JP2017029690A - Collimator device, radiation therapy system using the same, control method and program - Google Patents

Abstract

High-precision radiation irradiation is performed while tracking a moving object at high speed with a small and lightweight apparatus configuration. In a radiotherapy system having an electron gun that generates an electron beam and a target that converts the generated electron beam into radiation, the target 4 is disposed inside the radiation treatment system, and the radiation leaks to the outside. And a second collimator arranged in a state having a gap in the first collimator and passing radiation in the axial direction of the first collimator. Rotate the collimator. [Selection] Figure 2

Description

  The present invention relates to a collimator device for irradiation radiation and a radiation therapy system using the same.

  In radiation (for example, X-ray) treatment, when X-rays are irradiated to the affected area that is the irradiation target, abnormal cells such as cancer cells can be accurately irradiated with X-rays, while normal cells can be irradiated. It is necessary to avoid X-ray irradiation as much as possible. However, there are various forms of cancer that occurs in the human body, and because the human being who is the target of X-ray irradiation is a living body, even when resting in a lying state, etc., weak body movement (body Move). This body movement is based on the movement of the internal organs such as the lungs and the heart (breathing, heartbeat, etc.).

  As a configuration for performing “moving body tracking” to follow such a moving organ, an X-ray generation unit that generates X-rays and an X-ray collimator are moved to follow the X-ray irradiation field to the affected body movement. What was made to think was thought. Patent Document 1 states that “a linear detector that detects transmitted X-rays transmitted through an affected area of a patient is moved and a movable collimator that restricts an X-ray irradiation field is moved to transmit transmitted X-rays to the linear detector. A "radiotherapy apparatus limited to a detection width" is disclosed. In Patent Document 2, “first and second localization method (orientation radiotherapy method) collimator leaves having oblique slit holes are attached to an irradiation field forming collimator, and the first and second localization methods are used. There has been disclosed a stereotactic radiotherapy apparatus in which the position of a collimated hole formed at the intersection of slit holes is controlled by the movement of a collimator. These are devices in which a necessary irradiation field is obtained by appropriately moving and controlling a pair of left and right collimators.

  Patent Document 3 states that “an apparatus including a gantry arm in which an electron beam generation source and a deflecting electromagnet are coupled by a vacuum rotary joint to hold an irradiation head including a target and a collimator, and is parallel to the rotation axis of the gantry arm. Rotating means for swinging the irradiation head about the axis passing through the virtual source position is provided, and the variable aperture device can be moved in an arc shape centering on the source position in the traveling direction of the electron beam. A radiotherapy apparatus provided with means for performing the above-mentioned is disclosed. According to this apparatus, the irradiation head swings and rotates around an axis parallel to the rotation axis of the gantry arm, and the collimator moves in the gantry arm rotation axis direction, so that the diaphragm is controlled to move in two directions. . As a result, it is possible to appropriately irradiate the patient's body movement with X-rays.

  Patent Document 4 and Patent Document 5 describe that “a therapeutic X-ray generation source is fixed to a support base (gimbal mechanism) via a rotation mechanism having two rotation axes orthogonal to each other, and the above-mentioned therapeutic X-ray generation is performed. The X-ray emitted from the source is controlled by the rotation mechanism so that the irradiation axis faces the isocenter, and the therapeutic X-ray generation source is separated from the support table via the positioning mechanism. Thus, a radiation irradiation apparatus whose position is adjusted in two axial directions is disclosed. According to this apparatus, the X-ray irradiation axis and the central axis of the collimator fixed to the support base are controlled to be isocentered by adjusting the rotation mechanism and the positioning mechanism. Can be applied to the affected area.

  However, according to the devices described in Patent Document 1 and Patent Document 2, the pair of left and right collimators are simply controlled to move in one direction, taking into consideration the high speed of collimator movement, the required irradiation field formation accuracy, and the like. It was not a device. According to the apparatus described in Patent Document 3, the gantry arm provided with the electron beam generation source and the irradiation head provided with the target and the collimator are coupled by the vacuum rotary joint. There is a considerable amount of mechanical instability in the X-ray irradiation system due to “tack” and the like. Also, since the center position of the swing motion for swinging the irradiation head and the movement center position of the collimator in the irradiation head are separated, a very high mechanical accuracy is required to form the required irradiation field. Is required. Further, since the irradiation head including the deflection electromagnet, the target, the collimator, and the like is heavy, it is difficult to realize high speed. Considering the above, according to these conventional techniques, it is difficult to perform “moving object tracking” even if two-dimensional swinging is performed.

  According to the devices described in Patent Document 4 and Patent Document 5, the entire therapeutic X-ray generation source that emits therapeutic radiation rotates its X-ray irradiation axis about two axes to control the directivity angle. It is composed of a “gimbal structure” that can be used, and the scale of the device is large and the weight of the device is very heavy. For this reason, it is difficult to realize high-speed directivity control, and it is difficult to perform moving object tracking at high speed.

  The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide a collimator configuration that enables high-precision radiation irradiation while tracking a moving object at high speed, and an application technique thereof.

To achieve this purpose, the collimator device
A first collimator which arranges a target for converting an electron beam generated from an electron beam source into radiation and suppresses leakage of the radiation to the outside;
A second collimator disposed in the first collimator with a gap and passing the radiation in the axial direction of the first collimator,
The second collimator is slid in the first collimator.

  According to the present invention, high-precision radiation irradiation can be performed while tracking a moving object at high speed.

It is typical explanatory drawing of the process procedure outline | summary using the radiotherapy system 1 grade | etc.,. 2 is a schematic configuration diagram of a main part of an X-ray head 100. FIG. It is a typical block diagram of an X-ray production | generation part. 3 is a schematic configuration diagram of a swing angle detection unit 30. FIG. It is a basic block diagram of the control part of head swing control. It is explanatory drawing of FB control in a head swing operation | movement. It is a block diagram of the detailed example of the control part of head swing control. 1 is a front view of an X-ray irradiation apparatus incorporating an X-ray head 100. FIG. 1 is a perspective view of an X-ray irradiation apparatus incorporating an X-ray head 100. FIG. 1 is a plan view of an X-ray irradiation apparatus incorporating an X-ray head 100. FIG. It is XX sectional drawing of FIG. It is XX sectional drawing at the time of swinging upward. It is XX sectional drawing at the time of swinging in the downward direction. It is explanatory drawing of a head swing operation | movement. It is a typical explanatory view of the appearance of a radiation therapy system. It is a typical explanatory view of an X-ray image imaging principle and an X-ray transmission image. It is explanatory drawing of arrangement | positioning of an imager. It is a figure explaining the new coordinate system for X-ray irradiation position determination. It is a figure which shows the structural example using the swing-angle detector of an encoding system. It is a figure which shows the positional relationship of a linear encoder and a voice coil motor. It is an enlarged view of a linear encoder. It is a figure explaining the detection of the swing angle based on the sensor information of a linear encoder. It is a figure which shows the structural example using a 3rd collimator. It is a figure which shows the state which inserted the 3rd collimator inside the 2nd collimator. It is a hardware block diagram of the control system which performs head swing drive control. It is a basic flow of swing operation control of a collimator. It is a flowchart which shows the specific example of step S13 of FIG.

Before describing the specific configuration of the embodiment, features of the present invention will be briefly described.
(1) A collimator apparatus according to an embodiment includes a first collimator (3) that suppresses leakage of the radiation to the outside by arranging a target (4) that converts an electron beam generated from an electron beam source into radiation. 10) and
A second collimator (20) that is disposed in the first collimator (10) with a gap (OP) and allows the radiation to pass in its axial direction,
The second collimator is swung within the first collimator.

  A general electron gun or the like may be used as the “electron beam source”. The electron beam is accelerated using an accelerating tube or the like and collides with a “target” to generate radiation such as X-rays. At this time, the electron beam is accelerated by introducing high-frequency electromagnetic waves generated by a magnetron or the like into the accelerating tube.

  The second collimator is disposed inside the first collimator with a gap between the second collimator and the inner wall of the first collimator, and the second collimator is swung using the gap to move the object. Irradiation is performed so as to scan.

  The second collimator narrows the radiation to form a required irradiation field, and the first collimator suppresses the generated radiation from leaking to the outside. In addition, the entire collimator apparatus is not swung, but only the second collimator is swung within the first collimator, so that a high-speed swing operation is possible. As a result, X-ray irradiation can be continuously performed following the affected body motion, and highly accurate moving body tracking is possible.

You may use the 3rd collimator inserted in the inside of the 2nd collimator so that exchange is possible. By inserting the third collimator into the second collimator in a replaceable manner, the irradiation field can be adjusted or narrowed to a desired shape. By fitting the third collimator into the collimator space of the second collimator, the third collimator swings integrally with the second collimator as the second collimator swings.
(2) The collimator device has a drive mechanism (25) for swinging the second collimator in two directions, and drive mechanism control means for controlling the drive mechanism. As a result, an irradiation field can be formed at a desired position. Since the drive mechanism can cope with various patterns of the irradiation field, it is preferable that the second collimator is configured to swing in at least two orthogonal directions.
(3) It is preferable that the target (4) exists on the axis of the second collimator. Since the target is always present on the axis of the second collimator, it is possible to accurately irradiate the affected area with radiation. For example, the irradiation field shape, irradiation direction, irradiation dose, and the like can be made desired.
(4) The collimator device includes displacement amount detection means (30A, 30B) for detecting a displacement amount from a reference position of the second collimator, and the drive mechanism control means is detected by the displacement amount detection means. The drive mechanism can also be controlled based on the amount of displacement. Here, the displacement is an angle, a distance, or the like.

According to this configuration, since the drive mechanism control unit controls the drive mechanism based on the displacement amount detected by the displacement amount detection unit, the displacement operation from the reference position of the second collimator is fed back to swing the head. Control can be performed stably. An autocollimator or an encoder sensor can be used as the displacement amount detecting means.
(5) The collimator device is configured to emit visible light together with radiation by matching the optical axis of the visible light laser provided on an appropriate member coupled to the second collimator with the axial center of the second collimator. An optical system that leads to the outside may be provided. According to this configuration, since the optical axis of the optical laser is aligned with the axis of the second collimator in the optical system and the coaxial beam is guided to the outside of the apparatus, for example, red visible light is reflected on the axis of the second collimator. It is possible to visually grasp the incident position of the radiation irradiated to the affected part through the heart on the affected part surface.
(6) The drive mechanism may include a voice coil motor (150a, 150b, 150c, 150d). According to this configuration, since the drive mechanism having the voice coil motor swings the second collimator, it is possible to perform a swing operation with high accuracy at high speed.
(7) In the collimator device, a dosimeter, for example, an ion chamber (27) can be provided on the radiation output side of the second collimator in order to measure the radiation dose and the irradiation direction. According to this configuration, since the ion chamber for measuring the radiation dose is provided on the radiation emission side, it is possible to measure the dose while the second collimator swings. It is also possible to measure the radiation direction with reference to the dose distribution and the like.
(8) It is preferable that the rotation center of the swing motion of the swing portion formed by the second collimator and the components attached thereto is substantially coincident with the center of gravity of the swing portion. Since the center of rotation of the swing motion of the swing portion and the center of gravity of the swing portion substantially coincide with each other, the swing portion does not swing freely by the action of acceleration including gravity. In addition, when the radiotherapy apparatus is mounted on a 6-axis manipulator, even if the 6-axis manipulator moves, it is difficult for the swing portion to swing due to this movement. Here, “substantially coincidence” is intended to include even if it does not coincide completely, and “attached parts” are, for example, “drive mechanism”, “displacement amount detection means”, “ion chamber”, etc. is there.

It is also preferable that the moments of inertia around the swinging rotation center of each part of the swing portion formed by the second collimator and the parts attached thereto are equalized. According to this configuration, since the moment of inertia around the swing rotation center of each component of the swing part is equalized, fluctuations in acceleration torque during acceleration / deceleration when swinging the second collimator are reduced and stable. Sexuality is improved. Here, the attached parts are the same as described above.
(9) The collimator device described above can be applied to a radiation therapy system. In this case, the radiotherapy system uses at least two sets of X-ray tubes that generate X-rays and X-ray detectors that detect the X-rays in a plane, and based on detection signals of the two X-ray detectors. Then, the movement in the vicinity of the affected part in which the marker for attenuating X-rays is previously embedded is specified. According to this configuration, it is possible to accurately obtain body movements in the vicinity of the affected area based on the detection signals of the two X-ray detectors.
(10) Based on the information indicating the motion in the vicinity of the affected area in which the marker is embedded, the drive mechanism control means of the collimator device controls the drive mechanism so that the moving object is tracked in the motion in the vicinity of the affected area in which the marker is embedded. Thus, the second collimator can be swung. Instead of detecting body movement based on the movement of the marker, it is also possible to perform body movement detection by performing image processing (such as contour extraction) on the movement of bones and organs.
(11) In another aspect of the present invention, a radiation therapy system comprises:
An electron beam source (2) that generates an electron beam, a target (4) that converts the electron beam into radiation, and a target (4) that is disposed inside to suppress leakage of the radiation to the outside. One collimator (10), a second collimator (20) which is arranged in a state having a gap in the first collimator and allows the radiation to pass in its axial direction, and the first collimator ( 10) an X-ray head (100) having a swing drive mechanism (25) for swinging the second collimator (20) in 10) and a drive mechanism control means for controlling the swing drive mechanism; a manipulator (200) having an n-axis (n is 6 or more) movable arm (210), and the X-ray head is connected to the tip of the arm.

According to this invention, the manipulator can move, for example, six axes of the arm connected to the tip of the X-ray head, so that the X-ray head can be moved to a desired position at the start of X-ray irradiation or the like. Since exposure to healthy tissue by multi-directional irradiation can be reduced, the number of treatments is reduced and treatment efficiency is improved.
(12) In another aspect of the present invention, a method for controlling a collimator is provided. This control method is
A target that converts an electron beam generated from an electron gun into radiation is disposed inside, and a gap is formed between the first collimator and the first collimator that suppresses leakage of the radiation to the outside. A second collimator that allows the radiation to pass in the direction of its own axis,
In the first collimator, the second collimator is moved toward the target irradiation position of the radiation. Even in this invention, since the second collimator is swung within the first collimator, X-ray irradiation can be continuously performed following the movement of the affected area, and highly accurate moving object tracking is possible. Become.
(13) According to another aspect of the present invention, the target (4) for converting the electron beam generated from the electron gun (2) into radiation is arranged inside itself so that the radiation leaks to the outside. A first collimator (10) to be suppressed, a second collimator (20) which is arranged in a state having a gap in the first collimator and allows the radiation to pass in the axial direction of the first collimator, and the first collimator A drive mechanism (25) for swinging the second collimator (20) in the collimator (10)
A program for realizing the function of controlling the drive mechanism is provided.

  According to this program, a “control function” for controlling a drive mechanism that scans a second collimator that is arranged in the first collimator with a gap and allows radiation to pass in the direction of its own axis is realized. be able to. Since only the second collimator is operated to swing, it can be operated at high speed. By this swinging operation, it is possible to track the moving object while making the irradiation area for the irradiation object a required shape.

  The reference numerals given to the constituent elements of the invention in the embodiment and the like are for the purpose of clarifying the consistency with the embodiment, and do not limit the breadth of the scope of rights.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic explanatory diagram of a radiotherapy procedure using the radiotherapy system 1 of the embodiment. First, an overview of radiation therapy will be described with reference to FIG. 1 to facilitate understanding of the present invention. In the following description, X-rays are taken as an example of radiation.
(Radiotherapy procedure overview)
(A) A marker made of a material that attenuates one or a plurality of radiations, for example, a gold marker G, is implanted in the vicinity of an affected part of a patient P who performs radiation therapy. In the figure, only one marker is shown for convenience. As an example, the gold marker G is a sphere having a diameter of about “1.5 (mm)” manufactured using gold (Au) as a material, and the X-rays are attenuated by the gold marker G and cannot be transmitted. Using this fact, the affected part is specified in the X-ray image. (B) After the fixation of the gold marker G is confirmed, CT imaging of the patient P is performed by a CT (Computer Tomography) apparatus to obtain CT image data.
(C) An X-ray treatment plan for the patient P based on the above CT image data is created by the treatment planning apparatus. Specifically, (C-1) an operator (doctor or the like) inputs an ROI (Region Of Interest: image area of interest) of the affected area and a target dose distribution, and (C-2) treatment planning software The optimum irradiation direction and dose, and the target movement path of the X-ray head 100 (including the main part of the present invention) are calculated. What planned the X-ray irradiation direction, dose, etc. with respect to the affected part of the patient P is an "X-ray treatment plan."
(D) The operator downloads the created treatment plan data to the overall control console of the radiation treatment system 1. (E) Position the patient P on the couch 190. (F) The operator operates the radiotherapy system 1 to irradiate the patient P with therapeutic X-rays. At this time, the X-rays are irradiated with the optimized dose and direction according to the treatment planning apparatus. Specifically, the 6-axis manipulator 200 moves the X-ray head 100 to a designated position, and further, “movement of the patient (affected area) surface, heartbeat, and breathing phase” are not shown. It is measured by each of the “body surface monitoring camera, heartbeat monitoring device, and respiratory phase monitoring device” and used as calculation processing data for compensation to compensate for the motion of the affected area. (G) The treatment is completed, and the patient P is taken down from the couch 190 and left from the treatment room. The above steps (A) to (G) are the outline of the X-ray treatment procedure.

  In the above-described step (F), there is a body movement of the patient P at the time of irradiation of the affected part with X-rays, so that the affected part is not irradiated with X-rays according to the created X-ray treatment plan. For example, when the patient P has lung cancer and the affected part (lung cancer part) existing in the lung is irradiated with X-rays, the affected part is displaced by respiration, so that the affected part is not accurately irradiated with X-rays. Therefore, in the embodiment, as will be described later with reference to FIG. 2, the second collimator (secondary collimator) 20 included in the X-ray head 100 is arranged in at least one direction in the first collimator (primary collimator) 10. Alternatively, the head is swung in two orthogonal directions (one or two dimensions). Thereby, X-rays are continuously irradiated while following the moving affected area. Since moving body tracking can be performed, accurate X-ray irradiation can be realized.

  At the time of X-ray irradiation, the X-ray head 100 is three-dimensionally moved to an appropriate position by the six-axis manipulator 200 and is directed in an appropriate direction so that the second collimator (secondary collimator) 20 (see FIG. Swing motion (shown). The X-ray head 100 is connected to the tip of the arm 210 of the six-axis manipulator 200. The arm 210 is capable of translational movement in three axial directions and rotational movement around the three axes, and moves the X-ray head 100 to a desired position and directs X-rays emitted from the X-ray head in a desired direction. It is possible. The operation of the six-axis manipulator 200 and the position of the X-ray head 100 are controlled by the control device 120. The control device 120 includes an overall control unit 70 and a subunit controller 80. These control operations will be described later with reference to FIG.

The radiation therapy system 1 includes X-ray tubes 50a and 50b and corresponding FPDs (Flat Panel Detectors) 60a and 60b. The marker position detection X-rays radiated from the X-ray tubes 50a and 50b are detected and converted into digital signals by the corresponding FPDs 60a and 60b, respectively. Although it is desirable that the X-ray emission directions from the two sets of X-ray tubes 50a and 50b are orthogonal, it is not essential. A shadow of a gold marker G that attenuates X-rays is formed on the X-ray detection images of the FPDs 60a and 60b. For example, the center of the shadow of the gold marker G is obtained by image processing or the like, and the body motion position information of the affected part is calculated together with the CT image information. Based on the calculated body motion position information, the second collimator (secondary collimator 20 ) Controls the irradiation field to follow the body movement. Note that the control device 120 in FIG. 1 collectively describes a control device for controlling the operation of the radiation therapy system 1, and includes a control system for the six-axis manipulator 200.
(Configuration of X-ray head 100)
FIG. 2 is a schematic configuration diagram of main parts of the X-ray generation unit and the irradiation field forming unit of the X-ray head 100. At least a part of the X-ray head 100 forms a collimator device 101A. The first collimator (primary collimator 10) has a central axis in the direction indicated by the alternate long and short dash line, and has a symmetrical shape with respect to this axial center (central axis). The accelerating tube 3, the target 4, etc. are provided inside the first collimator (primary collimator 10) so that the axial direction of the first collimator (primary collimator 10) is the traveling direction of the accelerated electron beam. Yes. The central axes of the acceleration tube 3 and the target 4 coincide with the axis of the primary collimator 10. The second collimator (secondary collimator 20) is arranged with a gap (OP) in the first collimator (primary collimator 10), and allows X-rays to pass in the axial direction of the second collimator (secondary collimator 20). In the figure, a thick arrow extending from the target 4 in the horizontal direction of the drawing indicates X-ray radiation. The first collimator (primary collimator 10), the second collimator (secondary collimator 20), and the target 4 are manufactured using a metal material such as tungsten (W), for example.

  A dosimeter for measuring an X-ray dose, for example, an ion chamber 27 is provided on the emission side of the second collimator (secondary comometer 20). An aiming laser unit 5 that outputs laser visible light (for example, red light) is provided on an appropriate member coupled to the second collimator (secondary collimator 20). The traveling direction of the laser visible light emitted from the aiming laser unit 5 is set so as to overlap the X-ray emission direction by an optical system such as the mirror 6 and the mirror 7. Therefore, the incident position of the X-ray can be known by observing the affected surface where the laser visible light is applied.

The swing drive mechanism 25 provided on the movable member MV moves the movable member MV, and swings the second collimator (secondary collimator 20) connected to the movable member MV in the direction indicated by the arrow A. It is assumed that the target 4 exists on the axis of the second collimator (secondary collimator 20). For example, a bearing is provided between the spherical surface of the first collimator (primary collimator 10) having a spherical surface centered on the target 4 and the movable member MV to which the second collimator (secondary collimator 20) is coupled. The bearing is, for example, a coupling member provided with arcuate curved motion bearings in two directions so as to be capable of two-degree-of-freedom operation, and holds a movable member MV and a second collimator (secondary collimator 20 having the target 4 as a rotation center). ) Can be smoothly swung. By controlling the swing drive mechanism 25, it becomes possible to accurately irradiate the affected area with radiation. Further, as an example of the displacement amount detection means, a swing angle detection unit 30A is provided. The swing angle detection unit 30A detects the swing displacement amount (swing angle) of the second collimator (secondary collimator 20) from the reference position and outputs it as swing angle information.
(Swing angle detector 30A)
FIG. 4 is a schematic configuration diagram of the swing angle detection unit 30A. The swing angle detection unit 30 </ b> A includes a detection unit 31 and a reflection mirror 35. The reflection mirror 35 is disposed on the movable member MV as shown in FIG. The laser visible light output from the semiconductor laser 32 in the detection unit 31 is converted into parallel light by the collimator lens 34, passes through the half mirror 36, is reflected by the reflection mirror 35, and is reflected by the half mirror 36 again. The reflected light is focused on a light receiving element 38 such as a CCD by a light receiving lens 37. In FIG. 4, the optical path at the reference time (for example, when the second collimator (secondary collimator 20) is not swung) is indicated by a solid line. On the other hand, when the swing angle detection unit 30 is tilted, that is, when a swing operation is performed, the image formation position on the light receiving element 38 moves as an optical path indicated by a dotted line.

  Specifically, when the swing angle detector 30A is tilted by “α” from the reference angle, the optical path indicated by the dotted line is tilted by “2α” with respect to the optical path indicated by the solid line, and the imaging position on the light receiving element 38 is moved. To do. Then, the signal processing unit 39 processes the signal from the light receiving element 38, calculates the tilt of the swing angle detection unit 30A, and outputs information on the swing angle. Information on the imaging position on the light receiving element 38 corresponding to the inclination of the swing angle detection unit 30A is tabulated in advance, and the swing angle detection is performed based on the reception signal closest to the tabulated information. The inclination of the unit 30A, that is, the swing angle of the second collimator (secondary collimator 20) may be detected and output. Use of this configuration is preferable because the software / hardware configuration of the signal processing unit 39 is simplified. Since the light output from the semiconductor laser 32 is collimated by the collimator lens 34, even if the detection unit 31 moves in the normal direction of the reflection mirror 35, the optical information that has little influence on the image formation information of the light receiving element 38. It is a system. As shown in FIGS. 8, 9, and 10, the detection unit 31 is fixed to the X-ray head base 300 via the bracket 180, and the reflection mirror 35 is provided on the movable member MV (swing base 170 in FIG. 8). Other optical system members (semiconductor laser 32, collimator lens 34, half mirror 36, and light receiving lens 37) and CCD light receiving element 38 may be installed on the built-in housing of X-ray head 100. is there. The latter form has the advantage that the swinging movable part can be light. A CMOS sensor may be used as the light receiving element 38 instead of the CCD.

  Returning to FIG. 2, the electron beam emitted from the electron gun 2 (see FIG. 3) is accelerated by the accelerating tube 3 and collides with the target 4, and as a result, the electron beam is converted into X-rays. The irradiation area of the X-rays generated by the target 4 is narrowed by the second collimator (secondary collimator 20), and a required irradiation field for the affected part can be formed. Furthermore, the X-rays generated by the target 4 can be prevented from leaking to the outside by the first collimator (primary collimator 10).

  By driving and controlling the swing drive mechanism 25, the movable member MV moves in both directions indicated by the arrow A (the vertical direction in the drawing), so the second collimator (secondary collimator 20) swings in the vertical direction in the drawing. I do. A swing displacement amount (swing angle) that is a swing amount from the reference position is detected by the swing angle detection unit 30. For example, the detected swing displacement amount is fed back to perform the swing motion, and the control operation is stabilized. Note that the second collimator (secondary collimator 20) is made perpendicular to the drawing by moving the movable member MV in the front and back direction of the drawing in addition to the vertical swing operation (one-dimensional operation and one-way operation) in the drawing. It is possible to perform the swinging motion in the direction (front and back direction).

That is, the swing operation of the second collimator (secondary collimator 20) in two directions (two dimensions) is possible. This two-dimensional swing drive can also be performed by a swing drive mechanism provided for each direction. Further, the detection / output of the swing displacement amount can be performed by one swing angle detection unit 30 or can be performed by a detection unit provided for each direction. By using, for example, a voice coil motor as the swing drive mechanism 25, a high-speed and high-precision swing operation can be performed. As described above, the X-ray head 100 includes the electron gun 2, the acceleration tube 3, the target 4, the aiming laser unit 5, the first collimator (primary collimator 10), the second collimator (secondary collimator 20), the neck The swing drive mechanism 25, the swing angle detection unit 30, the X-ray head controller 90 (see FIG. 5), and the like are configured as main components.
(X-ray generator)
FIG. 3 is a schematic configuration diagram of the electron beam generation unit, the acceleration unit, and the X-ray generation unit in the X-ray head 100 in particular. The power / control unit 105 supplies power to a required location or gives a control signal. Electron gun driving power is supplied to the electron gun 2, and the inside of the electron gun 2 is made a vacuum atmosphere by driving the ion pump 45. The acceleration tube 3 accelerates the electron beam emitted by the electron gun 2 in the tube. The inside of the acceleration tube 3 is made into a vacuum atmosphere by the operation of the ion pump 43. The steering coil 11 is a coil for applying a magnetic field for finely adjusting the acceleration direction of the electron beam.

  A target 4 is embedded in the vicinity of the end (right side of the drawing) of the accelerating tube 3, and X-rays are generated when an electron beam collides, so that the target 4 serves as an “electron beam-X-ray” conversion means. As described above, the generated X-ray is used as a required irradiation field by the second collimator (secondary collimator 20) that performs the swinging operation. In FIG. 3, the laser visible light output from the aiming laser unit 5 is guided by mirrors 6 and 7 (see FIG. 2), and the X-ray axis (X-ray traveling direction central axis) and the laser beam optical axis (laser beam). The central axis) is shown to overlap. The supply amount of the cooling water from the cooling water distributor 180 is adjusted by a flow rate adjusting valve and supplied to a required location. In particular, cooling water having a constant temperature is supplied to the target 4, the acceleration tube 3, the magnetron 40, the circulator 42, and the like.

  When the magnetron high voltage pulse is supplied to the pulse transformer 154, the high voltage of the pulse transformer 154 is applied to the magnetron 40 via the heater transformer 156, and the magnetron 40 generates and outputs a high frequency electromagnetic wave. The vicinity of the magnetron 40 is made a vacuum atmosphere by the operation of the ion pump 46.

  The electromagnetic wave generated and output by the magnetron 40 passes through waveguide devices such as an E-bend, flexible waveguide, H-bend, circulator 42, H-bend, and coupler 44, and is introduced into the acceleration tube 3 through the RF window 15. The The AFC phase detection unit 152 detects the phase difference between the traveling wave and the reflected wave guided in the waveguide device using the two terminals of the coupler 44, and is connected to the cavity of the magnetron 40. 150 changes the oscillation frequency by controlling the size of the cavity according to the detected phase difference. As a result, AFC (Auto Frequency Control), that is, frequency stability control is performed by feeding back the frequency shift of the high-frequency electromagnetic field.

In the accelerating tube 3, when a high frequency electromagnetic wave is introduced from the RF window 15, an electric field suitable for acceleration is formed along the central axis of the tube, and the electron beam is accelerated. The electron beam output from the electron gun 2 is accelerated by a high-frequency electromagnetic field generated in the acceleration tube 3 and collides with the target 4 to generate X-rays. The publication “JP 2008-198522” published by the applicant of the present application (joint application) describes the principle and the like of such a linac type X-ray generation unit. If the target 4 has a collimator with an X-ray guide hole (hole diameter 0.6 (mm) or less), the spot diameter of the electron beam emitted toward It has been confirmed that small X-rays can be generated.
(Control system configuration)
5 is a basic block diagram of a control unit for swing control of the X-ray head 100, FIG. 6 is a basic principle of swing control, and FIG. 7 is a schematic block diagram of swing control in the radiation treatment system 1 as a whole. As shown in FIG. 5, when the information “θx, θy” indicating the two-dimensional swing angle of the second collimator (secondary collimator 20) is supplied, the X-ray head controller 90 causes the X-axis head swing. Commands are given to the drive mechanism 94 and the Y-axis swing drive mechanism 96. As a result, each of the X-axis direction swing drive mechanism 94 and the Y-axis direction swing drive mechanism 96 has an X-axis direction swing angle and a Y-axis direction swing angle of the second collimator (secondary collimator 20). The drive is controlled so as to be “θx, θy”. This is the basic configuration of the control system.

  As shown in FIG. 6, the voice coil motor driver 92 of the X-ray head controller 90 controls the voice coil motor 150 in accordance with the generated control signal, so that the swinging operation is performed. This swing angle is detected by the swing angle detection unit 30A, and the detected angle is compared with the angle command value given from the subunit controller 80, and feedback control is performed so as to absorb the deviation. With this configuration, control stability is achieved.

  FIG. 7 is a configuration example of a control system of the radiation therapy system 1. The overall control unit 70 includes a tracking controller 71 and a timing controller 72. The timing controller 72 generates a synchronization signal for synchronizing each device in the system and supplies it to the 6-axis manipulator 200, the imager 65, the subunit controller 80, and the like. The imager 65 is a set of the X-ray tube 50 and the FPD 60 shown in FIG. 1 (a set of the X-ray tube 50a and FPD60a and a set of the X-ray tube 50b and FPD60b) for acquiring X-ray images. Device. The tracking controller 71 receives the coordinates (x, y, z, yaw, roll, pitch) of the X-ray head 100 from the 6-axis manipulator 200.

The 6-axis manipulator 200 always operates so that the X-ray head 100 is directed to the isocenter (treatment center). Here, the coordinate system takes the x and y axes in two directions on the plane with the isocenter as the origin, and the Z axis in the vertical direction. “Yaw” is the amount of rotation about the z axis, “roll” is the amount of rotation about the x axis, and “pitch” is the amount of rotation about the y axis. The tracking controller 71 is supplied with the coordinates (x, y, z) of the irradiation target from the imager 65. Then, the subunit controller 80 receives the supply of the swing angle setting information (θx, θy) from the tracking controller 71, and sends the swing angle setting information (θx) to the X-ray head controller 90 built in the X-ray head 100. , Θy).
(Control action)
(1) The tracking controller 71 of the overall control unit 70 receives the coordinates (x, y, z, yaw, roll, pitch) of the X-ray head 100 from the 6-axis manipulator 200. The tracking controller 71 also receives the coordinates (x, y, z) of the irradiation target from the imager 65. The tracking controller 71 calculates and calculates the desired swing angle of the second collimator (secondary collimator 20) based on the received current coordinates and irradiation target coordinates of the X-ray head 100.
(2) The tracking controller 71 of the overall control unit 70 transmits the obtained swing angle as swing angle setting information to the subunit controller 80 of the X-ray generation unit. The subunit controller 80 transmits the received swing angle setting information to the X-ray head controller 90 in the X-ray head 100.
(3) The X-ray head controller 90 receives the swing angle setting information, performs arithmetic processing for feedback control, and passes this to the swing drive mechanism 25 through the driver circuit. The swing drive mechanism 25 drives the second collimator (secondary collimator 20) so that the swing angle is based on the received swing angle setting information. In the figure, the “irradiation field forming section” in the X-ray head 100 is an irradiation field forming function of the first collimator (primary collimator 10), the second collimator (secondary collimator 20), the swing drive mechanism 25, and the like. It is a part which has.

By repeating the above operations (1) to (3), the X-ray axis is always directed to the irradiation target, so even if there is body movement, appropriate X-ray irradiation to the affected area is realized by the collimator swinging operation. it can. In the lower right side of FIG. 7, the X-ray axis follows the collimator swinging motion (vertical direction in the drawing) even if the irradiation target T of the patient P (the affected part that is the irradiation target) moves away from the reference collimator axis. Is indicated by a bold line. Since these series of operations are executed in real time in accordance with the synchronization signal generated and output by the timing controller 72 of the overall control unit 70, it is possible to perform moving body tracking at high speed.
(Image processing)
The image processing operation of the imager 65 will be described with reference to FIGS. FIG. 16A is a principle diagram of X-ray fluoroscopic imaging. In the X-ray transmission image, since there is no difference in contrast between the normal tissue and the cancer affected part, the cancer affected part cannot be directly seen. Therefore, a gold marker G having a diameter of about 1.5 (mm) is inserted in the vicinity of the cancer affected part and observed. Two sets (one set of X-ray tube 50a and FPD 60a and one set of X-ray tube 50b and FPD 60b) are prepared for one set of X-ray tube and FPD (Flat Panel Detector). It is desirable to set the X-ray axes from the X-ray tubes 50a and 50b of each set (the central axis in the X-ray traveling direction) to be orthogonal, but the present invention is not necessarily limited to this example. FIG. 16B is an example of an X-ray image detected by the FPDs 60a and 60b. By analyzing this, the center coordinates of the gold marker G can be obtained in the FPD coordinate system ((η, ξ) coordinate system). Here, a case where image processing is performed using two sets of X-ray tubes and FPD will be described as an example, but more accurate image processing is performed using three or more sets of X-ray tubes and FPD. It is also possible to perform.

  Based on the four coordinates (η1, ξ1) and (η2, ξ2) of the two images, the three-dimensional coordinates (x, y, z) of the center of the gold marker G can be obtained. That is, “(x, y, z) = f (η1, ξ1, η2, ξ2)”. If the function f is appropriately determined and finally adjusted by calibration, the coordinates of the gold marker G can be accurately measured. The information necessary for actual treatment is not the coordinates of the gold marker G but the coordinates of the cancer affected area, but the positional relationship between the gold marker G and the cancer affected area should be determined in advance by a treatment plan using CT images. To. For example, the coordinates (x1, y1, z1) of the cancer affected part are “x1 = x0 + a, y1 = y0 + b, z1 = z0 + c”, etc., with the coordinates of the gold marker G being (x0, y0, z0).

  Below, an example of the calculation algorithm which calculates | requires the coordinate (target coordinate) of the gold marker G using the imager 65 is demonstrated. The basic principle is to obtain position coordinates based on a stereo image obtained by an imager 65 composed of an X-ray tube 50 and an FPD 60. In order to determine this calculation algorithm, the arrangement of the X-ray tubes (50a, 50b) and the FPD (60a, 60b) is important. Specifically, an imager 65 is arranged as shown in FIG. As shown in FIGS. 17A and 17B, the isocenter C of the treatment room is set as the origin, the z axis is taken in the vertical direction, and the x axis and the y axis are taken so as to be orthogonal thereto. The following parameters are important: “Orthogonality”: It is desirable to make the X-ray axis that is a straight line connecting the focal point of the two sets of X-ray tubes (50a, 50b) and the center of the FPD (60a, 60b) orthogonal. “Plane symmetry”: symmetric with respect to the yz plane of the treatment room coordinate system. “Coordinate axis of FPD”: The η axis of the FPD image is an FPD plane intersecting with a plane formed by a pair of X-ray axes, and the ξ axis is also on the FPD plane and is orthogonal to the η axis. “Elevation angle”: An angle formed by the normals of the plane formed by the pair of X-ray axes and the xy plane of the treatment room coordinates is defined as θ, and this is referred to as “imager elevation angle”. “Magnification ratio”: The ratio of the distance from the X-ray generation point of the X-ray tube to the gold marker G and the FPD surface on the straight line connecting the X-ray generation point of the X-ray tube and the gold marker G is “1: α " This is an enlargement ratio on the FPD screen. Orthogonality and plane symmetry are not essential but desirable.

  When the cancer affected part position is an x upper bar, a y upper bar, and a z upper bar, the following expression (1) is obtained.

  The relationship between the coordinates (x, y, z) of the gold marker G in the treatment room coordinate system and the FPD coordinate system [(η1, ξ1), (η2, ξ2)] is based on the coordinate rotation matrix (Rx, Rz). The enlargement factor α is expressed as the following equation (2).

ただし、アイソセンタから金マーカーＧまでの距離（ｘ²＋ｙ²＋ｚ²）^1/2はＸ線管−アイソセンタ、あるいは、ＦＰＤ−アンソセンタ間距離に比べて十分に短いと仮定している。つまり、拡大率αをＸ線管の発生点からアイソセンタまでと、ＦＰＤ中心までの距離の比として近似している。ここで使用している行列は以下の（３）式〜（５）式である。

However, it is assumed that the distance (x ² + y ² + z ² ) ^1/2 from the isocenter to the gold marker G is sufficiently shorter than the distance between the X-ray tube and the isocenter or the FPD and anisocenter. That is, the enlargement ratio α is approximated as a ratio of the distance from the generation point of the X-ray tube to the isocenter and the center of the FPD. The matrices used here are the following formulas (3) to (5).

これらの行列を纏めると以下の（６）式となる。

When these matrices are collected, the following equation (6) is obtained.

従って以下の行列方程式（７）を解けばよいことに帰着する。

Therefore, the following matrix equation (7) should be solved.

ここで観測量（η１、ξ１，η２、ξ２）から未知数（ｘ，ｙ，ｚ）を求めるのであるが、この方程式は未知数が３個で式数が４であるため通常は解が定まらないので、最小二乗法の解を使う。これは正規方程式として知られており、以下の（８）式となる。ここでｘ、ｙ、ｚはそれぞれ最小二乗法の解である。

Here, the unknowns (x, y, z) are obtained from the observed quantities (η1, ξ1, η2, ξ2). Since this equation has 3 unknowns and 4 equations, the solution is not usually determined. Use the least squares solution. This is known as a normal equation and becomes the following equation (8). Here, x, y, and z are solutions of the least square method.

この連立方程式の解は単純であり、以下の（９）式のようになる。

The solution of the simultaneous equations is simple and is as shown in the following equation (9).

この式を計算すれば金マーカーＧのイメージャー座標から金マーカーの治療室座標を得ることができる。そして、癌患部位置は、（１）式より（ｘ＋a、ｙ＋ｂ、ｚ＋ｃ）となる。このように画像処理等によってイメージャー座標から、照射ターゲット座標を求めることができる。

If this equation is calculated, the treatment room coordinates of the gold marker can be obtained from the imager coordinates of the gold marker G. And a cancer affected part position becomes (x + a, y + b, z + c) from (1) Formula. Thus, the irradiation target coordinates can be obtained from the imager coordinates by image processing or the like.

  Now, let the coordinates of the X-ray generation point (target 4) in the X-ray head be (xs, ys, zs). When the polar coordinate system is (r, θ, φ), the following conversion formula is established. However, “r” is an amount called SAD and is a constant value during treatment. “Θ” is not an elevation angle.

アイソセンタとＸ線発生点を結ぶ線がz軸となるような新しい座標系を決める。この新しい座標系を図１８に示す。図１８において、ｘｙｚ座標系の原点Ｃはアイソセンタである。点ｐはｘｙｚ座標系でのＸ線発生点の座標であるが、この点ｐを原点とする新たな座標系から見たターゲット（癌患部）の座標値が、首振りコリメータの照射ターゲット座標となる。そこで、図１８の新たな座標（ｕ、ｖ、ｗ）系から見たターゲット位置を求める。この新しい座標系を得るためには、次式（１１）の座標変換を用いる。

A new coordinate system is determined such that the line connecting the isocenter and the X-ray generation point is the z axis. This new coordinate system is shown in FIG. In FIG. 18, the origin C of the xyz coordinate system is an isocenter. The point p is the coordinate of the X-ray generation point in the xyz coordinate system. The coordinate value of the target (cancer affected part) seen from the new coordinate system with this point p as the origin is the irradiation target coordinate of the swing collimator. Become. Therefore, the target position viewed from the new coordinate (u, v, w) system in FIG. 18 is obtained. In order to obtain this new coordinate system, the coordinate transformation of the following equation (11) is used.

円環行列Ｒｘ（−θ）Ｒｚ（−π／２＋φ）を用いることにより前記の新しい（ｘ、ｙ、ｚ）座標系によるターゲット位置が求まり、さらに回転行列Ｒｙ（π）と並行移動ｒにより図１８に示したＸ線発生点が原点となる座標（ｕ、ｖ、ｗ）系によるターゲット位置が次式によって求まる。

By using the circular matrix Rx (−θ) Rz (−π / 2 + φ), the target position based on the new (x, y, z) coordinate system can be obtained, and further, the rotation matrix Ry (π) and the translation r A target position based on a coordinate (u, v, w) system whose origin is the X-ray generation point shown in FIG.

図１８において、Ｘ線ヘッド１００が出射Ｘ線のビーム軸（ｗ軸）回りに回転角θrollで回転したときは、このｗ軸回りに回転した座標（ｕ'、ｖ'、ｗ'）系で定義されるターゲット位置が（１１）式の座標変換Ｒｚ（ｘ）より求まる。このことより、首振りコリメータの首振り角度（θｕ、θｖ）は、次の（１３）式と（１４）式より求まる。

In FIG. 18, when the X-ray head 100 rotates around the beam axis (w axis) of the outgoing X-ray at the rotation angle θroll, the coordinate (u ′, v ′, w ′) system rotated around the w axis. The defined target position is obtained from the coordinate transformation Rz (x) in the equation (11). From this, the swing angle (θu, θv) of the swing collimator can be obtained from the following equations (13) and (14).

  The rotation angle θroll is determined by the coordinates (x, y, z, yaw, roll, pitch) of the X-ray head 100.

この首振りコリメータの首振り角度（θｕ、θｖ）は、図６、図７におけるｘ軸方向の首振り角とｙ軸方向の首振り角度（θｘ、θｙ）となる。このようにして、セカンダリコリメータ２０の首振り角度（θｘ、θｙ）が求まり、追尾コントローラー７１はこの求めた（θｘ、θｙ）をサブユニットコントローラー８０に渡す。そして、Ｘ線ヘッド内コントローラー９０がこれをサブユニットコントローラー８０から受け取って、セカンダリコリメータ２０は首振り制御を行うので、所望の首振り動作が行われる。
（Ｘ線照射装置）
図８〜図１１はＸ線ヘッド１００を組み込んだＸ線照射装置の構成を示す。図８はＸ線照射装置の正面図、図９は斜視図、図１０は平面図、図１１は図８のＸ−Ｘ断面図である。Ｘ線照射装置は図２、３等を参照して説明したＸ線ヘッド１００をＸ線ヘッドベース３００内に装着している。このＸ線ヘッドベース３００は、大略、内部中空の筒状の形状を成していて、この筒状体の一方（Ｘ線出射側）の先端側にはこの一端を閉塞するように第１のコリメータ（プライマリコリメータ１０）が詰め込まれて装着されている。この第１のコリメータ（プライマリコリメータ１０）の軸心上には、電子銃２（図３参照）から発射される電子線をＸ線に変換するターゲット４が設けられていて、基準となるＸ線軸が第１のコリメータ（プライマリコリメータ１０）の軸心と一致する構成となっている。

The swing angle (θu, θv) of the swing collimator is the swing angle in the x-axis direction and the swing angle (θx, θy) in the y-axis direction in FIGS. In this way, the swing angle (θx, θy) of the secondary collimator 20 is obtained, and the tracking controller 71 passes the obtained (θx, θy) to the subunit controller 80. Then, the X-ray head controller 90 receives this from the subunit controller 80, and the secondary collimator 20 performs swing control, so that a desired swing operation is performed.
(X-ray irradiation equipment)
8 to 11 show the configuration of an X-ray irradiation apparatus in which the X-ray head 100 is incorporated. 8 is a front view of the X-ray irradiation apparatus, FIG. 9 is a perspective view, FIG. 10 is a plan view, and FIG. 11 is a sectional view taken along line XX in FIG. In the X-ray irradiation apparatus, the X-ray head 100 described with reference to FIGS. The X-ray head base 300 has a generally hollow cylindrical shape. The first end of the cylindrical body (the X-ray emission side) is closed so that one end is closed. A collimator (primary collimator 10) is packed and attached. On the axis of the first collimator (primary collimator 10), a target 4 for converting an electron beam emitted from the electron gun 2 (see FIG. 3) into an X-ray is provided. Is configured to coincide with the axis of the first collimator (primary collimator 10).

  Four voice coil motors 150 a, 150 b, 150 c, and 150 d for swinging and controlling the second collimator (secondary collimator 20) in at least two orthogonal directions are respectively provided on the outer peripheral surface of the X-ray head base 300. The circumference is shifted by a quarter of the circumference (the central angle of the corresponding circle is 90 degrees). The voice coil motors 150a to 150d are an example of the swing drive mechanism 25 of FIG. Further, the detection unit 31 (see FIG. 2) of the swing angle detection unit 30A is fixedly connected to the tip of the bracket 180 provided so as to extend from the outer peripheral surface of the X-ray head base 300. A flat reflecting mirror 35 in FIG. 4 is fixed to the outer surface position of the swing base 170 (movable member MV in FIG. 2) facing the detection unit 31.

  The aiming laser unit 5 is provided at the front end portion (X-ray emission side) of the voice coil motor 150a through an appropriate member, and the laser visible light output from the aiming laser unit 5 is constituted by a mirror 7 or the like. The optical system is configured to overlap the X-ray axis. Thus, the X-ray irradiation destination can be confirmed by visually observing the laser visible light. Further, since the ion chamber 27 is fixedly installed by an appropriate member on the outer surface side of the swing base 170 between the mirror 7 and the second collimator (secondary collimator 20), measurement of radiation dose, irradiation direction, and the like. Can be easily performed.

In FIG. 9, arcuate curved motion bearings 151a and 151b are provided between the swing base 170 coupled to the second collimator (secondary collimator 20) and the intermediate member 152. Arc-shaped curved motion bearings 151c and 151d are provided between the intermediate member 152 and the mounting base 153 on the first collimator (primary collimator 10) in a direction orthogonal to the bearing (where 151d is a perspective view of FIG. 9). In this configuration, the swing base 170 can swing smoothly.
(Swing drive mechanism)
Next, the swing drive mechanism will be described with reference to FIGS. 11 to 13 are sectional views taken along line XX in FIG. In FIG. 11 to FIG. 13, the collimators 10 and 20 are not hatched for easy understanding, and the electron gun 2 and the acceleration tube 3 are omitted. FIG. 11 shows a schematic configuration of two voice coil motors 150a and 150d, and all of the voice coil motors 150a to 150d have the same structure. The voice coil motor 150 has a coil support column 155 that has a hollow portion SP inside and extends to the head, and a bobbin 161 is connected to the root thereof. A conductive wire is wound around the bobbin 161 to form a coil. Two annular coil spacers 160 are arranged outside the bobbin 161 at an appropriate interval, and conductive wires (shown by black circles in the figure) are wound between the spacers 160 and outside (right and left sides in the drawing). Three coils 166 are formed. Note that the winding direction of the middle coil and the two outer coils 166 are reversed.

  The magnetic circuit of the voice coil motor 150 is fixed to the outside of the X-ray head base 300. As this magnetic circuit, two cylindrical magnets 165 for generating a magnetic field are provided inside the bobbin 161, and cylindrical inner yokes are formed between the magnets 165 and outside each magnet 165 (the left and right sides in the drawing). A cylindrical outer yoke 157 is formed outside the bobbin 161. Note that the magnetic pole of the magnet 165 exists in the direction of the inner yoke that is in contact, and the magnetic poles facing the two magnets have the same polarity (if one is S, the other is S). As a result, a magnetic flux passes through the gap between the inner yoke and the outer yoke 157, and the coil in this gap is linked to this magnetic flux, and a current flows through the coil to generate a "force". The outer yoke 157 and the inner yoke 156 (a) are coupled to each other by a magnetic base member 158 at the bottom of the voice coil motor. In FIG. 11 to FIG. 13, C1, C2, and C3 indicate gaps in the voice coil motor 150. Furthermore, a swing base 170 having a shape similar to that of an automobile handle in front view is disposed at the tips of the first collimator (primary collimator 10) and the second collimator (secondary collimator 20). The swing base 170 is connected to the coil support column 155, and the central part thereof is connected to the second collimator (secondary collimator 20) via an appropriate member.

  With this configuration, when a current flows in a certain direction (hereinafter also referred to as “positive direction”), the coil support 155 moves in the right direction of the drawing according to Fleming's left hand rule in combination with the magnetic field generated by the magnet 165. When a current flows in a direction opposite to a certain direction (hereinafter also referred to as “reverse direction”), the coil support 155 moves to the left side of the drawing. By passing a current through the voice coil motors 150a and 150d facing each other in the forward direction and the reverse direction, the coil support 155 is moved in the left-right direction of the drawing as indicated by a double-headed arrow. As a result, the swing base 170 moves up and down in the drawing, and the second collimator (secondary collimator 20) swings. The swing base 170 is a bearing (not shown) on the spherical surface of the first collimator (primary collimator 10) (a coupling member provided with an arc-shaped curved motion bearing in two directions so as to be able to operate in two degrees of freedom in FIG. 9). Combined, it can be swung.

  FIG. 12 shows the operation of swinging the second collimator (secondary collimator 20) upward in the drawing. When currents in the reverse direction and the forward direction are supplied to each of the voice coil motor 150a and the voice coil motor 150d, the coil support 155 moves in the left direction (arrow DA direction) and right direction (arrow DB direction), respectively. The swing base 170 moves upward, and as a result, the second collimator (secondary collimator 20) moves upward.

  FIG. 13 shows an operation of swinging the second collimator (secondary collimator 20) downward in the drawing. When currents in the forward direction and the reverse direction are supplied to the voice coil motor 150a and the voice coil motor 150d, the coil support 155 moves in the right direction (arrow DB direction) and the left direction (arrow DA direction), respectively. The swing base 170 moves downward, and as a result, the second collimator (secondary collimator 20) moves downward. As described above, the second collimator (secondary collimator 20) can be swung in the vertical direction of the drawing.

  FIG. 14 is a schematic explanatory diagram for swinging the second collimator (secondary collimator 20) with the four voice coil motors 150a, 150b, 150c, and 150d. As can be seen side by side with FIG. 8, the states of FIGS. 12 and 13 correspond to the states of FIGS. 14 (a) and 14 (b). As shown in FIG. 14A, the force for moving the swing base 170 by the voice coil motors 150a and 150d becomes VDA (shown in the form of “vector” in the figure), and the force for moving the swing base 170 by the voice coil motors 150b and 150c. If VDB is VDB, the resultant force is V1 and an upward force is applied. On the other hand, if the power supplied to the four motors is reversed, the force that moves the swing base 170 by the voice coil motors 150a and 150d is VDD, and the force that moves the swing base 170 by the voice coil motors 150b and 150c is VDC. V2 becomes downward force. As a result, as shown in FIGS. 14A and 14B, when the motor is driven, the second collimator (secondary collimator 20) can swing up and down. This swing amount adjustment is performed by adjusting the supply current to each motor.

FIG. 14C shows a state in which the supply current direction of the voice coil motors 150a and 150d is reversed in the state shown in FIG. As shown in FIG. 14 (c), if the force that moves the swing base 170 by the voice coil motors 150b and 150c is VDF, and the force that moves the swing base 170 by the voice coil motors 150a and 150d is VDE, the resultant force is V3. Power works. On the other hand, FIG. 14D shows a state in which the direction of supply current of the voice coil motors 150b and 150c is reversed in the state shown in FIG. As shown in FIG. 14D, when the force to move the swing base 170 by the voice coil motors 150a and 150d is VDG, and when the force to move the swing base 170 by the voice coil motors 150b and 150c is VDH, the resultant force is V4 and the leftward direction. Power works. As a result, when the motor is driven as shown in FIGS. 14C and 14D, the second collimator (secondary collimator 20) can swing in the left-right direction. This swing amount adjustment is performed by adjusting the supply current to each motor. The motor control as described above is configured to be performed by the controller 90 in the X-ray head that has received the swing angle setting information (θx, θy). As another form of the voice coil motor, one coil and one magnet may be configured. In this case, the base member 158 that joins the outer yoke 157 and the inner yoke 156 (a) in FIG. 11 is also formed of a yoke material, and a gap between the inner yoke 156 (c) on the voice coil motor open end side and the outer yoke 157 is formed. In this configuration, one coil on the bobbin is formed at a position interlinking with the magnetic path passing through (in FIG. 11, the inner yoke 156 (b) does not exist). Since the voice coil motor is allowed to tilt the movable part (see FIGS. 12 and 13), if configured as in the present embodiment, the link mechanism is not required, and the vibration problem can be avoided and driven stably. be able to. Therefore, when a linear motor such as a piezo actuator is employed as the swing drive mechanism, it may be combined with a highly accurate link mechanism.
(Dimensions, equipment appearance, etc.)
As described above, by adjusting the direction and magnitude of the current of each of the voice coil motors 150a to 150d, the second collimator (secondary collimator 20) can be swung 360 degrees in all directions by “3 (deg)”. Further, the size of the X-ray irradiation apparatus shown in FIGS. 8, 9, and 10 is a maximum of 250 (mm) in the vertical direction, a maximum of 250 (mm) in the horizontal direction, a maximum of 200 (mm) in the depth direction, and a weight of about 6 (kg). And at the present stage, miniaturization has been achieved.

FIG. 15 is an external view of the radiation therapy system 1. In this figure, the set of the X-ray tube 50a and the FDP 60a and the set of the X-ray tube 50b and the FDP 60b are omitted, but the arrangement configuration of the X-ray tubes 50a and 50b and the FDP 60a and 60b and the function as an imager are as follows. This is as described in the item “Image processing” with reference to FIGS. 16 and 17. Patient P is placed on couch 190 and undergoes X-ray therapy. At that time, the six-axis manipulator 200 moves the X-ray head 100 to a required position. These controls are performed by a control device. As shown in FIG. 15, the apparatus including the X-ray head 100 whose external appearance has been described with reference to FIGS. 8 to 10 has a size and weight that can be mounted on the arm of the six-axis manipulator 200. A configuration in which the center of rotation of the swing motion of the swing unit composed of the second collimator (secondary collimator 20) and the components attached thereto (such as the swing angle detection unit 30) is substantially coincident with the center of gravity of the swing unit. Then, it is preferable for the reason that the swing portion does not swing freely.
(Modification 1)
19 to 22 show a swing angle detector 30B as another configuration example of the displacement amount detection means. Instead of the swing angle detector 30A using the optical system of FIG. 4, an encoder-type swing angle detector 30B may be used. FIG. 19 is a front view of the linear encoder 303 which is a part of the swing angle detector 30B, and FIG. 20 is a perspective view showing the positional relationship between the voice coil motors 150a to 150d and the linear encoder 303. As shown in FIG. 20, the swing angle detector 30 </ b> B includes at least one set of linear encoders 303 disposed along each of the X axis and the Y axis that are the swing directions of the secondary collimator 20. In the example of FIG. 20, the swing angle detector 30B has four linear encoders 303a to 303d (generally referred to as “linear encoder 303” as appropriate), and the linear encoders 303b and 303d are linear encoders along the X axis. 303a and 303c are arranged along the Y axis. The linear encoders 303a and 303b form one set, and the linear encoders 303c and 303d form another set. By using either one of the sets, the displacement amount (swing angle) of the secondary collimator 20 from the reference position in the X direction and the Y direction can be detected. However, using two sets improves the reliability of the apparatus.

  Returning to FIG. 19, each linear encoder 303 includes a linear scale 301 and an encoder sensor 302. The linear scale 301 is a circular arc having a radius R centered on a position S when the position of the target 4 which is the swinging origin, that is, the X-ray generation source is translated to the arrangement surface of the linear encoder 303 in parallel with the X axis or the Y axis. Having a scaler surface. The encoder sensor 302 has a sensor surface at a position facing the arc-shaped scaler surface of the linear scale 301. As the second collimator 20 swings by the voice coil motors 150 a to 150 d, the encoder sensor 302 performs an arc motion while maintaining a certain distance from the linear scale 301 and is displaced relative to the linear scale 301.

  FIG. 21 is an enlarged view of the linear encoder 303. Scales at regular intervals are formed on the arc-shaped scaler surface 301 f of the linear scale 301. The scale interval, that is, the unit distance correlates with the resolution of the linear scale 301. The position information of the scaler surface 301f read by the encoder sensor 302 represents angle information determined by the resolution and the radius of curvature R.

  As the type of the linear encoder 303, a magnetic or optical encoder can be used. In the case of the magnetic type, for example, S-pole and N-pole micro magnets are alternately arranged on the scaler surface 301f, and the relative displacement is detected by the magnetic sensor of the encoder sensor 302. In the case of the optical type, for example, the reflective surface and the absorbing surface are alternately arranged on the scaler surface 301f, and the relative displacement is detected by the optical sensor of the encoder sensor 302. The magnetic encoder is excellent in environmental robustness against dust, oil, and the like. If the environment is good, a low-cost optical reflective encoder can be used.

  FIG. 22 is a diagram for explaining the detection of the swing angle based on the information read by the encoder sensor 302. The unit distance Δd of the linear scale 301 can be converted into a unit angle using the radius of curvature R of the scaler surface 301f. Δd = R × sin θ, and when θ is small, it can be approximated as sin θ≈Δθ. The required resolution is appropriately determined from the order of nanometers (nm) to several hundred microns according to the size of the affected area, the spot diameter of the irradiated X-rays, and the like. By converting the position information read by the encoder sensor 302 into an angle, the swing angle θ is obtained.

  The outputs of the linear encoders 303b and 303d arranged along the X axis represent the swing angle θy around the Y axis. The outputs of the linear encoders 303a and 303c arranged along the Y axis are obtained by using two sets of linear encoders for detecting the swing angle (θx, θy) representing the swing angle θx around the X axis. It is possible to detect an abnormality of the sensor itself, and to back up when the sensor fails. The swing angle (θx, θy) detected by the swing angle detector 30B using the linear encoder 303 corresponds to (θ′x, θ′y) used for feedback control in FIG.

  The two types of linear encoders may use the same type of linear encoder 303, one set may be a magnetic linear encoder, and the other set may be an optical linear encoder. A set of linear encoders 303 may be used in combination with the swing angle detector 30A of FIG.

  As an output type of the linear encoder 303, there are an incremental type and an absolute type. In the incremental type, it is necessary to determine the origin every time the power is turned off and on. Absolute type is not necessary because position information is recorded. Either output type can be used.

  As for the positional relationship between the voice coil motors 150a to 150d and the linear encoders 303a to 303d, the linear encoder 303 is inclined by 45 degrees with respect to the diagonal line connecting the opposing voice coil motors 150 as shown in FIG. Good. In this case, the X axis and Y axis, which are the reference for the swinging direction, are inclined 45 degrees with respect to the diagonal lines of the voice coil motors 150a to 150d, and the linear encoders 303a to 303d are installed in parallel to the X axis or the Y axis. . This arrangement is advantageous for downsizing the apparatus.

A configuration in which the linear encoders 303a to 303d are arranged in parallel to the diagonal lines of the voice coil motors 150a to 150d is also possible. In this case, the movable axes of the voice coil motors 150a to 150d coincide with the X and Y axes that are the reference for the swinging direction, and the position-angle conversion by the linear encoder 303 is simplified, so that more accurate control is possible. I can expect.
(Modification 2)
23 and 24 show a collimator device 101B using a third collimator 310 as a modification of the collimator. The point that the second collimator (secondary collimator) 20 </ b> A is arranged so as to be able to swing is provided with a gap OP inside the first collimator (primary collimator) 10, as in FIG. 2. In FIG. 23, the third collimator 310 is exchangeably inserted into the second collimator 20A so that the irradiation field can be changed. Depending on the position and size of the affected area, it may be desirable that the diameter of the irradiated X-ray beam is narrowed down. It is desirable that the beam diameter can be appropriately selected and changed according to the position and size of the affected area. The third collimator 310 realizes such irradiation field adjustment.

  The second collimator 20 </ b> A has a shape different from that of the secondary collimator 20 of FIG. 2, assuming insertion of the third collimator 310. A function common to the second collimators 20 and 20 </ b> A is a function of swinging using a gap OP between the inner wall of the first collimator 10. The second collimator 20A is integrated with the third collimator, has a function of passing X-rays in the axial direction, a function of forming an irradiation field, and an outer shape of the second collimator 20A and a shape of the first collimator 10. And fulfills the function of reducing the leakage dose. The function of irradiation field formation is realized mainly by the third collimator.

The second collimator 20 </ b> A has a shape that can receive the third collimator 310 and can swing within the first collimator 10. As an example, the outer wall of the second collimator 210 draws a gentle curve to achieve smooth peristalsis in the gap OP and a stable X-ray shielding effect. FIG. 24 shows an example of insertion of the third collimator 310. FIG. The outer shape of the third collimator 310A in FIG. 24A and the third collimator 310B in FIG. 24B are the same, but the diameter of the collimating space 3001 is different. The diameter of the collimating space 3001 in FIG. 24A is smaller than the diameter of the collimating space 3001 in FIG. 24B, and the X-ray irradiation beam can be further narrowed down. A desired beam diameter can be obtained by inserting the third collimator 310A or 310B into the second collimator 20A in a replaceable manner.

  The third collimators 310A and 310B are inserted up to the output end 2002 of the second collimator 20A and swing together with the second collimator 20A. The swing motion itself within the first collimator 10 is performed by the second collimator 20A. The third collimator 310 is fitted in the space inside the second collimator 20A, and as a result, swings together with the second collimator 20A. With this configuration, the irradiation field can be easily changed without disturbing the swing motion of the second collimator 20A.

In the case where the third collimator is not used, a configuration is also possible in which a plurality of second collimators having different irradiation fields are prepared so that the second collimator can be replaced.
(Control system hardware configuration and processing flow)
FIG. 25 is a hardware configuration diagram of the control system. The control device 120 includes a processor 1201, a memory 1202, and an input / output interface 1203, which are connected to each other via a bus 1205. The X-ray head controller 90 includes a processor 901, a memory 902, and an input / output interface 903, which are connected to each other via a bus 905. In FIG. 25, the control device 120 and the X-ray head controller 90 are depicted as separate hardware, but a single hardware is formed by arranging a SoC (System on Chip) and a memory chip on one control board. It may be realized with.

  The processor 1201 of the control device 120 controls the overall operation of the control device 120 and performs various calculations. The memory 1202 includes a read only memory (ROM) that stores a basic input / output program and an arithmetic program, and a random access memory (RAM) that is used as a work area for the processor 1201. The input / output interface 1203 includes a connection interface with an external device, and may include a communication device that operates according to a predetermined protocol as necessary. The input / output interface 1203 receives the robot coordinates, that is, the coordinates of the current X-ray head (x, y, z, yaw, roll, pitch) from the 6-axis manipulator 200 and stores them in the memory 1202. Further, the coordinates of the irradiation marker (affected area) calculated based on the coordinates of the gold marker or the gold marker coordinates are received from the imager 65 (see FIG. 7) and stored in the memory 1202. The processor 1201 reads the coordinate information from the memory 1202, calculates the swing angle of the second collimator 20 (or 20A), and supplies the swing angle instruction to the in-head controller 90 via the input / output interface 1203.

  The processor 901 of the X-ray head controller 90 controls the overall operation of the X-ray head controller 90 and performs various calculations. The memory 902 includes a ROM (read only memory) that stores basic input / output programs and arithmetic programs, and a RAM (random access memory) that is used as a work area of the processor 1201. The input / output interface 903 includes a connection interface with an external device, and may include a communication device that operates according to a predetermined protocol as necessary. The input / output interface 903 receives the swing angle instruction from the control device 120 and stores it in the memory 902. The input / output interface 903 receives the detected value of the current swing angle of the second collimator 20 (or 20A) from the swing angle detector 30A or 30B and stores it in the memory 902. The processor 901 reads the swing angle instruction and the detected value of the swing angle from the memory 902, calculates the swing drive amount, and outputs a swing drive signal from the input / output interface 903.

  When the control device 120 and the X-ray head controller 90 are realized by a single control board, the control board is arranged in the main body of the 6-axis manipulator 200, and the robot position coordinates (X-ray head position coordinates) are obtained directly. May be. Further, the control board and the swing drive mechanism 25 or the swing angle detector 30A (or 30B) may be connected by a signal line to input / output drive current and sensor output.

  FIG. 26 shows a basic processing flow of the radiation therapy system 1. First, the robot coordinates (x, y, z, yaw, roll, pitch) of the 6-axis manipulator 200 and the coordinates (x, y, z) of the gold marker are acquired (S11). Instead of the coordinates of the gold marker, the coordinates (x, y, z) of the affected part calculated by the imager 65 may be acquired. In the latter case, it is not necessary for the control device 120 to calculate the affected part coordinates.

  Next, based on the acquired coordinate information, the swing angle (θx, θy) of the second collimator 20 (or 20A) is calculated, and this is given to the X-ray head 100 as an angle command (S12). The calculation of the swing angle is as described with reference to FIG.

  Based on the given swing angle and feedback information of the detected swing angle, the swing drive mechanism 25 is controlled to drive the second collimator inside the first collimator (S13). S11 to S13 are repeated until there is an irradiation end command (S14).

  The processing in FIG. 26 may be performed by the processor 1201 and / or 901 executing a program recorded in the memory 1202 and / or the memory 902. When a single control board is used, a microprocessor on the control board may execute a program recorded in a storage medium such as a ROM.

  FIG. 27 is a slow chart showing a specific example of the process of step S13 of FIG. For example, the X-ray head controller 90 reads the control target angle (θx, θy) from the memory 902 (S21). The control target angles (θx, θy) may be given from the control device 120 and stored in the memory 902, or the control device 120 and the X-ray head controller 90 may be formed by a single control board. May be calculated by a processor on the control board and stored in a memory on the board.

  The X-ray head controller 90 acquires the sensor value from the swing angle detector 30A or 30B (S22), and calculates the current swing angle (θ′x, θ′y) (S23). Step S21 and steps S22 and S23 are out of order and may be performed simultaneously. The current swing angle (θ′x, θ′y) may be calculated by the swing angle detector 30A or 30B and input to the controller 90 in the X-ray head.

  The X-ray head controller 90 compares the target value of the swing angle with the current value, calculates the current values (Ix, Iy) of the voice coil motors 150a to 150d (S24), and determines the determined current values (Ix, Iy). ) As a coil current (S25). Each of the voice coil motors 150a to 150d drives the second collimator by a given coil current. Give this. S21 to S25 are repeated until radiation irradiation is completed (S26).

  The processing of FIG. 27 may be performed according to a program recorded in the memory 902 of the controller 90 in the X-ray head. With the method of FIGS. 26 and 27, accurate radiation irradiation following body movement is realized.

  As described above, according to the embodiment of the present invention, the second collimator (secondary collimator 20 or 20A) is arranged with a gap (OP) in the first collimator (primary collimator 10). Is done. In the first collimator (primary collimator 10), using the gap (OP), only the second collimator (secondary collimator 20) is swung, and the object is scanned for radiation irradiation. The operation can be performed at high speed. As a result, X-ray irradiation can be continuously performed following the movement of the affected part, and faithful tracking of the moving object becomes possible. For example, it is also possible to perform X-ray irradiation on an affected area having a complicated two-dimensional shape by gradually increasing or decreasing the swing angle for each swing of one or more times.

  Further, in the present invention, various modifications can be made in the configuration of the hardware and software, and it goes without saying that this modification is also included in the present invention as long as the gist of the present invention is satisfied. Yes.

  INDUSTRIAL APPLICABILITY The present invention can be widely used for radiation therapy for a patient having an affected part with a complicated shape, a non-destructive inspection apparatus for a structure, and the like.

DESCRIPTION OF SYMBOLS 1 Radiation therapy system 2 Electron gun 3 Acceleration tube 4 Target 5 Aiming laser unit 6 Mirror 7 Mirror 10 Primary collimator (first collimator)
20, 20A Secondary collimator (second collimator)
25 Swing drive mechanism 27 Ion chambers 30, 30A, 30B Swing angle detectors 50a, 50b X-ray tubes 60a, 60b FPD (flat panel detector)
90 Controller in X-ray head 100 X-ray head 101A, 101B Collimator device 120 Control device 150, 150a to 150d Voice coil motor 200 6-axis manipulator 210 Arm 301 Linear scale 302 Encoder sensor 303 Linear encoder 310 Third collimator

JP-A-5-253309 (page 2-3, FIG. 2) Japanese Patent Laid-Open No. 5-337207 (page 3-4, FIG. 3) JP-A-2004-65808 (pages 15-16, FIG. 14) JP 2007-267971 A (Pages 9-12, FIG. 7) JP 2003-175117 A (pages 5-6, 10-11)

Claims (16)

A first collimator that internally arranges a target for converting an electron beam generated from an electron beam source into radiation, and suppresses leakage of the radiation to the outside;
A second collimator disposed in the first collimator with a gap and passing the radiation in the axial direction of the first collimator,
A collimator device characterized in that the second collimator is moved in the first collimator. The collimator device according to claim 1,
A third collimator that is replaceably disposed within the second collimator;
A collimator device further comprising: The collimator device according to claim 2,
The third collimator is fitted in an internal space of the second collimator and swings integrally with the second collimator. In the collimator device according to any one of claims 1 to 3,
A collimator device comprising: a drive mechanism for swinging the second collimator in two directions; and drive mechanism control means for controlling the drive mechanism. The collimator device according to claim 4,
The drive mechanism control means controls the drive mechanism so that the target exists on the axis of the second collimator. The collimator device according to claim 4,
A displacement amount detecting means for detecting a displacement amount from a reference position of the second collimator;
The collimator apparatus, wherein the drive mechanism control means controls the drive mechanism based on a displacement amount detected by the displacement amount detection means. The collimator device according to claim 6,
The displacement detection means includes: a first encoder arranged along a first direction of the two directions; and a second encoder arranged along a second direction orthogonal to the first direction. A collimator device having at least one set. In the collimator device according to any one of claims 1 to 7,
A collimator device comprising an optical system for guiding the optical axis of a visible light laser provided on a member coupled to the second collimator to the outside of the device so as to coincide with the axis of the second collimator . In the collimator device according to any one of claims 4 to 7,
The drive mechanism includes a voice coil motor. In the collimator device according to any one of claims 1 to 7,
1. A collimator apparatus comprising a dosimeter for measuring a radiation dose and an irradiation direction on a radiation emission side. In the collimator device according to any one of claims 1 to 7,
A collimator device characterized in that the rotation center of the swing of a swing part formed by the second collimator and parts attached to the second collimator is substantially coincident with the center of gravity of the swing part. A collimator device according to any one of claims 1 to 11,
At least two pairs formed by an X-ray tube that generates X-rays and an X-ray detector that detects the X-rays in a plane;
Based on the detection signal of the X-ray detector, an arithmetic processing means for obtaining a motion in the vicinity of the affected part in which a marker for attenuating X-rays is embedded in advance;
A radiation therapy system comprising: The radiotherapy system according to claim 12,
The radiotherapy system characterized by controlling the peristalsis of the second collimator based on information obtained by the arithmetic processing means and indicating movement in the vicinity of the affected area where the marker is embedded. An electron beam source that generates an electron beam; a target that converts the electron beam into radiation; a first collimator that places the target inside to suppress leakage of the radiation to the outside; and the first collimator A second collimator that is arranged in the collimator with a gap and allows the radiation to pass in the direction of its own axis, a drive mechanism that swings the second collimator in the first collimator, and this drive An X-ray head having drive mechanism control means for controlling the mechanism;
a manipulator equipped with an n-axis (n is 6 or more) movable arm;
With
The radiotherapy system, wherein the X-ray head is connected to a tip of the arm. A method for controlling a collimator comprising:
A target that converts an electron beam generated from an electron gun into radiation is disposed inside, and a gap is formed between the first collimator and the first collimator that suppresses leakage of the radiation to the outside. A second collimator that allows the radiation to pass in the direction of its own axis,
Swinging the second collimator in the first collimator toward the target irradiation position of the radiation;
A control method characterized by that. A first collimator that suppresses leakage of the radiation to the outside by arranging a target that converts an electron beam generated from an electron gun into radiation, and a gap in the first collimator. A second collimator arranged to pass the radiation in its axial direction and a drive mechanism for swinging the second collimator in the first collimator;
A procedure for obtaining a target irradiation position of the radiation;
Driving the second collimator toward the target irradiation position;
The control program characterized by realizing.

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