JPH07336597A - Fluoroscopic and radiographic device - Google Patents

Abstract

PURPOSE:To control fluoroscopic conditions and radiographic conditions at the time of X-raying and to obtain a stable operation through easy adjustment by using a video signal for an X-ray television camera to observe an X-ray image. CONSTITUTION:In the case of X-raying, an X-ray emitted from an X-ray tube 1 is projected onto an object 3 via a variable aperture and the X-ray is converted into a visual image by an image intensifier after transmitting through the object 3 and the visual ray is made incident onto an X-ray TV device 8. The device 8 converts the visual image into an electric signal and it is fed to a luminance signal output circuit 10. The circuit 10 extracts selectively corresponding to the center of the visual ray and gives the signal to a preamplifier 14 of an automatic exposure controller 11. The controller 11 compares the output of the amplifier 14 with an X-ray image luminance reference signal stored in advance in an EEPROM 24 on a bus line of a CPU 21 and when the luminance of the X-ray image is too high, the X-ray condition is lowered and when too low, the X-ray condition is raised and when the luminance is within a proper range, the X-ray condition is maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses an automatic exposure device to determine an X-ray condition during fluoroscopy and an X-ray condition during radiography, and at the time of fluoroscopy, an electric signal output from an X-ray television device is used for fluoroscopy. The present invention relates to an X-ray fluoroscopic imaging apparatus which maintains an appropriate X-ray condition, and determines an imaging X-ray condition suitable for an image receiving purpose from the fluoroscopic X-ray condition appropriately determined during fluoroscopy during imaging.

[0002]

2. Description of the Related Art In a conventional X-ray fluoroscopic apparatus, X-ray conditions during fluoroscopy and radiography are determined as follows. That is, during fluoroscopy, the output of a light receiving element such as a photomultiplier that receives a visible light image that is the output of the image intensifier, or the whole or part of the output video signal of the X-ray television device is converted into an electrical signal. Input to the automatic exposure control device, and the automatic exposure control device determines the intensity of the X-ray according to the output of this light receiving element or the intensity of the electric signal,
The X-ray intensity determination signal is sent to the X-ray high voltage device so that the fluoroscopic X-ray condition is kept proper. During photographing, the X-ray sensor used during fluoroscopy or the X-ray sensor provided exclusively for the photo timer during photographing detects the X-ray intensity after passing through the subject and converts it into an electrical signal. The electric signal proportional to is integrated by an integrator, and when the integrated value reaches a predetermined value, an X-ray high voltage device is instructed to end the imaging so that an appropriate amount of X-rays is irradiated onto the subject. There is.

[0003]

When X-ray fluoroscopy is performed, when the situation of the subject is different between the fluoroscopy and the radiography, or there is a difference in the X-ray irradiation field, the fluoroscopy is performed. An error may occur between the determined X-ray condition and the appropriate X-ray condition at the time of imaging. Further, depending on the accuracy of the X-ray high voltage apparatus, the tube voltage and tube current (m
Such errors also occur due to the fact that A), the photographing time (s), etc. cannot be continuously set. In the above-mentioned conventional X-ray fluoroscopic imaging apparatus, since the X-ray condition at the time of fluoroscopy and the X-ray condition at the time of imaging are set separately, there is an advantage that such an error can be corrected. .

On the other hand, on the other hand, even if an appropriate X-ray condition can be set by utilizing a diaphragm or the like for observing a subject during fluoroscopy, the operation of the photo timer becomes unstable during photographing. However, there is a problem that the X-ray condition at the time of photographing may not be set appropriately. This problem occurs because the X-ray irradiation field is normally expanded to the film size during photographing, and the X-ray sensor is affected by direct rays from the side surface of the subject that did not affect the X-ray sensor during fluoroscopy. Further, when there is a difference in the X-ray energy dependence characteristic between the X-ray sensor and an image receiver such as a film for recording a captured image, and the amount and quality of X-rays incident on the image receiver such as a film, X-ray incident on the X-ray sensor When the amount and quality of X-rays incident on the X-ray sensor are different, the operating point of the phototimer deviates from the appropriate value, and an appropriate film density cannot be obtained. is there.

Further, since the X-ray controller attempts to correct these problems, the adjustment takes time, the circuit configuration of the controller becomes complicated, and the cost of the entire X-ray fluoroscopic apparatus increases. There is also the problem of being lost.

An object of the present invention is to solve the above-mentioned problems of the prior art, have a simple circuit configuration, are easy to adjust, and are equipped with an automatic exposure control apparatus that operates stably. It is to provide the device at low cost.

[0007]

The above objects are to provide an X-ray tube device for generating X-rays, a video recording means for recording an X-ray image after passing through an object, and an optical intensity distribution of the X-rays passing through the object. An image intensifier for converting into an image, an X-ray television device for converting this optical image into an electric signal, a high voltage generator for generating a high voltage applied to the X-ray tube device, and an X-ray tube device. In an X-ray fluoroscopic imaging apparatus including an X-ray control device that determines the X-ray condition to be controlled and an automatic exposure control device that adjusts the X-ray dose applied to a subject, the device is connected to a CPU that controls the operation of the automatic exposure control device. In memory,
A correspondence table for determining the X-ray tube voltage at the time of imaging from the X-ray tube voltage at the time of fluoroscopy and the tube current time product as a function of the X-ray tube voltage at the time of imaging are stored, and the image All or part of the output of the tensiger is input to the automatic exposure control device via the X-ray television device, and the fluoroscopy X-ray is transmitted in the automatic exposure control device according to the intensity of the output electric signal of the X-ray television device. The X-ray tube voltage is determined, and at the time of shooting, the X-ray tube voltage corresponding to the fluoroscopic X-ray tube voltage is determined based on the correspondence table stored in the memory. Means are provided for determining the value of the tube current time product corresponding to the tube voltage by performing an interpolation calculation based on the value of the tube current time product as a function of the X-ray tube voltage at the time of imaging stored in the memory. It is achieved by

[0008]

According to the X-ray fluoroscopic imaging apparatus of the present invention, during fluoroscopy, the output video signal of the X-ray television apparatus is converted into an electric signal and input to the automatic exposure control apparatus. By transmitting the X-ray intensity determination signal to the X-ray high voltage device so as to keep the intensity of the electric signal constant, it is possible to perform fluoroscopy under appropriate fluoroscopic X-ray conditions according to the situation of the subject. Further, at the time of photographing, the X-ray condition at the time of photographing is determined by indirectly detecting the thickness of the subject from the fluoroscopic X-ray condition thus determined at the time of fluoroscopy. That is, a correspondence table for determining a tube voltage at the time of photographing from a tube voltage at the time of fluoroscopic observation, and a tube current time as a function of the tube voltage at the time of photographing are stored in a memory connected to a CPU for controlling the operation of the automatic exposure control device. The value of the product is stored in advance, and the CPU determines the photographing tube voltage at the time of photographing from the fluoroscopic tube voltage decided at the time of photographing, based on this correspondence table at the time of photographing, and the photographing tube thus decided. An interpolating calculation is performed between the voltage and the value of the tube current time product as a function of the tube voltage at the time of shooting, which is stored in the memory, and the value of the tube current time product corresponding to the determined shooting tube voltage is determined. . In the automatic exposure control device of the X-ray fluoroscopic imaging apparatus of the present invention, the value of the imaging tube voltage and the tube current time product is thus determined, and the X-ray intensity determination signal is output to the X-ray control apparatus for the purpose of image reception. Try to get the exact X-ray dose.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the X-ray fluoroscopic imaging apparatus of the present invention will be described below with reference to FIGS.

FIG. 1 is a block diagram showing the overall construction of an X-ray fluoroscopic apparatus according to the present invention. As shown in FIG. 1, the X-ray fluoroscopic imaging apparatus of the present invention includes an X-ray tube device 1 for generating X-rays, a movable diaphragm 2, a table 4 on which an object 3 is placed, an X-ray image receiving film 5, and this film 5. A film holder 6 for holding, an image intensifier 7 for converting X-rays transmitted through the subject 3 into a visible light image, an X-ray television device 8 for converting an output of the image intensifier 7 into an electric signal, a distributor 9, Luminance signal output circuit 10,
An automatic exposure controller 11, an X-ray controller 12, and an X-ray high voltage generator 13 are provided. The automatic exposure control device 11
Preamplifier 14, F-kV (fluoroscope voltage) setting circuit 1
5, R-kV (shooting tube voltage) setting circuit 16, R-Tim
e (imaging time) setting circuit 17 and the X-ray controller 1
2 includes a kV (tube voltage) adjusting mechanism 18 and a switch means 19.

FIG. 2 is a diagram showing the structure of a control mechanism for controlling the operation of the automatic exposure control device 11. In this embodiment, the automatic exposure control device 11 and the X-ray control device 12 are combined into one unit.
It is controlled by two CPUs 21. CPU21
In the bus line of, ROM22 for storing programs, RAM23 used as a work area for calculation, EEPROM24 for storing installation data, IO port, A / D
The converter 25 and the like are connected. The EEPROM 24 stores in advance a correspondence table for determining the tube voltage at the time of photographing from the tube voltage at the time of fluoroscopy and the value of the tube current-time product as a function of the tube voltage at the time of photographing.

During fluoroscopy, X-rays emitted from the X-ray tube device 1 are projected onto a subject 3 through a visible diaphragm 2, transmitted through the subject 3, and then converted into a visible light image by an image intensifier 7. Further, this visible light image is displayed on the X-ray television device 8.
Incident on. The X-ray television device 8 converts the visible light image into an electric signal and sends the electric signal to the luminance signal output circuit 10. The luminance signal output circuit 10 selectively extracts the electric signal of the portion corresponding to the central portion of the visible light image and inputs it to the preamplifier 14 of the automatic exposure control device 11.

In the automatic exposure control device 11, the preamplifier 1
The output of 4 is EEPRO on the bus line of CPU21.
Compared with the fluoroscopic image brightness reference signal stored in advance in M24, if the fluoroscopic image brightness is too high, lower the X-ray condition,
If it is too low, increase the X-ray condition, and if it is within the appropriate range, the X
The fluoroscopic X-ray condition determination signal is determined so as to maintain the line condition, and this signal is sent to the X-ray high voltage generator 19 to determine the fluoroscopic tube voltage, so that the brightness of the fluoroscopic image is kept appropriate. As a result, the fluoroscopic X-ray condition determined by performing such control reflects the magnitude of X-ray absorption of the subject 3, and from this fluoroscopic X-ray condition,
The amount of X-rays required at the time of shooting can be calculated.

The X-ray condition at the time of photographing is determined by the following procedure. First, from the correspondence table stored in the EEPROM 24, the tube voltage RkV1 when the tube voltage (F-kV) is 70 kV and the tube voltage RkV2 when the tube voltage is 100 kv are calculated and linearly interpolated. A calculation is performed to determine the tube voltage for the fluoroscopic tube voltage determined above.
Then, from the value of the tube current time product as a function of the tube voltage stored in the EEPROM 24, the tube voltage (R
-KV) is 60 kV, 80 kv, 100 kv, 120 k
The value of each tube current time product at V is obtained, and the linear interpolation calculation is performed to determine the value of the tube current time product according to the above determined tube voltage, so as to give an appropriate film density. .

FIG. 3 is a graph showing a relational expression when determining the photographing tube voltage (R-kV) from the fluoroscopic tube voltage (F-kV), and FIG. 4 is the decided photographing tube voltage (R-kV). ) Is a graph showing a relational expression when the value (mAs) of the tube current time product is determined from FIG. When actually photographing, photographing is performed with the photographing tube voltage determined during fluoroscopy as described above. Regarding the tube current-time product, a tube current of a value that can be selected by the X-ray high-voltage device is selected below the allowable load of the X-ray tube device to be used, and the shooting time is too long or too short depending on the condition of the subject. Make sure to select the shooting time so that it does not pass.

As described above, in the X-ray fluoroscopic imaging apparatus of the present invention, the X-ray dose at the time of imaging is completely determined by the imaging tube voltage determined at the time of fluoroscopy, and is influenced by the output of the image intensifier during imaging. Will be decided without receiving any.

In this case, the value of the tube current time product which gives the appropriate film density is a value which is stored in the EEPROM 24 and which is a function of the conversion value of the fluoroscopy tube voltage and the shooting tube voltage and the shooting tube voltage. May be changed according to the purpose of photographing. Also, whether the interpolation calculation is linear, whether the tube current and shooting time are decomposed and controlled in order to obtain the required tube current time product, corresponding to the shooting tube voltage, and an appropriate film density is given. Whether or not the operator can appropriately select the value of the tube current time product, which is the value, from multiple values,
You may make it determine according to the objective of photography. Further, these conditions may be combined appropriately.

[0018]

As described above, according to the X-ray fluoroscopic imaging apparatus of the present invention, the fluoroscopic X-ray condition and the radiographic X-ray are used at the time of fluoroscopy only by the video signal of the X-ray television camera for observing the fluoroscopic image. It is possible to control the condition and. In addition, the automatic exposure control device of the X-ray fluoroscopy apparatus,
With a simple circuit configuration, there is an effect that adjustment becomes easy and stable operation can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a device of the present invention.

FIG. 2 is a block diagram showing a configuration of a peripheral circuit of a main control CPU of the device of the present invention.

FIG. 3 is a graph showing a relational expression for determining a photographing tube voltage from a see-through tube voltage.

FIG. 4 is a graph showing a relational expression when a tube current time product is obtained from an imaging tube voltage.

[Explanation of symbols]

 1 X-ray tube device 2 Movable diaphragm 3 Subject 4 Subject table 5 Film 6 Film holder 7 Image intensifier 8 X-ray TV device 9 Distributor 10 Luminance signal output circuit 11 Automatic exposure controller 12 X-ray controller 13 High voltage generator 14 preamplifier 15 F-kV setting circuit 16 R-kV setting circuit 17 R-TIME setting circuit 18 kV adjusting mechanism 19 switch 21 CPU 22 ROM 23 RAM 24 EEPROM 25 A / D converter

Claims (1)

[Claims] 1. An X-ray tube device for generating X-rays, a video recording means for recording an X-ray image after passing through a subject, and an image intensifier for converting an intensity distribution of the X-rays passing through the subject into an optical image. An X-ray television device for converting the optical image into an electric signal, a high voltage generator for generating a high voltage applied to the X-ray tube device, and an X-ray condition determining X-ray condition generated by the X-ray tube device. In an X-ray fluoroscopic imaging apparatus including a line control device and an automatic exposure control device that adjusts the X-ray dose for irradiating a subject, an X-ray during fluoroscopy is stored in a memory connected to a CPU that controls the operation of the automatic exposure control device. The correspondence table for determining the X-ray tube voltage at the time of imaging from the tube voltage and the tube current time product as a function of the X-ray tube voltage at the time of imaging are stored, and the output of the image intensifier of the image intensifier at the time of fluoroscopy is stored. All or part of the above X Enter the automatic exposure control device via the television apparatus, according to the intensity of the output electrical signal of the X-ray television apparatus in the automatic exposure control device fluoroscopic X
The X-ray tube voltage is determined, and at the time of shooting, the X-ray tube voltage corresponding to the fluoroscopic X-ray tube voltage is determined based on the correspondence table stored in the memory. A means for determining the value of the tube current time product corresponding to the tube voltage by performing an interpolation calculation based on the value of the tube current time product stored in the memory as a function of the X-ray tube voltage at the time of photographing. An X-ray fluoroscopic imaging apparatus characterized by: