JPH03205794A - X-ray control device - Google Patents

Abstract

PURPOSE:To easily obtain a photographed film in the desired exposure state by inputting the time information obtained by adding/subtracting the compensation time into a timing means so as to make the film exposure state constant, and limiting the time of the applied voltage to the primary side of a high- voltage transformer. CONSTITUTION:When photographing conditions including the photographing time, tube voltage and tube current are set to this device so that a photographed film is set to the desired exposure state, a time control means 8 determines the compensation time so that the film exposure state is made constant based on the preset photographing condition information. The time added/subtracted with the compensation time thus determined to/from the preset photographing time is inputted to a timing means 11 as the time information, and the timing means 11 limits the time of the applied voltage to the primary side of a high- voltage transformer 4 based on the inputted time information. The high voltage outputted from the secondary side of the high-voltage transformer 4 is controlled, and the photographed film with the exposure state desired by an operator is obtained.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is an X-ray control device used in an X-ray imaging system to control the voltage applied to the primary side of a high voltage transformer. Regarding
More specifically, the present invention relates to an improvement in a method for controlling film exposure conditions.

(Prior Art) A conventional X-ray control device converts a high voltage transformer into The high voltage from the secondary side of the high voltage transformer is applied to the X-ray tube through the high voltage cable.

By the way, if the waveform of the high voltage output from the secondary side is a regular rectangular waveform, the application time of the high voltage output from the secondary side will be equal to the set shooting time, and the shooting time will be the same. It would also be possible to expose the film to the desired exposure state by the operator.

However, as shown in Figure 4(a), on the primary side? Since the high voltage is applied to the X-ray tube via the high voltage cable, the high voltage waveform output from the secondary side for the time t1 of the applied voltage is as shown in Fig. 4(b). , sagging occurs at the rising portion Wf and falling portion wb due to the stray capacitance of the high voltage cable and the internal impedance of the X-ray tube. In particular, the characteristics of the falling portion Wb0 are worse than those of the rising portion Wf.

If the lowest voltage that can contribute to film exposure is V, then the time Te■ that contributes to film exposure is shown in Figure 4 (
As shown in b), the time is the sum of the set photographing time t1 and the exposure contribution time Δt1 at the wave tail.

On the other hand, this falling characteristic changes depending on the tube voltage, tube current, length of the high voltage cable, etc. That is, the higher the tube voltage, the longer the fall time, the higher the tube current, the shorter the fall time, and the longer the high voltage cable, the longer the fall time.

Therefore, as shown in FIGS. 5(a) to CC'), even if the same imaging time t2 is set, the state of the wave tail changes due to the difference in tube voltage or tube current, and the total exposure contribution time Te2
, Te3 changes. In other words, as shown in FIG.
Assuming that the total exposure contribution time is Te2, the exposure contribution time of the wave tail at the time of low voltage setting is shortened to Δt3, and the total exposure contribution time is shortened to Te3. For this reason, the film exposure state differs between the two.

Other factors that contribute to film exposure include the thickness of the subject (hereinafter referred to as the "human body"), the X-ray attenuation rate on the imaging table, the internal impedance of the X-ray tube, and the sensitivity of the film used. Photography conditions were selected by intuition based on these complex conditions.

For example, when first photographing an overweight person to obtain a film with the desired exposure, the next photograph is of a person whose body thickness requires half the amount of X-rays compared to the previous person. Then, as shown in FIG. 6(a), the operator sets the shooting time to the 4th? Photographing is performed by selecting half of the photographing time t1 shown in (a), t1/2.

However, in reality, since there is a wave tail, the total time Te4 contributing to film exposure is Te4==t■/2+Δt1, and therefore 1/2 of the previous total exposure contribution time Tel.
That's all. As a result, the photographic film becomes overexposed. Therefore, in order to obtain a photographic film with the desired exposure state, the operator resets the photographing time to a shorter value and performs photographing again.

(Problem to be Solved by the Invention) As mentioned above, since the application time to the primary side of the high voltage transformer is set, the operator can adjust the exposure time and tube voltage so that the photographic film is in the desired exposure state. There is a problem in that even if the tube current is set, the film may not be photographed in the desired exposure state.

The above-mentioned problem becomes particularly serious when a moving body part is imaged, such as in chest radiography or cardiac radiography. In other words, since short-time photography is performed with a high voltage in order to prevent the effects of motion blur, the ratio of the film exposure contribution time Δt of the wave tail to the entire film exposure time increases, making it easier to achieve the desired film exposure state. Setting is difficult.

Furthermore, there is a problem in that when a photographic film with a desired exposure state cannot be obtained, photographing must be repeated, increasing unnecessary exposure of the subject to X-rays.

Therefore, the present invention has been made in view of the above circumstances, and
It is an object of the present invention to provide an X-ray control device that can easily obtain photographic film in a desired exposure state.

[Structure of the Invention] (Means for Solving the Problem) In order to achieve the above object, the present invention includes a photographing time, a tube voltage, and a tube current set so that the photographic film is in a desired exposure state. In an X-ray control device that controls voltage applied to the primary side of a high voltage transformer based on imaging condition information, the voltage applied to the primary side of the high voltage transformer is controlled based on input time limit information. a time limit means for setting a time limit; and a time limit control for inputting time limit information obtained by calculating a compensation time based on the photographing condition information and adding or subtracting the compensation time to the set photographing time to the time limit means so that the film exposure state becomes constant. It is characterized by having a means. Also,
Preferably, the compensation time is based on the film exposure contribution time at the tail of the high voltage waveform output from the secondary side of the high voltage transformer.

(for production) The operation of the apparatus having the above configuration will be explained below.

The operator sets photographing conditions, including photographing time, tube voltage, and tube current, for this apparatus so that the photographic film is exposed in a desired state. Then, the time limit control means determines a compensation time based on the set photographing condition information so that the film exposure state becomes constant. Subsequently, the obtained compensation time is added to or subtracted from the previously set photographing time, and the time is input into the time limit means as time limit information. Then, the time limit means limits the time of voltage applied to the primary side of the high voltage transformer based on the input time limit information. Therefore, the high voltage output from the secondary side of the high voltage transformer is controlled as described above, and the photographic film can be obtained in the exposure state desired by the operator.

In addition, if the wave tail in the high voltage waveform output from the secondary side of the high voltage transformer is relatively large, this wave tail has a large influence on film exposure, so the film exposure contribution time of the wave tail is It is a good idea to determine the compensation time based on this.

(Example) Examples of the present invention will be described in detail below.

FIG. 1 is a block diagram showing an apparatus 1 according to an embodiment of the present invention and an example of its application to an X-ray system.

This device 1 applies voltage to the primary side 4a of a high voltage transformer 4 in a high voltage generator 3 based on imaging condition information including imaging time information set by an operator operating a setting device 2. It controls the voltage, and the high voltage output from the secondary side 4b of this high voltage transformer 4 is connected to the high voltage cable 5 (5 a +
5 b, 5 c...) to the photographing platform U (Ua
, Ub, Uc...) arranged in the X-ray tube 6 (6a,
6b, 6c...). Then, the film FL (F
La, FLb, FLc-) are irradiated with X-rays so that the film FL is exposed.

This apparatus 1 includes an interface circuit 7 connected to the setting device 2, and a setting device 2 that determines a compensation time so that the exposure state of the film FL is constant based on the photographing condition information.
a time limit control means 8 that inputs time limit information obtained by adding and subtracting from the imaging time set by the above into a time limit means to be described later; and a tube voltage control circuit 9 that controls the imaging tube voltage based on the input tube voltage control signal. , a tube current control circuit 10 that controls the photography tube current based on the input tube current control signal, and a tube current control circuit 10 that limits the voltage time applied to the primary side 4a of the high voltage transformer 4 based on the input time limit information. an internal setting device SW that sets internal setting information that can be set in advance and contributes to film exposure other than the external setting information set by the setting device 2; Internal interface connected to internal setting device SW5? 12.

The setting device 2 includes a setting device SW■ for selecting the imaging platform U and the X-ray tube 6, a tube voltage setting device SW2 for setting the imaging tube voltage, and a tube current setting device SW3 for setting the imaging tube current. , and a photographing timer setting device SW4 for setting the photographing time. The external setting information from this setting device 2 is
This external setting information is input to the interface circuit 7, and is further transmitted to the CPU 13 via the data path DB based on the address signal from the CPU 13 via the address bus AB.
It is now being incorporated into the In Fig. 1, each imaging platform U (Ua, Ub, Uc...) has one X-ray tube 6 (
6a, 6b, 6c...), but one imaging platform U may be equipped with a plurality of X-ray tubes 6, and in this case, the setting device SW1 The platform U and one of the plurality of X-ray tubes 6 provided on the imaging platform U can be specified.

The time limit control means 8 is a CPU that controls each part of the device 1.
13, and a memory for storing a program such as an execution procedure for realizing the present invention, that is, a program for executing film photography that can keep the film exposure state constant based on set photography condition information, compensation time data, etc. The device 14 has a latch circuit 15 connected to the CPU 3 by a data path DB and an address bus AD. The storage device 14 is configured to store various data for determining the film exposure contribution time at the wave tail of the high voltage waveform output from the secondary side 4a of the high voltage transformer 4 as compensation time by the CPU 13. ing. The latch circuit 15 latches the control data of the tube voltage, tube current, and imaging time output by the CPU 13, and is configured to latch the tube voltage control circuit 9, tube current control circuit 10, and imaging timer control circuit 1, respectively.
1 to output a control signal.

The internal setting information from the internal setting device SW5 is input to the internal interface circuit 12, and further this setting information is
Based on the address signal from the CPU 13 via the address bus AB, the data is taken in to the CPU 3 via the data path DB, and then stored in the storage device 14 via the data path DB. The internal setting information by the internal setting device SW, corresponds to the external setting information of the imaging platform U and the X-ray tube 6 set by the setting device SW0, and the X on the imaging platform U that contributes to the exposure state of the film FL. This information includes the linear attenuation rate, internal impedance of the X-ray tube 6, high-voltage cable length, sensitivity of the film FL used, etc. The above-mentioned internal setting information is normally set at the time of installation according to the installation conditions of the X-ray imaging system.

The CPU 13 searches the compensation time data of the shooting time stored in the storage device 14 based on the external setting information set by the setting device 2 and the internal setting information set by the internal setting device SW, and sets the time limit. The compensated photographing time data as information is sent to the latch circuit 15. Under the control of the CPU 13, the latch circuit 15 sends a photographing time control signal to the photographing timer control circuit 11, which can make the film exposure contribution time constant in the high voltage output waveform of the secondary side 4a of the high voltage transformer 4. I try to do that.

The operation of the embodiment device 1 having the above configuration will be explained with reference to FIGS. 2 and 3.

The operator selects the imaging platform Ua and the X-ray tube 6a, and adjusts the imaging time (
tto). Photographing condition data including tube voltage (Ve.) and tube current (AIO) are input to each setting device SW1 to SW of setting device 2.
Operate step 4 to set. Also, a case will be described in which a person who has become fat is first imaged, and then a person whose body thickness requires only half the amount of X-rays compared to the person who has become fat is imaged.

The setting information from the setting device 2 is sent to the interface circuit 7.
On the other hand, the CPU 13 reads out the program stored in the storage device 14 and executes the contents of the program. First, the circuits 7 and 12 into which the setting information has been input are designated in order, and an operation for reading information from these circuits 7 and 12 is performed.

That is, when the interface circuit 7 is specified, external setting information (imaging stage Ua, X-ray tube 6a, tube voltage V1o,
Tube current AI'0 and imaging time t10) are read into the CPU 13. When the internal interface circuit 12 is specified, the previously set internal setting information is read into the CPUI 3.

Next, when the CPU 13 reads the above information, it first holds each piece of information, and then sends the tube voltage data (Ve.) and tube current data (Ae.), excluding the imaging time data (11.), to the latch circuit 15. input.

Next, the CPU 13 accesses the storage device 14 based on the external setting information set in the setting device 2, and uses the internal setting device SW.
, searches for and retains the internal setting information set in .

Further, the CPU 13 accesses the storage device 14 again based on the internal setting information, searches for and holds the compensation time data for the photographing time programmed in advance, and adds this compensation time data to the photographing time that is subsequently read. That is, the CPU 13 adds a compensation time Δtc. to the set photographing time tlO. and total exposure contribution shooting time t's
1. seek.

The CPU 13 calculates the photographing time ts1 after this compensation. data is output to the latch circuit 15.

The latch circuit 15 receives the tube voltage data (VI
O) , a tube voltage control signal based on the compensated imaging time data (tsio) together with the tube current data (AIO);
A tube current control signal and an imaging time control signal are outputted to a tube voltage control circuit 9, a tube current control circuit 10, and an imaging timer control circuit 1, respectively.

The high voltage generator 3 generates an exposure contribution time Te1 from the secondary side 4b of the high voltage transformer 4 based on the control of each tube voltage control circuit 9, tube current control circuit 10, and photographing timer control circuit 11.
A high voltage of 0 is applied to the X-ray tube 6a, and a set high current is caused to flow. X-rays are emitted toward the human body from the X-ray tube 6a, and the X-rays that have passed through the human body are incident on the film FLa, so that the film FLa becomes a photographic film in an exposure state desired by the operator.

Next, a person whose body thickness requires half the amount of X-rays compared to the person photographed last time is photographed. The operator sets the set shooting time t20 as shown in FIG. 3(a) in order to obtain a photographic film with an exposure state similar to that of the film obtained in the previous photograph. The set shooting time t■ shown in FIG. 2(a). half of t■. Select /2 and take a picture.

In the same way as described above, the operator uses the setting device 2 to set the photographing platform U.
a. Select the X-ray tube 6a, and set the tube voltage ■■0 and tube current A0, which are the same settings as last time. Enter.

From here on, it works in the same way as the previous shooting. In other words, setting device 2
External setting information (imaging table Ua, X-ray tube 6a, tube voltage v1o, tube current Ae..imaging time t20) from the CPU
13. Next, when the CPU 13 reads the above information, it holds each piece of information, and furthermore, the photographing time data (t
The tube voltage data (V1O) and tube current data (AIO) except for 20) are input to the latch circuit 15. Furthermore, CPU
Reference numeral 13 accesses the storage device 14 based on the external setting information and internal setting information in the same way as the previous time, and obtains compensation time data (tC2) for the photographing time programmed in advance.
) is searched and held, then this compensation time data (t C2 ) is subtracted from the read imaging time t20. That is, by subtracting the compensation time tC2 from the set shooting time t20, the total exposure contribution shooting time ts1o obtained previously is 1/2.
The total exposure contribution photography time ts2o corresponding to is calculated. C
PUI 3 is the data of the shooting time after this compensation (t
S20) is output to the latch circuit 15. Latch circuit 1
5 is a tube voltage control signal, a tube current control signal, and an imaging time control based on the compensated imaging time data (tS20) along with the previously outputted tube voltage data (V1o) and tube current data (AIO). The signals are output to a tube voltage control circuit 9, a tube current control circuit 10, and a photographing timer control circuit 11, respectively.

The high voltage generator 3 generates an exposure contribution time Te2 from the secondary side 4b of the high voltage transformer 4 based on the control of each tube voltage control circuit 9, tube current control circuit 10, and photographing timer control circuit 11.
A high voltage of 0 is applied to the X-ray tube 6a, and a set high current is caused to flow. The X-ray tube 6a emits X-rays toward the human body, and the X-rays that have passed through the human body are incident on the film FLa, which becomes a photographic film in the same exposure state as the previous exposure.

According to the apparatus of this embodiment, as described above, when the wave tail in the high voltage waveform output from the secondary side of the high voltage transformer is relatively large, the wave tail is calculated based on the film exposure contribution time at the wave tail. Since the compensation time is determined, the exposure state of the photographic film can be set as desired by the operator.

Further, unnecessary X-ray exposure to the subject can be reduced.

Although one embodiment has been described above, the present invention is not limited to this, and various modifications can be made without changing the gist thereof.

For example, in order to make the exposure state of the film the same for the first and subsequent shots, we have explained the case where control is performed using the shooting time set by the operator. A similar effect can be obtained by changing the current. Further, although the compensation time data is stored in advance in accordance with various conditions, it may be determined by calculation.

[Effects of the Invention] According to the present invention described in detail above, the time limit information obtained by adding or subtracting the compensation time to the shooting time set by the time limit control means so that the film exposure state becomes constant is input to the time limit means. Since the voltage applied to the primary side of the high voltage transformer is timed based on the time limit information inputted by the time limit means, it is possible to easily obtain the photographic film in the desired exposure state. A control device can be provided.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention and its application to an X-ray imaging system, and FIGS. 2(a) to (C)
) and Figures 3(a) to (c) are high voltage output waveform diagrams of the device shown in Figure 1, Figures 4(a), (b), and Figure 5(a).
(C) and FIG. 6(a). (b) is a high voltage output waveform diagram of a conventional device. 1... X-ray control device, 4... High voltage transformer, 4a
...Primary side of high voltage transformer, 8. Time limit control means, 11. Photographing timer control circuit (time limit means), A. ...Tube current, ? L (FLa, FLb, FLc-)-film, t. +t20...Set shooting time, tc■, tc2
... Compensation time, tS10+jS2 (1... Shooting time after compensation (time limit information), ■... Tube voltage, wb... Wave tail. Fig. 3 Fig. 6

Claims (2)

[Claims] (1) X-rays that control the voltage applied to the primary side of the high-voltage transformer based on imaging condition information including imaging time, tube voltage, and tube current set so that the imaging film is in the desired exposure state. In the control device, a time limit means for limiting the voltage applied to the primary side of the high voltage transformer based on the input time limit information, and compensation so that the film exposure state is constant based on the photographing condition information. An X-ray control device characterized by comprising: time limit control means for inputting time limit information obtained by calculating a time and adding or subtracting it from the set imaging time to the time limit means. (2) The X-ray control device according to claim 1, wherein the compensation time is based on the film exposure contribution time at the wave tail of the high voltage waveform output from the secondary side of the high voltage transformer.