JP2000261724A - X-ray device and photographing condition setting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a photographing condition and to set it without test exposure to a test object and independently of a method for radioscopic control. SOLUTION: A photographing condition calculation section 10 of an X-ray controller 8 calculates a photographing condition on the basis of a prescribed arithmetic expression from radioscopic conditions (tube voltage, tube current and pulse width or the like) in the case of radioscopy. Since the photographing conditions are calculated by the arithmetic operation, test exposure before the photographing is not required and the exposure to the test object can be reduced. Even when the device is a device conducting consecutive radioscopy or a pulse radioscopy in the case of radioscopy, the photographing conditions can be obtained for the both. In other words, the photographing conditions can be obtained independently of the radioscopic method adopted by the device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray apparatus suitable for use in an apparatus for imaging a subject using X-rays, such as an X-ray diagnostic apparatus or an X-ray CT apparatus. An X-ray apparatus that calculates the imaging conditions from the conditions, thereby eliminating the need for test exposure for obtaining the imaging conditions and setting the imaging conditions without depending on the fluoroscopic method employed by the apparatus. And a shooting condition setting method.

[0002]

2. Description of the Related Art Conventionally, in an X-ray diagnostic apparatus, imaging conditions mainly including a tube voltage, a tube current and a pulse width are set in advance so that an X-ray image optimal for diagnosis of a subject can be obtained. I do. As the setting method of the imaging conditions, a test exposure is performed before the imaging, and the imaging conditions are set based on the test exposure result, and the imaging is performed using the tube voltage of the fluoroscopy conditions used in the fluoroscopy before the imaging. Method of setting conditions (F-
ATR) is known.

When the imaging conditions are set by the test exposure, several X-rays are radiated to the subject on a trial basis while gradually increasing the X-ray dose before the actual imaging of the subject. Then, an optimum photographing condition is obtained based on the test exposure result.

The setting of imaging conditions using a tube voltage at the time of fluoroscopy is performed by an X-ray diagnostic apparatus having a continuous fluoroscopy function of continuously irradiating weak X-rays during fluoroscopy to perform fluoroscopy. That is, X having such a continuous fluoroscopic function
In the X-ray diagnostic apparatus, since the change in the tube voltage during fluoroscopy corresponds to the change in the subject thickness one-to-one, the imaging state during imaging can be estimated from the tube voltage during fluoroscopy. Therefore, by setting the imaging conditions so as to correspond to the tube voltage at the time of fluoroscopy, it becomes possible to obtain an optimal X-ray image at the time of imaging. In this case, since the pulse width of the imaging conditions is finally controlled by the ABC function at the time of X-ray irradiation, the maximum value is set.

[0005]

However, in the method of setting imaging conditions by test exposure, it is necessary to perform test exposure when setting imaging conditions, so that X-rays that are not necessary for diagnosis are applied to the subject. Therefore, there is a problem from the viewpoint of reducing the exposure of the subject.

A method of setting imaging conditions using a tube voltage at the time of fluoroscopy is only possible in an X-ray diagnostic apparatus having a continuous fluoroscopy function. For this reason, there is a problem that it cannot be easily applied to all devices (depends on a fluoroscopy control method).

That is, in the case of performing continuous fluoroscopy, the tube voltage changes continuously with the increase of the subject, so that the change in the tube voltage and the change in the thickness of the subject are associated with each other on a one-to-one basis. For this reason, it is possible to determine the imaging conditions based on only the tube voltage for fluoroscopy.

Here, some recent X-ray diagnostic apparatuses include an X-ray diagnostic apparatus that controls a tube current and a pulse width while keeping a tube voltage constant during fluoroscopy, and a tube voltage, a tube current, and a pulse width. There is also an X-ray diagnostic apparatus that performs control for continuously changing all conditions. In these X-ray diagnostic apparatuses, a change in tube voltage and a change in subject thickness during fluoroscopy do not correspond to 1: 1 (because a tube voltage, a tube current, and a pulse width change in a complicated manner). The photographing conditions cannot be set based on the tube voltage. Further, even if only the pulse width and the tube current are set as conditions, the photographing conditions cannot be set for the same reason.

[0009] The present invention has been made in view of the above-described problems, and does not require test exposure to a subject.
It is another object of the present invention to provide an X-ray apparatus and an imaging condition setting method capable of setting imaging conditions without depending on a fluoroscopic control method.

[0010]

An X-ray apparatus according to the present invention includes, as means for solving the above-mentioned problems, an X-ray generating means for irradiating an object with X-rays; X formed by exposing the subject to X-rays
X-ray detection means for detecting a line image, and the X-ray generation means for controlling the X-ray generation means so as to irradiate a subject with X-rays having a small dose during fluoroscopy, and X-rays having a larger dose during radiography at the time of imaging. Exposure control means for controlling the X-ray generation means so as to irradiate the subject with X-rays, and fluoroscopic X-ray energy detection means for detecting X-ray energy of X-rays irradiated to the subject during the fluoroscopy. Having.

Further, together with each of these means, an imaging X-ray energy calculating means for calculating an X-ray energy required at the time of imaging based on the X-ray energy at the time of fluoroscopy detected by the fluoroscopic X-ray energy detecting means, Imaging condition setting means for setting imaging conditions corresponding to X-ray energy required at the time of imaging calculated by the imaging X-ray energy calculation means, and imaging for controlling imaging of a subject under the imaging conditions set by the imaging condition setting means Control means.

Further, the method for setting photographing conditions according to the present invention comprises:
As means for solving the above-mentioned problems, a step of detecting the X-ray energy of the X-ray radiated to the subject at the time of fluoroscopy,
The method includes a step of calculating X-ray energy required at the time of imaging based on the line energy, and a step of detecting and setting imaging conditions based on the X-ray energy required at the time of imaging calculated at the step.

The X-ray apparatus and the imaging condition setting method according to the present invention are based on the X-ray energy during fluoroscopy.
X-ray energy required at the time of imaging is calculated, and imaging conditions are set so that the calculated X-ray energy required at the time of imaging is obtained.

Thus, since the imaging conditions at the time of imaging can be obtained based on the X-ray energy at the time of fluoroscopy, test exposure to be performed on the subject before imaging can be eliminated. In addition, regardless of whether the fluoroscopic method is a continuous fluoroscopic method or a pulse fluoroscopic method, the imaging condition at the time of imaging can be obtained based on the X-ray energy at the time of the fluoroscopy, and thus depends on the control method of fluoroscopy. The photographing conditions can be set without any need.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an X-ray apparatus and an imaging condition setting method according to the present invention will be described below in detail with reference to the drawings.

[Overall Configuration of the Embodiment] The X-ray apparatus and the imaging condition setting method according to the present invention can be applied to an X-ray diagnostic apparatus as shown in FIG. The X-ray diagnostic apparatus according to the embodiment of the present invention includes an X-ray tube and an I.V. tube which are arranged at both ends of a C-shaped arm so as to face each other. I. -TV system.

More specifically, an X-ray tube 2 for irradiating an X-ray to a subject placed on a bed 1 and an X-ray for adjusting the quality of the X-ray emitted from the X-ray tube 2 are provided. An X-ray filter 3 and an image for converting an X-ray image formed by exposing X-rays from the X-ray tube 2 to the subject through the X-ray filter 3 into an optical image.
Intensifier 4 (II) and I.I. I. 4 and a photomultiplier 5 provided at the subsequent stage; I. 4
A television camera 6 (TV camera) that takes in the X-ray image converted into an optical image by the 供給 す る and supplies it as an electric image signal to a television monitor 7 (TV monitor), and an X-ray that controls the entire X-ray apparatus. It has a control device 8.

An X-ray control unit 8 is an ABC control unit 9 (ABC: automatic brightness adjustment) for setting a see-through condition in "see-through" in which a subject is exposed to a small dose of X-rays to obtain a coarse X-ray image. ), And a photographing condition calculating unit 10 that calculates and sets photographing conditions at the time of photographing based on the fluoroscopic conditions set by the ABC control unit 9 during fluoroscopy.

[Overall Operation of the Embodiment] In such an X-ray diagnostic apparatus, X-ray irradiation for fluoroscopy is performed from the X-ray tube 2 under the conditions specified by the X-ray control device 8. The X-rays emitted from the X-ray tube 2 are adjusted in quality through an X-ray filter 4 and are emitted to a subject. Thus, an X-ray image is formed. This X-ray image was obtained from I. 4 and TV camera 6
Is converted into a viewable image and supplied to the TV monitor 7. As a result, a small dose of X is emitted during fluoroscopy.
A coarse X-ray image formed by the lines is displayed on the TV monitor 7.

The ABC control section 9 of the X-ray control device 8 has the I.D.
I. 4 based on a signal from the photomultiplier 5 provided at the subsequent stage or an image signal from the TV camera 6.
In order to keep the brightness of the display image on the TV monitor 7 constant,
Field-back control is performed to change the fluoroscopic conditions and drive the X-ray tube 2 again. Thus, the brightness of the display image on the TV monitor 7 is controlled to be always constant according to the thickness of the subject (subject thickness).

[Operation for Setting Imaging Conditions] Here, the X-ray control device 8 is provided with an imaging condition calculation unit 10. When the above-mentioned “perspective” ends, the imaging condition calculation unit 10 ends. , The fluoroscopic conditions (tube voltage, tube current, pulse width, etc.) set by the ABC control unit 9 at that time; I. 4
And the output of the photomultiplier 5 used for the automatic brightness adjustment of the ABC control unit 9.
Alternatively, an image signal or the like from the TV camera 6 is recorded. Then, based on these pieces of information, “transparent X-ray energy”, “dose ratio”, and “imaging X-ray energy” are calculated, and imaging conditions at the time of imaging are set based on the respective calculation results.

(Operation for Calculating Fluorescence X-ray Energy) That is, when the “radiography” ends, the imaging condition calculation unit 10 first calculates the X-ray energy during fluoroscopy. Specifically, the X-ray energy at the time of fluoroscopy is calculated based on the following equation (a) in order to link the fluoroscopy condition and the subject thickness 1: 1.

X-ray fluoroscopy energy = energy function per 1 mA (φ: kV) × tube current during fluoroscopy (mA) × pulse width during fluoroscopy (msec) × I. I. 4 (kV) × ABC correction parameter (a) By using the equation (a), the fluoroscopic control method applied to the X-ray apparatus can be changed to “continuous fluoroscopic” or a predetermined interval. In any case of “pulse fluoroscopy” in which fluoroscopy is performed intermittently with the pulse of, the fluoroscopic X-ray energy during fluoroscopy can be calculated. In the case of “continuous fluoroscopy”, a fixed value corresponding to the control of the apparatus may be given as the pulse width. The ABC correction parameter uses the data of the photomultiplier 3 used for ABC control or the image level information of the TV camera 1 when the fluoroscopy condition reaches the upper limit due to the system limitation as described above. This is a parameter set as

Here, the energy function φ (kV) per 1 mAs and the tube voltage (kV) have a non-linear relationship as shown in FIG. This curve differs depending on the type and thickness of the X-ray filter 4 for adjusting the radiation quality to be used. Further, in a device capable of controlling the radiation quality by the X-ray filter 3,
By preparing this function φ for the quality of the X-ray filter 3, it is possible to cope with it. Energy function per 1 mA φ
(KV) can be used as a function of the tube voltage or as a table.

For example, assuming that the energy function φ is a quartic function of the tube voltage, the energy function φ is calculated by the following equation (b).

Φ (kV) = A × (tube voltage) ⁴ + B × (tube voltage) ³ + C × (tube voltage) ² + d × tube voltage + e (b) In this equation (b), A, B, C, d, and e indicate coefficients of a quartic function, respectively.

(Calculation Operation of Dose Ratio) Next, the imaging condition calculation unit 10 determines the I.D. in the ABC control during fluoroscopy.
I. Based on the incident dose to No. 4, the dose ratio between the fluoroscopic X-ray energy and the X-ray energy required for imaging is calculated using the following equation (c). For example, the I.D. I. 4 was changed to FX (R / m
in), when the incident dose at the time of imaging is RX (R / min), the dose ratio is as follows: dose ratio = RX / FX (c).

(Estimation Operation of Incident Dose Correction Parameter) Next, the imaging condition calculation unit 10 I. The incident dose correction parameter of No. 4 is estimated. That is, when the ABC control is performed, the brightness of the TV monitor 7 can be kept constant. I. The incident dose to 4 is not constant over all available tube voltages. For this reason, the photographing condition calculation unit 10 sets the I. I. 4 is calculated, and according to this parameter, I.V. I. 4 is corrected. As the incident dose correction parameter, the incident dose correction parameter corresponding to the tube voltage may be detected in advance and tabulated, and the incident dose correction parameter may be read from this table and used at the time of actual estimation, or the incident dose correction parameter may be used. A formula for calculating the correction parameter may be formed into a mathematical formula, and the incident dose correction parameter may be calculated based on the formula at the time of actual estimation. In any case, more accurate parameter estimation becomes possible.

(Calculation operation of imaging X-ray energy)
The imaging condition calculation unit 10 calculates the imaging X-ray energy based on the following equation (d) using the “transmitted X-ray energy”, “dose ratio”, and “incident dose correction parameter” calculated or estimated as described above.

Imaging X-ray energy = transmission X-ray energy × dose ratio × incident dose correction parameter (d) (Calculation operation of imaging conditions) The photographing condition is calculated based on “energy”.

Assuming that the imaging conditions consist of a tube voltage, a tube current and a pulse width, the imaging X-ray energy can be calculated as shown in the following equation (e): imaging X-ray energy = φ × tube current × pulse width × incident Dose correction parameter (e) (φ is an energy function per 1 mAs).

The photographing condition calculation unit 10 determines the photographing conditions based on the equation (e). At this time, the “tube current” is set as the maximum condition that can be used.
“Pulse width” is set to a predetermined fixed value.

The "tube voltage" is set to a target tube voltage range of, for example, 60 kV to 80 kV. If the tube voltage is lower than the minimum tube voltage of 60 kV, the tube current is gradually reduced from the maximum value. When the tube current becomes the lowest value (60 kV in this example), the target tube voltage range is reduced to, for example, 50 kV to 60 kV, and the tube voltage is determined from the range. These conditions may be registered in advance as photographing condition control data, and optimal data may be selected from the registered photographing condition control data when calculating actual photographing conditions. Alternatively, the user may input desired conditions.

The X-ray controller 8 controls the X-ray tube 2 based on the imaging conditions thus detected from the imaging condition table.
The actual photographing is performed by controlling the driving of the camera.

(Shooting Condition Table) Next, the above is an example of calculating shooting conditions by calculation.
May be provided, and the corresponding photographing condition may be read from the photographing condition table and set. That is, the imaging condition table shown in FIG. 3 includes, for example, “energy function φ per 1 mA”, “tube current”, “perspective pulse width”,
“I.I.4 incident dose correction parameter”, “X
“Line energy” is stored as the imaging condition.

In the case where such a photographing condition table is provided, for example, "tube voltage"
The “tube current” and the “pulse width” are “95 (k
V), "50 (mA)", and "4 (msec)", and the X-ray energy under these fluoroscopic conditions is "13148".
38600 "and the dose ratio is calculated as" 6 ",
I. I. Assuming that the tube voltage correction parameter of No. 4 is “1.0”, the required imaging X-ray energy is the imaging X-ray energy estimated from the fluoroscopy by the above formula (d) = 7899031.
600.

When the calculated X-ray energy is compared with the imaging condition table shown in FIG.
As shown by hatching in FIG.
“76 (kV)”, “630 (mA)”, “4 (mse)
c) ”,“ tube voltage ”,“ tube current ”, and“ pulse width ”can be obtained as imaging conditions. The X-ray controller 8 drives and controls the X-ray tube 2 and the like based on the imaging conditions detected from the imaging condition table in this manner, and performs actual imaging.

[Effects of the Embodiment] As is clear from the above description, the X-ray diagnostic apparatus of the embodiment calculates the imaging conditions from the fluoroscopic conditions at the time of fluoroscopy based on a predetermined arithmetic expression. Therefore, whether the X-ray diagnostic apparatus performs continuous fluoroscopy during fluoroscopy or the apparatus performs pulse fluoroscopy during fluoroscopy, the imaging conditions can be determined for each. In other words, the imaging conditions can be obtained without depending on the fluoroscopic method adopted by the X-ray diagnostic apparatus.

Further, since the imaging conditions are calculated from the fluoroscopic conditions at the time of fluoroscopy on the basis of a predetermined arithmetic expression, test exposure performed before imaging can be eliminated, and exposure to the subject can be reduced. And the X
The safety of the X-ray diagnostic apparatus can be improved.

The above embodiment is an example of the present invention. Therefore, the present invention is not limited to this embodiment. For example, in the description of the above embodiment, X
I. line detection means I. -TV system is used, which converts incident X-rays into light, converts the light into electric charges, and forms an imaging signal corresponding to an X-ray image. An X-ray flat panel detector having two-dimensionally arranged X-ray detectors may be used. Also,
The present invention is applied to an X-ray diagnostic apparatus. However, the present invention may be applied to any other apparatus that captures an X-ray image using X-rays, such as an X-ray CT apparatus. Is also applicable. Of course, other than these, various changes can be made according to the design and the like within a range not departing from the technical idea according to the present invention.

[0041]

According to the X-ray apparatus and the imaging condition setting method of the present invention, the imaging conditions at the time of imaging can be obtained based on the X-ray energy at the time of fluoroscopy. Can be eliminated. Also,
Even if the fluoroscopy method is a continuous fluoroscopy method, even if it is a pulse fluoroscopy method, imaging conditions at the time of imaging can be obtained based on the X-ray energy at the time of the fluoroscopy, without depending on the fluoroscopy control method Shooting conditions can be set.

[Brief description of the drawings]

FIG. 1 is a block diagram of an X-ray diagnostic apparatus according to an embodiment to which an X-ray apparatus and an imaging condition setting method according to the present invention are applied.

FIG. 2 is a characteristic diagram showing a relationship between an energy function φ per 1 mA and a tube voltage kV.

FIG. 3 is a diagram for explaining imaging conditions obtained corresponding to the imaging X-ray energy calculated by the X-ray diagnostic apparatus of the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Bed, 2 ... X-ray tube, 3 ... X-ray filter, 4 ... Image intensifier (II), 5 ... Photomultiplier, 6 ... TV camera, 7 ... TV monitor, 8 ... X-ray control Device, 9 ... ABC control unit, 10 ... Shooting condition calculation unit

Claims (5)

[Claims] An X-ray generating means for irradiating a subject with X-rays, and an X-ray detecting means for detecting an X-ray image formed by irradiating the subject with X-rays from the X-ray generating means. X-ray detection means, and the X-ray generation means is controlled so as to irradiate the subject with X-rays having a small dose at the time of fluoroscopy. Exposure control means for controlling the X-ray generation means so as to radiate, fluoroscopic X-ray energy detection means for detecting X-ray energy of X-rays radiated to a subject during the fluoroscopy, and fluoroscopic X-ray energy X-ray energy calculation means for calculating the X-ray energy required at the time of imaging based on the X-ray energy at the time of fluoroscopy detected by the detection means, and X-ray energy required at the time of imaging calculated by the X-ray energy calculation means Ray energy And imaging condition setting means for setting the photographing conditions corresponding to the ghee, X-rays apparatus characterized by having an imaging control means for capturing control of the object under the set photographing conditions by the imaging condition setting unit. 2. An imaging condition setting unit, comprising: at least an X-ray generation voltage of the X-ray generation unit as the imaging condition;
2. The X-ray apparatus according to claim 1, wherein an X-ray generation current and a pulse width of a driving pulse for driving the X-ray generation unit are set. 3. A fluoroscopic condition adjusting means for adjusting a fluoroscopic condition in fluoroscopy so that an X-ray image in fluoroscopy has a constant luminance, wherein said radiographic X-ray energy calculating means is said fluoroscopic condition adjusting means. X required at the time of shooting taking into account the fluoroscopic conditions adjusted in
3. The X-ray apparatus according to claim 1, wherein the X-ray energy is calculated. 4. The imaging condition setting means, wherein the X-ray energy required by the imaging calculated by the imaging X-ray energy calculation means is calculated.
An imaging condition table that stores and sets a plurality of imaging conditions corresponding to X-ray energies required at the time of imaging; The X-ray apparatus according to any one of claims 1 to 3, wherein an imaging condition corresponding to X-ray energy required at the time of imaging calculated by the means is read from the imaging condition table and set. . 5. A step of detecting X-ray energy of X-rays emitted to a subject at the time of fluoroscopy, and determining X-ray energy required at the time of imaging based on the X-ray energy at the time of fluoroscopy detected at the step. A method for setting an imaging condition, comprising: a step of calculating; and a step of detecting and setting an imaging condition based on the X-ray energy required at the time of imaging calculated in the step.