Abstract:
An X-ray lens arrangement for forming a radiation pattern as a focal track is disclosed. The pattern comprises at least one 3-dimensional focal track of radiation. The aforesaid lens arrangement has a main axis passing through intensity weighted centroids of the X-ray source and the pattern. The lens arrangement includes at least one reflecting surface of continuously varying Rowland arcs. Each point belonging to the focal track is linked to each elemental point composing an emitting surface of said source by a corresponding Rowland arc.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to an X-ray lens and, more specifically, to an X-ray lens arrangement configured for focusing a radiation from an X-ray source into a curved radiation pattern in a volume of radiotherapy treatment. 
       BACKGROUND OF THE INVENTION 
       [0002]    According to conventional radiation therapy, a radiation beam is directed towards a tumor located within a patient&#39;s body. The radiation beam delivers a predetermined dose of therapeutic radiation to the tumor according to an established therapy plan. The delivered radiation kills tumor cells by causing ionizations within the cells. In this regard, radiation therapy systems are designed to maximize radiation delivered to the tumor while minimizing radiation delivered to healthy tissue. 
         [0003]    U.S. Pat. No. 6,389,100 discloses a modular X-ray lens system for use in directing X-rays comprising a radiation source which generates X-rays and a lens system which directs the X-ray beam. The X-ray lens system is configured to focus X-rays to a focal point and vary the intensity of said focal point. 
         [0004]    U.S. Pat. No. 7,068,754 discloses an X-ray apparatus including a ring anode to emit radiation, and a conical monochromator to monochromatize the emitted radiation. An outer diameter of the ring anode is greater than an outer diameter of a base of the monochromator. 
       SUMMARY OF THE INVENTION 
       [0005]    It is hence one object of the invention to disclose an X-ray lens arrangement for forming a radiation pattern as a focal track. The lens arrangement is longitudinally arranged for Bragg X-ray diffraction of the X-ray. 
         [0006]    It is a core purpose of the invention to provide the radiation pattern which is a three-dimensional curve. 
         [0007]    It is a further core purpose of the invention to provide the pattern configured as at least one three-dimensional focal track of radiation. The lens arrangement has a main axis passing through intensity weighted centroids of the X-ray source and the pattern. The arrangement comprises at least one reflecting surface of the lens of continuously varying Rowland arcs. Each point belonging to the focal track is linked to an elemental point composing an emitting surface of the source by a corresponding Rowland arc. 
         [0008]    Another object of this disclosure is to disclose the abovementioned invention wherein the source is a point source. The lens arrangement has a main axis passing through the point source and centroid of the pattern. Each point of the focal track is linked to the source by a corresponding Rowland arc. 
         [0009]    A further object of this disclosure is to disclose the abovementioned invention wherein the reflecting surface is continuously defined by a Rowland arc of a constant radius. 
         [0010]    A further object of this disclosure is to disclose the abovementioned invention wherein the reflecting surface is defined by continuously varying Rowland arcs of correspondingly varying radii. 
         [0011]    A further object of this disclosure is to disclose the abovementioned invention wherein the focal track has a three-dimensional configuration. 
         [0012]    A further object of this disclosure is to disclose the abovementioned invention wherein the focal track is in a plane whose normal is tilted relative to the main axis. 
         [0013]    A further object of this disclosure is to disclose the abovementioned invention wherein a shape of at least one of the tracks is selected from the group consisting of an orthogon, a square, a triangle, a parallelogram, a rhomb, a polygon, an oval, and any combination thereof, where the shape can be defined longitudinally or transversely or in any angle relative to the main axis. 
         [0014]    A further object of this disclosure is to disclose the abovementioned invention wherein the curved track is closed or open. 
         [0015]    A further object of this disclosure is to disclose the abovementioned invention wherein the pattern comprises a plurality of focal tracks. 
         [0016]    A further object of this disclosure is to disclose the abovementioned invention wherein the pattern comprises a plurality of focal tracks, where at least two of the said focal tracks are reflected from reflecting surfaces comprising the same crystallographic planes. 
         [0017]    A further object of this disclosure is to disclose the abovementioned invention wherein the focal pattern comprises a plurality of three-dimensional focal tracks of non-symmetrical geometry. 
         [0018]    A further object of this disclosure is to disclose the abovementioned invention wherein the focal pattern comprises a plurality of three-dimensional focal tracks of symmetrical geometry. 
         [0019]    A further object of this disclosure is to disclose the abovementioned invention wherein the focal pattern comprises a plurality of coplanar focal tracks. 
         [0020]    A further object of this disclosure is to disclose the abovementioned invention wherein the focal pattern comprises a plurality of noncoplanar focal tracks. 
         [0021]    A further object of this disclosure is to disclose the abovementioned invention wherein the focal pattern comprises a plurality of focal tracks being in planes intersecting at lines passing through the main axis. 
         [0022]    A further object of this disclosure is to disclose the abovementioned invention wherein the focal pattern comprises a plurality of focal tracks being in planes intersecting at lines not passing through the main axis. 
         [0023]    A further object of this disclosure is to disclose the abovementioned invention wherein the focal pattern comprises a plurality of three-dimensional focal tracks longitudinally displaced therebetween. 
         [0024]    A further object of this disclosure is to disclose the abovementioned invention wherein the focal pattern comprises a plurality of three-dimensional transversally shifted focal tracks. 
         [0025]    A further object of this disclosure is to disclose the abovementioned invention wherein the focal pattern comprises a plurality of three-dimensional longitudinally shifted focal tracks. 
         [0026]    A further object of this disclosure is to disclose the abovementioned invention wherein the plurality of curved tracks is concentric. 
         [0027]    A further object of this disclosure is to disclose the abovementioned invention wherein the plurality of curved tracks is non-concentric. 
         [0028]    A further object of this disclosure is to disclose an X-ray reflective lens arrangement for forming a radiation pattern in a focal region. The lens arrangement is longitudinally arranged for Bragg X-ray diffraction of the X-ray. 
         [0029]    A further object of this disclosure is to disclose the abovementioned invention wherein the lens assembly comprises of an inverted image assembly. 
         [0030]    It is a core purpose of the invention to provide the lens arrangement having a main axis passing through intensity weighted centroids of the X-Ray source and the pattern. The lens arrangement comprises at least one pair of oppositely oriented lenses placed along the main optical axis. Reflective surfaces of the first and second lens are continuously defined by Rowland arcs. The first lens is configured to focus a radiation from the X-ray source into an intermediate radiation pattern; the second lens is configured to further reflect the radiation of the intermediate pattern to form an output radiation pattern within the focal region. 
         [0031]    A further object of this disclosure is to disclose the abovementioned invention wherein the X-ray source is point-like. Reflective surfaces of the first and second lens are defined by continuously varying Rowland arcs. 
         [0032]    A further object of this disclosure is to disclose the abovementioned invention wherein the reflecting surfaces of oppositely oriented lenses are continuously defined by a Rowland arc of a constant radius. 
         [0033]    A further object of this disclosure is to disclose the abovementioned invention wherein the reflecting surfaces of oppositely oriented lenses are defined by continuously varying Rowland arcs of correspondingly varying radii. 
         [0034]    A further object of this disclosure is to disclose the abovementioned invention wherein the focal track formed by the double reflection arrangement has a three-dimensional configuration. 
         [0035]    A further object of this disclosure is to disclose the abovementioned invention wherein the focal track formed by the double reflection arrangement is in a plane whose normal is tilted relative to the main axis. 
         [0036]    A further object of this disclosure is to disclose the abovementioned invention wherein a shape of at least one of the track formed by the double reflection arrangement is selected from the group consisting of an orthogon, a square, a triangle, a parallelogram, a rhomb, a polygon, an oval, and any combination thereof, where the shape can be defined longitudinally or transversely or in any angle relative to the main axis. 
         [0037]    A further object of this disclosure is to disclose the abovementioned invention wherein the curved track formed by the double reflection arrangement is closed or open. 
         [0038]    A further object of this disclosure is to disclose the abovementioned invention wherein the pattern formed by the double reflection arrangement comprises a plurality of focal tracks. 
         [0039]    A further object of this disclosure is to disclose the abovementioned invention wherein the pattern formed by the double reflection arrangement comprises a plurality of focal tracks, wherein the pattern comprises a plurality of focal tracks, where at least two of the said focal tracks are reflected from reflecting surfaces comprising the same crystallographic planes. 
         [0040]    A further object of this disclosure is to disclose the abovementioned invention wherein the focal pattern formed by the double reflection arrangement comprises a plurality of three-dimensional focal tracks of non-symmetrical geometry. 
         [0041]    A further object of this disclosure is to disclose the abovementioned invention wherein the focal pattern formed by the double reflection arrangement comprises a plurality of three-dimensional focal tracks of symmetrical geometry. 
         [0042]    A further object of this disclosure is to disclose the abovementioned invention wherein the focal pattern formed by the double reflection arrangement comprises a plurality of coplanar focal tracks. 
         [0043]    A further object of this disclosure is to disclose the abovementioned invention wherein the focal pattern formed by the double reflection arrangement comprises a plurality of noncoplanar focal tracks. 
         [0044]    A further object of this disclosure is to disclose the abovementioned invention wherein the focal pattern formed by the double reflection arrangement comprises a plurality of focal tracks being in planes intersecting at lines passing through the main axis. 
         [0045]    A further object of this disclosure is to disclose the abovementioned invention wherein the focal pattern formed by the double reflection arrangement comprises a plurality of focal tracks being in planes intersecting at lines not passing through the main axis. 
         [0046]    A further object of this disclosure is to disclose the abovementioned invention wherein the focal pattern formed by the double reflection arrangement comprises a plurality of three-dimensional focal tracks are longitudinally displaced therebetween. 
         [0047]    A further object of this disclosure is to disclose the abovementioned invention wherein the focal pattern formed by the double reflection arrangement comprises a plurality of three-dimensional transversally shifted focal tracks. 
         [0048]    A further object of this disclosure is to disclose the abovementioned invention wherein the focal pattern formed by the double reflection arrangement comprises a plurality of three-dimensional longitudinally shifted focal tracks. 
         [0049]    A further object of this disclosure is to disclose the abovementioned invention wherein the plurality of curved tracks formed by the double reflection arrangement is concentric. 
         [0050]    A further object of this disclosure is to disclose the abovementioned invention wherein the plurality of curved tracks formed by the double reflection arrangement is non-concentric. 
         [0051]    A further object of this disclosure is to disclose the abovementioned invention wherein the lens assembly comprises an inverted image assembly. 
         [0052]    A further object of this disclosure is to disclose a method of forming an X-ray radiation pattern in a focal region such that the radiation pattern is configured as a curved track. 
         [0053]    A further object of this disclosure is to disclose a method of forming an X-ray radiation pattern in a focal region. The aforesaid method comprises the steps of: (a) providing an X-ray source; (b) providing a reflective lens arrangement longitudinally arranged for Bragg X-ray diffraction of the X-rays; and (c) forming the radiation pattern in the focal region. 
         [0054]    It is a further core purpose of the invention to provide the pattern formed as at least one three-dimensional curved focal shape of radiation. The step of forming the radiation pattern is performed by the lens arrangement having a main axis passing through intensity weighted centroids of an X-Ray source and the focal track. The arrangement comprises at least one reflecting surface of the lens of continuously varying Rowland arcs; each point belonging to the point ensemble of the focal track is linked to an elemental point of a source emitting surface by a corresponding Rowland arc. 
         [0055]    A further object of this disclosure is to disclose the abovementioned invention wherein the step of forming the radiation pattern is performed by the source being point-like. The lens arrangement has a main axis passing through the point source and centroid of the pattern. Each point of the focal track is linked to the source by a corresponding Rowland arc. 
         [0056]    A further object of this disclosure is to disclose the abovementioned invention wherein the lens assembly comprises at least one lens arrangement nested within said assembly. 
         [0057]    A further object of this disclosure is to disclose a method of forming a radiation pattern in a focal region. The aforesaid method comprises the steps of: (a) providing an X-ray source; (b) providing a reflective lens arrangement longitudinally arranged for Bragg X-ray diffraction of the X-rays; (c) forming the radiation pattern in the focal region. 
         [0058]    It is a further core purpose of the invention to provide the step of forming the radiation pattern performed by the lens arrangement having a main axis passing through the intensity weighted centroids of the X-ray source and the pattern. The arrangement comprises at least one pair of oppositely oriented lenses which are placed along the main optical axis forming a double lens setup. Reflective surfaces of the first and second lenses are defined by continuously varying Rowland arcs connecting each elemental point of the source to a corresponding elemental point of the focal track. The first lens is configured to focus radiation from the X-ray source into an intermediate radiation pattern. The second lens is configured to further reflect the radiation of the intermediate pattern to the output radiation pattern within the focal region. 
         [0059]    A further object of this disclosure is to disclose the abovementioned invention wherein the step forming of the radiation pattern comprises forming an inverted image. 
         [0060]    A further object of this disclosure is to disclose the abovementioned invention wherein the step of forming the radiation pattern is performed by a point-like source. Reflective surfaces of the first and second lenses are defined by continuously varying Rowland arcs. 
         [0061]    A further object of this disclosure is to disclose the abovementioned invention wherein a lens design comprises at least one ring holding Bragg reflector single crystals. Each ring contains Bragg reflectors cut and polished to the same crystallographic plane with more than one ring, having Bragg reflector single crystals cut and polished to the same crystallographic plane. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0062]    In order to understand the invention and to see how it may be implemented in practice, a plurality of embodiments is now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which 
           [0063]      FIG. 1  is a schematic partial longitudinal cross sectional view of a crystal element with schematic reflection planes of an X-ray lens; 
           [0064]      FIG. 2  is a two-dimensional diagram of the Johansson scheme; 
           [0065]      FIG. 3  is a schematic presentation of the elemental reflective lens; 
           [0066]      FIG. 4  is a general schematic view of the lens arrangement; 
           [0067]      FIGS. 5 and 6  are schematic views of the exemplary embodiments of the lens arrangement; 
           [0068]      FIGS. 7 to 9  are schematic views of the exemplary radiation patterns; 
           [0069]      FIG. 10  is a schematic view of an exemplary embodiment of an open lens arrangement; 
           [0070]      FIG. 11  is a schematic view of the lens arrangement comprising the plurality of reflective surfaces; 
           [0071]      FIG. 12  is a schematic view of the lens arrangement with the double lens setup; 
           [0072]      FIGS. 13 and 14  are schematic views of the lens arrangement with the double lens wide convergence angle comprising the plurality of reflective surfaces; 
           [0073]      FIG. 15  is a schematic view of an exemplary combined lens arrangement comprising the single lens nested within a double lens arrangement. 
           [0074]      FIG. 16  is a schematic view of an exemplary lens comprising an inverted image assembly and 
           [0075]      FIG. 17  is a schematic view of an exemplary double lens wide convergence angle comprising an inverted image assembly. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0076]    The following description is provided, alongside all chapters of the present invention, so as to enable any person skilled in the art to make use of the aforesaid invention, and sets forth the best modes contemplated by the inventor of carrying out this invention. Various modifications, however, are adapted to remain apparent to those skilled in the art, since the generic principles of the present invention have been defined specifically to provide an X-ray reflective lens arrangement for forming an intensity pattern in a focal region and methods of using the same. 
         [0077]    The term “elemental” hereinafter refers to infinitely small portion of a physical entity. 
         [0078]    The term “focal track” hereinafter refers to an ordered ensemble of elemental focal points created by a reflecting surface of an X-ray lens. 
         [0079]    The term “intensity weighted centroid of the X-ray source” hereinafter refers to a point defined by a vector  r   sc , 
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         [0080]    The term “intensity weighted centroid of the focal pattern” hereinafter refers to a point defined by a vector {dot over (r)} fc   
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         [0081]    I focus  (x,y,z) is a spatial distribution of radiation intensity in the focal region, and I source (x,y,z,) is the spatial distribution of source intensity at the source space. It should be appreciated that the radiation pattern has a three-dimensional shape. 
         [0082]    Referring to the medical use of the X-ray system for tumor treatment, the known therapeutic devices comprising focusing elements are characterized by concentration of X-ray radiation into a sharp focal spot. It should be emphasized that uniform X-ray exposure of a target volume is a desirable condition of successful therapy or surgery because the optimal effect is achieved when all target tissue is exposed to a uniform dose. Thus, there is a long-felt and unmet need to provide a therapeutic device for X-ray treatment of tumors adapted for forming substantially uniform X-ray intensity within the target volume. 
         [0083]    Reference is now made to  FIG. 1 , illustrating a simple Bragg reflector utilizing the principles of Bragg reflection. X-ray radiation  4  of wavelength λ is incident on a crystal having lattice planes  2  of plane spacing d. Narrow band or generally monochromatic radiation  6  is then reflected according to Bragg&#39;s Law. Bragg structures only reflect radiation when Bragg&#39;s equation is satisfied: 
         [0000]        nλ= 2 d  sin θ B ,  (1)
 
         [0000]    where n is the reflection order, λ is the incident radiation wavelength, d is the lattice plane spacing, and θ B  is the Bragg angle. 
         [0084]    Reference is now made to  FIG. 2 , presenting a two-dimensional longitudinal cut of the Johansson scheme. A Johansson bent and machined crystal  10  is used to reflect and focus X-rays. The Johansson bent and machined crystal  10  reflects X-rays according to Bragg&#39;s law. The Johansson crystal  10  is made by bending and grinding a crystal into a barrel shaped surface with a longitudinal bending radius 2R, and then the reflection surface  14  is machined to a cylindrical surface with longitudinal radius R. In a special symmetrical case, the angles of incidence of rays  15  generated by the X-ray source S and angles of reflection of rays  17  converging into the point F, are equal. 
         [0085]    The transversal curvature radius of the machined surface at a midpoint between the source and the focal point r s  is given by 
         [0000]        r   s   =L  tan θ B ,  (2)
 
         [0000]    L is half of the distance from the source to the focal point. 
         [0086]    The Rowland radius R is given by the following expression 
         [0000]    
       
         
           
             
               
                 
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         [0087]    Reference is now made to  FIG. 3 , elucidating a subject matter of the current invention. An elemental point  11  is a part of the image of an elemental X-ray source point  9  in source space X S Y S  formed by an elemental portion  60  of reflective lens which lies in a Rowland arc  70  subtended by a chord  25 . Lines  40  and  50  refer to rays emitted by the X-ray source elemental point  9  and reflected from the lens portion  60 , respectively. An axis  18  is a main axis of the entire lens. The chord  25  is the optical axis of the narrow reflective lens portion  60 . The aforesaid point  11  is at location r im  on the X I Y I  plane of the image space. 
         [0088]    The elemental point source  9  makes an angle φ S  relative to the X S  axis in source space. 
         [0089]    The elemental point  11  makes an angle φ I  relative to the X I  axis in image space, wherein φ S  and φ I  are generally not the same, thus in general the image point  11  can be rotated relative to the source point  9 . 
         [0090]    Reference is now made to  FIG. 4 , presenting a lens arrangement  100  continuously defined by an ensemble of elemental arcs  60  being rotated around the main axis  18 . The lens arrangement  100  focuses radiation emitted by the X-ray source  12  into a curved radiation pattern  31 . It should be emphasized that the curved pattern of radiation pattern  31  is an ensemble of elemental points  11  (not shown) created by the plurality of elemental arcs  60  integrally forming the reflective surface  100 . 
         [0091]    The main axis  18  is defined by two points which are: (1) the intensity weighted centroid C 1  of the X-ray source, and (2) a centroid C 2  of the linear radiation pattern  30 . The centroids are intensity weighted average points of the source and the radiation patter  31 . 
         [0092]    Reference is now made to  FIGS. 5 and 6 , presenting exemplary embodiments of the current invention. Specifically, a lens arrangement  100   a  is configured to provide an elliptic radiation pattern  30   a  while a lens arrangement  100   b  focuses radiation from the X-ray source into an orthogon  30   b  with rounded angles. The designation P refers to a point source. 
         [0093]    Reference is now made to  FIGS. 7 to 9 , presenting exemplary radiation patterns focused by optional embodiments of the current invention. Simple closed curves radiation patterns are shown in  FIG. 7 . The radiation patterns comprising two curved radiation tracks (one inside another) are depicted in  FIG. 8  (concentric radiation patterns) and  FIG. 9  (non-concentric radiation patterns). 
         [0094]    Reference is now made to  FIG. 10 , presenting an alternative embodiment of the current invention. A lens arrangement  100   c  is portioned into two parts, which are configured to provide the X-ray radiation into same curved radiation pattern  30   c.    
         [0095]    Reference is now made to  FIG. 11 , presenting a cross-sectional schematic view of a lens arrangement of the current invention which comprises a plurality of reflective surfaces (for example, three surfaces  61 ,  62  and  63 ). The aforesaid tracks are formed by revolution of Rowland arcs  71 ,  72  and  73  around the main axis  18 , and its elemental image are defined as intersection chords  26 ,  27  and  28  with the corresponding arcs  71 ,  72  and  73 , respectively. The reflective surface  61 ,  62  and  63  reflect the radiation emitted by the point source P to ring-like radiation patterns  32 ,  33  and  34 , respectively. The chords  26 ,  27  and  28  extend from the point source P, and are tilted in this example to the main axis  18  of the lens arrangement. Thus, at output of the lens arrangement, a resulting radiation pattern comprising a plurality of the ring-like radiation patterns  32 ,  33  and  34  is provided. The aforesaid patterns are distributed over the main axis  18 . 
         [0096]    Reference is now made to  FIG. 12 , presenting a cross-sectional schematic view of a double reflection lens arrangement. The lens arrangement comprises a pair of oppositely directed reflective surfaces  60   d  and  60   e  residing on the Rowland arcs  70   d  and  70   e  which are subtended by chords  25   d  and  25   e , respectively. Specifically, the reflective surface  60   d  provides a ring-like radiation pattern  31   a . Then, the reflective surface  60   e  further reflects the radiation of the pattern  31   a  into a point pattern  30   d . A significant advantage of the depicted double reflection lens arrangement is in providing a wide-angle convergent beam essentially to a surface region of a patient&#39;s body without extensive damage to surrounding tissues and the use of low order high reflective crystallographic planes for more than one reflective ring. The wide angle of the beam convergence results in very quick drop in radiation in a space behind the focus point  30   d . Thus, the proposed lens arrangement can be effectively used for X-ray therapy of surface tumors. It also enables having a relatively large lens for higher solid angle of radiation collection. 
         [0097]    Reference is now made to  FIG. 13 , presenting a cross-sectional schematic view of a lens arrangement comprising two pluralities of reflective surfaces (for example, two surfaces in each plurality). Radiation from the point source P is focused by reflecting surfaces  60   g  and  60   f  into ring-like radiation patterns  31   f  and  31   g , respectively. Then, the aforesaid radiation from patterns  31   f  and  31   g  are further reflected by surfaces  60   h  and  60   i  into a point radiation pattern  30   f . The Rowland arcs  70   f ,  70   g ,  70   h  and  70   i  are subtended by chords  25   f ,  25   g ,  25   h  and  25   i , respectively. 
         [0098]    Reference is now made to  FIG. 14 , presenting a cross-sectional schematic view of an alternative embodiment of the current invention. The lens arrangement provides an output radiation pattern comprising a point focal spot  30   n  and at least one ring-like pattern  30   m . Radiation from the point source P is focused by reflecting surfaces  60   k  and  60   l  into ring-like radiation patterns  31   k  and  31   l , respectively. Then, the aforesaid radiation from patterns  31   k  and  31   l  are further reflected by surfaces  60   m  and  60   n  into a ring-like pattern  30   m  and a point radiation pattern  30   n , respectively. The Rowland arcs  70   k ,  70   l ,  70   m  and  70   n  are subtended by chords  25   k ,  25   l ,  25   m  and  25   n , respectively. 
         [0099]    Reference is now made to  FIG. 15 , presenting an exemplary combined lens arrangement comprising at least one single-reflection lens and at least one double reflection lens assembly. Specifically, the combined arrangement comprises of a single lens  60   r  and a double reflection lens arrangement  60   o - 60   p . Each component (single and double lens arrangements) can be replaced with a plurality of similar elements. In addition, each element can be configured for focusing point or non-point source into any focal point or focal track. 
         [0100]    One core purpose of the proposed invention is to describe a lens array design for providing higher efficiency in transmitting the radiation from the x-ray tube to the focul track. For example, the known technical solutions comprise a multiplicity of rings containing Bragg reflector single crystals. However, the present invention, concentrates the radiation within the targeted volume and different rings required crystals cut in different crystallographic planes. However, different crystallographic planes do not have the same reflectivities. Therefore some rings&#39; crystals have higher efficiency than others. The present invention overcoms this limitation and allows the higher efficiency crystal orientations to be used in multiple rings. The proposed technical solution significantly improves the overall efficiency of a lens array and provides more efficient lens array designs which can reduce exposure times or reduce lens complexity for equivalent exposure times. 
         [0101]    Reference is now made to  FIG. 16 , presenting an exemplary lens comprising an inverted image assembly. The lens arrangement is designed so that each of the elemental image points  11   l  and  11   u  belongs to opposite elemental lenses. The aforesaid points called inverted points are located in the same plane defined by their Rowland arcs. For example, the inverted points  11   l  and  11   u  are opposite to each other on the ring focal track  30   s  relative to the elemental surface  60   su  and  60   sl  which produced them. 
         [0102]    In the drawing, the lower and upper drawn cuts of the elements in the drawings are labeled separately. Lens upper surface is labeled  60   su  and the lower part in the drawing is labeled  60   sl . The same applies to the Rowland arcs,  70   su  for upper drawing and  70   sl  for the lower drawing and also for the cords suspending the Rowland arcs  25   su  and  25   sl  and the elemental image points  11   u  and  11   l  connected to the X-rays shown as being a part of the ring  30   w.    
         [0103]    It should be emphasized that the two points  11   u  and  11   l  lay oppositely with respect to the symmetry line  18  that passes between them in their mutual plane containing the two inverted points. 
         [0104]    Reference is now made to  FIG. 17  presenting double lens wide convergence angle comprising an inverted image assembly. An approach similar to  FIG. 16  is a double lens wide convergence angle setup, comprising an inverted image assembly applied also to double reflection assembly. The second reflector  60   wu  and  60   pl  flips the inverted points  11   u  and  11   l  on their mutual plane. This type of assembly hereinafter refers will be referred to as “inverted image assembly” 
         [0105]    The advantages of the present design solution are the following. An inverted image assembly causes the intersection of rays from the inverted sides of each plane containing the inverted points. The area of intersection can be seen as  80   s  in a single reflection assembly of  FIGS. 16 and 80   u  in the double reflection assembly of  FIG. 17 . Summing up the X-ray radiation from the entire surface of the lens forms a secondary concentration around the symmetry line that results in a somewhat higher dose along the symmetry line. 
         [0106]    Concerning the ordinary non-inverted design solutions, the overlapping areas where secondary concentration of X-ray radiation occurs, are located behind the target volume of treatment. This is relatively distant from the location where the radiation has passed the volume of treatment. Thus the radiation damage effect is much weaker due to attenuation of the beam and divergence angle of the X-ray beam. 
         [0107]    The strength of the effect depends on the convergence angle and the width of the reflecting surface. These parameters are controllable by means of changing design parameters. This approach is especially effective in the double reflection assembly where the overlapping area is close to the treated volume. This can serve as part of the treatment plan improving the capability and control of the treated volume. The embodiments depicted in  FIGS. 16 and 17  are more effective for treatment of a shallow tumor, since the intersection area will occur before the X-rays hit the body, while the non inverted embodiments are more effective for deeper tumor treatments since the intersection area is a minor phenomenon or located outside of the patient&#39;s body. 
         [0108]    An additional benefit of the current invention is in the use of single crystals exhibiting some degree of mosaicity. The focal tracks thus created by the present invention are characterized by three-dimensional broadening which serves the purpose of allowing for homogeneity of the created radiation pattern within the target volume. 
         [0109]    The present invention is specifically advantageous in assembling multiple reflecting surfaces of elements having the same crystallographic plane index for different surfaces. In the case of double reflection arrangement, the dependency of the setup on Bragg angle is further avoided, and thus the limitations caused by higher order low reflectivity Miller index are overcome. Thus, the present invention provides multiple low order and high reflectivity surfaces. 
         [0110]    Special benefits can be made in cases where the body has to be irradiated from the front, e.g. after breast mastectomy. The existing technology provides irradiation of the entire depth of the body over relatively large area. The current invention provides a high convergence angle. Thus, utilizing the high convergence angle yields a large attenuation after the target volume, spearing healthy tissues.