JP2003173895A - X-ray tube control method and x-ray fluoroscopic inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray tube control method and an X-ray fluoroscopic inspection device obtaining an optimum transmission image by feeding back the transmission image of a specimen and automatically setting an X-ray condition. <P>SOLUTION: The X-ray fluoroscopic inspection device, having an X-ray tube and an X-ray detector detecting the X-ray transmitted through the specimen, forming a transmission image of the specimen depending on the transmission data obtained from the X-ray detector, is composed of an X-ray control part controlling voltage and current of the X-ray tube, an optimum condition estimation means estimating an optimum condition of either the voltage or the current of the X-ray tube which makes the lightness of prescribed two parts on the transmission image T1, T2 turn into aimed values T1aim, T2aim, and a setting means automatically setting the voltage and the current of the X-ray tube by repeatedly feeding the voltage and the current of the X-ray tube back to the X-ray control part according to the above optimum condition. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray fluoroscopic inspection apparatus for inspecting a subject by obtaining a transmission image of the subject using X-rays, and further, an X-ray suitable for obtaining an optimum transmission image. The present invention relates to a method of controlling a radio tube and an X-ray fluoroscopic inspection apparatus.

[0002]

2. Description of the Related Art In recent years, an X-ray fluoroscopic inspection apparatus for inspecting, for example, a small electronic component with high resolution has been provided on the market.

In such an X-ray fluoroscopic inspection apparatus, the tube voltage V and the tube current I of the X-ray tube can be manually changed, and the setting can be made according to the subject while observing the obtained transmission image of the subject. To obtain the optimum image.

Specifically, when the tube voltage is changed, the energy E of each X-ray photon is increased and the number N of photons is increased, and when the tube current is changed, 1 of the X-ray photons is changed. Each energy E remains unchanged and the number of photons N
Will increase.

The detector detects X-rays with a two-dimensional resolution, and the output of each detection element is proportional to the total amount of X-ray energy (E × N) received by each element. Then, a transmission image is formed by appropriately setting a threshold value and assigning lightness and darkness according to the output of each detection element. On the other hand, the X-ray transmission capability increases as the energy E of each X-ray photon increases.

When manually changing the tube voltage V and the tube current I, the tube voltage V (that is, X
The energy E) of each line photon is selected, but if the energy E is too high, the contrast of the image is reduced and the best image is not obtained. Therefore, the tube voltage V is lowered and the tube current I is increased to supplement the output. However, if the tube voltage V is lowered too much, the contrast becomes too large, resulting in an overexposed or blackened image.

As described above, the conventional X-ray condition setting is very troublesome because the tube voltage V and the tube current I are manually set alternately every time the subject is exchanged or the observation visual field is changed. Moreover, there is a possibility that the obtained image quality will depend on the skill of the operator.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and an object of the present invention is to feed back a transmission image of a subject and automatically set X-ray conditions to obtain an optimum transmission image. An object of the present invention is to provide an X-ray tube control method and an X-ray fluoroscopic inspection apparatus to be obtained.

[0009]

In order to achieve the above-mentioned object, the invention according to claim 1 of the present invention controls an X-ray tube and a tube voltage and a tube current of the X-ray tube. An X-ray fluoroscope having an X-ray controller and an X-ray detector for detecting X-rays transmitted through the subject, and creating a transmission image of the subject from transmission data of the subject obtained by the X-ray detector. X in inspection equipment
A method for controlling a tube, comprising estimating an optimum condition of at least one of a tube voltage and a tube current such that the brightness of the two parts on the transmission image reaches a predetermined target value, and the estimation is performed. The gist of the present invention is that the tube voltage and the tube current are repeatedly fed back to the X-ray control unit according to the optimized conditions, and the tube voltage and the tube current are automatically set.

According to the first aspect of the present invention, the transmission image of the subject is fed back to automatically set the X-ray condition, and the optimum transmission image can be obtained. Further, since the correction values of the tube voltage and the tube current in one loop of feedback are obtained by the optimal estimation, the convergence can be speeded up.

The invention according to claim 2 of the present invention has an X-ray tube and an X-ray detector for detecting X-rays transmitted through an object, and is obtained by this X-ray detector. An X-ray fluoroscopic inspection apparatus for creating a transmission image of a subject from the transmission data of the subject, comprising: an X-ray control unit for controlling a tube voltage and a tube current of the X-ray tube; and a predetermined unit on the transmission image. The brightness T1 and T2 of the two parts are respectively set to predetermined target values T1ai.
m, T2aim, an optimum condition estimating means for estimating at least one of the optimum conditions of the tube voltage and the tube current, and the tube voltage and the tube current are repeatedly fed back to the X-ray controller according to the estimated optimum conditions. The gist is to have setting means for automatically setting the tube voltage and the tube current.

According to the second aspect of the present invention, the transmission image of the subject is fed back to automatically set the X-ray condition, and the optimum transmission image can be obtained. Further, since the correction values of the tube voltage and the tube current in one loop of feedback are obtained by the optimal estimation, the convergence can be speeded up.

According to the third aspect of the present invention, the X-ray tube, the X-ray control unit for controlling the tube voltage and the tube current of the X-ray tube, and the X-ray transmitted through the subject. A method for controlling an X-ray tube in an X-ray fluoroscopic inspection apparatus, comprising: an X-ray detector for detecting an object, and creating a transmission image of the object from transmission data of the object obtained by the X-ray detector, The optimum condition of the tube voltage at which the brightness of one portion on the transmission image becomes a predetermined target value and the maximum allowable tube current is estimated, and the estimated tube voltage and tube current are used as the X-rays. The gist is to automatically set the tube voltage and the tube current by repeatedly feeding back to the control unit.

According to the third aspect of the present invention, the transmission image of the subject is fed back to automatically set the X-ray condition, and the optimum transmission image can be obtained. Further, since the correction values of the tube voltage and the tube current in one loop of feedback are obtained by the optimal estimation, the convergence can be speeded up.

Furthermore, the invention according to claim 4 of the present invention has an X-ray tube and an X-ray detector for detecting X-rays transmitted through an object, and is obtained by this X-ray detector. An X-ray fluoroscopic inspection apparatus for creating a transmission image of a subject from the transmission data of the subject, wherein X controls the tube voltage and tube current of the X-ray tube.
A line controller, and an optimum condition estimating means for estimating an optimum condition of the tube voltage at which the brightness T1 of one portion on the transmission image becomes a predetermined target value T1aim and the maximum tube current is allowed. , Estimated tube voltage and tube current are
The gist is to have a setting means for automatically setting the tube voltage and the tube current by repeatedly feeding back to the line control section.

According to the fourth aspect of the present invention, the transmission image of the subject is fed back to automatically set the X-ray condition, and the optimum transmission image can be obtained. Further, since the correction values of the tube voltage and the tube current in one loop of feedback are obtained by the optimal estimation, the convergence can be speeded up.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of an X-ray fluoroscopic inspection apparatus to which the X-ray tube control method of the present invention is applied.

The system configuration itself shown in FIG. 1 is almost the same as the conventional device in terms of hardware. The X-ray tube 1 of this embodiment uses a microfocus X-ray tube having a focal point F of generated X-rays of several to several tens of μm. In addition, the detector includes an X-ray I.V. that converts an X-ray image transmitted through the subject into an optical image.
I. (Image Intensifier) 3 and the X-ray I.D. I. The television camera 4 for capturing the optical image obtained in 3 is used.

The subject 5 is placed on the sample table 6 and positioned in the X-axis and Y-axis directions within the X-ray beam 2, and the XY mechanism 7 changes the field of photography (observation). X-ray tube 1
Is moved up and down by an elevating mechanism (not shown) so that the photographing magnification can be changed.

The personal computer 8 takes in a transmission image of the subject from the television camera 4, estimates the tube voltage V and the tube current I of the X-ray tube 1 that optimize this image by an optimum condition estimation program, and further estimates these estimated values. To the X-ray controller 9. X
The line controller 9 adjusts the tube voltage V and the tube current I of the X-ray tube 1 to the estimated values through the high voltage generator 10 based on the estimated values.
This is one loop of feedback. Actually, there is an estimation error, so by repeating this, it is possible to quickly adjust to the optimum value. The estimation of the optimum V and I is performed by software installed in a memory (not shown) of the personal computer 8.

The tube voltage V and the tube current I have a range limited by the X-ray controller 9. This is determined by the heat limitation of the target of the X-ray tube 1 and the capacity of the high-pressure generating section. It is also possible to separately set a limit range for optimum control within this range.

For example, in the case of a microfocus X-ray tube, if the current is too large, the focus may become large, so the tube current is limited to a small value.

Next, the operation of this embodiment will be described.

Here, the personal computer 8 in this embodiment is used.
The estimation function of the optimum condition (V, I) will be described.

FIG. 2 shows the X-ray condition automatic setting mode.
In the figure, the vertical axis represents the brightness B of the image on the linear scale, that is, a value proportional to the output of the detector, and the horizontal axes represent modes 1, 2, to 6 ,. The brightness B is 0 to the saturation value Bsa
t (255), Bobs. l (80) to Bo
bs. Values up to h (180) are suitable for observation. In such an operating environment, the operator of the fluoroscopic examination apparatus selects one mode. The modes are: Mode 1: All observation Mode 2: Dark part observation (saturation not allowed) Mode 3: Specified part 1 point observation (saturation not allowed) Mode 4: Specified part 2 point observation (saturation allowed) Mode 5: Bright part observation Mode 6: There are 6 modes of 1 point observation (saturation permission) of the designated area.

In the mode 1, the brightest portion B1 and the darkest portion B2 are Bobs. h and Bobs. V and I are controlled to match l. Here, B1 and B2 are the maximum and minimum averaged for each of the predetermined (grid-like) sections. Here, all parts (unless the restrictions of V and I are imposed) have the brightness suitable for observation.

In mode 2, the bright portion B1 is Bh before saturation.
In the dark area B2, Bobs. It is controlled so as to meet l, and it is a good condition for observing dark areas under the condition that it is not saturated.

In mode 3, the bright area B1 is Bh before saturation.
In addition, the brightness B3 of one point (actually, the average of the small areas) in which the operator designates the ROI as the ROI is Bobs. It is controlled so as to meet l, and it is a good condition for observing the designated part under the condition that it is not saturated.

In mode 4, the operator designates the ROI as 2
The brightness of points B3 and B4 is Bobs. h and Bob
s. It is controlled so as to meet l, which is a good condition for observation between two points on the designated portion.

In mode 5, the bright portion B1 is Bobs. The tube voltage V is controlled to be as small as possible and the tube current I is set to be as large as possible so that the contrast in the bright portion is good and the noise is small.

In mode 6, the brightness B1 at one point designated by the operator as the ROI is Bobs. h and Bobs. B in the middle of l
tube voltage V as small as possible and tube current I
Is controlled so as to be large, so that the contrast of the designated portion is good and there is little noise.

In the following description, the logarithmically converted brightness T is used.

T = Log (B) (1) Modes 1 to 4 are basically the same optimal estimation process, and the brightness T1 and T2 of the two parts are respectively set to predetermined target values T1aim and T2aim. It is a matching control and can be said to be "two-point optimization" control. As will be described later, T1 and T2 are replaced by T1aim and T2a, respectively.
V and I are uniquely determined from the condition that matches with im. This is,
It is an estimated value of optimum V and I.

The modes 5 and 6 are basically the same optimum estimation process, and the brightness T1 of one portion is set to a predetermined target value T1.
Adjust to 1 aim and increase the tube voltage I as much as possible,
The control for reducing the tube voltage V can be called "one-point optimization" control. When the energy E of each X-ray photon is N and the number of photons N, the image brightness B is proportional to E × N. If E × N is the same, the photon noise is reduced by decreasing the energy E and increasing the photon number N as much as possible. Therefore, the tube current I is increased as much as possible and the tube voltage V is increased.
To reduce.

<Control of “Optimization between Two Points”> FIG. 3 is a flow chart of V and I control in the present embodiment, FIG. 4 is a relation between detector output and control loop, and FIG. 5 is tube current / tube. 3 shows the relationship between voltage and control loop.

First, the control of "optimization between two points" will be described.

Hereinafter, logarithmically converted V and I will be used.

X = Log (V / V0) (2) Y = Log (I / I0) (3) As shown in FIGS. 4 and 5, A is the previous position on the XY plane,
Let B be the current position and C be the next position. The XY position of each point is represented by suffixes A, B, and C, respectively. The brightnesses T1, T2 of the two parts at the respective positions A, B, C are represented by suffixes A, B, C, respectively.

Each step will be described below.

S11: Initialize X _B and Y _B.

S13: The process ends when the automatic end is input (YES), otherwise (NO) the step S1.
Go to 5.

S15: Tube voltage V and tube current I are respectively X
Change to _B , Y _B.

S17: The transmission image is collected after the tube voltage V and the tube current I have converged.

S19: Average brightness T1 _B of the two parts,
Calculate T2 _B.

S21: Previous value (X_A, Y_A, T1_A, T
Two_A) And the current value (X_B, Y_B, T1 _B, T2_B) From 2
Estimate the average transmission lengths t1 and t2 of the two parts.

S23: Current value (X_B, Y_B, T1_B, T
Two_B) And t1 and t2, the next value (X _C, Y_C)
It

S25: Previous value (X_A, Y_A, T1_A, T
Two_A) Is the current value (X_B, Y_B, T1 _B, T2_B) Put
Instead, the current value (X_B, Y_B) Is the next value (X_C, Y_C)so
After the replacement, the process returns to step S13.

That is, the optimum tube voltage V and the tube current I are estimated in steps S21 and S23 which constitute the optimum condition estimating unit, and the tube voltage V and the tube current I of the X-ray tube 1 are adjusted to the estimated values in step S15. . Actually, there is an estimation error, so by repeating this, it is possible to quickly adjust to the optimum value.

Before describing the optimum condition estimation unit, the basic formula used in the processing procedure will be described. First, the V and I dependence of the brightness B on the linear scale is roughly expressed by the following equation.

[0051]

## EQU1 ## B = B0.I / I0. (V / V0) ^ke.exp (-. Mu. (V) .t) (4) where .mu. Is an absorption coefficient, t is a transmission length, and ke is 2 to 2. It is a constant of 0.5. This is logarithmically transformed to formulas (1), (2),
Using (3),

[Equation 2] T = T0 + Y + ke · X−μ (X) · t (5) Although μ (X) varies depending on the substance, an average value is used by approximation with an empirical formula. With this as a basic equation, the following equation for estimating the transmission length t can be derived.

[0052]

## EQU00003 ## t = (. DELTA.Y-.DELTA.T + ke.DELTA.X) /. DELTA..mu. (6) where each .DELTA. Is the amount of change when X and Y are changed.

FIG. 6 is a diagram showing details of the optimum condition estimating unit.
It In step S21A, the average transmission length is calculated according to equation (6).
Estimate t1 and average transmission length t2. The detailed description here
No, but the previous value of X_AAnd the current value of X_BDifference is too small
Error will be large, so t1 and t2 are not calculated.
Uses the round value. In step S23A, the next value (X_C，
Y _C) Is estimated. Replace T1 and T2 with T1aim and T2ai
X under the condition of adjusting to m_C, Y_CUniquely solve for
To be

[0054]

[Equation 4] Or

Equation 5] _{Y C = Y B + T2aim-} T2 B -ke · (X C -X B) + (μ-μ (X B)) becomes · t2 ... (9 '). Here, the function X (μ) can be predetermined as an inverse function of μ (X).

FIG. 7 and FIG. 8 are explanatory views of the optimum condition estimation.
It With reference to this figure, basic equation (5) to equation (7)-
The outline of the derivation of (9 ') will be described. Where B is this time
Position C is the next position. From point B to T1aim-T1 _B
At the point B1 which has risen only by 1, T1 coincides with T1aim.
From point B to T2aim-T2_BIncrease (-value decreases)
At point B2, T2 coincides with T2aim. Through point B1
Curve 1 where T1 is constant starts from basic equation (5)
do it,     T = T0 + Y + ke · X−μ (X) · t (5)     Y = T−T0−ke · X + μ (X) · t (21) The formula for curve 1 is

[Equation 6]     Y = T1aim-T0-ke * X + [mu] (X) * t1 (22) At point B

[Equation 7] Y _B = T1 _B −T0−ke · X _B + μ (X _B ) · t1 (23) When the difference between equations (22) and (23) is calculated and T0 is deleted, the equation of curve 1 is obtained. Is

Equation 8] is revealed by _{Y = Y B + T1aim-T1} B -ke · (X-X B) + (μ (X) -μ (X B)) · t1 ... (10).

For curve 2 where T2 is constant through point B2,

[Equation 9]     Y = T2aim-T0-ke * X + [mu] (X) * t2 (24) At point B

Equation 10] and obtains a difference _{Y B = T2 B -T0-ke} · X B + μ (X B) · t2 ... (25) equation (24) and (25), clearing the T0, the curve 2 ceremony,

Equation 11] is revealed by _{Y = Y B + T2aim-T2} B -ke · (X-X B) + (μ (X) -μ (X B)) · t2 ... (11). From the difference between equations (23) and (25),

[Equation 12]     (T2-t1) = (T1_B-T2_B) / Μ (X_B)… (12) Can lead. Equation (11) is subtracted from Equation (10) to obtain Equation (1
2) is used to eliminate t1 and t2 and solve for μ (X)
Equation (7) is obtained. Further, in the formula (8), the next value X _CTo
Obtained and substituted for X in equations (10) and (11), equation (9),
(9 ') can be obtained.

That is, it is as follows.

Here, the coordinates of the intersection C are obtained.

[0059]

[Equation 13] From the difference between equations (23) and (25)

[Equation 14] T1 _B −T2 _B −μ (X _B ) · (t2 −t1) = 0 (t2 −t1) = (T1 _B −T2 _B ) / μ (X _B ) ... (12)

[0060]

[Equation 15] Μ is calculated by the equation (7) (μ = μ (X)).

Next, X _C is obtained by X _C = X (μ) (8), and μ and X _C are substituted into the equation (10) or (11) to obtain Y _C.

[0062]

Equation 16] _{Y C = Y B + T1aim-} T1 B -ke · (X C -X B) + (μ-μ (X B)) · t1 ... (9) Y C = Y B + T2aim-T2 B -ke _{· (X C -X B) +} (μ-μ (X B)) · t2 ... (9') in estimation calculation schematically shown in FIG. 6, the next position C exceeds the limits of the current-voltage Cases are omitted. For example, when the point C exceeds the current upper limit or the voltage lower limit in FIGS. 7 and 8, the limit point C1 along the curve 1 or the limit point C2 along the curve 2 is selected.

In the case where the heights of the points B1 and B2 are reversed, the point C can be located at the lower right of the point B, and the point C may exceed the current lower limit or the voltage upper limit, but similarly the point C1 or the point C2. Select. Specifically, for example, in the case of mode 2,
If the voltage is decreasing, C2 is used. If the voltage is increasing, C2 is used.
Select 1.

<Control of "One-Point Optimization"> Next, the control of "one-point optimization" will be described.

The entire flow chart of V and I control is shown in FIG.
Similar, but T2_B, T2, T2 _AIs calculation-free
It

FIG. 9 shows an optimum condition estimating unit. Step S
In 21B, t1 is estimated according to the equation (6) as in “optimization between two points”. In step S23B, the next value (X _C , Y
Estimate _C ). X is started from X _B and Y is calculated by the equation (10) while changing downward in minute steps, and the limit points of the voltage and current limits are obtained and set as X _C and Y _C. Since the expression (10) is the curve 1 (see FIG. 8) in which V1 changes while keeping T1 at T1aim as described above, T1 is set to the target value T1ai.
Optimal estimation is performed so that the tube current I is as large as possible and the tube voltage V is as small as possible.

Next, the effect of this embodiment will be described.

According to the first embodiment, it is possible to feed back the transmission image of the subject and automatically set the X-ray condition to obtain the optimum transmission image. Further feedback 1
Since the corrected values of V and I in the loop are obtained by the optimum estimation, the convergence can be speeded up.

In the X-ray fluoroscopic inspection apparatus having the configuration as shown in FIG. 1, a personal computer 8 which normally processes a transmission image and a unique CP are used.
Since the communication time with the X-ray control unit 9 operating in U and the response time of the X-ray tube control from the X-ray control unit 9 are long, one feedback loop time cannot be shortened. Even in such a case, according to the present embodiment, the correction can be made at a high speed so that the correction can be made to match the optimum value at one time.

As a result, the optimum transmission image can be easily obtained without depending on the skill of the operator, and the optimum transmission image can be obtained in real time by changing the observation field of view or the image magnification. In addition, it can support various cases by changing the mode.

Next, a modification of this embodiment will be described.

Although the brightness T1 and T2 are described as the simplest method of averaging predetermined sections or averaging the ROI-designated portions, the present invention is not limited to this. For example, it is possible to decide by performing various image processing. For example, a histogram of the brightness of the whole or ROI is taken, and the 80% position of the histogram area is T
The "two-point optimization" control may be performed with the 1 and 20% positions as T2, and the "one-point optimization" control may be performed with the 50% position as T1. It is also conceivable to estimate a portion of interest by image processing and average this portion to obtain T1.

Such X-ray tube control is performed by the X according to the present invention.
Since the X-ray tube control program is realized by the X-ray tube control program and the program is recorded in a recording medium and provided, the distribution of the X-ray tube control program can be enhanced by using the recording medium.

In the above embodiment, the case where the invention is applied to the X-ray fluoroscopic inspection apparatus has been described as an example. However, the present invention is not limited to this, and any image utilizing an X-ray exposure can be used. Can be applied to the device.

[0075]

As described above, according to the present invention, since the tube voltage / tube current obtained from the transmission image of the subject is fed back to automatically set the X-ray condition, it is easy to perform. X that can quickly and optimally obtain an optimum transmission image
An X-ray fluoroscopic inspection apparatus and a control method of a X-ray tube can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic system configuration of an embodiment of an X-ray transmission inspection apparatus according to the present invention.

FIG. 2 is a diagram showing a mode of X-ray condition automatic setting in the X-ray transmission inspection apparatus shown in FIG.

FIG. 3 is a flowchart schematically showing the flow of V and I control.

FIG. 4 is a diagram showing a relationship between a detector output and a control loop.

FIG. 5 is a diagram showing a relationship between a tube current / tube voltage and a control loop.

FIG. 6 is a flowchart schematically showing the flow of processing in an optimum condition estimation unit (optimization between two points).

FIG. 7 is a diagram for explaining optimal condition estimation (optimization between two points).

FIG. 8 is a diagram for explaining optimal condition estimation (optimization between two points).

FIG. 9 is a flowchart schematically showing the flow of processing in an optimum condition estimation unit (one-point optimization).

[Explanation of symbols]

1 X-ray tube 2 X-ray beam 3 X-ray I.D. I 4 TV camera 5 subject 6 sample table 7 XY mechanism 8 PC 9 X-ray controller 10 High voltage generator F focus

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G21K 5/02 G21K 5/02 X (72) Inventor Tatsuyuki Yoshihara 2-24 Harumicho, Fuchu-shi, Tokyo No. 1 TOSHIBA IT Control System Co., Ltd. (72) Inventor ▲ Tsuru ▼ Shoji No. 1 2-24 Harumicho, Fuchu-shi, Tokyo TOSHIBA IT Control System Co., Ltd. F-term (reference) 2G001 AA01 BA11 CA01 GA09 GA11 HA13 JA02 JA20 LA11 2H013 AB10 4C092 AA00 AB02 AB04 AC08 AC16 CC03 CD02 CD03 CF02 CF07 CF08

Claims (4)

[Claims] 1. An X-ray tube, an X-ray controller for controlling a tube voltage and a tube current of the X-ray tube, and an X-ray detector for detecting an X-ray transmitted through an object. An X-ray tube control method in an X-ray fluoroscopic inspection apparatus that creates a transmission image of a subject from transmission data of the subject obtained by a line detector, wherein the brightness of two parts on the transmission image is An optimum condition of at least one of the tube voltage and the tube current is estimated so that the target value becomes a predetermined value, and the tube voltage and the tube current are repeatedly fed back to the X-ray controller according to the estimated optimum condition. An X-ray tube control method characterized by automatically setting a voltage and a tube current. 2. An X-ray tube and an X-ray detector for detecting X-rays transmitted through the subject, and a transmission image of the subject is obtained from transmission data of the subject obtained by the X-ray detector. An X-ray fluoroscopic inspection apparatus to be created, comprising: an X-ray control unit for controlling a tube voltage and a tube current of the X-ray tube; and brightness T1, of predetermined two parts on the transmission image.
T2 is a predetermined target value T1aim, T2a, respectively.
an optimum condition estimating means for estimating at least one of the optimum conditions of the tube voltage and the tube current so as to be im, and the tube voltage and the tube current are repeatedly fed back to the X-ray control unit in accordance with the estimated optimum conditions. An X-ray fluoroscopic inspection apparatus having a setting means for automatically setting a tube voltage and a tube current. 3. An X-ray tube, an X-ray controller for controlling a tube voltage and a tube current of the X-ray tube, and an X-ray detector for detecting an X-ray transmitted through an object. A method for controlling an X-ray tube in an X-ray fluoroscopic inspection apparatus that creates a transmission image of a subject from transmission data of the subject obtained by a line detector, wherein the brightness of one portion on the transmission image is predetermined. The optimum condition of the tube voltage that becomes the target value and the maximum allowable tube current is estimated, and the estimated tube voltage and tube current are repeatedly fed back to the X-ray controller to obtain the tube voltage and tube current. An X-ray tube control method characterized by automatic setting. 4. An X-ray tube and an X-ray detector for detecting X-rays transmitted through the subject, and a transmission image of the subject is obtained from transmission data of the subject obtained by the X-ray detector. An X-ray fluoroscopic inspection apparatus to be created, comprising: an X-ray control unit for controlling a tube voltage and a tube current of the X-ray tube; and a target value T1aim for which a brightness T1 of one portion on the transmission image is predetermined. And an optimum condition estimating means for estimating the optimum condition of the tube voltage that is the maximum allowable tube current, and the estimated tube voltage and tube current are repeatedly fed back to the X-ray control unit to make the tube voltage and the tube current. And a setting means for automatically setting the X-ray fluoroscopic inspection apparatus.