Abstract:
The present invention relates to an irradiation device for irradiating an irradiation object with heavy charged particles at an irradiation station, comprising a particle accelerator for providing a particle beam and a swivelling device for swivelling the particle beam impinging on the irradiation object, wherein the swivelling device comprises a carrier pivotable about an axis. In accordance with the invention, the irradiation device is characterized in that the particle accelerator is mounted on the pivotable carrier.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is the U.S. National Phase of International PCT Application Serial No. PCT/EP2007/003116, filed Apr. 5, 2007, which claims priority to German Patent Application No. 20 2006 019 307.3, filed on Dec. 21, 2006, both of which are hereby incorporated by reference in their entirety for all purposes. 
     TECHNICAL FIELD 
     This invention relates to an irradiation device for irradiating an irradiation object with heavy charged particles, wherein the irradiation object is positioned at an irradiation station and is then irradiated with a particle beam impinging there. Heavy charged particles are understood to be charged particles which contain at least one nucleon (proton or neutron). Such devices are used for instance in cancer therapy for irradiating tumors with protons or heavier ions, e.g. He2+ or C6+. 
     BACKGROUND AND SUMMARY 
     A known proton therapy system with a plurality of treatment stations is described in U.S. Pat. No. 4,870,287. Such multi-station systems comprise a proton accelerator, typically an isochronous cyclotron or a synchrotron for providing a proton beam. Furthermore, the known multi-station systems comprise a beam guiding system for guiding the proton beam from the proton accelerator to the various treatment stations. In addition, the known devices include so-called gantries, which allow the proton beam to impinge from different directions on the irradiation object placed isocentrically at the irradiation station. Such gantry is a pivotally mounted device, in which the proton beam arriving along the swivel axis is coupled in, and in which the proton beam is deflected away and onwards from the swivel axis by a corresponding radiation optics, such that by rotating the gantry it impinges on the irradiation station, which mostly is located on the swivel axis of the gantry, from different directions. 
     In the known multi-station systems, only one particle accelerator is required for a plurality of treatment stations, so that the comparatively high expenditure for great accelerator facilities is distributed over a plurality of treatment stations. On the other hand, the multitude of treatment stations increases the total costs for the facility. In addition, comparatively large areas and buildings are required for the multi-station systems, which involves high costs in particular because of the radiation protection requirements. In multi-station systems, the treatment plans of the individual treatment stations must also be adjusted to each other, as it is not possible to simultaneously irradiate at different treatment stations. This leads to the further disadvantage that a delay at one treatment station involves a delay at the other treatment stations. 
     Therefore, it is the object of the present invention to propose an improved irradiation device. In particular, the irradiation device of the invention should have a compact configuration and require less space, so that the investment costs can be lowered as compared to known facilities. In addition, this invention should allow to omit the matching of treatment plans at various treatment stations. 
     In accordance with the invention, this object is solved by an irradiation device with the features of claim  1 . Preferred aspects can be taken from the sub-claims. 
     The irradiation device of the invention comprises a particle accelerator for providing a beam of heavy charged particles (particle beam). In accordance with the invention, the particle accelerator is mounted on a carrier pivotable about at least one axis. The carrier is part of a swivelling device, which is configured such that the particle beam directed onto the treatment station can be swivelled by rotating the carrier. For mounting on the carrier, in particular compact accelerators can be used. With the configuration of the irradiation device in accordance with the invention, a particularly compact single-station irradiation system can be realized. Mounting on the pivotable carrier allows a simplification of the beam guidance, as in particular coupling a stationary beam into the swivelling device can be omitted. 
     The swivelling device can be configured in particular in the manner of the known gantries. The pivotable carrier then advantageously constitutes a pivotable gantry frame. The accelerator then is mounted on this gantry frame and is swivelled with the same, so that coupling an externally generated beam fixed in space into the movable gantry structure can be omitted. 
     In a preferred aspect, the pivotable carrier has a bent structure with at least two legs, wherein the swivel axis extends through at least two legs. With such a structure, a particularly stable swivelling device can be realized. 
     Furthermore, the pivotable carrier preferably has a U-shaped structure, i.e. two substantially parallel side legs with a connecting piece. Advantageously, the swivel axis extends substantially vertically through the two legs of the U-structure. Furthermore advantageously, the accelerator is mounted in the terminal portion of a leg of the U-structure. The aforementioned preferred aspects provide for a particularly favorable weight distribution, so that the swivelling device can be rotated more easily. 
     Another advantageous aspect consists in that one leg of the U-structure is formed with an opening and/or recess in the vicinity of the swivel axis, so that a clearance is left in this leg in the vicinity of the swivel axis for placement of the irradiation object. This configuration provides for arranging the irradiation station in the region of this leg in the vicinity of the swivel axis, so that an irradiation object positioned there can be irradiated isocentrically. 
     Advantageously, means for guiding and/or shaping the particle beam are mounted on the carrier. With these means, the particle beam can be guided from the accelerator to the point of emission and can be shaped, for instance focussed or expanded, in the process. 
     In another preferred aspect, a means for modifying or reducing the particle energy, for instance an energy degrader, is mounted on the carrier. This means can be used for varying the energy of the particles impinging on the irradiation object. 
     In another preferred aspect, a radiation head or nozzle with components for the controlled emission of a particle beam in the direction of the irradiation station is mounted on the carrier. Advantageously, these components comprise one or more means which are configured such that an irradiation by the pencil-beam scanning method is possible. In the pencil-beam scanning method, a volume to be irradiated in the irradiation object is raster-scanned in three dimensions. For this purpose, the particle beam is focussed on a beam cross-section which lies distinctly below the size of typical irradiation volumes. Due to the Bragg peak, the major part of the radiation dose is deposited in a depth depending on the particle energy. By using a suitably focussed pencil beam, many small volumes, so-called voxels, thus can be irradiated, so that irradiation volumes of any shape—for instance tumors—can be raster-scanned with the pencil beam in three dimensions. The shift in beam direction, i.e. depth raster scanning in the irradiation object, is achieved by varying the particle energy, mostly by using an energy degrader. The shift in the two directions vertical to the beam, i.e. raster scanning in the plane vertical to the beam, is achieved by deflection means, in particular deflection magnets. For raster scanning by the pencil-beam scanning method, the components of the nozzle therefore advantageously comprise one or more means for deflecting vertical to the particle beam and/or a means for varying the particle energy and/or a means for monitoring the beam position and/or a means for monitoring the radiation dose. With such means, a particle beam shaped like a pencil beam can be used particularly advantageously for raster scanning an irradiation object. 
     In another preferred aspect, a cyclotron, in particular a superconducting synchrocyclotron, is used as particle accelerator. Advantageously, a cyclotron with a strong magnetic field is chosen, which can be realized in particular with a superconducting synchrocyclotron. Due to the strong magnetic field, the cyclotron can have a particularly compact configuration. It facilitates mounting on the swivelling device and its movement. In another preferred aspect, the device at the irradiation station includes a movable patient couch for positioning irradiation patients. Particularly advantageously, the patient couch can be moved translatorily in the horizontal plane and/or be rotated. This provides for positioning an irradiation patient such that a tumor to be irradiated is located inside the irradiation region covered by the irradiation device, and the tumor can be irradiated from different directions. 
     In accordance with another preferred aspect, the particle accelerator provides a beam of protons and/or heavier ions, in particular He2+ or C6+, as a beam of heavy charged particles. With the different irradiation particles, different treatment results can be achieved. 
    
    
     
       An embodiment of the invention will now be explained in detail below with reference to the Figures, in which: 
       BRIEF DESCRIPTION OF FIGURES 
         FIG. 1 : shows a top view of an irradiation device  1  of the invention with a U-shaped carrier  40 , 
         FIG. 2 : shows an oblique view of a device  1  of the invention, which provides a view into the recess  44  with the irradiation station  90 , 
         FIG. 3 : shows an oblique view of a device  1  of the invention, with a view onto the rear side of the recess  44 , and 
         FIG. 4 : shows a section through a nozzle  50 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows an irradiation device  1  of the invention in a top view. The carrier  40  of the swivelling device is configured as a gantry frame  40  with a U-shaped structure. The carrier or gantry frame  40  can be swivelled about the horizontal axis  30 . The swivel axis  30  extends vertically through the two legs  42 ,  43  of the U-structure, namely at about half the length of the legs. In the terminal region of the left leg  42 , the particle accelerator  20  is mounted on the gantry frame  40 . This particle accelerator is a particularly compact superconducting synchrocyclotron with a strong magnetic field. The particle accelerator provides a beam  10  of accelerated heavy charged particles, preferably protons. By using means  46  for beam guidance, the particle beam  10  is guided from the particle accelerator  20  along the U-structure of the gantry frame  40  to the nozzle  50 . The means for beam guidance in particular comprise deflection magnets  46 . Furthermore, focussing magnets  47  for focussing the particle beam  10  are mounted in the beam path. Alternatively or in addition, spreaders can be provided for beam expansion. In addition, an energy degrader  48  for modifying or reducing the particle energy is located in the beam path, likewise mounted on the gantry frame  40 . Via the nozzle  50 , the focussed particle beam or pencil beam is emitted in the direction of the irradiation station  90 . In the embodiment shown in  FIG. 1 , the leg  43  in the vicinity of the swivel axis  30  is configured as a large ring  45 , whose inner region forms a large round recess  44  whose center is located on the swivel axis. The irradiation station  90  is isocentrically arranged in the inner region  44  of the ring in the vicinity of the swivel axis. In the nozzle  50 , components  52 ,  54 ,  56 ,  58  are located, by means of which the emission of the particle beam in the direction of the irradiation station  90  can be controlled such that an irradiation object  80  can be irradiated by the pencil-beam scanning method. These components in the nozzle  50  comprise deflection means  52 ,  54 , in order to deflect the particle beam vertical to its direction. In particular, the deflection means can be two deflection magnets  52  and  54 , which deflect the particle beam in mutually orthogonal directions. Furthermore, the means in the nozzle  50  comprise means  56  for monitoring the beam position and means  58  for monitoring the radiation dose. 
       FIG. 2  shows an oblique view of the irradiation device of the invention, which provides a view into the recess  44  with the irradiation station  90 . The inner region  44  of the ring  45  forms a clearance or a recess, in whose center the swivel axis is located. The irradiation station  90  is arranged in the central region of the recess  44 , i.e. in the vicinity of the swivel axis. The nozzle  50 , from which the particle beam is emitted in the direction of the irradiation station  90  or irradiation object  80 , protrudes into the recess  44 . In  FIG. 2 , the legs  42 ,  43  of the U-structure are aligned approximately horizontally. By rotating the swivelling device, the ring  45  and with it the nozzle  50  rotates such that the particle beam directed onto the irradiation station  90  or impinging on the irradiation object  80  is swivelled. In this way, the direction from which the particle beam impinges on the isocentrically arranged irradiation station  90  can be varied by rotating the swivelling device. 
       FIG. 3  shows an oblique view of the irradiation device of the invention, which shows the recess  44 , in which the irradiation station  90  is located, from the rear. On the rear, the recess  44  is terminated by a rear wall  49 . 
       FIG. 4  shows a detailed view of a section through the nozzle  50 . The particle beam enters the nozzle at the point A and exits at the point B in the direction of the irradiation station  90 . The deflection magnets  52  and  54  serve for deflection of the particle beam in directions orthogonal to the beam direction and to each other. With the means  56 ,  58  in the exit region of the nozzle, the beam position and the radiation dose are monitored. 
     As is shown in particular in  FIG. 2 , a movable patient couch  92  is located at the irradiation station  90 , on which an irradiation patient  80  can be placed for tumor treatment. The patient couch  92  is rotatable in the horizontal plane and is also movable translatorily. In conjunction with swivelling the gantry frame  40  about the swivel axis  30 , it can therefore be achieved that a tumor in the irradiation patient can be irradiated from different directions. 
     With the invention described above, a number of advantages are achieved. The irradiation device of the invention can be formed particularly compact, in that all components required for beam generation, guidance, shaping and control are mounted on the pivotable carrier, so that it requires comparatively little space. Furthermore, in the irradiation device of the invention it is not necessary to adjust the treatment plans of a plurality of treatment stations to each other.