JP2001212120A - X-ray control device and X-ray imaging device - Google Patents

Abstract

(57) [Summary] [Problem] Even when performing X-ray imaging for various uses,
Provided are an X-ray control device capable of obtaining a fluoroscopic image suitable for diagnosis, and an X-ray imaging device using the control device. A tube voltage generation unit inputs a tube voltage information for compensating for excessive or insufficient luminance of an X-ray fluoroscopic image from a camera control unit, and when the luminance is less than a desired luminance, increases a tube voltage. The CPU 1a determines a tube current in accordance with a preset tube voltage-tube current relationship below the newly set tube voltage, sets the tube current in the tube current creation unit 1c, and sets the tube current creation unit 1c.
c is such that the tube current of the X-ray tube 3 becomes the determined tube current. If the newly set tube voltage exceeds the allowable range, the CPU 1a determines the tube current so that the tube voltage falls within the allowable range, and sets the tube current in the tube current creation unit 1c. When the determined tube current further exceeds the allowable range of the tube current, the CPU 1a controls the iris 8 to be widened through the iris control unit 1e.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray control device for controlling a tube voltage supplied to an X-ray tube, and an X-ray imaging apparatus provided with the X-ray control device.

[0002]

2. Description of the Related Art An X-ray photographing apparatus which irradiates a subject with X-rays and takes a transmission image thereof is widely used for diagnosis of a lesion. In such an X-ray imaging apparatus, the quality, intensity, and dose of X-rays applied to a subject greatly affect the image quality of a captured image, and particularly when a fluoroscopic image of the digestive system or angiographic blood vessels in the abdomen is obtained. X-ray irradiation conditions such as tube voltage and tube current are very important factors in obtaining a fluoroscopic image suitable for diagnosing a lesion.

[0003] It is known that the relationship between the tube voltage and the tube current is generally suitable in accordance with the region to be imaged and the purpose of diagnosis. Therefore, the setting of the relationship between the tube voltage and the tube current is suitable for such conditions. In addition to adjusting the iris of the fire, it is usually performed appropriately at the time of installation of the X-ray imaging apparatus in accordance with the frequently used application for each use facility.

[0004]

However, when it is necessary to use the X-ray imaging apparatus having such a configuration for a variety of applications, a tube voltage suitable for the part to be viewed is permitted depending on the part to be viewed. The range may be significantly different. In such a case, since imaging must be performed with an allowable tube voltage and a corresponding tube current, a desired X-ray quality cannot be obtained, and a fluoroscopic image suitable for diagnosis may not be obtained.

Accordingly, the present invention has been made to solve such a problem, and is capable of obtaining a fluoroscopic image suitable for diagnosis even when performing X-ray photography for various uses. An object of the present invention is to provide an X-ray imaging apparatus using the X-ray control device and the X-ray control device.

[0006]

According to the first aspect of the present invention,
In an X-ray control device that controls an X-ray tube so as to obtain an X-ray fluoroscopic image having a desired luminance, a tube voltage for obtaining a desired luminance is determined based on luminance information of the X-ray fluoroscopic image, and the tube voltage is set to the same tube voltage. A tube voltage control means for controlling the X-ray tube; and a tube current corresponding to the determined tube voltage determined from a tube voltage-tube current relationship set in advance.
In addition to controlling the tube, when the determined tube voltage is out of the allowable range, the tube current is determined so that the difference from the allowable upper limit value or lower limit value is zero, and X is set so that the tube current becomes the same. Tube current control means for controlling the line tube.

According to the X-ray control device of the first aspect,
If the tube voltage set to obtain the desired luminance for the fluoroscopic image is out of the allowable range, the tube current acting so that the difference between the same tube voltage and the upper limit or lower limit of the allowable range becomes zero. It is determined and the X-ray tube is controlled to have the same tube current. Thereby, the tube current of the X-ray tube is adjusted so that an X-ray fluoroscopic image having a desired luminance can be obtained while the tube voltage is kept at the upper limit value or the lower limit value of the allowable range.

[0008] The X-ray controller according to the second aspect is the first aspect.
In the X-ray control device described in the above, further, even if the determined tube current is out of the allowable range, the X-ray detection is performed so that the difference between the tube voltage and the allowable upper limit or lower limit is zero. An iris control means for changing and controlling the iris opening of the section.

According to the X-ray control device of the second aspect,
When the tube voltage and the tube current value adjusted to obtain the desired luminance for the fluoroscopic image are out of the respective allowable ranges, the iris opening is adjusted so that the tube voltage approaches the upper limit or the lower limit of the allowable range. Controlled. This makes it possible to obtain an X-ray fluoroscopic image having a desired luminance by adjusting the aperture of the iris in a state where both the tube current and the tube voltage are held near their upper and lower limits.

According to a third aspect of the present invention, there is provided an X-ray imaging apparatus, wherein the X-ray tube, an X-ray detecting unit comprising an image intensifier, an iris, and a camera, and the first or second aspect.
An X-ray control device as described above is provided.

According to the third aspect of the present invention, when the tube voltage is out of the allowable range, the tube current is separately adjusted,
Further, when the tube current is out of the allowable range, the aperture of the iris can be adjusted, so that a good X-ray fluoroscopic image having a desired luminance can be obtained even when used for a variety of applications. Becomes possible.

[0012]

FIG. 1 is a diagram showing a schematic configuration of an X-ray control apparatus 1 and an X-ray imaging apparatus according to an embodiment of the present invention. In FIG. 1, an X-ray control device 1 controls a tube voltage and a tube current in the X-ray tube 3 and controls an aperture of an iris 8 based on an imaging condition instructed by an operation panel 2.

The X-ray controller 1 controls various operations.
PU 1a, memory 1b for storing the allowable range of the tube voltage and the tube current, and the relationship between the tube voltage and the tube current shown in FIG. 2, a tube current creation unit 1c for creating and controlling the tube current of the X-ray tube 3, an X-ray tube 3
And an iris control unit 1e that controls the opening of the iris 8.

The tube current generator 1c controls the X-ray tube 3 so that the tube current of the X-ray tube 3 becomes the tube current set by the CPU 1a.
The filament current of the tube 3 is controlled. Specifically, as shown in the following equation, the actual tube current value Ar input from the X-ray tube 3 and the set tube current Ad set by the CPU 1a.
Filament current Fr that works so that the difference from
The X-ray tube 3 is controlled so as to flow. Fr = α (Ad−Ar) + Fr (1) α: proportionality constant

The tube voltage generator 1d receives a voltage signal Vl indicating a shortage of luminance from the camera controller 10, and adds the voltage signal Vl to the current actual tube voltage Vr so as to obtain a new tube voltage Vr. 3 is controlled. In addition, the tube voltage generation unit 1d
The actual tube voltage Vr is output to PU1a.

When the actual tube voltage Vr output from the tube voltage generator 1d is within the allowable range, the CPU 1a responds to the tube current generator 1c based on the tube voltage-tube current relationship shown in FIG. When the tube current is set in the tube current creation unit 1c and the actual tube voltage Vr is out of the allowable range, a new set tube current that works so that the actual tube voltage Vr falls within the allowable range is expressed by the following equation. Ad is determined and set in the tube current creation unit 1c. When exceeding the upper limit: Ad = β (Vr−VuL) + Ad (2-1) When falling below the lower limit: Ad = β (Vr−VdL) + Ad (2-2) VuL: allowable Upper limit of range VdL: Lower limit of allowable range β: Proportional constant

Further, when the determined tube current Ad does not fall within the allowable range of the tube current, the CPU 1a does not newly set the tube current, or sets the upper limit AuL or the lower limit AdL to the tube current generator 1c. , And the opening Opd of the iris 8 that works so that the actual tube voltage Vr falls within the allowable range is determined as shown in the following equation, and the iris 8 is controlled via the iris control unit 1e so as to be in this opening. . Exceeding the upper limit: OPd = γ (Vr−VuL) + OPd (3-1) Exceeding the lower limit: OPd = γ (Vr−VdL) + OPd (3-2) γ: proportional constant

The X-ray tube 3 irradiates the subject 4 placed on the table 5 with X-rays under the tube current and tube voltage controlled by the tube current generator 1c and the tube voltage generator 1d. . The transmitted X-ray transmitted through the subject 4 is converted into an optical signal by an image intensifier 6, condensed by an optical system 7, and then enters a camera 9 at an iris 8 whose opening size is variable. The light quantity is adjusted. The X-ray fluoroscopic image of the subject 4 detected by the camera 9 is
The image is displayed on the monitor 11 via the camera control unit 10.
Further, the camera control unit 10 detects the luminance of the X-ray fluoroscopic image and determines a voltage value considered to compensate for the insufficient luminance based on the difference from the standard value based on the graph showing the insufficient luminance and the insufficient voltage shown in FIG. Then, the output is output to the tube voltage generator 1d.

Next, the operation of the present invention in the case where the luminance of the X-ray fluoroscopic image is excessive or insufficient will be described with reference to FIG.
A description will be given based on the flowchart of FIG. First, for example, when limb shaping is selected as the imaging region on the operation panel 2, the CPU 1a issues an allowable upper limit value VuL and a lower limit value VdL of the tube voltage, an allowable upper limit value AuL and a lower limit value AdL of the tube current from the operation panel 2. Figure 2 suitable for imaging of limb shaping
Is input and stored in the memory 1b (S1).

Next, as an initial setting, the CPU 1a
The initial tube voltage Vb and the initial tube current Ab at are set in the tube voltage generator 1d and the tube current generator 1c, respectively (S
2) After that, the actual tube voltage Vr is input from the tube voltage generator 1d (S3). The CPU 1a calculates the input actual tube voltage Vr.
Is compared with the upper limit value VuL and the lower limit value VdL of the allowable range (S4). If the current value is within the allowable range, the tube current Ad corresponding to the actual tube voltage Vr is determined based on the graph of FIG. The setting is performed for the unit 1c (S5).

In this state, X-ray fluoroscopy is continuously performed, and the camera control unit 10 controls the subject 4 obtained from the image intensifier 6 via the camera 9.
Is extracted, and if the desired luminance is not obtained, the insufficient luminance is converted into the corresponding undervoltage Vl using the graph shown in FIG. , The actual tube voltage Vr changes every moment to compensate for the lack of luminance. The luminance of the fluoroscopic X-ray image can be obtained by a known method from the average luminance value and peak value of the image for one frame.

In this way, when the real tube voltage Vr changed every moment exceeds the upper limit value VuL of the allowable range, CP
U1a calculates the tube current Ad acting to make the difference between the allowable upper limit value VuL and the actual tube voltage Vr zero based on the above-mentioned equation (2-1) based on the current tube current Ad: Ad = β (Vr−VuL) ) + Ad (2-1) is obtained (S6). If the determined tube current Ad does not exceed the upper limit AuL of the allowable range (S7), the tube current Ad is set in the tube current generator 1c (S8), and the actual tube current Ad is set to the allowable upper limit AuL. These operations are repeated within a range not exceeding (S6, S7, S8).

As a result, according to the equation (2-1), the tube current increases in proportion to the difference between the allowable upper limit value VuL and the actual tube voltage Vr, whereby the luminance detected by the camera control unit 10 is reduced. The tube current increases and finally the tube current set at the time when the actual tube voltage Vr reaches the upper limit value VuL is stabilized.

Therefore, when the tube current Ad does not exceed the allowable tube current AuL, the actual tube voltage Vr is changed to the upper limit value VuL of the allowable range.
In this state, the tube current is adjusted separately from the tube voltage-tube current relationship shown in FIG.
A fluoroscopic image can be obtained.

Next, as a result of obtaining a tube current Ad acting to make the difference between the allowable upper limit value VuL and the actual tube voltage Vr zero, if the tube current Ad does not fall within the allowable upper limit value AuL,
If the actual tube voltage Vr does not fall to the allowable upper limit value VuL even if the tube current is raised to the upper limit AuL of the allowable range, C
PU1a sends the allowable upper limit value AuL to the tube voltage generator 1c.
Is set (S7, S9). Then, based on the current opening OPd of the iris 8, the new opening OPd of the iris 8 acting so that the difference between the actual tube voltage Vr and the allowable upper limit value VuL becomes zero is calculated by the above equation (3-1), that is, OPd = Γ (Vr−VuL) + OPd (3-1), and the iris control unit 1 is set to have this opening.
The iris 8 is controlled via e (S10).

These operations are repeated until the actual tube voltage Vr falls below the allowable upper limit value VuL (S11, S1).
0). As a result, since the X-ray fluoroscopic image can further obtain luminance, the luminance detected by the camera control unit 10 further approaches the reference value, and the tube voltage and the tube current are held in the upper limit values of the respective allowable ranges. It is possible to obtain an X-ray fluoroscopic image having a desired luminance.

On the other hand, if the real tube voltage Vr that is changed every time falls below the lower limit value VdL of the allowable range, that is, if the luminance of the X-ray fluoroscopic image exceeds, the CPU 1a determines the allowable lower limit value VdL and the real tube value. Based on the tube current Ad acting to make the difference between the voltages Vr zero, based on the current tube current Ad, the above equation (2-2), ie, Ad = β (Vr-VdL) + Ad (2-2) If the determined tube current Ad does not fall below the lower limit value AdL of the permissible range (S13), the tube current Ad is set in the tube current creation unit 1c (S14), and these operations are performed. The repetition is performed in a range where Ad does not exceed the lower limit value AdL of the allowable range (S12, S13, S14).

As a result, the tube current is reduced by an amount proportional to the difference between the allowable lower limit value VdL and the actual tube voltage Vr according to the equation (2-2), whereby the luminance detected by the camera control unit 10 is obtained. Decreases, and the tube current set when the actual tube voltage Vr finally reaches the lower limit value VdL stabilizes.

Therefore, the actual tube current Ad is lower than the allowable lower limit value AdL.
If the actual tube voltage Vr does not fall below the lower limit value V of the allowable range,
By adjusting the tube current separately from the relationship between the tube voltage and the tube current shown in FIG. 2 in the state of holding at dL, it becomes possible to obtain an X-ray fluoroscopic image having a desired luminance.

Next, as a result of obtaining a tube current Ad acting to make the difference between the allowable lower limit value VdL and the actual tube voltage Vr zero, if the tube current Ad to be set does not fall within the allowable range, that is, If the actual tube voltage Vr does not increase to the allowable lower limit value VdL even when the tube current is reduced to the lower limit value AdL of the allowable range, the CPU 1a stores the allowable lower limit value A in the memory 1b.
dL is set (S13, S15). Then, based on the current opening OPd of the iris 8, the actual tube voltage becomes Vr.
The opening OPd of the new iris 8 is determined based on the above equation (3-2) so that the difference between the iris 8 and the allowable lower limit value VdL becomes zero, and the iris 8 is controlled via the iris control unit 1e so that the opening OPd becomes the opening ( S16). OPd = γ (Vr−VdL) + OPd (3-2)

These operations are repeated until the actual tube voltage Vr becomes equal to or higher than the allowable lower limit value VdL (S17,
S16). As a result, the brightness of the X-ray fluoroscopic image can be further reduced, so that the brightness detected by the camera control unit 10 further approaches the reference value, and the tube voltage and the tube current are held at the lower limit values of the respective allowable ranges. In this state, an X-ray fluoroscopic image having a desired luminance can be obtained.

[0032]

According to the present invention, in order to obtain a desired luminance for an X-ray fluoroscopic image, even if the tube voltage is out of the allowable range, the tube voltage is set to the upper limit or the lower limit of the allowable range. Is determined, and the X-ray tube is controlled so that the tube voltage becomes the same as the tube voltage. Therefore, the desired luminance is obtained while the tube voltage is maintained at the upper limit or the lower limit of the allowable range. It is possible to adjust the tube current value of the X-ray tube so as to obtain an X-ray image. Therefore, an X-ray fluoroscopic image having a desired luminance can be obtained in a state where the tube voltage is kept within an allowable range.

When the tube current value is outside the allowable range in addition to the tube voltage adjusted to obtain the desired luminance for the X-ray fluoroscopic image, the difference between the tube voltage and the allowable upper limit or lower limit becomes zero. Since the aperture of the iris is controlled so that the X-ray of the desired brightness is obtained by adjusting the aperture of the iris in a state where both the tube current and the tube voltage are out of the permissible range and are held near the respective upper and lower limits. Images can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of an X-ray imaging apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a tube voltage to be set and a tube current.

FIG. 3 is a diagram showing a relationship between insufficient tube voltages corresponding to insufficient luminance.

FIG. 4 is a flowchart showing the operation of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... X-ray control apparatus 1a ... CPU 1b ... Memory 1c ... Tube current creation part 1d ... Tube voltage creation part 1e ... Iris control part 2 ... Operation panel 3 ... X-ray tube 4 ... Subject 5 ... Table 6 ... Image intensity Fire bearing 7 ... Optical system 8 ... Iris 9 ... Camera 10 ... Camera control unit 11 ... Monitor

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05G 1/32 H05G 1/32 Z 1/34 1/34 Z 1/64 1/64 E

Claims (3)

[Claims] An X-ray control apparatus for controlling an X-ray tube so as to obtain an X-ray fluoroscopic image having a desired luminance, comprising: determining a tube voltage for obtaining a desired luminance based on luminance information of the X-ray fluoroscopic image; A tube voltage control means for controlling the X-ray tube so as to be a tube voltage; and determining a tube current corresponding to the determined tube voltage from a preset tube voltage-tube current relationship, which becomes the same tube current. When the determined tube voltage is out of the allowable range, the tube current is determined so that the difference from the allowable upper limit value or lower limit value becomes zero, and the tube current becomes the same. An X-ray control device comprising: a tube current control means for controlling an X-ray tube. 2. The X-ray controller according to claim 1, wherein
Further, an iris control means is provided for changing and controlling the iris opening of the X-ray detector so that the difference between the determined tube current and the allowable upper limit value or lower limit value of the tube voltage becomes zero when the determined tube current is out of the allowable range. An X-ray control device, characterized in that: 3. An X-ray tube, an X-ray detector comprising an image intensifier, an iris, and a camera, and the X-ray controller according to claim 1 or 2. X-ray imaging device.