JP4077121B2 - Variable compensator and radiation irradiation device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a variable compensator and a radiation irradiation apparatus. More specifically, the present invention relates to a radiation irradiation apparatus represented by particle beams such as proton beams and X-rays, and a variable compensator used in the radiation irradiation apparatus.
[0002]
[Prior art]
FIG. 8 represents a proton therapy device described in the medical physics magazine published by Kanai et al. In FIG. 7, 151 is a proton beam, 152a and 152b are scatterers for increasing the beam size by scattering the beam, 153 is a beam intensity monitor, 154 is a water column that uniformly attenuates the energy of the proton beam, 155 is a multi-leaf collimator that limits the beam width, and 156 is a compensator called a bolus that attenuates energy according to the shape of the tumor in the human body, and is made of a material such as acrylic that provides energy attenuation similar to water. Reference numeral 157 denotes a computer connected to the beam intensity monitor 153, the water column 154, and the multi-leaf collimator 155. Reference numeral 158 denotes a human body, and 159 denotes a tumor inside the human body. Reference numeral 160 denotes an organ vulnerable to radiation such as a spinal cord located behind the tumor.
[0003]
In such a proton beam therapy apparatus, since the bolus 156 has the surface shape of the deepest position of the irradiation target such as the tumor 159, irradiation can be performed without giving a dose to the spinal cord immediately behind the tumor 159. As a result, the organ 160 such as the spinal cord can be protected.
[0004]
[Problems to be solved by the invention]
In the conventional proton beam therapy apparatus, if a bolus is not used, a high dose is given to normal tissues behind the tumor, which may cause side effects. However, since the bolus is different for each tumor shape, it has to be prepared for each patient and further for each direction of irradiation to the patient, and therefore, it is necessary to exchange at the time of treatment. Therefore, treatment using many irradiation directions is not efficient, and it is difficult to perform essential multi-directional irradiation in a short time in order not to give side effects to normal tissues.
[0005]
The present invention has been made to solve such problems, and an object thereof is to provide a variable compensator using a fluid instead of a bolus that is troublesome to manufacture and replace, and a radiation irradiation apparatus using the same. And It is another object of the present invention to provide a variable compensator and a radiation irradiation apparatus that can facilitate multi-directional irradiation that does not require bolus preparation and replacement in a treatment system using a rotating gantry.
[0006]
[Means for Solving the Problems]
In the variable compensator according to claim 1 of the present invention, an elastic membrane and an elastic member are respectively provided in a partitioned portion of a container arranged symmetrically with respect to a partition wall in a container framed to hold the whole. Membrane deformation means is provided, and the elastic membrane is deformed by the elastic membrane deformation means in an antisymmetric manner at the partitioned portion .
[0007]
According to a second aspect of the present invention, there is provided a variable compensator comprising a plurality of yarns in which the elastic membrane deformation means is connected to the elastic membrane.
[0008]
According to a third aspect of the present invention, there is provided a variable compensator comprising tension variable means for adjusting the tension of the plurality of yarns.
[0009]
According to a fourth aspect of the present invention, the variable compensator includes a fluid in the lower container of the elastic membrane and a gas in the upper container.
[0010]
In the variable compensator according to claim 5 of the present invention, silicone fluid is used as the fluid.
[0011]
The variable compensator according to claim 6 of the present invention uses liquid mercury as the fluid.
[0012]
Furthermore, the variable compensator according to claim 7 of the present invention uses a heavy metal compound solution as the fluid.
[0013]
In addition, the radiation irradiation apparatus according to claim 8 of the present invention includes an elastic membrane on each of the partitioned portions of the container that is symmetrically arranged with respect to the partition wall in the container that is framed to hold the whole. And an elastic membrane deforming means, wherein the elastic membrane deforming means has a variable compensator that deforms the elastic membrane in an inversely symmetrical manner at the partitioned portion . The meaning of inverse symmetry means that the shape of the elastic membrane surface is symmetric with respect to the partition wall and the plane when the elastic membrane surface is flat. For this reason, the total volume of the liquid below the elastic membrane surface of the left and right partition walls is constant regardless of the deformed shape of the elastic membrane surface.
[0014]
According to a ninth aspect of the present invention, the radiation irradiating apparatus comprises a plurality of yarns in which the elastic film deforming means is connected to the elastic film.
[0015]
According to a tenth aspect of the present invention, there is provided a radiation irradiating apparatus comprising tension variable means for adjusting the tension of the plurality of yarns.
[0016]
A radiation irradiation apparatus according to claim 11 of the present invention includes a fluid in the lower container of the elastic membrane and a gas in the upper container.
[0017]
Moreover, the radiation irradiation apparatus concerning Claim 12 of this invention uses a silicone oil as said fluid.
[0018]
Moreover, the radiation irradiation apparatus concerning Claim 13 of this invention uses liquid mercury as said fluid.
[0019]
Furthermore, the radiation irradiation apparatus according to claim 14 of the present invention uses a heavy metal compound solution as the fluid.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a variable compensator and a radiation irradiation apparatus of the present invention will be described with reference to the accompanying drawings.
[0021]
FIG. 1 shows a variable compensator using a fluid according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a frame that holds the whole, for example, an acrylic container, 2 a fluid, for example, a liquid typified by silicone oil, and 3, an elastic membrane, for example, the fluid 2 in the container 1. Synthetic rubber such as ethylene-polyprene rubber that is liquid-tight and radiation resistant, 4 is a strong polyimide-based yarn represented by the trade name Kevlar, and 5 is a joint that joins the yarn 4 and the elastic membrane 3 , 6 is air. In the present embodiment, the plurality of threads 4 connected to the elastic membrane 3 are elastic membrane deformation means. Reference numerals 7a and 7b denote rings for driving the yarn 4. For example, the ring 7a is connected to a motor (not shown). A partition wall 8 for partitioning into two upper and lower chambers is provided inside the container 1, and a projection 10 for smoothing the movement of the yarn 4 is provided in the hole 9 of the partition wall 8. It has been. Further, the entire container is divided into two by the partition wall 11 and is symmetrically arranged, and the proton beam 12 passes through the right half of the container 1. In the present embodiment, the containers 1 are arranged symmetrically by the partition wall 11, but the present invention is not limited to this, and can be arranged symmetrically in two or more pairs. In the structure of FIG. 1, by rotating the motor, the left half elastic film 3 and the right half elastic film 3 always move in reverse symmetry. The driving mechanisms such as the motor and the rings 7a and 7b are all arranged on the left half side of the container 1 so as not to obstruct the passage of the proton beam 12.
[0022]
FIG. 2 shows details of the elastic membrane 3, the thread 4, and the elastic membrane-like connecting portion 5. Reference numeral 30 denotes fixing means for the thread 4 embedded in the elastic film 3, and reference numeral 31 denotes connection means for the thread 4 provided in the short part of the fixing means 30. For example, 30 is made of metal, and is set in a pallet when the elastic film 3 is made of liquid high-temperature synthetic rubber. In this way, the elastic membrane 3 can keep the fixing means 30 for the yarn 4 inside.
[0023]
FIG. 3 shows a state in which a large number of yarns 4 are connected to the elastic membrane 3. However, only a part of the thread 4 is displayed. Actually, yarns are connected to the entire elastic membrane 3 at substantially uniform intervals.
[0024]
FIG. 4 is a view of the variable compensator of FIG. 1 as viewed from above, in which the container 1 and the thread 4 are shown. The right half of the central partition wall 11 is irradiated with a proton beam. In the left half, one ring 7a, 7b for controlling the elastic membrane 3 and one motor 32 for rotating the ring 7a are prepared for each yarn.
[0025]
Next, the operation of the radiation irradiation apparatus in the present embodiment will be described. The length of the bolus in each beam irradiation direction is calculated, the driving length of each yarn is determined based on this length, and a desired bolus shape is formed. Note that FIG. 2 shows the case of irradiation from above. FIG. 5 shows a case where the proton beam 12 is irradiated from another direction, for example, the horizontal direction. Since the gravity of the fluid 2 in contact with the elastic membrane 3 also acts on the elastic membrane 3, even when the position 52 is targeted, the yarn 4 is shifted upward or downward by the gravity action as shown by the position 54. The tension of each thread 4 can be increased by using the tension varying means 50 to reduce the deformation amount of the elastic film 3 due to gravity. In FIG. 5, the tension can be increased by horizontally moving the tension varying means 50 in the left direction F. As shown in FIG. 6, a predetermined value of tension can be applied to each yarn 4 by translating the tension varying means 50 using, for example, a rack 55, a pinion gear 56, and a motor 57. In this way, the deformation amount of the elastic film 3 due to gravity can be reduced even at an arbitrary angle. Practically, this embodiment is simple. Since dose distribution measurement using a water phantom is normally performed before actual patient irradiation, it is possible to check in advance whether or not a correct bolus shape can be configured for each irradiation direction. As a result, if it is found that the desired bolus shape is not obtained, it can be dealt with by further driving the yarn or increasing the tension.
[0026]
By repeating the dose distribution measurement described above, the yarn driving distance and tension for forming various bolus shapes can be made into a database for each irradiation direction. Once the database is created, the driving distance and tension of each yarn for forming a new shape bolus in new irradiation can be easily determined. In this case, the most accurate yarn driving distance and tension can be determined by interpolation. Such calculation processing can be easily realized by using a commercially available neural network program.
[0027]
In this embodiment, a liquid, particularly silicone oil, is used as the fluid. However, if a liquid metal such as mercury or a heavy metal compound solution (for example, bismuth nitrate) is used, the X-ray irradiation intensity can be changed for each irradiation position. It is possible to construct a variable compensator for an X-ray therapy apparatus capable of The variable compensator has a structure that can be retracted in the direction perpendicular to the beam incident axis so that it does not interfere with patient positioning using an X-ray tube or the like. Further, as shown in FIG. 7, the position of the elastic film 3 of the variable compensator is detected by the echo wave of the exploration wave 61 reflected from the elastic film 3 using the ultrasonic sensor group 60 arranged in the container 1. The desired position can also be set. In FIG. 7, it is preferable to arrange ultrasonic sensor groups in the front-rear direction perpendicular to the paper surface.
[0028]
【The invention's effect】
As described above, according to the present invention, multi-directional irradiation can be performed in a short time by using a variable compensator using a fluid instead of a bolus that is troublesome to manufacture and replace. In addition, it is not necessary to cut the bolus with a numerical control machine for each patient, so that it is not necessary to make the bolus and store it after use.
[0029]
Furthermore, in the treatment system using a rotating gantry, the present invention can facilitate multi-directional irradiation in which a bolus is not required to be manufactured and replaced in a short time.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a variable compensator in a radiation irradiation apparatus of the present invention.
FIG. 2 is an enlarged view showing a coupling portion in FIG. 1;
FIG. 3 is an explanatory diagram showing a state in which a large number of systems are connected to the elastic membrane in FIG. 1;
4 is a plan view of the variable compensator in FIG. 1. FIG.
FIG. 5 is a diagram illustrating an operation.
FIG. 6 is a perspective view showing an embodiment of a tension varying means.
FIG. 7 is a cross-sectional view showing another embodiment of the variable compensator.
FIG. 8 is a schematic view showing an example of a conventional radiation apparatus.
[Explanation of symbols]
1 container, 2 fluid, 3 elastic membrane, 4 thread, 5 joint, 6 air,
7a, 7b Ring, 8, 11 Partition wall, 9 holes, 10 projections, 12 proton beam, 30 fixing means, 31 connection means, 32, 57 motor, 50 tension variable means, 52, 54 position, 55 rack, 56 pinion Gears, 60 ultrasonic sensors, 61 exploration waves.

Claims (14)

An elastic membrane and elastic membrane deformation means are provided in each of the partitioned portions of the container that are arranged symmetrically with respect to the partition wall in a container that is framed to hold the whole, and the elastic membrane deformation means A variable compensator characterized in that the elastic membrane is deformed in an antisymmetrical manner at the partitioned portion by means.   2. The variable compensator according to claim 1, wherein the elastic film deforming means comprises a plurality of yarns connected to the elastic film.   The variable compensator according to claim 1 or 2, further comprising tension varying means for adjusting tension of the plurality of yarns.   The variable compensator according to claim 1 or 2, wherein a fluid is contained in a lower container of the elastic membrane and a gas is contained in an upper container.   The variable compensator according to claim 4, wherein silicone fluid is used as the fluid.   The variable compensator according to claim 4, wherein liquid mercury is used as the fluid.   The variable compensator according to claim 4, wherein a heavy metal compound solution is used as the fluid. An elastic membrane and elastic membrane deformation means are provided in each of the partitioned portions of the container that are arranged symmetrically with respect to the partition wall in a container that is framed to hold the whole, and the elastic membrane deformation means A radiation irradiating apparatus comprising: a variable compensator that deforms the elastic film in an inversely symmetrical manner at the partitioned portion by means.   9. The radiation irradiating apparatus according to claim 8, wherein the elastic film deforming means comprises a plurality of yarns connected to the elastic film.   The radiation irradiation apparatus according to claim 8 or 9, further comprising tension variable means for adjusting tension of the plurality of yarns.   The radiation irradiation apparatus according to claim 8 or 9, wherein a fluid is contained in a lower container of the elastic membrane and a gas is contained in the upper container.   The radiation irradiation apparatus according to claim 11, wherein silicone fluid is used as the fluid. The radiation irradiation apparatus according to claim 11, wherein the fluid is liquid mercury or easy fusion liquid that is liquid at room temperature .   The radiation irradiation apparatus according to claim 11, wherein a heavy metal compound solution is used as the fluid.

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