Abstract:
A mount for a radiotherapy apparatus may include a cylindrical bearing surface to allow the mount to be supported in a rotateable manner, a housing extending from the bearing surface and having an extent in a direction along an axis of the cylindrical bearing surface, the mount having an axial through-hole which encompasses the axis of the cylindrical bearing surface, the housing having at least one opening communicating with the through-hole and extending in a direction transverse to the axis of the cylindrical bearing surface.

Description:
FIELD OF THE INVENTION 
   The present invention relates to radiotherapy apparatus, and parts thereof including the supporting structures upon which the various active elements of the apparatus are mounted. 
   BACKGROUND ART 
   Radiotherapeutic apparatus is provided in a range of different morphologies to suit the particular type of treatment format that it is to provide. This includes gantry arrangements, in which a projecting arm carries a radiation source and is rotatable about an axis that is offset from the arm and coincident with the beam direction. It also includes arrangements in which a source is rotatable within a toroidal shell, into which a patient is placed. 
   SUMMARY OF THE INVENTION 
   This variety of arrangements reduces the flexibility of manufacturing processes and increases development costs. If certain elements of the apparatus could be made common to more than one arrangement then development costs could be shared, inventory could be reduced, and production processes could be made more flexible. 
   The present invention therefore provides a mount for a radiotherapy apparatus, comprising a cylindrical bearing surface to allow the mount to be supported in a rotatable manner, a housing extending from the bearing surface and having an extent in a direction along an axis of the cylindrical bearing surface, the mount having an axial through-hole which encompasses the axis of the cylinder, the housing having at least one opening communicating with the through-hole and extending in a direction transverse to the axis of the cylinder. 
   This mount can be used as the basis for a number of different radiotherapy systems. One such system comprises a support having a cylindrical bearing surface on which is mounted the cylindrical bearing surface of such a mount, an arm extending from a side of the mount in a direction in line with the axis of the cylindrical bearing surface, the arm comprising a linear accelerator adapted to emit a beam of therapeutic radiation from an end portion of the arm in a direction transverse to and towards the axis of the cylindrical bearing surface. 
   This system can further comprise one or more of a source of diagnostic radiation, a detector for diagnostic radiation and a detector for therapeutic radiation. These can be mounted on retractable arms, so as to be selectively retractable into the mount or extendable alongside the linear accelerator. 
   Typically, therapeutic radiation has an energy of at least 1 MeV and diagnostic radiation has an energy of at least 1 keV. 
   Another possible system comprises a support having a cylindrical bearing surface on which is mounted the cylindrical bearing surface of such a mount, a source of therapeutic radiation fixed to the mount and adapted to emit a beam transverse to and towards the axis of the cylindrical bearing surface though the at least one opening of the mount. 
   This system can also further comprise one or more of a source of diagnostic radiation, a detector for diagnostic radiation and a detector for therapeutic radiation. 
   It can further include a cover around the mount, the cover including a concave region extending into the axial through-hole of the mount. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     An embodiment of the present invention will now be described by way of example, with reference to the accompanying figures in which; 
       FIG. 1  shows a mount and support according to the present invention, dissembled; 
       FIG. 2  shows the mount and support, assembled; 
       FIG. 3  shows a perspective view of a linear accelerator arm for use in the present invention; 
       FIG. 4  shows a side sectional view of the linear accelerator arm; 
       FIG. 5  shows a perspective view of the linear accelerator arm fitted to the mount; 
       FIG. 6  shows a view from the side of the linear accelerator arm fitted to the mount; 
       FIG. 7  shows a perspective view of the operative elements of linear-accelerator system based on the mount of the present invention; 
       FIG. 8  shows the complete linear-accelerator system ready to treat a patient; 
       FIGS. 9 and 10  show the complete linear-accelerator system treating a patient; 
       FIG. 11  shows a perspective view of the operative elements of a rotational therapy system based on the mount of the present invention; and 
       FIGS. 12 and 13  show the complete rotational therapy system treating a patient. 
   

   DETAILED DESCRIPTION OF THE EMBODIMENTS 
     FIG. 1  shows a stand  10  with a lower edge  12  that can be affixed to a floor or ground surface. The stand  10  rises generally vertically from its lower face  12 , and has a horizontal through-hole whose internal face defines a generally annular ring section  14 , disposed vertically above the lower base  12 . A circular bearing  16  is fitted within the interior annular face of the ring  14 , and supports a mount  18  by way of a corresponding cylindrical bearing surface  20  provided on the mount  18 . The cylindrical bearing surface  20  comprises a tubular section whose exterior face provides the bearing surface, from one end of which is suspended the main body  22  of the mount  18 . This main body  22  consists of a box section body with a circular aperture  24  at the front thereof and a circular aperture  26  at the rear thereof, with substantially flat top and side portions. The interior of the body  22  is generally open, thus allowing a clear passage through the interior of the mount  18  from the front aperture  24  to the rear aperture  26  and through the tubular section  20 . 
   The top face has an aperture  28 , for reasons which will be explained later. The same applies to the two side faces, which have a left aperture  30  and a right aperture  32 . The bottom face includes an aperture  34  which leads into a box section  36  that is suspended beneath the body  22 . The box section  36  is open at the top face to permit communication through the bottom aperture  34 , and is likewise open at a front section  38 . 
     FIG. 3  shows a linear accelerator arm  40  for use in conjunction with the mount shown in  FIGS. 1 and 2 . An exterior casing  42  covers a magnetron, accelerator  44  and associated elements which produce a high energy beam of electrons and deliver that beam to a beam-bending system  46  which conveys the beam to a radiation head  48  carrying the usual collimator set  50 . 
   This arm  40  can be fitted to the upper face of the mount body  22  as shown in  FIGS. 5 and 6 . An opening  52  ( FIG. 4 ) in the linear accelerator casing  42  allows for connections to be made via the aperture  28  to both the linear accelerator  44  and to control lines for the upper parts of the arm  40 . Counterweights  54 ,  56 ,  58  can be attached to the exterior of the box section  36  opposite the linear accelerator arm  40 , so that the composite apparatus remains balanced around the cylindrical bearing surface. 
   The configuration shown in  FIG. 3 , with all necessary elements such as the waveguide and magnetron integrated into the arm to form a complete radiation generation module is, in this example, made possible by the use of a magnetron. As the magnetron is included in the module, the latter can be tested separately, i.e. after it has been manufactured and before it is attached to other parts of the modular system disclosed herein. This allows streamlining of the manufacturing process by revealing any remedial work that is required at an earlier stage of assembly. 
   A flat panel detector  60  can then be fitted within the box section  36 , as shown in  FIG. 7 . This is mounted on an extendable arm  62 , so that the detector can be extended into position through the aperture  38  into a location opposite the radiation head  48 . Likewise, a diagnostic x-ray tube  64  can be mounted on one lateral side of the mount  18  on a suitable extending arm  66 , and a flat panel detector  68  for the diagnostic source  64  can be mounted on a similar extending arm  70  on the opposite lateral side of the mount  18 . The entire apparatus can be enclosed in a suitable casing  72 , as shown in  FIG. 8 . The central through-hole of the mount  18  can be employed to contain cable runs, conduits, controls and output devices for the apparatus, shown generically as  74  in  FIG. 8 . 
   Together with the provision of a suitable patient table  76  this apparatus may be used to treat a patient  78 . As and when required, the MV detector  60  can be extended on the extending arm  62  to acquire portal images, as shown in  FIG. 9 .  FIG. 10  shows that as an alternative, or in addition, the diagnostic x-ray source  64  can be extended on its extendable arm  64  together with the diagnostic detector  78  on its extendable arm  70  so that as the apparatus rotates around the patient on the circular bearing  16 , diagnostic images can be created. These can, if desired, be built up into a computed tomography scan (CT scan). 
     FIG. 11  shows an alternative treatment arrangement. Again, the mount  18  is supported on a cylindrical bearing  16  which is supported on the base  10 . In this case, however, a short therapeutic x-ray source  80  is disposed on the top base of the mount  18  so as to produce a beam passing through the top aperture  28  and into the through-hole of the mount body  22 . A diagnostic x-ray source  82  is fixed to one side of the mount body  22  so as to project a beam of diagnostic x-rays through the central through-hole and to a flat panel detector  84  mounted to the other side of the mount body  22 . A flat panel detector  86  for the therapeutic radiation is mounted within the box section  36 . A beam stop (not shown) can be disposed in the remainder of the box section. 
   The patient table  76  is located so as to support a patient  78  within a central through-hole of the mount body  22 , so that they are in the field of the short therapeutic source  80 . The mount  18  can then rotate around the patient  78  so as to deliver radiation from a multiplicity of angles. Once this is done, diagnostic radiation from the source  82  is captured by the flat panel detector  84  after passing through the patient, therefore creating diagnostic images which can (as before) be assembled to form a computer tomography scan if desired. The short therapeutic source  80  can of course be collimated as desired, for example with a multi-leaf collimator. 
     FIGS. 12 and 13  show an external casing  88  that can be applied to the device, to protect against accidents or injury as the mount  18  rotates. This extends in a toroidal manner around the device and has a tunnel  90  or other form of opening which extends within the through-hole of the mount body  22  to allow the patient  78  to project into the device. Radiation from the source  80  passes through the material of the cover  88  and is incident on a patient within the tunnel. 
   The rotating mount shown in  FIG. 11  will usually enable continuous rotation by the use of a slip ring, as is known for Tomotherapy and other toroidally-configured apparatus that rely on continuous rotation. This allows the arrangement of  FIG. 11  to mimic the operation of such devices notwithstanding the simpler manufacturing process that is required. It should be noted that the modular nature of the example disclosed herein permits the straightforward inclusion of a slip ring into either arrangement, thereby enabling the provision of a continuously rotatable C-arm linac. 
   Accordingly, the present invention provides an adaptable base unit to which can be attached various items of equipment as required to produce the desired radiotherapeutic apparatus. 
   It will of course be understood that many variations may be made to the above-described embodiment without departing from the scope of the present invention.