JPS6049598A - X-ray photographing plant - Google Patents

Abstract

PURPOSE:To increase contrast and resolution by installing a detector of tube voltage and tube current applied to an X-ray tube, and selecting and reading-out a specified data sent from a memory with an outer input device, and controlling tube voltage of the X-ray tube based on both detected signals. CONSTITUTION:Tube voltage generated with a tube voltage generator 31 is applied to an X-ray tube 20. X-ray radiated with the X-ray tube 20 is transmitted through an object 22, and detected with a sensitive device 23. An auto exposure unit 25 outputs a signal which stops X-ray radiation based on the detected amount. Relation between tube voltage and exposure time by which a specified tube voltage is generated with the exposure time of a film 24 and the tube voltage is increased after a specified time is elapsed is stored in a memory P-ROM30 as a data corresponding to the object. A CPU29 reads out a specified data sent from the ROM30 based on input data of a photographing condition setting panel 24, and controls tube voltage of a device 31 based on signals detected with a tube voltage detector 33 and a tube current detector 34. By this process, contrast and resolution are improved.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention is directed to an X-ray tube having functions of generating a tube voltage to be applied to an X-ray tube and automatically controlling the tube voltage during X-ray photography. 1. This relates to a photographing device.

[Technical background of the invention and its problems]

Radiobiological experience and theory (According to Llt 9e, it has been established that in order to obtain the best X-ray image, it is necessary to vary the X-ray tube voltage in relation to the thickness of the object. (For example, in 1969, Munich-Berlierwin LJrban und Schwarze-n
Published by berg, 5lrablcn 1erapie
138, pp. 760-764, Norbcr t'M
i ke and Karl A.

1 (, 6is s s author - Di eBedeuL old r g
(I e r Me s s 11 II gvon
ROntgenspecktre+t fiirdie
Diagnos-1ik”).

By the way, as a method of increasing the X-ray tube voltage, for example, Japanese Patent Publication No. 57-640. Special Publication No. 57-19560゜Special Publication No. 57-21119. As disclosed in Japanese Patent Publication No. 57-21239, etc., by gradually decreasing the tube current,
A method of increasing the tube voltage is known.

However, in general, the response speed of the filament control loop in the X-ray imaging device Pr requires several hundred milliseconds to several seconds due to the thermal time constant of the filament (including the time required for stabilization); The rate at which the tube voltage gradually decreases and increases is a constant rate determined by the tube current at that time, and the tube voltage increase characteristics are as follows:
It is a linear change. For this reason, the following problems have arisen.

In other words, if an automatic exposure device is used, the tube voltage will rise regardless of the degree of darkening in the photograph or the quality of the contrast, and when a certain level of blackening is reached, the X-ray is blocked. As a result, although the prescribed degree of blackening can be obtained as a photograph, if the intensity of the X-rays transmitted through the subject after the start of photography is weaker than expected, the photography time will be extended. The image of organs becomes unclear. On the other hand, if the X8 intensity transmitted through the object is stronger than expected, the imaging time will be shortened and skeletal threads and the like will be imaged with poor contrast.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an X-ray device (a drum-shaped device 6) with good contrast and M image resolution.

[Summary of the invention]

Summary of the present invention for achieving the above object is an X-ray tube;
A tube voltage generating means for generating a visual voltage applied to the X-ray tube, and a tube voltage generating means for generating a visual voltage applied to the X-ray tube, and a tube voltage generating means for generating a visual voltage applied to the X-ray tube; In an X-ray imaging apparatus comprising an automatic exposure device that stops exposure, a first
a second detection means for detecting a tube current flowing through the X-ray tube; a second detection means for generating a predetermined tube voltage as the exposure time of the X-ray tube elapses; The relationship between the tube voltage value at which the voltage should be increased and the exposure time,
A storage means in which data on the number of VTLs corresponding to the subject is stored; an external input means for selecting specific data from the storage means; At the same time, the read data and the first data are read out. The apparatus is characterized by comprising a control means for controlling the tube voltage of the X-ray tube based on the detection signal of the second detection means.

[Embodiments of the invention]

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

FIG. 1 is a circuit diagram showing the Xi imaging device according to the present invention, and FIG. 16 shows the primary winding 14 and the secondary winding 158 of
It is a transformer consisting of ~15n.

The circuit constructed based on the transformer 160 primary winding 14 is as follows:
The diode 16 is connected in antiparallel, and the driver 26
The DC voltage source 11, together with the capacitor 17, is connected via the switching element 12 to the above-mentioned 1
This is a so-called voltage resonance type single-ended switch circuit connected in parallel to the i-line 14. Also 1,011
The secondary windings 153 to 15n of the transformer 130 are composed of two groups of diodes connected in series in the conductive direction, connected in parallel in the same polarity direction, and bridge-terminated between corresponding series connection points of the diode groups. The secondary windings 15a to 1 are connected as shown in FIG.
5n have their winding directions different from each other. In this way, the tube voltage generating means 61 that generates the tube voltage applied to the XIM tube 20 is configured.

Thus, the cathode sides of the diodes 18A1 and 18B10 disposed at the tips of the two diode groups are connected to one input end of the tube voltage detection means 6 and also connected to the anode 2Ua of the X-ray tube 20. be done. Furthermore, diodes 19An are arranged at the rear stage of each of the two diode groups.

The anode side of 19Bn is connected to the input end of the tube voltage detection means 6, and also to the filament 20b of the X-ray tube 20. Furthermore, the anodes t11 of the diodes 18An and 18Bn, which are located at the center of the two diode groups 01 and tFt, are grounded via the tube current detection means 64, and on the other hand,
The cathodes of the diodes 19A1 and 19B'l are directly grounded.

The tube voltage + (the output means 66 is the anode 20a of the X-ray tube 20
and the filament 20b, and the detection signal is sent to the tube voltage applied between the filament 20b and the
/l) (Analog/Digital) Through the conversion means 65, the central processing unit < c 'P U >-' which is the control means
29.

The tube current detection means 64 detects the lightning current flowing through the X-ray t#20, and its detection signal is input to the CPU 26 via the A/D conversion means 66 disposed at a subsequent stage. Ru.

The imaging condition setting panel 27, which is an external input means, is for manually inputting various conditions for X-ray imaging, which will be described later.The output thereof is input to the CPU 29, and the operation switch 67 is, for example, a two-stage switch. This command instructs the CPU 29 to prepare for photographing and to start photographing.

P-1(, OM(Pro
gramable Rea+I 0nly Memor
y, ) 50 stores the relationship between the tube voltage value and the exposure time to generate a predetermined tube voltage as the exposure time of the film 24 elapses and to increase the tube voltage after the elapse of the predetermined time. There is. Basically, when the subject to be imaged is the stomach, the ``U voltage is suddenly increased after a predetermined waiting time, depending on the subject's movement or depending on the body thickness, as shown in Figure 2a. If the data that can be photographed for a short period of time is available, and if the subject to be photographed is a vertebrae, as shown in the figure, a relatively low voltage can be used, and after maintaining a constant exposure time, depending on the thickness of the subject. Is it possible to suddenly increase the voltage and obtain data that cannot be obtained by shooting for a long time?
Furthermore, if the object to be imaged is the lungs, as shown in Figure C,
Data that can be obtained by high-voltage photography with a constant high tube voltage (140 to 150 KV) is stored, and data that changes somewhat depending on the subject's age, age, medical history, etc. is stored. . Data read out from the P-lLOM 30 in which such data is stored is then manually input to the CPU 29.

Further, the overload prevention means 62 is configured based on, for example, a memory element, and prevents the CP from exceeding the allowable load of the X-ray tube 20.
The upper limit of the operation of the driver 26 and the filament heating means 21 is set via U29.

A control signal from the CPU 29 is input to the driver 26 which outputs a pulse voltage to the switch element 12, and an automatic exposure device comprising a photosensitive means 23 interposed between the X-ray tube 20 and the film 24 is input. The output signal of Fj25 is input. Incidentally, the output signal of the automatic exposure device 25 is C
It is also input to l'U29.

The output of the filament heating means 21, which generates a voltage to be applied to the filament l-20b of the X-ray tube 20 based on the control signal of Ci' U 29, is applied to the filament l-20b of the X-ray tube 20 via the transformer 21. is applied to

Next, the operation of the x, (x7 imaging device) configured as described above will be explained.

First, the operator operates the imaging condition setting panel 27 and the operation switch 67 to prepare for X-ray imaging. That is, the imaging condition setting panel 27 sets the imaging conditions, for example, 1 year old, 220 years old, and gender.

The most suitable one considering your constitution, medical history, area to be photographed, etc.]I
^The shadow condition is set, and the sales item is selected by pressing the operation switch 67.
is recognized by the CPU 29. Soga CP
U29 also reads out specific data corresponding to the photographing conditions from the OM filter 0 of P-1, and also reads the specific data corresponding to the photographing conditions from the filament heating means 2.
1, and heats the filament 20b of the X-ray tube 20 (at the same time as heating the filament 20'b, a stator drive means (not shown) heats the anode 2' of the X-ray tube 20.
U a starts rotating).

In this state, the shooting preparation of this device is completed, and the CPU 29
At this point, a not-illustrated photographing preparation complete rung of the photographing condition setting panel 7 is lit to notify the operator of the photographing preparation stage.

Next, the operator operates the operation switch 67 again,
Start X-ray photography. In other words, (Subi operation switch 6
7, the CPU 29 drives the driver 26 based on the photographing conditions set in the photographing preparation stage described above. The switching element 12 is opened and closed by the pulse voltage output from the driver 26, and the high voltage generated in the secondary windings 15a to 15n of the transformer 13 is advected by a group of diodes, and is transferred to the anode 20a of the X-ray tube 2o. As soon as the voltage is applied between the X-ray tube 20 and the filament 20b, X-rays are emitted from the X-ray tube 20 (exposure starts).

Then, the CPU 29 uses the data read out from the P-ROM 30 (the relationship between the tube voltage and the exposure time predetermined according to the object to be photographed) and the JMr pressure detection means according to the photographing conditions set in the preparation stage. 66 current detection means 6
The driver 26 and, if necessary, the filament heating means 21 are controlled based on the detections (a) and 4) to control the tube voltage.

The X-rays transmitted through the object detected by the photosensitive means 26 are integrated by the automatic exposure device f\, 25, and when the value reaches a specific value, the automatic exposure device 25
The oscillation of the dora/r buff 6 is stopped by the output signal of
Radiation exposure stops (exposure of film 24 ends). still,
Here, the control content of the CPU 29 returns to the initial state.

In addition, during X-ray exposure, the tube voltage increases and an overload prevention means is provided to prevent the X-ray tube 20 from exceeding its allowable load before the automatic exposure means 25 stops the X-ray exposure (μs). 6
Driver 2 in CPU 29
6 and the upper limit of the it' control content for the filament heating means 21 is set according to the required suction.

In this way, the optimum photographing conditions for the subject are set in advance, and based on these, the CPU 2□9 instantaneously controls the rate of increase of the tube voltage to be applied to the X-ray tube 20. It becomes possible to irradiate the optimal XaI site to the area to be imaged, and a good X-ray photograph can be obtained.

It goes without saying that the present invention is not limited to the above-mentioned example of the actual Mf4, and that modifications can be made as appropriate within the scope of the invention.

For example, in the embodiment described above, the snow forming pressure control of the X-ray tube 20 by the CPU 29 is continuously increased (as shown in FIG. 2), but is not limited to this, and may be increased stepwise.

Further, the control by the CPU 29K in the above embodiment was performed based on the relationship between time and tube voltage stored in advance in the P-ROM 30, but it By adding a P-ROM and performing tube current control as well as tube voltage control, even more precise control can be achieved.

Furthermore, in the embodiment described in Ail, the CPU is used as a control means.
29 is used, but the present invention is not limited to this, and may be configured by hardware, or may be configured by firmware based on microprogramming.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to irradiate the optimal X-ray dose to the imaging part of the subject, and thick subjects can be imaged in a shorter time than with conventional equipment, so both contrast and resolution are improved. An X-ray imaging device that can obtain good X-ray pictures can be -1,1I8 (Jl).

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an X-ray imaging device μ according to the present invention,
FIG. 2 is a characteristic diagram showing the relationship between exposure time and tube voltage of the device shown in FIG. 1. 20... X-ray tube, 22... Subject, 26...
Photosensitive means, 24. Film, 25. Automatic 51z output device, 27. Shooting condition setting panel (external input means).
29 , CPU (control means), 30 =・
P-ROM (storage means), 61...tube voltage generation means, 6ro...tube voltage detection means (first detection means),
64...Tube current detection means (second detection means).

Claims (1)

[Claims] an X-ray tube; a blue voltage generating means for generating a tube voltage applied to the X-ray tube; Based on the
In the radiography apparatus, a first detection means for detecting a tube voltage applied to the X-ray tube;
a second detection means for detecting tj IJiC, and generating a predetermined tube voltage as the exposure time of the X-ray tube elapses;
31r After a certain period of time has elapsed, a storage means in which a plurality of data is stored, which is the relationship between the voltage value and the exposure time, according to the subject, and the relationship between the voltage value and the exposure time to which the vehicle pressure should be increased; Based on an external input means for selecting specific data and a signal inputted by this external input means, a specific j-time is read out from the storage means, and the read data and the first . An X-ray imaging apparatus characterized by comprising a control means for controlling a tube voltage of the X-ray tube based on a detection signal of the second detection means.