Abstract:
The invention relates to a radiotherapy assembly comprising a particle emitter with an exit window for a fixed particle stream and a patient support device comprising a patient couch, which can be brought into an irradiation position that is suitable for irradiating a patient in front of the exit window. An X-ray diagnostic device determines or verifies the position of a tumor that is to be irradiated, said device comprising an X-ray source and a detector, which can be displaced in the area around the patient couch that has been placed in the irradiation position. The assembly permits the location of a tumor to be verified in the irradiation position, thus rendering a relocation of the patient unnecessary.

Description:
RELATED APPLICATIONS 
       [0001]    The present application is a continuation of pending U.S. patent application Ser. No. 11/632,676, filed Jan. 17, 2007, the entirety of which is hereby incorporated by reference. 
         [0002]    The present patent document is a continuation of PCT Application Serial Number PCT/EP2005/054665, filed Sep. 19, 2005, designating the United States, which is hereby incorporated by reference. This application also claims the benefit of DE 10 2004 048 216.0, filed Sep. 30, 2004, which is hereby incorporated by reference. 
     
    
     BACKGROUND 
       [0003]    The present embodiments relate to a medical radiotherapy assembly. 
         [0004]    In radiation therapy using heavy ions, tumors are bombarded with accelerated particles. A particle accelerator forms a particle beam using a beam exit that is fixed in space. During the treatment, the patient must be put into an exact, predefined position, so that the tumor is located at the isocenter of the particle beam. Depending on the position of the tumor in the body, different irradiation positions (fields) are provided for the patient. For instance, the patient is positioned in either a horizontal or a sitting position in front of the particle emitter. 
         [0005]    It is therefore necessary in the field of radiation therapy to determine the exact position of the tumor. For this purpose, imaging diagnosis methods are employed. German Patents DE 189 55 213 C2 and DE 189 27 022 C2 or in European Patent Disclosure EP 0 220 501 B1 disclose X-ray diagnostic devices. The tumor position is typically shown on the patient directly using external markings, skin markings, or on immobilizing masks. 
         [0006]    Depending on the type and size of tumor, in therapy planning, the number of individual radiation treatments (fractions) required to securely destroy the tumor is defined. Typically, 20-30 radiation treatments over a period of several weeks are performed per patient. 
         [0007]    Prior to the irradiation, the patient is brought to a radiation room with a beam exit window for the particle beam. The patient is immobilized or fixed on a patient support. The term “patient support” is understood here generally to include a cot or a chair on which the patient is immobilized. In accordance with the markings located on the skin or immobilizing masks, the patient is moved into the fixed isocenter that is marked by lasers, before the radiation therapy is begun. In addition to the beam exit window, a stationary imaging device is also provided in the radiation treatment room. The stationary imaging device can verify the tumor position from anatomical landmarks. After the verification, the patient is moved from his imaging position to an irradiation position. 
         [0008]    Changes in the position of the tumor between the time of diagnosis and the time of each radiation treatment can lead to reduced effectiveness of the radiation therapy. The orientation of the patient into the isocenter based on the markings also involves imprecision. Even if the tumor position is verified immediately before the radiation treatment, exact positioning is difficult because the patient is moved from the imaging position to the irradiation position. 
       SUMMARY 
       [0009]    The present embodiments may obviate one or more of the drawbacks or limitations of related art. For example, in one embodiment, a medical radiotherapy assembly is able to provide efficient and accurate radiation therapy. 
         [0010]    In one embodiment, a radiotherapy assembly includes an exit window for a particle beam. The exit window includes a beam exit that is fixed in space. A patient support device with a patient support that is disposed in front of the exit window can be put in an irradiation position that is suitable for irradiating a patient. 
         [0011]    In one embodiment, the assembly has a diagnostic device or imaging device for determining or verifying the position of a tumor to be irradiated. The imaging device is an X-ray device and includes an X-ray radiation source and an X-ray detector diametrically opposite the radiation source. The imaging device can be moved in space around the patient support that is located in the irradiation position. 
         [0012]    In one embodiment, The X-ray source and the X-ray detector are secured to a common and mechanically rigid support arm. In this embodiment, the X-ray source and X-ray detector are each positioned at the point relative to one another. For the motion in space, only the support arm has to be suitably triggered and moved. Thus, two independent motions in space are not needed, making the triggering and moving simple. 
         [0013]    In one embodiment, the support arm is supported and triggerable in such a way that both an angular motion about the longitudinal axis defined by the particle beam and an orbital motion about an axis perpendicular to the longitudinal axis can be executed. This embodiment is capable of imaging diagnosis for any possible irradiation position of the patient. The two degrees of rotational freedom and the support arm that is open on one side are superimposed so that all the diagnostic positions for verifying the tumor can be assumed, regardless of the position of the patient at the time. 
         [0014]    In one embodiment, the radiotherapy assembly includes a particle emitter that is combined with an imaging device in such a way that the patient, located on the patient support, can be subjected to both imaging and therapy in one and the same position. A determination or verification of the position of the tumor is made possible directly in the irradiation position. The imaging is performed directly before or even during the radiation treatment. In this embodiment, there is no shifting of the patient from the imaging to the radiation treatment. Shifting the patient always has the intrinsic risk of shifting the tumor. In this embodiment, an exact positioning of the tumor in the isocenter of the particle emitter is made possible because the position of the tumor is verified in the irradiation position. The overall radiation therapy is highly efficient. Because the imaging device is freely movable in space, it is unimportant what position the patient is in, whether seated or lying down, while the radiation therapy is performed. 
         [0015]    In one embodiment, a method to be performed with a radiotherapy assembly includes a position verification that is performed to determine the tumor position. The position verification is possible in any arbitrary therapy position of the patient because of a special embodiment of the radiotherapy assembly. For the position verification, the tumor position is determined from two-dimensional projection images. Alternatively, the position verification for determining the tumor position is determined on the basis of three-dimensional slice images. 
         [0016]    In one embodiment, the position verification as well as the actual radiation treatment are both made possible with the patient lying down and with the patient seated and in any suitable therapy position of the patient. In one embodiment, the patient support is or can be modified as a cot for a horizontal irradiation position or as a chair for a seated irradiation position of the patient. In this embodiment, it is possible, given a stationary beam exit, to irradiate the patient in arbitrary irradiation positions. Frontal irradiation is also made possible because of the seated position. This variability dictated by this embodiment makes considerable cost savings possible, compared to previous systems, since a gantry, with the aid of which the angle of radiation of the particle beam is set in a complicated and hence expensive way, can be dispensed with. 
         [0017]    In one embodiment, the equipment of the particle emitter and the imaging device are combined. In the course of a radiation treatment, the position of the tumor is verified or monitored, and the patient&#39;s position is actively monitored. 
         [0018]    In one embodiment, two-dimensional projection images, for instance, are made and the images produced are compared, with the aid of a suitable image evaluation, with previously developed three-dimensional images of the tumor. Changes in the position of the tumor can be reacted to online, or during a given radiation treatment, by shifting the patient under automatic control, to the optimal irradiation position. 
         [0019]    The highly flexible positionability of the diagnostic device makes it possible with one and the same imaging device, that is, one and the same radiation source and radiation detector pair, to produce images of the tumor for various irradiation positions. In comparison to stationary X-ray diagnostic devices, each of which is provided for making images in only one patient position, a pronounced simplification in terms of equipment and a more-economical embodiment are achieved. 
         [0020]    In one embodiment, the X-ray device uses a conventional X-ray device, for instance for producing two-dimensional projection images or also for producing three-dimensional low-contrast images. When producing three-dimensional low-contrast images, the patient is irradiated with a fanned-out X-ray beam, and the signals received by the radiation detector are evaluated to generate a three-dimensional image. This imaging method is also known by the term 3D cone beam reconstruction. 
         [0021]    In one embodiment, the support arm includes C- or U-shaped mechanical load-bearing constructions that are open to one side. The support arm, in arclike fashion, spans the patient support located between the radiation detector and the radiation source. 
         [0022]    In one embodiment, the support arm is supported and triggerable in such a way that for both the angular motion and for the orbital motion, a rotary angle of at least 180° can be executed. Comprehensive image information, for example, for a three-dimensional image production, can be obtained. If a fanned-out X-ray beam is used for a 3D cone beam process, the rotary motion for the angular motion and orbital motion amounts to at least 180°, plus the fan width of the X-ray beam. 
         [0023]    In one embodiment, the support arm is rotatably supported on the particle emitter. The particle emitter and the diagnostic device form a combined unitary structural unit. Because of the structural combination, the relative position between the radiation source and the radiation detector with respect to the isocenter of the particle emitter is exactly defined. 
         [0024]    In one embodiment, the support arm is a multiaxial robot arm, for example, one arm with six axes. Free motion in space is made possible without or virtually without limitations, so that individual requirements can easily be taken into account because of the guidance via a multiaxial robot arm. In both variants, a load-bearing structure of the diagnostic device is located in stationary form in space, and only the support arm is freely movable in space. 
         [0025]    In one embodiment, the patient support is movable in controlled fashion to a predefined irradiation position. The patient can be moved to a desired position after the verification of the tumor position. 
         [0026]    A common control unit is provided. The common control unit controls two devices, namely the diagnostic device and the patient support device, in a way adapted to one another. The patient support with the patient immobilized on it is moved into the required irradiation position based on the isocenter of the particle beam and the tumor position, which is ascertained with the aid of the diagnostic device. In one embodiment, determining the position of the tumor from the X-ray images is done either automatically by suitable automatic image recognition processes or manually by skilled medical personnel who inform the control unit of the position of the tumor via a suitable input device. 
         [0027]    In one embodiment, a plurality of exit windows for the particle beam are provided at predetermined angles relative to the patient&#39;s position. Because the diagnostic device is movable in space around the patient support located in the irradiation position, the same diagnostic device is also suitable for radiation therapy applications involving a plurality of exit windows for the particle beam. In one embodiment, the diagnostic device is used in combination with a plurality of exit windows, disposed at defined angles, for particle beams, each with exit windows that are fixed in space. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0028]      FIG. 1  shows one embodiment of a radiotherapy assembly that includes a rotatably supported X-ray diagnostic device and a C-arch support arm in one irradiation position; 
           [0029]      FIG. 2  shows one embodiment of a radiotherapy assembly that includes a rotatably supported X-ray diagnostic device and a C-arch support arm in one irradiation position; 
           [0030]      FIG. 3  shows one embodiment of a radiotherapy assembly that includes a rotatably supported X-ray diagnostic device and a C-arch support arm in one irradiation position; 
           [0031]      FIG. 4  shows another embodiment of the radiotherapy assembly that includes a support arm secured to a multiaxial robot arm; and 
           [0032]      FIG. 5  shows one embodiment of the radiotherapy assembly that includes a support arm secured to a multiaxial robot arm. 
       
    
    
     DETAILED DESCRIPTION 
       [0033]    Generally, in the drawings, elements that function the same are identified by the same reference numerals. 
         [0034]    The medical radiotherapy assembly includes a particle accelerator for generating a particle beam comprising heavy ions, hereinafter called a particle emitter. The particle emitter includes a barrel  2  and an exit window  4  on the front. When the exit window  4  is at a predefined position, a particle beam  6  emerges during operation. The barrel  2  and the exit window  4  are disposed in stationary fashion in space. In an alternate embodiment (not shown), a plurality of fixed exit windows  4  are disposed in space at defined angles. 
         [0035]    An X-ray diagnostic device  8  includes a support arm  10 A,  10 B, which has an X-ray source  12  and an X-ray detector  14  each disposed at diametrically opposed positions. 
         [0036]    A patient support device  16  includes a patient support  18 , which is movable in controlled fashion via a first multiaxial robotical support arm  20 . The term “patient support”  18 A,  18 B is a device on which a patient  22  is put into a position intended for the radiation therapy. This position can be either a seated or a horizontal position. The patient support  18 A,  18 B may be a cot for a horizontal position of the patient  22  or a chairlike structure for a seated position of the patient  22 . 
         [0037]    In one embodiment, the X-ray diagnostic device  8  and the exit window  4  are combined, such that an X-ray image for determining or verifying the position of a tumor can be made in the treatment position of the patient  22  intended for the radiation therapy. The X-ray diagnostic device  8  is suitable for both two-dimensional projection images and for three-dimensional low-contrast images and is able to generate 3D cone beam images. 
         [0038]    In exemplary embodiments, as shown in the Figures, a fan-shaped X-ray beam  24  produces the 3D cone beam images, or generates three-dimensional images of the tumor to be irradiated. A known method for image generation and image evaluation may be used. To produce 3D X-ray images, the fan-shaped beam  24  is movable by at least 180°, plus the fan angle, around the patient  22 . Regardless of the particular irradiation position of the patient  22 , verification of the tumor can be done with one and the same diagnostic device. The position verification is independent of whether the patient  22  is lying down or in a seated position, that is, whether he is oriented longitudinally to the particle beam  6  or transversely to it. A definitive factor for this variability is the disposition of the X-ray diagnostic device  8  in such a way that it is freely movable in space. 
         [0039]    The support arm  10 A,  10 B is open to one side. In this embodiment, the support arm  10 A,  10 B may include a U-shape or C-shape. The support arm  10 A,  10 B can be moved without problems above the patient and the patient is positioned between the radiation source  12  and the radiation detector  14 . For the rotatability by more than 180° around the patient  22 , the support arm  10 A,  10 B can execute an angular motion around the longitudinal axis defined by the particle beam  6 . As shown in the Figures, the angular motion is indicated by a double arrow  26 . Alternatively, the support arm  10 A,  10 B is also capable of executing an orbital motion about an axis perpendicular to the particle beam  6 . This orbital motion is represented by a further double arrow  28 . 
         [0040]    Once the patient  22  has assumed a defined treatment position, the diagnostic device  8  executes a 180° rotation (plus the fan angle of the X-ray beam) in only one of the two directions of motion. The diagnostic device  8  executes either an angular motion  28  about the longitudinal axis or an orbital motion  28  about a further pivot axis that is perpendicular to the longitudinal axis. The location of this further pivot axis in space is variable and depends on the angular rotary position at the time of the support arm  10 A,  10 B. 
         [0041]    In the exemplary embodiments of  FIGS. 1 through 3 , the support arm  10 A is embodied as a C-arch, which has the radiation source  12  and the detector  14 , respectively, on the ends of its arch. The support arm  10 A, for executing the angular motion  26 , is supported via a rotary ring  30  that extends annularly around the barrel  2 . The support arm  10 A can be rotated about the longitudinal axis defined by the particle beam  6  via the rotary ring  30 . For executing the orbital motion  28 , the support arm  10 A is supported displaceably on the rotary ring  30  itself. For example, the support arm  10 A is guided by a guide rail or by a mesh toothing between the rotary ring  30  and the support arm  10 A. An orbital rotation of 180° can be executed in any angular rotary position. Conversely, an angular rotary motion  26  about at least 180° can be executed in any orbital rotary position. According to these embodiments, rotary motions of about 360° are possible in each case. The rotary motions are limited essentially by the position of the patient support  18 A,  18 B. 
         [0042]    In the exemplary embodiment of  FIG. 1 , the patient  22  is in a horizontal irradiation position, oriented longitudinally to the particle beam  6 , for treatment of a brain tumor. In this embodiment, for 3D image verification of the position of the brain tumor, the support arm  10 A is rotated around the head of the patient  22  by rotation of the rotary ring  30  by at least 180° in the angular direction  26 . 
         [0043]    In the exemplary embodiment shown in  FIG. 2 , the patient  22  is located transversely to the particle beam  6 , in a horizontal position. The support arm  10 A is in a fixed angular position. For X-ray imaging, the support arm  10 A is pivoted by at least 180° in the orbital direction  28  around the torso of the patient  22 . A rotary motion in the angular direction  26  does not take place in this embodiment. 
         [0044]    In the exemplary embodiment shown in  FIG. 3 , the patient  22  is in a seated treatment position. For taking the X-ray image, once again a motion of the support arm  10 A takes place in the orbital direction  28 . 
         [0045]    As shown in  FIGS. 4 and 5 , the support arm  10 B is secured to a second support arm  32 , which has six axes. The second robot arm  32  is secured to the ceiling of a room in this exemplary embodiment. Because of the multiaxial embodiment of the second robot arm  32 , the support arm  10 B can be positioned at arbitrary points in the room that are accessible by the second robot arm  32 . For performing the angular rotary motion  26  and the orbital rotary motion  28 , the second robot arm  32  has a plurality of pivot joints  34 . For recording the X-ray image, an at least 180° rotation is performed, either in the orbital direction  28  or in the angular direction  26 , depending on the particular irradiation position in which the patient  22  is located at the time. 
         [0046]    The X-ray diagnostic device  8 , the patient support device  16 , and optionally the particle accelerator are preferably driven by a common control unit that is adapted to each device. In one embodiment, the patient  22  is put into a preliminary treatment position for the radiation therapy. In this embodiment, the patient  22  is immobilized on the patient support  18 A,  18 B, and the patient support  18 A,  18 B and is then moved by the first robot arm  20  into the desired preliminary treatment position. In this position, the position of the tumor is determined and verified with the aid of the X-ray device  8 . The immobilized patient  22  is moved, automatically and under control, into the optimal irradiation position via the patient support device  8 , so that the tumor is positioned in the isocenter. The correct positioning is verified with the X-ray device  8 . 
         [0047]    The determination of the tumor position is done either automatically or by evaluation by professional medical persons of the images made. After the patient  22  is positioned, the particle beam  6  is generated, and the patient  22  is irradiated. In each of the drawings, the particle beam  6  is shown in dashed lines, in order to indicate that the radiation treatment with the particle beam  6  is completed after the X-ray images have been made. 
         [0048]    With the aid of a control unit and monitoring unit, not shown in further detail here, the patient  22  is preferably automatically moved into the correct treatment position for the radiation treatment. 
         [0049]    Various embodiments described herein can be used alone or in combination with one another. The forgoing detailed description has described only a few of the many possible implementations of the present invention. For this reason, this detailed description is intended by way of illustration, and not by way of limitation. It is only the following claims, including all equivalents that are intended to define the scope of this invention.