JP2009207581A - Radiotherapy apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiotherapy apparatus can reduce an occupancy space and performing treatment without raising the position of a subject. <P>SOLUTION: The radiotherapy apparatus is provided with an electron accelerator microtron and a treating table which are mounted on a floor surface, the electron accelerator microtron is arranged by inclining the output side of the radiation beam to the side of the treating table, and the treating table is configured such that the top plate is rotated without interfering with the microtron electron accelerator within a plane horizontal to the floor surface. The radiation beam is irradiated so as to cross the rotary axis of the top plate. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a radiotherapy apparatus that irradiates a lesion of a subject with small-diameter radiation from various directions.

  Such a radiotherapy apparatus can suppress the influence of radiation on the skin around the subject or the healthy tissue, and can increase the radiation dose to the lesion.

  An example of such an apparatus is disclosed in Patent Document 1 below. That is, a small linear electron accelerator that outputs thin X-rays from a small-diameter collimator is provided in an articulated robot, and thin X-rays are emitted toward one point called an isocenter by drive control of the articulated robot. ing.

  In this case, the energy of the X-rays output from the linear electron accelerator is as low as 6 MV, and as shown in the graph of FIG. 7, the depth dose distribution in water has a peak of about 1 to 2 cm from the surface. . In the graph of FIG. 7, the horizontal axis represents water depth (cm) and the vertical axis represents dose (%).

  When the lesion is in the deep part, the higher the energy X-ray, the more the dose in the deep part is relatively increased, which is advantageous with respect to the dose concentration in the deep part. For example, in the case of 50 MV X-rays, the depth is about 5 cm from the surface as shown in FIG. Further, when normalized by comparing each peak of 6 MV and 50 MV as 100%, the dose at a depth of 10 cm is approximately 90% in the case of 50 MV, and approximately 70% in the case of 6 MV. For this reason, the higher the energy X-rays reach to the deep part, which is suitable for the treatment of deep lesions.

  FIG. 8 shows that when the X-rays cannot reach the deep part, the dose in the central part can be increased by irradiating the lesion from the back side of the subject.

On the other hand, as a radiotherapy apparatus for irradiating X-rays from several MV to several tens of MV, there is one using a microtron electron accelerator as disclosed in, for example, Patent Document 2 below. That is, the microtron electron accelerator placed on a floor surface is arranged so that an irradiation port irradiated with an electron beam of desired energy is directed to a subject lying on a treatment table, and the microtron electron accelerator The irradiation port can be rotated around the body axis of the subject by the rotation.
Adler JR Jr, Chang SD, Murphy MJ, et al; Stereotactic and functional neurosurgery; 69 (1-4 Pt 2) 124-128 1997 JP 7-169600 A

  However, in the case where the above-described radiotherapy apparatus is installed in a hospital room, the existing apparatus is often replaced and updated rather than the case where the apparatus is newly installed.

  In this case, since the old model before the update is often small and the radiotherapy apparatus to be updated is large, there is a possibility that the room to be installed must be expanded.

  The room where the radiation therapy apparatus is installed consists of a radiation shielding room surrounded by a concrete wall with a thickness of more than 1 m, and is usually provided in the basement of a hospital. Requires labor and cost.

  Further, in order to carry out the above stereotaxic irradiation of X-rays, it is necessary to arrange the subject so that the lesion coincides with the intersection (isocenter) of the rotation axis of the gantry and the rotation axis of the treatment table, In such a case, the position of the subject becomes relatively high. This increases the risk of health damage due to falling from the patient's treatment table.

  An object of the present invention is to provide a radiotherapy apparatus that can reduce the occupied space and can perform treatment without increasing the position of the subject.

   Of the inventions disclosed in this application, the outline of typical ones will be briefly described as follows.

(1) A radiotherapy apparatus according to the present invention includes, for example, an electron accelerator microtron and a treatment table placed on a floor surface,
The electron accelerator microtron is disposed with its radiation beam output side inclined to the treatment table side,
The treatment table is configured such that its top plate rotates in a plane parallel to the floor surface without interfering with the microtron electron accelerator,
The radiation beam is irradiated so as to intersect with a rotation axis of the top plate.

(2) The radiotherapy apparatus according to the present invention is premised on the configuration of (1), for example, and the radiation beam is irradiated from the electron accelerator microtron so as to intersect the rotation axis of the top plate by a single beam. It is characterized by being.

(3) The radiotherapy apparatus according to the present invention is based on the configuration of (1), for example, and the radiation beam is branched into a plurality of beams from the electron accelerator microtron, and each of the branched beams is on the rotation axis. It is characterized by irradiating the same point with different directions.

(4) The radiotherapy apparatus according to the present invention, for example, on the premise of the configuration of (1), is provided with an irradiation port rotation mechanism of the electron beam on the radiation beam output side of the electron accelerator microtron,
The irradiation direction of the electron beam to the same point on the rotation axis of the top plate changes according to the rotation of the irradiation port rotation mechanism.

  In addition, this invention is not limited to the above structure, A various change is possible in the range which does not deviate from the technical idea of this invention.

  According to the radiotherapy apparatus configured as described above, the occupied space can be reduced and treatment can be performed without increasing the position of the subject.

  Embodiments of a radiation therapy apparatus according to the present invention will be described below with reference to the drawings.

  Here, prior to describing the overall configuration of the radiotherapy apparatus, a schematic configuration of the electron accelerator microtron 11 provided in the radiotherapy apparatus will be described with reference to FIG.

  FIG. 2 is a schematic plan view of the electron accelerator microtron 11. As shown in FIG. 2, first, an acceleration cavity 61 provided with an electron gun (not shown) in a uniform magnetic field formed by an electromagnet 63 is provided. Is provided. The electron gun generates an electron beam, and the acceleration cavity 61 is supplied with microwaves from the outside to generate an electric field.

  The electron beam output from the electron gun is accelerated by the acceleration cavity 61, travels in a circle around the uniform magnetic field, and returns to the acceleration cavity 61 again. The electrons accelerated again by the accelerating cavity 61 increase in mass due to the principle of relativity, and return to the accelerating cavity 61 while drawing a larger circular orbit within the uniform magnetic field.

  By repeating this, the electron beam accelerated to a predetermined value is extracted to the outside by the extraction pipe 62.

  The extraction pipe 62 is made of a ferromagnetic material, and the internal magnetic flux density through which the electron beam passes is attenuated.

  The electron beam traveling straight in the take-out pipe 62 draws a shifted circular orbit after exiting the take-out pipe 62 and is directed toward the take-out port 64. The electron beam traveling through the extraction port 64 is converged by a quadrupole electromagnet 65.

  In FIG. 6, a 90-degree deflection electromagnet 12 is provided at the tip of the take-out port 64, and the 90-degree deflection electromagnet 12 irradiates an electron beam in a direction perpendicular to the paper surface. Yes.

  The electron accelerator microtron 11 configured as described above is configured to be able to move the take-out pipe 62, whereby the trajectory of the electron beam in a uniform magnetic field can be selected, in other words, the output electron beam You will be able to select energy. For this reason, the selection range of the energy of the extracted electron beam can be widened, and there is little variation in the value of the energy. Therefore, the deflection and convergence of the electron beam by the electromagnet can be facilitated.

<Example 1>
FIG. 1 is a block diagram showing an embodiment of a radiotherapy apparatus including the electron accelerator microtron 11 described above.

  In FIG. 1, the electron accelerator microtron 11 is shown as viewed from the side surface, and is inclined with respect to the floor surface (for example, at 45 °). On the electron accelerator microtron 11, the quadrupole electromagnet 65 and the 90-degree deflecting electromagnet 12 shown in FIG. 2 are drawn.

  The electron accelerator microtron 11 is inclined to the treatment table 14 described later, and the electron beam emitted from the 90-degree deflecting electromagnet 12 is a quadrupole electromagnet 13, a target 21, a cylindrical collimator 22, and A subject lying on the treatment table 14 is irradiated through a radiation detector 23.

  The quadrupole electromagnet 13, the target 21, the cylindrical collimator 22, and the radiation detector 23 are incorporated in the gantry 10 together with the electron accelerator microtron 11.

  The electron beam emitted from the 90-degree deflecting electromagnet 12 is converged by the quadrupole electromagnet 13 and then incident on the target 21. By using a material having a high atomic number and a high melting point, such as gold or tungsten, as the target 21, X-rays generated thereby can be output to the subject, By using an atomic number metal foil, the electron beam can be scattered and spread.

  As shown in FIG. 3 drawn together with the target 21 and the radiation detector 23, the cylindrical collimator 22 has a tapered hole 22a inside and outputs radiation (electron beam, X-ray) for treatment. The irradiation field is limited.

  The radiation detector 23 arranged on the output side of the circular collimator 22 is composed of, for example, a parallel plate ionization chamber, and measures the dose of radiation output for treatment.

  Returning to FIG. 1 again, the treatment table 14 is arranged on the floor surface 20, and the treatment table 14 is a plane parallel to the floor surface around an axis (rotation axis) 15 perpendicular to the floor surface 20. It can be rotated within. That is, the treatment table 14 is fixed to a turntable 14a embedded in the floor, and the turntable 14a can be rotated about the shaft 15 by rotating by a mechanism (not shown). In this case, the treatment table 14 does not interfere with the electron accelerator microtron 11 (more precisely, the gantry 10) during its rotation.

  The electron beam emitted from the electron accelerator microtron 11 through the radiation detector 23 is irradiated so that the beam axis 16 intersects the rotation axis 15.

  The intersection P between the beam axis 16 and the rotation axis 15 is called an isocenter, and the subject is placed on the treatment table 14 with the lesion aligned with the isocenter.

  By irradiating radiation while rotating the treatment table 14 in such a state, the radiation draws a funnel-shaped trajectory with respect to the subject as shown in FIG. Radiation is emitted toward the lesion of the subject. For this reason, it is possible to realize radiation irradiation with an increased concentration of dose in the lesion of the subject.

  The radiotherapy apparatus configured in this manner can reduce the height of the electron accelerator microtron 11 from the floor, and the radiation outlet from the electron accelerator microtron 11 is close to the subject on the treatment table 14. Can be made. For this reason, the occupation space of the radiotherapy apparatus can be reduced, and treatment can be performed without increasing the position of the subject.

  In the embodiment described above, for the sake of simplicity, it is shown that a single cylindrical collimator 22 having a specified hole size is provided.

  However, the cylindrical collimator 22 is configured as, for example, a cylindrical collimator 22A having a rotary exchange mechanism as shown in FIG. 4, and a plurality of circular collimators 22 having different hole sizes depending on the size of the irradiation target. One of them may be selected. That is, in FIG. 4, a cylindrical collimator 22A has a cylindrical collimator having a desired hole diameter by attaching a plurality of cylindrical collimators 22 having different hole diameters to a rotary table 32 and rotating the rotary table 32 by a driving device 31. 22 is configured to be positioned between the target 21 and the radiation detector 23.

<Example 2>
FIG. 5 is a block diagram showing another embodiment of the radiotherapy apparatus according to the present invention and corresponds to FIG. 5, members having the same reference numerals as those in FIG. 1 are members having the same functions.

  In FIG. 5, the configuration different from that of FIG. 1 is that the electron beam emitted from the electron accelerator microtron 11 through the 90-degree deflecting electromagnet 12 passes through the two branch paths, for example. The point is that the point P (isocenter) is irradiated.

  That is, the electron beam from the 90-degree deflecting electromagnet 12 is branched by the branching electromagnet 41, and the electron beam branched to one side passes through the bending electromagnet 42a, the target 21a, the cylindrical collimator 22a, and the radiation detector 23a. The electron beam irradiated to one point P on the rotating shaft 15 and branched to the other is irradiated to the point P through the deflection electromagnet 42b, the target 21b, the cylindrical collimator 22b, and the radiation detector 23b. Yes.

  The radiotherapy apparatus configured in this manner enables irradiation of radiation that draws a double funnel-like trajectory by aligning the lesion of the subject with the isocenter, rotating the treatment table 14, and outputting the radiation. Irradiation with higher concentration of dose can be realized.

<Example 3>
FIG. 6 is a block diagram showing another embodiment of the radiotherapy apparatus according to the present invention and corresponds to FIG. 6, members having the same reference numerals as those in FIG. 1 are members having the same functions.

  In FIG. 6, the configuration different from that of FIG. 1 is different from the electron accelerator microtron 11 in the direction of the electron beam emitted from the 90-degree deflecting electromagnet 12 (shown by the dotted axis 54 in the figure). The irradiation of the isocenter on the rotating shaft 15 is performed at a certain angle θ and is rotated around the dotted axis 54 by the irradiation port rotating mechanism 50.

  The radiotherapy apparatus configured as described above has one radiation irradiation port to the subject, but combines the rotation of the radiation around the dotted axis 54 and the rotation of the treatment table 15 around the rotation axis 15. By irradiating the radiation, it becomes possible to irradiate the lesion of the subject from various directions.

  The irradiation port rotation mechanism 50 is configured as follows, for example. That is, the electron beam emitted in the direction of the dotted axis 54 through the 90-degree deflecting electromagnet 12 is deflected at an angle β by the deflecting electromagnet 55 and further deflected at an angle γ by the deflecting electromagnet 56.

  The radiation emitted through the target 21a, the cylindrical collimator 22a, and the radiation detector 23a is irradiated to the isocenter at an angle θ with respect to the dotted line axis 54.

  The deflection electromagnet 55, the deflection electromagnet 56, the target 21a, the cylindrical collimator 22a, and the radiation detector 23a are mounted on an irradiation port rotary table 51 that is arranged with the dotted line axis 54 as a central axis.

  The irradiation port rotating table 51 is rotated around the dotted line axis 54 by a driving device 53.

  A counterweight 52 is attached to the irradiation port rotary table 51 in order to prevent the center of gravity from decentering during the rotation.

  The electron accelerator microtron 11 shown in each of the above-described embodiments is described as being tilted toward the treatment table 14 and the tilt angle is unchanged. However, you may comprise so that the inclination angle of the electron accelerator microtron 11 can be adjusted using a drive mechanism. By doing so, the effect of adjusting the position of the isocenter on the rotating shaft 15 is achieved.

  Each of the embodiments described above may be used alone or in combination. This is because the effects of the respective embodiments can be achieved independently or synergistically.

It is a block diagram which shows one Example of the radiotherapy apparatus by this invention. It is a schematic plan view which shows one Example of the electron accelerator microtron with which the radiotherapy apparatus by this invention is equipped. It is a figure which shows the detailed structure of the collimator shown in FIG. It is a block diagram which shows the Example of the other collimator replaced with the collimator shown in FIG. It is a block diagram which shows the other Example of the radiotherapy apparatus by this invention. It is a block diagram which shows the other Example of the radiotherapy apparatus by this invention. It is the figure which showed dose distribution in the depth direction of the subject of a radiation beam. It is a figure explaining the dose distribution of the depth direction at the time of irradiating each radiation object facing the subject of a radiation beam. It is a figure explaining a mode that a small-diameter radiation beam is irradiated to a lesion.

Explanation of symbols

11 ... Electron accelerator microtron, 12 ... 90 degree deflection electromagnet, 13 ... Quadrupole electromagnet, 14 ... Treatment table, 15 ... Treatment table rotation axis, 16 ... Radiation beam axis, 21 ... Target, 22 ... Cylindric collimator, 23 ... Radiation detector, 31, 53 ... Drive device, 32 ... Rotary table, 41 ... Branch electromagnet, 42,55,56 ... Deflection electromagnet, 51 ... Irradiation port rotation Table 52 ... Counterweight 61 ... Acceleration cavity 62 ... Take out pipe 65 ... Quadrupole electromagnet

Claims (4)

It has a microtron electron accelerator and a treatment table placed on the floor,
The microtron electron accelerator is disposed with its radiation beam output side inclined to the treatment table side,
The treatment table is configured such that its top plate rotates in a plane parallel to the floor surface without interfering with the microtron electron accelerator,
The radiation therapy apparatus, wherein the radiation beam is irradiated so as to intersect a rotation axis of the top plate.   The radiotherapy apparatus according to claim 1, wherein the radiation beam is irradiated from the microtron electron accelerator by a single beam so as to intersect a rotation axis of the top plate.   2. The beam according to claim 1, wherein the radiation beam is branched into a plurality of beams from the microtron electron accelerator, and each of the branched beams is irradiated to the same point on the rotation axis while changing its direction. Radiotherapy device. An irradiation port rotation mechanism of the electron beam is provided on the radiation beam output side of the microtron electron accelerator,
2. The radiotherapy apparatus according to claim 1, wherein the irradiation direction of the electron beam to the same point on the rotation axis of the top plate changes according to the rotation of the irradiation port rotating mechanism.

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