JP2867909B2 - X-ray CT system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray transmitting data between an X-ray collecting means and a data transfer unit via a ring-shaped electrode formed in a ring shape and a brush electrode in contact with the ring-shaped electrode. It relates to a CT apparatus.

[0002]

2. Description of the Related Art As a conventional X-ray CT apparatus of this type, for example, there is an apparatus disclosed in Japanese Patent Publication No. 4-27857. The main part of this X-ray CT apparatus is shown in FIG. 6 and will be described below.

[0003] An X-ray tube (not shown) and an X-ray collecting unit 20 supported opposite to the X-ray tube are provided on the ring-shaped electrode 10 formed in a ring shape. The X-ray collecting unit 20 rotates together with the ring-shaped electrode 10 and receives X-rays from an X-ray tube (not shown).
A line is detected, and signal data is collected from the detected X-ray. Collected signal data is output from the X-ray collecting unit 20, and these signal data pass through _two signal supply points Ps ₁ and Ps ₂ to the ring-shaped electrode 10,
Is transmitted to the data transfer unit 40 via the brush electrode 30 whose position is fixed. The data transfer unit 40 transmits signal data to an external computer (not shown).

[0004] At two signal supply points Ps ₁ and Ps ₂ provided on the ring-shaped electrode 10, the signal data output from the X-ray collector 20 is divided by _two at a branch point (supply signal branch point) SP.
Are supplied in a branching direction, and from the supply signal branch point SP, each signal supply point Ps ₁ , Ps ₂
The line lengths are set so that their physical lengths are equal to each other, or the electrical lengths are equal to each other by inserting a delay unit. With this configuration, the signal data output from the X-ray collection unit 20 is
The signal data S _CW propagating clockwise in the ring-shaped electrode 10 and the counterclockwise (count
er clockwise) and is transmitted to the data transfer unit 40 after being branched into signal data S _CCW propagating in the data transfer unit 40. Therefore, the displacement of the line length difference between the signal data S _CW and S _{CCW due} to the rotation of the ring-shaped electrode 10 can be reduced to almost half as compared with the case where only one signal supply point is provided. At the same time, the signal data S _CW , S _CCW can be transmitted to the data transfer section 40 while the phases thereof are almost matched. As a result, the cutoff frequency, which is the main cause of limiting the transmission speed of signal data, can be increased (about twice in this example), and signal data can be transmitted at high speed.

[0005]

At the supply signal branch point SP described above, it is necessary to branch signal data in two directions. Therefore, if a general (for example, a BNC type T-branch connector) branch connector is used as the supply signal branch point SP, part of the signal data input to the branch connector may be reflected (see FIG. 6). When a part of the signal data enters from the output terminal of the branch connector through various paths (as indicated by dotted lines), it interferes with the input signal (data) to the [branch connector], thereby lowering the cutoff frequency. There is a problem.

The present invention has been made in view of such circumstances, and has as its object to provide an X-ray CT apparatus capable of transmitting signals at high speed by increasing the cutoff frequency. .

[0007]

The present invention has the following configuration to achieve the above object. That is, the X-ray CT apparatus according to the present invention is an X-ray CT apparatus that performs data transmission between the X-ray collection unit and the data transfer unit via a ring-shaped electrode formed in a ring shape and a brush electrode that contacts the ring-shaped electrode. In the X-ray CT apparatus, signal supply points (or brush electrodes) from the X-ray collecting means are provided at a plurality of locations on the ring-shaped electrode, and the signal supply points (or brush electrodes) are connected from the X-ray collecting means to the respective signal supply points. A supply signal branch point for branching and supplying a signal has a function of distributing an input signal to a plurality of output signals, and a characteristic of preventing the distributed output signal from interfering with the input signal (reverse characteristic). A signal distributor having a coupling attenuation characteristic; and / or providing the brush electrode at a plurality of locations (or providing a signal output point to the data transfer unit at a plurality of locations on the ring-shaped electrode). Both), a supply signal combining point for combining and supplying a signal from each of the brush electrodes (or each of the signal output points) to the data transfer unit, and having a function of combining a plurality of input signals, and A signal combiner having a characteristic (reverse coupling attenuation characteristic) of preventing interference between the output signal and the input signal.

[0008]

The operation of the present invention is as follows. A signal supply point (or a brush electrode) from the X-ray collecting means is provided at a plurality of locations of the ring-shaped electrode, and a supply signal that branches and supplies a signal from the X-ray collecting means to each signal supply point (or each brush electrode). The splitter has a function of splitting an input signal into a plurality of output signals and a characteristic (reverse coupling attenuation characteristic) of preventing interference between the distributed output signal and the input signal. Is provided.

In this signal distributor, an input signal input to an input terminal is branched to a plurality of output terminals, for example, an output terminal 1 and an output terminal 2, and output as output signals 1 and 2. . The characteristic of this signal distributor, that is, the reverse coupling attenuation characteristic, means that the output signal 1 and the output signal 2 pass through various paths and are connected to the output terminals 1 and 2.
This is a characteristic indicating that the entry can be prevented. By providing a signal splitter having a reverse coupling attenuation characteristic at a supply signal branch point, an input and branched signal is prevented from entering the output terminal 1 or the output terminal 2 through various paths. Therefore, interference with the input signal can be suppressed, and the cutoff frequency can be increased.

Alternatively, brush electrodes are provided at a plurality of locations (or signal output points to the data transfer section are provided at a plurality of locations on the ring-shaped electrode), and signals are transmitted from each brush electrode (or each signal output point) to the data transfer section. The supply signal synthesis point to be synthesized and supplied has a function of synthesizing a plurality of input signals, and has a characteristic of preventing interference between the synthesized output signal and the input signal (reverse coupling attenuation characteristic). And a signal synthesizer having the same.

The signal synthesizer combines, for example, the input signal 1 and the input signal 2 input to the input terminal 1 and the input terminal 2 and outputs the result as an output signal. By using a signal combiner (which has a reversible relationship with the above-mentioned signal distributor) having a reverse coupling attenuation characteristic, a part of the signal reflected by the output terminal portion or the data transfer portion can be removed. Output to the input terminal 1 and the input terminal 2 can be prevented. Therefore, the interference with the input signal can be suppressed, and the cutoff frequency can be increased.

Further, by providing a signal distributor at the supply signal branch point and a signal combiner at the supply signal combining point, signal interference can be suppressed. Can be enhanced.

[0013]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram illustrating a main part of the X-ray CT apparatus according to the embodiment.

In the figure, reference numeral 1 denotes a gantry, which has a ring-shaped rotating body 2. The rotating body 2 includes an X-ray tube 3 for emitting X-rays, and a plurality of X-rays for detecting transmitted X-rays emitted from the X-ray tube 3 and transmitted through a subject (not shown).
X-ray detecting unit 4) and a data collecting unit 5 for collecting signal data from transmitted X-rays detected by the X-ray detecting unit 4. Further, a ring-shaped electrode 10 is provided on the outer peripheral surface of the rotating body 2. Note that the X-ray detection unit 4 and the data collection unit 5 correspond to X-ray collection means in the present invention.

Data collection unit 5 rotating with rotating body 2
Is transmitted to the ring-shaped electrode 10 and transmitted to the data transfer unit 40 via the two brush electrodes 30a and 30b that are in contact with the outer peripheral surface of the ring-shaped electrode 10.

Referring to FIG. This figure is a simplified schematic view of the X-ray CT apparatus shown in FIG. In addition,
In this figure, for convenience of explanation, the rotating body 2, the X-ray tube 3, and the X-ray detector 4 are omitted.

The ring-shaped electrode 10 has two signal supply points Ps ₁ and Ps ₁ for supplying signal data from the data collection unit 5.
s ₂ is provided. These signal supply points Ps ₁ , Ps
The signal distributor T is located at a supply signal branch point SP which is a branch point for supplying a signal from the data collection unit 5 to s _2.
1 is provided. Therefore, the signal data transmitted from the data collection unit 5 is transmitted to the signal supply points Ps ₁ and Ps ₂ via the signal distributor T ₁ . The ring-shaped electrode 10 is provided with a terminating resistor _RT which rotates together with the data collecting unit 5 and has a constant positional relationship therewith. In addition, each signal supply point Ps ₁ , P
The path length between s ₂ and the supply signal branch point SP is adjusted so that the signal length does not shift, and the path length is adjusted to be the same length or the electrical length is matched via a delay unit (not shown). I have.

The two brushes electrodes 30a in contact with the outer peripheral surface of the ring-shaped electrodes 10, 30b is connected to the data transfer unit 40 through a signal combiner T ₂ which is disposed at a position of the supply signal combining point CP I have. Therefore, the brush electrode 30
a, signal data from 30b is made via the signal combiner T ₂ to be transmitted to the data transfer unit 40. Note that each of the brush electrodes 30a and 30b and the supply signal synthesis point CP
Are adjusted so that there is no phase shift of the signal, or the same length or the same electrical length via a delay unit (not shown).

Next, the signal distributor T described above with reference to FIG.
About ₁ and a signal combiner T ₂ will be described. This figure is
It is a circuit diagram showing an example of a signal splitter T ₁ and the signal combiner T ₂ (the hybrid 2 signal distributor).

The signal distributor T ₁ distributes an input signal input to an input terminal to obtain two output signals, and is also called a splitter. The signal combiner T2 combines _two input signals to obtain one output signal, and is also called a combiner. These signal distributor T ₁ and signal combiner T
Numeral ₂ is reversible and fulfills both functions by exchanging input and output in the circuit diagram shown in FIG.

The input terminal J ₁ of the signal distributor T ₁ includes a high-frequency transformer TR ₁ (for impedance conversion) in which a thin wire is wound around a ferrite core (not shown), and a compensation capacitor C ₁ for improving high-frequency characteristics. , [Converts unbalanced input to balanced output] high-frequency transformer TR ₂ and resistor R ₁
And to the two output terminals J ₂ and J ₃ . In the signal distributor T ₁ configured as described above (which is a hybrid two-signal distributor), the distribution loss representing the attenuation of the output signal after branching with respect to the input signal is about 3 dB,
[Prevents input of signals from output terminals J ₂ and J ₃ ] The amount of reverse coupling attenuation representing the reverse coupling attenuation characteristic becomes 20 dB or more. Further, the signal phase difference after the distribution is almost 0 °.

It is preferable that the distribution loss is small and that the reverse coupling attenuation is large.

Accordingly, the signal data input to the input terminal J ₁ is distributed and output to each of the output terminals J ₂ and J ₃ as signal data having a signal level of approximately 〔of the input signal level. [By various paths which are problematic in the conventional example shown in FIG. 6] The signal data entering from the output terminals J ₂ and J ₃ are blocked, and the interference of the signal data can be suppressed, so that the cutoff frequency can be increased. Furthermore, the signal data transmitted from the brushes electrodes 30a, 30b is, via a signal combiner T ₂ is transmitted to the data transfer unit 40. The signal data input to the input terminals J ₂ and J ₃ of the signal combiner T ₂ are combined and output to the output terminal J ₁
Although is output to the output terminal J ₁ part and data transfer unit 40
The signals reflected at the terminals are prevented from being output from the input terminals J ₂ and J ₃ , and interference with signal data can be suppressed, so that the cutoff frequency can be increased. As a result, data transmission from the data collection unit 5 to the data transfer unit 40 can be performed at high speed.

Next, a modified example will be described with reference to FIGS. FIG. 4 shows two ring-shaped electrodes 10 provided with two signal supply points Ps ₁ and Ps ₂ , and one brush electrode 3.
5 shows a modified example in which signal data is transmitted to the data transfer unit 40 via the “0”. Supply signal branch point SP
The, the signal distributor T ₁ is provided. With such a configuration, signal interference at the supply signal branch point SP can be suppressed, so that the cutoff frequency can be increased.

FIG. 5 is a signal supplied to the ring electrode 10 is carried out at only one point of the signal supply point Ps _1, the signal data are combined by the signal combiner T ₂ data transfer from the two brush electrodes 30a, 30b 5 shows a modification configured to be transmitted to the unit 40. Even with such a configuration, the signal interference at the supply signal combining point CP can be suppressed, so that the cutoff frequency can be similarly increased.

According to such modifications, the cutoff frequency can be increased.
The transmission of the signal data from the data transfer unit 40 to the data transfer unit 40 can be performed at high speed.

In the above-described embodiment and the modified example, the example in which the signal supply point and the brush electrode are provided at two positions has been described. However, the present invention is not limited to this. (Or more).

In this embodiment, the ring-shaped electrode 10
Although the X-ray CT apparatus in which is rotated has been described as an example, the present invention can also be implemented in an X-ray CT apparatus in which the position of the ring-shaped electrode 10 is fixed and the data acquisition unit 5 rotates. In this case, a brush electrode may be provided at each of the signal supply points Ps ₁ and Ps ₂ of the ring-shaped electrode 10 and / or the brush electrodes 30a and 30b may be signal output points.

[0029]

As is apparent from the above description, according to the present invention, by providing a signal distributor having an anti-coupling attenuation characteristic at a supply signal branch point, interference of a signal input from a data collection unit can be reduced. Since the frequency can be suppressed and the cutoff frequency can be increased, signal transmission can be performed at high speed.

Further, by providing a signal combiner having a reverse coupling attenuation characteristic at a supply signal combining point, interference of a signal input from the brush electrode can be suppressed and a cutoff frequency can be increased. Similarly, signal transmission can be performed at high speed.

Further, by providing a signal distributor at a supply signal branch point and a signal combiner at a supply signal combining point,
Since signal interference at branch points and synthesis points can be suppressed, signal transmission can be performed at high speed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a main part of an X-ray CT apparatus according to an embodiment.

FIG. 2 is a schematic diagram of the X-ray CT apparatus shown in FIG.

FIG. 3 is a circuit diagram showing a signal distributor and a signal combiner.

FIG. 4 is a schematic diagram showing a modification.

FIG. 5 is a schematic view showing a modification.

FIG. 6 is a diagram showing a main part of an X-ray CT apparatus according to a conventional example.

[Explanation of symbols]

1 ... gantry 2 ... rotating body 3 ... X-ray tube 4 ... X-ray detector 5 ... data collecting unit 10 ... ring electrodes 30a, 30b ... brush electrode 40 ... data transfer section T ₁ ... signal distributor T ₂ ... signal combining SP: supply signal branch point CP: supply signal synthesis point

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int.Cl. ⁶ , DB name) A61B 6/03

Claims (1)

(57) [Claims] A ring-shaped electrode formed in a ring shape;
In an X-ray CT apparatus for performing data transmission between an X-ray collecting means and a data transfer unit via a brush electrode contacting the same, signal supply points from the X-ray collecting means are provided at a plurality of positions on the ring-shaped electrode. (Or brush electrodes), and an input signal is distributed to a plurality of output signals at a supply signal branch point for branching and supplying a signal from the X-ray collecting means to each signal supply point (or each brush electrode). And / or a signal distributor having a characteristic of preventing interference between a distributed output signal and an input signal (reverse coupling attenuation characteristic), and / or providing the brush electrode at a plurality of locations. (Or signal output points to the data transfer section at a plurality of locations on the ring-shaped electrode) and from each of the brush electrodes (or each of the signal output points) to the data transfer section. The supply signal combining point for combining and supplying signals has a function of combining a plurality of input signals, and also prevents interference between the combined output signal and input signal (reverse coupling attenuation characteristic). An X-ray CT apparatus comprising a signal synthesizer having the following formula: