JPH11137699A - Radiotherapy equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To return an electron beam carrier system to its original position based on a detected change position while preventing equipment from being damaged with electron beams by displacement by operating an interlock circuit and stopping the operation of an electron beam accelerator through a means for detecting position deviation. SOLUTION: The figure shows a means for detecting changes in the positions of electromagnets 56 and 65 consisting of first and second electron beam carrier systems. A supporting pole 22 is attached on the side surface of the electromagnet 65, and a wire 24 having a weight 23 is hung at the top end. In this case, the wire 24 is passed through the center of a cylinder 17 and hung so that the top end of the weight 23 can indicate the center of an instruction panel 12 of a slide board 11. A stick-shaped member 25 is connected to a part, which corresponds to the cylinder 17, of the wire 24. When a built house is deformed by the earthquake or the passage of time and the positions of one of or both the electromagnets 65 and 66 are deviated, the member 25 is moved, photocouplers 19, 18, 20 and 21 are operated and the operation of the accelerator is stopped by the interlock circuit through a photocoupling circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises an electron beam accelerator and a gantry, detects a displacement of an electromagnet (bending magnet) constituting an electron beam transport system connecting them, and stops the operation of the electron beam accelerator. Along with
The present invention relates to a means for correcting the displacement.

[0002]

2. Description of the Related Art In an electron beam accelerator having excellent energy monochromaticity such as a microtron, an electron beam can be supplied to a plurality of gantry by using an electron beam transport system including an electromagnet and a vacuum pipe. . The feature of this system is that a plurality of gantry is installed for one electron beam accelerator, so that a patient can be set to another gantry while a patient is being treated with one gantry. In addition to shortening the time, the operating efficiency of the apparatus can be greatly improved, and the power supply and cooling water equipment of the entire radiotherapy apparatus can be centralized and saved as compared with the case where a plurality of radiotherapy apparatuses are installed.

[0003] Usually, this system is constructed in two dimensions,
The gantry and the electron beam transport system are installed on the same plane as the electron beam accelerator. However, depending on the configuration of the electron beam transport system, a plurality of gantry can be installed three-dimensionally on a different plane from the electron beam accelerator.

FIG. 5 shows two electron beam accelerators 50 with respect to one electron beam accelerator 50.
An example in which gantry units 51 and 52 are vertically arranged on different floors of a building is shown. The electron beam accelerator 50 and one gantry 51 are installed on the same floor of a building, and another gantry 52 is installed on another floor. The electron beam accelerator 50 and the gantry 51 are connected by a first electron beam transfer system including vacuum pipes 53, 54, 55 and electromagnets 56, 57, 58.

An electron beam accelerator 50 and another gantry 52 are provided by a second electron beam transport system comprising vacuum pipes 53, 59, 60 and electromagnets 56, 61, 62, 63, 64, 65. Are combined. There are basically two types of electromagnets, and the first type of electromagnets 57, 58 and 61, 62, 63, 64 are Q magnets each for converging an electron beam that gradually diffuses with transport.
The second type of electromagnets 56 and 65 are bending magnets for changing the traveling direction of the electron beam. The bending magnets 56 and 65 function to change the traveling direction of the beam on a plane parallel to the plane of the paper as indicated by the arrows in the figure. The Q magnets 58 and 64 are fixed to the side surfaces of the gantry 51 and 52. The Q magnets 57, 61, 62, 63 and the bending magnets 56, 65 are each held on a floor by a support device (not shown).

Each magnet is connected by a vacuum pipe whose inside is kept in a vacuum. At the joint between the vacuum pipe and the magnet, a flexible bellows is usually used for the purpose of facilitating the joining, and can absorb a slight displacement of the joint (not shown). .

In FIG. 5, when supplying an electron beam to the gantry 51 on the same floor as the electron beam accelerator 50, the bending magnet 56 of the electron beam transport system is not operated.
The Q magnets 57 and 58 act to allow the electron beam to travel straight to the gantry 51 as indicated by the dotted arrow. Electron beam accelerator 50
When the electron beam is supplied to the gantry 52 on the floor different from the above, the traveling direction of the electron beam is changed by the bending magnets 56, 65, and the Q magnets 61, 62,
It is squeezed by 63 and 64 to reach the target gantry 52.

[0008]

However, in the three-dimensional gantry configuration as described above, the building is deformed over time due to, for example, an earthquake or the like, and as a result, the position of the electron beam transport path is likely to change. If the electron beam transport path is deformed, not only does the electron beam not reach the gantry, but in some cases, the electron beam hits the wall of the transport path and damages it. If it is a two-dimensional deformation in a plane parallel to the paper, it can be handled by changing the magnetic field strength of the bending magnet following the deformation of the transport path, but if it is deformed in a direction perpendicular to the paper, If there is no bending magnet that bends the electron beam in this direction, it is impossible to cope with the current configuration of the electromagnet only by changing the magnetic field intensity. Further, even when the magnetic field intensity is changed in accordance with the deformation of the transport path, a means for detecting the amount of deformation of the transport path has not been devised so far.

SUMMARY OF THE INVENTION An object of the present invention is to detect a change in the position of an electromagnet constituting an electron beam transport system for transporting an electron beam to each gantry when a plurality of gantry are configured vertically, and to move the electromagnet to its original position. It is to provide a correction means for returning. Another object of the present invention is to provide a means for detecting a change in the position of the electromagnet even in the case of a single gantry and correcting the change.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a radiation therapy apparatus comprising a plurality of gantry for one electron beam accelerator, and in particular, a plurality of gantry is provided on different floors of a building. When it is installed vertically above, it has means for detecting a displacement of the bending magnets constituting the first and second electron beam transport systems, and the means for detecting the displacement activates an interlock circuit. The operation of the electron beam accelerator is stopped.

[0011] The present invention is further characterized in that a position adjusting means for correcting a displacement of the bending magnet in the horizontal and vertical directions is provided. Further, when one electron beam accelerator and at least one gantry are arranged on the same floor of the building, means for detecting the displacement of the bending magnet of the electron beam transport system and the horizontal position of the bending magnet And a position adjusting means for adjusting a vertical position shift.

[0012]

Embodiments of the present invention will be described below. FIG. 1 shows an electromagnet (bending magnet) 5 constituting the first and second electron beam transport systems, respectively.
6 shows means for detecting a change in the position of 6,65. Electromagnet 5
The scale 10 for indicating the position in the vertical direction is fixed to the side surface of 6. A slide plate 11 is provided so as to be able to slide up and down with respect to the scale 10. On the upper surface of the slide plate 11, an indicating board 12 on which a cross line or a concentric mark is drawn is set.
Further, the electromagnet 56 has four slits 13 at equal intervals,
A cylinder 17 having 14, 15, 16 is fixed. In this case, the cylinder 17 is fixed so that its center coincides with the center of the indicating board 12. One set of photocouplers 18 and 19 is arranged corresponding to the slits 13 and 15, and another set of photocouplers 2 is set corresponding to the slits 14 and 16.
0 and 21 are arranged. Although not shown, the photocouplers 18, 19, 20, and 21 are all attached to the electromagnet 56.

On the other hand, the support rod 22 is attached to the side surface of the electromagnet 65, and the wire 24 having the weight 23 at its tip is hung. In this case, the wire 24 passes through the center of the cylinder 17,
The tip of the dragon 23 is suspended so as to point to the center of the indicator panel 12 of the slide plate 11. A rod-shaped member 25 is connected to a portion of the wire 24 corresponding to the cylinder 17. The thickness of the member 25 is large enough to cover the width of the slits 13 to 16 of the cylinder 17 when the wire 24 is placed at the center of the cylinder 17.

FIG. 2 shows a means for interlocking the operation of the accelerator when the positions of the electromagnets 56 and 65 fluctuate more than a certain degree. The cylinder 17 and the member 25 are shown in a cross-sectional view. The photocouplers 18 and 19 are connected to an optical coupling circuit 30. Normally, light from the light emitting coupler 19 is cut off by the member 25 so as not to reach the light receiving coupler 18. Also, Photocoupler 2
0 and 21 are connected to the optical coupling circuit 31, and the optical coupling circuit 31 does not normally operate as described above. The optical coupling circuits 31 and 30 are the interlock circuit 3
2 are connected. The interlock circuit 32 generates a signal for interlocking the accelerator 50 when one or both of the optical coupling circuits 30 and 31 operate.

In the configuration shown in FIGS. 1 and 2, when the building is deformed due to an earthquake or aging, and one or both of the electromagnets 65 and 56 is displaced, as shown in FIG. In the direction shown, the photocouplers 19, 18 and 20, 21 are activated, and the interlock circuit 32 via the optical coupling circuits 30, 31 stops the operation of the accelerator 50. Next, detection of a change in the position of the electromagnet 65 will be described. The amount of the lateral displacement of the electromagnet 65 can be known from the extent of the lateral displacement of the tip of the weight 23 from the center of the indicating board 12. If the electromagnet 65 is displaced in the vertical direction, for example, is displaced upward, the wire 24 is pulled upward, so that a gap is formed between the tip of the weight 23 and the indicating board 12 by the displaced amount. At this time, the slide plate 11 is moved upward until the indicating board 12 contacts the tip of the weight 23. The amount of movement, that is, the amount of upward displacement of the electromagnet 65 can be known from the scale 10. When the electromagnet 65 is shifted downward, the wire 24 sags,
The weight 23 lies on the indicating board 12. In this state, when the slide plate 11 is slid downward such that the tip of the weight 23 contacts the indicating board 12, the amount of downward displacement of the electromagnet 65 can be known from the scale 10. Next, when the electromagnet 56 is displaced,
As the cylinder 17 moves relative to the member 25, the photocoupler operates and the interlock circuit 32 stops the operation of the accelerator. In addition, the amount of displacement of the electromagnet 56 in the left-right and up-down directions is determined by the
It can be known from 2 and the scale 10.

FIG. 3 shows an embodiment of a mechanism for adjusting the position of the electromagnet 65 in the horizontal and vertical directions. 3A is a plan view, and FIG. 3B is a cross-sectional view taken along line LL ′ of FIG. 3A. The gantry 33 is arranged on the floor. The mount 33 is provided with four screw rods 34 in a rectangular shape, and an adjustment plate 35 is attached to the screw rods 34 with washers 36 and nuts 37. A large screw hole 38 is formed in a portion of the adjustment plate 35 corresponding to the screw rod 34 so that the adjustment plate 35 can be moved in the X and Y directions. An electromagnet 65 is fixed on the adjustment plate 35. Further, a fixing frame 39 having an L-shaped cross section is attached to the screw rod 34 with a nut 40. Then, an X-direction push screw 41 and a Y-direction push screw 42 are provided on the fixed frame 39 from the X and Y directions, respectively, corresponding to the screw rods 34.

To adjust the position of the electromagnet 65 in the vertical direction, the nut 40 of the fixed frame 39 is loosened to
Can be moved up and down, and the position of the electromagnet 65 is adjusted by adjusting the nut 36 up and down. in this case,
By performing position adjustment on each of the four screw rods 34, it is possible to correct the positional deviation due to the left, right, up, and down of the electromagnet 65. When adjusting the electromagnet 65 in the horizontal direction, the position of the electromagnet 65 in the X direction can be adjusted by loosening the nut 37 and turning the X-direction push screw 41. The Y-direction position can be adjusted by turning the Y-direction push screw 42 to adjust the position of the electromagnet 65 in the Y direction. After the adjustment, the adjustment plates 35 and the fixing frame 39 are fixed by tightening the nuts 40 and 37. The adjustment range in the X and Y directions is limited by the size of the screw hole 38. The position adjustment of the electromagnet 65 has been described above.
A similar position adjustment mechanism is provided for 6. Electromagnet 6
The position adjustment of 5, 56 is completed by returning the weight to the original position.

The embodiments of the means for detecting the displacement of the electromagnet and the means for adjusting the position of the electromagnets provided on different floors of the building have been described above. One electron beam accelerator and one electron beam accelerator are provided on the same floor of the building. In the case where at least one gantry is provided, the present invention can be implemented also for an electromagnet (bending magnet) constituting the electron beam transport system. That is, for at least one electromagnet, a cylinder having a slit on its side and a photocoupler are installed, and further, a support rod provided on the same side is provided with a wire having a weight and a member corresponding to the slit of the cylinder, When the electromagnet is displaced, the movement of the member activates the photocoupler to interlock the accelerator. When the position of the electromagnet is shifted with respect to the electromagnet as in FIG. 3, the electromagnet is returned to the original position by this means.

FIG. 4 shows an embodiment of the horizontality detecting means installed on the side of the electromagnet. In this example, a block 70 having a horizontal plane whose horizontality is guaranteed is attached to each of the side of the electromagnet 65 in the electron beam traveling direction and the direction perpendicular thereto, and a level is set when the electromagnet is set. The degree of horizontality is obtained by using such a method and fixed in that state.
When the displacement of the suspended weight is observed, a level is applied to this block to check the horizontality, and the horizontal and vertical position adjustment mechanism of the electromagnet is used to return the weight to its original position. By adjusting, the position of the electromagnet can be returned to the original position.

[0020]

According to the present invention, it is possible to detect that the electron beam transport path is displaced due to the deformation of the building, and to prevent the apparatus from being damaged by the electron beam due to the displacement. Further, the position of the electron beam transport system can be easily returned to the original position based on the detected displacement amount. Even if a short-term displacement such as an earthquake occurs during treatment as well as a long-term deformation of the house, the treatment is immediately interrupted by this displacement detection mechanism and interlock mechanism linked to this. There is also an effect as a safety mechanism to protect the patient.

In the embodiment of the present invention, it is assumed that the position adjusting mechanism is manually adjusted. However, means for enabling remote control is provided in this mechanism, and a servo mechanism which works in conjunction with the displacement detecting mechanism is provided. If this is the case, the position can be adjusted immediately in response to the displacement. However, in the event of an earthquake, treatment should be interrupted rather than continued, and long-term displacements should be adjusted manually by regularly monitoring displacements and manually adjusting them. Is considered sufficient. This is also advantageous in terms of the cost of the device.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a block diagram of an interlock according to an embodiment of the present invention.

FIG. 3 is a plan view (a) and a cross-sectional view (b) showing a configuration of a horizontal and vertical position adjusting mechanism of an electromagnet according to an embodiment of the present invention.
It is.

FIG. 4 is a three-dimensional view showing an embodiment of a flatness detecting means of the electromagnet.

FIG. 5 is a side view illustrating a configuration example of a two-gantry system configured in a vertical direction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Scale 11 Slide plate 12 Indicator board 13, 14, 15, 16 Slit 17 Cylinder 18, 19, 20, 21 Photocoupler 24 Wire 31, 30 Optical coupling circuit 32 Interlock circuit 33 Mount 34 Screw rod 39 Fixed frame 41, 42 Set screw 50 Accelerator 51,52 Gantry 56,65 Electromagnet

Claims (1)

[Claims] 1. A radiation therapy apparatus comprising a plurality of gantry for one electron beam accelerator, particularly when a plurality of gantry are vertically installed on different floors of a building, the first and second radiotherapy apparatuses are provided. It has a means for detecting a displacement of a bending magnet constituting the electron beam transport system, and the means for detecting the displacement activates an interlock circuit to stop the operation of the electron beam accelerator. Radiation therapy equipment.