JP2009000253A - X-ray image photographing apparatus and x-ray image photographing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To confirm the positional relation of an X-ray tube and an X-ray sensor and to control an X-ray generation device according to the positional relation of both of them. <P>SOLUTION: In the step S101, the photographing of a stationary image is performed and X rays are subjected to exposure illumination to irradiate the X-ray sensor and converted to an electric signal to be captured as digital data. In the step S102, an irradiation field is recognized from the photographic result of the stationary image and the positional relation of the X-ray tube and the X-ray sensor is judged in the step S103 while it is judged whether the X-ray irradiation region T extracted in the step S102 comes within the X-ray sensor. If the whole region T is in the X-ray sensor, continuous photographing is permitted in the step S104 to be started in the step S105. If the region T comes outside of the X-ray sensor, an initial state is restored. The irradiation field is recognized in the step S106 and position judgment is succeedingly performed in the step S107. If the whole region T comes within the X-ray sensor, step processing is performed in the step S108 and, if the whole region T comes outside of the X-ray sensor, stop processing is performed in the step S109. X-ray fluoroscopic photographing is judged to be performed in the step S108 and, if the fluoroscopic photographing is succeeded, the irradiation field is recognized in the step S106 and, if the fluoroscopic photographing is completed, photographing is finished. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an X-ray imaging apparatus and an imaging method having a function of restricting X-ray imaging operations.

  Conventionally, a film screen system combining an intensifying screen and an X-ray photographic film is often used as an X-ray imaging apparatus in hospitals. According to this method, the X-rays that have passed through the subject are converted into visible light proportional to the X-ray intensity by the intensifying screen, the X-ray photographic film is exposed, and an X-ray image is formed on the film. Interpretation of this film is performed by using an observation device called Schaukasten. Further, as in Patent Document 1, an X-ray TV apparatus that performs fluoroscopic imaging in which an X-ray fluoroscopic image is displayed on a CRT using an image intensifier is also widely used in the medical field.

  In recent years, a high-resolution solid X-ray detector using an FPD (Flat Panel Detector) has been proposed. Thus, as in Patent Document 2, a subject is placed between an X-ray source and an X-ray sensor, and an X-ray image of the subject is obtained as digital data by converting the X-ray dose transmitted through the subject into an electrical signal. Is realized.

  Recently, as in Patent Document 3, a cassette type X-ray imaging apparatus capable of imaging with a sensor unit as a portable type has been put into practical use.

  On the other hand, as in Non-Patent Document 1, when X-ray fluoroscopy is performed using a cassette type sensor, the coincidence of the X-ray irradiation field with the image receiving surface is defined by the JIS standard or the like. Furthermore, a method for determining the imaging position by transmitting an electromagnetic wave from the X-ray generator side to the flat sensor as in Patent Document 4 has been proposed.

JP-A-5-064081 Japanese Patent No. 3066944 JP 2004-73354 A Japanese Patent No. 3624106 "JIS Handbook 2005 Radiation (Noh)", C0601-1-3 Medical Electrical Equipment Japan Standards Industry Association

  FIG. 9 is a schematic diagram showing the relationship between the X-ray flat panel detector and the X-ray irradiation area. When performing X-ray fluoroscopy using the cassette type flat detector 1, the flat detector 1 is disposed at a predetermined position, and an object is disposed on the flat detector 1 to perform X-ray imaging. At that time, the relationship between the X-ray emission region emitted from the X-ray tube and the flat detector 1 is such that the boundary between the X-ray irradiation region T along two orthogonal principal axes of the flat detector 1 and the flat detector 1 The deviation from the corresponding boundary should not exceed 3% of the distance between the focal point of the X-ray tube and the flat detector 1. Further, the sum of the deviations on both the main axes should not exceed 4% of the distance between the focal point of the X-ray tube and the flat detector 1.

The flat detector 1 and the X-ray irradiation area T are different from each other in the deviations x1 and x2 between the main axis Ay of the flat detector 1 and the X-ray irradiation area T, and the deviation y1 between the main axis Ax of the flat detector 1 and the X-ray irradiation area T. , Y2 must satisfy the following formula. Note that D represents the distance from the focal point of the X-ray tube to the flat detector 1.
| X1 | + | x2 | ≦ 0.03 · D
| Y1 | + | y2 | ≦ 0.03 · D
| X1 | + | x2 | + | y1 | + | y2 | ≦ 0.04 · D

  However, in the invention disclosed in Patent Document 4, although the sensor position can be detected, there is no means for controlling the X-ray imaging, and therefore the positional relationship between the X-ray source and the flat panel detector does not match at all. Even if it exists, there exists a problem that X-ray exposure can be performed.

  Similarly, the invention disclosed in Patent Document 3 also has no means for controlling X-ray imaging, and further, the positional relationship between the X-ray source and the flat detector is not taken into consideration, and the X-ray irradiates the flat detector at all. However, there is a problem that X-rays for fluoroscopy are irradiated even if the positional relationship is not.

  In addition, even if there is initially a positional relationship in which all the X-rays are applied to the flat detector, the X-rays do not hit the flat detector at all for some reason and the X-rays leak. However, there is a problem that X-rays for fluoroscopy are continuously emitted.

  An object of the present invention is to provide an X-ray imaging apparatus and imaging method imaging method that solves the above-described problems and recognizes the positional relationship of X-rays with respect to a flat detector and controls the X-ray imaging operation. .

  In order to achieve the above object, the technical feature of the X-ray imaging apparatus according to the present invention is that an X-ray source for irradiating X-rays and detecting the X-rays emitted from the X-ray source by a flat detector. An X-ray imaging apparatus for forming an X-ray image by performing an irradiation field recognition unit for recognizing an X-ray irradiation region, and the X-ray source based on the X-ray irradiation region recognized by the irradiation field recognition unit And a position determining means for determining a positional relationship between the flat detector and a control means for controlling an X-ray imaging operation based on a result determined by the position determining means.

  The technical feature of the X-ray image photographing method according to the present invention is that an X-ray image is formed by irradiating an X-ray from an X-ray source and detecting the irradiated X-ray with a flat detector. A step of recognizing an X-ray irradiation region irradiated with X-rays, a step of determining a positional relationship between the X-ray source and the flat detector based on the recognized X-ray irradiation region, and a result of the determination And a step of controlling the X-ray imaging operation based on the above.

  According to the X-ray imaging apparatus and imaging method according to the present invention, only when the positional relationship between the X-ray source and the flat detector ensures that all irradiation X-rays are at positions where the flat detector is irradiated. Shooting can be performed. In addition, when X-rays do not irradiate the flat detector at all during X-ray fluoroscopy and X-rays leak, the X-ray irradiation is automatically stopped to prevent unnecessary X-ray irradiation and exposure. It becomes possible.

  The present invention will be described in detail based on the embodiment shown in FIGS.

  FIG. 1 is a system configuration diagram of an X-ray imaging apparatus mounted on a roundabout car. A movable round-trip wheel 11 includes an X-ray generation unit 12 composed of an X-ray source, an X-ray sensor 13 that is a flat panel detector, a display unit 14, and a foot pedal 15, and is configured to perform general X-ray imaging. have.

  The X-ray generation unit 12 includes a mechanism for generating X-rays such as an X-ray tube and an X-ray diaphragm, and the X-ray sensor 13 receives the X-rays irradiated by the X-ray generation unit 12 and acquires an image signal. Detector. The display unit 14 is configured by a general monitor such as a CRT or a liquid crystal display, and displays image data, a GUI (graphical user interface), and the like on a screen. The foot pedal 15 is an input for instructing irradiation or stopping of X-rays. Device.

  Note that the X-ray imaging apparatus includes a general input device such as a keyboard and a mouse (not shown) in addition to the foot pedal 15, and includes a mechanism for inputting a user operation. In addition, a control device for controlling the X-ray imaging apparatus is incorporated in the casing of the round-wheel 11.

  FIG. 2 is a block circuit configuration diagram, and an X-ray generation unit 12, an X-ray sensor 13, an irradiation field recognition unit 22, and a position determination unit 23 are connected to the control unit 21 arranged in the housing of the round-wheel 11. Has been. The irradiation field recognizing unit 22 and the position determining unit 23 are arranged in the case of the round wheel 11 similarly to the control unit 21. ) Function by executing the program. The CPU can also be configured with an LSI, an ASIC, or the like.

  FIG. 3 is an operation flowchart of the X-ray imaging apparatus. First, in step S101, still image shooting is performed under the control of the control unit 21. In still image shooting, the X-rays emitted from the X-ray generation unit 12 pass through the subject and are irradiated to the X-ray sensor 13, converted into electric signals by the X-ray sensor 13, and captured as digital data. Still image shooting means one image, and it is sufficient to obtain an image that can recognize the irradiation field. Accordingly, the X-ray irradiation condition may be a normal still image shooting condition or a fluoroscopic condition.

  Next, in step S102, irradiation field recognition is performed from the still image shooting result. The irradiation field recognition process is performed by the irradiation field recognition unit 22 under the control of the control unit 21. Irradiation field recognition is a known technique for extracting an X-ray irradiation region T irradiated to the X-ray sensor 13 by performing image analysis processing. By performing this irradiation field recognition, irradiation onto the X-ray sensor 13 is performed. It is possible to know the X-ray region.

  In general, the X-ray irradiation region can be variously changed depending on the conditions of the X-ray generator. FIG. 4 is a schematic diagram of the X-ray generator 12 which is an X-ray generator. An opening is provided on the emission side of the normal X-ray generator 12, and the irradiation angle θ is determined in advance by this opening. Yes. An X-ray diaphragm 24 is provided in the opening, and the X-ray irradiation area T can be freely changed by opening / closing and adjusting the position of the X-ray diaphragm 24. Therefore, by adjusting the X-ray diaphragm 24, the target angle of X-ray irradiation and the shape of the X-ray irradiation region T can be variously changed. Depending on the shape of the X-ray diaphragm 24, the X-ray irradiation region T may have a hexagonal shape, an octagonal shape, or a circular shape.

  Next, position determination is performed at step S103. The position determination is performed by the position determination unit 23 under the control of the control unit 21, and it is determined whether the X-ray irradiation region T extracted in step S <b> 102 is within the X-ray sensor 13. Specifically, when the sides around the X-ray sensor 13 and the sides around the X-ray irradiation region T do not intersect, the X-ray irradiation region T irradiated to the X-ray sensor 13 is within the X-ray sensor 13. Is determined to be included.

  FIG. 5 shows an example in which the X-ray irradiation region T is included in the X-ray sensor 13, and the sides around the X-ray sensor 13 and the sides around the X-ray irradiation region T do not intersect. If the X-ray does not irradiate the X-ray sensor 13 at all, the irradiation field recognition unit 22 cannot recognize the X-ray irradiation region T, resulting in an error.

  On the other hand, as shown in FIG. 6, when any of the sides around the X-ray sensor 13 intersects with the sides around the X-ray irradiation region T, the X-ray irradiation region T irradiated to the X-ray sensor 13 is It is determined that it is not included in the X-ray sensor 13. Since the X-ray sensor 13 and the X-ray irradiation region T overlap, the side around the X-ray sensor 13 and the side around the X-ray irradiation region T intersect.

  As another method for determining the position, when there is no side where the side around the X-ray irradiation region T extracted in step S102 matches the side around the X-ray sensor 13, the X-ray irradiation region T is It is determined that it is within the X-ray sensor 13. When there is a side where the side around the X-ray irradiation region T and the side around the X-ray sensor 13 coincide, it is determined that the X-ray irradiation region T is not contained in the X-ray sensor 13.

  As described above, if the X-ray irradiation region T is entirely within the X-ray sensor 13 as a result of the position determination, the process proceeds to step S104. If the X-ray irradiation region T protrudes outside the X-ray sensor 13, the initial state is set. Return.

  Next, in step S104, the control unit 21 permits X-ray fluoroscopic imaging so that the user can select a fluoroscopy mode on the GUI, or when the control unit 21 has received a fluoroscopy request from the outside, the fluoroscopy is normally performed. There is a method to perform the operation.

  Here, X-ray fluoroscopic imaging means that there is a movement by continuously irradiating a subject with X-rays, converting the X-rays that have passed through the subject into electrical signals by the X-ray sensor 13 and continuously displaying them on a monitor. This is a shooting for confirming the image in real time. Here, it refers to all imaging techniques that are taken continuously, and includes cine imaging and contrast difference imaging called DSA in addition to fluoroscopic imaging. A lock may be applied so that the X-ray generation unit 12 and the X-ray sensor 13 do not move simultaneously with the X-ray fluoroscopic imaging permission.

  Next, X-ray fluoroscopic imaging is started in step S105. In the fluoroscopic imaging, the X-rays continuously exposed by the X-ray generator 12 are sequentially captured and displayed by the X-ray sensor 13 under the control of the controller 21.

  Next, irradiation field recognition is performed at step S106. Irradiation field recognition is performed by the irradiation field recognition unit 22 under the control of the control unit 21. The irradiation field recognition process itself is the same as the process performed in step S102, but the image to be processed is a still image in step S102, but in this step S106, one frame of a fluoroscopic image is used. Perform irradiation field recognition. Here, the image for the irradiation field recognition can be changed according to the shooting frame rate, and may be processed for all the frames, or may be processed at certain time intervals.

  Subsequently, position determination is performed in step S107. The position determination is determined by the position determination unit 23 under the control of the control unit 21, and this determination method is the same processing as step S103. If the X-ray irradiation area T is entirely within the X-ray sensor 13 as a result of the position determination, the process proceeds to step S108, and if the X-ray irradiation area T protrudes outside the X-ray sensor 13, the process of step S109 is performed.

  In step S108, determination is made during X-ray fluoroscopic imaging. Judgment during fluoroscopy can be considered as fluoroscopy when, for example, the exposure instruction unit such as the foot pedal 15 is in the exposure command state, or it can be said that fluoroscopy is being performed while the X-ray generation unit 12 is irradiating X-rays. . In any case, these pieces of information can be determined because the control unit 21 controls them. Here, if the fluoroscopic imaging is continuing, the process proceeds to step S106, and if the fluoroscopic imaging is completed, the imaging is ended.

  In step S109, fluoroscopic imaging is stopped. The fluoroscopic imaging is stopped when the control unit 21 instructs the X-ray generation unit 12 to stop the exposure. In addition, the fluoroscopic image reading operation of the X-ray sensor 13 is stopped.

  FIG. 7 is an operation flowchart of the second embodiment, and the same step numbers as those in FIG. 3 of the first embodiment indicate the same processing. The second embodiment is a case where the first embodiment is repeatedly performed, and X-ray fluoroscopic permission confirmation is performed in step S201. The confirmation of the fluoroscopic permission is a process performed by the control unit 21 and confirms whether or not the fluoroscopic imaging permission state is set. As a result of the confirmation, if the fluoroscopic imaging is permitted, the process proceeds to step S105. If the fluoroscopic imaging is not possible, the process proceeds to step S101.

  The processing after step S106 is the same as that of the first embodiment, but after the fluoroscopic imaging is stopped at step S109, the fluoroscopic imaging permission is canceled at step S202. The fluoroscopic imaging permission is canceled by the control unit 21. For example, even when a method for preventing the user from selecting the fluoroscopic imaging mode using the GUI or when the control unit 21 receives a fluoroscopic imaging request from the outside, There are methods to prevent shooting operations.

  In the position determination methods in the first and second embodiments, the determination was performed using the sides around the X-ray sensor 13 and the sides around the X-ray irradiation region T. In the third embodiment, instead of using the peripheral side of the X-ray sensor 13, a margin width is set by a threshold value inside the X-ray sensor 13, and the determination is performed using a side slightly inside the X-ray sensor 13. I do.

  FIG. 8 is an explanatory diagram of position determination according to the third embodiment. A square B provided at a fixed distance inside the X-ray sensor 13 is used for position determination instead of a side around the X-ray sensor 13. For example, the rectangle B is set approximately 1 cm from the periphery of the X-ray sensor 13. Note that the program of the above-described imaging method can be stored in a storage medium such as a disk or a floppy and supplied to the X-ray imaging apparatus.

1 is a system configuration diagram of an X-ray imaging apparatus according to Embodiment 1. FIG. It is a block circuit block diagram. FIG. 3 is an operation flowchart of the first embodiment. It is a schematic diagram of a X-ray generation part. It is explanatory drawing of the state in which the X-ray irradiation area | region is included in the X-ray sensor. It is explanatory drawing of the state where an X-ray irradiation area | region is not included in an X-ray sensor. FIG. 6 is an operation flowchart of the second embodiment. It is explanatory drawing of the square for position determination of Example 3. FIG. It is explanatory drawing in the case of mismatching of an X-ray irradiation area | region and a sensor surface.

Explanation of symbols

11 rounds 12 X-ray generation unit 13 X-ray sensor 14 display unit 15 foot pedal 21 control unit 22 irradiation field recognition unit 23 position determination unit 24 X-ray diaphragm T X-ray irradiation region

Claims (7)

  An X-ray imaging apparatus for forming an X-ray image by detecting an X-ray source for irradiating X-rays and an X-ray irradiated from the X-ray source by a flat detector, An irradiation field recognizing unit for recognizing, a position determining unit for determining a positional relationship between the X-ray source and the flat panel detector based on the X-ray irradiation area recognized by the irradiation field recognizing unit, and a determination by the position determining unit And an X-ray imaging apparatus characterized by comprising control means for controlling an X-ray imaging operation based on the result.   The X-ray imaging apparatus according to claim 1, wherein the control unit controls the X-ray fluoroscopic imaging based on a result of the position determination.   The X-ray imaging apparatus according to claim 1, wherein the control unit stops X-ray fluoroscopic imaging during X-ray fluoroscopic imaging based on the result of the position determination.   The X-ray imaging apparatus according to claim 1, wherein the position determination unit determines whether or not the recognized X-ray irradiation region is included in a surface of the flat detector.   The X-ray irradiation area according to claim 1, wherein the position determination means performs position determination of the recognized X-ray irradiation area using an area set inside a certain distance of the flat panel detector. Line image photographing device.   A step of irradiating X-rays from an X-ray source, a step of forming an X-ray image by detecting the irradiated X-rays with a flat detector, a step of recognizing an X-ray irradiation region irradiated with X-rays, And a step of determining a positional relationship between the X-ray source and the flat panel detector based on the recognized X-ray irradiation region, and a step of controlling an X-ray imaging operation based on the determined result. X-ray imaging method.   A storage medium storing a program for carrying out the photographing method according to claim 6.

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