JP2003205042A - Radiotherapeutic apparatus and control method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiotherapeutic apparatus which can determine an irradiation position accurately. <P>SOLUTION: A moving mechanism 70 for moving a radiation head 60 is composed of a belt 72, a pulley for movement, a motor and a belt tensioner 72a. The load of the radiation head 60 is distributed over and supported by a guide rail 42. The apparatus is equipped with a rotary encoder 53 for detecting the rotation angle of a frame 40 rotated by a reclining mechanism 50, a sensor head for detecting the moving angle of the radiation head 60 moved by the moving mechanism 70, an optical encoder for detecting the rotation angle of the radiation head 60 rotated by a first swinging mechanism 63, and an optical encoder for detecting the rotation angle of the radiation head 60 rotated by a second swinging mechanism 64. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiotherapy apparatus for irradiating an affected area with radiation in a two-dimensional or three-dimensional manner.

[0002]

2. Description of the Related Art As a method for performing treatment by irradiating a diseased part such as a cancer lesion with radiation, there is stereotactic radiotherapy for intensively irradiating the affected part with radiation. In this stereotactic radiotherapy, the irradiation of normal tissue can be minimized by changing the irradiation direction of the radiation and irradiating the affected area with radiation from multiple directions. Examples of the radiotherapy apparatus for performing this stereotactic radiotherapy include CyberKnife (trademark; Accuray Incorporated (US)), which moves a radiation source to irradiate the affected area intensively, C-arm type electron beam linac, and the like. is there.

The cyber knife is equipped with a small electron beam linac as a radiation source at the tip of an industrial robot arm in which multi-axis joints of about 7 axes are connected in series, and controls the robot arm to define the radiation source. It is a radiotherapy device that is moved to a position and intensively applies radiation to the affected area from this defined position. With the cyber knife, since the robot arm has many degrees of freedom, it is possible to perform irradiation in accordance with the shape of an atypical affected area that is not spherical (has no isocenter). As a result, even for an affected part other than the spherical part, it is possible to kill only the affected part while suppressing damage to normal cells around the affected part due to radiation.

In the C-arm type electron beam linac, a radiation source is mounted on a large arc-shaped frame, and the frame is tilted together with the radiation source, so that the affected area located at the isocenter, which is the center of the arc, is irradiated with radiation. To do.

[0005]

However, the above-mentioned cyber knife and C-arm type electron beam linac have the following problems.
There are the following problems. Since the robot arm of the Cyberknife has a cantilever structure, the robot arm is easily deformed by the load of the electron beam linac. In addition, since the movement of the robot arm is controlled by multiple joints, there is a cumulative position error at each joint. Therefore, there is a possibility that the radiation source may deviate from the specified position, and it seems that there is a problem in accuracy when precise irradiation is required. In addition, since the structure of the robot arm is complicated in the cyber knife, calibration (range measurement) to remove the deviation between the radiation source and the specified position is extremely complicated, and it takes about one week. It is necessary to calibrate. Furthermore, in the cyber knife, since the robot arm has a multi-axis joint and cannot constrain the degree of freedom of the robot arm in a specific direction approaching the patient, the robot arm and the patient can be controlled by a runaway control system that controls the robot arm. It is extremely difficult to arrange a safety device for preventing a collision with the vehicle, and there is a safety problem. Since the C-arm type electron beam linac is a drive system in which a large frame is moved together with the radiation, the displacement of the isocenter and the irradiation point easily occurs due to the deformation of the frame due to the load of the radiation source, but the position of the irradiation point is changed. It has no specific means of correction.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a radiation medical apparatus having excellent irradiation position accuracy.

[0007]

In order to achieve the above object, a radiotherapy apparatus according to a first aspect of the present invention comprises a frame having an arcuate trajectory, and a radiation source movably supported along the trajectory. A moving mechanism for moving the radiation source along the trajectory, wherein the moving mechanism holds a belt connected to the radiation source and the belt arranged along the trajectory. It is characterized by comprising a holding portion, a pulley for feeding the belt along the track, and a motor for rotating the pulley. In this radiotherapy device, a positional error of the radiation source due to the assembly accuracy of the moving mechanism is unlikely to occur, and the radiation source is reliably moved to a predetermined position. Thereby, the radiation can be accurately applied to the center point of the arc.

A radiotherapy apparatus according to a second aspect is a radiotherapy apparatus having a frame having an arcuate trajectory and a radiation source movably supported along the trajectory, wherein the frame is provided with the radiation source. It is characterized in that it is provided with a dispersion supporting portion for distributing and supporting the load. In this radiotherapy apparatus, the load of the radiation source is dispersed and supported by the dispersion supporting unit, so that distortion of the frame due to the load of the radiation source is suppressed. Therefore, the track provided on the frame is always kept in an arc shape. Thereby, the radiation can be accurately applied to the center point of the arc.

A radiation treatment apparatus according to a third aspect is the radiation treatment apparatus according to the second aspect, wherein the dispersion support portion is
It is characterized in that a plurality of guide rails are provided on the frame to form the track. In this radiation device, since the load of the radiation source is dispersed and supported by the plurality of guide rails provided on the frame, distortion of the frame due to the load of the radiation source can be suppressed. Therefore, the guide rail provided on the frame is kept in an arc shape. Also,
Since the radiation source is guided along the guide rail forming the track, the radiation source moves accurately along the track. Thereby, the radiation can be accurately applied to the center point of the arc.

According to a fourth aspect of the radiotherapy apparatus, a frame having an arcuate trajectory, a radiation source movably supported along the trajectory, and a moving mechanism for moving the radiation source along the trajectory. And a tilting mechanism for rotating the frame around a tilt axis so that the orbit describes a spherical surface,
A radiation therapy apparatus comprising: a first swing mechanism that rotates the radiation source about one axis; and a second swing mechanism that rotates the radiation source about another axis different from the one axis. A first angle detector that detects a rotation angle Ψ of the frame, a tilt control unit that controls the tilt mechanism based on the rotation angle Ψ, and a center of the trajectory defined by the trajectory of the radiation source. Second angle detector that detects the movement angle θ of the first neck, a movement control unit that controls the movement mechanism based on the movement angle θ, and the first neck based on the rotation angle Ψ and the movement angle θ. First calculation means for calculating a swing command value for the swing mechanism and a swing command value for the second swing mechanism, respectively, the rotation angle Ψ, the movement angle θ, and the radiation emitted from the radiation source. Second calculating means for respectively calculating a correction command value for the first swing mechanism and a correction command value for the second swing mechanism based on the relationship with the irradiation point, the swing command value and the correction It is characterized by having a swing control section that controls the first swing mechanism and the second swing mechanism based on a command value.

In this radiotherapy apparatus, the rotation angle Ψ of the frame rotated by the tilting mechanism is detected by the first angle detector, and the movement angle θ of the radiation source moved by the moving mechanism is detected by the second angle detector. Since the tilting mechanism and the moving mechanism are controlled based on the detected rotation angle Ψ and moving angle θ, the radiation source is reliably arranged at a predetermined position. Thereby, the reproducibility of the radiation source position can be improved. Further, in this radiotherapy apparatus, the position of the radiation source is determined from the rotation angle Ψ of the frame and the movement angle θ of the radiation source, and the swing command value is calculated based on this position. A swing command value suitable for the position of the radiation source is given. Further, the relationship between the rotation angle Ψ, the movement angle θ, and the irradiation point is obtained by measuring the determined position and the irradiation point of the radiation emitted from this position,
From this relationship, a correction command value that corrects the position error between the irradiation point and the center point of the arc is calculated, and the obtained correction command value is added to the swing command value to correct the position error at the irradiation point of radiation. It This makes it possible to accurately irradiate a desired point with radiation from multiple directions.

A radiation treatment apparatus according to a fifth aspect is the radiation treatment apparatus according to the fourth aspect, wherein the radiation angle rotated by the first swing mechanism is detected as a third rotation angle α.
Angle detector and a fourth angle detector for detecting the rotation angle β of the radiation source rotated by the second swing mechanism, and the swing command value, the correction command value, and the rotation angle α. And the swing control unit is controlled based on the rotation angle β. In this radiotherapy apparatus, the first swing mechanism and the second swing mechanism are based on the rotation angle α detected by the third angle detector and the rotation angle β detected by the fourth angle detector. Is controlled, the swing error of the radiation source is reduced. Further, since the first swing mechanism and the second swing mechanism are controlled also based on the rotation angle Ψ and the movement angle θ, the irradiation direction suitable for the position where the radiation source is arranged can be obtained. Further, by measuring the position represented by the rotation angle Ψ and the movement angle θ and the rotation angle α and the rotation angle β at which the radiation source is rotated at this position, the reproducibility of irradiation can be improved. You can

According to a sixth aspect of the radiotherapy apparatus control method of the present invention, a frame having an arcuate trajectory, a tilting mechanism for rotating the frame around a tilt axis so that the trajectory describes a spherical surface, and a tilting mechanism for the frame. First to detect the rotation angle Ψ
Angle detector, a movement mechanism for moving the radiation source, a second angle detector for detecting a movement angle θ around the center of the trajectory defined by the trajectory of the radiation source, and the radiation source. A first swinging mechanism for rotating the radiation source around one axis, a third angle detector for detecting a rotation angle α of the radiation source rotated by the first swinging mechanism, and the radiation source A second swing mechanism that rotates about another axis different from the axis, and a fourth that detects a rotation angle β of the radiation source rotated by the second swing mechanism.
A method for controlling a radiotherapy apparatus having the angle detector according to claim 1, wherein the first swing is based on a relationship among the rotation angle Ψ, the movement angle θ, and an irradiation point of radiation emitted from the radiation source. A correction command value for the mechanism and the second swing mechanism is calculated, and a swing command value for the first swing mechanism and the second swing mechanism is calculated based on the rotation angle Ψ and the movement angle θ. However, the first swing mechanism and the second swing mechanism are respectively controlled based on the swing command value, the correction command value, the rotation angle α, and the rotation angle β. .

In the method of controlling the radiotherapy apparatus according to the first aspect,
The tilting mechanism and the moving mechanism are respectively controlled based on the rotation angle ψ detected by the angle detector and the moving angle θ detected by the second angle detector, so that the radiation source can be reliably set to the predetermined position. Will be placed in the position. Thereby, the reproducibility of the radiation source position can be improved. Further, since the swing command value is calculated based on the rotation angle Ψ of the frame and the moving angle θ of the radiation source, the swing command value suitable for the position of the radiation source is given to the swing control unit. Further, a correction command value for correcting the deviation between the center point of the circular arc and the irradiation point is calculated from the relationship between the rotation angle Ψ and the movement angle θ and the irradiation point of the radiation, and the correction command value is added to the swing command value. Thus, the error of the radiation irradiation point is corrected. This makes it possible to accurately irradiate a desired point with radiation from multiple directions.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a radiation treatment apparatus and a control method therefor according to the present invention will be described below with reference to FIGS. The radiation treatment apparatus 1 includes a treatment apparatus body 2
And a treatment device controller 3 for controlling the treatment device main body 2
(Shown in FIG. 8). The treatment device body 2 is
As shown in FIG. 1, a bed 3 on which a patient 20 is placed and moved.
0, an arc-shaped frame 40 installed so as to straddle the bed 30 in the width direction, a tilting mechanism 50 for rotating the frame 40, and a radiation head (radiation source including a small electron beam linac installed in the frame 40. ) 60 and a moving mechanism 70 for moving the radiation head 60 in the circumferential direction of the frame 40.

The bed 30 has a bed driving mechanism incorporated therein so that the bed 30 and the bed 3 can move in the longitudinal direction (X-axis direction).
It moves in the 0 width direction (Y-axis direction) and the vertical direction (Z direction). The bed 30 is equipped with a bed position detector (not shown) that detects the position of the bed 30.

The frame 40 has an arc shape and is made of a material such as aluminum which is lightweight and has excellent rigidity. In the present invention, the center point A of the arc formed by the frame 40 is set to the frame 4
It is arranged at a distance of about 90 cm from the inner circumference of 0, but it can be arbitrarily set according to the target treatment form. Side surface 4 facing the vertical direction (Z-axis direction) of the frame 40
An arc-shaped guide rail (track and dispersion support portion) 42 is provided on the la 1a. This guide rail 42
A material with excellent rigidity (for example, SUS)
Material etc.). The center point of the arc formed by the guide rail 42 is provided so as to coincide with the center point A of the arc formed by the frame 40. In the present invention, the guide rail 42 is provided.
The distance from the center of the arc to the center point A is about 1m,
Also regarding this, it can be arbitrarily set according to the target treatment form. As shown in FIG. 3, the guide rail 42 is also provided on the other side surface 41b of the frame 40. A magnetic scale 43 is provided on the inner peripheral surface 41c of the frame 40 along the circumferential direction. Further, the frame 40 is provided with arms 44 so as to face each other with the center point A therebetween. As shown in FIG. 2, the arm 44 extends in the Y-axis direction and then bends in the X-axis direction. At the position where the arm 44 extends in the X-axis direction,
Tilt axes 45a and 45b parallel to the Y axis are provided.
The tilting shafts 45a and 45b are supported by pedestals 46a and 46b installed on both sides of the bed 30, respectively.

The mounts 46a and 46b are provided with tilting mechanisms 50 for rotating the tilting shafts 45a and 45b, respectively. The tilting mechanism 50 includes bearings 51a and 51b that rotatably support the tilting shafts 45a and 45b and a tilting shaft 45a.
The tilting shaft 45a is rotated by a motor 52 and a speed reducer (not shown) that rotate the frame 40 around the tilting shafts 45a and 45b. Tilt axis 45b
Is provided with a rotary encoder (second angle detector) 53 that detects the rotation angle of the frame 40.

The radiation head 60 is attached to the holding frame 62 via a swing shaft (uniaxial line) S provided on both side faces facing the Y-axis direction. This holding frame 6
The emission portion 66 (shown in FIG. 5) of the radiation head 60 attached to the second radiation head 60 is arranged on the axis B connecting the tilt axes 45a and 45b of the frame 40. In the holding frame 62,
First, rotating the radiation head 60 around the swing axis S
A swinging mechanism 63 is provided. The first swing mechanism 63 is a bearing 63 that rotatably supports the swing shaft S.
a, 63b, a motor 63c for rotating the swing shaft S supported by the bearing 63b, and an optical encoder (third angle detector) 6 for detecting the rotation angle of the swing shaft S rotated.
3d. This holding frame 62 has a second
It is attached to the moving mechanism 70 via the swinging mechanism 64.

FIG. 3 is a sectional view of the second swing mechanism 64 and the moving mechanism 70 taken along the line BB in FIG. The second swing mechanism 64 rotates the holding frame 62 around a swing axis T (another axis) parallel to the X axis.
The swing axis T is orthogonal to the swing axis S and is provided so as to pass above the emitting portion 66 of the radiation head.
It is rotatably supported by a bearing (arranged in the speed reducer) 64a of the swing mechanism 64. An optical encoder 64b (fourth angle detector) that detects the rotation angle of the swing shaft T is provided inside the swing shaft T.
A pulley 64c is provided at the end of the swing shaft T. The pulley 64c and the pulley 6 located below the bearing 64a and rotatably attached to the moving mechanism 60.
A belt 64e is stretched between the belt 4e and 4d. The pulley 64d is a motor 64f installed in the moving mechanism 60.
It is connected to the. This motor 64f is a pulley 64d
By rotating the shaft and sending out the belt 64e
To rotate. This causes the radiation head 60 to move around the swing axis T.

The moving mechanism 70 comprises a traveling platform 71 supported by the frame 40 and a belt 72 (shown in FIGS. 1 and 4). The belt 72 is stretched along the upper surface 41d of the frame 40, and both ends thereof are fixed to the frame 40 by belt tensioners (holding portions) 72a. The traveling platform 71 has a U-shaped cross section,
It is installed so as to surround both side surfaces 41a and 41b of the frame and the inner peripheral surface 41c. The second swing mechanism 64 is provided on the side portion 71a of the traveling platform 71 facing the side surface 41a of the frame.
Is attached. A linear guide 73 that engages with a guide rail 42 provided on the side surface 41a of the frame is provided on the side portion 71a. This linear guide 73, as shown in FIG.
Two are provided at intervals in the circumferential direction. In addition, the side portion 7 of the traveling platform 71 facing the side surface 41b of the frame 40.
The 2a is also provided with a linear guide 74 engaged with the guide rail 42 provided on the side surface 41b of the frame 40. The linear guide 74 is formed long in the circumferential direction of the guide rail 42. In this way, by engaging the linear guides 73 and 74 with the guide rail 42,
The load on the traveling table 71, the holding frame 62 attached to the traveling table 71, and the radiation head 60 causes the frame 4 to move.
It is dispersed and supported by guide rails 42 respectively provided on both side surfaces 41a and 41b of 0.

A motor 75 is provided on the side portion 71b of the traveling platform 71.
a is attached. The motor 75a is connected to the rotating shaft 75b. A pulley 75c is provided at the tip of the rotary shaft 75b. This pulley 75c
A drive belt 75d is stretched over the. The driving belt 75d is also stretched over the driving pulley 76 provided on the upper portion of the side portion 71b. The rotating shaft 76a of the drive pulley 76 is supported by a bearing (arranged in the speed reducer) 76b. Further, the end of the rotary shaft 76 a is connected to a moving pulley 77 provided so as to face the driving pulley 76. Therefore, the rotary shaft 7 is driven by the motor 75a.
When 5b is rotated, the drive belt 75c is sent out and the drive pulley 76 is rotated. When the driving pulley 76 rotates, a rotational force is transmitted from the central shaft 76a of the driving pulley 76 to the moving pulley 77, and the moving pulley 77 rotates. As shown in FIG. 4, on both sides of the moving pulley 77, the sending pulley 7 is provided along the circumferential direction of the frame 40.
Four 8 are provided. Belts 72 are alternately laid on the sending pulley 78 and the moving pulley 77, and the sending pulley 78 and the moving pulley 77 rotate so that the belt 72 moves in the circumferential direction of the guide rail 42. Sent to. As a result, the traveling platform 71 connected to the belt 72 moves on the guide rail 42 in the circumferential direction. The bottom portion 7 of the traveling platform 71 facing the inner peripheral surface 41c of the frame 40
A sensor head 79 for reading the magnetic scale 43 is provided at 1c. The sensor head 79 detects the angle formed by the locus of movement of the radiation source 60 along the guide rail 42 and the center point A.

FIG. 5 is a sectional view of the radiation head 60. Reference numeral 65 in the figure denotes a rectangular parallelepiped cover. An electron beam linac 60a is housed in the cover 65. The emission unit 66 of the electron beam linac 60a is
It is provided in the center of the lower surface of the cover 65. This emitting part 6
From 6, an X-ray having an energy of 4 MeV to 10 MeV is emitted in the direction indicated by arrow C in the figure. Reference numeral 67a in the figure is an exhaust pump. This pump 6
7a exhausts the inside of the acceleration pipe 67c via the exhaust pipe 67b. The accelerating tube 67c accelerates an electron beam emitted from an electron gun (not shown) provided above the accelerating tube 67c. The electron beam accelerated by the accelerating tube 67c is
X-rays are generated by colliding with a target 68a provided at the tip of the. This X-ray passes through the primary collimator 68b and is guided to the filter 68c, and the intensity is averaged in the process of passing through the filter 68c. The X-ray that has passed through the filter 68c is a secondary collimator 68.
After the irradiation directions are aligned by d, the dose measuring means 69
The light is emitted from the emitting portion 66 through the light. Dose measuring means 69
At, the dose of X-rays that pass through is measured.

As described above, in the radiotherapy apparatus 1,
The load between the radiation head 60 and the carriage 71 causes the frame 4
The radiation head 6 is supported by the guide rails 42 provided on both side surfaces 41a and 41b of the radiation head 0.
The guide rail 42 and the frame 40 are not distorted by the load of 0 and the traveling platform 71. Therefore, the trajectory of the radiation head 60 is kept in an arc shape. Further, since the radiation head 60 is guided along the guide rail 42 that forms a track, the radiation head 60 moves accurately along the track. Further, since the moving mechanism 70 is composed of the combination of the belt 72, the moving pulley 76, and the motor 75a in which an error due to the assembly accuracy does not easily occur, the radiation head 60 can be reliably moved to a predetermined position.

Next, the operation of the treatment apparatus body 2 will be described. When the moving mechanism 70 is driven, the radiation head 60 moves along with the traveling table 71 in the circumferential direction of the guide rail 42. As a result, the radiation head 60 moves along an arcuate trajectory centered on the center point A. Further, when the tilting mechanism 50 is driven, the frame 40 tilts in the X-axis direction around the tilting shafts 45a and 45b as shown in FIG. As a result, the frame 40 moves on a spherical surface centered on the center point A. Therefore, the frame 40 is tilted by the tilting shaft 45.
The radiation head 6 is rotated while rotating around a and 45b.
By moving 0 in the circumferential direction of the guide rail 42, the radiation head 60 is placed at an arbitrary point on the spherical surface centered on the center point A. By this, the center point A
It is possible to irradiate X-rays from multiple directions.

Further, by driving the first swing mechanism 63,
When the radiation head 60 is rotated around the swing axis S parallel to the Y axis, the irradiation direction of the X-rays emitted from the emitting unit 66 changes, and the irradiation point moves from the center point A in the Y axis direction. Further, when the second swing mechanism 64 is driven to rotate the holding frame 62 together with the radiation head 60 around the swing axis T parallel to the X axis, the irradiation direction of the X-rays emitted from the emitting unit 66 is changed. Change, irradiation point is center point A
To move in the X-axis direction. Therefore, by rotating the radiation head 60 with the first swing mechanism 63 and the second swing mechanism 64, the points apart from the center point A
X-rays can be emitted from multiple directions. This enables three-dimensional irradiation that matches the shape of the affected area. Furthermore, by using the first swing mechanism 63 and the second swing mechanism 64, the traveling platform 62 and the frame 4
The irradiation direction of X-rays changes without moving 0, and X-rays are accurately irradiated even to the affected area that moves due to the patient's breathing, pulsation, internal organ movement, or the like.

The position at which the radiation head 60 is arranged is, for example, as shown in FIG. 7, when the frame 40 is oriented in the vertical direction and the radiation head 60 is arranged directly above the center point A. Can be represented by a rotation angle Ψ obtained by rotating the frame 40 around the axis B from the base point and a movement angle θ formed by the trajectory of the radiation head 60 around the center point A. Further, the distance the irradiation point moves in the X-axis direction when the radiation head 60 is rotated about the swing axis S by the rotation angle α is represented by the rotation angle Ψ and the movement angle θ. Further, the distance that the irradiation point moves in the Y-axis direction when the radiation head 60 is rotated about the swing axis T by the rotation angle β is also represented by the rotation angle Ψ and the movement angle θ. Therefore, the relationship between the rotation angle Ψ, the movement angle θ, the rotation angle α, the rotation angle β and the position of the irradiation point is obtained in advance,
By adjusting these angles, the irradiation point can be adjusted to a desired place.

Next, the treatment device control section 3 will be described with reference to FIGS. 8 and 9. The treatment device controller 3 is connected to the treatment device main body 2 by electric wiring, and remotely controls the treatment device main body 2. As shown in FIG. 8, the bed position information from the bed position detector that detects the position of the bed 30 is stored in the therapeutic device control unit 3 by the rotary encoder 53.
To the rotation angle ψ of the frame 40, the movement angle θ of the radiation head 60 from the sensor head 79, the rotation angle α around the swing axis S of the radiation head 60 from the optical encoder 63d, and the radiation head 60 from the optical encoder 64b.
The rotation angle β around the swing axis T of the X-ray is given by the dose measuring means 69 with the intensity of the X-ray. A bed controller 80 that controls the bed 30 from the treatment apparatus controller 3
In contrast, the bed movement command value, the tilting command value for the tilting control unit 81 that controls the tilting mechanism 50, and the movement commanding value for the movement control unit 82 that controls the moving mechanism 70 are the first swinging motions. A swing command value is given to the swing control unit 83 which controls the mechanism 63 and the second swing mechanism 64, and a radiation command value is given to the electronic linac control unit 84 which controls the electronic linac 60a.

After giving the tilt command value to the tilt control unit 81, the therapeutic device control unit 3 compares the rotation angle Ψ detected by the rotary encoder 63d with the rotation angle given by the tilt command value, and these When it is confirmed that the rotation angles match, the tilt control unit 81 is provided with a tilt command value for stopping the tilt mechanism 50. In addition, the treatment device control unit 3 gives a movement command value to the movement control unit 82, then compares the movement angle θ detected by the sensor head 79 with the movement angle given by the movement command value, and rotates these rotations. After confirming that the angles match, the tilt control unit 81 is provided with a tilt command value for stopping the tilt mechanism 50.

The treatment device controller 3 has a correction map 85 for correcting the irradiation direction of the X-rays emitted from the radiation head 60. The correction map 85 is obtained as follows, for example. First, the film is placed in the area including the center point A. Next, the first swing mechanism 63 and the second
The radiation head 60 is moved along the guide rail 42 without being driven by the swinging mechanism 64 of the frame 4 and
Irradiate X-rays toward the film while rotating 0. Then, the point where the X-rays are intensively irradiated is projected on the film. This point becomes the center point A.
Next, the radiation head 60 is rotated by the rotation angle Ψ1 and the movement angle θ1.
It is placed at a predetermined position given by and, and the film is irradiated with X-rays again. From the exposed film, how much the irradiation point of the irradiated X-ray is displaced from the center point A in the X-axis direction and the Y-axis direction is measured. From this measured amount, the rotation angle Δα for rotating the radiation head 60 by the first swing mechanism 63 and the radiation head 60 rotated by the second swing mechanism 64 in order to match the irradiation point of the X-ray with the center point A. The rotation angle Δβ for rotation is calculated. These calculated values, the rotation angle Ψ and the movement angle θ are written in the correction map. By repeating this operation, the correction map 85 showing the relationship between each position represented by the rotation angle Ψi and the movement angle θi and the rotation angle Δαi and the rotation angle Δβi for correcting the deviation of the irradiation point is obtained.

The correction map 85 can also be obtained as follows. First, instead of the radiation head 60, the laser generator is attached to the holding frame 62. A laser having a Gaussian distribution is emitted from this laser generator. Next, the light receiving surface of the CCD camera is set to match the center point A. Next, the laser generator is moved along the guide rail 42 and the frame 40 is rotated, and the laser is irradiated from the moved position toward the CCD camera. Then, the point where the light amount of the laser measured by the CCD camera becomes maximum is observed. This point is designated as the center point A. When this center point A coincides with the irradiation point of the laser emitted from the laser generator, the peak of the Gaussian distribution is observed at the center point A. Even when the laser is obliquely irradiated, if the irradiation point matches the center point A, the position where the peak of the Gaussian distribution is detected is the center point A. However, when the laser irradiation point is deviated from the center point A, the measured peak of the Gaussian distribution is observed at a position deviated from the center point A. Therefore, by measuring how much the observed position of the peak deviates from the center point A in the X-axis direction and the Y-axis direction, it can be expressed by the rotation angle Ψi and the movement angle θi as in the case of using the film. A correction map 8 representing the relationship between each position and the rotation angle Δαi and the rotation angle Δβi for correcting the deviation of the irradiation point.
5 is obtained.

The first swing mechanism 63 and the second swing mechanism 64 are controlled based on the correction map 85. Figure 9
As shown in FIG. 5, the treatment device control unit 3 calculates the information of the input rotation angle Ψi and movement angle θi by the first calculation means 90.
And the second calculation means 91, respectively. The first calculation means 91 determines the rotation angle Ψi, the movement angle θi, and a predetermined calculation formula, or the rotation angle αi and the rotation angle βi, and determines the swing command value that gives the rotation angle αi and the rotation angle βi. calculate. The calculated swing command value is sent to the swing control unit 3. The second calculation means 91 uses the correction map 85.
Rotation angle Δ that corrects the deviation of the irradiation point from the relationship obtained in
αi and the rotation angle Δβi are determined, and this rotation angle Δαi
And a correction command value that gives the rotation angle Δβi. The calculated correction command value is sent to the swing control unit 83.
The head swing control unit 83 drives the first head swing mechanism 63 and the second head swing mechanism 64 based on the correction command value and the head swing command value. Further, the swing control unit 83 controls the rotation angle α detected by each of the optical encoders 63d and 64b.
The detection result of j and the rotation angle βj is given to the swing control unit 83. The swing control unit 83 detects the detected rotation angle α.
j, the rotation angle βj, the rotation angle (αi + Δαi) given by the correction command value and the swing command value, the rotation angle (βi +
The comparison with Δβi) is performed, and when it is confirmed that they match, the first swing mechanism 63 and the second swing mechanism 64 are stopped.

As described above, in the radiotherapy apparatus 1,
Since the tilting mechanism 50 is controlled while confirming the rotation angle ψ detected by the rotary encoder 53, and the movement mechanism 70 is controlled while confirming the movement angle θ detected by the sensor head 79, the radiation head 60 is controlled by a predetermined amount. Placed securely in position.

Further, in the radiation treatment apparatus 1, the first swing mechanism 63 and the second swing mechanism 64 are controlled based on the rotation angle Ψ, the movement angle θ and the correction map 85, so that the radiation The deviation between the irradiation point and the center point A, which differ depending on the position of the head 60, is corrected, and the radiation head 6
The radiation head 60 is rotated by the rotation angle α and the rotation angle β suitable for the position where 0 is arranged. This makes it possible to perform irradiation with no positional error on the center point A and the area in the vicinity thereof from multiple directions. Moreover, the irradiation point and the center point A
The deviation between and can be easily corrected by rotating the radiation head 60 around two axes of the swing axis S and the swing axis T.

Further, in this radiotherapy apparatus 1, by using a calculation formula obtained from the relationship between the shape of the affected part and the rotation angle Ψi and the movement angle θi in the calculation formula given in advance to the first calculating means 91, It is possible to calculate the swing command value that gives the rotation angle αi and the rotation angle βi that are suitable for the shape. This makes it possible to perform three-dimensional irradiation that matches the shape of the affected area. Further, by detecting the rotation angle ψi and the movement angle θi, and the rotation angle αi and the rotation angle βi at which the radiation head 60 has rotated, it is possible to improve the reproducibility of irradiation.

Next, a procedure for performing radiation treatment on an affected area on the head using the radiation treatment apparatus 1 will be described. First, as shown in FIG. 10A, cross-sectional images of the affected area P are photographed from a plurality of directions using an X-ray CT examination apparatus. Since the affected part P made of soft tissue is less likely to be shaded in the image, a mark L that can identify the position of the affected part P such as the skull from the cross-sectional image is determined, and the affected part P can be positioned by this mark L when performing radiotherapy. To do so.
Further, from the shape of the affected part P, a calculation formula that gives a rotation angle Ψi and a movement angle θi suitable for the shape of the affected part P is determined. Next, this calculation formula, the captured cross-sectional image, and the treatment plan are input to the centralized control device. This centralized control device
The radiotherapy apparatus 1 includes a treatment device controller 3 and an image controller that controls an X-ray camera. Further, as shown in FIG. 10, the centralized control device includes a monitor 93 for displaying an image taken by an X-ray camera and a monitor 94 for displaying a cross-sectional image taken in advance. X
The position coordinates of the line CT examination apparatus are set to match the position coordinates of the radiation treatment apparatus 1.

When the radiation treatment is started, the patient 20 is placed on the bed 30 as shown in FIG. Next, FIG.
As shown in (b), a mark L that identifies the position of the affected area P is displayed on the monitor 94 with an X-ray camera, and the bed 30 is displayed until the mark L is arranged at a predetermined position while watching the image displayed on the monitor 94. To move. by this,
The affected area P is located at the center point A. After confirming that the mark L has been placed at a predetermined position, operate the centralized control device,
The tilting mechanism 50 and the moving mechanism 70 are driven to position the radiation head 60 at a predetermined position. While the tilting mechanism 50 and the moving mechanism 70 are moving, the rotary encoder 63
rotation angle ψ of the frame 40 between d and the sensor head 64b
And the movement angle θ of the radiation head 60 are respectively detected, and respective command values are given to the tilt control unit 81 and the movement control unit 82 based on these detection results, so that the radiation head 60 is reliably arranged at a predetermined position. It

After the radiation head 60 is placed at a predetermined position, the first swing mechanism 63 and the second swing mechanism 64 are moved to correct the deviation between the X-ray irradiation point and the center point A. While the first swing mechanism 63 and the second swing mechanism 64 are moving, each optical encoder 63d, 64b
The rotation angle α and the rotation angle β of the radiation head 60 are detected by the radiation head 60, and a swing command value based on the detection result is given to the swing control section 83, so that the radiation head 60 is reliably rotated by a predetermined angle. . After correcting the deviation between the X-ray irradiation point and the center point A, the electronic linac 60a
X-rays are generated from the X-rays, and the X-rays are irradiated toward the affected area P. When the irradiation at this position is completed, the irradiation of the X-ray is stopped, the tilting mechanism 50 and the moving mechanism 70 are driven again, and the radiation head 60 is arranged at another position. Then, X-rays are irradiated from this position toward the affected area P again. By repeating this operation, the affected area P located at the central point A is irradiated with X-rays from multiple directions.

The irradiation time of X-rays and the irradiation dose of X-rays are predetermined, and the irradiation time after the start of treatment and the irradiation dose of X-rays are shown in FIG.
As shown in (c), it is displayed on the monitor 94. When the irradiation of X-rays is started, the irradiation time displayed on the monitor 94 is counted down, and when the irradiation time becomes zero, the irradiation of X-rays is automatically stopped. The X-ray irradiation dose is displayed on the monitor at any time upon receiving a signal from the dose measuring unit 69. Even before the irradiation time displayed on the monitor becomes zero, the person who performs the treatment can stop the irradiation of the X-ray by operating the centralized control device.

If the treatment device controller 3 does not confirm that the radiation head 60 is normally moved, the irradiation of X-rays is automatically stopped.
This ensures the safety of radiation therapy. Furthermore, while the radiation head 60 is moving and rotating, it is controlled so that X-rays are not generated from the radiation head 60,
The dose of irradiation to normal tissue in the vicinity of the affected area P is minimized.

As described above, in the treatment using the radiation treatment apparatus 1, it is possible to accurately irradiate the affected area P located at the central point A with X-rays. Irradiation suitable for the shape of the affected area P can also be performed. Further, since the position and irradiation direction of the radiation head can be specified by the rotation angle Ψ, the movement angle θ, the rotation angle α, and the rotation angle β, the reproducibility of irradiation can be improved.

[0042]

As described above, according to the radiotherapy apparatus of the present invention, the following effects can be obtained. According to the radiation treatment apparatus of the first aspect, since the position error of the radiation source due to the assembly accuracy of the moving mechanism is unlikely to occur, the radiation source is reliably moved to the expected position. Thereby, the radiation can be accurately applied toward the center point of the arc.

According to the radiotherapy apparatus of the second aspect,
Since the load of the radiation source is dispersed and supported by the dispersion supporting portion, the frame is prevented from being distorted by the load of the radiation source. Thereby, the radiation can be accurately applied to the center point of the arc.

According to the radiotherapy apparatus of claim 3,
Since the load of the radiation source is dispersed and supported by the plurality of guide rails provided on the frame, distortion of the frame due to the load of the radiation source can be suppressed. Further, since the radiation source is guided along the guide rail forming the track, the radiation source moves accurately along the track. Thereby, the radiation can be accurately applied to the center point of the arc.

According to the radiotherapy apparatus of claim 4,
Since the tilting mechanism is controlled by the rotation angle Ψ of the frame and the moving mechanism is controlled by the moving angle θ of the radiation source, the radiation source is reliably arranged at a predetermined position. Thereby, the reproducibility of the radiation source position can be improved. Further, the error between the radiation irradiation point and the center point of the circular arc is corrected, and the irradiation direction suitable for the position of the radiation source is given. Thereby, it is possible to accurately irradiate the affected area having an irregular shape other than the spherical shape from multiple directions.

According to the radiotherapy apparatus of claim 5,
Since the first swing mechanism and the second swing mechanism are controlled based on the rotation angle α and the rotation angle β, the swing error of the radiation source is reduced. Further, since the first swing mechanism and the second swing mechanism are controlled also based on the rotation angle Ψ and the movement angle θ, the irradiation direction suitable for the position of the radiation source can be obtained. This makes it possible to reliably irradiate the desired point with the radiation. Further, by measuring the rotation angle α and the rotation angle β obtained by rotating the radiation source in accordance with the shape of the affected area, it is possible to improve the reproducibility of irradiation for an irregular shaped area other than a spherical shape.

According to the method for controlling a radiation treatment apparatus of the sixth aspect, the tilting mechanism and the moving mechanism are respectively controlled on the basis of the rotation angle Ψ and the moving angle θ, so that the radiation source can be surely set to a predetermined position. Placed in position. Thereby, the reproducibility of the radiation source position can be improved. Further, the error of the irradiation point is corrected, and the irradiation direction suitable for the position of the radiation source is given. This makes it possible to accurately irradiate radiation from multiple directions. Further, in the present invention, since the structure of the rotary drive shaft for positioning the radiation head is simple, the structure does not basically have the degree of freedom of entering the patient, which is a problem with the conventional device. In addition, even when there is concern about contact with the patient, it is easy to attach a mechanical limit or the like to physically prevent this, and it is safer than the conventional device.

[Brief description of drawings]

FIG. 1 is a front view of a radiation treatment apparatus showing a radiation treatment apparatus according to an embodiment of the present invention.

FIG. 2 is a top view of the radiotherapy apparatus according to the same embodiment.

FIG. 3 is a cross-sectional view of the radiotherapy apparatus taken along the line BB in FIG.

FIG. 4 is a front view of a radiation head and a moving mechanism.

FIG. 5 is a sectional view of a radiation head.

FIG. 6 is a side view of the radiotherapy apparatus according to the same embodiment.

FIG. 7 is a block diagram for explaining a treatment apparatus controller of the radiation treatment apparatus according to the same embodiment.

FIG. 8 is a view for explaining the operation of the radiotherapy apparatus according to the same embodiment.

FIG. 9 is a diagram showing a configuration of a circuit connected to a swing control section which constitutes a part of the treatment apparatus control section.

FIG. 10 is a diagram for explaining a treatment method using the radiation treatment apparatus according to the same embodiment.

[Explanation of symbols]

1 Radiation therapy device 40 frames 42 Guide rail (track and dispersion support) 45a, 45b Tilt axis 50 Tilt mechanism 53 Rotary encoder (second angle detector) 60 Radiation head (radiation source) 63 First swing mechanism 63d Optical encoder (third angle detector) 64 Second swing mechanism 64b Optical encoder (4th angle detector) 70 Moving mechanism 72 belt 72a Belt tensioner (holding part) 75a motor 77 Moving pulley (pulley) 79 Sensor head (first angle detector) 81 Tilt control unit 82 Movement control unit 83 Head swing control section 90 First calculating means 91 Second calculating means S Swing axis (uniaxial line) T Swing axis (other axis)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) A61N 5/10 A61N 5/10 S Z (72) Inventor Ichiro Yamashita 4-6 Kannon Shinmachi, Nishi-ku, Hiroshima-shi, Hiroshima No. 22 Mitsubishi Heavy Industries, Ltd. Hiroshima Research Institute (72) Inventor Yoshimi Oda 4-6-22 Kannon-Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd. Hiroshima Research Institute F-term (reference) 4C082 AA03 AC02 AE03 AG24 AG32 AG53 AG54 AJ02 AJ07 AJ08 AJ16 AL07 AP03 AP12 AP13 AR02 AR05

Claims (6)

[Claims] 1. A radiation therapy apparatus comprising: a frame having an arcuate trajectory, a radiation source movably supported along the trajectory, and a moving mechanism for moving the radiation source along the trajectory. The moving mechanism, a belt connected to the radiation source,
A holding unit arranged along the track to hold the belt, and a pulley that sends out the belt along the track.
A radiation therapy apparatus comprising: a motor for rotating the pulley. 2. A radiation treatment apparatus comprising a frame having an arcuate trajectory and a radiation source movably supported along the trajectory, wherein the frame distributes and supports the load of the radiation source. A radiation therapy apparatus comprising a support portion. 3. The radiation treatment apparatus according to claim 2, wherein the dispersion supporting portion is formed of a plurality of guide rails provided on the frame and forming the track. 4. A frame having an arcuate trajectory, a radiation source movably supported along the trajectory, a moving mechanism for moving the radiation source along the trajectory, and the trajectory drawing a spherical surface. A tilting mechanism for rotating the frame around a tilting axis, a first swinging mechanism for rotating the radiation source around one axis, and rotating the radiation source around another axis different from the one axis. In a radiotherapy apparatus having a second swing mechanism, a first angle detector that detects a rotation angle Ψ of the frame, a tilt control unit that controls the tilt mechanism based on the rotation angle Ψ, A second angle detector that detects a movement angle θ around the center of the trajectory defined by the trajectory of the radiation source, a movement control unit that controls the movement mechanism based on the movement angle θ, On the basis of the rolling angle Ψ and the moving angle θ first
First calculating means for calculating a swing command value for the swing mechanism and a swing command value for the second swing mechanism, respectively, and the rotation angle Ψ, the movement angle θ, and the radiation source. Second calculating means for respectively calculating a correction command value for the first swing mechanism and a correction command value for the second swing mechanism based on a relationship with a radiation irradiation point; A radiation therapy apparatus comprising: a swing control unit that controls the first swing mechanism and the second swing mechanism based on the correction command value. 5. The radiotherapy apparatus according to claim 4, wherein a third angle detector that detects a rotation angle α of the radiation source rotated by the first swing mechanism and the second swing mechanism are used. A fourth angle detector that detects a rotation angle β of the rotated radiation source, and the swing control unit based on the swing command value, the correction command value, the rotation angle α, and the rotation angle β. The radiation therapy apparatus is characterized in that: 6. A frame having an arcuate orbit, a tilting mechanism for rotating the frame around a tilt axis so that the orbit describes a spherical surface, and a first angle detection for detecting a rotation angle Ψ of the frame. A moving mechanism for moving the radiation source, a second angle detector for detecting a moving angle θ around the center of the trajectory defined by the trajectory of the radiation source, and A first swinging mechanism for rotating the radiation source, a third angle detector for detecting a rotation angle α of the radiation source rotated by the first swinging mechanism, and the radiation source different from the one axis. Method of controlling radiotherapy apparatus having second swing mechanism for rotating around other axis and fourth angle detector for detecting rotation angle β of radiation source rotated by the second swing mechanism And where A correction command value for the first swing mechanism and the second swing mechanism is calculated based on the relationship between the rotation angle ψ, the movement angle θ, and the irradiation point of the radiation emitted from the radiation, and the rotation is performed. A swing command value for the first swing mechanism and the second swing mechanism is calculated based on the angle Ψ and the movement angle θ, and the swing command value, the correction command value, the rotation angle α, and the A method of controlling a radiotherapy apparatus, characterized in that the first swing mechanism and the second swing mechanism are respectively controlled based on a rotation angle β.