JPH0358731B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an X-ray diagnostic apparatus, and more particularly to an X-ray diagnostic apparatus having a function of always optimizing the brightness of a monitor image despite changes in various diagnostic conditions. .

Most X-ray diagnostic equipment performs X-ray fluoroscopy and X-ray photography for the purpose of diagnosing the dynamics of subjects such as patients and positioning them for imaging. Examples include those shown in Figure 1. The X-ray controller 1 controls the high-voltage generator 2 to emit X-rays from the X-ray tube 3, and at this time, the X-rays passing through the subject 6 placed on the top plate 5 are After converting it into an optical image by an X-ray-light image conversion device, such as an image intensifier (hereinafter abbreviated as I.I.) 9, the image is captured by a television camera 14 via an optical system 10,
The image is displayed on a display device, for example, a TV monitor 15, for fluoroscopy, and when direct photography is performed, the X-ray film 8 of the spotting device 7 is inserted, and when indirect photography is performed, it is focused with the objective lens 12A. A half mirror 16 is placed in the middle of the optical lens 12B to let in a part of the light, and an indirect camera 17 is used to take pictures.
In addition, in the figure, 4 is an X-ray diaphragm, 11 is a lens diaphragm, and 1
3 is an image pickup tube.

Generally, the fluoroscopy condition is the X-ray tube voltage, for example 50~
120KV, X-ray tube current for example 0-4mA, time is continuous. On the other hand, the X-ray tube voltage under direct imaging conditions is approximately the same as that for fluoroscopy, e.g. 70 to 120 KV,
The tube current is, for example, 100 to 300 mA, about 100 times that during fluoroscopy, and the imaging time is 0.01 to 0.1 seconds. Therefore, the incident X-ray dose per unit time to I/I is much higher during imaging than during fluoroscopy. If short-term shooting is required, the cost will be higher.
Even when taking into account the X-ray absorption of the close-contact device made up of an intensifying screen and film that is inserted between the subject 6 and I/I 9 only during imaging, simple calculations show that it is extremely high compared to the case of fluoroscopy. This extreme difference in the amount of radiation incident on I and I9 directly appears as a difference in the amount of light incident on the television camera.

Generally, in X-ray fluoroscopy, the aperture diameter of the lens diaphragm 11 that controls the amount of light input to the X-ray television camera is set in advance to be an appropriate amount during fluoroscopy because the X-ray television monitor is continuously viewed directly. Therefore, while a conventional device equipped with a lens aperture whose aperture diameter cannot be varied displays a clear X-ray image on the television monitor 15 during fluoroscopy, an extremely high level video signal is output at the moment of imaging. X on TV monitor 15
Line images cause halation, resulting in the following drawbacks.

(1) An extremely excessive amount of light enters the television camera, leading to deterioration of the characteristics and shortening of the service life of the television camera.

(2) Momentary halation occurs when the image is viewed on a TV monitor with appropriate brightness during fluoroscopy, causing physical and psychological adverse effects on the observer such as eye fatigue.

(3) Halation that occurs at the moment of imaging makes it difficult to recognize the position and situation of the contrast agent on the monitor image at the time of imaging.

(4) If an excessive amount of light is incident, the output signal will not fall immediately and will remain as an afterimage for a long time even if the input light amount stops due to the fall characteristics of the television camera. Therefore, even if the conditions are returned to fluoroscopic conditions immediately after imaging, a clear fluoroscopic image cannot be obtained due to the afterimage.

Indirect photography also requires a larger dose of X-rays than fluoroscopy, causing similar problems. In addition, dual mode I/I (DUAL MODE I/I), triple mode I/I (TRIPLE MODE I/I)
In the case of X-ray diagnostic equipment with multiple input field of view switching I/I such as I), the output brightness for the X-ray incident dose differs depending on each setting field of view mode, so the above-mentioned fluoroscopy, direct imaging, and indirect imaging conditions are different. The output brightness can be further varied depending on the combination.

In this case, the lens diaphragm using a conventional mechanical mask, or the conventionally known lens diaphragm
Although the lens diaphragm proposed in No. 14421 can be controlled to an arbitrary value, it is not possible to appropriately control the amount of light incident on the diversified television cameras with a lens diaphragm system that allows only one aperture value to be set.

The present invention has been made to solve the above-mentioned problems, and provides an X-ray diagnostic device equipped with an optical diaphragm function that can automatically set the amount of light incident on a television camera appropriately according to the purpose of use. The purpose is to

An embodiment of the present invention will be described below with reference to FIGS. 2 and 3. FIG. 2 is a block diagram showing the configuration of the apparatus according to the present invention. In the figure, the same parts as in FIG. For this purpose, a lens diaphragm drive circuit 19 that controls the diameter of the lens diaphragm 11, which is a light amount adjustment means arranged in front of the condensing lens 12B in the optical meter 10, and a lens diaphragm (light amount adjustment means) that controls this drive circuit 19 are provided. control circuit) A control circuit 18 is provided, and this control circuit 18
It is controlled by a signal S _M based on mode selection from the line controller 1 and an I/I input visual field selection signal S _I.

Next, the specific configurations of the lens diaphragm control circuit 18 and the lens diaphragm drive circuit 19 will be explained.

FIG. 3 is a detailed circuit diagram of the lens aperture control circuit 18 and the lens aperture drive circuit 19. This lens aperture control circuit 18 includes a control signal generating section 18A,
It is composed of an initial setting section 18B and a multiplication section 18C. First, the control signal generator 18A
Various mode signals from the X-ray controller 1, namely, a fluoroscopy mode signal S _M0 , a direct imaging mode signal S _M1 , an indirect imaging mode signal S _M2 , and an I/I input visual field selection signal,
That is, the first input visual field selection signal S _I1 , the second input visual field selection signal S _I2 , and the third input visual field selection signal S _I3 are input. Of these, the first input visual field selection signal S _I1 and the perspective mode signal S _M0 are not actively used. That is, the second and third input visual field selection signals S _I2 and S _I3 , the direct photography mode signal S _M1 , and the indirect photography mode signal S _M2 are sent to the correspondingly arranged first to fourth inverters IN ₁ to IN ₄ , respectively. Input,
Outputs of the first and second inverters IN ₁ and IN ₂ are connected to the first and second NAND gates NAND ₁ ,
applied to one input of each of NAND ₂ , and the third
and the outputs of the fourth inverters IN ₃ and IN ₄ are applied as two inputs to a third NAND gate NAND ₃ , and a signal obtained by inverting the output of this NAND gate NAND ₃ and the direct shooting mode signal S _M1 is set as the two inputs. An OR gate OR ₁ is provided, and the output of this OR gate OR ₁ is connected to the first and second NAND gates NAND ₁ ,
A fourth NAND gate NAND ₄ is provided, which is commonly applied to NAND ₂ and the other input, and which has two inputs of the outputs of the first and second NAND gates NAND ₁ and NAND ₂ , and the output of the OR gate OR ₁ is connected to the fifth gate. is inverted by the inverter IN ₅ to obtain a first control signal S ₁ , a second control signal S ₂ is obtained from the third inverter IN ₃ , and the output of the third NAND gate NAND ₃ is inverted by the sixth inverter IN 3 . Invert the third control signal at IN ₆
Obtain S ₃ and convert the fourth NAND gate NAND ₄ to the seventh
The fourth control signal S ₄ is inverted by the inverter IN ₇ of
obtained, the first and second NAND gates NAND ₁ ,
NAND ₂ to the 8th and 9th inverter IN ₈ ,
It is inverted at IN ₉ to obtain fifth and sixth control signals S ₅ and S ₆ .

The initial setting section 18B is an operational amplifier (hereinafter also referred to as an operational amplifier) which inputs the divided voltage outputs of the voltage dividing resistors R ₁ and R ₂ to an inverting input terminal via a resistor R ₃ and whose non-inverting input terminal is grounded. A ₁ and a variable resistor VR ₁ to VR ₃ between the input and output terminals of this operational amplifier A ₁
and analog switches AS ₁ to _{AS 3} are connected in parallel for each corresponding code, and three series circuits are connected in parallel. Each of the analog switches AS ₁ to _{AS 3} is made of, for example, an FET, and each of the analog switches AS 1 to AS 3 is configured to receive the first to third signals from the control signal generating section 18A.
It is designed to be controlled by control signals S ₁ to S ₃ . Here, the variable resistors VR ₁ to VR ₃ are set to have different values in sequence.

The multiplication section 18C has an operational amplifier _A2 which inputs the output of the operational amplifier _A1 of the initial setting section 18B to an inverting input terminal via a resistor _R4 , and whose non-inverting input terminal _is grounded. A variable resistor VR ₄ to _{VR 6} and an analog switch are connected between the input and output terminals of
Three series circuits in which AS ₄ to AS ₆ are combined for each corresponding code and connected in series are connected in parallel. Each of the analog switches AS ₄ to _{AS 6} is composed of, for example, a FET, and the control signal generator 18
It is designed to be controlled by control signals S ₄ to S ₆ from A. Here, the variable resistors VR ₄ to VR ₆ are set to have different values in sequence.

When in the fluoroscopy mode, the fluoroscopy mode selection signal S _M0 is generated, but since this signal is not actively used, only the first control signal S ₁ is output from the control signal generator 18A, and the initial Setting section 18
The first analog switch in the series circuit connected between the input and output terminals of operational amplifier _A1 in B
AS ₁ will be closed, variable resistor VR ₁ and resistor R ₃
The calculation result output with the amplification factor determined by is output and input to the multiplier 18C. Below, during direct shooting, the direct shooting mode signal S _M1 is input and the second control signal S ₂ is generated, so only the analog switch AS ₂ is closed and the calculation result is output with an amplification factor based on it, and during indirect shooting A third control signal _S3 is output and the third analog switch
Only AS ₃ is closed, and a calculation result output with an amplification factor based on it is obtained. Then, in the multiplication section, when the first input field of view of I and I is selected, the first input field of view selection signal _S1 is output, but this signal is not actively used, and the control signal generation section 18
Only the fourth control signal _S4 is output from A. This causes the analog switch AS ₄ to be connected between the input and output terminals of the operational amplifier A ₂ in the multiplier 18C.
Only the fourth analog switch AS ₄ of AS ₆ is closed, and the output from the initial setting section 18B and the variable resistance when the analog switch AS ₄ is closed are
It is multiplied by the amplification factor determined by VR ₄ , and the multiplication result is output. Similarly, when the second I/I input visual field is selected, an input visual field selection signal SI ₂ is output,
Based on this, a fifth control signal _S5 is generated, and only the fifth analog switch _AS5 in the multiplier 18C is closed to perform the same multiplication as described above, and furthermore, the third I/I input field of view is selected. when the corresponding signal SI ₃ is applied, a sixth control signal S ₆ is generated,
The sixth analog switch AS ₆ is closed and a multiplication similar to that described above is performed.

The lens aperture drive circuit 19 includes an error amplifier 19A that receives the output from the lens aperture control circuit 18 as one input, a drive circuit 19B that generates a drive signal based on the output of the amplifier 19A, and this drive circuit 19B. a galvanometer 19C that is driven by the aperture to control the aperture diameter of the lens aperture, an aperture diameter detector 19D that detects the amount of rotation of the rotor MO of the galvanometer, and an amplifier 19E that amplifies the output of the aperture diameter detector 19D. The output of this amplifier 19E is applied to the other input terminal of the error amplifier 19A. Therefore, the aperture diameter setting signal inputted by the error amplifier 19A and the actually set aperture diameter detection signal (amplifier 19E)
The aperture diameter is compared with the aperture diameter (output of the aperture diameter), and the aperture meter 19C is driven until the two match, thereby automatically adjusting the aperture diameter to the optimum aperture diameter.

Next, the operation of the apparatus having the above configuration will be explained.

First, considering the case of fluoroscopy, X-rays emitted from the X-ray tube 3 pass through the X-ray diaphragm 4, the top plate 5, and the object 6, and enter the I/I9. At I/I9, the incident X
It first converts a line into an electron, then converts the electron into light and outputs it. The internal force light of I.I9 is guided to the imaging tube 13 by the objective lens 12A and the condensing lens 12B. A video signal from the imaging tube 13 is sent to a television monitor 15 and displayed as an X-ray fluoroscopic image. At this time, the X-ray controller 1 sends the fluoroscopy mode signal S _M0
However, in the lens diaphragm control circuit 18 shown in FIG. 3, since both the direct and indirect photography mode signals S _M1 and S _M2 are at the "H" level, the output of the fifth inverter IN ₅ , In other words, since only the first control signal S ₁ becomes "H" level and only the first analog switch AS ₁ closes, the input voltage from the operational amplifier A ₁ is multiplied by the voltage across the terminals of the first variable resistor VR ₁ . generated output. At this time, if the first input field of view is selected among the input fields of view of the I/I9, only the first input field of view selection signal SI ₁ is output, so that the control signal generator 18A outputs the fourth input field of view.
control signal _S4 is output, the fourth analog switch _AS4 in the multiplier 18C is selected, and the variable resistor _VR4 is selected.
The output signal from the initial setting section 18B is multiplied by an amplification factor determined by the input resistance R4 and the input resistance _R4 , and the resultant signal is output. Thereafter, when the second and third input visual fields are selected in the same manner, respective selection signals SI ₂ and SI ₃ are output, and the fifth,
The sixth control signals S ₅ and S ₆ are output, respectively, and the respective analog switches AS ₅ and AS ₆ are selected, and the output signal multiplied by the amplification factor at that time is output from the multiplier 18C. That will happen.
The lens diaphragm drive circuit 19 sets the aperture diameter of the lens diaphragm to be appropriate based on the output signal from the lens diaphragm control circuit 18. That is,
A signal that detects the current aperture diameter (aperture diameter detector 19
The error amplifier 19A compares the amplified signal (output of the amplifier 19E) of the output of the amplifier _A2 with the output signal from the operational amplifier A2, and applies an output corresponding to the difference between the two to the drive circuit 19B. When the galvanometer 19C is activated by the output of the drive circuit 19B,
and rotate the rotor MO to adjust the diameter of the lens aperture. The aperture diameter at this time is the detector 19D.
The detected output is input to the error amplifier 19A via the amplifier 19E and is used for comparison. This operation is repeated and the error amplifier 1
When the output of 9A becomes zero, the lens aperture is set to the appropriate aperture diameter.

Next, the operation in shooting mode will be explained. In this case, the X-ray film 8, which has been waiting in a position not affected by X-rays during fluoroscopy, moves into the X-ray flux and is exposed to X-rays for direct imaging, and the optical system 10
Both indirect photography, in which photography is performed with an indirect camera through a half mirror 16 placed inside the camera, are conceivable. And for direct shooting, a third inverter
IN ₃ input is "L" level, 4th inverter
Since the input of IN ₄ becomes "H" level, the second control signal S ₂ is output in the lens aperture control circuit 18 of FIG.
occurs, only the second analog switch AS ₂ closes, and the variable resistor VR ₂ is selected. In addition, in the case of indirect photography, the input of the third inverter IN ₃ is at "H" level and the input of the fourth inverter IN ₄ is at "L" level, so a third control signal S ₃ is generated. Only analog switch AS ₃ is closed and variable resistor VR ₃ is selected. The amplification degree of the operational amplifier _A1 is determined by the variable resistors _VR2 and _VR3 selected according to each shooting mode, and the output of the operational amplifier _A1 obtained in this way is transmitted to the following through the resistor _R4 . It is input to the operational amplifier _A2 of the stage. As mentioned above, this operational amplifier _A2 performs correction based on the selection of the I/I input field of view, and the I/I input field of view can be selected in three stages.
In I, when the first input field of view is selected, the inputs of the first and second inverters IN ₁ and IN ₂ are both at "H" level, so only the analog switch AS ₄ in the operational amplifier A ₂ is closed, and the variable resistor is closed.
This means that VR ₄ has been selected. Similarly, when the I/I input field of view is the second input field of view, the input of inverter IN ₁ is at "L" level and the input of inverter IN ₂ is at "H" level, so only analog switch AS ₅ is turned on and variable resistor VR ₅ is turned on. is selected and the I/I input field of view is the third input field of view, the input of inverter IN ₁ is at "H" level and the input of inverter IN ₂ is at "L" level.
Since it is at level, only analog switch AS ₆ is turned on and variable resistor VR ₆ is selected. The amplification factor of the operational amplifier A ₂ is determined by VR ₄ , VR ₅ or VR ₆ selected by each input field of view, and the operational amplifier
The output of A ₁ is multiplied by the amplification factor by operational amplifier A ₂ and outputted, and is input to the lens diaphragm drive circuit 19 in the same manner as described above, where automatic control is performed to obtain an appropriate aperture diameter. In this way, the correct amount of light is always input to the image pickup tube (TV camera), and therefore the TV
The brightness of the monitor is also maintained at an appropriate level.

Although there is no particular limitation in the above operation, the amount of light incident on the image pickup tube in the photographing mode increases significantly compared to the case in the fluoroscopy mode, so in order to reduce this, the diameter of the lens aperture is significantly increased. Furthermore, since the amount of incident light changes between direct photography and indirect photography even when the shooting is the same, the diameter of the lens diaphragm is controlled to change accordingly. It is assumed that the values of the variable resistors VR ₁ to _{VR 3} that set the amplification factor of the operational amplifier A ₁ are set so that such control is possible. Similarly, for the I/I field of view, which changes in three stages, the amount of input light changes depending on the change in the _field of view. It goes without saying that the values of the variable resistors VR ₄ to VR ₆ of operational amplifier A ₂ are set so that the aperture diameter is such that

The present invention is not limited to the embodiments described above, and various modifications are possible. For example, in the above embodiment, the parameters for adjusting the aperture diameter of the lens aperture are I and I.
Although we considered the case where the input fields of view of the I and I are different, there is no need to take this into account if the input fields of view of the I and I are constant. Control signals used in the route also become unnecessary. In addition, a galvanometer and rotor were used to drive the lens aperture, but
This is to speed up the opening/closing operation of the diaphragm and to make it smaller, but it is not necessarily limited to this as long as it achieves the same function and purpose.

According to the present invention described in detail above, the amount of light input to the image pickup tube is automatically set to be always appropriate under all diagnostic conditions (particularly fluoroscopy mode and imaging mode), and as a result, the brightness on the television monitor is now appropriate, and all of the drawbacks of the prior art mentioned above are eliminated.

[Brief explanation of drawings]

Fig. 1 is a system block diagram showing an example of a conventional device, Fig. 2 is a system block diagram showing an embodiment of the present invention, and Fig. 3 is a system block diagram showing an embodiment of the present invention. FIG. 2 is a circuit diagram showing an example of a specific configuration. 1...X-ray controller, 2...X-ray generator, 3...
X-ray tube, 6... Subject, 7... Spot device, 8
...X-ray film, 9...X-ray-light image conversion device,
10... optical system, 11... light amount adjustment means, 13...
...Picture tube, 15...Monitor, 17...Indirect camera,
18...Light amount adjustment means control circuit, 19...Light amount adjustment means drive circuit.

Claims (1)

[Claims] 1. An X-ray controller that controls the X-ray intensity of emitted X-rays from an X-ray tube by setting diagnostic conditions such as fluoroscopy or photography, and an X-ray-light image that converts the X-rays that have passed through the subject into a light image. It has a conversion device, an optical system that guides the optical image from the X-ray-light image conversion device to a television camera, and a display device that displays an X-ray fluoroscopic image based on the output from the television camera. An X-ray diagnostic apparatus that monitors an X-ray fluoroscopic image during imaging, comprising: a control signal generating section that generates a control signal corresponding to the set diagnostic conditions; a light amount adjusting means that adjusts the amount of light of the optical system; and the amount of light. By providing a light amount adjustment means control circuit that compares the current adjustment value of the adjustment means with the control signal from the control signal generator and controls the light amount adjustment means so that the two substantially match.
An X-ray diagnostic apparatus characterized in that the amount of light incident on the television camera is appropriate under various diagnostic conditions.