JP2009109207A - X-ray generation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray generation device capable of radiating a radiation having a larger dose. <P>SOLUTION: The device includes an acceleration device for accelerating charged particles, and a target 52 for radiating a radiation by being irradiated with the charged particles. In this case, the target 52 is not flat but includes a curved surface, and includes a part wherein the edge 73 is arranged on a plane 72. Such a target 52 includes a large area of a portion irradiated with the charged particles, and can reduce heat generation per unit area of the portion, in comparison with a flat target. In this case, the device can increase the dose of the charged particles with which the target is irradiated, and can increase the dose of a radiation to be radiated. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an X-ray generator, and more particularly to an X-ray generator that generates radiation by bremsstrahlung.

  Radiotherapy is known in which a patient is treated by irradiating the affected part (tumor) with therapeutic radiation. The radiotherapy is desired to have a high therapeutic effect, and the therapeutic radiation is desired to have a smaller dose applied to normal cells than the dose applied to the affected cells. . The patient has a maintenance time during which the therapeutic radiation is applied (eg, about 30 seconds) to reduce the risk of over-irradiation of the normal site if the affected location may move during treatment due to breathing You may need to hold your breath inside. In order to further reduce the burden on the patient, it is desired to further reduce the time required for radiotherapy, and a radiotherapy apparatus in which the dose rate of the therapeutic radiation applied to the affected area is larger is desired.

  As the therapeutic radiation, radiation generated by bremsstrahlung is widely applied. An X-ray irradiation head that generates such therapeutic radiation includes an acceleration tube that generates a high-energy electron beam and an X-ray target that is irradiated with the electron beam. As the X-ray target, a plate made of a high atomic number material exemplified by tungsten, gold, tantalum and the like is exemplified. The therapeutic radiation can increase the dose rate by increasing the current of the electron beam applied to the X-ray target. When the target is irradiated with a high-current electron beam, the heat generation becomes significant and it may be difficult to cool the target. For this reason, the dose rate of therapeutic radiation that such an X-ray irradiation head can irradiate the affected area cools the X-ray target irradiated with the electric power for accelerating the electron beam and the charged particles. The upper limit (for example, about 500 to 1000 cGr / min) is determined by the capacity.

  In order to further reduce the burden on the patient, the radiotherapy apparatus is desired to further reduce the time required for radiotherapy, and it is desired that the dose rate of the therapeutic radiation irradiated to the affected area is larger. The therapeutic radiation is desired to have a high dose rate, and is desired to be concentrated in a narrow range.

  In Japanese Patent No. 3803845, the size of the X-ray irradiation field in the incident direction of the electron beam can be adjusted, and the side of the apparatus is the irradiation position, so that the electron beam is a vertical beam. An irradiation-use X-ray generator using an electron beam accelerator that can reduce the distance between the target and the floor and reduce the construction cost of the irradiation chamber is disclosed. The X-ray generator using irradiation by the electron beam accelerator is provided with an incident window for the electron beam from the electron beam accelerator at the top of the X-ray generation container, and a plurality of rectangular shapes on the left and right sides of the electron beam incident path in the container. The X-ray generating metal plates are arranged in two rows of target plates arranged at intervals in the up and down direction, showing a reverse octagonal shape, and the bottom target plate is a saddle-shaped one bent at the center. The X-rays are extracted in a direction transverse to the incident direction of the electron beam by tilting each target plate at an appropriate angle with respect to the incident direction of the electron beam.

  Japanese Patent Laid-Open No. 04-367669 discloses a radiotherapy apparatus that enables effective use of the radiation X-ray dose of an X-ray target, and at the same time, makes the absorbed dose of a local affected area larger than that of the surrounding area. It is disclosed. The radiotherapy apparatus includes a collimator including a charged particle generator, an X-ray target that generates X-rays by collision of the charged particles, and a collimator having a spot hole that narrows the X-rays onto the spot. The X-ray target is installed at the entrance of the spot hole.

Japanese Patent No. 3803845 Japanese Patent Laid-Open No. 04-367669

An object of the present invention is to provide an X-ray generator that emits a larger dose of radiation.
Another object of the present invention is to provide an X-ray generator that further reduces heat generation of a target.
Still another object of the present invention is to provide an X-ray generator that irradiates a target with a larger dose of charged particles.
Still another object of the present invention is to provide a radiotherapy apparatus that further reduces the burden on a patient who is subjected to radiotherapy.
Still another object of the present invention is to provide a radiotherapy apparatus that further increases the dose rate of therapeutic radiation applied to a subject.

  In the following, means for solving the problems will be described using the reference numerals used in the best modes and embodiments for carrying out the invention in parentheses. This reference numeral is added to clarify the correspondence between the description of the claims and the description of the best mode for carrying out the invention / example, and is described in the claims. It should not be used to interpret the technical scope of the invention.

  The X-ray generator (16) according to the present invention includes an acceleration device (51) that accelerates charged particles (57), and a target (52) that emits radiation (59) when the charged particles (57) are irradiated. 81) (83) (85) (87) (91). At this time, the targets (52) (81) (83) (85) (87) (91) are not flat but curved, and the edges (73) (82) (84) (86) (88) The part arrange | positioned on a plane (72) is included. Such targets (52), (81), (83), (85), (87), and (91) have a larger area of the portion irradiated with the charged particles (57) than that of the flat target. The heat generation per unit area can be reduced. At this time, the X-ray generator (16) can increase the dose of the charged particles (57) irradiated to the targets (52) (81) (83) (85) (87) (91) and emits them. The dose of radiation (59) can be increased.

  That portion is convex toward the acceleration device (51). At this time, the dose distribution of the radiation (59) can be concentrated in the center.

  The part is formed in a rotating object with respect to an axis (71) parallel to the direction in which the charged particles (57) are irradiated, for example, formed along a conical conical surface, formed along a spherical surface, It is preferably formed along the spheroid. Alternatively, the portion is preferably formed along the pyramid surface of the pyramid.

  The X-ray generator (16) according to the present invention further includes cooling devices (74) (94, 95) for cooling the targets (52) (81) (83) (85) (87) (91). Such a cooling device (74) (94, 95) reduces the heat generation of the targets (52) (81) (83) (85) (87) (91) due to irradiation with the charged particles (57). . That is, such a target (52) (81) (83) (85) (87) (91) is an X-ray generator (16) in which such a cooling device (74) (94, 95) is joined. It can also be applied to.

  The X-ray generator (16) according to the present invention has another target (93) that emits radiation (59) when irradiated with charged particles (57) that have passed through the target (92) of the charged particles (57). ). That is, the X-ray generator (16) according to the present invention includes a plurality of targets (92, 93) that emit radiation (59) when irradiated with charged particles (57). At this time, the X-ray generator (16) according to the present invention can reduce heat generation per unit area of the portion irradiated to the charged particles (57) in the target (91), and the target (91) The dose of charged particles (57) to be irradiated can be increased, and the dose of radiation (59) to be emitted can be increased.

  The radiotherapy apparatus (3) according to the present invention supports the X-ray generator (16) according to the present invention and the X-ray generator (16) so that the radiation (59) is irradiated to a part of the subject (43). It is preferable to provide a supporting device (11, 12, 14, 15).

  The X-ray generator manufacturing method according to the present invention is the target (52) (81) (81) when the target (52) (81) (83) (85) (87) (91) is irradiated with charged particles (57). 83) (85) (87) (91) a step (S2) of acquiring a dose distribution of the radiation (59) emitted from the target, and the targets (52) (81) (83) (85) based on the dose distribution. (87) It is preferable to include a step (S1) of changing the design of the shape of (91). Alternatively, the X-ray generation device manufacturing method according to the present invention is the target (52) (81) when the charged particles (57) are irradiated to the targets (52) (81) (83) (85) (87) (91). ) (83) (85) (87) (91) The step (S2) of obtaining the calorific value or temperature distribution of the target and the targets (52) (81) (83) (85) based on the calorific value or temperature distribution (87) It is preferable to include a step (S1) of changing the design of the shape of (91).

  The X-ray generator according to the present invention can reduce the heat generation per unit area of the portion irradiated with the charged particles as compared with the case where the target is flat. As a result, the X-ray generator according to the present invention can increase the dose of charged particles irradiated to the target, can increase the dose of radiation to be emitted, and is suitable for use in radiotherapy. is there.

  An embodiment of a radiation therapy system according to the present invention will be described with reference to the drawings. The radiotherapy system 1 includes a radiotherapy apparatus control apparatus 2 and a radiotherapy apparatus 3 as shown in FIG. The radiation therapy apparatus control apparatus 2 is a computer exemplified by a personal computer. The radiotherapy apparatus control apparatus 2 is connected to the radiotherapy apparatus 3 so that information can be transmitted bidirectionally.

  FIG. 2 shows the radiation therapy apparatus 3. The radiotherapy apparatus 3 includes a turning drive device 11, an O-ring 12, a traveling gantry 14, a swing mechanism 15, and an X-ray generator 16. The swivel drive device 11 supports an O-ring 12 on a base so as to be rotatable about a rotation shaft 17, and is controlled by the radiotherapy device control device 2 to rotate the O-ring 12 around the rotation shaft 17, thereby The turning angle of the ring 12 is output. The rotating shaft 17 is parallel to the vertical direction. The O-ring 12 is formed in a ring shape with the rotation shaft 18 as a center, and supports the traveling gantry 14 so as to be rotatable about the rotation shaft 18. The rotating shaft 18 is perpendicular to the vertical direction and passes through an isocenter 19 included in the rotating shaft 17. The rotating shaft 18 is further fixed to the O-ring 12, that is, rotates around the rotating shaft 17 together with the O-ring 12. The traveling gantry 14 is formed in a ring shape centered on the rotation shaft 18, and is disposed so as to be concentric with the ring of the O-ring 12. The radiation therapy apparatus 3 further includes a travel drive device (not shown). The travel drive device is controlled by the radiotherapy device control device 2 to rotate the travel gantry 14 around the rotation shaft 18 and outputs the travel angle of the travel gantry 14 with respect to the O-ring 12.

  The swing mechanism 15 is fixed inside the ring of the traveling gantry 14 and supports the X-ray generating device 16 on the traveling gantry 14 so that the X-ray generating device 16 is disposed inside the traveling gantry 14. The head swing mechanism 15 has a pan axis 21 and a tilt axis 22. The pan shaft 21 is fixed to the traveling gantry 14 and is parallel to the rotation shaft 18 without intersecting with the rotation shaft 18. The tilt axis 22 is orthogonal to the pan axis 21. The head swing mechanism 15 is controlled by the radiotherapy device controller 2 to rotate the X-ray generator 16 around the pan axis 21 and rotate the X-ray generator 16 around the tilt axis 22.

  The X-ray generator 16 is controlled by the radiotherapy apparatus controller 2 and emits therapeutic radiation 23. The therapeutic radiation 23 is radiated substantially along a straight line passing through an intersection where the pan axis 21 and the tilt axis 22 intersect. The therapeutic radiation 23 is formed to have a uniform intensity distribution. The therapeutic radiation 23 is further partially shielded, and the shape of the irradiation field when the therapeutic radiation 23 is irradiated to the patient is controlled.

  When the X-ray generator 16 is supported by the traveling gantry 14 in this manner and the X-ray generator 16 is once adjusted to the isocenter 19 by the swing mechanism 15, the therapeutic radiation 23 is driven to rotate. Even if the O-ring 12 is rotated by the apparatus 11 or the traveling gantry 14 is rotated by the traveling drive apparatus, the O-ring 12 always passes through the isocenter 19 at all times. In other words, the therapeutic radiation 23 can be irradiated from any direction toward the isocenter 19 by running and turning.

  The radiotherapy apparatus 3 further includes a plurality of imager systems. That is, the radiotherapy apparatus 3 includes diagnostic X-ray sources 24 and 25 and sensor arrays 32 and 33. The diagnostic X-ray source 24 is supported by the traveling gantry 14. The diagnostic X-ray source 24 is disposed inside the ring of the traveling gantry 14 and has an angle formed by a line segment connecting the diagnostic X-ray source 24 from the isocenter 19 and a line segment connecting the X-ray generator 16 from the isocenter 19. It is arranged at a position that makes an acute angle. The diagnostic X-ray source 24 is controlled by the radiotherapy apparatus controller 2 and emits diagnostic X-rays 35 toward the isocenter 19. The diagnostic X-ray 35 is a conical cone beam which is emitted from one point of the diagnostic X-ray source 24 and has the one point as a vertex. The diagnostic X-ray source 25 is supported by the traveling gantry 14. The diagnostic X-ray source 25 is disposed inside the ring of the traveling gantry 14 and has an angle formed by a line segment connecting the diagnostic X-ray source 25 from the isocenter 19 and a line segment connecting the X-ray generator 16 from the isocenter 19. It is arranged at a position that makes an acute angle. The diagnostic X-ray source 25 is controlled by the radiotherapy apparatus controller 2 and emits diagnostic X-rays 36 toward the isocenter 19. The diagnostic X-ray 36 is a cone-shaped cone beam emitted from one point of the diagnostic X-ray source 25 and having the one point as a vertex.

  The sensor array 32 is supported by the traveling gantry 14. The sensor array 32 receives the diagnostic X-ray 35 emitted from the diagnostic X-ray source 24 and transmitted through the subject around the isocenter 19 and generates a transmission image of the subject. The sensor array 33 is supported by the traveling gantry 14. The sensor array 33 receives the diagnostic X-ray 36 emitted from the diagnostic X-ray source 25 and transmitted through the subject around the isocenter 19 and generates a transmission image of the subject. Examples of the sensor arrays 32 and 33 include FPD (Flat Panel Detector) and X-ray II (Image Intensifier).

  According to such an imager system, a transmission image centered on the isocenter 19 can be generated based on the image signals obtained by the sensor arrays 32 and 33.

  The radiation therapy apparatus 3 further includes a sensor array 31. The sensor array 31 is arranged so that a line segment connecting the sensor array 31 and the X-ray generator 16 passes through the isocenter 19 and is fixed inside the ring of the traveling gantry 14. The sensor array 31 receives the therapeutic radiation 23 emitted from the X-ray generator 16 and transmitted through the subject around the isocenter 19, and generates a transmission image of the subject. Examples of the sensor array 31 include FPD (Flat Panel Detector) and X-ray II (Image Intensifier).

  The radiation therapy apparatus 3 further includes a couch 41 and a couch driving device 42. The couch 41 is used when a patient 43 to be treated by the radiation therapy system 1 lies down. The couch 41 includes a fixture not shown. The fixture secures the patient to the couch 41 so that the patient does not move. The couch driving device 42 supports the couch 41 on the base and moves the couch 41 under the control of the radiation therapy device control device 2.

  FIG. 3 shows the X-ray generator 16. The X-ray generator 16 includes an electron beam accelerator 51, an X-ray target 52, a primary collimator 53, a flattening filter 54, a dosimeter 61, a secondary collimator 55, and a multileaf collimator 56. The electron beam accelerator 51 irradiates the X-ray target 52 with an electron beam 57 generated by accelerating electrons. The X-ray target 52 is formed from a high atomic number material. Examples of the high atomic number substance include tungsten, a tungsten alloy, gold, and tantalum. The X-ray target 52 emits radiation 59 generated by bremsstrahlung when the electron beam 57 is irradiated. The radiation 59 is radiated substantially along a straight line passing through a virtual point source 58, which is a point inside the X-ray target 52. The primary collimator 53 is made of a high atomic number substance (for example, lead, tungsten, etc.), and shields the radiation 59 so that the radiation 59 is not irradiated to other than a desired part. The flattening filter 54 is formed of aluminum or the like, and is formed on a plate on which a generally conical protrusion is formed. The flattening filter 54 is disposed so that its protrusion faces the X-ray target side. The flattening filter shape is formed so that the dose in a predetermined region on a plane perpendicular to the radiation direction is distributed substantially uniformly after passing through the flattening filter. The secondary collimator 55 is made of a high atomic number substance (lead, tungsten, etc.), and shields the radiation 60 so that the radiation 60 is not irradiated to other than a desired part. The radiation 60 having a uniform intensity distribution formed in this way is partially shielded by the multi-leaf collimator 56 controlled by the radiation therapy apparatus control apparatus 2 and has a property based on a separately constructed treatment plan. A certain therapeutic radiation 23 is generated. That is, the multi-leaf collimator 56 is controlled by the radiation therapy apparatus control apparatus 2 to control a shape of an irradiation field when the patient is irradiated with the therapeutic radiation 23 by shielding a part of the radiation 60.

  The dosimeter 61 is a transmission ionization chamber that measures the intensity of transmitted radiation, and is disposed between the primary collimator 53 and the secondary collimator 55 so that the radiation 60 is transmitted. The dosimeter 61 measures the dose of the transmitted radiation 60 and outputs the intensity to the radiation therapy apparatus control apparatus 2. Such a dosimeter 61 is preferable in that non-destructive verification is possible. The X-ray intensity detector other than the transmission ionization chamber can be applied to the dosimeter 61. Examples of the X-ray intensity detector include a semiconductor detector and a scintillation detector. The semiconductor detector or the scintillation detector is preferably disposed outside the orbit because it is difficult to substitute the radiation detector on the radiation orbit like a transmission ionization chamber. It is fixed to the traveling gantry 14 so as to be disposed at a position facing the device 16. An ionization chamber generally has a time constant of about several seconds and has poor responsiveness. The semiconductor detector or the scintillation detector has a disadvantage that the signal intensity is lower than that of the ionization chamber when placed outside the orbit, but it is preferable because it has better response than the ionization chamber.

  The electron beam accelerator 51 includes an electron beam generator 63 and an acceleration tube 64. The electron beam generator 63 includes a cathode 66 and a grid 67. The acceleration tube 64 is formed in a cylindrical shape, and includes a plurality of electrodes 68 arranged at appropriate intervals inside the cylinder. The radiotherapy apparatus 3 further includes a cathode power supply 70, a grid power supply 69, and a klystron 5. The cathode power supply 70 is controlled by the radiotherapy device controller 2 so that the cathode 66 is heated and a predetermined amount of electrons are emitted from the cathode 66 (that is, the cathode 66 is maintained at a predetermined temperature). ), Power is supplied to the cathode 66. The grid power supply 69 is controlled by the radiotherapy apparatus control device 2 to apply a predetermined voltage between the grid 67 and the cathode 66 so that only a predetermined amount of electrons are emitted from the electron beam generator 63. . The klystron 5 is connected to the acceleration tube 64 via the waveguide 8. The klystron 5 is controlled by the radiotherapy device controller 2 and is accelerated through the waveguide 8 so that the accelerator tube 64 accelerates electrons emitted from the electron beam generator 63 until it has a predetermined energy. A microwave is incident on 64. The klystron 5 can be replaced with another high-frequency source. Examples of the high frequency source include a magnetron and a multipolar tube.

  FIG. 4 shows the X-ray target 52. The X-ray target 52 is formed on a plate along the conical conical surface. The X-ray target 52 is arranged so that its conical axis 71 coincides with the irradiation axis of the electron beam 57 generated by the electron beam accelerator 51. The X-ray target 52 is formed such that an edge 73 overlaps a plane 72 perpendicular to the axis 71.

  The X-ray target 52 can be partially formed in the shape shown in FIG. 4, that is, in a shape in which another plate-like portion is integrally joined to the edge 73 of the shape shown in FIG. It can also be formed.

  As shown in FIG. 5, the X-ray target 52 includes a cooling device 74. The cooling device 74 is joined to the X-ray target 52 so as to conduct heat to the X-ray target 52. The cooling device 74 has a flow path 75 formed therein. The cooling device 74 cools the X-ray target 52 by flowing cooling water through the flow path 75.

  FIG. 6 shows a method for manufacturing the radiation therapy apparatus 3. The designer first designs the shape of the X-ray target 52 (step S1). The designer grasps and evaluates the calorific value or temperature distribution state of the X-ray target when the created X-ray target is irradiated with an electron beam (step S2), and is emitted from the X-ray target. The radiation dose distribution is grasped and evaluated (step S3). Examples of the grasp evaluation method include an experimental method and a simulation method. In the method based on the experiment, the designer creates an X-ray target formed in the designed shape, irradiates the X-ray target with an electron beam, and generates a calorific value and temperature distribution of the X-ray target. The state is measured, and the dose distribution of radiation emitted from the X-ray target is measured. In the simulation method, the designer creates a mathematical model of the X-ray target formed in the designed shape, simulates that the electron beam is irradiated to the X-ray target, The state of heat generation of the line target is calculated, and the dose distribution of radiation emitted from the X-ray target is calculated.

  When the grasp evaluation result is not appropriate (NO in step S4), the designer executes step S1 again, changes the design of the shape of the X-ray target 52 (step S1), and is again formed into that shape. The state of heat generation or temperature distribution of the X-ray target is grasped and evaluated (step S2), and the dose distribution of radiation emitted from the X-ray target is grasped and evaluated (step S3). That is, the designer repeatedly executes step S1 to step S4 until the evaluation result becomes appropriate.

  When the evaluation result is appropriate (YES in step S4), for example, the X-ray target during irradiation of the electron beam 57 does not become higher than a predetermined temperature and the irradiation axis of the electron beam 57 is set. When the X-ray target emits a high dose of radiation in a narrow area along the X-ray target 52, the X-ray target 52 is manufactured in the designed shape (step S5), and the X-ray generator 16 including the X-ray target 52 is provided. Manufacture (step S6), and manufacture the radiotherapy apparatus 3 including the X-ray generator 16 (step S7).

  FIG. 7 shows the dose of X-rays emitted from the X-ray target 52 when the X-ray target 52 is irradiated with the electron beam 57. In the X-ray target 52, the X-ray emitted from the point 76 near the conical axis 71 has the largest X-ray dose radiated along the axis 71, and the direction in which the angle formed with the axis 71 is larger. The X-ray dose is small. X-rays radiated from a point 77 of the X-ray target 52 away from the axis 71 are radiated along a direction close to the normal direction of the X-ray target 52 in order to attenuate by the X-ray target 52 itself. The dose of X-rays is the largest and the smaller the angle between the X-ray and the direction, the smaller the dose. That is, the X-ray target 52 radiates from the X-ray target 52 by appropriately designing the target angle θ (angle formed by the irradiation direction of the electron beam 57 and the surface of the X-ray target 52) and the thickness d. X-ray dose distribution can be designed. For example, when the X-ray target 52 is convex upstream of the electron beam 57, the X-ray dose distribution can be concentrated on the central axis 71. In addition, high dose rate X-rays can be generated in a narrow range along the irradiation axis of the electron beam 57.

  FIG. 8 shows changes in the X-ray dose rate of the therapeutic radiation 23 irradiated to the isocenter 19 when the target angle θ of the X-ray target formed to a certain thickness is changed. The change 79 is that when the target angle θ is smaller than a certain angle θ1, the X-ray dose rate increases as the target angle θ increases, and when the target angle θ is larger than the angle θ1, the target angle θ increases. It shows that the X-ray dose rate is small. That is, the change 79 indicates that the dose rate of radiation emitted from the X-ray target 52 formed on the curved surface is larger than that of the flat X-ray target. The change 79 further indicates that the dose rate of the radiation emitted from the X-ray target 52 can be improved by appropriately designing the target angle θ of the X-ray target 52.

  That is, the designer of the radiotherapy apparatus 3 performs a flow shown in FIG. 6 to narrow the range along the irradiation axis of the electron beam 57 so as to improve the dose rate of the radiation emitted from the X-ray target 52. In addition, the target angle θ of the X-ray target 52 can be appropriately designed so as to generate a high dose rate X-ray.

  Furthermore, the area of the portion irradiated with the electron beam 57 is larger in the X-ray target 52 than in the flat X-ray target. For this reason, the X-ray target 52 can reduce heat generation per unit area of the portion irradiated with the electron beam 57 as compared with a flat X-ray target. As a result, the X-ray target 52 can increase the dose of the irradiated electron beam 57 and increase the dose of the radiation 59 to be emitted.

  Note that the X-ray target 52 can also be formed in a shape that is convex downstream of the electron beam 57. At this time, the X-ray target 52 cannot concentrate the X-ray dose distribution on the central axis 71, but in the same manner as the X-ray target that is convex upstream of the electron beam 57, Heat generation per unit area of the irradiated portion can be reduced, the dose of the irradiated electron beam 57 can be increased, and the dose of the radiation 59 to be emitted can be increased.

  In radiotherapy using the radiotherapy system 1, a user first creates a treatment plan. The treatment plan shows an irradiation angle at which the affected part of the patient 43 is irradiated with the therapeutic radiation 23 and a dose and a property of the therapeutic radiation 23 irradiated from each irradiation angle. The user fixes the patient 43 to the couch 41 of the radiotherapy device 3. The radiotherapy device control device 2 uses the turning drive device 11, the travel drive device and the couch drive device 42 so that the patient 43 is irradiated with the therapeutic radiation 23 at the irradiation angle indicated by the treatment plan. The line generator 16 and the patient 43 are aligned.

  Next, the radiotherapy device control device 2 repeatedly executes the tracking operation and the irradiation operation. In the tracking operation, the radiation therapy apparatus control device 2 calculates the affected part position based on the image captured by the imager system of the radiation therapy apparatus 3. The radiotherapy apparatus control apparatus 2 drives the X-ray generation apparatus 16 using the swing mechanism 15 so that the therapeutic radiation 23 passes through the affected area. In the irradiation operation, the radiotherapy apparatus control apparatus 2 irradiates the affected part with the therapeutic radiation 23 using the X-ray generation apparatus 16 immediately after the X-ray generation apparatus 16 is moved by the tracking operation.

  Since the radiotherapy apparatus 3 can increase the dose rate of therapeutic radiation that can be generated by the X-ray generator 16, it can reduce the time required for radiotherapy and reduce the burden on the patient. Can do. For example, when it is necessary to hold the breath during radiation irradiation in order to stop the movement of the affected part, the time for the patient 43 to hold the breath can be shortened.

The X-ray target 52 can also be formed in other shapes different from the conical shape.
FIG. 9 shows an X-ray target formed in another shape. The X-ray target 81 is formed on a plate along a spherical surface. The X-ray target 52 is arranged so that the axis 71 of the sphere coincides with the irradiation axis of the electron beam 57 generated by the electron beam accelerator 51. The X-ray target 81 is formed so that the edge 82 overlaps with a plane 72 perpendicular to the axis 71. The X-ray target 81 can improve the dose rate of the radiation radiated from the X-ray target 52 in the same manner as the X-ray target 52 in the above-described embodiment, and the X-ray dose distribution can be obtained at the central axis. The X-ray can be generated at a high dose rate in a narrow range along the irradiation axis of the electron beam 57.

  FIG. 10 shows an X-ray target formed in yet another shape. The X-ray target 83 is formed on a plate along a spheroidal surface formed by rotating an ellipse around an axis 71. At this time, the axis of the ellipse is arranged so as to coincide with the axis 71. The X-ray target 52 is arranged so that the axis 71 of the spheroid plane coincides with the irradiation axis of the electron beam 57 generated by the electron beam accelerator 51. The X-ray target 83 is formed so that the edge 84 overlaps the plane 72 perpendicular to the axis 71. In FIG. 10, the shape of the X-ray target 83 is a spheroid whose major axis of the ellipse coincides with the axis 71, but a spheroid whose minor axis of the ellipse coincides with the axis 71 is applied. Can also be done. The X-ray target 83 can improve the dose rate of the radiation radiated from the X-ray target 52 in the same manner as the X-ray target 52 in the above-described embodiment, and the X-ray dose distribution can be obtained at the central axis. The X-ray can be generated at a high dose rate in a narrow range along the irradiation axis of the electron beam 57.

  FIG. 11 shows an X-ray target formed in yet another shape. The X-ray target 85 is formed on a plate along the pyramid surface of the pyramid. The X-ray target 52 is arranged so that the axis 71 of the pyramid coincides with the irradiation axis of the electron beam 57 generated by the electron beam accelerator 51. The X-ray target 85 is formed so that the edge 86 overlaps a plane 72 perpendicular to the axis 71. The X-ray target 85 can improve the dose rate of the radiation radiated from the X-ray target 52 in the same manner as the X-ray target 52 in the above-described embodiment, and the X-ray dose distribution can be obtained at the central axis. The X-ray can be generated at a high dose rate in a narrow range along the irradiation axis of the electron beam 57.

  FIG. 12 shows an X-ray target formed in yet another shape. The X-ray target 87 is formed on a plate along a curved surface formed by rotating an appropriate figure around an axis 71. The X-ray target 52 is arranged so that its axis 71 coincides with the irradiation axis of the electron beam 57 generated by the electron beam accelerator 51. The X-ray target 87 is formed so that the edge 88 overlaps the plane 72 perpendicular to the axis 71. The X-ray target 87 is further formed so as to be disposed on the electron beam accelerator 51 side from the plane 72. The X-ray target 87 can improve the dose rate of the radiation radiated from the X-ray target 52 in the same manner as the X-ray target 52 in the above-described embodiment, and the X-ray dose distribution can be obtained at the central axis. The X-ray can be generated at a high dose rate in a narrow range along the irradiation axis of the electron beam 57.

  The X-ray target may be formed in a shape other than a shape that is symmetric with respect to a rotation operation that rotates 1 / n around the axis 71 (n is a natural number). The electron beam 57 is generally not symmetric with respect to its irradiation axis. By designing the X-ray target appropriately by executing the flow of FIG. 6, the designer is symmetric with respect to the irradiation axis of the electron beam 57 when the electron beam 57 that is not symmetric with respect to the irradiation axis is irradiated. An X-ray generator that emits radiation can be manufactured. The X-ray target can also be formed into a shape that is formed without cutting and stretching a flat sheet. According to such a shape, the X-ray target can be manufactured only by a process of bending a flat plate, which is preferable.

  FIG. 13 shows an X-ray target formed in yet another shape. The X-ray target 91 includes a first X-ray target 92, a second X-ray target 93, a first cooling device 94, and a second cooling device 95. The first X-ray target 92 is formed in the same shape as the X-ray target 52 in the above-described embodiment, and further formed so that a part of the electron beam 57 is transmitted. The second X-ray target 93 is formed in the same shape as the first X-ray target 92, and is disposed on the downstream side of the electron beam 57 from the first X-ray target 92. The first cooling device 94 is joined to the first X-ray target 92 so as to be able to conduct heat to the first X-ray target 92. The first cooling device 94 has a flow channel 96 formed therein. The first cooling device 94 cools the first X-ray target 92 by flowing cooling water through the flow path 96. The second cooling device 95 is joined to the second X-ray target 93 so as to be able to conduct heat to the second X-ray target 93. The second cooling device 95 has a flow path 97 formed therein. The second cooling device 95 cools the second X-ray target 93 by flowing cooling water through the flow path 97.

  Such an X-ray target 91 has a per unit area of a portion irradiated with the electron beam 57 as compared with a single X-ray target that is irradiated with the electron beam 57 and generates radiation by bremsstrahlung. Heat generation can be reduced. As a result, the X-ray target 91 can increase the dose of the irradiated electron beam 57 and increase the dose of the radiation 59 to be emitted. Note that the X-ray target 91 is an X-ray target that is arranged so that a part of the electron beam passes through the X-ray target and the transmitted electron beam is irradiated to another X-ray target. 3 or more can also be provided. At this time, the X-ray target 91 can similarly reduce the heat generation per unit area of the portion irradiated with the electron beam 57, increase the dose of the irradiated electron beam 57, and emit radiation. The dose of radiation 59 can be increased.

FIG. 1 is a block diagram showing an embodiment of a radiation therapy system according to the present invention. FIG. 2 is a perspective view showing the radiation therapy apparatus. FIG. 3 is a cross-sectional view showing the X-ray generator. FIG. 4 is a perspective view showing an X-ray target. FIG. 5 is a cross-sectional view showing the X-ray target. FIG. 6 is a flowchart showing an embodiment of an X-ray generator manufacturing method according to the present invention. FIG. 7 is a diagram showing the dose of X-rays emitted from the X-ray target when the X-ray target is irradiated with an electron beam. FIG. 8 is a graph showing changes in the X-ray dose rate of therapeutic radiation irradiated to the isocenter when the target angle is changed. FIG. 9 is a perspective view showing another X-ray target. FIG. 10 is a perspective view showing still another X-ray target. FIG. 11 is a perspective view showing still another X-ray target. FIG. 12 is a perspective view showing still another X-ray target. FIG. 13 is a cross-sectional view showing still another X-ray target.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1: Radiation therapy system 2: Radiation therapy apparatus control apparatus 3: Radiation therapy apparatus 5: Klystron 8: Waveguide 11: Turning drive device 12: O-ring 14: Traveling gantry 15: Swing mechanism 16: Apparatus 17: Rotating shaft 18: Rotating axis 19: Isocenter 21: Pan axis 22: Tilt axis 23: Radiation for treatment 24: X-ray source for diagnosis 25: X-ray source for diagnosis 31: Sensor array 32: Sensor array 33: Sensor array 35: For diagnosis X-ray 36: X-ray for diagnosis 41: Couch 42: Couch drive device 43: Patient 51: Electron beam accelerator 52: X-ray target 53: Primary collimator 54: Flattening filter 55: Secondary collimator 56: Multi-leaf collimator 57: Electron beam 58: Virtual point source 59: Radiation 60: Radiation 61: Dosimeter 63: Electricity Line generating unit 64: acceleration tube 66: cathode 67: Grid 68: plural electrodes 69: Grid Power 70: cathode power supply 71: shaft 72: a plane 73: edge 74: Cooling device 75: flow path

Claims (12)

An accelerator that accelerates charged particles;
A target that emits radiation by being irradiated with the charged particles,
The target is a curved surface and includes a portion where an edge is disposed on a plane. X-ray generator. In claim 1,
The said part is convex on the said acceleration device side X-ray generator. In claim 2,
The said part is formed in a rotation object with respect to the axis | shaft parallel to the direction where the said charged particle is irradiated. X-ray generator. In claim 3,
The said part is formed along the cone cone surface. X-ray generator. In claim 3,
The portion is formed along a spherical surface. In claim 3,
The said part is formed along the spheroid. X-ray generator. In claim 2,
The said part is formed along the pyramid surface of a pyramid X-ray generator. In any one of Claims 1-7,
An X-ray generator further comprising a cooling device for cooling the target. In any one of Claims 1-8,
An X-ray generator further comprising: another target that emits radiation when irradiated with charged particles that have passed through the target among the charged particles. An X-ray generator according to any one of claims 1 to 9,
A radiotherapy apparatus comprising: a support device that supports the X-ray generation apparatus so that the radiation is irradiated to a part of a subject. Obtaining a dose distribution of radiation emitted from the target when the target is irradiated with charged particles;
A method of changing the design of the shape of the target based on the dose distribution. Obtaining heat of the target when the target is irradiated with charged particles;
A method for manufacturing an X-ray generator, comprising: redesigning the shape of the target based on the heat generation.

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