JPS59193677A - X-ray television device - Google Patents

Abstract

PURPOSE:To obtain accurate diagnostic information by changing the beam current of an image pickup tube and the gain of an amplifier means in synchro- nizing with the timing of X-ray exposure so as to process a video signal with a specified level and high S/N ratio without decreasing the service life of the image pickup tube. CONSTITUTION:An exposure timing signal from an X-ray exposure commanding device 13 is inputted to an X-ray controller 1 and also to a gain switching means 14 and an image pickup tube beam current switching means 15. The switching means 14 changes the gain of an amplifier means 9 amplifying a video signal current Is from an X-ray TV camera 7 based on the exposure timing. Further, the switching means 15 changes the beam current flowing to the image pickup tube 8. The video signal is processed at the specified level with high S/N without decreasing the service life of the image pickup tube 8, and the accurate diagnostic information is applied to a picture storage device 11 and a picture operation processor 12.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to an X-ray television apparatus.

[Technical background of the invention and its problems]

A conventional X-ray television apparatus is shown in FIG. 1C-2.

In FIG. 1 (2), X-rays emitted from the X-ray generator 2 controlled by the X-ray controller 112 pass through the subject 6 and the bed device 4, and the transmitted X-ray image is an image inden. The image pickup tube 8 (hereinafter referred to as "rTV camera") is converted into an optical image by the fire 5, and is then housed in an X-ray television camera (hereinafter referred to as "rTV camera") 7 via the optical system 6. obtains a video signal current by capturing the optical image formed.This video signal current is
After being amplified by the amplification means 9C2, the X-ray television monitor (hereinafter abbreviated as rTV monitor) 10.1 [
! The image data is input to an image recording device 11 and an image calculation processing device 12, and is used for image display, image recording, and calculation processing, respectively. Further, the X-ray exposure command device 16 sends an exposure timing signal to the X-ray control device 1 to control the amount of X-ray exposure from the X-ray generator 2 . Here, when the X-ray exposure amount of the X-ray generator 2 is high (high exposure) and when the X-ray exposure amount is small (low exposure) are alternately cut out, especially when the high exposure Based on the X-ray image obtained at the time, image display, m-image recording, and arithmetic processing are performed.Meanwhile, the video signal current IS of the image pickup tube 8 is regulated by the beam Ichihara 1bl2 of the image pickup tube 8, It is expressed as the following equation.

IS = a ・Ib + b −−−−−−−
-.(1) Here, a and b are constants determined by the image pickup tube.

Further, when the gain of the amplifying means 9 is G, the video signal level V is expressed as follows.

V2G-Is (2) At this time, the S/N ratio is expressed as C2 as in the general C quadratic equation.

IS where A and B are constants. First of all, according to the formula s1, as the beam DC current Ib increases, the video signal current ■S increases,
Furthermore, from equation (2), it can be seen that as the video signal current IS increases, the visual disturbance signal level V increases, and further, as shown in equation (3), as the video signal current IS increases, the S/N ratio increases. That is, when the signal current IS is increased by high exposure of X-rays, a video signal with a high S/N ratio is obtained, and its level is also increased (assuming the amplification factor is constant).

By the way, in general, if the beam current of an image pickup tube is constantly increased, its characteristics will deteriorate and its life will be shortened. For this reason(
2. Conventionally, the beam current is set to a predetermined level ≦2, or the so-called automatic beam optimization circuit (hereinafter abbreviated as rABOJ) that automatically controls the beam current according to the amount of X incident on the image pickup tube (C2) ) was adopted. However, if the beam current is always set at the specified level C2, there is a problem that false signals will be generated due to insufficient beam during high exposure (2).On the other hand, if the ABO is used, the circuit will be expensive. There were problems such as.

Further, it is desirable that the TV monitor, the image recording device, and the arithmetic processing device f2 receive video signals of a specified level. This is because if the input video signal is too crystalline or too low, the target diagnostic information may become inaccurate. For this reason, conventionally, when the beam current is simply increased, the simultaneous≦two video signal levels also increase, and this has had to be adjusted to a specified level (two times) each time.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned situation C, and it is possible to achieve high S/S/R at a specified level without shortening the life of the image pickup tube.
It is an object of the present invention to provide an X-ray television device that can obtain accurate diagnostic information by processing a video signal with an N ratio.

[Summary of the invention]

F]'J The outline of the present invention for achieving the purpose of RCC is as follows: An X?FM television camera that captures an optical image obtained based on X-rays transmitted through a subject and outputs a video signal; An X-ray television device for displaying the video signal on an X-ray television monitor after amplifying the video signal by an amplifying means≦2, an imaging tube beam iL that controls the beam current of the imaging tube in the X-ray television camera. flow switching means;
and gain switching means for controlling the gain of the amplification means,
The image pickup tube beam current switching means and the gain switching means are operated in synchronization with the X-ray exposure timing.

[Embodiments of the invention]

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

FIG. 2 is a block diagram showing an apparatus according to an embodiment of the present invention. Components in C2 of the same figure that have the same functions as those in FIG.

In FIG. 2, the exposure timing signal output from the X-ray exposure command device 16 is input to the X-ray control device 1, and is also input to the gain switching means 14 and the image pickup tube beam current switching means 15.
It is set to C2 so that it will be input to . Here, the gain switching means 14 selects X#i! The amplification degree of the amplification means 9 is switched and controlled based on the exposure timing signal ζ2 sent from the exposure command device 16. Similarly, the image pickup tube beam current switching means 15 switches and controls the beam current of the image pickup tube 8 based on an exposure timing signal sent from the X-ray exposure command device 16.

Next, the detailed structure of the gain switching means 14 and the ten stages of image pickup tube beam flow switching 15 is shown in Figure 6c-2. The broken line 14 in the figure is a gain switching means for switching and controlling the gain (amplification degree) of the amplification means 9, and shows variable resistors 20c and 20d for setting the gain and these variable resistors 20c.

2 (Jcl) and a transistor 18b that drives the relay 19b. One end of the coil of the relay 19b is connected to a power supply circuit f2 (not shown), and a positive voltage (+V(!) is applied. Also X
The exposure timing (i
The voltage is applied to the transistor 18br via the base current limiting resistor 21b.

Here, variable resistor 20 is switched by relay 19b+2.
c and 20d are resistors for, for example, feed pins of the amplifying means 9, and by changing the total resistance value ≦2, the gain of the amplifying means 9 can be changed.

In addition, the broken line 15 in the figure is an image pickup tube beam current switching means.
f: Same as the gain switching means 14 described in iJ (2. Variable resistors 20a, 20b for beam current setting, L/-19b for switching the variable resistors 20a, 20b', and a transistor for driving the relay 19b) 18a. Here, a relay 19a (variable resistors 20a and 20b that can be switched from two to ) 16, for example, a part of the voltage dividing resistor (multiple resistors are connected together to cause a voltage drop in each resistor), and the value of this resistance is changed. Since the grating pressure of the tube 8 changes, the image pickup tube 8
beam current can be changed.

Next, the operation of the apparatus of this embodiment constructed as described above will be explained with reference to the timing chart of FIG. 4.

An exposure command timing signal T is sent from the X-ray exposure command device 16 to the X-ray control device 1. The gain switching means 14 and the image pickup tube beam current switching means 15 are operated by two people. For example, when this exposure timing command signal T is at a "high" level, the X-ray generator 2
is for high exposure, while the image pickup tube beam current switching means 15 changes C2 to increase the beam current Ib of the image pickup tube 8, and the gain switching means 14 changes C2 to decrease the gain G& of the amplification means 9.
It has two effects. Here, mI image pickup tube beam forming current conversion means 1
5 and the operation of the gain switching means 14 will be explained from FIG.

It is assumed that the resistance value of 20c is preset to a large value, for example. When the exposure timing signal T output from the X-ray exposure command device 13 is at a "low" level (TL at low exposure time),
Since transistors 18a and 18b are off, relays 19a and 19b do not operate. ' Then, as part of the voltage dividing resistor of the grid voltage setting means 16, for example, the variable resistor 20a (resistance value '
Likewise, a variable resistor 20C (set to a resistance value of "dog") is connected as a feedback resistor of the amplifying means 9 via the normally closed contact of the relay 19b. As a result, since the grating pressure of the image pickup tube 8 is low, the beam current of the image pickup tube 8 is small, and since the feedback leaf of the amplification means 9 is small, the gain of the amplification means 9 is high.

Next (when the exposure timing signal T output from the second X-ray exposure command device 16 is at the "high" level (high exposure time TH), the transistor 18a.

Since relay 18b is in the on state (because the base current flows through each resistor 218 and 21b), relay 19a
, 19b operate almost simultaneously (two settings). Therefore, as part of the voltage dividing resistor of the grid voltage setting means 16, the variable resistor 20b (resistance value "dog" (two settings)) is connected via the normally open contact of the relay 19a. Similarly, a variable resistor 20d (set to a "small" resistance value) is connected as a feedback resistor of the amplifying means 9 via the normally open contact of the relay 19b.As a result, the image pickup tube 8 Since the grating pressure becomes higher, the beam current of the image pickup tube 8 increases, and the feedback amount of the amplifying means 9 increases, so the gain of the amplifying means 9 decreases.

In this way, the beam current of the image pickup tube 8 and the gain of the amplifying means 9 are changed in accordance with the exposure command timing signal T output from the X-ray exposure command device u13 (in synchronization with the X-ray exposure C2). Image display by C2.

Image recording and image calculation processing, etc.C2 S of the video signal to be provided
/N ratio can be significantly improved. This will be theoretically proven below.

First, the video signal current ■s total ISH during high X-ray exposure
, if the image signal turtle current 1s at f2 at low exposure is ISL, then ISH” a・IbHl b・・・−・・−(4) IS
L2a ・II)H+b-...(5), and the video signal level V at the time of high X-ray exposure (2) is expressed as VH,
If the video signal level V at f2 during low exposure is VL, then Vrr = Gt, -ISH"""""'song (6)
vL2GH・isn・・・・・・・・・・・・ (
71, and furthermore, the S/N at high X-ray exposure (2
The ratio is S/N (Hl, S/N ratio k at low exposure time c S/
N (If Ll, it is expressed as follows. Here, for example, the video signal level V at the time of high exposure and the time of low exposure are set to the same level (the second amplification means 9
If the gain of is adjusted, then equation (6.) written in riiJ.

(7) In equation g2, VH” VL, so GL°l
It becomes 5H-GH+1SL ru. Next [2] Substituting this into the above equation (4) yields. In addition, WJ (4) formula (respectively refers to the people)
)formula.

Substituting into equation (9), we get: Therefore, during X-ray sieve exposure, the beam current of the image pickup tube is increased and at the same time the gain of the amplification means is decreased.
2. Therefore, a video signal with a high S/N ratio can be obtained.

Furthermore, since the video signal level obtained at this time with a high SIN ratio is almost equal to the video signal level with low exposure, T
Image observation on V monitor, image recording device d, and arithmetic processing device C2.

Image processing becomes easier (there is no need to adjust the level each time). Furthermore, since the beam current of the imaging tube is increased or decreased as necessary (increases only during exposure), it is possible to prevent the lifetime of the imaging tube from becoming low F.

This invention is not limited to the embodiments described in OjI,
It goes without saying that various modifications are included within the scope of the invention.

For example, the gain switching means 14 and the image pickup tube beam current switching means 15 in FIG. It is also possible to drive 19b, and if a two-circuit, two-contact relay is used, the number of relays can be reduced to one.

(2) The gain switching means 14 and image pickup tube beam current switching means 15 in FIG. A level change (FIG. 4 (al is shown only as a binary signal) is added to the X-ray exposure timing signal (a) output from C 13, and the beam of the image pickup tube 8 is adjusted according to this level change C2. The current and the gain of the amplification means 9 may be varied.An example thereof is shown in Fig. 5. Fig. 21a,
21b is an operational amplifier (hereinafter referred to as "OP amplifier"), the gain switching means 14 constitutes a so-called inverting amplifier circuit, and the image pickup tube beam current switching means 15 constitutes a so-called non-inverting amplifier circuit. There is. Resistors 22a and 23
OP amplifier 21a from the relationship between a and 22b and 23b.

The gain of 21b (resistor 26a in FIG. 4) is determined.

23be variable). With such a configuration (2), for example, a "high" level exposure timing signal is transmitted from the X-ray exposure command device 13 to the OP amplifier 21.
When the non-inverting input (+) of a and the inverting input of the OP amplifier 21b are applied to the inverting input of the OP amplifier 21b via the resistor 23b, a positive potential is applied from the output of the OP amplifier 21a to the grid voltage setting means 16+, while the OP amplifier A negative potential is applied to the output of the amplifying means 9 (two persons) from the output of the grid voltage setting means 16.
The beam current of the image pickup tube 8 is increased by increasing the lattice electric field EE of the image pickup tube based on the output of the OP amplifier 21a, and the gain of the amplification means 9 is decreased based on the output of the OP amplifier 21b. Here, since the OP amplifiers 211 and 21b are linear amplifiers, the beam current of the image pickup tube 8 and the gain of the amplification means 9 can be changed by 1α line g2 in accordance with the level change C2 of the exposure timing signal. Further, although the OP amplifiers 21a and 21be are each used as a non-inverting amplifier 2 and an inverting amplifier, they can be unified into either one according to the circuit configuration C2 of the grid pressure setting and determining means 16 and the amplifying means 9.

〔Effect of the invention〕

According to the present invention C2 described above, by changing the beam current of the image pickup tube and the gain of the amplification means in synchronization with the timing of X-ray exposure, the life of the image pickup tube is not shortened and the It is possible to provide an X-ray television apparatus that can process video signals of a high level and a high ratio, and thus can obtain accurate diagnostic information.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of the configuration of a conventional X-ray television device, FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention, and FIG. 6 is details of main blocks in the second factor. FIG. 4 is a timing chart for explaining the present invention, and FIG. 5 is a diagram showing a modification of FIG. 1...X-ray control device, 2...X-ray generator, ro...
・Subject, 4... Bed device, 5... Image indentifier, 6... Optical system, 7... X-ray television camera (TV camera), 8... Image pickup tube, 9.・・・
Amplifying means, 10... X-ray television monitor (TV monitor), 11... Image recording device, 12... Image calculation processing device, 16... X-ray exposure command device, 14... Gain Switching means, 15... Image pickup tube beam current switching means. Agent: Patent attorney Noriyuki Chika (and 1 other person) Figure 3

Claims (1)

[Claims] An X-ray television camera that captures an optical image obtained based on the X-rays C2 passing through the object and outputs a video signal; In an X-ray television apparatus for displaying H'J f=U2, an image pickup tube beam' (company) flow cutting means for controlling the beam current of an image pickup tube in an X-ray television camera, and a gain control means for controlling the gain of the amplification means. What is claimed is: 1. An X-ray television apparatus, characterized in that the imaging tube beam acid flow switching means and the gain switching means are operated in synchronization with the X-ray exposure timing.