the mechanical strength of the scanner turntable and the X-ray tube are increased. It becomes difficult to secure the mechanical strength of the object mounted on the scanner turntable such as an X-ray detector and an X-ray high voltage device. As described above, in the conventional multi-tube type X-ray CT apparatus described above, no consideration has been given to the method of mounting the mounted object on the scanner turntable.

Therefore, an object of the present invention is to use a multi-tube type X
In the X-ray CT apparatus, the scanning speed is increased without increasing the centrifugal force due to the rotation of the scanner turntable, and the X-ray C that can also be used for the examination of organs such as the heart that moves rapidly.
It is to provide a T device.

[0008]

The above object can be achieved by the following means. (1) An X-ray high-voltage device including a converter that converts a commercial power supply into a direct current, an inverter that converts a direct-current voltage from the converter into an alternating current, and a high-voltage generation circuit that boosts and rectifies the alternating-current voltage from the inverter. , At least three or more X-ray tubes which are supplied with a DC voltage from the high-voltage generating circuit and emit X-rays, and which are arranged so as to face these X-ray tubes and which are emitted from the X-ray tubes and pass through a subject. The transmitted X-ray dose distribution of the generated X-rays and amplify the detection signal 3
A scanner rotation unit that rotates one or more X-ray detection units so as to rotate around the subject, and an output signal from the X-ray detection unit of the scanner rotation unit is processed to reconstruct a tomographic image of a diagnostic region. An image processing apparatus, an image display apparatus for displaying a tomographic image by inputting an output signal from the image processing apparatus, and a power feeding section for supplying power to an X-ray high voltage apparatus mounted on a scanner rotating section. In the provided X-ray CT apparatus,
The X-ray high voltage apparatus is divided into at least three or more units, and each of the divided units is mounted on the scanner rotating unit between the plurality of X-ray tubes.

(2) A laminated structure of a copper plate and an insulator is used for all or part of the electrical connection between the above units.

(3) X mounted on the scanner rotating unit
The power feeding means for feeding power to the line high voltage device is a non-contact power feeding means by electromagnetic induction.

(4) Each unit to be divided is a converter, an inverter, and a high voltage generating circuit.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 and FIG. 2 are views showing a configuration in the case of using three X-ray tubes as a first embodiment of a multi-tube type X-ray CT apparatus according to the present invention. The structure is as follows. That is, this X-ray CT apparatus radiates X-rays to the diagnostic region of the subject 110 placed on the table 120, detects the transmitted X-ray dose distribution, reconstructs a tomographic image, and displays it as an image. As shown in FIG. 2, the power supply / signal transmission unit 10, the converter unit 20, the inverter unit 30, the high voltage generation circuit unit 40, the high voltage cables 51a to 51c and 52a to 52c, and the three X-rays. Tube 60a-6
0c, X-ray detection units 70a to 70c, an image processing device 80, an image display device 90, a scanner rotation unit 100, and the like.

FIG. 1 shows a scanner rotating unit 1 which is an essential part of the present invention.
00 shows the mounting status of each unit. This scanner rotating part 10
At 0, three X-ray tubes 60a-60c are mounted at equal intervals, and three X-ray detectors 70a-70c are arranged so as to face each other.
Are arranged. Normally, the coolers 61a to 61c are arranged beside the X-ray tubes 60a to 60c, respectively. A converter unit is installed between the X-ray tubes 60a-60c.
20 and inverter unit 30 and high voltage generation circuit unit 40
Are placed.

Below, a more detailed structure of each part and its role and operation will be explained. In FIG. 2, the power supply and signal transmission unit 10 is a unit that supplies electric power to each circuit mounted on the rotating unit and sends the detection signals processed by the X-ray detection units 70a to 70c to the image processing apparatus 80. As a means for this, the brush 12 (12a, 12b for power supply, 12c ~
12e is for signal transmission) and a slip ring 11 (11a and 11b are for power feeding, 11c to 11e are for signal transmission).
The converter 21 converts the AC voltage of the commercial AC power supply 1 into a desired DC voltage, and the converter unit 20 includes a converter 21 and a capacitor 22 that smoothes the output voltage. The inverter unit 30 receives the DC output from the converter unit 20, and the smoothing capacitor 31 and the inverter 32 for suppressing the surge voltage applied to the switch of the inverter 32 by the inductance of the wiring between the converter unit 20 and the inverter unit 30. And a resonance capacitor 33. The inverter 32 is
The DC voltage output from the converter unit 30 is converted into a high frequency AC voltage, and the X-ray tubes 60a to 60c
The voltage applied to the tube, that is, the tube voltage is controlled. The resonance capacitor 33 makes it easy to supply a large amount of power to the load by utilizing the resonance phenomenon together with the leakage inductance of the high-voltage transformer 41, and may be inserted as necessary.

The inside of the high voltage generating circuit 40 is filled with insulating oil for the purpose of ensuring insulation withstanding voltage and cooling, and the inside thereof is filled with a high voltage transformer 41, a high voltage rectifier 42, and a smoothing capacitor.
43, filament heating transformers 44a to 44c, etc. are mounted.
The high voltage transformer 41 inputs the AC output voltage from the inverter 32 and boosts the voltage to a desired voltage for generating X-rays from the X-ray tubes 60a-60c. The high voltage rectifier 42 converts the AC high voltage of the high voltage transformer 41 into a DC high voltage, and the smoothing capacitor 43 has a function of smoothing its output. High voltage cables 51a-51c and 52a-5
2c is an X-ray tube 60a to 6 which outputs the output DC high voltage of the high voltage generation circuit 40.
It is to make an electrical connection for applying to 0c. The filament heating transformers 44a to 44c are transformers for supplying electric power to the filaments of the X-ray tubes 60a to 60c, and the output electric power is adjusted by an inverter (not shown) provided in the preceding stage of the X-ray tube. It has a role of controlling the current of 60a to 60c, that is, the tube current so as to match the target value.
The X-ray tubes 60a to 60c are supplied with the DC high voltage output from the high voltage generating circuit 40 and radiate X-rays toward the subject 110. Then, the X transmitted through the subject
The lines are collimated and correspond to each X-ray detection unit 70a.
It is incident on ~ 70c. The X-ray detectors 70a to 70c detect the dose distribution of the transmitted X-rays emitted from the X-ray tubes 60a to 60c and transmitted through the subject, and amplify the detection signal. The detectors 71a to 71c for detecting the dose distribution and the preamplifiers 72a to 72c for amplifying the detection signals from the detectors 71a to 71c, respectively. The image processing apparatus 80 also inputs and processes the output signals from the X-ray detection units 70a to 70c via the power feeding and signal transmission unit 10, and reconstructs a tomographic image of the diagnostic region of the subject 110. It is a thing. Further, the image display device 90 is the image processing device.
It displays the tomographic image by inputting the output signal from 80,
For example, a television monitor. Since the present apparatus adopts the three-tube method, a large amount of image information can be obtained in a short time, so that an X-ray CT apparatus with high diagnostic ability can be realized.

Although not shown in detail in the present invention in FIG. 1, when actually controlling the X-ray, an anode drive circuit for controlling the rotation speed of the anode of the X-ray tube is also required.

Next, the mounting arrangement of the scanner rotating unit 100 of the X-ray CT apparatus according to the present invention in such a configuration will be described with reference to FIG. The scanner rotating unit 100 has a rotating frame 140 in which an opening 130 for inserting a subject is formed in the center, and on one side surface of the rotating frame 140, X-ray tubes 60a to 60c are mounted at equal intervals. , X-ray tubes 60a-60c face each other, and X-ray detectors 70a-70c are mounted so as to face them. Then, the X-ray high voltage apparatus is provided with the converter unit 20.
The inverter unit 30 and the high-voltage generating circuit unit 40 are divided into three parts, and are respectively mounted and arranged between the X-ray tubes 60a to 60c so that their weights are substantially equal. For electrical connection between the converter unit 20 and the inverter unit 30, it is possible to use ordinary electric wires, but since the distance between them is relatively large, the inductance of the electric wires tends to be large, which causes the inverter switch to switch. There is a high possibility that the surge voltage generated due to the temporal change of the current flowing through the inductance in this case becomes a problem. That is, if this surge voltage exceeds the rating of the switch, there is concern that the switch may be damaged. Therefore, in order to reduce the inductance in the wiring between the converter unit 20 and the inverter unit 30, it is also effective to use a laminated structure of a copper plate and an insulator as shown in FIG. On the other hand, even in the connection from the inverter unit 30 to the high voltage generation circuit unit 40, it is also effective to use a copper plate in the same manner as in FIG. 4 instead of the normal electric wire in order to reduce the inductance in response to the high frequency operation of the inverter. It becomes a means.

With the above-described mounting, the counter balance weight conventionally used to maintain the weight balance of the entire scanner can be suppressed to the necessary minimum, and the mechanical vibration and the shake during the scanning can be minimized. can do. And this leads to that a better diagnostic image can be provided.

Next, FIG. 3 shows a second embodiment of the present invention. The power feeding and signal transmission section in this embodiment is shown in FIG.
Unlike the first embodiment, the power supply of 10 is different from the first embodiment.
The electromagnetic induction power transmission means 2 disclosed in Japanese Patent No. 41926, Japanese Patent Laid-Open No. 8-336521, etc. is applied. By doing so, the problems of wear and corrosion caused by mechanical sliding contact between the brush and the slip ring are completely eliminated, and further improvement in reliability can be expected.

In the above embodiment, the X-ray high voltage device is divided into three units, and each unit is arranged between the three X-ray tubes. However, the present invention is not limited to this, and the X-ray high voltage device is not limited to this. The line high voltage device is divided into three or more units to optimize weight balance (minimum counter balance weight).
So that they can be placed between each X-ray tube. Alternatively, the converter unit 20 and the inverter unit 30 may be combined into one, and the high voltage generation circuit may be divided into two to form three units as a whole, which may be arranged between the X-ray tubes. . Furthermore, in the first and second embodiments, the converter and the subsequent parts are mounted on the scanner rotating part, but the invention is not limited to this. For example, the inverter and the subsequent parts of the X-ray high voltage device are mounted on the scanner, and the mounted part. The object of the present invention can be achieved by dividing the portion into three or more units and disposing them between the X-ray tubes. Further, in the above-mentioned embodiment, an example using three X-ray tubes as the X-ray source has been described, but the present invention is not limited to this, and three X-ray tubes can be used as long as the object of the present invention can be achieved. A multi-tube system having the above X-ray source may be used.

As described above, the gist of the present invention is to divide the weight of all or part of the X-ray high-voltage device mounted on the scanner into three or more equal parts in three or more multi-tube X-ray CT devices. By dividing the above and arranging them between each tube to ensure the weight balance of the entire scanner, extra load such as counter balance weight is minimized and reliability suitable for higher speed scanning The point is that a high-quality X-ray CT apparatus can be provided.

[0022]

As described above, according to the present invention, the counterbalance weight for ensuring the weight balance of the objects mounted on the scanner is minimized to reduce the burden on the scanner and at the same time during scanning. Mechanical vibration, shake, etc. can also be minimized. This leads to the provision of a better diagnostic image, and the three or more multi-tube type X-ray CT apparatus according to the present invention is compared with the conventional one-tube type X-ray CT apparatus. As a result, the following effects can be obtained.

(1) When there are three X-ray tubes, equivalent diagnostic ability can be obtained at a scanning speed of one third. Therefore, high-speed scanning is possible, and the invention can be applied to diagnosis of organs such as the heart that move rapidly.

(2) Since the centrifugal force generated by the rotation is proportional to the square of the scanning speed, it is necessary to secure the mechanical strength of each unit and the X-ray tube which constitute the X-ray high voltage device as compared with the one-tube system. It will be much easier.

(3) When power is supplied by mechanical sliding contact between the slip ring and the brush, the problems of wear and corrosion can be reduced and reliability can be improved.

(4) The X-ray dose required for the X-ray tube increases with the increase in the speed of scanning, and the burden increases. However, in this method, three or more X-ray tubes are shared, so that one X-ray tube is used. Can reduce the burden of.

[Brief description of drawings]

FIG. 1 is a mounting layout view of each unit of a scanner rotating unit according to the present invention.

FIG. 2 is a diagram showing a configuration of a first embodiment of a three-tube type X-ray CT apparatus according to the present invention.

FIG. 3 is a diagram showing the configuration of a second embodiment of a three-tube X-ray CT apparatus according to the present invention.

FIG. 4 is a diagram showing a method for electrically connecting a converter and an inverter in the embodiment of the present invention.

[Explanation of symbols]

1 ... Commercial power supply, 2 ... Electromagnetic induction power transmission means, 10 ... Electric power feeding and signal transmission section, 11 ... Slip ring, 12 ... Brush, 20 ... Converter unit, 30 ... Inverter unit, 40 ... High voltage generation circuit, 41 ... High Voltage transformer, 42 ... High voltage rectifier, 44
… Filament heating transformer, 51, 52… High voltage cable,
60 ... X-ray tube, 61 ... X-ray tube cooler, 70 ... X-ray detector, 71 ...
X-ray detector, 72 ... Preamplifier, 80 ... Image processing device, 90 ...
Image display device, 100 ... Scanner rotating unit, 110 ... Subject, 12
0 ... table, 130 ... scanner opening, 140 ... scanner rotating frame

Claims (4)

[Claims] 1. An X-ray high voltage including a converter for converting a commercial power source into a direct current, an inverter for converting a direct current voltage from the converter into an alternating current, and a high voltage generating circuit for boosting and rectifying the alternating voltage from the inverter. A device, at least three or more X-ray tubes that are supplied with the DC voltage from the high-voltage generating circuit and emit X-rays, and are arranged so as to face these X-ray tubes and are emitted from the X-ray tubes. A scanner rotating unit that rotates around a subject by facing three or more X-ray detecting units that detect the transmitted X-ray dose distribution of X-rays that have passed through the sample and that amplifies the detection signal, and the scanner rotating unit. Image processing apparatus for processing output signals from three or more X-ray detection units to reconstruct a tomographic image of a diagnostic region, and image display for inputting output signals from the image processing apparatus to display a tomographic image The device and the scan X comprising a power supply unit for supplying power to the X-ray high voltage device mounted on the rotating unit
In an X-ray CT apparatus, the X-ray high voltage apparatus is divided into at least three or more units, and each of the divided units is mounted on a scanner rotating unit between the plurality of X-ray tubes. 2. The X-ray CT apparatus according to claim 1, wherein a laminated structure of a copper plate and an insulator is used for electrical connection of all or some of the units. 3. The X-ray according to claim 1, wherein the power feeding means for feeding power to the X-ray high-voltage device mounted on the scanner rotating unit is a non-contact power feeding means by electromagnetic induction. CT device. 4. The X-ray CT apparatus according to claim 1, wherein each unit to be divided is a converter, an inverter, and a high voltage generating circuit.