JP2000012280A - X-ray cineradiographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cineradiographic film with constant radiation quality and a satisfactory contrast while keeping the film density constant. SOLUTION: The pulse width of the X-ray emission signal from an X-ray emitting circuit 53 is compared with the pulse width of the signal from a set pulse width timer 44 by a comparator 58 to provide the difference signal, and this difference is transmitted to a tube voltage automatic setting circuit 64, tube current automatic setting circuit 65, and an A/D converter 38 through switches 61-63 controlled by an output circuit 39 on the basis of the data read from a T-R condition data memory 35 as the optimum control for the thickness of a subject 10, and the control of tube voltage, tube current and photographing time are controlled on the basis of the optimum control method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an X-ray imaging apparatus, and more particularly, to an X-ray cine imaging apparatus that captures a moving image to capture the motion of the heart and blood vessels.

[0002]

2. Description of the Related Art Conventionally, X-ray cine imaging using a cine camera apparatus has been performed for X-ray diagnosis of the heart and the vascular system of the heart in order to cope with rapid movement.

[0003] An X-ray cine imaging apparatus uses an image intensifier which converts transmitted X-rays of a subject into a visible light image. It is said that photographing with a tube voltage of 50 kV to 80 kV gives a good contrast photograph.

In a conventional X-ray cine radiographing apparatus, the radiographing time (pulse width) is determined according to the film speed of the cine camera, and the start conditions (tube voltage and tube current) for X-ray cine radiography are set by the surgeon. Then, shooting is started under these conditions. During imaging, the subject changes due to injection of a contrast agent or the like, and X-ray conditions are controlled to keep the imaging density of the cine film constant with respect to the change. First, the X-ray emission time is controlled by a photo timer. Next, when the imaging time changes, the tube voltage is adjusted so that the actually measured imaging time approaches the imaging time (pulse width) initially set by the operator. Is changing. Also,
In order to sufficiently extract the rating of X-rays, a system (iso-watt control) in which a constant load is always applied to an X-ray tube by changing a tube current in accordance with a change in a tube voltage is performed.

Therefore, except for a transient state in which the photographing time changes, the tube voltage RkV, tube current RmA, and photographing time Rs at the time of cine photographing with respect to the human body thickness (subject thickness).
The relationship of ec converges to the state shown in FIG. That is, when the human body thickness is equivalently increased by the contrast agent or the like,
The tube voltage rises and the tube current decreases accordingly, with the result that the imaging time is kept constant.

[0006]

However, according to the conventional method, the density of the film is kept constant irrespective of the state of the subject, but there may be a problem in image quality in terms of contrast. Since the same control method is used for any object thickness and test site, if the X-ray absorption of the object is small, for example, depending on the region where the object thickness is small, the X-ray emission time is set by a photo timer. Therefore, the tube voltage decreases and the tube current increases (iso-watt control). As a result, the tube voltage is greatly reduced, and the image quality of the film becomes too contrasting to be used for diagnosis. Conversely, when the thickness of the subject is slightly increased, the tube voltage rises and an image with no contrast is obtained despite the use of an X-ray tube with a large rating, despite the fact that there is a margin in the rating.

Further, during imaging, since the tube voltage is changed in response to a change in the subject due to injection of a contrast agent or the like, an image having a changed radiation quality is obtained. In an extreme case, there is a problem that diagnosis is hindered.

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide an X-ray cine photographing apparatus improved so as to obtain a cine photographing film having a constant line quality and good contrast while maintaining a constant film density. I do.

[0009]

In order to achieve the above object, in an X-ray cine radiographing apparatus according to the present invention, an X-ray tube and a tube voltage and a filament heating current applied to the X-ray tube are provided. A high voltage generator capable of adjusting voltage and tube current, an image converter for converting transmitted X-rays of a subject into a visible light image, a TV camera and a cine camera for capturing the visible light image, and An optical system for switching between a TV camera and a cine camera, an image monitor device for transmitting a video signal output from the TV camera to display a perspective image, and an optical system inserted into the optical system for detecting the luminance of the visible light image A fluoroscopic converter for converting an electric signal into an electric signal, and controlling the high voltage generator in accordance with the luminance of the video signal during fluoroscopy to change the tube voltage applied to the X-ray tube, thereby making the luminance of the displayed image constant. control And a first storage device for storing the tube voltage obtained when the image brightness converges for each subject thickness in advance in fluoroscopy in relation to the subject thickness. The data of the obtained tube voltage, tube current, and photographing time are stored for the subject thickness, and any of a control method for controlling the tube voltage, a control method for controlling the tube current, and a control method for controlling the photographing time is optimal. A second storage device for storing the information regarding the range of the subject thickness, and generating a X-ray start signal in response to a shutter pulse signal from the cine camera at the time of cine imaging to start applying a tube voltage from the high voltage generator to the X-ray tube. A pulse generator for integrating the output of the photoelectric converter during cine imaging and generating an X-ray cutoff signal when the integrated value reaches a set value to generate the high voltage A first timer for stopping application of a tube voltage from the X-ray tube to the X-ray tube; The thickness of the subject is estimated from the storage device, and the data and control method of the tube voltage, the tube current and the photographing time corresponding to the estimated subject thickness are obtained from the second storage device. When the time from the X-ray start signal to the X-ray cutoff signal changes due to a change in the subject during cine imaging, the time and the set imaging time are set. Cine photography that controls the tube voltage and tube current based on the set control method according to the difference, and also monitors the tube voltage, tube current and the difference to change the control method It is characterized by having a control device.

When fluoroscopy is performed on an actual subject prior to cine imaging of the subject, the tube voltage is controlled and converged by the operation of the fluoroscopy control device so that the brightness of the displayed image becomes constant. Based on the tube voltage, the subject thickness can be estimated from the first storage device that stores the relationship between the tube voltage at the time of convergence and the subject thickness. In the second storage device, optimal tube voltage, tube current and photographing time data at the time of cine photographing are stored with respect to the subject thickness, and a control method for controlling the tube voltage and a control method for controlling the tube current Which of the control methods for controlling the photographing time is optimal is stored with respect to the range of the subject thickness.
Can set the tube voltage, tube current, photographing time, and control method at the start of cine photographing. In other words, at the start of cine imaging, an X-ray condition and a control method optimal for the actual thickness of the subject are determined, so that the convergence time can be reduced. for that reason,
Even when the subject is thin, such as a baby, an optimal start condition and control method can be selected for the thickness of the subject before the start of shooting, and shooting can be started with an appropriate image quality.

When the subject changes due to injection of a contrast agent or the like during cine radiography, the time until the X-ray cutoff signal is generated by the action of the photo timer changes, and the time from the X-ray start signal to the X-ray cutoff signal is set. In accordance with the difference from that performed, control of the tube voltage, the tube current, and the imaging time is performed based on the set control method. By controlling the X-ray conditions by the control method according to the subject thickness in this manner, the fluctuation range of the tube voltage is suppressed, and a cine film having a stable image quality and a high-quality image with a high contrast can be obtained.

[0012]

Next, embodiments of the present invention will be described in detail with reference to the drawings. 1 and 2
FIG. 1 is a block diagram showing an embodiment of the present invention. FIG.
FIG. 2 mainly shows a control system at the time of cine imaging, and FIG. 2 shows a control system at the time of obtaining a subject thickness from fluoroscopic conditions during fluoroscopy. 1 and 2, X-rays are emitted from an X-ray tube 11 to a subject 10, and the X-rays transmitted through the subject 10 enter an image intensifier 12. The image intensifier 12 converts an X-ray image incident on the incident fluorescent screen into a visible light image and displays it on the output fluorescent screen. The visible light image displayed on the output phosphor screen of the image intensifier 12 is guided to the optical system 14 through the primary lens 13 and is switched by the optical switch to the secondary lens 15.
And the secondary lens 16.

At the time of cine photography, an image is formed on the film of the cine camera 51 through the secondary lens 16 as shown by the arrow in FIG. 1, and when viewed through the camera, the image is taken by the television camera through the secondary lens 15 as shown by the arrow in FIG. An image is formed on the imaging surface of the tube 17. The visible light image formed on the imaging surface of the imaging tube 17 is
The image is read out by the camera control unit (CCU) 18, converted into a video signal, transmitted to the image monitor 19, and a perspective image is displayed. The CCU 18 also
A luminance proportional signal is created and output to the fluoroscopy control device 24 (FIG. 2).

The X-ray tube 11 is supplied with a high tube voltage from a high voltage generator 21 and a filament heating current. This high voltage is controlled by the inverter controller 23, and the filament heating current is controlled by the filament heating controller 22.

First, in order to determine the relationship between the thickness of the subject 10 and the fluoroscopic conditions, fluoroscopy is performed using a phantom as the subject 10. At this time, as shown in FIG. 2, when the operator performs a fluoroscopy operation, an X-ray emission signal is input to the inverter controller 23. As a result, the inverter starts oscillating at a frequency corresponding to the start fluoroscopic conditions (fluoroscopic tube voltage and fluoroscopic tube current) output from the fluoroscopic control device 24, and its output is sent to the high voltage generator 21 to reduce the high voltage. appear. This high voltage is applied to the X-ray tube 11 as a tube voltage to generate X-rays. At this time, the visible light image output from the image intensifier 12 is input to the image pickup tube 17 by the optical switch of the optical system 14 switched to the secondary lens 15 side, and a video signal is generated from the CCU 18. This is sent to the image monitor 19 and the CCU 1
8 is sent to the fluoroscopy controller 24.

In accordance with the luminance proportional signal input from the camera control unit 18, the fluoroscopy control device 24 performs a fluoroscopic condition (a fluoroscopic tube voltage FkV, a fluoroscopic image, etc.) such that a fluoroscopic image displayed on the image monitor device 19 has an optimum luminance. Tube current Fm
A) is obtained and the signal is sent to the inverter controller 23.
The signal representing the fluoroscopic tube voltage FkV is also input to the A / D converter 38 of the microcomputer 31, and the fluoroscopic tube voltage FkV is read and displayed on a fluoroscopic tube voltage display (not shown).

The microcomputer 31 includes a CPU 32
FT data memory 34, TR condition data memory 35, FVR data memory 36, program memory 37 connected to the bus line 33,
/ D converter 38, output circuit 39, D / A converter 41
43, and a set pulse width timer 44. The program stored in the program memory 37 is read into the CPU 32 via the bus line 33,
When the U32 operates according to the read program, the operation as the microcomputer 31 is performed.

In a device for photographing in a hospital that is actually installed, fluoroscopy using a human equivalent phantom is performed. When a phantom of a certain thickness is to be seen through, the operation of the above-mentioned automatic see-through brightness control loop provides an optimum viewing tube voltage. That is, when the brightness of the image displayed on the image monitor device 19 converges optimally, the fluoroscopic tube voltage FkV at that time is controlled by the A / D converter 38 under the control of the CPU 32.
Is written to the FT data memory 34 via At the same time, the phantom thickness at this time is also written into the FT data memory 34 by manually operating a setting device (not shown) or automatically. Yet another 4
The fluoroscopy conditions are actually measured at different phantom thicknesses. By this series of operations, the data shown in FIG.
4 is stored.

Thus, the FT data memory 34 has
As shown in FIG. 3, the relationship between the subject thickness (human body thickness) and the fluoroscopic tube voltage FkV in each fluoroscopic mode is stored. A to E, A ′ to E ′, and A ″ in FIG.
E ″ is the optimum fluoroscopic tube voltage for each fluoroscopic mode at each of the five thicknesses. The relationship between fluoroscopic tube voltage FkV and fluoroscopic tube current FmA in each fluoroscopic mode is as shown in the characteristic diagram of FIG. is there.

Next, the relationship between the subject thickness and the photographing start condition for cine photographing is obtained by using a human equivalent phantom, and written in the TR condition data memory 35. At this time, a phantom having the phantom thickness at the time of obtaining the above-described perspective conditions is arranged as the subject 10, and the shooting conditions are set by a shooting condition setting device (not shown) so that a desired cine photograph is obtained at each thickness. Try cine photography. Thereby, five human body thicknesses tA, tB, tC, t
Optimal shooting start conditions at D and tE, shooting tube voltage R
The kV, the imaging tube current RmA, and the imaging time Rsec are obtained, for example, as shown in FIGS. 5A, 5B, and 5C, and the data is written to the TR condition data memory 35.

FIG. 5A shows the relationship between the subject thickness and the starting tube voltage, FIG. 5B shows the relationship between the subject thickness and the starting tube current, and FIG. 5C shows the subject thickness. FIG. 6 is a characteristic diagram showing a relationship between the image capturing time (pulse width) at the start and the start time. Points vA to vE, points aA to aE, and points sA to sE in FIG.
These are the conditions corresponding to the thickness at point E, that is, the imaging tube voltage, imaging tube current, and imaging time.

FIG. 5A, FIG. 5B and FIG.
With respect to the change of the subject 10 during cine shooting, the subject thickness tA
During the period from tB to tB, the tube current and the photographing time are kept constant, and only the tube voltage is changed to suppress the decrease in the tube voltage. During tC to tD, the tube voltage / tube current (large) is kept constant, and only the imaging time is changed to keep the tube voltage constant.
It is also shown that the tube current (large) and the photographing time (long) are fixed and the tube voltage is changed again to respond to the change of the object during the thicker object thickness tD to tE.

Selection of an automatic control method for changing only the tube voltage between the object thicknesses tA and tB,
Selection of an automatic control method for changing only the tube current during tC, selection of an automatic control method for changing only the photographing time between the object thicknesses tC to tD, and further thicker object thickness tD to
The selection according to the subject thickness of the automatic control method of selecting the automatic control method for changing only the tube voltage again during tE is also stored in the TR condition data memory 35.

After writing to the FT data memory 34 and the TR condition data memory 35,
A cine image of the actual subject 10 is taken. At the time of cine imaging, first, fluoroscopy for positioning is performed.
With the subject 10 positioned in front of the image intensifier 12 and the optical switch of the optical system 14 switched to the image pickup tube 17 side, a transparent switch (not shown) is turned on, and the inverter control is performed in the same manner as in the above-described transparent control. An X-ray emission signal is input to the generator 23 and the X-ray tube 11 is transmitted from the high voltage generator 21.
To apply a high voltage to the subject 10 and irradiate the subject 10 with X-rays.
Perform fluoroscopy for positioning before cine imaging. At this time, C
The fluoroscopy control device 24 according to the luminance proportional signal from the CU 18
Controls the fluoroscopic conditions (fluoroscopic tube voltage FkV) so that the image displayed on the image monitor device 19 has a predetermined luminance. Thus, the fluoroscopic tube voltage FkV corresponding to the thickness of the subject 10 is automatically determined, and the luminance is stabilized.

The automatically set fluoroscopic tube voltage FkV
Is read by the A / D converter 38 of the microcomputer 31 and the F-T data memory 3
4 are accessed. As described above, the FT data memory 34 stores data on the relationship between the subject thickness and the tube voltage at the time of fluoroscopy.
A thickness of 0 will be estimated. When the actual thickness of the subject 10 is estimated, the CPU 32 calculates the estimated thickness as T
-Optimal shooting start conditions (tube voltage, tube current, shooting time) at the time of cine shooting corresponding to the estimated thickness of the subject 10 by matching with the data stored in the R condition data memory 35.
Ask for.

After this positioning perspective has been completed,
Cine photography is started. At the time of this cine imaging, as shown in FIG. 1, signals representing the tube voltage RkV and the tube current RmA for cine imaging are sent from the tube voltage automatic setting circuit 64 and the tube current automatic setting circuit 65 to the inverter controller 23. Are also sent to the A / D converter 38 of the microcomputer 31. At the start of cine imaging, the tube voltage automatic setting circuit 64 and the tube current automatic setting circuit 65
The tube voltage initial value and the tube current initial value obtained from the above-mentioned TR condition data memory 35 are sent through the D / A converters 42 and 43, and the X-ray tube 11
Are the initial values of the tube voltage RkV and the tube current RmA. Further, the above-mentioned TR condition data memory 3
5 is set in the set pulse width timer 44.

At the time of this cine photographing, a shutter pulse signal is generated from the cine camera 51 and is input to the pulse generator 52. The pulse generator 52 generates an X-ray start signal in response to the input shutter pulse signal, and sends it to the X-ray emission circuit 53 and to the set pulse width timer 44.

The X-ray radiation circuit 53 supplies an X-ray radiation signal to the inverter controller 23. The X-ray emission circuit 53 starts up the X-ray emission signal when the X-ray start signal is input,
When the X-ray cutoff signal is input, the X-ray emission signal falls. The X-ray cutoff signal is generated when the exposure density of the film of the cine camera 51 reaches the set value when the integrated value of the brightness of the output image of the image intensifier 12 reaches a predetermined value.

This X-ray cutoff signal is generated by a photo timer. That is, a photomultiplier tube (PMT) 54 inserted into the optical system 14, an integrator 55, and a concentration setting device 56
And the comparator 57 constitute a phototimer. A part of the output light of the image intensifier 12 is guided to the photomultiplier tube 54, and the photocurrent output is integrated by a photocurrent integrator 55. A set value of the film density is set in the density setter 56 in advance, and the set value output from the density setter 56 and the integrated value from the photocurrent integrator 55 are compared by a density comparator 57. When the integrated value exceeds the set value, an X-ray cutoff signal is generated from the concentration comparator 57 and sent to the X-ray emission circuit 53. The X-ray emission signal falls in response to the X-ray cutoff signal, and the generation of the high voltage is stopped through the inverter controller 23.
X-rays from the cine film are blocked, and as a result, the exposure density on the cine film is maintained at the value set by the density setting device.

On the other hand, when the X-ray start signal from the pulse generator 52 is sent to the set pulse width timer 44, the timer operation is started from the input time. The set pulse width timer 44 outputs a signal that rises at the time of input of the X-ray start signal and falls when the time set as the imaging time has elapsed, and sends this signal to the comparator 58. The comparator 58 is supplied with an X-ray emission signal representing the actual X-ray emission time, and generates an output corresponding to the difference between the pulse widths of the two input signals. That is, this difference signal represents the difference between the actual X-ray emission time and the set emission time.

The difference signal from the comparator 58 is passed through switches 61, 62 and 63 to the automatic tube voltage setting circuit 6 respectively.
4. Automatic tube current setting circuit 65 and A / D converter 38
Sent to These switches 61 to 63 are controlled by an output from an output circuit 39 controlled by the CPU 32 based on the data in the TR condition data memory 35. When the subject thickness is between tA and tB, a selection signal for changing the tube voltage in response to a change in the subject 10 during cine shooting is output from the output circuit 39, and the switch 61 is turned on. Similarly, during the period from tB to tC, a selection signal for changing the tube current in response to the change of the subject 10 is output from the output circuit 39, and the switch 62 is turned on. Subject 1 during tC to tD
A selection signal for changing the photographing time with respect to the change of 0 is output from the output circuit 39, and the switch 63 is turned on. During the thicker object thickness tD to tE, a selection signal for changing the tube voltage again in response to the change of the object 10 is output from the output circuit 39, and the switch 61 is turned on.

Here, the operation during cine shooting will be described by taking as an example the case where the object thickness is between tB and tC and the switch 62 is turned on. At this time, the difference signal from the comparator 58 is sent to the tube current automatic setting circuit 65 via the switch 62. Therefore, the tube current automatic setting circuit 65 generates a tube current signal for increasing or decreasing the tube current according to the input difference signal, that is, according to the error between the actually measured X-ray emission pulse width and the set pulse width. Output. Since the photographing condition at the start is the optimum condition determined from the condition at the time of fluoroscopy, the difference signal at this time is zero. Therefore, cine photography is continued while maintaining this condition.

When the contrast agent is injected and the state of the subject 10 changes in the direction of increasing the thickness, the actually measured X-ray emission pulse width becomes longer than the pulse width from the set pulse width timer 44, and the difference signal from the comparator 58 becomes +. , And the tube current signal from the tube current automatic setting circuit 65 rises. This tube current signal is
The microcomputer 3 together with the inverter controller 23
1 A / D converter 38. The microcomputer 31 calculates a filament heating value from the input tube current signal value and tube voltage value, outputs a filament heating signal from the D / A converter 41, and inputs the filament heating signal to the filament heating controller 22. By controlling the high voltage generator 21 by the filament heating controller 22, the D / A converter 4
The filament of the X-ray tube 11 is heated by the output value from 1, and the tube current increases.

Thus, the tube current rises and the X-ray intensity rises, and the next frame is photographed in that state. As described above, when the density setting value is reached, X-rays are cut off and the film density is maintained at an appropriate value. Then, the actually measured X-ray emission pulse width is compared with the pulse width from the set pulse width timer 44, and the above-described tube current rise is repeated until the difference signal from the comparator 58 becomes zero. When the tube current increases and the time required for the integrated value of the output of the photomultiplier tube 54 to reach the set value is shortened, and the difference signal from the comparator 58 becomes zero, cine photography continues while this tube current is maintained. Will be done.

The microcomputer 31 monitors the value of the tube current signal input to the A / D converter 38. If the tube current exceeds mA1 in FIG. 5B, the tube current is increased. Constant value mA without increasing
Set to 1 and switch to an automatic control method in which the film density is increased by extending the photographing time. That is, the case where the tube current exceeds mA1 is the case where the subject thickness exceeds tC.
The automatic control method for changing the photographing time in response to the change in the subject 10 is selected, and the output circuit 39
The switches 61 and 62 are turned off and the switch 63 is turned on in response to the output from. Therefore, FIG.
As in the case of the thicknesses tC to tD of (b) and (c), only the photographing time Rsec is changed while the tube voltage and the tube current are kept constant.

At this time, the difference signal from the comparator 58 is input to the A / D converter 38 via the switch 63 which is turned on, and is monitored. Then, the CPU 32 can determine that the photographing time Rsec has reached sD in FIG. 5C, and at that time, the automatic control method for changing only the tube voltage at the thicknesses tD to tE is selected, and the output circuit 39 is selected. Switch 61 is turned on by the output from
Is turned off. Therefore, at this time, the tube voltage automatic setting circuit 64 performs control to increase or decrease the tube voltage according to the difference signal from the comparator 58.

When the cine imaging is continued only by controlling the tube current and the tube current becomes small and becomes smaller than mA2 in FIG. 5B, similarly,
An automatic control method for changing only the tube voltage at the thickness tA to tB is selected, the switch 61 is turned on by the output from the output circuit 39, the switches 62 and 63 are turned off, and the difference signal from the comparator 58 is output. Automatic tube voltage setting circuit 64
Control for raising or lowering the tube voltage.

As described above, the tube voltage, the tube current, and the photographing time are automatically controlled in response to the change in the state of the subject 10, and a series of cine photographing is completed while selecting the control method. Therefore, although depending on the rating of the X-ray tube, the tube voltage can be kept constant over most of the normal object thickness, that is, the thickness between tB and tD in FIG.
It is possible to obtain a cine film having a high-contrast image.

Automatic control with improved image quality can be similarly performed not only when using a cine film using a cine film but also when using a cine camera that performs digital cine shooting in combination with an XTV camera and a digital radiography apparatus. . Further, in the case of pulse fluoroscopy, which radiates X-rays in a pulsed manner similarly to cine imaging, if this control method is used, the tube voltage becomes constant even when the C-arm is rotated to move obliquely from the front of the subject. An easy-to-view transparent image of the same quality is obtained.

[0040]

As described above, according to the X-ray cine radiographing apparatus of the present invention, the optimum X-ray conditions and the optimum control method corresponding to the estimated thickness of the actual subject are determined at the time of starting the cine radiography. , Cine imaging can be started from the beginning under optimum X-ray conditions. In addition, even if the subject changes due to injection of a contrast agent or the like, the control method is changed to an optimal control method for the changed subject thickness to control the X-ray conditions. It is possible to obtain a cine film having a high-contrast image.

[Brief description of the drawings]

FIG. 1 is a block diagram mainly showing a control system at the time of cine shooting in an embodiment of the present invention.

FIG. 2 is a block diagram mainly showing a control system during fluoroscopy in the embodiment;

FIG. 3 is a graph showing the relationship between subject thickness and fluoroscopic tube voltage under fluoroscopic image brightness automatic adjustment.

FIG. 4 is a graph showing a relationship between a fluoroscopic tube voltage and a fluoroscopic tube current in each fluoroscopic mode.

FIG. 5 is a graph showing respective characteristics of a tube voltage, a tube current, and a photographing time with respect to a subject thickness during cine photographing in the embodiment.

FIG. 6 is a diagram showing the thickness of a conventional subject during cine photography.
5 is a graph showing characteristics of a tube voltage, a tube current, and an imaging time.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Subject 11 X-ray tube 12 Image intensifier 13 Primary lens 14 Optical system 15, 16 Secondary lens 17 Image pickup tube of TV camera 18 Camera control unit 19 Image monitor 21 High voltage generator 22 Filament heating controller 23 Inverter control Device 24 perspective control device 31 microcomputer 32 CPU 33 bus line 34 FT data memory 35 TR condition data memory 36 FVR data memory 37 program memory 38 A / D converter 39 output circuit 41 to 43 D / A converter 44 Set pulse width timer 51 Cine camera 52 Pulse generator 53 X-ray emission circuit 54 Photomultiplier tube 55 Integrator 56 Concentration setter 57 Concentration comparator 58 Pulse width comparator 61-63 Switch 64 Tube voltage automatic setting circuit 65 Tube power Auto setting circuit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideki Fujii 1-chome, Nishi-no-Kyowa-cho, Nakagyo-ku, Kyoto-shi, Kyoto F-term (reference) 4C092 AB04 AC03 AC14 CC02 CC12 CD02 CD03 CD06 CE11 CE12 CF47 CG05 4C093 AA13 AA16 CA01 CA04 EB02 EB10 FA13 FA15 FA18 FA19 FA43 FA44 FA45 FB09 FC04 FD01 GA01 GA06

Claims (1)

[Claims] 1. An X-ray tube, a high voltage generator capable of adjusting a tube voltage and a tube current for applying a tube voltage and a filament heating current to the X-ray tube, and a visible light image of transmitted X-rays of a subject. And a T for photographing the visible light image
A V camera and a cine camera, an optical system for guiding the visible light image by switching between the TV camera and the cine camera,
An image monitor device to which a video signal output from a V camera is sent to display a fluoroscopic image, a photoelectric converter inserted into the optical system for detecting the luminance of the visible light image and converting it into an electric signal; A fluoroscopy control device for controlling the high-voltage generator according to the signal luminance to change the tube voltage applied to the X-ray tube so as to make the luminance of the displayed image constant, and a subject thickness previously determined during fluoroscopy. Storage device for storing the tube voltage when the image brightness converges in each case in relation to the subject thickness, and data of the tube voltage, tube current, and photographing time previously determined as the optimum values at the time of cine photographing With respect to the subject thickness,
A second storage device for storing which of the control method for controlling the tube voltage, the control method for controlling the tube current, and the control method for controlling the photographing time with respect to the range of the subject thickness, and a cine camera during cine photographing. A pulse generator for generating an X-ray start signal in response to the shutter pulse signal of the above, and starting application of a tube voltage from the high voltage generator to the X-ray tube; When the value reaches a set value, an X-ray cutoff signal is generated to stop the application of a tube voltage from the high voltage generator to the X-ray tube, and a fluoroscopy of the subject prior to actual cine imaging of the subject Is performed, the subject thickness is estimated from the first storage device based on the tube voltage converged by the fluoroscopy control device, and the tube voltage, tube current, and imaging time corresponding to the estimated subject thickness are estimated. Data and control method of the second tube voltage at the start of the cine imaging seeking from the storage device, and sets the tube current and exposure time and control method, X from the X-ray start signal by a change of the subject in cine imaging
When the time to the line cutoff signal changes, the tube voltage and the tube current are controlled based on the set control method according to the difference between the time and the set shooting time, and the tube voltage And a cine imaging control device that monitors a tube current and the difference and also changes the control method.