JP2593412Y2 - Stereotactic radiotherapy device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stereotactic radiotherapy apparatus for stereoscopically concentrating a narrow beam of radiation at one point, and particularly to a mechanical accuracy of a gantry for irradiating radiation. The present invention relates to a stereotactic radiotherapy apparatus suitable for accurately concentrating radiation on a localized point at any lesion.

[0002]

2. Description of the Related Art A radiation irradiation method called a stereotactic method is a treatment aiming at destruction of a lesion by applying a high dose to a lesion only in multiple directions using a narrow beam of radiation. However, since the irradiation of radiation to the normal part around the part destroyed by this treatment is extremely reduced, there is an effect of eliminating the adverse effect on the normal part.

[0003] Stereotactic radiotherapy devices include a multi-source radiotherapy device called a gamma unit and a single-source radiotherapy device using an electron accelerator or the like (Japanese Patent Publication No. 2-503521).

The former comprises a hemispherical collimator having a large number of irradiation holes, and a cobalt 60 sealed source disposed outside the collimator. It can be applied intensively to the lesion to achieve treatment. On the other hand, in the latter case, the gantry can be rotated around the lesion of the patient by using an electron accelerator or the like, and the lesion can be intensively irradiated from all directions while rotating the treatment table. Therefore, in both cases, a large dose can be given as an integrated dose to a lesion, and a low dose can be given to a normal tissue due to the dispersion effect of the dose.

However, in the former case, a large number (about 200) of cobalt 60 is used as a radiation source, and since cobalt 60 has a half-life, it needs to be replaced. The problem described above, and the high price of the device, make it difficult to spread. In addition, the former gamma unit is used exclusively for the head, and is not suitable for the thorax and abdomen where the lesion moves due to respiration. For this reason, stereotactic radiotherapy using the latter electron accelerator is expected.
The case of performing stereotactic radiotherapy using an electron accelerator will be outlined with reference to FIGS. The gantry 102 of the electron accelerator device rotates around a horizontal axis 123, and the radiation passes through an irradiation head 113 provided on the gantry 102,
The beam is narrowed and irradiated to the lesion. An intersection point 120 between the horizontal axis 123 and the center 121 of the beam emitted from the collimator is an isocenter, and the lesion of the patient matches this position. The center of the beam irradiated while the gantry 102 is rotating about the horizontal axis 123 must always be able to catch the intersection point 120. The rotation of the gantry 102 and the treatment table 11
2 can be operated by combining the rotations in the horizontal plane, and the lesion can be irradiated with radiation from all directions.

[0006]

However, since the gantry and the provided irradiation head are heavy, for example, FIG.
As shown by dotted lines in FIG. 7 and FIG. 7, rattling and deflection occur during rotation of the gantry, and the beam center cannot capture the focus, and during the rotation, the focal point of the radiation beam passes through the isocenter, such as 120a or 120b. Disappears. When the treatment is performed in such a state, the dose ratio to the lesion and the dose to the normal tissue are reduced, so that the effect of destroying the lesion is reduced, and there is a risk that the normal tissue is destroyed. .

[0007] The applicant of the present application has already filed a patent application for correcting backlash and deflection of a gantry (Japanese Patent Application No. Hei.
-25799). Japanese Patent Application No. Hei 4-25799 discloses a stereotaxic system in which a collimator for localization is provided in a housing, the housing is fixed to an irradiation head, the collimator for localization is slidable inside the housing, and the collimator for localization is a wire pyramid. The link mechanism is positioned in the direction. Thereby, the localization collimator can be oriented in the direction coinciding with the isocenter by sliding. Just by pointing in this coincidence direction, the collimator for localization automatically aligns its radiation irradiation center with the isocenter by the link mechanism. .

An object of the present invention is to provide a stereotactic radiotherapy apparatus which enables the same purpose as that of Japanese Patent Application No. 4-25799 to be realized by different means.

[0009]

According to the present invention, there is provided a gantry rotating about a horizontal axis, and supported by the gantry,
In a stereotactic radiotherapy apparatus comprising: an irradiation head that emits radiation in the direction of an isocenter, and a collimator provided to face the irradiation head and having a hole that guides the radiation to the isocenter, the collimator is internally provided. Provided, a collimator housing fixedly provided on the radiation outlet side of the irradiation head, a sliding portion slidable two-dimensionally in the housing, and the collimator portion provided in the housing. A spherical bearing for swingably supporting the sliding portion, and an equispaced position around the collimator portion and the corresponding housing, the housing being supported in the direction of the vertex of the linear cone. And a plurality of connecting portions between the body and the collimator portion.

[0010]

According to the present invention, when the therapeutic gantry rotates while the therapeutic gantry is displaced from one localized point due to backlash or deflection, the collimator is moved by using the collimator position correcting mechanism. Thus, the central axis of the hole of the collimator can coincide with the straight line connecting the vertex of the radiation cone and the isocenter. As a result, the central axis of the radiation always passes through the isocenter, and the dose distribution of the radiation radiated from the hole of the collimator becomes constant. In this way, the radiation can be always concentrated on one localized point even when the treatment gantry is rotating.

Accordingly, a large dose can be given to a lesion as an integrated dose, and a low dose can be given to a normal tissue due to a dose dispersion effect. As a result, the influence of radiation on normal tissues is reduced, and the lesion can be reliably destroyed, so that the therapeutic effect of radiation is maximized.

Further, according to the present invention, by providing a plurality of connecting portions for connecting the housing and the collimator portion, which are supported in the direction of the wire cone, the displacement of the gantry due to backlash or deflection is provided. Corrections can be made quickly and accurately.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 4 is an overall configuration diagram of the stereotactic radiotherapy apparatus of the present invention. The apparatus is supported by a support 1 and rotates around a patient 8 as indicated by an arrow 20, a gantry 2, an irradiation head 10 supported by the gantry 2, and an irradiation head 1.
The collimator driving device 18 is supported by the treatment table 9 on which the patient 8 rests. The gantry 2 and the irradiation head 10 are provided at a transport path 4 for transporting an electron beam 3 from an electron beam source (not shown), a deflection magnet 5 for deflecting the electron beam 3, and an exit of the electron beam 3. Vacuum window 6, an X-ray target 7 that emits X-rays when irradiated with the electron beam 3, a conical collimator 11 that narrows down the emitted X-rays, and movable collimators 12, 13, between the conical collimator 11 and the movable collimator 12. The filter 14 is provided. The filter 14 is a flattening filter that makes the X-ray dose distribution in the cone uniform.

In the state shown in FIG. 4, the intersection of the vertical axis 16 serving as the X-ray irradiation center and the horizontal axis 17 serving as the center of rotation of the gantry 2 becomes the isocenter 15, and the focus of cancer or the like is adjusted to this position. For this purpose, positioning is performed while moving the treatment table up and down and left and right. The treatment table 9 is fixedly attached to a periphery of a turntable 25 which is rotatable on a horizontal plane about a vertical axis 16 passing through the isocenter 15. Thus, with the rotation of the turntable 25, the treatment table can rotate on a horizontal plane about the isocenter 15. The cart 21 is provided for its rotation.

The movable collimators 12 and 13 each have 2
The four collimator blocks are arranged in a rectangular shape in the x and y directions to form a rectangular X-ray passage. The size of the rectangular shape is
The adjustment is performed by changing the distance between the four collimator blocks. However, the movable collimators 12 and 13 merely serve to narrow the radiation to a rectangular shape, and cannot perform an operation of correcting a positional deviation with respect to one localized point. For this purpose, a collimator 19 for localization is provided between the irradiation head 10 and the isocenter 15.

The collimator 19 is a conventional single-source type.
Although fixed to the irradiation head 10, in this embodiment, the collimator 19 is housed in the housing. This embodiment is shown in FIG.
Shown in First, the outline of FIG. 1 will be described. A housing 24 in which a collimator 19 is housed is fixed to the irradiation head 10. The housing 24 incorporates a drive mechanism for driving the collimator 19. The collimator 19 has a hole (referred to as a collimator hole) 43 for further reducing the radiation passing through the movable collimator 13. The collimator 19 can swing about a fulcrum, and can be fixed (positioned) at any swing position. Further, the fulcrum position of the swing is the vertex S of the radiation ray cone. At any position of the swing, the center line 29 of the hole of the collimator is on a straight line connecting the vertex S of the radiation cone and the isocenter so that the dose distribution of the radiation emitted from the collimator hole 43 is constant. Exists. Here, the radiation ray cone is a radiation beam emitted from the target 7, and the vertex is the radiation position of the target 7, and if it is a point radiation source, the position of the point itself, the surface radiation If it is a source, it indicates the center position of the surface.

FIG. 1 is an embodiment of a collimator mechanism incorporating a localization collimator, and FIG. 2 is a sectional view taken along line AA of FIG. The collimator mechanism includes a collimator section 60, a link mechanism L, a swing mechanism K, and a drive mechanism P.

The collimator section 60 includes a collimator 19,
It comprises a cylindrical member 70 for accommodating this. The cylindrical member 70 is
It is provided for the purpose of supporting and protecting the collimator 19, and the collimator 19 is housed therein. However, only the collimator 19 itself may be used except for the cylindrical member 70.

The driving mechanism P includes first, second and third planar members 31, 34 and 36, linear guide rollers 33 and 35, a motor 53, a ball screw 51, and a connecting portion 52. The plane member 31 has a hole 30 as a radiation passage port of the housing 24.
Is a member having the same hole 32 as that described above, and is fixedly attached to the housing 24. On the first flat member 31, a second flat member 34 is attached via a linear guide roller 33 so as to be slidable in the Y direction. A third plane member 36 is mounted on the second plane member 34 via a linear guide roller 35 so as to be swingable in the X direction. That is, the second plane member 34 and the third plane member 36 constitute a generally known XY table. Further, the third flat member 36 has an arm 50 fitted on the ball screw 51, and the third flat member 36 is rotated by rotating the ball screw 51 via the connecting portion 52 by the motor 53.
Can be moved in the X direction. Second plane member 3
4 also has an independent moving mechanism (not shown) similar to the moving mechanism of the third flat member 36, and can move in the Y direction.

The swing mechanism K includes a cylindrical member 70, a spherical bearing 7
1, a housing 73, and a holding member 72. The cylindrical member 70 stores the collimator 19 and is inserted into a spherical bearing 71 having an inner diameter substantially equal to the outer diameter of the cylindrical member 70. The spherical bearing 71 is fixed by a housing 73 and a pressing member 72. The housing 73 is fixed to the third flat member 36.

The link mechanism L includes a rod end 77, a fastening member 78, a connecting shaft 79, a rod end 80, and a fastening member 8.
1, 83, shaft 82, bearing member 84, fastening members 86, 8
7. Consisting of spherical bearings 92 and 93. The mechanism L is connected to the housing 24 via a shaft 82 and also to the swing mechanism L via a shaft 75. That is, one of the shafts 82
The other of the shafts 82 is fixed to a rod end 80 having a spherical bearing 92 via a fastening member 81, thereby being fixed to a bearing member 84 fixed to the housing 24 via a fastening member 81, thereby linking via the shaft 82. The mechanism L is connected to the housing 24. Further, one of the shafts 75 is connected to an arm 74 fixed to the cylindrical member 70, and the other of the shaft 75 is fixed to a rod end 77 having a spherical bearing 93 via a fastening member 78,
Thus, the link mechanism L is connected to the swing mechanism K via the shaft 82. The rod ends 80 and 77 are connected to the connecting shaft 7
9 are connected. The connecting shaft 79 is threaded at both ends and inserted into the threaded portions of the rod ends 70 and 80 so that the connecting shaft 79 is not rotated by the fastening members 86 and 87.

As shown in FIG. 2, the link mechanism L shown in FIG.
Use them individually. Reference numerals 79a, 79b, and 79c denote connection shafts 79 of the three link mechanisms. 2 examples or 4
There can be more than one example.

The second plane member 34 and the third plane member 36
Move in parallel, while the collimator 19 tilts by the link mechanism. The function for smoothly performing the tilting operation is provided by the swing mechanism K. When the center line 29 of the hole 43 of the collimator 19 coincides with the vertical axis line 16 in FIG. 4, the link mechanism is attached to the center axis 90a of the connecting shafts 79a to 79c connecting the rod ends 77 and 80. 90c pass through the vertex S of the ray cone of radiation. That is,
For example, in the case of X-rays, the center point S of the X-ray target 7
It should just be arranged so that it may face.

Next, the operation of this configuration will be described. When the ball screw 51 is rotated by the rotation of the motor 53, the third flat member 36 protrudes, and the arm 50 fitted to the ball screw 51 operates in the direction of the arrow 56.
Similarly, the third flat member 36 is operated by the linear guide roller 35 in the direction of the arrow 56 in parallel with the first flat member 31.
The swing mechanism K fixed to the third plane member 36 also moves. Therefore, the collimator 19 also moves in the direction of the arrow 56 in parallel. However, the part that originally translates is restricted by the link mechanism L that supports the collimator 19, and the collimator 19 is tiltable as shown in FIG. The tilt angle is proportional to the amount of movement of the third planar member 36, and the center line 57 of the collimator hole 43 when it is tilted always passes through the vertex of the radiation cone. The same applies to the case where the second plane member 34 moves in the direction orthogonal to the plane of the paper, that is, in the Y direction. Therefore, the same result is obtained in the combined operation of the second plane member 34 and the third plane member 36. With the configuration of the present invention, the center line of the collimator hole in the case of tilting is always a line of radiation. Can pass through the vertices of the cone.

Therefore, when the gantry 2 and the irradiation head 10 are inclined as shown in FIG. 5 and the center line (radiation center) of the collimator 19 becomes like the line 58, the collimator 19 is operated as described above and the collimator 19 is operated. By inclining 19 as 19a, the position can be corrected so that the central axis 59 of the hole of the collimator coincides with the straight line connecting the vertex of the radiation cone and the isocenter 15.

[0026]

According to the present invention, when a displacement occurs from one localized point due to backlash or deflection while the treatment gantry is rotating, the collimator is provided by using the position correction mechanism of the collimator. Is moved so that the center axis of the hole of the collimator coincides with the straight line connecting the vertex isocenters of the radiation cones. As a result, the central axis of the radiation passes through the isocenter, and the dose distribution of the radiation radiated from the hole of the collimator becomes constant. In this way, even when the treatment gantry is rotating, the radiation can be always concentrated on one localized position.

Therefore, a large dose can be given to the lesion as an integrated dose, and the dose can be reduced to a normal tissue by the effect of dispersion of dose, that is, the influence of radiation on normal tissue is small. And the lesion can be reliably destroyed, and the therapeutic effect of the radiation is maximized.

Further, since the housing and the collimator are connected by the connecting shaft, the position can be corrected quickly and accurately.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment of the collimator mechanism of the present invention.

FIG. 2 is another sectional view of the embodiment of the collimator mechanism of the present invention.

FIG. 3 is a diagram illustrating an example of an operation drive of the embodiment of the collimator mechanism of the present invention.

FIG. 4 is an embodiment of the treatment device of the present invention.

FIG. 5 is an explanatory diagram of positional displacement of a gantry and an irradiation head and their offset.

FIG. 6 is an explanatory diagram of a positional shift of the stereotactic radiotherapy apparatus.

FIG. 7 is an explanatory diagram of a positional shift of the stereotactic radiotherapy apparatus.

[Explanation of symbols]

 2 Gantry 7 Target 9 Bed 10 Irradiation head 15 Isocenter 19 Collimator L Link mechanism K Swing mechanism P Drive mechanism

Claims (1)

(57) [Scope of request for utility model registration] 1. A gantry rotating about a horizontal axis, an irradiation head supported by the gantry and emitting radiation in an isocenter direction, and a hole provided to face the irradiation head and guiding the radiation to the isocenter. A collimator unit having: a collimator unit having the collimator unit provided therein, and a collimator housing fixedly provided on the radiation exit side of the irradiation head; and a two-dimensional interior of the housing. A slidable sliding portion; a spherical bearing provided in the housing; and a spherical bearing for swingably supporting the sliding portion; and an equidistant position around the collimator and the corresponding housing. Combined with the body, supported in the direction of the line cone vertex direction,
A stereotactic radiotherapy apparatus, comprising: a plurality of connecting portions of a housing and a collimator unit.