JP2726493B2 - Fluoroscope - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a fluoroscope that detects radiation transmitted through a subject and passes through the subject.

2. Description of the Related Art Conventionally, various fluoroscopic devices have been provided for inspecting the internal configuration of a long object such as a steel plate to be inspected. These conventional fluoroscopes irradiate the subject with radiation, for example, X-rays in time, and convert the amount of X-ray transmitted through the subject into an electric signal amount by an X-ray detector.
This electric signal amount is integrated over time to measure the intensity of X-rays.

Conventionally, two methods have been used to temporally integrate the electric signal amount output from the X-ray detector.

That is, the first system has a constant-period pulse generating circuit for generating a constant-period pulse of, for example, a square wave, as shown in FIG. 5, and the electric signal is generated at regular intervals set by the pulse. In addition to integrating the quantity, the data obtained by this integration, that is, the X-ray intensity
After performing processing such as D conversion, the data is transferred to a computer or the like in synchronization with the rise of the pulse.

In the second method, as shown in FIG. 6, the subject is conveyed at every fixed position, the position pulses generated in synchronization with this conveyance are counted, and every time an arbitrary number of position pulses are counted, ,
For example, every time a position pulse is detected, the electric signal amount is integrated during the detected position pulse, and the data obtained by the integration, that is, the X-ray intensity is subjected to A / D conversion or the like. Data is transferred to a computer or the like in synchronization with the rise of the pulse.

(Problems to be Solved by the Invention) However, each of the above-described two methods has the following advantages and also has disadvantages.

First, advantages in the case of the constant integration time method in which the integration time is set to be a fixed time by a pulse having a fixed period are arranged as follows.

(1) Even if the generation time of the position pulse changes due to the change in the transport speed of the subject, the data obtained by integrating the electric signal amount is not affected by the time change of the position pulse generation.

(2) The offset and gain of an X-ray detector and a processing circuit that performs various processes on analog data output from the X-ray detector usually fluctuate due to ambient temperature, aging, and integration time. According to the constant integration time method, there is little influence from fluctuation of the co-integration time.

 Next, the disadvantages of the constant integration time method are listed below.

(1) Since the constant-period pulse generated by the constant-period pulse generation circuit is not synchronized with the transport of the subject, the transport amount of the subject per integration time may be different. Therefore, even if the signal amount related to the amount of X-ray transmission obtained for each integration time is arranged according to the time axis, that is, in a time-series manner, the signal amount does not correspond to the position of the subject. The samples were only sampled at irregular intervals. Therefore, the position resolution at each point of the subject fluctuates, and it is impossible to measure the distance in the position movement direction of the subject, that is, the transport amount, from the signal amount of the X-ray transmission amount arranged in time series.

On the other hand, the fixed position moving method in which the integration time is set by the position pulse generated by the transport of the subject overcomes the drawbacks of the constant integration time method. .

(1) When the transport speed of the subject changes, the integration time also changes, and the amount of change in the integration time is directly reflected in proportion to the amount of the X-ray transmission signal. When the integration time exceeds a predetermined amount due to a delay in the transport speed, a problem such as an overflow in the X-ray detector occurs.

The present invention has been made in view of the above circumstances, and has as its object the fluctuation of the transport speed of the subject, the offset and gain of the X-ray detector are not affected, and the transport amount of the subject. An object of the present invention is to provide a fluoroscope capable of obtaining a signal amount related to a synchronized X-ray transmission amount.

[Configuration of the Invention] (Means for Solving the Problems) In order to achieve the above object, a fluoroscopic device of the present invention includes a radiation source that emits radiation toward a subject conveyed in one direction, and a radiation source Radiation detection means for outputting a detection signal relating to the radiation intensity of the radiation radiated from the object and transmitted through the subject; and carrier signal output means for detecting the carry amount of the subject and outputting a carry signal for each predetermined carry amount And a periodic signal output means for outputting a periodic signal for a fixed time at an interval shorter than the output interval of the carrier signal output from the carrier signal output means, and synchronized with the periodic signal output from the periodic signal output means. Then, the detection signal output from the radiation detection means is temporally integrated, and data obtained by the temporal integration is output in accordance with the carrier signal output from the carrier signal output means. It was constructed and a data output means for.

(Operation) In the fluoroscope according to the present invention, the subject is transported in one direction, and radiation is emitted from the radiation source toward the transported subject. Further, the radiation transmitted through the subject is detected by the radiation detecting means, and is output from the radiation detecting means as a detection signal relating to the radiation intensity. On the other hand, the transport amount of the subject is detected by the transport signal output means, and a transport signal is output for each predetermined transport amount.

In addition, a periodic signal output unit is provided, and the periodic signal output unit outputs the periodic signal at a time interval shorter than the output interval of the carrier signal output by the carrier signal output unit and for a fixed time.

Next, the data output means relates to the intensity of the radiation obtained by integrating the detection signal output from the radiation detection means during the output interval of the periodic signal output for a fixed time from the periodic signal output means. Data is selectively output only when a transport signal output in synchronization with the transport amount of the subject is output.

Embodiment First, a schematic configuration of the present invention will be described with reference to FIG.

The X-ray generator 1 and the X-ray detector 7 are provided between the X-ray generator 1 and the X-ray detector 7, and the collimator on the X-ray generator side.
3a, the subject 5 and the collimator 3b on the X-ray detector side are interposed and arranged in opposite directions.

The X-ray generator-side collimator 3a is disposed in the vicinity of the X-ray irradiation port of the X-ray generator 1 which is a radiation source of X-rays.
The X-ray emitted from the X-ray focal point 1a of the X-ray generator 1 is collimated into a desired shape, for example, a fan beam.

The X-ray detector-side collimator 3b is disposed on the front surface of the X-ray detector 7 on the X-ray generation device 1 side, and scatters X-rays that are a cause of disturbance, for example, emitted from the X-ray generation device 1. Intrusion of scattered radiation and the like toward the X-ray detector 7 into the X-ray detector 7 is prevented.

The data collection unit 9 is connected to the X-ray detector 7 and to an integration signal generation unit 19 described later, and outputs a detection signal detected by the X-ray detector 7 according to a signal from the integration signal generation unit. The data is collected and integrated over time, and data on the X-ray intensity obtained by the integration is output to the computer 11.

The computer 11 processes data relating to the X-ray intensity collected and output by the data collection unit 9.

The subject movement drive unit 15 is controlled by the subject movement drive control unit 13 so that the desired position of the subject 5 can be irradiated with the fan beam-shaped X-rays 1b emitted from the X-ray generator 1. The subject 5 is moved.

Synchronization signal generator connected to this subject movement driver 15
The reference numeral 17 generates a synchronization signal synchronized with the movement of the position of the subject 5 moved by the subject movement drive unit 15.

An integration signal generator 19 connected to the synchronization signal generator 17
Generates an integration signal for keeping the integration time in the data collection unit 9 constant, and outputs the integration signal to the synchronization signal generation unit.
The signal is output to the X-ray detector 7 and the data acquisition unit 9 in synchronization with the synchronization signal output from 17.

Next, the operation of the fluoroscope having the above-described configuration will be described along with the operation.

X-rays emitted from the X-ray focal point 1a of the X-ray generator 1
The X-ray is radiated from the X-ray emission port of the X-ray generator 1 and collimated into a fan beam-shaped X-ray 1b by the X-ray generator-side collimator 3a.

This fan beam-shaped X-ray 1b passes through a desired position of the subject 5 moved by the subject moving drive unit 15 from a desired direction, and is transmitted to the X-ray detector 7 via the X-ray detector-side collimator 3b. Incident.

At this time, a synchronizing signal is generated by the synchronizing signal generation unit 17 every time the position moves in synchronization with the movement of the subject 5, and is output to the integration signal generation unit 19. The integration signal generation section 19 outputs an integration signal for setting a fixed integration time to the X-ray detector 7 and the data collection section 9 in synchronization with the synchronization signal output from the synchronization signal generation section 17.

The X-ray detector 7 and the data collection unit 9 output a detection signal of an electric quantity according to the intensity of the incident X-ray to the integration signal generation unit.
Integrating in time the integration time set by the integration signal output from 19 to obtain data on the X-ray intensity and synchronizing with the input of the integration signal, that is, the data output from the synchronization signal generator 17. The data related to the X-ray intensity is output to the computer 11 in synchronization with the synchronization signal.

Next, an embodiment of the present invention will be specifically described with reference to FIG. The same or equivalent parts as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description is omitted.

The X-ray generator 1 includes an X-ray controller 1c and a high-voltage generator.
1d and an X-ray generator 1e. X-ray generator 1e
Is controlled by the X-ray controller 1c to control the high voltage generated by the high-voltage generator 1d, and
A predetermined tube voltage and a predetermined tube current are applied to the X-ray tube, and X-rays of a predetermined intensity are emitted from the X-ray focal point 1a toward the multi-channel X-ray detection unit 7a.

The multi-channel X-ray detector 7a is disposed opposite to an X-ray irradiator (not shown) of the X-ray generator 1e, and is configured by one-dimensionally arranging 512-channel detectors closely adjacent to each other.
Further, as a whole, the detection surface of the detector is arranged side by side on an arc centered on the X-ray focal point 1a.

Further, between the X-ray generator 1e and the multi-channel X-ray detector 7a, a belt conveyor 15c for transporting a long subject 5 such as a steel plate is provided. The belt conveyor 15c is an electric motor 15a that is driven to rotate according to the control of the conveyor drive control unit 13a.
The motor 15a is driven by a speed reducer 15b that reduces the rotational power of the electric motor 15a to an appropriate rotational speed.

Inside the belt conveyor 15c, an incremental type rotary encoder 17a for detecting the moving speed of the belt conveyor 15c is arranged, and detects the position movement amount of the belt conveyor 15c, that is, the transport amount of the subject 5. Thus, a transport pulse is output to a pulse synchronization circuit 19b described later for each predetermined transport amount La.

The square wave oscillator 19a generates a periodic pulse having a constant period Ta that is sufficiently shorter than the shortest period La of the carrier pulse output from the rotary encoder 17a, and outputs the pulse to the pulse synchronization circuit 19b.

The pulse synchronization circuit 19b synchronizes a synchronization pulse output from the square wave oscillator 19a at a constant cycle Ta with a rising edge of a carrier pulse output from the rotary encoder 17a, and outputs an integration signal to the data collection unit 9.

The data collection unit 9 is an X-ray detector that integrates a detection signal output from a connected 512-channel detector during the period of an integration signal output from the pulse synchronization circuit 19b for each detector. The data relating to the intensity is generated and output to the computer 11.

 Next, the operation of this embodiment will be described with reference to FIG.

The subject 5 is placed on the belt conveyor 15c and is transported by the belt conveyor 15c. Therefore, subject 5
Can be regarded as the same as the movement amount of the belt conveyor 15c. Next, X-rays 1b in the form of a fan beam are emitted to the subject 5 conveyed in this manner, and the X-rays transmitted through the subject 5 are transmitted.
The line is detected by the multi-channel X-ray detection unit 7a, and the transport amount of the subject 5 is detected from the moving amount of the belt conveyor 15c using the rotary encoder 17a. That is, a transport pulse is output to the pulse synchronization circuit 19b for each predetermined transport amount La of the subject 5. At this time, since the transport pulse is output in synchronization with the transport amount La, if the transport speed fluctuates, the temporal output interval of the transport pulse is not constant.

On the other hand, from the square wave oscillator 19a, a synchronization pulse of a square wave signal having a constant period Ta shorter than the shortest period of the carrier pulse output from the rotary encoder 17a is output to the pulse synchronization circuit 19b. The synchronization pulse Ta is set as an integration time in the data collection unit 9, and the integration time is uniquely determined by the periodic pulse, and is always constant. Further, when the rising of the carrier pulse is detected during the integration process in the data collection unit 9 for each integration time, the X-ray intensity related to the X-ray intensity obtained by the integration process within the integration time is determined. The data is transferred to the computer 11 in synchronization with the rise of the next periodic pulse. Therefore, fluoroscopic data can always be obtained for each predetermined transport amount La.

As described above, in the present embodiment, it is possible to always obtain the fluoroscopic data integrated only for a fixed integration time for each fixed transport amount La, without being affected by fluctuations in the transport speed of the subject. Perspective data can be obtained for each predetermined length of the subject.

Next, a second embodiment according to the present invention will be described with reference to FIG.

Since the configuration of the second embodiment can be configured in substantially the same manner as in FIG. 2, detailed description will be omitted. However, the square wave oscillator according to the present embodiment receives a carrier pulse output from the rotary encoder 17a and outputs a periodic pulse that maintains the “H” state for a fixed time Tb in synchronization with the rise of the carrier pulse. Things.

Therefore, according to the second embodiment, the periodic pulse and the carrier pulse rise synchronously, so that the integration is always started for each constant carry amount La, and after a certain integration time has elapsed, the periodic pulse rises. Data relating to the X-ray intensity is transferred to the computer 11 in synchronization with the downlink. Therefore, the X of the subject caused by the difference between the rise time of the periodic pulse and the rise time of the carrier pulse
An error in the line transmission position can be eliminated, and data with excellent position resolution can be obtained.

[Effects of the Invention] As described above, according to the present invention, the integration time is set to a fixed time by the synchronization signal output from the periodic signal output means, and the transport signal is provided for each predetermined transport amount of the subject. Synchronized with the transport signal output from the output means, even if the transport speed of the subject changes, the offset and gain of the X-ray detector are not affected, and the transport amount of the subject is not affected. A synchronized signal amount related to the X-ray transmission amount can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of the present invention, FIG. 2 is a schematic diagram showing an embodiment according to FIG. 1, FIG. 3 is a time chart for explaining the operation according to FIG. 5 is a time chart for explaining another embodiment, and FIGS. 5 and 6 are time charts for explaining a conventional example. DESCRIPTION OF SYMBOLS 1 ... X-ray generator, 3 ... Collimator 5 ... Subject, 7 ... X-ray detector 9 ... Data collection unit, 11 ... Computer 13 ... Subject movement drive control unit 15 ... Subject Moving drive unit 17 Synchronous signal generator 19 Integral signal generator

Claims (1)

(57) [Claims] 1. A radiation source that emits radiation toward a subject conveyed in one direction, and radiation detection means that outputs a detection signal related to the radiation intensity of the radiation emitted from the radiation source and transmitted through the subject. A carrier signal output unit that detects a carrier amount of the subject and outputs a carrier signal for each predetermined carrier amount; and an interval shorter than an output interval of the carrier signal output from the carrier signal output unit, and is constant. A periodic signal output means for outputting a periodic signal only for the time of: a detection signal output from the radiation detection means in synchronization with the periodic signal output from the periodic signal output means; And a data output means for outputting data obtained by integrating the data to the carrier signal output from the carrier signal output means.