JP2011239803A - X-ray fluoroscopic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray fluoroscopic apparatus capable of quickly obtaining appropriate images even when a collimator is in a closed state and reducing the amount of X-ray exposure to a subject.SOLUTION: The X-ray fluoroscopic apparatus includes an automatic luminance control circuit 12 for making constant the luminance of images displayed on an image display part 31, and a collimator control part 25 detecting the open amount of collimator leaves in a collimator part 23. A control part 10 stops feedback control of X-ray output by the automatic luminance control circuit 12 when the open amount of the collimator leaves is a predetermined value or less.

Description

  The present invention relates to an X-ray fluoroscopic apparatus, and more particularly to an X-ray fluoroscopic apparatus that performs fluoroscopy or continuous imaging.

  In an X-ray fluoroscopic apparatus that performs fluoroscopy, an automatic luminance control method called IBS or ABC is employed in order to keep the luminance of an image displayed on an image display unit constant. An X-ray fluoroscopic apparatus that performs continuous imaging also employs an exposure control system called AEC that obtains predetermined image brightness by automatically blocking X-rays according to the incident dose. These control methods feedback control the tube voltage and tube current applied to the X-ray tube based on the image signal from the X-ray detector in order to keep the brightness of the image displayed on the image display unit constant. (See Patent Document 1).

  In addition, between the X-ray tube and the X-ray detector, the X-ray irradiation area of the X-ray tube from the X-ray tube can be opened and closed to regulate the irradiation area of the X-ray irradiated to the subject. A collimator unit having a plurality of collimator leaves disposed in the is installed. The opening amount of the collimator leaf in the collimator unit is adjusted by an operator in order to reduce the X-ray exposure amount according to the target site to be observed (see Patent Document 2).

Japanese Patent Laid-Open No. 9-234198 JP 2007-213979 A

  For example, when performing aging, X-ray tube test output, or the like, the collimator leaf in the collimator unit may be disposed at the closed position in order to prevent X-rays from leaking to the outside. For this reason, when performing fluoroscopy or radiography using the X-ray fluoroscopic imaging apparatus after these operations, the collimator leaf may be unintentionally disposed at the closed position. In such a case, when fluoroscopy or continuous imaging is started in a state where feedback control for making the brightness constant is performed, it is determined that the brightness is extremely low because X-rays do not reach the X-ray detector, The X-ray output condition is adjusted to the maximum output.

  When the operator notices this and operates the collimator unit to open the collimator leaf to a predetermined position, the X-ray output condition gradually decreases from the maximum output, and the automatic brightness control mechanism provides an appropriate output after a certain time. . However, not only does the subject receive unnecessary exposure during this period, but there is a problem that a useless time elapses while an image unnecessary for diagnosis is taken.

  The present invention has been made to solve the above-mentioned problems, and even when the collimator is in a closed state, an appropriate image can be quickly obtained, and the X-ray exposure dose to the subject can be reduced. An object of the present invention is to provide an X-ray fluoroscopic apparatus that can be used.

  The invention according to claim 1 is an X-ray tube that irradiates X-rays, an X-ray detector that detects X-rays that have passed through the subject, and an image based on an image signal from the X-ray detector. In an X-ray fluoroscopic apparatus having an image display unit for display, in order to make the luminance of an image displayed on the image display unit constant, the X-ray tube is controlled based on an image signal from the X-ray detector. An automatic luminance control means for feedback control of the tube voltage and tube current to be applied, and a plurality of collimator leaves disposed in an X-ray irradiation area from the X-ray tube so as to be openable and closable, are irradiated from the X-ray tube. A collimator unit that regulates the irradiation area of the subject with X-rays, an open / closed degree detecting unit that detects an open amount of the collimator leaf in the collimator unit, and an open amount of the collimator leaf detected by the open / closed degree detector Less than Sometimes, characterized in that a control unit for stopping the feedback control of the tube current and tube voltage by the automatic brightness control means.

  According to a second aspect of the present invention, in the first aspect of the present invention, when the opening amount of the collimator leaf detected by the opening / closing degree detecting means is below a certain level, a warning is displayed.

  According to the first aspect of the present invention, since the control of the tube current and the tube voltage by the automatic brightness control means is stopped when the opening amount of the collimator leaf is below a certain level, the collimator leaf of the collimator section is closed unintentionally. Even if it is located at or near the position, the output of the X-ray tube can be set to an appropriate value in a short time, and a proper image can be obtained quickly, and unnecessary X-rays to the subject can be obtained. The exposure dose can be reduced.

  According to the invention described in claim 2, since the warning is displayed when the opening amount of the collimator leaf is below a certain value, the operator can quickly recognize the state of the collimator leaf and change the opening amount. . For this reason, it is possible to quickly obtain an appropriate image by setting the output of the X-ray tube to an appropriate value in a shorter time, and it is possible to further reduce the amount of unnecessary X-ray exposure to the subject. .

1 is a schematic diagram of an X-ray fluoroscopic apparatus according to the present invention. 4 is a perspective view showing a main part of a collimator unit 23. FIG. 1 is a block diagram showing a main electrical configuration of an X-ray fluoroscopic apparatus according to the present invention. 3 is a graph showing a relationship between an opening amount of a collimator leaf 24 and an output of X-rays irradiated from an X-ray tube 21. 3 is a graph showing a relationship between an opening amount of a collimator leaf 24 and an output of X-rays irradiated from an X-ray tube 21.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view of an X-ray fluoroscopic apparatus according to the present invention, and FIG. 2 is a perspective view showing a main part of the collimator unit 23.

  This X-ray fluoroscopic imaging apparatus performs fluoroscopy, and includes a table 27 on which a subject 26 is placed, an X-ray tube 21, and an X-ray irradiated from the X-ray tube 21 and passing through the subject 26. A flat panel detector 22 serving as an X-ray detector for detecting the X-ray, and a collimator unit 23 for changing the size of the visual field, which is an area where the X-ray emitted from the X-ray tube 21 is irradiated to the subject 26. Prepare. As shown in FIG. 2, the collimator unit 23 includes four collimator leaves 24 that can reciprocate. By the action of the collimator unit 23, a visual field E that is an X-ray region irradiated from the X-ray tube 21 to the subject is defined.

  FIG. 3 is a block diagram showing the main electrical configuration of the X-ray fluoroscopic apparatus according to the present invention.

  The X-ray fluoroscopic apparatus includes a control unit 10 that controls the entire apparatus. The control unit 10 is connected to the flat panel detector 22 described above. The control unit 10 is connected to the collimator unit 23 described above via a collimator control unit 25 that controls the opening / closing operation of the collimator leaf 24 in the collimator unit 23. The collimator control unit 25 functions as an open / closed degree detection unit that detects the opening amount of the collimator leaf 24 in the collimator unit 23.

  The control unit 10 is connected to the X-ray tube 21 described above and an X-ray tube control unit 28 that applies a tube voltage and a tube current to the X-ray tube 21 to control the X-ray output. ing. In this X-ray fluoroscopic apparatus, the opening amount of the collimator leaf 24 in the collimator unit 23 and the output of X-rays irradiated from the X-ray tube 21 are controlled by the control unit 10. Further, the control unit 10 is also connected to an image display unit 31 for displaying an X-ray fluoroscopic image and other images, and an input unit 32 such as a keyboard.

  The control unit 10 includes an image processing unit 11 and an automatic luminance control circuit 12. Here, the image processing unit 11 performs image processing on the image signal from the flat panel detector 22 and displays an appropriate perspective image on the image display unit 31. Further, the automatic luminance control circuit 12 applies the voltage from the X-ray tube control unit 28 to the X-ray tube 21 based on the image signal from the flat panel detector 22 in order to keep the luminance of the image displayed on the image display unit 31 constant. This is for feedback control of the tube voltage and the tube current. As the automatic luminance control circuit 12, for example, an IBS circuit or an ABC circuit is used.

  The control unit 10 is configured to stop feedback control of the output of the X-ray tube 21 by the automatic luminance control circuit 12 when the opening amount of the collimator leaf 24 is below a certain level. Further, the control unit 10 is configured to display a warning on the image display unit 31 when the opening amount of the collimator leaf 24 is less than a certain value after the start of fluoroscopy.

  When performing fluoroscopy with respect to the subject 26 with such an X-ray fluoroscopic apparatus, the operator manually operates the open / close button of the collimator leaf 24 before or after the start of fluoroscopy. A field of view E that is an X-ray region irradiated from 21 to the subject is set.

  However, when the collimator leaf 24 is closed, such as when aging or X-ray tube test output is performed, the operator may forget to open the collimator leaf 24 before performing fluoroscopy. In this case, the X-rays irradiated from the X-ray tube 21 do not reach the flat panel detector 22. Therefore, when the X-ray irradiation is started, the automatic brightness control circuit 12 determines that the brightness of the image displayed on the image display unit 31 is low, and outputs the X-ray tube 21 to the X-ray tube control unit 28. Since the command is issued so as to increase, the output of the X-ray irradiated from the X-ray tube 21 is adjusted to the maximum output.

  When the operator notices this and opens the collimator leaf 24 in the collimator unit 23, the output of the X-rays emitted from the X-ray tube 21 gradually decreases, but it takes a long time to reach an appropriate output. For this reason, in the X-ray fluoroscopic apparatus according to the present invention, the feedback control of the output of the X-ray tube 21 by the automatic luminance control circuit 12 is stopped when the opening amount of the collimator leaf 24 is below a certain level.

  4 and 5 are graphs showing the relationship between the amount of opening of the collimator leaf 24 and the output of X-rays emitted from the X-ray tube 21. FIG. This graph shows a case where the collimator leaf 24 in the collimator unit 23 is closed. 4 shows a state in which feedback control of the output of the X-ray tube 21 by the automatic luminance control circuit 12 is always executed, and FIG. 5 shows the automatic luminance control circuit 12 when the opening amount of the collimator leaf 24 is below a certain level. This shows a state where feedback control of the output of the X-ray tube 21 is stopped.

  In the state where the feedback control of the output of the X-ray tube 21 by the automatic luminance control circuit 12 shown in FIG. 4 is always executed, the output of the X-rays emitted from the X-ray tube 21 becomes a preset initial condition. Yes. This initial condition is an output value based on a tube voltage and a tube current value set in advance according to an imaging region and imaging conditions.

  When X-rays are irradiated from the X-ray tube 21 under these initial conditions, the collimator leaf 24 in the collimator unit 23 is closed, so that the luminance of the image displayed on the image display unit 31 by the automatic luminance control circuit 12 is high. The output of the X-ray irradiated from the X-ray tube 21 is increased from the initial condition until it reaches the maximum output by the action of the feedback control by the automatic luminance control circuit 12 as determined to be low.

  At this time, a warning is displayed on the image display unit 31 according to a command from the control unit 10. For this reason, the operator notices that the collimator leaf 24 is closed at the time indicated by the symbol T in FIG. 4, and transmits an opening command of the collimator leaf 24 from the input unit 32 to the collimator control unit 25. As a result, when each collimator leaf 24 moves in the opening direction, the output of X-rays emitted from the X-ray tube 21 decreases to a set value after a slight time lag.

  In this case, the output of the X-rays emitted from the X-ray tube 21 does not become the set value even after the opening amount of the collimator leaf 24 in the collimator unit 23 becomes 100% with respect to the set opening amount. In other words, the output of X-rays irradiated from the X-ray tube 21 continues to be in a lowered state. For this reason, the time shown with the code | symbol t in FIG. 4 passes. During this time t, the subject 26 is not only exposed to unnecessary exposure, but also a problem that unnecessary time elapses while an image unnecessary for diagnosis is taken.

  On the other hand, in the state where feedback control of the output of the X-ray tube 21 by the automatic luminance control circuit 12 is stopped when the opening amount of the collimator leaf 24 is equal to or less than a certain level as shown in FIG. The output of the X-rays changes with the initial condition set in advance as long as the opening amount of the collimator leaf 24 in the collimator unit 23 is below a certain level.

  At this time, a warning is displayed on the image display unit 31 according to a command from the control unit 10. For this reason, the operator notices that the collimator leaf 24 is closed at the time indicated by the symbol T in FIG. 5, and transmits an opening command of the collimator leaf 24 from the input unit 32 to the collimator control unit 25. Thereby, when each collimator leaf 24 moves in the opening direction, feedback control of the output of the X-ray tube 21 by the automatic luminance control circuit 12 is started from the time T2 when the opening amount of the collimator leaf becomes equal to or larger than a certain value.

  For this reason, as shown in FIG. 5, immediately after the opening amount of the collimator leaf 24 in the collimator unit 23 becomes 100% of the set opening amount, the output of the X-rays irradiated from the X-ray tube 21 is the set value. It becomes. Therefore, not only can the subject 26 be prevented from receiving unnecessary exposure, but also the diagnosis can be executed quickly.

  In the above-described embodiment, the X-ray fluoroscopic apparatus that performs fluoroscopy has been described. However, the present invention may be applied to an X-ray fluoroscopic apparatus that performs continuous imaging. In this case, as the automatic brightness control circuit 12, for example, an automatic exposure control circuit called AEC is used.

DESCRIPTION OF SYMBOLS 10 Control part 11 Image processing part 12 Automatic brightness | luminance control circuit 21 X-ray tube 22 Flat panel detector 23 Collimator part 24 Collimator leaf 25 Collimator control part 26 Subject 27 Table 28 X-ray tube control part 31 Image display part 32 Input part

Claims (2)

An X-ray tube that emits X-rays, an X-ray detector that detects X-rays that have passed through a subject, and an image display unit that displays an image based on an image signal from the X-ray detector. In the X-ray fluoroscopic apparatus,
Automatic luminance control means for feedback-controlling the tube voltage and tube current applied to the X-ray tube based on the image signal from the X-ray detector in order to keep the luminance of the image displayed on the image display unit constant; ,
A collimator section that includes a plurality of collimator leaves disposed in an X-ray irradiation area from the X-ray tube so as to be openable and closable;
An open / closed degree detecting means for detecting an opening amount of a collimator leaf in the collimator unit;
A control unit for stopping the feedback control of the tube current and the tube voltage by the automatic luminance control unit when the opening amount of the collimator leaf detected by the open / closed degree detection unit is below a certain level;
An X-ray fluoroscopic apparatus comprising: The X-ray fluoroscopic apparatus according to claim 1,
An X-ray fluoroscopic apparatus that displays a warning when the opening amount of the collimator leaf detected by the opening / closing degree detecting means is below a certain level.

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