JP2002191709A - Corpuscular radiation device and its method, and ridge filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the steepness controllability of a dosage distribution at an irradiation region final end section while ensuring the uniformity of an irradiation dosage distribution in the intracorporeal depth direction which is integrated extending to the total irradiation region. SOLUTION: For a three-dimensional irradiation device 10, this ridge filter 11, which regulates the intracorporeal range of a corpuscular beam of a simple energy, and performs the extension/deformation of the range distribution, is provided. The ridge filter 11 has a ridge filter housing apparatus 12, a plurality of ridge filter leaves 13 having different shapes from each other, a ridge filter driving mechanism 14 attached to the ridge filter leaves 13, and a ridge filter controller 15. The ridge filter controller 15 controls the ridge filter driving mechanism 14 conforming to irradiation pattern data which is prepared in advance, and makes the ridge filter leaves 13 advance/retract onto/from the beam axis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for irradiating a particle beam emitted from a particle accelerator, and more particularly to an apparatus and a method for irradiating a particle beam used in a particle therapy apparatus.

[0002]

2. Description of the Related Art In recent years, particle beam therapy using protons and heavy particles has attracted attention as a method for treating cancer, which accounts for about one third of the causes of death in Japan. In this method, by irradiating a cancer cell with a proton beam or a heavy particle beam emitted from an accelerator, it is possible to kill only the cancer cells without substantially affecting normal cells.

[0003] Particle beam therapy methods currently used include:
This is a method called a two-dimensional wobble method or a two-dimensional double scatterer method. In these two-dimensional irradiation methods, the beam diameter of the particle beam is enlarged by a method called a Wobble method or a double scatterer method, and the irradiation area is limited by a collimator, thereby matching the shape of the affected part. However, since the matched beam shape matches the outline of the affected part projected from the beam axis, there is a problem that the irradiation area cannot be precisely matched to the affected part three-dimensionally. Therefore, as a more advanced treatment method of particle beam therapy,
A method of aiming cancer cells with higher accuracy by irradiating the affected part in the body three-dimensionally has been proposed.

One of the three-dimensional irradiation methods is a method called a spot scanning method. In this method, a treatment site is virtually cut into three-dimensional lattice points and irradiation is performed. By performing a three-dimensional irradiation method such as the three-dimensional spot scanning method, it is possible to accurately adjust the beam axis direction to the affected part, and it is possible to expose the affected part to a normal diseased part in comparison with the conventional two-dimensional irradiation method. Can be suppressed.

Hereinafter, a three-dimensional irradiation apparatus for performing cancer treatment by the three-dimensional spot scanning method will be described with reference to the drawings.

FIG. 10 is a schematic configuration diagram showing a three-dimensional irradiation apparatus arranged by a three-dimensional spot scanning method in a treatment room. In the figure, 1 is a treatment bed, 2
Is a three-dimensional irradiation device arranged to irradiate a patient on the treatment bed 1 with a particle beam. 3D irradiation device 2
Is comprised of a scanning magnet 3, a dose monitor 4, a position monitor 5, a ridge filter 6, and a range shifter 7.

Next, the function of each device constituting the three-dimensional irradiation apparatus shown in FIG. 10 will be described. The scanning magnet 3 is
The scanning magnet 3 is moved from the accelerator body (not shown).
Is scanned at a point (X, Y) on a plane perpendicular to the beam axis in the affected part of the body. More specifically, the scanning magnets 3a and 3b are an X-direction scanning magnet that scans the beam in the X direction and a Y-direction scanning magnet that scans the beam in the Y direction, respectively.

[0008] The range shifter 7 controls the position (Z) in the beam axis direction within the affected part in the body. The range shifter 7 is formed of an acrylic plate having a plurality of thicknesses, and the combination of these acrylic plates changes the beam energy passing through the range shifter 7, that is, the range within the body in a stepwise manner. Control of the range within the body in the range shifter 7 is generally switched at regular intervals.

The irradiation dose distribution of a monoenergetic particle beam in the depth direction in the body has a very sharp peak (hereinafter referred to as Bragg peak) distribution near the range of the body as shown in FIG. Using 6,
The range distribution of the monoenergetic particle beam is expanded so as to correspond to the interval of the internal range switched by the range shifter 7.

FIG. 12 shows the shape of the ridge filter 6 for three-dimensional irradiation. The ridge filter shown in FIG. 12 is configured by arranging a plurality of bar pieces made of aluminum. Each bar piece has a substantially isosceles triangular shape, and the thickness in the beam axis direction changes with respect to the vertical direction of the beam.

A dose monitor 4 is provided for measuring a dose to be radiated into the body, and a position monitor 5 is provided for identifying whether a beam position scanned by the scanning magnet 3 is at a correct position.

In the three-dimensional irradiation apparatus shown in FIG.
Three-dimensional irradiation is performed by the following method using each device having the above-described functions. First, the affected part is virtually divided into a plurality of slices with respect to the beam axis, and the incident energy of the particle beam and the acrylic plate thickness in the range shifter 6 are selected according to the position of the deepest slice.

Next, according to the shape of the affected part in the deepest slice, the point n and the position (Xi, Y
i) [i = 1 to n] is selected, and each position (Xi, Yi) is irradiated with a particle beam by the scanning magnet 3. In this case, the energy distribution of the particle beam that has been monoenergetic in the scanning magnet 3 is expanded by the ridge filter 6 so that the in-vivo range distribution corresponds to the slice width. The irradiation dose at the position (Xi, Yi) on this slice is monitored by the dose monitor 4, and when the irradiation of the predetermined dose is detected, the beam is stopped and the scanning magnet 3
The next position (Xi +
1, Yi + 1).

When the irradiation of all points in the slice is completed, the thickness of the acrylic plate in the range shifter 6 is changed, and the next slice irradiation is performed. By repeating such irradiation of points in a slice sequentially for each slice,
Realizes three-dimensional irradiation. As described above, by irradiating the affected part in the body three-dimensionally, it becomes possible to irradiate the diseased part with high accuracy in comparison with the conventional two-dimensional irradiation method.

[0015]

However, the conventional three-dimensional irradiation method such as the three-dimensional spot scanning method has the following problems.

First, in the ridge filter shown in FIG. 12, when the irradiation dose is integrated over all slices,
As shown in FIG. 13, the irradiation dose distribution in the depth direction becomes a jagged distribution having large irregularities. This is because the dose on the shallow side of the body with respect to the Bragg peak is gentle and is affected by slice irradiation on the deeper side. In addition, such a problem is not limited to irradiation by the three-dimensional spot scanning method, but also applies to a method of performing three-dimensional irradiation using a ridge filter, for example, a three-dimensional wobble method or a three-dimensional double scatterer method. This is a problem that arises.

As a method of avoiding such a problem, Barbara Schaffner et al. Have proposed a ridge filter for weighting a Bragg peak in a Gaussian distribution shape (Med. Phys., Vol. 27 (2000), pp. 716). -724). FIG. 14 shows the irradiation dose distribution in the depth direction when this ridge filter is used. As shown in FIG. 14, in this method, since the Bragg peak is enlarged to a gentle Gaussian distribution shape by weighting, the irradiation dose distribution of the jaggedness is flattened, and even if an error occurs in the slice interval, the method is uniform. It has the merit that there is little influence on the performance.

However, this ridge filter weighting method has a serious disadvantage. In other words, because the jagged distribution is gentle, the irradiation dose distribution at the end of the irradiation area becomes poor, and accurate irradiation that matches the shape of the affected part, which is the original purpose of three-dimensional irradiation, cannot be performed. There's a problem.

As described above, in the conventional three-dimensional irradiation method using the ridge filter, uniformity of the irradiation dose distribution in the body depth direction integrated over the entire irradiation region cannot be obtained.
Alternatively, there is a problem that the irradiation dose distribution becomes poor.

The present invention has been proposed in order to solve the above-mentioned problems of the prior art, and its object is to
Improving the steepness controllability of the dose distribution at the end of the irradiation area while ensuring the uniformity of the irradiation dose distribution in the body depth direction integrated over the entire irradiation area, the steepness controllability of the deepest part of the affected area is improved. An object of the present invention is to provide an excellent irradiation device and a method thereof that can realize stable and high-precision irradiation consistent with the shape of an affected part.

[0021]

SUMMARY OF THE INVENTION The present invention has the following features in order to achieve the above object. According to the first aspect of the present invention, there is provided a particle beam irradiation apparatus having a mechanism for controlling energy irradiation of a particle beam, a beam adjustment mechanism for adjusting a range distribution of the particle beam, and irradiation previously created. And a control mechanism for driving the beam adjusting mechanism on the irradiation axis of the particle beam according to the pattern data.

According to a seventh aspect of the present invention, the invention of the first aspect is grasped from the viewpoint of a method. The irradiation region is divided into a plurality of slices, and the slices are controlled while controlling the energy irradiation of the particle beam. In the particle beam irradiation method of sequentially switching and irradiating, the irradiation is performed by switching the method of adjusting the range distribution of the particle beam according to irradiation pattern data created in advance.

According to the first and seventh aspects of the present invention, the method of adjusting the range distribution of the particle beam is appropriately switched according to the irradiation position in accordance with the irradiation pattern data created in advance. By appropriately adjusting the range distribution of the beam, desired irradiation according to the irradiation position can be performed. This makes it possible to improve the steepness controllability of the dose distribution at the end of the irradiation area while ensuring the uniformity of the irradiation dose distribution in the body depth direction integrated over the entire irradiation area. The controllability of the steepness of the part is good, and stable and highly accurate irradiation matched to the shape of the affected part can be realized.

According to a second aspect of the present invention, in the particle beam irradiation apparatus according to the first aspect, the beam adjusting mechanism is a plurality of types of ridge filters different in at least one of a material and a shape. . According to an eighth aspect of the present invention, the invention of the second aspect is grasped from the viewpoint of a method. In the particle beam irradiation method according to the seventh aspect, switching of the adjustment method of the range distribution is performed by changing a material and a material. The method is characterized in that a plurality of types of ridge filters having at least one of different shapes are moved in and out on the beam axis.

According to the second and eighth aspects of the present invention, by selecting the material and shape of the ridge filter, the range distribution of the particle beam can be adjusted with high accuracy, and the structure can be compared. Is simple. When a ridge filter is used, the ridge filter can be moved linearly or planarly on a plane perpendicular to the beam axis, and the drive control of the ridge filter can be realized easily and accurately using existing technology. it can.

According to a third aspect of the present invention, in the particle beam irradiation apparatus according to the second aspect, the plurality of types of ridge filters are arranged so that an irradiation dose distribution in a depth direction of an irradiation target to be irradiated with a particle beam is provided. With respect to a ridge filter for homogenization, the shape of which has been optimized so that the integrated irradiation dose distribution is uniform, and a ridge filter for weighting, which has a shape for weighting a peak near the body range to a Gaussian distribution shape. It is characterized by including.

According to the present invention, for the slice having the largest internal range, the particle beam is adjusted by using the ridge filter for homogenization optimized so as to improve the dose distribution at the end of the irradiation region. Irradiation can be performed so that the range distribution of the beam is adjusted, and other slices are adjusted so as to smoothly adjust the range distribution of the particle beam using a ridge filter for weighting. Thereby, the controllability of the steepness of the dose distribution at the end of the irradiation area can be improved. Further, the flattening of the dose distribution and the uniformity with respect to the error of the slice interval can be ensured by smooth range adjustment other than the slice having the largest range.

According to a fourth aspect of the present invention, in the particle beam irradiation apparatus according to the second or third aspect, the plurality of types of ridge filters correct a range of a passing particle beam. It is characterized by having a layer. According to a twelfth aspect of the present invention, the invention of the fourth aspect is grasped from the viewpoint of a ridge filter, and the ridge filter has a range correction layer for correcting a range of a passing particle beam. It is characterized by.

According to the fourth and twelfth aspects of the present invention, the range change of the particle beam passing through the ridge filter itself and the variation of the range change caused by the manufacturing are corrected by the range of the ridge filter. Since the correction can be made by the layer, it is possible to adjust the particle beam passing through the ridge filter so as to always have a constant range change. Also, the configuration is simpler than when the range correcting means is provided independently.

According to a fifth aspect of the present invention, in the particle beam irradiation apparatus according to any one of the first to fourth aspects, the irradiation pattern data includes a slice when the irradiation area is divided in a depth direction. It is characterized by including the corresponding information. According to a ninth aspect of the present invention, the invention of the fifth aspect is grasped from the viewpoint of a method. In the particle beam irradiation method according to the seventh or eighth aspect, the irradiation pattern data indicates that the irradiation area has a depth of It is characterized by including information corresponding to a slice when divided in the direction.

According to the fifth and ninth aspects of the present invention, by selecting an irradiation pattern for each slice,
Optimal irradiation can be performed for each slice. That is, for the slice with the largest internal range, the range distribution of the particle beam is adjusted so that the steepness controllability of the dose distribution at the end of the irradiation region is improved, and for the other slices, Irradiation can be performed so as to smoothly adjust the range distribution of the particle beam.

According to a sixth aspect of the present invention, in the particle beam irradiation apparatus according to any one of the first to fifth aspects, the irradiation pattern data indicates that a plurality of irradiation positions correspond to the range distribution of the particle beam. Divided into groups of irradiation positions that are the same,
It is characterized in that irradiation is performed by fixing the beam adjustment mechanism at a position corresponding to the adjustment method of each group for each group. The invention according to claim 10 is
The invention of claim 6 is grasped from the viewpoint of a method,
The particle beam irradiation method according to any one of claims 7 to 9, wherein the irradiation pattern data divides a plurality of irradiation positions into irradiation position groups in which a method of adjusting a range distribution of a particle beam is the same. , The irradiation is performed by the adjustment method of each group for each group.

According to the sixth and tenth aspects of the present invention, the number of switching of the adjustment method can be reduced, so that the time required for the switching of the adjustment method is reduced and the treatment time is reduced. it can.

[0034] The invention described in claim 11 is the invention according to claims 7-1.
In the particle beam irradiation method according to any one of the first to third aspects, when the emission energy is controlled by the accelerator body that emits the particle beam, the particles by the range shifter may be used at an energy control interval finer than the energy control interval in the accelerator body. It is characterized by controlling the energy of the line beam. According to the present invention, the range shifter controls the beam energy of the particle beam, that is, the in-vivo range, in a shorter time and with higher accuracy than in the case where only the emission energy is controlled by the accelerator main body of the particle beam. can do.

[0035]

Embodiments of the present invention will be described below with reference to the drawings. Note that the same devices as those shown in the conventional example are shown using the same symbols.

[First Embodiment] [Configuration] FIG. 1 is a schematic configuration diagram showing a three-dimensional irradiation apparatus according to a three-dimensional spot scanning method arranged in a treatment room as a first embodiment. In the figure, a three-dimensional irradiation device 10 arranged to irradiate a particle beam to a patient on a treatment bed 1 includes a scanning magnet 3, a dose monitor 4, a position monitor 5, a ridge filter 11, and a range shifter 7, It is configured.

In the three-dimensional irradiation apparatus 10 shown in FIG. 1, the ridge filter 11 is a beam adjusting mechanism that adjusts the range of a monoenergetic particle beam in the body and expands / deforms the range distribution. The functions of the other devices, that is, the functions of the scanning magnet 3, the dose monitor 4, the position monitor 5, and the range shifter 7 are the same as those described in the above-described conventional example, and thus description thereof will be omitted.

FIG. 2 is a configuration diagram showing the configuration of the ridge filter 11. The ridge filter 11 includes a ridge filter container 12, a plurality of ridge filter leaves 13 (13a, 13b, 13c,...) Having different shapes.
Ridge filter drive mechanism 14 attached to these
(14a, 14b, 14c,...), And a ridge filter controller 15 for controlling these ridge filter driving mechanisms 14. Here, the ridge filter driving mechanism 14 is constituted by an air cylinder, and is controlled by a ridge filter controller 15 to move the ridge filter leaf 13 in and out of the beam axis.

Although three ridge filter leaves 13 are shown in the drawing for simplification, in practice, four or more ridge filter leaves 13 can be used. Conversely, only two ridge filter leaves 13 can be used. In any case, the same number of ridge filter driving mechanisms 14 as the number of ridge filter leaves 13 are provided,
Attached to each ridge filter leaf 13.

FIG. 3 shows the shape of the ridge filter leaf 13 for three-dimensional irradiation used here. The ridge filter leaf 13 shown in FIG. 3 is configured by arranging a plurality of bar pieces made of aluminum. The shape of the ridge filter leaf 13a shown in FIG. 3A is optimized so that the integrated dose distribution is uniform. FIG. 3 (b)
And other ridge filter leaves 13 shown in FIG.
b and 13c have a shape that weights the Bragg peak into a Gaussian shape.

Here, not only the range distribution of the beam passing through the ridge filter but also the range itself is unavoidable, and the variation in the range varies in production. To avoid this, acrylic sheets 16 (16a, 16b, 16c) having different thicknesses are attached to the ridge filter leaves 13 (13a, 13b, 13c), so that the beam passing through the ridge filter 11 always has a constant range change. It has been adjusted to be.

In this embodiment, irradiation pattern data for irradiating the affected part is created in advance, and the ridge filter leaf 13 of the ridge filter 11 is selected according to the irradiation pattern data, and the selected ridge filter leaf 13 is selected. The leaf 13 is driven on the beam axis. FIG. 4 is a data structure diagram showing an example of such irradiation pattern data.

As shown in FIG. 4, the irradiation pattern data includes an irradiation number, a slice ID, a ridge filter ID,
The position (X, Y) and irradiation dose are included. In addition, a beam spot diameter or the like may be included as an irradiation parameter, but is omitted here from the viewpoint of simplifying the description. The following briefly describes these data items.

The irradiation number is a serial number of the irradiation point, and indicates the order of irradiation. The slice ID is obtained when the affected part is virtually divided into a plurality of slices with respect to the beam axis.
It indicates the identification of a slice, and is represented by a serial number in ascending order from the deepest slice. The ridge filter ID identifies a range adjustment pattern by the ridge filter, and is expressed by an ascending serial number corresponding to each ridge filter leaf. Position (X,
(Y) indicates the position of the irradiation point on the slice indicated by the slice ID by X and Y coordinates. The irradiation dose indicates a dose to be irradiated to the three-dimensional grid point specified by the slice ID and the position (X, Y).

In the example of FIG. 4, as described above, since the slice IDs 1, 2,... Are defined in order from the deepest slice, the irradiation by the irradiation pattern data is performed in order from the deepest slice. Will be done.

In the same slice ID, the same ridge filter ID is continuously specified. In this case, in the deepest slice (slice ID: 1), one type of ridge filter leaf 13a (ridge filter ID:
While only 1) is used, the next slice (slice ID: 2) is irradiated using the same ridge filter leaf 13a (ridge filter ID: 1) as the deepest slice, and then another ridge is used. Filter leaf 13b
(Ridge filter ID: 2), indicating that a point on the same slice (slice ID: 2) is irradiated.

[Operation] According to the three-dimensional irradiation apparatus according to the first embodiment as described above, three-dimensional irradiation is performed by the following method using the above-described devices. First,
The acrylic plate thickness in the range shifter 7 is selected according to the slice ID. Subsequently, the ridge filter leaf 13 specified by the ridge filter ID is driven on the beam axis by the corresponding ridge filter drive mechanism 14.

Next, the position (Xi, Xi, 3) on the slice which is a three-dimensional grid point designated by the slice ID and the position (X, Y)
The current value of the scanning magnet 3 is changed so that the beam is irradiated to Yi), and the position (Xi, Y
i) is irradiated with a particle beam. In this case, the distribution of the particle beam having a single energy in the scanning magnet 3 is expanded by the ridge filter 11 in the body. The irradiation dose at the position (Xi, Yi) on this slice is monitored by the dose monitor 4, and when the irradiation of the predetermined dose at that position is detected, the beam is stopped, and the scanning magnet 3 irradiates the next position on the same slice with the same irradiation position. (Xi + 1, Yi + 1).

In this irradiation, the ridge filter ID in the irradiation pattern data at the next irradiation position is set to the current I
When it is different from D, the ridge filter leaf 13 is replaced by the ridge filter controller 15. Further, the slice ID in the irradiation pattern data at the next irradiation position
Is different from the current ID, the acrylic plate thickness in the range shifter 7 is changed. Irradiation is performed three-dimensionally by sequentially repeating irradiation according to the above-described irradiation pattern data.

Next, the dose distribution obtained by the three-dimensional irradiation apparatus according to this embodiment will be described. In the present embodiment, as described above, the shape of the ridge filter leaf 13a used for irradiation of the deepest slice is optimized so that the integrated dose distribution is uniform, and
The ridge filter leaves 13b and 13c used for irradiating the other slices have a shape that weights the Bragg peak into a Gaussian shape. Therefore, the range distribution of the deepest slice is adjusted by the uniforming ridge filter leaf 13a so that the integrated irradiation dose distribution becomes uniform, and the other slices are adjusted by the weighting ridge filter leaves 13b and 13c. , The range distribution is adjusted to weight the Gaussian shape.

FIG. 5 shows, at a certain position (X, Y) at this time, the irradiation dose distribution in the depth direction for each slice and the expanded irradiation dose distribution in the depth direction obtained by integrating them. It is a distribution waveform diagram shown. As is apparent from FIG. 5, the controllability of the steepness of the dose distribution at the end of the irradiation area is improved as compared with the conventional three-dimensional irradiation apparatus. further,
The flattening of the dose distribution and the uniformity with respect to the error of the slice interval are guaranteed by the dose distribution weighted to a Gaussian shape other than the deepest slice.

[Effects] As described above, according to the three-dimensional irradiation apparatus according to the first embodiment, the range distribution of the particle beam is adjusted according to the irradiation position according to the irradiation pattern data created in advance. By appropriately switching the method and appropriately enlarging or deforming the range distribution of the particle beam, desired irradiation according to the irradiation position becomes possible.

In particular, since the irradiation pattern is set for each slice, optimum irradiation can be performed for each slice. That is, for the slice having the largest internal range, the range distribution of the particle beam is adjusted so that the dose distribution at the end of the irradiation region becomes better, and for the other slices, the particle beam is adjusted. Irradiation can be performed so as to smoothly adjust the range distribution.

As a result, while ensuring the uniformity of the irradiation dose distribution in the body depth direction integrated over the entire irradiation area,
Because the steepness controllability of the dose distribution at the end of the irradiation area can be improved, the steepness controllability at the deepest part of the affected part is good, and stable and high-precision irradiation matched to the shape of the affected part can be realized. it can. Therefore, it is possible to realize highly accurate and effective irradiation of the affected part, and to minimize exposure to normal tissues.

Further, by appropriately selecting the shape of the ridge filter, the range distribution of the particle beam can be enlarged or deformed with high accuracy, and the configuration is relatively simple. Linear drive control on a plane orthogonal to the beam axis of the ridge filter can be easily and accurately performed using existing technology such as a cylinder. Further, the change of the range of the particle beam passing through the ridge filter itself and the variation of the range change caused by the manufacturing are controlled by an acrylic sheet (range correction layer) 16 attached to the ridge filter leaf 13.
Can be adjusted so that the particle beam passing through the ridge filter 11 always has a constant range change. Also, the configuration is simpler than when the range correcting means is provided independently.

A plurality of irradiation positions are divided into groups of irradiation positions using the same ridge filter leaf 13 by the same method of adjusting the range distribution of the particle beam, and the same ridge filter leaf 13 is passed through each group. Since the irradiation is performed by the irradiation, the number of times of switching the adjustment method can be reduced, so that the time required for switching the adjustment method can be reduced and the treatment time can be reduced. Hereinafter, this advantage will be described.

First, as a mechanical problem, it takes a longer time to drive the ridge filter than to scan the irradiation position using an electromagnet. For example, when the ridge filter is moved in and out of the beam axis by an air cylinder, 1
A drive time of about seconds is required. Therefore, if the ridge filter is frequently driven to switch the adjustment method, the dead time related to irradiation increases, the treatment time is prolonged, and a physical burden is imposed on the patient.

On the other hand, in the present embodiment, the irradiation positions using the same adjustment method are divided into groups, and the ridge filter is not required to be driven in each group. Since the time can be reduced as much as possible, there is a great advantage that an extra physical burden is not applied to the patient.

[Modifications] In the first embodiment, as an example, an irradiation example using a plurality of types of ridge filter leaves, that is, a ridge filter leaf 13a for equalization and ridge filter leaves 13b and 13c for weighting. Although shown, the more types of ridge filter leaves used, the more adjustment methods can be selected as the range distribution adjustment method. Also, by using more ridge filter leaves, it is possible to further enhance the uniformity of the expanded irradiation dose distribution.

In the first embodiment, an example in which a plurality of ridge filter leaves 13 are driven by individual air cylinders (ridge filter driving mechanism 14) has been described. However, a specific method for driving the ridge filter is described. The configuration is
Any selection can be made as long as the effectiveness of the present invention is not impaired. For example, it is conceivable to drive the ridge filter leaf by an electromagnetic motor. Also, a plurality of ridge filter leaves and ridge filter elements are fixed on a disk or an XY drive stage, and a ridge filter inserted on a beam axis by rotating the disk or operating the XY drive stage on a plane. It is also possible to change the leaf and ridge filter elements.

FIG. 6 is a configuration diagram showing a modification of the driving configuration of such a ridge filter. In the modification shown in FIG. 6, a plurality of ridge filter leaves 13 (13a, 13a,
13b, 13c,. . ) Instead of driving them individually
One ridge filter 21 is replaced with a plurality of ridge filter elements 23 (23a, 23b, 23c,
.. . ), And these ridge filter elements 23 are integrally driven by an XY drive stage 24. The XY drive stage 24 is controlled by a ridge filter controller 25.

The plurality of ridge filter elements 23 (2
3a, 23b, 23c,. . ) Include an acrylic sheet 26 (26a, 26b, 2) having a thickness adjusted for each element.
6c,. . ) Is attached so that the variation in the range of the beam passing through each element is adjusted. Further, the plurality of ridge filter elements 23 are manufactured so as to have a certain size and the same shape, and the irradiation pattern data is obtained by grouping the irradiation positions passing through the same ridge filter element among the irradiation positions. It is created so that the number of times of driving the filter is reduced.

When the range of the particle beam is adjusted by using the ridge filter 21 of FIG. 6 as described above, the XY drive stage 24 is controlled by the ridge filter controller 25 to operate the ridge filter 21. Then, the ridge filter element 23 is switched. That is, when the ridge filter controller 25 receives the irradiation position (X, Y) and the ridge filter ID specified by the irradiation pattern data, the ridge filter controller 25 sets the specified irradiation position (X, Y).
The XY drive stage 24 is driven such that the ridge filter element (for example, 23c) corresponding to the ridge filter ID comes above. After the switching, the particle beam is incident on the ridge filter element 23c, so that the range of the particle beam passing through the ridge filter element 23c is adjusted to the shape specified by the ridge filter ID. Even when the ridge filter 21 is used, the same effect as when the ridge filter 11 shown in FIG. 2 is used can be obtained.

[Second Embodiment] [Configuration] FIG. 7 schematically shows a three-dimensional irradiation apparatus according to a second embodiment, which is disposed in a treatment room by a three-dimensional expanded beam method, particularly a three-dimensional wobble method. It is a block diagram. Here, an example in which the present invention is applied to the three-dimensional wobble method is shown. However, the three-dimensional scatterer method is basically the same except for the beam expansion method, and the other parts have the same configuration.

In the figure, a three-dimensional irradiation device 30 arranged to irradiate a patient on the treatment bed 1 with a particle beam is provided with a scatterer 37, a wobble magnet 38, a dose monitor 4,
Position monitor 5, ridge filter 11, range shifter 7,
And a multi-leaf collimator 39. The three-dimensional irradiation apparatus 30 according to the present embodiment having such a configuration includes:
In the three-dimensional irradiation apparatus 10 of the first embodiment described above, a wobble magnet 38 is arranged instead of the scanning magnet 3, a scatterer 37 is arranged on the incident side of the wobble magnet 38, and a scatterer 37 is arranged on the emission side of the range shifter 7. The multi-leaf collimator 39 is arranged. The other parts are configured exactly the same as in the first embodiment. The ridge filter 11 has the configuration shown in FIG. 2, and the ridge filter leaf 13 has the shape shown in FIG. Have.

The scatterer 37, the wobble magnet 38, and the multi-leaf collimator 39 in the three-dimensional irradiation device 30 shown in FIG.
The function of is described below. The scatterer 37 functions to enlarge the beam width of the spot beam incident on the scatterer by a scattering phenomenon inside the scatterer.

The wobble magnet 38 scans the beam expanded by the scatterer 37 at a point (X, Y) on a plane perpendicular to the beam axis in the affected part of the body. More specifically, the wobble magnets 38a and 38b are an X-direction wobble magnet that scans a beam in the X-direction and a Y-direction wobble magnet that scans in the Y-direction.

In the X-direction wobbler magnet 38a and the Y-direction wobbler magnet 38b, the value of the current flowing therethrough fluctuates according to the sine function at the same frequency.
And the phase of the current of the Y-direction wobbler magnet 38b is maintained in a state shifted by 90 degrees. For example, if these frequencies are both 3
In the case of 1 Hz, the beam emitted from the wobble magnet has a frequency of 31 Hz because the phase of the current is shifted by 90 degrees.
Is a beam that rotates in a circle. The beam shape obtained by integrating this over one second, for example, becomes a shape enlarged in a disc shape with respect to the center of the beam axis.

Although the beam expanded by the scatterer 37 is scanned by the wobbler magnet 38 here, the order is changed, and the spot beam scanned by the wobbler magnet 38 is expanded by the scatterer 37. A beam of similar shape is obtained.

The multi-leaf collimator 39 is composed of a plurality of iron plates, and restricts the beam expanded into a disc shape into an arbitrary shape by the positions where these iron plates are inserted from both sides of the beam axis. Things. Multileaf collimator 39
The multi-leaf collimator is deformed so that the shape of the beam passing through it conforms to the shape of the affected area of the patient. The deformation of the multi-leaf collimator is performed for each acrylic plate thickness of the range shifter 7, that is, for each in-vivo range, and the irradiation area is adjusted to the shape of the affected part.

The functions of the other devices, ie, the scanning magnet 3, the dose monitor 4, the position monitor 5, the ridge filter 11, and the range shifter 7 are the same as those described in the conventional example or the first embodiment. Therefore, the description is omitted here.

FIG. 8 is a data structure diagram showing an example of irradiation pattern data used in the present embodiment. As shown in FIG. 8, the irradiation pattern data includes an irradiation number, a slice ID, a ridge filter ID, a multi-leaf collimator shape ID (MLCID), and an irradiation dose. That is, instead of “position (X, Y)” in the first embodiment, “multi-leaf collimator shape ID”
(MLCID). "

This multi-leaf collimator shape ID (MLCI
D) shows a method of shaping the beam in accordance with the shape of the affected part with respect to the irradiation of the slice indicated by the slice ID, and is represented by serial numbers in ascending order. Others
The scatterer material, thickness, wobble electromagnet current value, and the like may be included as irradiation parameters, but are omitted here from the viewpoint of simplifying the description.

[Operation] According to the three-dimensional irradiation apparatus according to the second embodiment described above, three-dimensional irradiation is performed by the following method using each of the above-described devices. First,
The point that the acrylic plate thickness in the range shifter 7 is selected according to the slice ID and the point that the ridge filter leaf 13 specified by the ridge filter ID is driven on the beam axis by the corresponding ridge filter driving mechanism 14 are as follows. This is similar to the first embodiment.

In this embodiment, each leaf of the multi-leaf collimator 39 is driven in accordance with the multi-leaf collimator shape ID, and thereafter, irradiation of a particle beam is performed. In this case, the particle beam that was a spot beam at the time of incidence is expanded by the scatterer 37 and the wobble magnet 38 to become an expanded beam, and the beam shape is shaped by the multi-leaf collimator 39. In addition, the ridge filter 31 expands the in-vivo range distribution of the particle beam having a single energy at the time of incidence.

The irradiation dose on this slice is measured by the dose monitor 4
When the irradiation of the predetermined dose in this slice is detected, the beam is stopped, the range shifter 7, the ridge filter 11, and the multi-leaf collimator 39 are changed according to the irradiation pattern data, and the irradiation target is changed to the next slice. . Irradiation is performed three-dimensionally by sequentially repeating irradiation according to the above-described irradiation pattern data.

[Effect] The dose distribution obtained by the three-dimensional irradiation apparatus according to the second embodiment as described above is the same as the dose distribution shown in the first embodiment. That is, according to the present embodiment using the same ridge filter 11 as in the first embodiment, the same effect as in the first embodiment can be obtained.

[Modification] In the second embodiment, as in the first embodiment, the ridge filter 11 shown in FIG.
Has been described, but the ridge filter and the drive configuration thereof according to the second embodiment include various drive configurations including the ridge filter drive configuration shown in FIG. 6 as in the ridge filter according to the first embodiment. Can be obtained, and similarly excellent effects can be obtained. Various modifications of the ridge filter are the same as those described in the first embodiment, and a description thereof will not be repeated.

[Third Embodiment] [Configuration] FIG. 9 is a schematic configuration diagram showing a three-dimensional irradiation apparatus for a three-dimensional spot scanning method as a third embodiment. The three-dimensional irradiation apparatus 40 according to the present embodiment is configured to perform energy control at a finer control interval by the range shifter 47 when the accelerator main body has a mechanism for controlling energy.

In this case, the basic configuration of the three-dimensional irradiation device 40 is the same as that of the above-described first embodiment, but in this embodiment, the thickness of the acrylic plate of the range shifter 47 is limited. . That is, the range shifter 47 used in the present embodiment is formed of an acrylic plate having a thickness of at most 2 cm. An acrylic plate having a thickness of 0.25 mm is used as one of the elements of the range shifter 47.

[Operation and Effect] According to the present embodiment, using the three-dimensional irradiation device 40 having the above-described configuration,
Rough energy setting can be performed by the accelerator main body, and fine adjustment can be performed by the range shifter 47. for that reason,
The in-vivo range of the particle beam can be controlled in a shorter time and with higher accuracy without substantially affecting the beam diameter. This will be described below.

First, in general, the advantage of switching the energy of the accelerator body is that the beam diameter can be changed to an arbitrary size for each energy by adjusting the setting of the focusing electromagnet. Further, by switching the energy of the accelerator body, it is considered that there is an advantage that it is not necessary to use a range shifter for energy switching, and it is possible to prevent the beam diameter from becoming large due to scattering by the range shifter itself.

However, it takes a longer time to change the energy in the accelerator main body than to change the energy in the range shifter. That is, when energy is controlled by the accelerator main body, a parameter for setting a plurality of electromagnets and the like constituting the accelerator is held as a table in the accelerator control device, and this parameter is used to change the energy value. , It takes a significant time for the energy to actually change after issuing the parameter replacement command. This significant time is much longer than the time required to change the energy with the range shifter.

On the other hand, in the present embodiment, only rough energy setting is performed in the accelerator main body, and fine adjustment is performed by the range shifter 47. The internal range can be controlled in a shorter time.

The range shifter 4 used in this embodiment
7 is made of an acrylic plate having a thickness of at most 2 cm or less, so that the influence on the beam diameter can be reduced. In particular, by using an acrylic plate having a thickness of 0.25 mm as one of the elements of the range shifter 47,
Generally, the range can be controlled with higher precision than when controlling the energy of the accelerator body.

The dose distribution obtained by the three-dimensional irradiation apparatus according to the third embodiment as described above is similar to the dose distribution shown in the first embodiment. That is, according to the present embodiment using the same ridge filter 11 as in the first embodiment, the same effect as in the first embodiment can be obtained.

[Modification] As a method of describing irradiation pattern data in an irradiation apparatus applied to an accelerator body having an energy control function as in the third embodiment, the pattern data itself includes the accelerator emission energy and the range shifter ID. And a method in which only the energy is described in the pattern data and the control mechanism calculates the accelerator emission energy and the range shifter ID. Regardless of the method used, the effect obtained is the same. Further, in the third embodiment, as in the first embodiment, the case where the ridge filter 11 shown in FIG. 2 is used has been described. However, the ridge filter and the driving configuration thereof in the third embodiment are the same as those of the first embodiment. Similar to the ridge filter of the embodiment, various modifications are possible, including the drive configuration of the ridge filter as shown in FIG. 6, and similarly excellent effects can be obtained.

[Other Embodiments] The present invention is not limited to the above embodiments, and various other modifications can be made within the scope of the present invention.

For example, in the first and third embodiments, the three-dimensional irradiation apparatus using the three-dimensional spot scanning method has been described, and in the second embodiment, the three-dimensional irradiation apparatus using the Wobble method has been described. The feature relating to the adjustment of the range distribution is applicable to a three-dimensional irradiation apparatus by the double scattering method and a three-dimensional irradiation apparatus by other methods as well, and similarly excellent effects can be obtained.

Further, in the third embodiment, the three-dimensional irradiation apparatus using the three-dimensional spot scanning method in which the accelerator body has an energy control function has been described.
2 by both the accelerator body and the range shifter according to the present invention
The feature relating to the step energy control can be similarly applied to a three-dimensional irradiation device using a three-dimensional wobble method or a double scattering method, and the same effect can be obtained.

Further, in each of the first to third embodiments, the case where the irradiation position is changed by moving the beam axis has been described, but the present invention fixes the patient to the beam axis. The present invention is similarly applicable to a case where a treatment bed or a treatment chair is driven. Even in this case, in exactly the same manner, by using a plurality of types of ridge filter leaves, the steepness controllability of the deepest part of the affected part is good, and stable and high-precision irradiation matched to the shape of the affected part is realized. be able to.

[0092]

As described above, according to the irradiation apparatus and the irradiation method of the present invention, the uniformity of the irradiation dose distribution in the body depth direction integrated over the entire irradiation area is improved, and the irradiation dose distribution is improved. By improving the sharpness, steepness controllability at the deepest part of the affected part is good, and stable and highly accurate irradiation matched to the shape of the affected part can be realized.

Therefore, by using the irradiation apparatus and the irradiation method of the present invention, it is possible to realize highly accurate and effective irradiation to the affected part and to minimize the exposure to normal tissues.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a three-dimensional irradiation apparatus using a three-dimensional spot scanning method according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a configuration of a ridge filter used in the three-dimensional irradiation apparatus of FIG. 1;

FIG. 3 is a sectional view showing each shape of a plurality of ridge filter leaves in the ridge filter of FIG. 2;

FIG. 4 is a data structure diagram showing an example of irradiation pattern data used in the three-dimensional irradiation apparatus of FIG.

5 is a distribution waveform diagram showing an irradiation dose distribution in a depth direction in each slice irradiation by the three-dimensional irradiation apparatus of FIG. 1 and an irradiation dose distribution in a depth direction integrated for all slice irradiations.

6A and 6B are diagrams showing a modification of the ridge filter used in the three-dimensional irradiation apparatus of FIG. 1, wherein FIG. 6A is a configuration diagram showing a ridge filter and a driving configuration thereof, and FIG. -A
Line sectional view.

FIG. 7 is a schematic configuration diagram showing a three-dimensional irradiation apparatus using a three-dimensional wobble method according to a second embodiment of the present invention.

FIG. 8 is a data structure diagram showing an example of irradiation pattern data used in the three-dimensional irradiation apparatus of FIG.

FIG. 9 is a schematic configuration diagram showing a three-dimensional irradiation apparatus using a three-dimensional spot scanning method according to a third embodiment of the present invention.

FIG. 10 is a schematic configuration diagram showing a three-dimensional irradiation apparatus using a three-dimensional spot scanning method in a conventional example.

FIG. 11 is a distribution waveform diagram showing an irradiation dose distribution in a depth direction of a single energy particle beam.

FIG. 12 is a sectional view showing a shape of a ridge filter in the three-dimensional irradiation apparatus in FIG. 10;

FIG. 13 is a distribution waveform diagram showing an irradiation dose distribution in a depth direction integrated for irradiation of all slices by the three-dimensional irradiation device of FIG.

FIG. 14 is a distribution waveform diagram showing a dose distribution in the depth direction obtained by integrating irradiation of all slices when a single energy particle beam is shaped in a Gaussian shape.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Treatment bed 2,10,30,40 ... Three-dimensional irradiation device 3 ... Scanning magnet 4 ... Dose monitor 5 ... Position monitor 6,11,21 ... Ridge filter 7,47 ... Range shifter 12 ... Ridge filter storage device 13 ... Ridge Filter leaf 14 ... Ridge filter driving device 15 ... Ridge filter controller 16 ... Range adjustment plate 23 ... Ridge filter element 24 ... XY drive stage 25 ... Ridge filter controller 26 ... Range adjustment plate 37 ... Scattering body 38 ... Wobble magnet 39… Multi-leaf collimator

Claims (12)

[Claims] 1. A particle beam irradiation apparatus having a mechanism for controlling energy irradiation of a particle beam, comprising: a beam adjustment mechanism for adjusting a range distribution of the particle beam; A particle beam irradiation apparatus, comprising: a control mechanism for driving the beam adjustment mechanism on a particle beam irradiation axis. 2. The particle beam irradiation apparatus according to claim 1, wherein the beam adjusting mechanism is a plurality of types of ridge filters different in at least one of a material and a shape. 3. A shape of the plurality of types of ridge filters is optimized such that an integrated dose distribution is uniform with respect to a dose distribution in a depth direction of an irradiation target to be irradiated with a particle beam. A ridge filter for homogenization,
3. The particle beam irradiation apparatus according to claim 2, further comprising a weighting ridge filter having a shape for weighting a peak near a body range into a Gaussian distribution shape. 4. The particle beam irradiation apparatus according to claim 2, wherein the plurality of types of ridge filters have a range correction layer for correcting a range of a passing particle beam. 5. The particle beam irradiation according to claim 1, wherein the irradiation pattern data includes information corresponding to a slice when the irradiation area is divided in a depth direction. apparatus. 6. The irradiation pattern data divides a plurality of irradiation positions into groups of irradiation positions in which the adjustment method of the range distribution of the particle beam is the same, and assigns each group a position corresponding to the adjustment method of each group. The particle beam irradiation apparatus according to claim 1, wherein the irradiation is performed with the beam adjustment mechanism fixed. 7. A particle beam irradiation method for dividing an irradiation region into a plurality of slices and sequentially switching the slices while controlling energy irradiation of the particle beam to perform irradiation, wherein particles are irradiated in accordance with irradiation pattern data created in advance. A particle beam irradiation method characterized in that irradiation is performed by switching a method of adjusting a range distribution of a line beam. 8. The method according to claim 1, wherein the range distribution adjustment method is switched.
The particle beam irradiation method according to claim 7, wherein the irradiation is performed by moving a plurality of ridge filters on and off the beam axis. 9. The particle beam irradiation method according to claim 7, wherein the irradiation pattern data includes information corresponding to a slice when the irradiation area is divided in a depth direction. 10. The irradiation pattern data is such that a plurality of irradiation positions are divided into irradiation position groups in which the adjustment method of the range distribution of the particle beam is the same, and irradiation is performed for each group by the adjustment method of each group. The particle beam irradiation method according to any one of claims 7 to 9, wherein: 11. When controlling the emission energy with an accelerator body that emits a particle beam, energy control of the particle beam by a range shifter is performed at an energy control interval finer than the energy control interval of the accelerator body. The particle beam irradiation method according to any one of claims 7 to 10. 12. A ridge filter having a range correction layer for correcting the range of a passing particle beam.