Abstract:
A non-invasive medical treatment installation has a therapy C-arm mounted on a base, and defining an isocenter. A therapy apparatus having a focus is mounted at the free end of a carrier arm, that has a fixed end attached to the therapy C-arm. The mounting of the fixed end of the carrier arm to the therapy C-arm allows orbital movement of the carrier arm along the therapy C-arm between two final positions respectively delimited by the opposite ends of the C-arm. The carrier arm is mounted to the therapy C-arm to allow rotation of the carrier arm around a rotational axis, so that when the carrier arm is at either of said final positions, it extends beyond the respective end of the C-arm.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention concerns a system for non-invasive medical treatment of the type wherein a therapy apparatus (such as a shockwave head in the case of a lithotripsy treatment) is moved on an orbit around a patient table or around a patient on this patient table. 
   2. Description of the Prior Art 
   A body region of the patient to be treated in a system of the above type is arranged in the isocenter of the orbit. The focus of the therapy apparatus (in the case of a shockwave head thus the focus of the ultrasonic waves emanating therefrom) is located in the isocenter or in the body region to be treated. A circular arc, known as a C-arm, is generally used for guidance of the therapy apparatus. In the case of a C-arm that is permanently fixed at a base, this C-arm must exhibit an arc length that is at least as large as the desired movement path of the therapy apparatus. The arc length of the C-arm can be shortened if it is supported so that it can be moved orbitally on the base. A therapy apparatus movably guided on a C-arm has the advantage that it can be positioned on different sides of the body of a patient without the patient having to be repositioned on the patient table. A system of this type is normally designed such that the base and further system parts are arranged on one side of the patient table, so the other side of the patient table can remain essentially free in order to allow unhindered access to the patient (such as for anesthesia purposes). If a therapy apparatus should now be brought into position on this side of the patient table, the therapy apparatus itself is less disruptive than the C-arm because the therapy apparatus is positioned relatively close to the patient. If, for example, a shockwave head is positioned in the 0° position (i.e. in the upper table position given vertical alignment of its shockwave axis) for lithotripsy treatment, the C-arm extends into the space above the patient at least up to this angle position. A treating doctor is thereby severely limited in terms of his or her freedom of movement in the region of the doctor&#39;s head. 
   SUMMARY OF THE INVENTION 
   An object of the present invention is to provide a system for non-invasive medical treatment wherein the aforementioned disadvantage is avoided. 
   This object is achieved according to the invention by a therapy system having a carrier arm with a fixed end and a free end mounted on the therapy C-arm, the fixed end of the carrier arm being supported on the therapy C-arm between two end positions predetermined by the arc ends such that the carrier arm with its fixed end can move in an orbit. The carrier arm supports the therapy apparatus on its free end. The carrier arm is furthermore supported on the therapy C-arm such that it can rotate around a rotation axis, so it can be aligned at both end positions such that it extends beyond the respective arc end. The rotatable support of the carrier arm on the therapy C-arm ensures that such a projection beyond the arc end can also be produced in a simple manner at the other end position. 
   The rotation axis of the carrier arm is preferably aligned such that it intersects the focus of the therapy apparatus. It is thereby ensured that, given a rotation of approximately 180° around the rotation axis of the therapy focus, its position is not altered. This position typically lies in the isocenter of a C-arm. The position of the therapy focus is thus altered neither by an orbital movement of the carrier arm nor by a rotation around the rotation axis. 
   In a further preferred embodiment, the therapy apparatus is arranged such that its focus is located in a plane that runs parallel to and removed from the orbital plane of the therapy C-arm. This makes it possible to remove the effective location of the therapy apparatus from the orbital plane of the therapy C-arm and thereby to achieve even more freedom of movement in the region of the therapy C-arm for a person attending the patient. This embodiment is particularly advantageous when, for imaging accompanying a treatment, an x-ray C-arm is arranged coaxial, coplanar and with axial offset relative to the therapy C-arm, the focus of the therapy apparatus coinciding with the isocenter of the x-ray C-arm. In addition to the increased freedom of movement (already mentioned) for medical personnel, this achieves the advantage that the x-ray C-arm can in practice be moved orbitally without hindrance. In an arrangement of x-ray and therapy C-arms in which the orbital planes of both arcs coincide, the orbital movement capability of the x-ray C-arm is significantly limited, for example because x-ray source or x-ray receiver protrude into the movement path of the therapy C-arm. 

   
     DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a base for a therapeutic treatment system in accordance with the invention, on which a therapy C-arm is supported that carries a therapy apparatus, the C-arm being supported so as to be able to move orbitally around an isocenter. 
       FIG. 2  is a perspective view of a portion of the system of  FIG. 1 . 
       FIG. 3  is a further perspective view of a further embodiment of a system in accordance with the present invention, wherein an x-ray C-arm is associated with the therapy C-arm. 
       FIG. 4  shows the system of  FIG. 1 , with the therapy apparatus located in a different position. 
       FIG. 5  shows a portion of the system of  FIG. 4  with the therapy apparatus in a treatment position. 
       FIG. 6  schematically illustrates the therapy C-arm and the x-ray C-arm of the embodiment of  FIG. 4 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The system shown in the Figures has a base  1  on which is fixed a first C-arm that supports a therapy apparatus (for example the shockwave head  2  of a lithotripsy system). The first C-arm (designated in the following as therapy C-arm  3 ) is an annulus segment that can be orbitally moved on an extension arm  4  of the base frame  1  around its middle point or around its isocenter  5 , which is indicated in  FIG. 1  by the double arrow  6 . A sled  7  is supported on the therapy C-arm  3  such that it can move orbitally (thus corresponding to double arrow  6 ). A carrier arm  9  is attached with its fixed end  10  on a side  8  of the sled  7  facing the isocenter  5 . The free end  12  of the carrier arm  9  carries the shockwave head  2 . Due to the orbital movement capability of the therapy C-arm  3  and the sled  7 , the shockwave head  2  can be positioned in various angle positions relative to the isocenter  5  or to a patient table  15 . The radial separation of the shockwave head  2  from the isocenter  5  is selected such that the focus  13  of a shockwave cone  14  emitted from the shockwave head  2  lies on a central axis  18  extending through the isocenter  5 . The shockwave head  2  can, for example, be arranged such that the shockwave axis  16  thereof proceeds in the orbital plane  17  spanned by the therapy C-arm  3 . 
   As can be seen from  FIG. 1  and in particular from  FIG. 2 , the carrier arm  9  is designed or aligned such that, in its upper end position ( FIG. 2 ), it extends beyond the upper arc end  19  in the arc circumference direction, viewed in the direction of the central axis  18  situated perpendicular to the orbital plane  17  and extending through the isocenter  5 . An unhindered accessible space  20  in the head region of a person attending a patient during the treatment thus exists above the shockwave head  2 . If the carrier arm (likewise seen in the projection of  FIG. 2 ) were aligned approximately in the direction of the shockwave axis  16 , thus radially, the therapy C-arm  3  would have to be longer by approximately the arc segment  22  or would have to be orbitally moved further by a corresponding length, whereby it would limit the freedom of movement of an attending person in the space  20 . 
   So that both the therapy C-arm  3  and the sled  7  of the carrier arm  9  also overhang the lower arc end  19 ′ in the arc circumference direction in the lower end position, the carrier arm  9  is supported on the sled  7  such that it can rotate around a rotation axis  23 . It would now be possible for not only a single rotation axis to be present, but also for the shockwave head  2  also to exhibit a degree of freedom relative to the carrier arm  9 . The purpose of such a movement capability would be to bring the shockwave head  2  back into a position in which its focus  13  again comes to lie on the central axis  18  (for example coincides with the isocenter  5  of the therapy C-arm  3 ) after cycling an orbital movement path. Such multiple movement possibilities or articulation points, however, form error sources with regard to an exact alignment of the shockwave head  2  as a result of tolerances that can never be entirely precluded given parts that are movably connected with one another. In the described exemplary embodiments, the shockwave head  2  is therefore rigidly connected with the carrier arm  9 , which is likewise rigidly fashioned. The rotation of the carrier arm  9  ensues around a single axis, namely the rotation axis  23 . Given a rotation of 180° around this axis, the carrier arm (like the shockwave head) is located in a mirror-inverted alignment relative to the previous position, with the rotation axis  23  forming the mirror axis. For x-ray-supported observation of, for instance, a lithotripsy treatment, the therapy C-arm can be provided with an x-ray C-arm coaxial therewith, having an x-ray source (not shown) and an x-ray receiver  30  without or with axial offset. In the first case, the orbital planes and the isocenters of both C-arms coincide. The rotation axis  23  of the C-arm  9  proceeds in the common orbital plane of the C-arms and extends through their common isocenter. The shockwave head  2  thus can be aligned such that its shockwave axis  16  proceeds in the common orbital plane. Given a rotation around the rotation axis  23  by 180°, upon transition from one end position into the other the shockwave head  2  again adopts a position in which its shockwave axis  16  runs in the orbital plane  17  of the therapy C-arm  3 . The monitoring with the x-ray system can then ensue “inline” in each angle position, i.e. in the direction of the shockwave axis  16 . In the second case shown in the figures, the x-ray C-arm  24  is arranged with axial separation from the therapy C-arm  3 . Its isocenter  25 , like the isocenter  5  of the therapy C-arm  3 , lies on the central axis  18 . As can be seen from  FIG. 3  and  FIG. 6 , the carrier arm  9  extends laterally out of the orbital plane  17 . The shockwave head  2  fixed at the free end  12  of the carrier arm  9  is then arranged in the region of the orbital plane  26  of the x-ray C-arm  24 , with its focus  13  located in its isocenter  25 . The shockwave head  2  can be aligned such that its shockwave axis  16  proceeds in the orbital plane  26  of the x-ray C-arm  24  in one angle position per side. However, this alignment changes given a rotation around the rotation axis  23 , meaning that the shockwave axis  16  is tilted out of the orbital plane  26 , but, in accordance with the invention, the common isocenter is retained. 
   The carrier arm  9  has a first longitudinal segment  27  with a fixed end  10  and a second longitudinal segment  28  with a free end  12 . The longitudinal segment  27  is born on the sled  7  such that it can rotate. The rotation axis  23  (that is identical with the center longitudinal axis  29  of the longitudinal segment  27 ) pierces the orbital plane  17  of the therapy C-arm  3  with its one end and intersects the isocenter  25  of the x-ray C-arm  24 . Given an orbital shift of the sled  7  on the therapy C-arm  3 , the rotation axis  23  sweeps over the plane of a conical segment whose base surface is formed by the orbital plane  17  of the therapy C-arm and whose tip is formed by the isocenter  25  of the x-ray C-arm  24 . The side  8  of the sled  7  from which the longitudinal section  26  projects proceeds at a right angle to the rotation axis  23 . The second longitudinal segment  28  is fixed at an angle on the first longitudinal segment  27 . Its center longitudinal axis  29  thereby forms an acute angle α ( FIG. 2 ) with the rotation axis  23  in the projection on the orbital plane  17  and an acute angle β ( FIG. 6 ) in the projection on a plane spanning from the examination axis  23  and the central axis  18 . When, starting from the upper table position of the  FIGS. 1-3 , the shockwave head  2  should be moved into an under-table position ( FIGS. 4-6 ), perhaps for treatment of a left or right kidney, two symmetrical operations are necessary, namely rotation by up to 180° around the rotation axis  23  and an orbital shift of the sled  7 . Although both movement procedures can proceed simultaneously, they are described in succession for better comprehensibility. Starting from the situation in  FIG. 2 , if one initially begins with a rotation of 180° around the rotation axis  23  the shockwave head  2  subsequently, approximately adopts the position shown with dashed lines. As can be seen from  FIG. 2 , this corresponds to a rotation around the central axis  18 . The focus  13  persists in the isocenter  25  given the rotation. The shockwave axis  16  thereby sweeps through a conical segment whose tip is the isocenter  25 . Starting from the position shown in the dashed lines, an orbital shift by approximately 50° (angle γ) is necessary if the shockwave head  2  should, for instance, be aligned in the +40° position, and an orbital shift by, for instance, 130° (angle γ′) is necessary for an alignment in the −40° position. In contrast to this, an orbital movement path of the sled  7  (likewise starting from the upper table position) of approximately 240° would be required given an approximately radially-aligned carrier arm extending in the direction of the shockwave axis  16 . A therapy C-arm  3  with an arc length of more than 120° would be necessary for this. In contrast to this, given an inventive embodiment of the carrier arm  9  the therapy C-arm  3  can be shorted by, for instance, a piece corresponding to the arc segment  22 . 
   Although modifications and changes may be suggested by those skilled in the art, it is the invention of the inventors to embody within the patent warranted heron all changes and modifications as reasonably and properly come within the scope of their contribution to the art.