JP2001161840A - Radiation treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation treatment apparatus in which the length of a direction of radiation beam axis and the cross-sectional area of a surface perpendicular to the beam axis of a snout can be sufficiently suppressed in a drawn-in state of the snout. SOLUTION: In this apparatus, a snout 50 for connecting an irradiation field forming device to an irradiation head 4 is constituted two stages of a cylindrical structure consisting of a cylinder part 52 as a first moving member and a disc member 54 as a second moving member to miniaturize the snout 50 and to prevent radiation from leaking. By thus constituting, the structure of the snout made to be compact and an irradiation field with high performance can be formed, resulting in execution of a treatment with high degree of freedom and accuracy, and cost for forming a treatment system can be reduced. Furthermore, the radiation can be prevented from leaking and a patient or devices in a rotary gantry may be protected from undesired exposure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation therapy system using high-energy radiation, and more particularly to a radiation treatment system using a rotating gantry to irradiate radiation from an arbitrary position around a diseased part of a patient. To a radiotherapy device.

[0002]

2. Description of the Related Art One type of large-sized radiotherapy apparatus using a particle accelerator such as a synchrotron as a radiation source is, for example, a radiotherapy using a rotating gantry and an irradiation field forming apparatus described in JP-A-10-234874. There is a system.

The radiation therapy system will now be described. As shown in FIG. 5, this system uses a rotating gantry 18 to irradiate the treatment bed 7 which is held horizontally and around the center thereof. The field forming device 3 is configured to be rotatable so that radiation therapy can be performed on a patient laid on the treatment bed 7.

Here, first, as shown in the figure, the rotating gantry 18 is a general term for a radiation irradiation chamber for rotating the irradiation field forming device 3 around a patient, and is rotated about a rotating gantry axis. It is a large cylindrical device made to be able to do.

[0005] The irradiation field forming apparatus 3 is a generic name of an apparatus for forming the characteristics of radiation incident along the irradiation beam axis 9 from a particle accelerator (not shown) according to the affected part of the patient. A snout 5 and an irradiation head 4 are provided at the end of a main body in which devices necessary for forming are built.

An irradiation head (also referred to as a treatment head) 4 includes a patient bolus 1 for adjusting a radiation irradiation cross-sectional shape at a depth position of an affected area in accordance therewith, and a patient collimator 2 for finally determining an irradiation contour at the affected area. Is installed,
This is attached to the irradiation field forming device 3 by a snout 5.

[0007] The snout 5 moves the irradiation head 4 back and forth along the irradiation beam line 9, and intersects the rotation axis of the rotating gantry 18 with the irradiation beam beam 9, that is, between the isocenter 8 and the irradiation head 4. In the related art, for example, as shown in FIGS. 3 and 4, a cylindrical guide portion 10A or guide portion 10B is used, and thereby the snout 5 is irradiated with the irradiation beam 9a. A method of guiding the robot so that it can be moved along was adopted.

In general, a linearly movable actuator such as a ball screw is used to drive the snout 5. Here, first, in the example of FIG.
As shown in the figure, a cylindrical guide portion 10A is provided inside the irradiation field forming device 3 so that when the snout 5 is retracted, it enters the inside of the irradiation field forming device 3 along the guide portion 10A. It was done.

Next, in the example of FIG. 4, a cylindrical guide portion 10B extending to the outside of the irradiation field forming device 3 along the irradiation line beam line 9 is used.
Even if it extends outside B and retracts, it does not enter the inside of the irradiation field forming device 3.

When a patient is treated using the radiotherapy apparatus shown in FIG. 5, radiation is generally applied to the affected part in the following procedure to carry out the treatment. By a predetermined diagnostic device, the position of the affected part in the patient's body,
The size and the like are identified, and a diagnosis result is given.

The diagnosis result is sent to a predetermined treatment planning device via an information network or an image network, so that the treatment plan in which the irradiation direction, irradiation field, dose distribution, etc. of the diseased part is determined, matches the shape of the diseased part peculiar to the patient. Processing data required to obtain the patient bolus 1 and the patient collimator 2 is created and determined.

The determined processing data is sent to a predetermined preparation device via a network, and a patient bolus 1 and a patient collimator 2 are prepared by machining. Retract snout 5 into the irradiation apparatus 3, a state in which distance is taken largely between the tip and the isocenter 8 of the irradiation head 4, i.e. laying the patient by a maximum distance D _MAX in the treatment bed 7.

Using a predetermined patient positioning device such as a laser marker or X-ray CT, the patient is positioned so as not to move. The patient bolus 1 and the patient collimator 2 are mounted on the irradiation head 4. The rotating gantry 18 is rotated to move the irradiation head 4 of the irradiation field forming device 3 toward the treatment position.

With the snout 5 pulled out of the irradiation field forming apparatus 3, the irradiation head 4 is brought as close as possible to the patient, and the irradiation head 4 is brought closer to the isocenter 8 to a minimum distance _DW within a range where the irradiation head 4 does not come into contact with the patient. In response to a doctor's instruction, an irradiation start signal is given from the irradiation control device to the radiation acceleration control device so that high-energy radiation is supplied to the irradiation field forming device 3.

As a result, the patient is irradiated with high-energy radiation from the irradiation head 4 via the patient bolus 1 and the patient collimator 2, and at this time, a Bragg peak of the radiation is formed in the affected area, so that an effective treatment is performed. Is obtained.

Here, the Bragg peak is a position where the radiation dose becomes maximum at a certain depth from the surface of the patient's body as disclosed in, for example, Japanese Patent Application Laid-Open No. 11-47291. is there.

[0017]

The prior art described above does not take into consideration that a space longer than the moving distance of the snout is required at the installation portion of the guide portion of the snout.
There has been a problem that the area of the snout in a cross section perpendicular to the radiation beam axis direction increases, and the length of the irradiation field forming apparatus along the radiation beam axis direction increases.

The problem of the prior art will be described with reference to FIG. 5. In such a radiotherapy apparatus, the radiation incident on the irradiation field forming apparatus 3 from the particle accelerator is:
It is formed so as to have a scattering angle, that is, to obtain a large irradiation field.

However, at this time, since the radiation is also scattered by the equipment in the irradiation field forming device 3 and the patient collimator 2 installed in the irradiation head 4, unnecessary radiation to other than the affected part is avoided. In order to perform an accurate treatment, it is necessary to minimize the distance between the irradiation head 4 and the isocenter 8 during the treatment, that is, to bring the irradiation head 4 as close as possible to the affected part.

Conversely, when the patient is laid on the treatment bed 7 and positioned with respect to the isocenter 8, or when the rotating gantry 18 is rotated by 360 degrees, the distance between the irradiation head 4 and the isocenter 8 is minimized. It needs to be large.

When a radiotherapy apparatus is used for actual medical treatment, the frequency of use is considered to be about once every 15 minutes. Therefore, the distance between the irradiation head 4 and the isocenter 8 can be quickly and precisely adjusted. Therefore, it is common to use a drive mechanism having an electric drive mechanism and a position detection function using an encoder.

On the other hand, in the irradiation field forming apparatus 3, it is necessary to shorten the length in the beam axis 9 direction in order to reduce radiation attenuation and unnecessary scattering. If the rotation gantry 18 can be shortened, the radius of rotation of the rotating gantry 18 can be reduced, and inertia associated with rotation can be reduced, so that the cost of the driving device and the control device of the rotating gantry 18 can be reduced, and The construction cost can be reduced by reducing the size of the building.

Furthermore, since the rotating gantry 18 needs to be rotated around the patient who is lying down so that the treatment affected part coincides with the isocenter 8, the area of the cross section perpendicular to the radiation beam axis 6 of the snout 5 is increased. Is large, interference between the snout 5 and the patient or the treatment bed 7 causes the rotating gantry 1
The drive range such as the position 8 and the treatment bed position is limited, and the treatment range is limited.

More specifically, in the case described above, the maximum distance D _MAX between the tip of the irradiation head 4 and the isocenter 8 does not exceed a large value. In order to secure a large space around the tip of the irradiation head 4 and the isocenter in a state where the snout 5 is retracted, as shown in FIG. It is necessary to have a cantilever structure in which only the root of 4 is held. For this reason, the snout 5 needs to be guided by a mechanism that has a minimal possibility of bending in structure.

On the other hand, in the above case, it is necessary to properly fix the irradiation head 4 at a predetermined position with the snout 5 extended to near the maximum stroke.
In addition, at this time, in order to obtain high treatment accuracy, even if the rotation angle of the rotating gantry 18 is changed, it is necessary that the center axis of the irradiation head 4 and the radiation beam axis 9 always coincide without deviation. No.

Therefore, in the prior art, a length longer than the driving distance of the snout is required in the irradiation field forming apparatus as the installation portion of the guide portion, and in the example of FIG. It is necessary to increase the cross-sectional area,
In addition, when the irradiation head 4 is brought closer to the isocenter 8, a space 11 is formed between the irradiation head 4 and the irradiation field forming device 3, so that there is a problem that radiation scattered from the space may leak to the outside. Would.

[0027] On the other hand, in the example of FIG. 4, on the body of the irradiation apparatus 3 moves away considerably farther than the maximum distance D _MAX from isocenter 8, snout 5 or longer, the problem to hold the positioning accuracy and strength Will occur.

Further, in these prior arts, the guide 1
At 0A and 10B, a length longer than the moving stroke of the snout 5 is required. When a ball screw is used for driving the snout, a long ball screw is required.

An object of the present invention is to provide a radiation therapy apparatus in which the length of the snout in the retracted state in the direction of the radiation beam axis and the cross-sectional area of a plane perpendicular to the beam axis of the snout can be sufficiently suppressed. is there.

[0030]

SUMMARY OF THE INVENTION An object of the present invention is to provide a rotating gantry, which moves an irradiation field forming device around an affected part of a patient, and which is attached to the irradiation field forming device via a snout. In a radiation treatment apparatus of a type that performs treatment by irradiating radiation from a head, the snout is:
This is achieved by a moving mechanism including a plurality of moving members that linearly move in conjunction with the same direction.

At this time, the above-mentioned object is achieved even if the moving member comprises a plurality of coaxial cylindrical members, and these cylindrical members are nested. In this case, the positioning of the moving mechanism is performed. However, the above object can be achieved even if the elastic member is provided by the elasticity of the elastic body and the tension of the wire balanced with the elastic body.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a radiotherapy apparatus according to the present invention will be described in detail with reference to the illustrated embodiments.
FIG. 1 is an enlarged side sectional view showing an irradiation field forming apparatus and a snort portion according to the first embodiment of the present invention. One embodiment in which the present invention is applied to the radiotherapy apparatus shown in FIG. FIG. 7A shows a state in which the snout is completely retracted, and FIG. 7B shows a state in which the snout is extended to the full stroke limit.

In FIGS. 1 (a) and 1 (b), reference numeral 50 denotes the entire snort, which is a double cylindrical member 51, 52, a first disk member 53, and a second disk member 52. Disk member 5
4, first and second guide members 55 and 56, first and second springs 57 and 58, wire 59, pulleys 60 and 61,
In addition, a wire winding actuator 62 is provided.

Here, the patient porous body 1, the patient collimator 2, the irradiation field forming device 3, and the irradiation head 4 are as described with reference to FIG. The device is a device necessary for the above-mentioned irradiation field formation.

The outer cylindrical member 51 has a lower end portion.
It is made of a cylindrical member having a flange on the inner peripheral surface (lower side in FIG. 1) and having both ends open, and is attached to the lower end of the irradiation field forming device 3 as shown in the figure. It is. In addition, at least three cylindrical first guide members 55 are attached downward.

The inner cylindrical member 52 constitutes a first moving member, and has a flange on the inner peripheral surface at the lower end thereof.
The upper end (upper side in FIG. 1) is made of a cylindrical member having a first disk member 53, and a hole provided in the periphery of the disk member 53 is formed in the guide member 55 as shown in the figure. By being inserted, it is held in the first cylindrical member 51 so as to be able to move up and down in the drawing, and at least three cylindrical second guide members 56 are provided therein toward the lower side. ,
Installed.

The second disk member 54 constitutes a second moving member, and is made of a member provided with at least three holes in the periphery of the disk, and these holes are inserted into the guide member 56. As a result, the irradiation head 4 is held in the cylindrical member 52 in such a manner that it can move up and down in the figure, and the irradiation head 4 is attached to the lower surface thereof.

Therefore, the irradiation head 4 and the inner cylindrical member 52 are nested with respect to the outer cylindrical member 51, and the disk members 53,
By sliding the hole 54, the snout retracted state shown in FIG. 1 (a) can be changed from the snout retracted state shown in FIG. 1 (b) to the snout retracted state shown in FIG. It will be configured.

Next, the first and second springs 57, 58
Are made of coil springs each having a predetermined spring constant, the first spring 57 is on the guide member 55 so as to be above the disc member 53, and the second spring 58 is on the disc member 54. Each is inserted into the guide member 56 so as to be on the upper side.

The springs 57, 58
Has a dimension longer than the entire movable range (full stroke) of the disk members 53 and 54 by the guide members 55 and 56, respectively, in a free state where no compressive force is applied,
Even when the snout is pulled out as shown in FIG. 1B, a predetermined repulsive force remains.

Next, the wire 59 is a flexible rope having a predetermined tensile strength, and one end of the wire 59 is connected to the second disk member 5.
4 is connected to a predetermined member on the upper side, and the pulleys 60, 6
1 leads to the wire winding actuator 62,
The other end is connected to the winding portion of the actuator 62. Here, the actuator 62 is a kind of electric hoist equipped with a wire winding drum (winding drum), and is configured so that the winding amount of the wire 59 can be controlled with high accuracy.

Therefore, when the snout is pulled out as shown in FIG.
9, the second disk member 54 is pulled upward, so that the second disk member 54 and the cylindrical member 52 are respectively moved upward against the elasticity of the springs 57 and 58, Eventually, the snort retracted state shown in FIG.

Conversely, when the snort retracted state shown in FIG.
If the wire 9 is rewound, the wire 59 is loosened, so that the second disk member 54 and the cylindrical member 52 are respectively moved downward by the repulsive force of the springs 57 and 58, and finally, as shown in FIG. The snout draw-out state shown can be achieved.

As a result, by adjusting the winding length of the wire 59 by the actuator 62, any position between the snout retracted state shown in FIG. 1A and the snout extended state shown in FIG. The irradiation head 4 can be moved to the position, and can be positioned there.

After the position is determined in this manner, the force for holding the irradiation head 4 at this position appears on the wire 59 in balance with the elastic force of the springs 57 and 58 and the elastic force. The strength of the force is determined by the spring constants of the springs 57 and 58 and the actuator 62.
Can be arbitrarily determined by selecting the ability of the wire 59 to hold the wire 59.

As a result, according to the embodiment of FIG. 1, each moving member of the snout 50, that is, the irradiation head 4 attached to the second disk member 54 and the cylindrical member 52 inside are located outside. Since the cylindrical member 51 is nested, the second disk member 5 is compared with the maximum distance D _MAX that can be set between the tip of the irradiation head 4 and the isocenter 8.
The moving distance of the cylindrical member 52 between the fourth and the fourth is small.

Therefore, according to this embodiment, the length of the radiation beam axis 9 can be sufficiently shortened without providing the guide member of the snout 5 so as to enter the inside of the irradiation field forming apparatus 3. As a result, the cross-sectional area of the irradiation field forming apparatus 3 can be reduced, and the irradiation field forming apparatus 3
Can be sufficiently close to the isocenter 8, so that the positioning accuracy and strength can be maintained with a margin.

At this time, by using a material having a high radiation shielding effect, such as copper, a copper alloy, lead, or a lead alloy, as the material of the cylindrical members 51 and 52, leakage of radiation from the side portions can be prevented, It can be provided with a function as a mold collimator or a tool for narrowing the irradiation range of radiation.

FIG. 2 is an enlarged side sectional view showing an irradiation field forming apparatus and a snort portion according to a second embodiment of the present invention. The present invention is applied to the radiation therapy apparatus shown in FIG. FIG. 1A shows an embodiment in which the snout is completely retracted, and FIG. 2B shows a state in which the snout is fully drawn out. Is the same.

The difference between the embodiment of FIG. 2 and the embodiment of FIG. 1 is that the cylindrical member 5 serving as the first moving member is provided.
2 is outside the cylindrical member 51, and the second moving member is
The second embodiment is changed from the second disk member 54 to the second cylindrical member 63 in this embodiment, and is configured to be further outside the cylindrical member 52.

Then, the cylindrical member 5 serving as the first moving member
A flange portion 64 extending to the outer peripheral side is formed at the upper end of 2, and a flange portion 65 extending to the outer peripheral side is also formed at the upper end of the second cylindrical member 63 serving as the second moving member.
Another difference is that at least three holes provided in these flange portions 64 and 65 are inserted into and guided by the respective guide members 55 and 56.

The irradiation head 4 is attached to the lower end of the outermost second cylindrical member 63, and as a result,
Each of the cylindrical members 5
1 is the thinnest, and thereafter, from the cylindrical member 52 to the cylindrical member 6
It is 3 thick.

As a result, each guide member 55, 56
Are also provided outside the cylindrical members 51 and 52. Thus, each spring 57, 58, wire 59, pulley 6
0, 61 and the actuator 62 are the same as in the embodiment of FIG.

According to the embodiment shown in FIG. 2, the cross-sectional area on the irradiation head 4 side can be made larger than the cross-sectional area on a plane perpendicular to the radiation beam axis 9 on the irradiation field forming apparatus 3 side. By applying the present invention to a large radiation therapy apparatus, there is obtained an advantage that an effective therapy result can be expected.

At this time, the cylindrical members 51 and 52 and the cylindrical member 63 are made of a material having a high radiation shielding effect, such as copper, copper alloy, lead, and lead alloy, so that the cylindrical members 51 and 52 can be viewed from the side. This can prevent the leakage of radiation, and can have a function as a cylindrical collimator or a doubles for narrowing the irradiation range of radiation.

By the way, in the above embodiment, the first
The spring constant of the second spring 58 may be different from that of the second spring 58. For example, if the spring constant of the spring 57 on the first moving member side is made smaller than the spring constant of the spring 58 on the second moving member side, as shown in FIGS. 1 (a) and 2 (a). When the wire 57 is rewound by the actuator 62 from a certain retracted state and the tension is relaxed, only the irradiation head 4 attached to the disk member 53 or the cylindrical member 63 as the second moving member is initially pulled out, and thereafter, The operation that the cylindrical member 52, which is the first moving member, is pulled out together with the irradiation head 4 is obtained. On the contrary, the wire is pulled out from the snout drawn state shown in FIGS. 1B and 2B. When the tension is applied by winding the 57, it is possible to obtain an operation in which the cylindrical member 52 is first retracted together with the irradiation head 4 and then the irradiation head 4 is retracted.

A similar operation can be obtained by providing an independent wire and an actuator for each moving member. For example, the moving member is pulled out in ascending order of the cross-sectional area of a plane perpendicular to the beam axis at the tip end. can do.

In the above embodiment, the case where the number of stages of the moving member of the snout 50 is two has been described. However, in the present invention, the number of stages can be increased to three or four. Although the cross-sectional area of the plane perpendicular to the radiation beam axis in the snort retracted state increases, the length in the radiation beam axis direction can be further reduced.

Therefore, according to the above-described embodiment, since the snout is a cylindrical multi-stage type, shielding in the direction perpendicular to the snout radiation beam can be obtained while the irradiation head 4 is close to the isocenter 8, and There is an effect that unnecessary exposure is not given to devices in the rotating gantry.

[0060]

According to the present invention, since the length of the radiation beam in the axial direction in the retracted state of the snout can be shortened, radiation attenuation and unnecessary scattering can be suppressed, and the treatment can be performed efficiently. is there.

Further, the length of the irradiation field forming apparatus itself can be shortened since the length in the beam axis direction when the snout is retracted can be shortened. As a result, the radius of rotation of the rotating gantry can be reduced. There is an effect that the cost required for the driving device and the control device of the rotating gantry can be reduced, and the building cost can be reduced by reducing the size of the building where the rotating gantry is installed.

Further, since the cross-sectional area of the plane perpendicular to the radiation beam axis of the snout can be reduced, interference with the patient and the bed can be reduced, and the degree of freedom of the treatment range such as the position of the rotating gantry and the bed can be increased. And highly accurate treatment can be performed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part for describing an embodiment of a radiotherapy apparatus according to the present invention.

FIG. 2 is a sectional view of a main part for explaining another embodiment of the radiation therapy apparatus according to the present invention.

FIG. 3 is a cross-sectional view of a main part for describing an example of a conventional radiotherapy apparatus.

FIG. 4 is a cross-sectional view of a main part for explaining an example of a conventional radiotherapy apparatus.

FIG. 5 is an overall configuration diagram showing an example of a radiotherapy apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Patient bolus 2 Patient collimator 3 Irradiation field forming device 4 Irradiation head 5, 50 Snout 6 Distance between irradiation head and isocenter 7 Treatment bed 8 Isocenter 9 Radiation beam axis 10A, 10B Guide part 11 Space 18 Rotating gantry 51, 52 Cylindrical member 53 1st disk member 54 2nd disk member 55 1st guide member 56 2nd guide member 57 1st spring 58 2nd spring 59 wire 60, 61 pulley 62 actuator for wire winding 63 Second cylindrical member 64 First flange portion 65 Second flange portion

Continuing from the front page (72) Inventor Hiroyuki Watanabe 3-1-1 Sachimachi, Hitachi-shi, Ibaraki F-term in the Nuclear Power Division of Hitachi, Ltd. 4C082 AA01 AC04 AE01 AG26 AJ01 AJ08 AP16

Claims (3)

[Claims] 1. An irradiation field forming apparatus is moved around a diseased part of a patient using a rotating gantry, and radiation is irradiated from an irradiation head attached to the irradiation field forming apparatus via a snout. The radiotherapy apparatus according to claim 1, wherein the snout is constituted by a moving mechanism including a plurality of moving members that move linearly in the same direction. 2. The invention according to claim 1, wherein the moving member comprises a plurality of coaxial cylindrical members,
A radiotherapy apparatus characterized in that these cylindrical members are nested. 3. The radiotherapy apparatus according to claim 1, wherein the positioning of the moving mechanism is given by the elasticity of the elastic body and the tension of the wire balanced with the elasticity.