JPH05337207A - Localization radiation medical treatment device - Google Patents

Abstract

PURPOSE:To constitute the device so that an irradiation beam can catch exactly a focus part even when a gantry having an irradiation head is rotating by a simple constitution by attaching a localization method collimator to an irradiation visual field formation collimator provided in the irradiation head. CONSTITUTION:In a gantry, an X-ray target 15 for receiving irradiation of an electron beam carried from an electron beam generation source and radiating X rays is provided, and in a irradiation head 20, a movable collimator for forming an irradiation visual field, which forms X rays in a rectangular shape, and can be driven in the x and the y directions is provided, and to one of the irradiation visual field collimators, a localization method collimator 30 is attached. The localization method collimator 30 has a collimating hole 31, can execute a pendulum operation an indicated with the arrow A by a driving means, and also, can be fixed to any position, and the center position of the pendulum operation becomes the apex B of a radiation conical body. Also, the irradiation head 20 can rotate by setting the radiation radial direction as an axis, and simultaneously with the pendulum motion of the static method collimator, the irradiation head 20 is rotated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to stereotactic radiotherapy in which a narrow radiation beam is stereotactically focused on a single point for treatment, and in particular, the mechanical precision of a gantry for irradiating radiation is reduced, and The present invention relates to a stereotactic radiotherapy apparatus suitable for accurately concentrating radiation on a localized point for any lesion.

[0002]

2. Description of the Related Art One of the radiotherapy techniques is a radiation irradiation method called stereotactic radiotherapy (localization method). The localization method is a method of locally irradiating a lesion with a large dose, and a method of concentrating and irradiating a focal point with a very thin radiation beam. This localization method is very effective in treating malignant tumors and has an effect of significantly reducing radiation exposure to surrounding normal tissues. The stereotactic method administers a much higher dose to the lesion than conventional radiotherapy. Therefore, when the irradiation is accurately focused on the lesion, a large therapeutic effect can be expected, but if the irradiation position deviates from the lesion, damage to normal tissue will be great, and It can be deadly as well. Therefore, a stereotactic radiotherapy apparatus that performs this localization method is required to always and surely match the irradiation position with the position of the lesion with extremely high accuracy. As such a positioning method, another diagnostic device (C
T, MRI, simulator, etc.) to measure the lesion position,
A method is adopted in which the measured lesion position is made to coincide with the focus of the therapeutic radiation beam of the stereotactic radiotherapy apparatus, that is, the isocenter, and irradiation is started.

As a stereotactic radiotherapy apparatus, a multi-source radiotherapy apparatus called a gamma unit, a single-source radiotherapy apparatus using an electron beam accelerator, etc. (Japanese Patent Publication No. 2-5).
03521). The former is composed of a hemispherical collimator having a large number of irradiation holes and a cobalt 60 sealed source placed outside the collimator, and gamma doses from a large number of hemispherical cobalt 60 sources are concentrated on the lesion. It is possible to realize the treatment by being added. On the other hand, in the latter, an electron beam accelerator or the like can be used to rotate the gantry around the lesion of the patient and also rotate the treatment table to intensively irradiate the lesion with radiation from all directions. Therefore, a large dose can be given to the lesion site as an integrated dose thereof, and a low dose can be given to a normal tissue by the dose dispersion effect. However, in the case of the former, a large number (about 200) of cobalt 60 is used as a radiation source, and the cobalt 60 has a half-life, so replacement is required, which causes maintenance costs and management problems. The high price of the device makes it difficult to spread. Also, the former gamma unit is for the head only, and is not suitable for the chest and abdomen where the lesion moves due to breathing. Therefore, stereotactic radiotherapy using the latter electron beam accelerator is expected.

The case of performing stereotactic radiotherapy with this electron beam accelerator will be outlined with reference to FIG. The gantry 1 of the electron beam accelerator device rotates about a horizontal axis 7, and the radiation is provided on the gantry 1 supported by the support portion 5.
The beam passes through the irradiation head 2 and is collimated by the stereotactic radiotherapy collimator 3 to irradiate the lesion on the patient 10 with the beam. The intersection 8 of the horizontal axis 7 and the center (vertical axis) 6 of the beam emitted by the collimator 3 is the isocenter 0.
The patient's lesion is aligned with this position. Further, the beam center irradiated while the gantry 1 rotates about the horizontal axis 7 must always be able to catch the intersection 8. As a means for this, the collimator 3 attached to the irradiation head 2 is used.
There is also a way of thinking that the radiation emission direction can be changed by moving with respect to. Then, the rotation of the gantry 1 and the rotation of the treatment table 4 are combined to operate, and radiation can be applied to the lesion from all directions.

[0005]

Since the gantry of the stereotactic radiotherapy apparatus using an electron beam accelerator and the irradiation head provided on the gantry are heavy objects, the gantry is, for example, as shown by the dotted lines in FIGS. 6 and 7. During the rotation, there is backlash or bending, and the beam center cannot catch the lesion, and the center beam 6 of the radiation beam is displaced during the rotation, and the beams 11 and 12 cannot pass through.
Despite careful positioning as described above, treatment in such a state reduces the ratio of the dose to the lesion and the dose to normal tissue, reducing the effect of destroying the lesion. Moreover, there is a risk that even normal tissue will be destroyed. Moreover, for the chest and abdomen where the lesion moves due to breathing, moving the irradiation head, which is a heavy object, in accordance with the movement of the lesion causes poor followability and increases the size of the apparatus.

It is an object of the present invention to provide a stereotactic radiotherapy apparatus having a simple mechanism and capable of accurately capturing a lesion with an irradiation beam even when a gantry having an irradiation head is rotating.

[0007]

According to the present invention, a localization method collimator is attached to a conventional irradiation field forming collimator provided in an irradiation head (claim 1). Further, the present invention controls the positional deviation of the localization method collimator by using the control system of the localization method collimator (claim 2). Further, in the present invention, the first and second localization method collimator leaves having oblique slit holes are attached to the irradiation field forming collimator, and the slit holes are moved by the movement of the first and second localization method collimator leaves. The position of the intersecting point collimating hole is controlled (claim 3).

Further, according to the present invention, the first and second localization collimator leaves having oblique slit holes are attached to a place other than the irradiation field forming collimator (claim 4).

According to the present invention, a stereotactic radiotherapy apparatus can be realized by simply attaching a localization method collimator to an irradiation field forming collimator in an existing radiotherapy apparatus (claims 1 to 3).

Further, according to the present invention, a collimator leaf having two oblique slit holes is used as a collimator for the localization method, and the collimator hole at the intersection is two-dimensionally moved to position the collimator hole at the isocenter. Perform (claim 3).

Further, the localization method collimator leaf can be positioned at the isocenter even if it is attached to a place other than the irradiation field forming collimator (claim 4).

[0012]

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. This stereotactic radiotherapy apparatus includes a gantry 1 that is supported by a support 5 and rotates around a patient 10 around a horizontal axis 7, and an irradiation head that is supported by the gantry 1 and is rotatable about a vertical axis 7. 20, a treatment table (bed) 4, and a collimator 30 for localization method.
The gantry 1 has an X-ray target 1 that emits X-rays by being irradiated with an electron beam carried from an electron beam generation source 16.
5 is provided, and the irradiation head 20 is provided with a movable collimator for forming an irradiation field that can drive the x and y directions in a rectangular shape. The irradiation head 20 is a part of a conventional radiotherapy device. The irradiation field forming collimator is x, which can be driven independently in the x and y directions.
The y-collimator is a rectangular space sandwiched by the collimators and serves as an irradiation field. This space has various sizes by variously changing the positions of the x and y collimators, and the irradiation visual field is controlled. This control is performed by the control system. In this embodiment, the localization method collimator 30 is attached to one of the irradiation field collimators of the irradiation head 20.

In the state shown in FIG. 4, the intersection 8 between the vertical axis 6 which is the X-ray irradiation center and the horizontal axis 7 which is the rotation center of the gantry 1 becomes the isocenter 0, so that the lesion part can be aligned with this position. , Move the treatment table up and down, left and right to position it. The treatment table 4 is fixedly attached to a turntable 14 rotatably installed on a horizontal plane about a vertical axis 6 passing through the isocenter 0.
Thus, with the rotation of the turntable 14, the treatment table can rotate on the horizontal plane about the isocenter 0.

FIG. 1 shows an embodiment of the irradiation head 20 and the collimator 30 for localization method. Movable collimator 17, 18
Is a collimator for forming an irradiation field, and x and y respectively
Are arranged in the direction. The movable collimators 17 and 18 are
Each is composed of two collimator leaves, and by arranging these four collimator leaves in a rectangular shape in the x and y directions, a rectangular X-ray passage is formed. The size of the rectangular shape is adjusted by changing the distance between the four collimator leaves. However, conventionally, the movable collimator 17,
No. 18 merely narrows the radiation into a rectangle and does not correct the positional deviation with respect to one localized point. Therefore, the (18B) localization method collimator 30 is attached to at least one of the collimator leaves 18A and 18B of the movable collimator 18 provided on the outlet side via the support portion 19.
The localization method collimator 30 has a collimating hole 31 for thinning the radiation to a sufficient extent for performing the localization method.
The driving means (not shown) of the movable collimator 18B enables a pendulum operation (movement from 0 to 0 ') as shown by an arrow A in FIG. 1 and can be fixed at any position. Furthermore, the center position of the pendulum operation is the vertex of the radiation weight body (X-ray target 1
Center position 5) B. The center line of the collimating hole 31 is on a straight line connecting the apex B of the radiation cone and the isocenter so that the dose distribution of the radiation emitted from the collimating hole 31 is constant regardless of the position of the pendulum operation. Exists.

Here, the radiation weight cone means the target 1
5, the vertex is the radiation position of the target 15, and in the case of a point radiation source, the position of the point itself, and in the case of a surface radiation source, the center position of the surface. The irradiation head 20 is rotatable about the radiation direction, and the irradiation head can be rotated simultaneously with the pendulum movement of the localization method collimator. The pendulum motion of the localization method collimator is performed by a movable collimator drive device that constitutes a control system, and the irradiation head is rotated by an irradiation head rotation mechanism.

If the irradiation head rotates in this way and the pendulum operation of the collimating hole 31 is enabled, the center line of the collimating hole 31 is always located at the apex of the radiation cone and the isocenter by combining these two operations. Can be aligned on a straight line. Therefore, when the gantry and the irradiation head are tilted as shown by the dotted lines in FIGS. 6 and 7 and the center line for the localization method collimates to positions 11 and 12, the localization method collimator is moved to move the collimator holes. It can be corrected so that the central axis coincides with the straight line connecting the apex of the radiation cone and the isocenter.

FIG. 2 shows leaves 18A, 18B of a movable collimator 18 for conventional radiation therapy, which is usually a pair of two.
18A, one of which is provided with a collimator for localization method 32 in which a slit hole 32A is obliquely provided, and another collimator leaf 18B is provided with a slit hole 33A at an angle different from that of the slit for another localization method. Collimator 33
It is the example which attached. Movable collimator leaf 1
By moving 8A and 18B separately, the collimating hole 35 formed by the intersection of the two slit holes 32A and 33A moves two-dimensionally.

FIG. 3 is a view of the localization method collimator of FIG. 2 seen from below. This principle is shown in FIG. The localization method collimators 32 and 33 have slit holes 32 as shown in FIG.
A and 33A are open. Place x and y coordinates around the isocenter as shown. FIG. 3B shows the reference state, and the collimating hole 35 is on the isocenter. FIG. 3C shows a case where both movable collimator leaves 18A and 18B are separated. At this time, the collimating hole 35 moves in the negative direction along the y-axis. In contrast to the case (3), FIG. 3 (4) shows a case where both movable collimator leaves 18A and 18B are pressed. At this time, the collimating hole 35 moves in the positive direction along the y-axis. FIGS. 3 (5) and 3 (6) show the case where the movable collimator leaves 18A and 18B are both moved in the same direction, and the collimating hole 35 is moved in the negative or positive direction along the x axis. become. In this way, the direction of the radiation can be changed while keeping the size of the collimating hole constant. Therefore, when the positional deviation occurs, the collimator hole 35 is moved so as to correct the positional deviation, and the positional deviation is corrected.

In each of the above-described embodiments, the collimator for localization method is attached to the movable collimator for forming the irradiation field, and the positional deviation is corrected by utilizing the control system thereof. Movable collimators include general ones that form a rectangular area in the x and y directions, and multi-divided movable collimators on the lower side, both of which are for the localization method. A collimator can be attached. Furthermore, in these embodiments, one movable collimator for forming the irradiation field is not used for forming the original irradiation field. Instead of mounting it on one of the movable collimators, as in the conventional example of FIG. 5, a localization method collimator (in particular, a collimator as shown in FIG. 2) is independently provided on the irradiation head to control it. The rectangular area can be formed by the movable collimator and the collimator for localization can be realized. Although the example of correcting the positional deviation has been described, it goes without saying that it can also be used for position control.

Further, the slit 2 as shown in FIG.
The three localization collimators can also be used as collimators other than the localization method. If the width of the slit hole is increased, the collimator hole 35 can be increased, and the collimator hole 35 can be used for a conventional radiotherapy device. It can also be used as a collimator such as an X-ray CT apparatus.

[0021]

According to the present invention, when the therapeutic gantry is rotated and the positional deviation occurs from a localized point due to backlash or flexure as described above, the collimator is driven by the collimator drive means. The collimator is moved so that the central axis of the hole of the collimator is aligned with the straight line connecting the apex of the radiation weight cone and the isocenter. As a result, the central axis of the radiation passes through the isocenter, and the dose distribution of the radiation emitted from the holes of the collimator becomes constant. In this way, the radiation can be always focused on one localized point even when the therapeutic gantry is rotating.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of an irradiation head and a collimator for localization method of the present invention.

FIG. 2 is a diagram of another embodiment of the collimator for localization method of the present invention.

FIG. 3 is a diagram showing an example of two-dimensional movement of a localization method collimator of the present invention.

FIG. 4 is a diagram showing the entire embodiment of the stereotactic radiotherapy apparatus of the present invention.

FIG. 5 shows a conventional stereotactic radiotherapy apparatus.

FIG. 6 is a diagram showing the deflection of a gantry.

FIG. 7 is a diagram showing deflection of a gantry.

[Explanation of symbols]

 1 Gantry 2 Irradiation head 3 Stereotactic collimator 4 Treatment table (bed) 5 Gantry support 6 Vertical axis 7 Horizontal axis 10 Patient 14 Rotating disk 15 X-ray target 17 Irradiation field forming collimator 18 Irradiation field forming collimator 18A, 18B Leaf 20 of collimator 18 Irradiation head 30 Collimator for localization method 31 Collimation hole 32 Collimator for localization method 32A, 33A Slit hole 33 Collimator for localization method 35 Collimation hole

Claims (4)

[Claims] 1. A high energy electron generator, a carrier system for carrying the generated electron beam, a conversion means for converting the electron beam into X-rays, and a movable collimator for forming an X-ray irradiation field. , A gantry for treatment rotatably supported about a horizontal axis, an irradiation head supported by the gantry for treatment having a movable collimator for forming an X-ray irradiation field, and rotating about a vertical axis. A stereotactic radiotherapy apparatus comprising a treatment table, and a collimator for localization method having a collimating hole attached to the movable collimator for forming the irradiation field. 2. The stereotactic radiotherapy apparatus according to claim 1, wherein when the irradiation X-rays deviate from the lesion, the movable collimator is controlled by using a control system for forming an irradiation field of the movable collimator for radiotherapy. A stereotactic radiotherapy device that controls the collimator holes of a collimator for stereotactic method toward the lesion so that the irradiated X-rays always capture the lesion by moving. 3. The stereotactic radiotherapy apparatus according to claim 1 or 2, wherein the movable collimator for radiotherapy comprises first and second collimator leaves, and the first collimator leaf is provided with a slit hole obliquely. A first localization method collimator is attached, and a second localization method collimator in which a slit hole is obliquely provided at an angle different from the slit is attached to the second collimator leaf, and a collimator is formed by intersecting two slit holes. A stereotactic radiotherapy apparatus in which the first and second movable collimator leaves are separately moved so that the holes move two-dimensionally. 4. A high energy electron generator, a carrier system for carrying the generated electron beam, a conversion means for converting the electron beam into X-rays, and a movable collimator for forming an X-ray irradiation field. , A gantry for treatment rotatably supported about a horizontal axis, an irradiation head supported by the gantry for treatment having a movable collimator for forming an X-ray irradiation field, and rotating about a vertical axis. And a treatment table and a collimator for localization method having a collimating hole,
The localization collimator includes a first collimator leaf having an oblique slit hole and a second collimator leaf having an oblique slit hole at an angle different from the slit hole.
Two collimating holes formed by intersecting two slit holes
A stereotactic radiotherapy apparatus comprising: a mechanism capable of moving the first and second collimator leaves separately so as to move dimensionally.