JPH11204291A - X-ray photographing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a doctor to photograph at the optimum blackening degree even if a failure or a malfunction occurs on an X-ray automatic exposing circuit. SOLUTION: This device is provided with a current detector 10 time- integrating a current, X-ray exposure dose setting circuits (minimum value) 20, (maximum value) 40 setting the X-ray exposure doses per unit photograph to prescribed values, and signal generating circuits (a two-input AND circuit 30 and a two-input OR circuit 50) combining the output of the current detector 10, the outputs of the X-ray exposure dose setting circuits (minimum value) 20, (maximum value) 40, and the output of an output X-ray automatic exposing circuit 9 to generate the X-ray stop signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray imaging apparatus for performing X-ray imaging of an object using X-rays, and more particularly to an X-ray automatic exposure circuit for controlling the amount of X-rays emitted to the object. X-ray apparatus.

[0002]

2. Description of the Related Art Many conventional X-ray photographing apparatuses are equipped with an automatic X-ray exposure apparatus in order to improve the operability of the apparatus. This X-ray automatic exposure circuit automatically controls the imaging time among the X-ray imaging conditions, that is, the tube voltage (kV), the tube current (mA), and the X-ray emission time (sec), and improves the degree of blackening of the photograph. Was used to

In the X-ray imaging apparatus, the complexity of the operation of the operator such as a doctor for the X-ray imaging has been significantly reduced by the automatic X-ray exposure apparatus. In particular, the burden of setting the X-ray imaging conditions of the operator in a group examination in which an X-ray imaging apparatus is mounted on a car and moved to a remote place to photograph an unspecified number of subjects has been significantly reduced. .

[0004]

However, the automatic X-ray exposure apparatus cannot be said to have no failure or malfunction. For example, when the high voltage circuit of the photomultiplier tube fails and the applied voltage increases, the X-ray emission is stopped in a very short time and a photograph having a low degree of blackening is obtained. Further, if the cable connected to the X-ray detector breaks, the X-ray emission will be stopped in the maximum imaging time, so that there is a problem that a photograph having an excessive degree of blackening will result.

There is also a problem that the X-ray automatic exposure device may malfunction due to the slight discharge of the X-ray tube. In these cases, the obtained X-ray photograph cannot be interpreted and must be re-photographed.
There was also a problem from the viewpoint of an increase in radiation exposure and an increase in the workload of doctors and the like. In addition, multiplexing of the X-ray automatic exposure apparatus can achieve the same effect on these problems, but there is a problem that the cost is increased accordingly.

SUMMARY OF THE INVENTION The present invention has been made to solve at least one of the above problems, and enables a doctor or the like to take a photograph with an optimum degree of blackening even if a failure or malfunction occurs in an X-ray automatic exposure circuit. It is intended to provide a device.

[0007]

According to the present invention, there is provided an X-ray imaging apparatus having an X-ray automatic exposure circuit for controlling a time for supplying each of a voltage and a current of an X-ray tube. A current integration circuit for integrating the current with time, an X-ray radiation amount setting circuit for setting the amount of X-ray radiation per unit imaging to a predetermined value, an output signal of the integration circuit and an output signal of the X-ray radiation amount setting circuit. A signal generating circuit for generating an X-ray stop signal by combining output signals of the X-ray automatic exposure circuit.

More specifically, the integrating circuit integrates the current of the X-ray tube and outputs a signal corresponding to the mAs value. On the other hand, the signal corresponding to the mAs value is set to the minimum value of the amount of X-ray radiation per unit radiography. For example, it is possible to read the mAs even if the degree of blackening of the X-ray photograph is not the optimum value.
Set the signal corresponding to the minimum value of. A first comparison circuit compares the output of the integration circuit with the minimum value of mAs. The first comparison circuit outputs an H-level signal when the output of the integration circuit is equal to or greater than the minimum value of mAs, and outputs an L-level signal when the output is less than the minimum value of mAs. Input to one input terminal. The output signal of the X-ray automatic exposure circuit is input to the other input terminal of the two-input AND circuit.

On the other hand, the signal of the integrating circuit is compared with the maximum value of the amount of X-ray radiation, for example, the maximum value of mAs at which the degree of blackening of the X-ray photograph is not excessive and the image can be read somehow by the second comparing circuit. You. When the output of the integrator circuit is equal to or less than the maximum value of mAs, an L-level signal is output.
A level signal is output and input to one input terminal of a two-input OR circuit connected to the subsequent stage. The output of the AND circuit is input to the other input terminal of the two-input OR circuit. This OR circuit is output as an X-ray emission stop signal.

As described above, the two-input AND circuit and the two-input OR
By providing a signal generation circuit formed by a circuit or the like, even if a failure or malfunction occurs in the X-ray automatic exposure circuit, a doctor or the like can take a photograph with an optimal degree of blackening.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an inverter type X of this embodiment.
FIG. 2 is a block diagram illustrating a main part of the radiographic apparatus.

The inverter type X-ray imaging apparatus includes a DC power source 1
And an inverter circuit 2 electrically connected to a two-input OR circuit 50 that receives an X-ray emission command S1 and outputs an X-ray stop command S2, and a high-voltage transformer electrically connected to the inverter circuit 2. 3, a rectifier circuit 4 electrically connected to the high-voltage transformer 3, a tube current detector 10 electrically connected to the rectifier circuit 4, and an X-ray electrically connected to the tube current detector 10. A minimum radiation amount setting circuit 20, an automatic X-ray detection circuit 9 electrically connected to the tube current detector 10 and the X-ray detector 8, and an X-ray radiation electrically connected to the tube current detector 10. X-ray tube 5 electrically connected to rectification circuit 4 and tube current detector 10, X-ray radiation minimum value setting circuit 20 and X-ray automatic detection circuit 9 Connected two-input AND circuit 30 and two-input A
It has a two-input OR circuit 50 electrically connected to the ND circuit 30 and the maximum X-ray radiation amount setting circuit 40. Further, a film 7 is disposed at a position facing the X-ray tube 5 and the subject 6. An X-ray detector 8 is arranged in the direction opposite to the X-ray incidence on the film 7.

The DC power supply 1 is composed of a commercial power supply for outputting a DC voltage by a rectifier circuit, a battery, and the like. The inverter circuit 2 converts a DC voltage input from the DC power supply 1 into a high-frequency AC voltage and outputs it. The high-voltage transformer 3 boosts the AC voltage input from the inverter circuit 2 to a voltage that can be applied to the X-ray tube. The rectifier circuit 4 converts an AC voltage input from the high-voltage transformer 3 into a DC voltage. The X-ray tube device 5 includes a tube voltage supplied from the rectifier circuit 4,
X-rays are emitted to the subject 6 based on the tube current. Film 7
Is irradiated onto the subject 6 from the X-ray tube 5 and is exposed to X-rays transmitted through the subject 6 to form an X-ray image. X-ray detector 8
Outputs an electric signal corresponding to the intensity of the X-ray transmitted through the subject 6. This output is output to the X-ray automatic exposure circuit 9. The power supply to the X-ray tube device 5 is performed via a high-voltage cable. In order to measure a current (tube current) flowing through the high-voltage cable, a tube current detector 10 is provided. Are connected to the X-ray irradiation minimum value setting circuit 20 and the X-ray irradiation maximum value setting circuit 40. Then, the outputs of both the X-ray automatic exposure circuit 9 and the X-ray irradiation minimum value setting circuit 20 are input to the two-input AND circuit 30. Further, both the output of the two-input AND circuit 30 and the output of the X-ray irradiation maximum value setting circuit 40 are input to the two-input OR circuit 50. The output S2 of the two-input OR circuit 50 is configured to be input to the inverter circuit 2 as an X-ray stop command. The signal S1 is a signal generated when an operator operates an X-ray imaging switch to start X-ray imaging. The signal S1 is a command signal for alternately turning on two pairs of switching elements of the inverter circuit 2, and a signal S2. Is a command signal for turning off the switching element in order to stop X-ray irradiation.

Next, an example of a detailed configuration of the X-ray irradiation minimum value setting circuit 20 and the X-ray irradiation maximum value setting circuit 40 will be described with reference to FIG. In FIG. 2, a tube current time integration circuit 21 integrates a signal input from the tube current detector 10 with time by an integrator IC1 and outputs the integrated signal. The output signal is a mAs value of the tube current and X It corresponds to the product mAs of the elapsed time from the start of the line emission to the second (sec).

In the present embodiment, the X-ray radiation minimum value setting circuit 22 is capable of setting two types of surgical methods, for example, indirect chest radiography and direct chest radiography. It has PS2 and volumes VR1 and VR2. By setting these volumes VR1 and VR2 to appropriate values, the magnitude of the output signal of this circuit can be changed. In this embodiment, the minimum mAs value in one film shooting is set by the volume. The minimum value comparison circuit 23 includes a tube current time integration circuit 21
Is compared with the output signal of the X-ray emission minimum value setting circuit 22. Usually, a low (L) level signal is output, and the output signal of the tube current time integration circuit 21 is When it matches the output signal of the minimum quantity value setting circuit 22, a high (H) level signal is output. PS3 is a push button switch operated when taking a picture using the X-ray automatic exposure circuit 9. The two-input AND circuit 30 corresponds to FIG.
Is an AND gate circuit shown in FIG. The output signal of the tube current time integration circuit 21 has an output line of a signal for generating an X-ray emission stop command by mAs value control.

In the present embodiment, the maximum X-ray radiation dose setting circuit 42 is capable of setting two surgical procedures, for example, indirect chest radiography and direct chest radiography. It has PS2 and volumes VR3, VR4. By setting these volumes VR3 and VR4 to appropriate values, the magnitudes of the output signals of these circuits can be changed. In the present embodiment,
MAs in one film shooting by volume
Set the maximum value of The maximum value comparison circuit 43 compares the output signal of the tube current time integration circuit 21 with the output signal of the X-ray emission maximum value setting circuit 42, and normally outputs a low level signal. When the output signal of the time integration circuit 21 exceeds the output signal of the X-ray emission maximum value setting circuit 42, a high-level signal is output.

Next, the operation of the present apparatus will be described. The operator first decides on what kind of imaging method he or she will perform,
Pressing the operative method selection PS1 or PS2, and the volume VR1 or VR2 connected to the operative method switch,
By operating VR3 or VR4, the required minimum mAs value required for one film shooting and the required maximum mAs value
Set a value. For the purpose of this setting, the mAs value can be graduated according to the rotation angle of the volume knob. When this setting is completed, the push button switch PS3 is pressed to perform X-ray automatic exposure photography. As a result, the output signal of the minimum value comparison circuit 23 is output to the AND gate circuit 3
0, so that the output signal of the maximum value comparison circuit 43 can be input to the OR gate circuit 50.

Next, the operator sets an imaging tube voltage, operates an imaging switch, and issues an X-ray emission command S1. This X
The line radiation command S1 activates the inverter circuit 2 to convert the voltage input from the DC power supply 1 into a high-frequency AC voltage and input it to the high-voltage transformer 3. The output of the high-voltage transformer 3 is rectified and applied to the X-ray tube 5, and the subject 6 is irradiated with X-rays.

The current flowing through the X-ray tube 5 during X-ray emission is detected by a tube current detector 10, and the detected signal is input to a tube current time integration circuit 21. , And the integrated value is output as a mAs signal. On the other hand, the X-ray emission minimum value setting circuit 22 continues to output a signal corresponding to the set minimum value of mAs, and these two signals are used as the minimum value comparison circuit 23.
Are compared. When these two signal values become the same level, the output signal from the minimum value comparison circuit 23 becomes high level, and the high level signal is input to the two-input AND circuit 30 via PS3. The X-ray automatic exposure circuit 9 also counts the output signal of the X-ray detector 8 together with the start of X-ray emission, and if it operates normally, stops X-ray emission when the X-ray film reaches a predetermined degree of blackening. Output a signal.
However, it is assumed that the X-ray emission stop signal is output after a very short time has elapsed since the start of X-ray emission due to malfunction. Under this assumption, an X-ray emission stop signal is output from the X-ray automatic exposure circuit 9 earlier than the output signal of the minimum value comparison circuit 23 becomes high level. However, the signal is output from the two-input AND circuit 30 when the output signal of the minimum value comparison circuit 23 becomes high level. The signal output from the two-input AND circuit 30 passes through the two-input OR circuit 50, is input to the inverter circuit 2 as the X-ray emission stop signal S2, and the operation of the inverter circuit 2 is stopped.

It is also assumed that an X-ray emission stop signal is not output from the X-ray automatic exposure circuit 9 due to a failure of the X-ray automatic exposure circuit 9. Under this assumption, no high-level signal is output from the two-input AND circuit 30. On the other hand, the X-ray emission maximum value setting circuit 42 continues to output a signal corresponding to the set mAs value, and this and the tube current time integration circuit 2
1 is compared by the maximum value comparing circuit 43. And
When these two signal values become the same level, the output signal from the maximum value comparison circuit 43 becomes high level, and the high level signal is output to the two-input OR circuit 50 via PS3.
Enter The two-input OR circuit 50 is the other two-input A
Even if there is no input signal from the ND circuit 30, the X-ray emission stop signal S2 is output when the output signal from the maximum value setting circuit 43 is output.

The series of operations described above completes the X-ray photography of one film. In the conventional apparatus, since the X-ray automatic exposure circuit is not backed up, an X-ray photograph which cannot be read by a doctor because the film does not have a predetermined degree of blackening or the photograph has an excessive degree of blackening. In some cases, shooting is performed, but this can be prevented in the present invention.

The present embodiment is not limited to the above-described embodiment, but can be variously modified. As an example, the mAs value of the X-ray radiation amount is used, but other than that, the imaging time can be used. In that case, a timekeeping circuit may be provided in place of the tube current time integration circuit, and the timekeeping circuit may be operated according to the X-ray emission command S1 to generate a signal by comparison.

As described above, according to the present embodiment,
Even if the X-ray automatic exposure circuit outputs an X-ray emission stop signal in a very short time or an excessively long time due to malfunction or failure, the X-ray emission minimum value setting circuit or the X-ray emission maximum setting circuit X backed up and readable by doctors
A radiograph is obtained. The same effect can be obtained by multiplexing the X-ray automatic exposure circuit and creating the logic by the OR circuit. However, the X-ray automatic exposure circuit is more expensive than the X-ray radiation amount minimum and maximum value setting circuit. According to the present invention, the cost can be reduced.

[0024]

The present invention has the effect of providing an X-ray imaging apparatus that enables a doctor or the like to take a picture with an optimum degree of blackening even if a failure or malfunction occurs in the X-ray automatic exposure circuit.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of an X-ray imaging apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a signal generation circuit that generates a combination signal of the X-ray automatic exposure circuit and the comparison circuit of FIG. 1;

[Explanation of symbols]

 23 Minimum value comparison circuit 30 2-input AND circuit 43 Maximum value comparison circuit 50 2-input OR circuit

Claims (1)

[Claims] 1. An X-ray imaging apparatus comprising an X-ray automatic exposure circuit for controlling a time for supplying each of a voltage and a current of an X-ray tube.
An X-ray radiation amount setting circuit for setting the amount of X-ray radiation per unit imaging to a predetermined value; a combination of an output signal of the integration circuit, an output signal of the X-ray radiation amount setting circuit, and an output signal of the X-ray automatic exposure circuit An X-ray imaging apparatus comprising a signal generation circuit for generating an X-ray stop signal.