JPH0675440B2 - X-ray equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an X-ray device, and more particularly to protection of an X-ray tube device, which is suitable for controlling the amount of heat applied to the X-ray tube device and the X-ray tube anode. The present invention relates to a technique for accurately managing the X-ray tube device so as not to shorten the life or damage the X-ray tube device due to a thermal factor.

[Prior art]

The heat management of the conventional X-ray tube device mainly focuses on the amount of heat applied to the X-ray tube anode, and aims to prevent the anode of the X-ray tube from being thermally deteriorated or melted. It is a thing. Most of the load management of the X-ray tube of the X-ray tube apparatus is a method of allowing the single shot imaging condition with a value obtained by reducing the maximum allowable value by a certain value.

This conventional method is a predictive control, and when the X-ray load used for the allowable load value of the X-ray tube is low and the use repetition frequency is low, control can be performed without exceeding the thermal allowable value. However, in the recent usage of X-ray tubes used for gastrointestinal diagnosis and circulatory system diagnosis, the X-ray load for each time is close to the allowable value, and the frequency of repetition is very high.

Further, considering the heat source of the entire X-ray tube device containing the X-ray tube, not only the heat generation of the anode during X-ray radiation but also the power consumed by the stator coil for rotating the anode, or To reduce bearing wear due to inertial rotation, the amount of heat generated by the power consumption of the electric brake that stops the rotating anode is comparable to the amount of heat generated by the X-ray anode, and the amount of power consumed by the filament is small but ignored. It cannot be done. These heats increase the temperature of the entire X-ray tube device and also the temperature of the cooling insulating oil, which deteriorates the heat radiation of the X-ray tube anode, which promotes the thermal deterioration of the anode and the rotary bearing. Since the wear of the lubricant of the portion is accelerated, it causes the rotation failure of the anode. Further, the deterioration of the insulating grease of the high voltage plug and the socket is promoted, which causes a high voltage discharge.

Therefore, in the conventional temperature control of the entire X-ray tube device, the temperature of the cooling insulating oil is monitored by a detector provided on the anode side or the cathode side.

[Problems to be solved by the invention]

However, in the conventional temperature control of the entire X-ray tube device, only the temperature of the cooling insulating oil is monitored by the detector provided on the anode side or the cathode side, and the temperature is detected depending on the posture of the X-ray tube used. There is a problem in that there is a difference in temperature and the like, which is not sufficient as a method of monitoring the thermal state of the entire X-ray tube device.

Further, in the conventional temperature control method for the entire X-ray tube device,
Since the residual amount of heat to the anode of the X-ray tube is not taken into consideration, there is a problem that the X-ray tube may be damaged by exceeding the thermal allowable value.

Also, in consideration of the thermal time constant of the X-ray tube, some measures have been taken to change the reduction rate from the maximum allowable heat value of the X-ray tube according to the amount of remaining heat. Since only the conditions of the above are managed and the amount of heat due to the fluoroscopic conditions is not considered, it is necessary to stop them during the series of fluoroscopy / imaging necessary for the diagnosis of one subject. was there.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to ensure the thermal management of the entire X-ray tube device to prevent the failure of the X-ray tube and the X-ray tube device. It is an object of the present invention to provide a technique capable of reducing the number of the X-ray tubes and the X-ray tube apparatus and prolonging their service lives.

Another object of the present invention is to interrupt the diagnosis due to a sudden operation of the temperature limiter, which is caused by a lack of operational consideration such as providing some pauses in the diagnosis time between the subject and the next subject, and sudden It is to provide a technique capable of avoiding discontinuation of diagnosis due to tube damage.

The above and other objects and novel features of the present invention will be described with reference to the following description of the present specification and the accompanying drawings.

[Means for solving problems]

The following is a brief description of the outline of the typical inventions among the inventions disclosed in the present application.

That is, an X-ray device equipped with a circuit for respectively detecting an X-ray tube voltage, an X-ray tube current, an X-ray load time, an anode drive power, a brake power, and a filament power, wherein X signals are detected from the detected signals. Calculation storage means for calculating and storing the amount of heat applied to the tube device, and integrated storage for storing the calculation result by sequentially adding the amount of heat generated for each fluoroscopy / imaging to the stored value calculated up to the previous time. Means, the cumulatively stored heat quantity is matched with the cooling rate of the total thermal characteristics of the X-ray tube device, subtracted with time, and the subtraction storage means for storing the result, and the heat quantity stored in the subtraction storage means. A comparison means for sequentially comparing the value A with the maximum allowable value B of the X-ray tube stored separately, and when the value A of the heat quantity reaches a predetermined value C lower than the value B, the first signal When the value A of the heat quantity exceeds the value B , And a signal generating means for generating the second signal.

[Action]

According to the means described above, the tube voltage actually applied to the X-ray tube, the load time, and the tube current that actually flowed are detected together with the imaging and fluoroscopic modes, and the X-ray tube input is set to "HU" (heat unit).
Or calculated as "Ws" (Watts second), and most of the stator starting power, braking power, and filament heating power are also heat sources of the X-ray tube device temperature rise. It is added to the calculated stored value, the added result is matched with the cooling rate of the total thermal characteristics of the X-ray tube device and subtracted with time, and the subtracted result is sequentially stored as the residual heat amount of the X-ray tube device. In addition, the maximum allowable value stored separately for each X-ray tube type is compared with the calculation result, and when the calculation result reaches the first certain value lower than the maximum allowable value, the first warning signal is generated. The second warning signal is generated when the accumulated heat further exceeds the allowable maximum value and the X-ray emission for imaging or fluoroscopy which is currently performed is completed.

The first warning signal gives a warning to the operator that the residual heat quantity is approaching the maximum allowable value, and the second warning signal gives a warning that X-ray radiation is not possible and protects the X-ray tube device. Therefore, the above object is achieved by interlocking X-ray radiation, rotation of the X-ray tube anode, and the like.

Example of Invention

An embodiment of the present invention will be specifically described below with reference to the drawings.

In all the drawings for explaining the embodiments, parts having the same function are designated by the same reference numerals, and repeated description thereof will be omitted.

1 is a block diagram showing a schematic configuration of an X-ray apparatus according to an embodiment of the present invention, FIG. 2 is a block diagram showing a configuration of a tube current / X-ray emission time detection circuit shown in FIG. FIG. 3 is a block diagram showing the configuration of the tube voltage detection circuit shown in FIG. 1, and FIG. 4 is a diagram showing tube voltage characteristics.

In FIGS. 1 to 3, reference numeral 1 is an autotransformer that determines an X-ray tube voltage, and a brush 2 sets a predetermined tube voltage. 3 is an X-ray switch for turning on and off X-ray radiation, 4 is a main transformer for boosting, 5 is a high voltage side neutral point terminal for measuring tube current and X-ray load time, 6 is a high-voltage rectifier, and 7 is an X-ray tube. 8 is an exciting coil of the X-ray switch 3, 9 is an X-ray from an X-ray emission control circuit such as an imaging timer.
A contact that operates in ON-OFF signal S _4.

As the X-ray switch 3, an SCR or a tetrode tube is used, but an electromagnetic X-ray switch is used for ease of explanation.

Reference numeral 10 denotes a tube current / X-ray emission time detection circuit, which has a circuit configuration as shown in FIG.

In FIG. 2, the tube current flowing into the high voltage side neutral point terminal 5 is rectified by the rectifier 20 and converted into a voltage by the detection resistor 21. The voltage waveform has a waveform as shown by reference numeral 23. Since the X-ray tube circuit can be regarded as a current source, the tube current value does not change even if a small amount of the detection resistor 21 is connected to the neutral point.

The voltage is input to the averaging circuit 22 and averaged to become a voltage proportional to the tube current (mM) having a waveform as indicated by reference numeral 25. This voltage is digitized by an analog / digital (A / D) conversion circuit 24.

On the other hand, the time from when the tube current starts to flow to when it ends is detected as the X-ray emission time (s), and is similarly sent to the next stage as a digital signal.

Here, the method of detecting the tube current from the high-voltage side neutral point terminal 5 has been described, but a method of detecting the current actually flowing in the anode of the X-ray tube with a hall element or the tube current with respect to a preset value If it is corrected sufficiently, there is no practical problem even if this preset value is used as the tube current.

Reference numeral 11 is a tube voltage detection circuit, which has a circuit configuration as shown in FIG.

In FIG. 3, the voltage of the brush 2 of the autotransformer 1 is transformed by the insulating transformer 30 and converted into direct current by the rectifying / smoothing circuit 31. This DC voltage is input to the tube voltage precalculation calculation circuit 33, and converted into a voltage proportional to the tube voltage using the selected tube current signal 32 as a parameter. This tube voltage detection circuit 11
Is calculated so that the tube voltage value for each tube current is output by inputting the no-load temporary voltage of the main transformer 4, as shown in FIG. This calculation can also be performed by a calculation circuit using a microcomputer or the like. The output of the tube voltage indication calculation circuit 33 is A / D converted by the analog / digital (A / D) conversion circuit 34 and sent to the next stage as a tube voltage signal (kV).

The anode accumulated heat quantity HU ₁ of the X-ray tube is calculated by the following equation (1), for example, in a two-peak rectification type high voltage device.

HU ₁ = tube voltage (kV) x tube current (mA) x time (s) ...
(1) 12 is a first calculation circuit, which performs calculation by the formula (1) for each X-ray radiation, and inputs the result to the third calculation circuit 13 in the next stage.

Wa is the stator start-up power signal consumed at one time, and X
If the type of wire tube and its anode drive device are determined, the power required for one start can be considered to be almost constant. Wb is a brake power signal consumed at one time, and it can be considered that the power consumption at one time is also constant like the stator start power signal Wa. Wf is the filament power per unit time, and the power consumption itself is 15 to 25 [Watts per second: W / s], but since the filament is lit continuously, the calorific value cannot be ignored.

Here, the signals Wa, Wb, and Wf were thought that 100% of the applied power became heat, but in reality, there are some parts that do not become heat, such as the energy for rotating the anode of the X-ray tube. To be strict, there is also a method of subtracting the effective part. However, even if it is considered that 100% of the heat is generated, there is no problem in practical use, and there is also the effect that the calculation result will be on the safe side.
Since there is a relationship of 1HU = 0.71Ws between the electric energy and the heat unit HU, the total heat unit of the signals Wa, Wb, Wf is HU.
_{If 2} , then HU ₂ = (Wa × N + Wb × N + Wf × s) ÷ 0.71 (2) holds. Here, N is the number of times of activation (corresponding to the number of times of braking), and s is the lighting time of the filament.

SS is a stator start signal, and the number N of starts is calculated from this signal SS. FS is a filament lighting signal, and is for calculating and adding Wf at regular time intervals while the signal FS is being input. Reference numeral 14 is a second calculation circuit that executes the calculation of equation (2), and the calculation result is the third calculation circuit.
It is input to the calculation circuit 13.

On the other hand, the amount Hua of heat remaining in the X-ray tube device is HHa _-1 , the amount of heat remaining up to the previous calculation, and the amount of heat added in this calculation is H
If U ₁ + HU ₂ , the calculation interval is t, and the cooling constant determined by the X-ray tube type, cooling method, etc. is T, then HUa = (HUa ₋₁ + HU ₁ + HU ₂ ) e ^{−t / T} (3). e is the base of the natural logarithm.

The third calculation circuit 13 is a circuit that executes the calculation of equation (3), and calls the calculation result up to the previous time from the first storage circuit 15 and stores the calculation result this time in the first storage circuit 15. is there. The second storage circuit 16 stores the maximum allowable heat storage amount for each X-ray tube type, and can be freely called by the X-ray tube type selection signal XTS.

The values of the first and second storage circuits 15 and 16 are periodically compared by the comparison / control circuit 17 to monitor the residual heat amount of the X-ray tube device.

Then, in the comparison / control circuit 17, first, the warning signal S ₁ is generated at a predetermined value lower than the allowable maximum heat quantity by a constant rate, and the warning indicator lamp 18 is driven to display the warning. This informs the operator that the amount of residual heat is approaching the allowable value. It is also possible as another application example to display the ratio of the calculation result and the allowable value in% for this notice. For the reduction rate, a value suitable for the operative method is selected according to the used operative method (imaging method) signal PS. It is set in advance to a value that does not need to be interrupted.

Further, immediately after the residual heat amount increases and exceeds the allowable amount and the X-ray emission at that time is stopped, the X-ray emission interlock signal S ₂ is generated, and the X-ray emission interlock device 19 is driven to drive the X-ray emission. Interlock. Along with this interlock, supply of starting power to a stator (not shown) is also stopped. The reason why the interlock signal is not generated during X-ray emission is to prevent interruption of photography and fluoroscopy.

The apparatus according to the present embodiment periodically executes the calculation of the equation (3) even after the X-ray radiation interlock signal S ₂ is generated, and the residual heat quantity gradually decreases, and the value decreases to a certain value. Then, the notice signal S ₁ and the release signal S ₃ for releasing the X-ray emission interlock signal S ₂ are generated. It is considered practical that a certain value for generating the release signal S ₃ is set to such an extent that it can be used by one subject when the use is resumed.

The first to third calculation circuits 12, 13, 14 and the first and second storage circuits 15, 16 and the comparison / control circuit 17 are easily realized by using a control device such as a microcomputer (not shown). it can.

Also, by backing up the battery, even after the main power is turned off,
The amount of residual heat can be monitored.

In FIG. 1, the stator start signal SS, the stator start power signal Wa, the brake power signal Wb, the filament heating power signal Wf, the filament lighting signal FS, etc. can be easily read from the conventional X-ray controller and high voltage generator. Therefore, the description of those specific means will be omitted here.

As can be seen from the above description, according to this embodiment, the following operational effects are exhibited.

The tube voltage that is actually applied to the X-ray tube, the load time, and the tube current that actually flowed are detected together with the imaging and fluoroscopic modes, and the X-ray tube input is "HU" (heat unit) or "Ws" (watt second). Then, most of the stator starting power, braking power, and filament heating power are also used as the heat source for the temperature rise of the X-ray tube device, and each time that heat is generated, it is added to the value calculated and stored up to the previous time. Then, the added result is matched with the cooling rate of the total thermal characteristics of the X-ray tube device, subtracted with time, and the subtracted result is sequentially stored as the residual heat amount of the X-ray tube anode, and for each type of X-ray tube. The calculation result is compared with the separately stored maximum allowable value, and when the calculation result reaches the first predetermined value of the allowable maximum anode accumulated heat quantity, the first
When the X-ray emission for radiography or fluoroscopy, which is currently being performed, is finished, the second warning signal is generated, and the first warning signal is generated. The warning signal gives a warning to the operator that the residual heat amount is approaching the maximum allowable value, and the second warning signal gives a warning notifying that X-ray radiation is not possible and also protects the X-ray tube. Therefore, since the X-ray radiation is interlocked, a series of fluoroscopic imaging necessary for diagnosing the subject can be continuously performed within the range of the allowable value of the X-ray tube.

Further, this makes it possible to prevent the X-ray tube from being melted due to excess heat applied to the X-ray tube with a simple structure, and the failure of the X-ray tube such as defective rotation of the anode and the shortening of the service life. Therefore, the life of the X-ray tube can be extended.

In addition, by giving advance notice that the X-ray radiation will be interlocked, the operator may overload the X-ray condition, the radiation interval, etc. in order to smoothly diagnose the subject. Since consideration can be given to the operation so that the diagnosis is not interrupted, a series of fluoroscopic imaging necessary for the diagnosis of the subject can be continuously performed within the range of the allowable value of the X-ray tube.

Further, since the abnormal heating of the X-ray tube device is prevented by generating the X-ray radiation interlock signal, the heat radiation of the anode is smoothly performed, and the wear of the lubricant of the anode rotary bearing portion can be suppressed, and the high pressure can be suppressed. Since the deterioration of the insulating grease of the plug and the socket, which is the connection point with the cable, is suppressed, the life of the X-ray tube device can be extended.

Further, in the subtraction, the calculation is continuously performed even while the X-ray emission is stopped, and the subtraction result (residual heat amount) reaches the second predetermined value smaller than the allowable maximum anode accumulated heat amount including the first predetermined value described above. When this occurs, a third signal is generated and the first warning signal and the second warning signal are stopped, so that a series of fluoroscopic imaging can be performed with a margin with respect to the allowable value of the X-ray tube, and there is a margin. The fluoroscopic imaging can be restarted at a cooling time interval that is about the time of replacement of the subject.

The present invention has been specifically described above based on the embodiments.
It is needless to say that the present invention is not limited to the above-mentioned embodiments and can be variously modified without departing from the scope of the invention.

For example, the first, second and third signals can be used as control reference signals for other operations required for diagnosis. For example, the first signal can be used as a control reference signal for the operation of administering a contrast agent or the like.

〔The invention's effect〕

As described above, according to the present invention, the following effects can be obtained.

(1) By ensuring the thermal management of the entire X-ray tube device, the failure of the X-ray tube and the X-ray tube device can be reduced, and the life of the X-ray tube and the X-ray tube device can be extended.

(2) By giving advance notice that the X-ray radiation will be interlocked, the operator may overload the X-ray condition, radiation interval, etc. in order to perform the diagnosis of the subject without delay. Since consideration can be given to the operation so that the diagnosis is not interrupted, a series of fluoroscopic imaging necessary for the diagnosis of the subject can be continuously performed within the range of the allowable value of the X-ray tube.

(3) Since abnormal heating of the X-ray tube device is prevented by generating the X-ray radiation interlock signal, heat dissipation of the anode is smoothly performed, wear of the lubricant in the anode rotary bearing portion can be suppressed, and high pressure can be achieved. Since the deterioration of the insulating grease at the plug and the socket, which is the connection point with the cable, is suppressed, the life of the X-ray tube device can be extended.

[Brief description of drawings]

1 is a block diagram showing a schematic configuration of an X-ray apparatus according to an embodiment of the present invention, FIG. 2 is a block diagram showing a configuration of a tube current / X-ray emission time detection circuit shown in FIG. FIG. 3 is a block diagram showing the configuration of the tube voltage detection circuit shown in FIG. 1, and FIG. 4 is a diagram showing tube voltage characteristics. In the figure, 1 ... autotransformer, 2 ... brush, 3 ... X-ray switch, 5 ... high-voltage side neutral point terminal, 7 ... X-ray tube, 10 ...
Tube current / X-ray emission time detection circuit, 11 …… Tube voltage detection circuit, 12 …… First calculation circuit, 13 …… Third calculation circuit, 14 ……
Second calculation circuit, 15 ... First memory circuit, 16 ... Second memory circuit, 17 ... Comparison / control circuit, 18 ... Warning indicator light, 19 ...
X-ray radiation interlock device, Wa …… stator start power signal, Wb …… brake power signal, Wf …… filament heating power signal, SS …… stator start signal, FS …… filament lighting signal, S ₁ …… preliminary signal , S ₂ ... X-ray radiation interlock signal, S ₃ ... release signal, S ₄ ... X-ray ON-OFF signal.

Claims (1)

[Claims] 1. An X-ray device having a circuit for detecting an X-ray tube voltage, an X-ray tube current, an X-ray load time, an anode driving power, a brake power and a filament power, respectively. Calculation storage means for calculating and storing the amount of heat applied to the X-ray tube device from the signal, and storing the calculation result by sequentially adding the amount of heat generated for each fluoroscopy / imaging to the storage value calculated up to the previous time. And a subtraction storage unit that stores the result by making the accumulated storage amount of heat correspond to the cooling rate of the total thermal characteristics of the X-ray tube device and subtracting it with time, and storing it in the subtraction storage unit. And the heat quantity value A,
Comparing means for sequentially comparing the separately stored allowable maximum value B of the X-ray tube with each other, and generating a first signal when the heat quantity value A reaches a predetermined value C lower than the value B, An X-ray apparatus comprising a signal generating means for generating a second signal when the value A of the heat quantity exceeds the value B.