JP2526405B2 - Non-uniform ridge filter system for heavy charged particle beam conformal irradiation - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a therapeutic apparatus using a heavy charged particle beam such as a proton beam or a heavy ion beam, and more particularly, a heavy ion beam which concentrates a high dose distribution within a desired range according to the shape of a tumor. The present invention relates to a non-uniform ridge filter system for charged particle beam conformal irradiation.

[0002]

Radiation therapy has been an important part of cancer therapy. As the radiation used for this type of radiation therapy, in addition to the X-rays, gamma-rays, electron beams, etc. that have been used in the past, heavy charged particle beams such as proton beams and heavy ion beams, which have been actively researched recently. There is. The heavy charged particle beam loses energy continuously while destroying a living body like an invisible bullet, and stops at a specific depth determined by the incident energy. The heavy charged particle beam intensively destroys just before stopping. This is because the radiation dose is high just before the charged particle beam stops. This high-dose portion is called a black peak.

On the other hand, since the lesion of the patient to be irradiated has a thickness, in order to uniformly damage the lesion, the heavy charged particle beam must have an energy distribution according to its thickness (width). . A region having a high dose in the thickness direction formed by giving an energy distribution to the heavy charged particle beam is called an expanded black peak.

Conventionally, a ridge filter and a range modulator have been used to give an energy distribution to a heavy charged particle beam to form an expanded black peak.

The ridge filter is a plate having a thickness distribution, and when a heavily charged particle beam passes through it, it has an energy distribution according to the thickness distribution. As such a ridge filter, a heavy charged particle beam is mixed by giving a distribution in the beam direction before entering the ridge filter, or by giving a distribution in the beam direction by a scatterer after passing through the ridge filter. It is possible to eliminate the difference in energy distribution depending on the position.

On the other hand, in the range modulator, a fan-shaped plate having a non-uniform thickness is rotated, and the heavy charged particle beam passing through the range modulator has an energy distribution when averaged over time.

In such a conventional technique, since the energy distribution is uniform regardless of the position of the beam, the width of the expanded black peak is constant regardless of the position. However, the thickness of the lesion depends on its position. Therefore, in the conventional configuration, since a uniform thickness is irradiated regardless of the position, there is a problem that a portion with a thin lesion is irradiated with a high dose even to a portion that is not the lesion.

[0008]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to concentrate a high dose distribution within a desired range according to the shape of a tumor in a therapeutic apparatus using a heavy charged particle beam such as a proton beam or a heavy ion beam. Another object of the present invention is to provide a non-uniform ridge filter system for irradiating heavy charged particle beam conformations.

[0009]

In order to solve the above-mentioned problems and achieve the object, a nonuniform ridge filter system for irradiating a heavy charged particle beam conformation of the present invention comprises: expanded Bragg peak widths and different uneven ridge filter by position, of the heavy charged particle beam to a substantially uniform dose of high dose region of non-uniform thickness comprised lesion Therefore patients heterogeneous ridge filter A multi-leaf collimator that opens and closes according to the amount of irradiation of the beam is provided.

Further, in order to solve the above-mentioned problems and to achieve the object, the nonuniform ridge filter system for irradiation of a charged particle beam conformation of the present invention is a treatment apparatus using a charged particle beam, and is enlarged in black depending on the position. a heterogeneous ridge filter peak widths are different, the heavy charged particle beam to a substantially uniform dose of high dose region of non-uniform thickness comprised lesion Therefore patients heterogeneous ridge filter <br/> A multi-leaf collimator that opens and closes according to the amount of irradiation of the beam is provided.

The non-uniform ridge filter has a wide range.
In order to form a non-uniform characteristic over the range, the expansion block
Multiple combinations of polygonal filters with uneven rack peak width
It is preferable to be configured .

Further, the non-uniform ridge filter is formed in advance in order to form non-uniform characteristics over a wide range.
The enlarged black peak width is unevenly distributed in the created circular hole.
It is preferable that a plurality of single circular filters are combined and fitted .

Further, the nonuniform ridge filter is preferably one in which the expanded black peak width changes substantially continuously.

[0014]

According to the present invention, by adopting the configuration described above so the following effects. That is, the ridge filter for obtaining the expanded black peak as described above has a different structure depending on the position (location), the width of the expanded black peak is changed depending on the irradiation position, and the patient is irradiated in the region of high dose distribution matching the lesion. To do. Note that changing the width of the enlarged black peak, is irradiated at a higher than thicker regions doses thin region expansion <br/> large black peaks when a direction perpendicular to the beam intensity in the traveling direction of the beam is uniform . Synchronous to the beam dose, that is,
The dose can be made substantially uniform by using a multi-leaf collimator that opens and closes depending on the small size, or by using non-uniform beam scanning. Therefore, according to the present invention, it is possible to concentrate a high dose distribution within a desired range according to the shape of the tumor.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the heterogeneous ridge filter system for irradiation of a charged particle beam conformation of the present invention will be described below with reference to the drawings. First, an example of a treatment apparatus using a heavy charged particle beam such as a proton beam or a heavy ion beam to which the system of the present invention is preferably applied will be described with reference to FIGS. 1 to 3.

In FIG. 1, the proton beam accelerator 10 and the energy beam transport system 16 in the beam transport system 12 constituting the present treatment apparatus are shown in detail in FIGS. 1 and 2. FIG. 2 is a view of the beam transport system 12 of FIG. 1 viewed from the II-II direction. The proton accelerator 10 is composed of a hexagonal synchrotron and has a high-frequency accelerator 14. The hexagonal synchrotron makes it easier to design a high-performance strong focusing type as compared with, for example, a quadrangular synchrotron, and allows the extraction of various beams by increasing the number of straight portions.
The beam transport system 12 includes a vertical upward beam transport system 18, a vertical downward beam transport system 20, and a horizontal beam transport system 28.
Is provided.

In order to reach a deep lesion and perform treatment, a proton having a required beam intensity must be accelerated to a required energy. For example, to reach a depth of 32 cm in the body, a proton requires 230 MeV of energy. The procedure in this example for accelerating protons to such energy will be described below.

First, negative hydrogen ions are generated from an ion source of hydrogen molecules, and the generated negative hydrogen ions are electrostatically charged at 50 ke.
It accelerates to V and enters the injector 22 for pre-acceleration. As the injector 22, a tandem electrostatic accelerator having a terminal voltage of 2.5 MV is used. The use of a tandem electrostatic accelerator has the advantage that the energy width can be reduced. Negative hydrogen ions are accelerated to 2.5 MeV, converted into protons by the carbon thin film at the terminal, and accelerated to 5 MeV. The protons are guided to the proton accelerator (main accelerator) 10 by the medium energy beam transport system 16.

The main accelerator 10 is a strongly focused synchrotron with a super period of 6, and its main parameters are shown in Table 1. The proton orbits about orbit of about 35 m, and is accelerated every time it passes through the high-frequency accelerating unit, and reaches 230 MeV after about 0.5 seconds. The protons that have reached the required energy are extracted from the synchrotron 10 and guided to the treatment room by the beam transport system 12.

The energy of the proton beam must correspond to the depth of the lesion. Although the synchrotron 10 can take out any energy during acceleration, the first step is to reduce the proton beam energy to 12 in consideration of the certainty and speed of energy switching.
There are three levels of 0 MeV, 180 MeV, and 230 MeV. After this is achieved, extraction with arbitrary energy is performed.

In general, achieving the design energy by the synchrotron 10 has been ensured by the current technology, but the target of the beam intensity is 20 nanoamperes (nA).
To achieve this, careful consideration at the design stage and careful adjustment after completion are required. Most of the beam loss occurs at the time of incidence on the synchrotron 10, at the start of acceleration in the synchrotron 10, and at the time of extraction of protons from the synchrotron 10. Since the beam intensity of the injector 22 is not so high, the beam intensity of the synchrotron 10 is secured by injecting protons to the synchrotron 10 a large number of times.

If a linear accelerator of 8 MeV or more for injecting negative hydrogen ions is used as the injector 22, the conversion of the negative hydrogen ions into protons by the carbon thin film can be used to control the beam intensity with high efficiency. A proton can be injected into the synchrotron 10.

The beam loss at the start of acceleration is dealt with by preparing a trajectory correction magnet in advance and adjusting the synchrotron 10 including these magnets. Beam loss on extraction from the synchrotron 10 results in increased residual activity,
It needs the most attention. The beam extraction method can be selected from slow extraction by high integer resonance with high extraction efficiency and fast extraction by a kicker with a fast rise. Therefore, it is possible to form an irradiation field by beam scanning due to the slow extraction.

Fast beam extraction efficiency is theoretically 100%
It becomes possible to measure the arrival position of the proton beam in the body by ultrasonic waves, start proton acceleration in synchronization with the movement of the lesion organ, or store a pre-accelerated proton beam in the synchrotron 10, By extracting the proton beam in synchronism with the movement of the focal organ, it is possible to perform irradiation with a reduced exposure dose to normal tissue.

The acceleration of the proton beam by the accelerator is performed by a monitor ionization chamber (reference numeral 8 in FIG. 3) provided in the irradiation controller.
The signal from 6) is used. Both the proton beam by slow extraction and the proton beam by fast extraction are extracted to the same beam transport system 12. Of the two treatment rooms, the first treatment room 24 has a vertical vertical beam transport system 18, 20 and a horizontal beam transport system 28, and the other second treatment chamber 26 has a vertical vertical beam transport system 18, 20 and a proton beam. The beam is supplied. The selection of the vertical up / down direction and the horizontal direction depends on the distribution electromagnet 30.

In the beam transport system 12, electromagnets (for example, reference numerals 62 and 64 in FIG. 1) other than the electromagnets (for example, 90-degree bending electromagnet in FIG. 3) required to guide the proton beam to the required irradiation control device are shown. The power of the electromagnet) is turned off for the purpose of ensuring safety. The conditions of this procedure, along with other general conditions, are incorporated into an interlock system housed in the operation control board (not shown) of the entire system. Accelerator 1
0 and the operating conditions of the beam transport system 12 are set by a computer provided in the operation control panel.

A specific detailed configuration of the irradiation control device 34 is shown in FIG. The irradiation control device 34 shown in the drawing is used in the first treatment room 24.
In the case where three sets of vertical and horizontal irradiation control devices are installed in the above, the detailed configuration of the upper vertical device for controlling the beam from the vertical upward beam transport system 18 is shown. The same structure is applied to the other two sets of beams that control the beam of the vertical downward beam transport system 20 and the beam of the horizontal beam transport system 28. The other two sets are designated by reference numerals 70 and 72.
Indicated by.

The patient 38 is fixed on the central treatment table 36 so that the lesion coincides with the central axis of each irradiation control device.
The position is confirmed by moving the X-ray tube 39 and the image intensifier (II) 40 coaxially.

The irradiation field of the proton beam is formed by scanning the fine-bundle proton beam with the scanning electromagnet 42, enlarging it with the primary scatterer 44, and using the ring stopper 46 at the irradiation position with a substantially uniform intensity of 20 × 20 cm. This is done by forming the above distribution. The divergence of the irradiation field-shaped beam on the surface of the patient is confirmed by the light irradiation field mirror 80.

In the range adjustment in the beam axis direction, the energy fine adjuster 48 attenuates the energy corresponding to the required range in the body, and the ridge filter 50 is selected so that the dose peak width matches the lesion thickness. Expand the width. Further, a bolus 82 is provided to adjust the energy of the proton beam in accordance with the shape of the patient's body surface, the shape of the lesion, and the depth of the nonuniform value lesion in the body. The thickness of the bolus 82 varies depending on each position, and the proton beam energy is absorbed by passing the proton beam through each position.

The shape of the block collimator 52 and the shape of the final collimator 54 are adjusted so as to match the shape of the lesion.

Ridge filter 50 and energy fine adjuster 4
A monitor ionization chamber 90 is installed between the monitor ionization chamber 8 and the monitor 8. This monitor ionization chamber 90 functions as a part of the dose monitoring unit,
When the integrated value of the amount corresponding to the output current exceeds the preset value corresponding to the planned dose, an irradiation stop signal is generated,
Proton irradiation is stopped. These controls are performed by a computer (not shown).

A shutter mechanism 84 and a shielding block 86 are provided to ensure the safety of the treatment room where the proton beam irradiation is not performed.
Is provided.

The arrangement state, conditions, etc. of the respective elements provided in this irradiation device are adjusted depending on the state of the patient 38. This adjustment can be done manually, but
It is preferable to adjust automatically by a computer based on patient data.

According to such an irradiation device, since the three vertical irradiation control devices and the horizontal irradiation control device are fixed, the operation is simple, reliable treatment is possible, and maintenance is easy.

Further, the scanning electromagnet 42 and the primary scatterer 4
4, each element such as the ring stopper 46 is substantially fixedly incorporated in the irradiation device, so that the adjustment is easy,
The device is highly safe and thus accurate treatment is achieved.

The configuration according to FIGS. 1 to 3 described in detail above is a patent application (Japanese Patent Application No. 2-3256) filed by the same applicant.
No. 85), which is a preceding invention by the inventors,
The most preferable feature of the present invention is the apparatus to which the heterogeneous ridge filter system for irradiation of heavily charged particle beam conformations, which concentrates a high dose distribution in a desired range according to the shape of the tumor, is preferably applied.

[0038] Then, the system according to an embodiment of the present invention, as shown in FIGS. 4 to 7, the expanded Bragg peak width is different uneven ridge filter 100 by the position, therefore the patient to the uneven ridge filter 100 synchronization with the irradiation dose of the beam of heavy charged particle beam to a substantially uniform dose of high dose region of non-uniform thickness which is the foci <br/> formation, i.e. the
A multi-leaf collimator 101 that opens and closes according to the amount of the amount is provided.

Further, the system according to another embodiment of the present invention, as shown in FIGS. 4 to 7, expanded Bragg peak width is different uneven ridge filter 100 by the position, therefore the patient to the uneven ridge filter In order to make the dose in the high dose region of non-uniform thickness formed in the lesion of the
According to the smallness, a means for scanning the beam non-uniformly in a direction perpendicular to the traveling direction of the beam is provided. For monitoring the irradiation amount of the beam of the heavy charged particle beam in the above, the monitor chamber shown in FIG. 3 and using the ionization chamber 90 can be used, and the multileaf collimator 101 or the beam scanning can be performed by a computer (not shown). Control means.

The non-uniform ridge filter 100 in the above-described embodiment has a non-uniform characteristic over a wide range.
The expanded black peak width is not uniform.
It is preferable to be configured by combining a plurality of rectangular filters . As the heterogeneous ridge filter 100, wide
Prefabricated to create non-uniform characteristics over a range
A circular hole with a circle with an uneven black peak width
It is preferable that a plurality of shape filters are combined and fitted . Further, the non-uniform ridge filter 100 is preferably one in which the expanded black peak width changes substantially continuously. In this case, the polygon fill
Use either a combination of circular filters or a combination of circular filters
Whether to do it can be appropriately selected according to the size and shape of the lesion.
It

In the system of the present invention, FIGS.
As shown in FIG. 3, the nonuniform ridge filter 100 and the multi-leaf collimator 101 are provided. And these configurations
Results in a substantially uniform energy, which varies depending on the position.
Form a dose distribution of energy that matches the shape of the lesion
It forms a high dose distribution region. Multi-leaf collimator
101 opens and closes according to the amount of beam irradiation,
Make the distribution areas approximately the same. Use multi-leaf collimator 101
Instead, the beam behaves unevenly according to the amount of beam irradiation.
It is also possible to use an electromagnet for scanning the scan.

As shown in FIG. 4 (a), in the absence of the ridge filter, the area of high wave and high dose is narrow. In addition, as shown in FIG. 4B, in the uniform ridge filter 50 that has been used conventionally, a high dose region matching the shape of the lesion is created and irradiated in consideration of the change in the thickness of the lesion. Can not do it. For this reason, irradiation was performed in the high-dose region with the maximum thickness of the lesion regardless of the position. For this reason, an unnecessary high dose is given to normal tissue, which may cause unnecessary radiation damage.

As shown in FIGS. 4 (c) and 5, by using the non-uniform ridge filter 100 and the non-uniform ridge filter 100 and the multi-leaf collimator 101, the shape of the lesion can be substantially matched. It becomes possible to create a high dose distribution region having a uniform dose, and it becomes possible to relatively reduce the dose to unnecessary normal tissue. Therefore, it is possible to irradiate the lesion with a higher dose to improve the treatment result and reduce the radiation damage to the normal tissue.

6 and 7 illustrate the clinical effects of the prior art and the present invention by exemplifying beam irradiation to a patient.
It is. 4 and 5 show that the beam is incident on water.
It shows the dose distribution on the water surface and in the water in the case of being exposed.
As shown in FIGS. 6 and 7, when a dose distribution curve 102 inside the patient 38 is assumed and a lesion 38E is present deep inside the patient 38, regions 38A, 38B, 39C where the dose is gradually increased from the body surface to the deep part. , 38D are formed. In this case, the highest dose is in region 38D,
The lowest is region 38A. As shown in FIG.
When using the single ridge filter 50, the dose is the most
The shape of the high area 38D is larger than the shape of the lesion 38E.
Yes. On the other hand, as shown in FIG. 7, by using the non-uniform ridge filter 100 and the multi-leaf collimator 101, the position, shape and disease of the region 38D having the highest dose can be obtained.
The position and shape of the nest 38E should be almost the same.
Can be.

As described in each of the above embodiments, according to the present invention, it becomes possible to create a high dose distribution region having a substantially uniform dose that conforms to the shape of a lesion, and to a unnecessary normal tissue. The dose can be reduced relatively.
Therefore, it is possible to irradiate the lesion with a higher dose to improve the treatment result and reduce the radiation damage to the normal tissue.

The present invention is not limited to the above-mentioned embodiments, but various modifications can be made without departing from the gist of the present invention.

[0047]

As described above, according to the present invention, the beam
Multi-leaf collimator that opens and closes according to the amount of irradiation or uneven distribution
By using a single beam scan, depending on the tumor shape
Burden to concentrate high dose distribution within desired range
A non-uniform ridge filter system for irradiation of particle beam conformers
Can be provided.

[Brief description of drawings]

FIG. 1 is a plan view of a therapeutic apparatus using a proton beam according to the present invention.

FIG. 2 is a view of the beam transport system downstream of the distribution electromagnet of the apparatus of FIG. 1 as seen from the line II-II.

FIG. 3 is a configuration diagram of a vertically upper portion of an irradiation control device used in the treatment apparatus according to the present invention,

FIG. 4 is a schematic configuration diagram of a heterogeneous ridge filter system for heavy charged particle beam conformation irradiation according to the present invention.

FIG. 5 is a schematic configuration diagram of a heterogeneous ridge filter system for heavy charged particle beam conformation irradiation according to the present invention.

FIG. 6 is a view showing the action of the nonuniform ridge filter system for irradiation of a charged particle beam conformation according to the present invention.

FIG. 7 is a view showing the action of the nonuniform ridge filter system for irradiation of a charged particle beam conformation according to the present invention.

[Explanation of symbols]

100 ... Non-uniform ridge filter system, 101 ... Multi-leaf collimator.

Claims (5)

(57) [Claims] In the treatment apparatus using the method according to claim 1 Heavy charged particle beam, expanded Bragg peak widths and different uneven ridge filter by position, uneven thickness of the high-formed lesion Therefore patients heterogeneous ridge filter A multi-leaf collimator that opens and closes according to the amount of irradiation of the beam of the heavy charged particle beam in order to make the dose in the dose region substantially uniform, Filter system. In the treatment apparatus using the 2. A heavy charged particle beam, expanded Bragg peak widths and different uneven ridge filter by position, uneven thickness of the high-formed lesion Therefore patients heterogeneous ridge filter in a direction perpendicular to the traveling direction of the beam in accordance with the magnitude of the dose of the beam of the heavy charged particle beam to a substantially uniform dose dose range, it and means for non-uniformly scanned the beam A heterogeneous ridge filter system for heavy charged particle beam conformation irradiation. 3. The non-uniform ridge filter is widely used.
In order to form a non-uniform characteristic, the expanded black
A combination of multiple polygon filters with non-uniform peak widths
The heterogeneous ridge filter system for irradiation of a charged particle beam conformation according to claim 1 or 2, which is formed. 4. The non-uniform ridge filter is widely used.
Prefabricated circular shape to create non-uniform characteristics
In the circular hole where the enlarged black peak width is not uniform.
The heterogeneous ridge filter system for irradiation of a charged particle beam conformation according to claim 1 or 2, wherein a plurality of luters are combined and fitted . 5. The heavy charged particle beam conformation irradiating body according to claim 1, wherein the nonuniform ridge filter is such that the expanded black peak width changes substantially continuously. Non-uniform ridge filter system.