JP4450210B2 - Light projection device and radiation therapy system provided with the same - Google Patents

Description

  The present invention relates to a light projecting device used for confirming an irradiation field during radiotherapy and a radiotherapy system including the same.

  Radiotherapy methods are known in which an affected area of a patient such as cancer is irradiated with X-rays or particle beams such as protons or carbon ions. The radiation irradiation field is formed by a collimator, an aperture, a compensator, or the like in the irradiation field forming apparatus, and irradiates the affected area intensively. At this time, it is important to check the irradiation field with high accuracy so that the radiation is emitted only to the affected area and does not damage normal cells.

  As a method for confirming such an irradiation field, conventionally, there has been performed a method in which a projector is mounted in an irradiation field forming apparatus for forming an irradiation field, and light from the projector is projected onto the body surface of a patient to be treated. (For example, refer to Patent Document 1 and Patent Document 2). In these conventional technologies, the light source lamp of the projector, which is the light source position of the light irradiation field, is arranged at the downstream side position of the radiation source, and when checking the irradiation field, the light from the light source lamp is reflected in the beam axis direction of the radiation using a reflecting mirror. The light irradiation field is formed on the patient body surface.

JP-A-5-76613 Japanese Patent Laying-Open No. 2004-209259 (FIG. 16)

  When the irradiation field is confirmed by the projector as in the above-described prior art, it is necessary to virtually match the radiation source and the light source position of the light irradiation in order to match the radiation irradiation field and the light irradiation field. Therefore, it is necessary to install the light source lamp of the projector, which is the light source position of the light irradiation field, at a position where the radiation source and the SAD (Source Axis Distance) are equal.

However, there are the following problems in the above-described prior art.
That is, in the above prior art, although not clearly described in the specification, the projector is usually fixedly installed and the light source position (the position of the light source lamp) is constant. In the prior art described in Patent Document 1, there is a description that the light source position is moved to adjust the irradiation field. However, in this conventional technique, the light source position is moved by adjusting the irradiation direction (light source position). For adjusting the position on the axis of the radiation source), and the source distance is almost constant.

  Here, in the case of a particle beam therapy apparatus in which charged particles such as protons are used as radiation and a charged particle beam accelerated to a predetermined energy by an accelerator forms an irradiation field in the irradiation apparatus and irradiates the affected area, the patient (or the affected area) ), The conditions of the radiation field are different, so that the position of the radiation source changes every time the patient (or affected area) changes, unlike the case where the position of the radiation source (the position of the X-ray tube) is constant as in the X-ray therapy apparatus (In this case, the virtual radiation source position of the particle beam) changes. Therefore, when a projector with a fixed light source position as in the prior art is applied to the particle beam therapy system, the radiation source position and the light source position are shifted, and the accuracy of irradiation field confirmation is reduced.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a projector capable of maintaining a good accuracy in confirming an irradiation field even when the radiation source position fluctuates, and the same. It is providing the radiotherapy system provided with.

(1) In order to achieve the above object, the first invention of the present application is directed to the surface of the patient's body in the radiation treatment in which the irradiation target is irradiated with the particle beam through the irradiation field forming device equipped with the range modulator. In a light projecting device for confirming a radiation irradiation field by projecting, a light source, an optical lens device capable of adjusting a focal position of a light beam from the light source, a reflecting mirror for changing the direction of the light beam from the light source , The optical lens device calculates a virtual source position of the particle beam existing in the range modulator based on treatment plan information, and the focal position of the light beam becomes the calculated virtual source position. And a control device for adjusting the frequency .

In the present invention, before performing therapeutic irradiation of radiation (particle beam) , light is projected from the light projecting device onto the patient's body surface to confirm the radiation irradiation field.

Here, in the case of a particle beam therapy apparatus in which charged particles such as protons are used as radiation and a charged particle beam accelerated to a predetermined energy by an accelerator forms an irradiation field in an irradiation field forming apparatus and irradiates the affected part. Since the conditions of the irradiation field are different for each (or affected area), the radiation is changed every time the patient (or affected area) changes, unlike the case where the position of the radiation source (the position of the X-ray tube) is constant, as in an X-ray treatment apparatus, for example The source position (in this case, the virtual source position of the particle beam existing in the range modulator ) changes.

At this time, in the present invention, the virtual source position of the particle beam existing in the range modulator is calculated based on the treatment plan information so that the focal position of the light beam becomes the calculated virtual source position. By adjusting the optical lens device, it is possible to make the focal position of the light beam coincide with the position of the radiation source and to make it equivalent to that emitting light from the radiation source. As a result, even if the patient (or affected area) changes and the radiation source position changes as in the particle beam therapy system, the radiation source and the light source position of light irradiation are virtually controlled by adjusting the focal position of the light beam. Therefore, the irradiation field confirmation accuracy can be maintained well. As a result, it is possible to improve the irradiation accuracy of the radiation treatment irradiation and improve the safety of the treatment. Furthermore, since the positioning accuracy of the patient can be improved, the positioning operation can be shortened, which can contribute to the high efficiency of the treatment.

  (2) According to a second invention of the present application, in the first invention, the optical lens device includes a condensing lens for condensing the light beam from the light source, a focus adjusting lens for adjusting a focal length, and It has a lens drive device which adjusts the lens position of the condensing lens and the focus adjustment lens.

(3) In a third invention of the present application, in the second invention described above, the control device controls the lens driving device so that the focal position of the light beam becomes the calculated virtual radiation source position, thereby condensing the light. adjust the use lenses the lens position of the focus adjusting lens and said and Turkey.

  (4) The fourth invention of the present application is characterized in that, in the second or third invention, the condensing lens is a convex lens or an aspherical short focus lens, and the focus adjusting lens is a concave lens.

(5) To achieve the above object, the present fifth invention, in the radiation therapy system for treating by irradiating a particle beam to an irradiation target, the particle beam generator for generating a particle beam, in the particle beam generator an irradiation device for irradiating the generated particle beam to said irradiation object, characterized in that a one Kano light projecting device of the first to fourth aspects.

  ADVANTAGE OF THE INVENTION According to this invention, the confirmation precision of the radiation irradiation field in radiotherapy can be improved.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a light projecting device of the present invention and a radiation therapy system including the same will be described with reference to the drawings.

  FIG. 1 is a diagram showing an overall schematic structure of a particle beam therapy system which is an embodiment of a radiation therapy system of the present invention.

  In FIG. 1, ions (for example, protons) generated from an ion source (not shown) are accelerated by a pre-accelerator 1 and incident on a synchrotron (radiation generator) 2. The incident ion beam is accelerated by the synchrotron 2 and is increased to the set energy, and then is emitted from a deflector for extraction (not shown) and passes through the beam transport system 3 to form an irradiation field in each treatment room 4. It is carried to a device (irradiation device) 5 (see FIG. 2).

  FIG. 2 is a side sectional view showing the internal configuration of the irradiation field forming apparatus 5.

  In FIG. 2, an ion beam incident on the treatment room 4 via the beam transport system 3 is incident on the irradiation field forming device 5 from the vacuum duct 6, and the range modulator 7 (in this embodiment, RMW (range modulation). A SOBP (Spread Out Bragg Peak) is formed by a ridge filter or the like. Then, an ion beam is formed in an optimum shape for the lesion of the patient 11 by the scatterer 8, the range shifter 9, the snout aperture and the compensator 10. The virtual particle source position 12 of the ion beam is located in the range modulator 7 as shown in FIG.

  The range modulator 7 is provided so as to be movable in a direction substantially perpendicular to the beam axis 16 (in the direction of an arrow in FIG. 3 to be described later) together with an X-ray fluoroscopic device 15 for performing X-ray imaging when positioning the patient 11. Is mounted on the table 17 and moved onto the beam axis 16 as necessary. The light projecting device 19 for confirming the radiation field by projecting light onto the body surface of the patient 11 can move in a direction substantially perpendicular to the beam axis 16 (in the direction of the arrow in FIG. 3 described later). It is mounted on a table 20 and is moved onto the beam axis 16 as necessary.

  FIG. 3 is a diagram showing a state in which the range modulator 7, the X-ray fluoroscope 15 or the light projecting device 19 is moved on the beam axis 16 by the movement of the tables 17 and 20.

  As shown in FIG. 3, when the table 17 moves, the range modulator 7 and the X-ray fluoroscope 15 have their virtual particle source position 12 and X-ray source position 18 at the irradiation center (isocenter). ) To the same SAD (Source Axis Distance: hereinafter referred to as a source distance). That is, when the patient 11 is positioned and the treatment irradiation is performed so that the X-ray fluoroscopic device 15 is positioned on the beam axis 16 at the time of X-ray imaging at the time of positioning the patient 11, the range modulator 7 is used. The table 17 moves so as to be positioned on the beam axis 16.

  For example, when the radiation field is confirmed by projecting light onto the body surface of the patient 11 in the previous stage of performing the X-ray imaging, the table is set so that the light projecting device 19 is positioned on the beam axis 16. 20 moves. At this time, as shown in FIG. 3, the light beam from the light source 22 of the light projecting device 19 is focused on the virtual particle source position 12 by a combination of lenses (details will be described later).

  FIG. 4 is a conceptual diagram conceptually showing the internal structure of the light projecting device 19.

  As shown in FIG. 4, the light projecting device 19 projects a non-uniform projection such as a light source 22 such as a halogen lamp, a reflective concave mirror 23 for improving the light collection efficiency of the light source 22, and a shadow of the light source filament. The diffusion lens 24 for preventing, the convex lens (condensing lens) 25 for condensing, the concave lens (focus adjusting lens) 26 for adjusting the focal length, and the direction of the light beam from the light source 22 in the direction of the beam axis 16 (Refer to the focal point of the light beam is located on the beam axis 16). An aspherical short focus lens may be used in place of the condensing convex lens 25. In this case, a projector with higher illuminance can be realized. The light source 22 is not limited to a halogen lamp, and may be a high intensity ionization (HID) lamp, for example. In this case, it is possible to project light on an object to be irradiated at a longer distance.

  FIG. 5 is a table showing the relationship between the distance between the concave and convex lenses 25 and 26 and the distance from the light source 22 to the focal point 28.

  In FIG. 5, R1 is the radius of the light beam at the convex lens 25, R2 is the radius of the light beam at the concave lens 26, d is the distance between the concave and convex lenses 25 and 26, and L is the distance from the light source 22 to the focal point 28. As shown in FIG. 5, the distance L from the light source 22 to the focal point 28 increases as the distance d between the concave and convex lenses decreases, and conversely, the distance L from the light source 22 to the focal point 28 increases as the distance d between the concave and convex lenses increases. Becomes smaller. In the light projecting device 19 of this embodiment, the distance L from the light source 22 to the focal point 28 can be adjusted in the range of about 530 mm to about 130 mm by changing the distance d between the concave and convex lenses in the range of 20.1 mm to 56 mm. Is possible.

  FIG. 6 is a conceptual diagram conceptually showing the overall configuration of the lens driving device 30 that drives the convex lens 25 and the concave lens 26 of the light projecting device 19.

  In FIG. 6, the lens driving device 30 includes a convex lens driving device 30A and a concave lens driving device 30B. The convex lens driving device 30A is rotated by a convex lens driving motor 31 for driving the convex lens 25 and the convex lens driving motor 31. A ball screw 32, a bearing 33 that rotatably supports the opposite side of the ball screw 32 to the convex lens driving motor 31, and the ball screw 32, and the ball screw 32 is rotated by the convex lens driving motor 31. And a convex lens holder 34 for moving the convex lens 25 in the axial direction of the light beam according to the rotation amount. Similarly, the concave lens driving device 30B includes a concave lens driving motor 35 for driving the concave lens 26, a ball screw 36 rotated by the concave lens driving motor 35, and a side opposite to the concave lens driving motor 35 of the ball screw 36. A bearing 37 to be supported and a concave lens holder 38 which is screwed with the ball screw 36 and moves the concave lens 26 in the axial direction of the light according to the rotation direction and the amount of rotation when the ball screw 36 is rotated by the concave lens driving motor 35. I have.

  The lens driving device 30 (more specifically, the concave and convex lens driving motors 31 and 35) having the above-described configuration is controlled and driven by an irradiation control device (control device) 40. FIG. 7 is a diagram illustrating an automatic control system of the lens driving device 30 (concave / convex lens driving motors 31 and 35).

  As shown in FIG. 7, first, treatment plan information (beam energy or the like) of the patient 11 is transmitted from the treatment plan database 41 to the central control device 43 through a network (for example, LAN or the Internet) 42.

  On the other hand, the range modulator 7 (which uses RMW in this embodiment as described above. A ridge filter or the like may be used) prepares various patterns according to the irradiation field, but prevents misuse. Each ID management is performed. By mounting the range modulator 7 in the irradiation field forming device 5, the ID number information is taken into the irradiation control device 40 and further transmitted from the irradiation control device 40 to the central control device 43. The central controller 43 uses the treatment plan information such as beam energy sent from the treatment plan database 41 and the ID number information of the range modulator (RMW) 7 sent from the irradiation controller 40, The source distance of the virtual particle source position 12 is calculated. Further, based on the relationship between the distance d between the concave and convex lenses 25 and 26 calculated in advance and the distance L from the light source 22 to the focal point 28 (see, for example, FIG. 5), the calculated virtual particle source position 12 and the focal point 28 are calculated. The distance d between the concavo-convex lenses 25 and 26 is calculated so that the positions of are coincident with each other. The calculation result is transmitted to the irradiation control device 40.

  The irradiation control device 40 to which the distance d between the concave and convex lenses 25 and 26 is input from the central control device 43 controls the lens driving device 30 (specifically, the concave and convex lens driving motors 31 and 35) to control the concave and convex lenses 25 and 26. The concavo-convex lenses 25 and 26 are moved so that the distance d becomes the input value.

  In the above description, the concave and convex lenses 25 and 26 are moved based on the distance d between the concave and convex lenses 25 and 26 calculated by the central controller 43. However, the present invention is not limited to this, and the central controller 43 causes the concave and convex lenses 25 and 26 to move. The respective lens positions (distance from the light source 22 and the like) of 26 may be calculated, and the concave and convex lenses 25 and 26 may be moved based on the calculated positions.

  In the above, the concavo-convex lenses 25 and 26 and the lens driving device 30 constitute an optical lens device capable of adjusting the focal position of the light beam from the light source described in the claims.

  Next, the operation of the embodiment of the light projecting device of the present invention having the above-described configuration and the radiation therapy system including the same will be described below.

  When the radiation field is confirmed in a state where the patient 11 is roughly positioned, the operator first moves the table 17 so that the range modulator 7 and the X-ray fluoroscope 15 are placed on the beam axis 16. Evacuate from. Next, the table 20 is moved so that the light beam emitted from the light projecting device 19 coincides with the beam axis 16.

  In the light projecting device 19, as described above, the irradiation control device 40 controls the lens driving device 30 so that the virtual particle source position 12 and the position of the focal point 28 coincide with each other based on the treatment plan information of the patient 11. The concavo-convex lenses 25 and 26 are moved. Then, light is emitted from the light source 22 in a state where the virtual particle source position 12 and the position of the focal point 28 coincide with each other, and the radiation irradiation field is projected onto the body surface of the patient 11. At this time, if necessary, the irradiation field is marked on the body surface of the patient 11 with a special ink or the like by a doctor or the like using the projected irradiation field as an index. In this way, the radiation field is confirmed visually.

  Next, the table 17 is moved, and the X-ray fluoroscope 15 is moved onto the beam axis 16. The light projecting device 19 is retracted from the beam axis 16 as the table 20 moves. Then, X-rays are emitted from the X-ray fluoroscopic apparatus 15 toward the affected part of the patient 11 and X-ray imaging is performed. Thus, the image captured and the tomographic image created from the X-ray CT image captured at the time of treatment planning are compared by, for example, the central control device 43, and the deviation of coordinates is calculated. The bed on which the patient 11 lies is moved so as to eliminate this shift, and further detailed position adjustment is performed.

  Thereafter, the table 17 is moved, the X-ray fluoroscope 15 is retracted from the beam axis 16, and the range modulator 7 is moved onto the beam axis 16. Then, ions generated in the ion source are accelerated by the synchrotron 2 and are transported to the irradiation field forming device 5 in the treatment room 4 through the beam transport system 3. The ion beam incident on the irradiation field forming device 5 forms an irradiation field based on the treatment plan information by the range modulator 7 and the like, and is irradiated to the affected part of the patient 11.

According to the embodiment of the present invention described above, the following effects can be obtained.
That is, in the particle beam therapy system according to the present embodiment, as described above, before performing radiation treatment irradiation, light is projected from the light projecting device 19 onto the body surface of the patient 11 to confirm the radiation irradiation field. .

  Here, as in the particle beam therapy system according to the present embodiment, the irradiation field forming apparatus 5 forms an irradiation field using an ion beam accelerated to a predetermined energy by using a charged particle such as a proton and the patient 11 When irradiating the affected area, the conditions of the irradiation field are different for each patient 11 (or affected area). For example, unlike the case where the position of the radiation source (the position of the X-ray tube) is constant as in the X-ray treatment apparatus, Every time 11 (or affected part) changes, the virtual particle source position 12 changes.

  At this time, in the present embodiment, as described above, the focal position 28 of the light beam from the light source 22 is adjusted by the concave and convex lenses 25 and 26 and the lens driving device 30, so that the focal position 28 of the light beam is a virtual particle source. It can coincide with the position 12 and can be equivalent to emitting light from the virtual particle source position 12. As a result, even when the patient 11 (or affected part) changes and the virtual particle source position 12 changes as described above, the virtual particle source position 12 and the light irradiation light source are adjusted by adjusting the focal position 28 of the light beam. Since the position (ie, the focal position 28) can be virtually matched, the irradiation field confirmation accuracy can be maintained well. As a result, it is possible to improve the irradiation accuracy of the therapeutic irradiation of the radiation and improve the safety of the treatment. Furthermore, since the positioning accuracy of the patient 11 can also be improved, the positioning work can be shortened, which can contribute to higher efficiency of treatment. Furthermore, as a result of improving the positioning accuracy, the number of times of positioning by X-ray imaging can be reduced, and the exposure of the patient 11 can be reduced.

  Moreover, according to this embodiment, the improvement effect of the freedom degree of installation of the light projector 19 can be acquired. That is, according to the structure in which no lens is used as in the above-described prior art, the light source 22 has only to be arranged on the downstream side of the virtual particle source position 12, but according to the present embodiment, the light from the light source 22 is emitted. Since the focal point 28 is formed by focusing by the convex lens 25, the light projecting device 19 can be arranged upstream of the virtual particle source position 12 as in the present embodiment. Therefore, the freedom degree of installation of the light projector 19 can be improved.

  Furthermore, according to this embodiment, the space in the irradiation field forming device 5 can be used effectively. That is, when the light projecting device 19 does not have a lens structure as in the present embodiment, the range modulator 7, the X-ray fluoroscopic device 15, and the light projecting device 19 are placed on the same table 45 as shown in FIG. When the table 45 is moved in a direction substantially perpendicular to the beam axis 16, the virtual particle source position 12, the X-ray source 18 and the light source 22 are moved from the irradiation center (isocenter) to the same radiation source. A structure in which the particle beam irradiation field, the X-ray irradiation field, and the light irradiation field are combined with high precision in principle can be considered according to the distance. However, in the structure of this comparative example, the movement width of the table 45 is large, and the space in the width direction in the irradiation field forming apparatus 5 is occupied. Furthermore, this results in an increase in the size of the irradiation field forming device 5. In contrast, in the present embodiment, since the light projecting device 19 is installed on the upstream side in the beam axis direction, it can be used effectively without occupying the space in the width direction in the irradiation field forming device 5.

  Furthermore, according to the present embodiment, an effect of simplifying the structure can be obtained. That is, in the structure that does not use a lens as in the above-described prior art, a structure including a driving device that moves the light projecting device itself is conceivable in order to move the light source position. On the other hand, according to the present embodiment, the light source position can be adjusted by adjusting the focal position 28 of the light beam from the light source 22 by mounting the driving device 30 that moves the concave and convex lenses 25 and 26. The structure of the driving device can be simplified and the structure can be simplified as compared with the structure provided with the driving device for the light projecting device.

  In the above-described embodiment, the light projecting device 19 is disposed on the upstream side of the virtual particle source position 12, but not limited thereto, the light projecting device 19 is disposed on the downstream side of the virtual particle source position 12. Is also possible. FIG. 9 shows a conceptual configuration diagram in the case of arrangement on the downstream side. With such a configuration, the same effect as that of the above embodiment can be obtained, and the position of the light source 22 can be brought closer to the patient 11, so that the illuminance of the light beam can be increased.

  In the above embodiment, the concave and convex lens driving motors 31 and 35 of the lens driving device 30 are driven by the control of the irradiation control device 40 so that the concave and convex lenses 25 and 26 are automatically moved. For example, the operator may manually rotate the ball screws 32 and 36 to move the concave and convex lenses 25 and 26 using a handle or the like.

It is a figure showing the whole schematic structure of the particle beam therapy system which is one Embodiment of the radiotherapy system of this invention. It is a sectional side view showing the internal structure of the irradiation field forming apparatus with which one embodiment of the radiotherapy system of the present invention is equipped. It is the figure which showed a mode that the range modulator, the X-ray fluoroscope, or the light projection apparatus was moved on the beam axis by the movement of a table. It is a conceptual diagram which represents notionally the internal structure of one Embodiment of the light projection apparatus of this invention. It is a table | surface which shows the relationship between the distance between uneven | corrugated lenses, and the distance from a light source to a focus. It is a conceptual diagram which represents notionally the whole structure of the lens drive device which drives a convex lens and a concave lens. It is a figure showing the automatic control system of a lens drive device. It is a partial side view showing the structure of the comparative example which mounted the range modulator, the X-ray fluoroscopy apparatus, and the light projector on the same table. It is a partial side view showing the structure of the modification which has arrange | positioned the light projector to the downstream of a virtual particle source position.

Explanation of symbols

2 Synchrotron (radiation generator)
5 Irradiation field forming device (irradiation device)
11 Patient 19 Projection device 22 Light source 25 Convex lens (optical lens device, condensing lens)
26 Concave lens (optical lens device, focus adjustment lens)
27 Reflector 30 Lens drive device (optical lens device)
40 Irradiation control device (control device)

Claims (5)

In the light projection device for confirming the radiation field by projecting light onto the patient's body surface during the radiation treatment for irradiating the irradiation target with the particle beam through the irradiation field forming device equipped with the range modulator ,
A light source;
An optical lens device capable of adjusting a focal position of a light beam from the light source;
A reflecting mirror for changing the direction of light rays from the light source ;
The optical lens device calculates a virtual source position of the particle beam existing in the range modulator based on treatment plan information, and the focal position of the light beam becomes the calculated virtual source position. And a control device for adjusting the light.   The optical lens device includes a condensing lens for condensing a light beam from the light source, a focus adjustment lens for adjusting a focal length, and lens positions of the condensing lens and the focus adjustment lens. The light projecting device according to claim 1, further comprising a lens driving device for adjustment. Wherein the control device, such that the focal point position before Symbol ray is virtually source position where the calculated, adjusting the lens position of the lens drive device and the control to the condensing lens the focusing lens light projecting device of claim 2, wherein the Turkey.   4. The light projection device according to claim 2, wherein the condensing lens is a convex lens or an aspherical short focus lens, and the focus adjustment lens is a concave lens. In a radiotherapy system that irradiates a target with a particle beam and treats it,
A particle beam generator for generating particle beams ;
An irradiation apparatus for irradiating the irradiation object with the particle beam generated by the particle beam generation apparatus;
A radiation therapy system comprising: the light projecting device according to claim 1.

Images