JP4519887B2 - X-ray imaging apparatus and imaging method - Google Patents

Description

  The present invention relates to an X-ray imaging apparatus and an imaging method for performing X-ray imaging.

  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 and the like. 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, and the X-ray photographic film is exposed to form an X-ray image. Interpretation of this film is carried out by using an observation device called Schaukasten.

  Further, an X-ray TV apparatus that performs fluoroscopic imaging for displaying an X-ray fluoroscopic image on a CRT using an image intensifier as in Patent Document 1 is also widely used in the medical field.

  In recent years, as shown in Patent Document 2, a high-resolution solid-state X-ray detector using an FPD (Flat Panel Detector) has been proposed. This realizes a method of obtaining an X-ray image of a subject as digital data by arranging the subject between an X-ray source and an X-ray detector and converting the X-ray dose transmitted through the subject into an electrical signal. .

  Recently, as shown in Patent Document 3, a cassette type sensor capable of photographing with a sensor unit as a portable type has been put into practical use. On the other hand, 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.

  Patent Document 4 proposes a method of easily determining an imaging position by transmitting an electromagnetic wave from the X-ray generator side to a flat detector.

JP-A-5-64081 Japanese Patent No. 3066944 JP 2004-73354 A Japanese Patent No. 3624106 "JIS Handbook 2005 Radiation (Noh)", C 0601-1-3 Medical Electrical Equipment Japan Standards Industry Association

  FIG. 16 shows a schematic diagram of 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 arranged at a predetermined position, and an object is arranged on the flat detector 1 to perform X-ray imaging.

  At that time, the relationship between the X-ray irradiation region T 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 main 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 X-ray sensor 13.

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

  However, in Patent Document 4, although the position of the flat detector 1 can be detected, since there is no means for controlling X-ray imaging, even if all the irradiated X-rays are not irradiated to the flat detector. There is a problem that X-ray exposure is possible.

  Similarly, in the invention of Patent Document 3, there is no means for controlling X-ray imaging, and the positional relationship between the X-ray source and the flat detector is not taken into consideration, and the position where all the X-rays are not irradiated to the flat detector. Even if it is a relationship, there exists a problem of irradiating fluoroscopic X-rays.

  Moreover, even if there is a positional relationship in which all the X-rays irradiate the flat detector, the positional relationship is such that all the X-rays do not irradiate the flat detector for some reason and the X-rays leak. However, there is a problem of continuing to irradiate fluoroscopic X-rays.

  An object of the present invention is to provide an X-ray imaging apparatus and an imaging method for solving the above-described problems and controlling an X-ray imaging operation based on a positional relationship between an X-ray source and a flat panel detector.

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, X-rays irradiated from the X-ray sources are detected, and an X-ray image is obtained. an X-ray imaging device having a detector formed to, the positional relationship of the detected positional relationship by the position detecting means and said position detecting means for detecting in the X-ray imaging of the detector and the X-ray source And a control means for controlling the exposure of the X-ray source .

The technical features of the X-ray imaging method according to the present invention include a step of irradiating an X-ray with an X-ray source, a step of detecting the irradiated X-ray with a detector to form an X-ray image, and the X A position detection step of detecting a positional relationship between the radiation source and the detector during X-ray imaging , and a control step of controlling the exposure of the X-ray source based on the positional relationship detected in the position detection step. Is to have.
Further, the technical feature of the control device of the X-ray imaging apparatus according to the present invention is to form an X-ray image by detecting an X-ray source for irradiating the X-ray and the X-ray irradiated from the X-ray source. A control device for an X-ray imaging apparatus having a detector, comprising: position detection means for detecting a positional relationship between the X-ray source and the detector during X-ray imaging, detected by the position detection means The exposure of the X-ray source is controlled based on the positional relationship.

  According to the X-ray imaging apparatus and the imaging method according to the present invention, only when it is ensured that the positional relationship between the X-ray source and the flat panel detector is in a position for irradiating the flat panel detector with all irradiation X-rays. Shooting can be performed.

  Further, even before the fluoroscopic imaging, the fluoroscopy can be prohibited when the positional relationship that irradiates the flat detector with all irradiated X-rays is broken.

  Furthermore, when all the X-rays are not incident on the flat detector during X-ray fluoroscopy, it is possible to prevent unnecessary X-ray irradiation and exposure by stopping the X-ray exposure.

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

  FIG. 1 shows a system configuration diagram of an X-ray imaging apparatus mounted on a round wheel. A movable round wheel 11 is provided with an X-ray generator 12 and an X-ray sensor 13, and the X-ray sensor 13 has a cable. Via a control unit (not shown) in the round-wheel 11.

  The X-ray generation unit 12 includes an X-ray tube that irradiates X-rays, an X-ray diaphragm, and a movement detection sensor 14, and the X-ray sensor 13 receives the X-rays irradiated by the X-ray generation unit 12 and outputs image signals. It is a sensor to be acquired and includes a movement detection sensor 15. The X-ray generator 12 is attached with one electromagnetic wave transmitter, and the X-ray sensor 13 is attached with at least three electromagnetic wave receivers.

  Further, the round wheel 11 is provided with a display unit 16 for displaying an image taken by the X-ray sensor 13. The display unit 16 includes 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. Further, a foot pedal 17 for instructing X-ray irradiation and stopping is connected to the control unit via a cable outside the round-wheel 11.

  Note that, in addition to the foot pedal 17, the X-ray imaging apparatus includes general input devices such as a keyboard and a mouse (not shown), and is provided with a mechanism for inputting a user's operation.

  FIG. 2 shows a block circuit configuration diagram of the X-ray imaging apparatus. An X-ray generation unit 12, an X-ray sensor 13, movement detection sensors 14 and 15, a foot pedal 17, and a position determination unit 22 are connected to the control unit 21. The control unit 21 is a control unit that performs various controls on the X-ray generation unit 12 and the X-ray sensor 13, and is disposed in the casing of the round-wheel 11 together with the position determination unit 22.

  The control unit 21 and the position determination unit 22 are configured as functions by executing a program of a CPU (Central Processing Unit) (not shown), and the CPU can also be configured by an LSI, an ASIC, or the like.

  FIG. 3 is an operation flowchart in the present embodiment. First, in step S101, an electromagnetic wave is transmitted from the electromagnetic wave transmitter provided in the X-ray generator 12, and in step S102, the electromagnetic wave receiver provided in the X-ray sensor 13 receives the electromagnetic wave. There are three or more electromagnetic wave receivers, and the distance between the focal point of the X-ray generator 12 and the X-ray sensor 13 is measured based on the delay time of the electromagnetic wave reception time from the electromagnetic wave transmitter. The number of the electromagnetic wave transmitters is not necessarily one, and a plurality of electromagnetic wave transmitters may be used.

  Next, the position is determined by the position determination unit 22 in step S103. In this position determination, it is determined whether or not the X-ray generation unit 12 and the X-ray sensor 13 are at the opposite positions from the delay time related to reception of the electromagnetic wave transmitted and received in steps S101 and S102. Here, being in the facing position is assumed to be in the facing position when all the X-rays irradiated from the X-ray generation unit 12 are irradiated into the X-ray sensor 13.

  As a condition at the facing position, the X-ray irradiation region T is required to be included in the X-ray sensor 13. For example, FIGS. 4A to 4L show patterns of the positional relationship between the X-ray sensor 13 and the X-ray irradiation region T. FIG. In the pattern of FIG. 4 (k), the X-ray generation unit 12 and the X-ray sensor 13 are at opposite positions, and the X-ray irradiation region T is included in the X-ray sensor 13.

  Here, when the X-ray irradiation region T is exceptionally square, there may be a case where the X-ray sensor 13 has an opposing relationship even when three vertices are included in the X-ray sensor 13. Further, since the X-ray source is the same as the point light source, the irradiated X-rays diffuse with the distance. That is, when the distance between the X-ray generation unit 12 and the X-ray sensor 13 is too long, the X-ray irradiation region T may not be accommodated in the X-ray sensor 13 due to the influence of X-ray diffusion.

  FIG. 5 shows an example in which the X-ray irradiation region T is within the X-ray sensor 13 because the distance between the X-ray generator 12 and the X-ray sensor 13 is relatively short. On the other hand, in FIG. 6, the distance between the X-ray generation unit 12 and the X-ray sensor 13 is farther than in the case of FIG. 5, so that the X-ray irradiation region T does not fit within the X-ray sensor 13. In these cases, FIG. 5 can be said to be in an opposing relationship, but FIG. 6 cannot be said to be in an opposing relationship.

  For example, as shown in FIG. 7, when the electromagnetic wave receivers 1 to 4 are attached to fixed positions on the surface of the X-ray sensor 13, the distances between the electromagnetic wave transmitters and the electromagnetic wave receivers 1 to 4 are estimated. If possible, the spatial positional relationship between the X-ray generator 12 and the X-ray sensor 13 is uniquely determined. Moreover, since the propagation speed of electromagnetic waves is known in advance, the distance between the X-ray generator 12 and the X-ray sensor 13 can be estimated from the difference between the transmission time and the reception time.

  As shown in FIG. 8, an electromagnetic wave is transmitted from the electromagnetic wave transmitter at a timing t and received by each of the electromagnetic wave receivers 1 to 4. The reception timings are t1, t2, t3, and t4, respectively. However, if the reception timings t1 to t4 are all equal, it can be said that the main axes of the X-ray generator 12 and the X-ray sensor 13 are the same.

  FIG. 9 is a schematic diagram of the X-ray generation unit 12. Normally, the irradiation angle θ of the X-ray generation unit 12 is predetermined by the opening. In other words, an X-ray diaphragm 31 is provided on the emission side of the X-ray generator 12, and the X-ray irradiation area can be freely changed by adjusting the opening / closing of the X-ray diaphragm 31. Accordingly, the adjustment of the X-ray diaphragm 31 changes the X-ray irradiation target angle and the shape of the X-ray irradiation region T in various ways. This shape can also be calculated from the X-ray diaphragm amount. Depending on the shape of the X-ray diaphragm 31, the X-ray irradiation region T may have a hexagonal shape, an octagonal shape, or a circular shape depending on the shape of the X-ray diaphragm 31.

  As described above, the spatial positional relationship between the X-ray generator 12 and the X-ray sensor 13 is uniquely determined from the electromagnetic wave transmission / reception time. Therefore, the X-ray irradiation angle is estimated based on the X-ray aperture information, and it is estimated whether the X-rays emitted from the X-ray generation unit 12 are all disposed in the X-ray sensor 13. The facing position can be obtained.

  Next, in step S104 in FIG. 3, when it is determined that the determination result by the position determination unit 22 in step S103 is in the opposite position, X-ray fluoroscopic imaging is permitted. To permit fluoroscopic imaging, the mode may be automatically shifted to the fluoroscopic mode, or may be in a state where it is possible to simply shift to the fluoroscopic mode. At this time, the X-ray generator 12 and the X-ray sensor 13 may be locked so as not to move. Here, the fluoroscopic mode refers to a shooting technique that is taken continuously other than one still image shooting in a broad sense. For example, cine shooting for the purpose of storing an image, contrast contrast imaging called DSA, or the like. Etc. are also included.

  Subsequently, in step S105, the machine waits for detection of machine movement. For detection of machine movement, movement is detected by a movement detection sensor 14 attached to the X-ray generation unit 12 and a movement detection sensor 15 attached to the X-ray sensor 13. Furthermore, in addition to detecting the opening / closing operation of the X-ray diaphragm 31 of the X-ray generation unit 12 as a movement, a method of detecting a moving body disclosed in Patent Document 3 may be used.

  As the movement detection sensors 14 and 15, inertia sensors are used, but other known angle sensors, speed sensors, and linear sensors, for example, may be used. Note that these sensors are used to detect movement, and it goes without saying that a plurality of sensors may be used, or a plurality of types of sensors may be used in combination.

  When it is determined that there is a mechanical movement based on the detection result using the movement detection sensors 14 and 15 in the fluoroscopic imaging enabled state, it is determined in step S106 whether the imaging apparatus is currently being fluoroscopic. If fluoroscopic imaging is being performed, first, fluoroscopic imaging is disabled in step S107. As a method for making it impossible, there is a method in which the control unit 21 controls to immediately stop the X-ray irradiation. However, there is no problem even if the stop is stopped after a certain period of time. When fluoroscopic imaging is stopped, step S108 is performed. Also, if it is not determined in the step S106 that the fluoroscopy is in progress, the process of the step S108 is similarly performed.

  In step S108, fluoroscopic imaging is prohibited. Prohibition of fluoroscopic imaging is a method for preventing the user from selecting a fluoroscopic imaging mode on the GUI, a method for preventing the control unit 21 from performing a fluoroscopic operation even when there is a request for fluoroscopy from the outside to the control unit 21, There is a method of cutting off the power.

  FIG. 10 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 contents. In the first embodiment, fluoroscopic imaging is prohibited immediately or after a certain time when mechanical movement is detected in step S105.

  In the second embodiment, steps S101 to S103 are the same as those in the first embodiment. In step S201, the X-ray irradiation region T is stored as position information from the target angle of X-ray irradiation in step S103, the X-ray aperture position, and the distance and position between the X-ray focal point and the X-ray sensor 13. For example, information on which region of the X-ray sensor 13 is irradiated with the X-ray irradiation region T is stored.

  After that, when machine movement is detected in step S105 through step S104, the extent to which the X-ray irradiation region T changes is estimated based on information from the movement detection sensors 14 and 15. In step S202, the estimation result and the position information stored in step S201 are compared and updated to determine the facing position. For example, since the X-ray irradiation region T on the X-ray sensor 13 has been estimated in advance, a new amount on the X-ray sensor 13 can be obtained by obtaining a relative movement amount between the X-ray generation unit 12 and the X-ray sensor 13. The X-ray irradiation region T becomes clear and the facing position can be determined.

  As a result of determining the facing position, if the X-ray irradiation region T is included in the X-ray sensor 13 even after the machine movement, the position information after the machine movement is stored in step S203, and the fluoroscopic permission is continued. The process proceeds to S105. On the other hand, if the X-ray irradiation region T is not included in the X-ray sensor 13 after the machine movement, the process proceeds to step S106.

  FIG. 11 is an operation flowchart of the third embodiment, and the same step numbers as those in the first and second embodiments indicate the same processing contents. In the second embodiment, the position information collected at the time of position determination in step S103 is stored in step S201, and when the machine movement is detected in step S105, the facing position is determined from the position information and the machine movement amount.

  In the third embodiment, when mechanical movement is detected, the electromagnetic wave is transmitted again in step S301, the electromagnetic wave transmitted in step S302 is received, and the position determination is performed by the same processing as the position determination performed in step S103. .

  In the operation flowchart of FIG. 11, it is described that transmission and reception of electromagnetic waves are performed before position determination, but position determination may be performed by continuously transmitting and receiving electromagnetic waves.

  FIG. 12 is a block circuit configuration diagram of the fourth embodiment. Compared with FIG. 2, an irradiation field recognition unit 41 is connected to the control unit 21.

  In the fourth embodiment, in the position determination in step S103 in the first to third embodiments, the position is determined by transmitting an electromagnetic wave in step S101 and receiving the electromagnetic wave in step S102. FIG. 13 is a flowchart of the operation of the portion, and still image shooting is executed in step S401, and position determination is performed by executing irradiation field recognition in step S402.

  In the still image shooting in step S401, the X-ray sensor 13 receives the X-rays emitted from the X-ray generation unit 12 under the control of the control unit 21, and is imaged. The irradiation field recognition performed in step S402 is a known technique that is processed by the irradiation field recognition unit 41 and extracts the X-ray irradiation region T irradiated to the X-ray sensor 13 by performing image analysis processing. By performing this irradiation field recognition, the X-ray irradiation region T irradiated on the X-ray sensor 13 can be known.

  Next, in the position determination in step S103, the position determination is performed using the irradiation field recognition result extracted in step S402. 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. 14 shows an example where the X-ray irradiation region T is included in the X-ray sensor 13. None of the sides around the X-ray sensor 13 intersect with the sides around the X-ray irradiation region T. If no X-rays are incident on the X-ray sensor 13, the irradiation field recognition unit 41 cannot recognize the irradiation field, resulting in an error.

  On the other hand, if any of the sides around the X-ray sensor 13 and the sides around the X-ray irradiation region T intersect, the X-ray irradiation region S irradiated to the X-ray sensor 13 is included in the X-ray sensor 13. Judge that it is not.

  FIG. 15 shows an example in which the X-ray irradiation region T 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, the X-ray irradiation region T is an X-ray when there is no side where the peripheral side of the X-ray irradiation region T extracted in step S402 coincides with the peripheral side of the X-ray sensor 13. It is determined that it is within the 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 same processing as in the first to third embodiments in step S104 is performed, and the X-ray irradiation region T is changed to the X-ray irradiation region T. If it protrudes outside the line sensor 13, it returns to the initial state.

  Note that the still image shooting in the fourth embodiment means one image, and it is sufficient if an image that can be recognized by the irradiation field is obtained. Therefore, the X-ray condition may be a normal still image shooting condition, or there is no problem even if the X-ray condition at the time of fluoroscopy is used.

  In addition, about the imaging | photography method of this invention, the program can also be memorize | stored in storage media, such as a disk and a floppy, and can also be supplied to an X-ray imaging apparatus.

1 is a system configuration diagram of an X-ray imaging apparatus according to an embodiment. It is a block circuit block diagram. FIG. 3 is an operation flowchart of the first embodiment. It is a related figure of an X-ray sensor and an X-ray irradiation area. It is explanatory drawing of the state which a X-ray irradiation area | region fits in a X-ray sensor surface. It is explanatory drawing of the state from which an X-ray irradiation area | region does not fit in an X-ray sensor surface. It is a conceptual diagram of an electromagnetic wave transmitter receiver. It is an electromagnetic wave transmission / reception timing diagram. It is a schematic diagram of a X-ray generation part. FIG. 6 is an operation flowchart of the second embodiment. FIG. 10 is an operation flowchart of the third embodiment. 6 is a system configuration diagram of an X-ray imaging apparatus according to Embodiment 4. FIG. FIG. 10 is an operation flowchart of the fourth embodiment. It is explanatory drawing of the state in which an X-ray irradiation field fits in an X-ray sensor surface. It is explanatory drawing of the state which an X-ray irradiation field does not fit in an X-ray sensor surface. It is explanatory drawing of mismatching of a X-ray irradiation area | region and a sensor surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Round-trip vehicle 12 X-ray generation part 13 X-ray sensor 14, 15 Movement detection sensor 16 Display part 17 Foot pedal 21 Control part 22 Position determination part 31 X-ray diaphragm 41 Irradiation field recognition part T X-ray irradiation area | region

Claims (11)

An X-ray imaging apparatus having an X-ray source for irradiating X-rays and a detector for detecting X-rays emitted from the X-ray source and forming an X-ray image, the X-ray source and A position detection unit that detects a positional relationship with the detector during X-ray imaging , and a control unit that controls the exposure of the X-ray source based on the positional relationship detected by the position detection unit. A featured X-ray imaging apparatus. The position detection means detects movement of at least one of the X-ray source and the detector, and the control means stops exposure of the X-ray source when movement is detected by the position detection means. The X-ray imaging apparatus according to claim 1. If the control means is a positional relationship X-rays detected positional relationship by said position detecting means is irradiated from the X-ray source is irradiated to all the detectors, to continue the exposure of the X-ray source The X-ray imaging apparatus according to claim 1 . If the control means is not positional relationship X-rays detected positional relationship by said position detecting means is irradiated from the X-ray source is irradiated to all the detectors, to stop the irradiation of the X-ray source The X-ray imaging apparatus according to claim 1 , wherein: The X-ray source having electromagnetic oscillator, said detector having the electromagnetic receiver, the position detecting means by receiving electromagnetic waves emitted from the electromagnetic wave oscillator by the wave receiver, the X-ray The X-ray imaging apparatus according to any one of claims 1 to 4, wherein movement of at least one of a source and the detector is detected. At least one of the X-ray source and the detector has an inertial sensor, and the position detection means detects movement of at least one of the X-ray source and the detector based on an output result of the inertial sensor. The X-ray imaging apparatus according to any one of claims 1 to 4, wherein: It has irradiation field recognition means for recognizing an X-ray irradiation area on the detector, and the position detection means detects the positional relationship between the X-ray source and the detector based on the recognition result of the irradiation field recognition means. The X-ray imaging apparatus according to any one of claims 1 to 4 , characterized in that : The step of irradiating the X-ray with the X-ray source, the step of detecting the irradiated X-ray with a detector to form an X-ray image, and the positional relationship between the X-ray source and the detector during X-ray imaging position detection step and, X-rays imaging method characterized by a control step of controlling the exposure of the X-ray source based on the positional relationship detected by the said position detection step of detecting. A storage medium storing a program for executing the X-ray imaging method according to claim 8 . A control device for an X-ray imaging apparatus, comprising: an X-ray source for irradiating X-rays; and a detector that detects X-rays emitted from the X-ray source and forms an X-ray image, A position detecting means for detecting the positional relationship between the source and the detector during X-ray imaging, and controlling the exposure of the X-ray source based on the positional relationship detected by the position detecting means. A control device for an X-ray imaging apparatus.   The storage medium which memorize | stored the program which functions the control apparatus of the X-ray imaging apparatus of Claim 10.