Kilovoltage delivery system for radiation therapy

Abstract

A small tabletop stationary five-degree of freedom device such as a “robot” is used to define the treatment region by tracing the region under direct visualization and then to precisely deliver the treatment plan created by an automatic planning system by positioning a single low energy radiation source, or a plurality of low energy sources connected to each other in a predetermined parallel or similar geometry, each source equipped with blocking and attenuation mechanisms, at a plurality of positions in a planar fashion across or through a selected treatment field, thereby delivering a plurality of parallel overlapping beams indexed on a millimeter or submillimeter grid such that a concentration of dose is achieved at a variable depth in tissue relative to the dose where the radiation first enters the tissue and can be used to treat regions on or below the surface of tissue, in a cavity and underlying region created following a surgical resection, on or below the surface of an internal cavity, hollow viscus, or lumen, or deep in tissue adjacent to an inserted probe or conduit or catheter. By generating a plurality of overlapping beams indexed on a millimeter or submillimeter grid that converge on a target volume loaded with gold nanoparticles, a tumorcidal dose of radiation can be delivered in as little as a single session to tumor cells but not to normal cells within or outside the treatment volume. This approach also makes it possible to deliver serial radiosurgical treatments.

1 . An apparatus for performing radiation therapy on a selected region of tissue in in proximity to said apparatus, said apparatus comprising: 
 (a) a means for generating beams of low energy radiation; and    (b) a means for disposing said beams in a precise and controllable manner from a plurality of positions indexed relative to each other in predetermined but variable millimeter or submillimeter increments so as to produce an at least one-dimensional array of beams that overlap in increasing amounts as they pass through tissue,    whereby the amount of radiation delivered at depth in tissue can be equal to or greater than the dose delivered to the tissue or other material through which the beams pass.    
   
   
       2 . The apparatus of  claim 1  wherein said means for generating comprises a radioactive source or an x-ray generating device emitting radiation of a variable or fixed energy in the kilovoltage or orthovoltage range.  
   
   
       3 . The apparatus of  claim 1  wherein said means for disposing comprises a robot or a multiple degree of freedom manipulator.  
   
   
       4 . The apparatus of  claim 1  wherein said means for disposing comprises an at least one-dimensional grid of channels or tubes placed on the surface of the patient or of an internal cavity or lumen or hollow viscus through which the radiation source can be indexed in a known and reproducible orientation.  
   
   
       5 . The apparatus of  claim 1  wherein said means for generating and said means for disposing comprises a scanning electron beam device that scans a small electron beam over an anode target in a predetermined pattern in order to generate a plurality of overlapping radiation beams.  
   
   
       6 . The apparatus of  claim 5  furthermore comprising a collimation system with an at least one-dimensional array of equally spaced apertures of known and defined but variable size acting as radiation transmissive passages through the collimator that serves to define the radiation beams.  
   
   
       7 . The apparatus of  claim 1  wherein said means for generating comprises an at least one dimensional array of said means of generating.  
   
   
       8 . The apparatus of  claim 1  furthermore comprising a means for attenuating or filtering each beam of radiation by a variable and predetermined and known amount so as to harden each beam or reduce the dose at the beam/tissue interface relative to the dose of radiation at depth.  
   
   
       9 . The apparatus of  claim 1  furthermore comprising a means for shaping the beam of radiation emitted by the radiation source in a variable and predetermined and known way so as to control the spread of the beam as it passes through tissue thereby influencing the amount the beam overlaps with other beams as it passes through tissue.  
   
   
       10 . The apparatus of  claim 1  furthermore comprising a means for defining and capturing electronically or digitally said region by tracing its outline or surface on or in or projected to the surface of the tissue.  
   
   
       11 . The apparatus of  claim 10  wherein said means for defining comprises a position localization system such as a 3-D digitizing arm, a passive or active camera localization system, an infrared localization system, a magnetic localization system, a sound-based localization system, a laser scanning system, a laser range finder system, a multiple degree of freedom manipulator, a robot with passive position acquisition capabilities.  
   
   
       12 . The apparatus of  claim 1  furthermore comprising a means for creating a treatment plan based on data entered defining the dose to be delivered to said region and specifying the depth and thickness of said region and the location of said region, whereby at least the coordinates of the plurality of said positions in the coordinate system of the means for disposing and the dose of radiation to be delivered for each position are defined and sent to said means for disposing and generating.  
   
   
       13 . The apparatus of  claim 12  furthermore having the means for specifying at least one of the following: 
 (a) the amount of attenuation or filtering for each position    (b) the amount of blocking for each position    (c) the energy for each beam position.    
   
   
       14 . The apparatus of  claim 1  furthermore comprising a means for determining if the patient has moved during the course of treatment and for terminating the treatment or modifying the coordinates of said positions in order to compensate for the amount and vector of movement.  
   
   
       15 . The apparatus of  claim 14  wherein the means for determining comprises a localization and tracking system that records and tracks the position of markers placed on the tissue surface in the vicinity of the region,  
     whereby the difference in the position of said markers between the time of region identification and the start and process of delivering the treatment can be determined, and  
     whereby the treatment can be terminated or adjustment made automatically to compensate for the detected movement in order to insure that the treatment is not delivered to an incorrect location.  
   
   
       16 . The apparatus of  claim 14  wherein the means for determining comprises: 
 (a) said means for generating used to image markers placed on the underside of the patient    (b) a means for detecting the radiation produced by the means for generating as the radiation exits the patient and passes through the markers    whereby the difference in the position of said markers between the time of region identification and the start and process of delivering the treatment can be determined, and    whereby the treatment can be terminated or adjustment made automatically to compensate for the detected movement in order to insure that the treatment is not delivered to an incorrect location.    
   
   
       17 . An apparatus for performing radiation therapy on a selected region of tissue in a patient, said apparatus comprising: 
 (a) a means for defining and capturing electronically or digitally said region by tracing its outline or surface on or in the patient and sending the data to a treatment planning system,    (b) a means for generating a treatment plan that defines, in order to treat said region, at least the plurality of positions in the coordinate system of a means for disposing radiation and the dose to be delivered at each position, as well as the attenuation, blocking and energy required for each position should means be provided for adjusting these parameters,    (c) a means for generating beams of low energy radiation,    (d) a means for disposing said beams in a precise and controllable manner from a plurality of positions indexed relative to each other in a predetermined but variable millimeter or submillimeter increments so as to produce an at least one-dimensional array of overlapping beams,    (e) a means for determining if the patient has moved during the course of treatment and for terminating the treatment or modifying the coordinates of said positions in order to compensate for the amount and vector of movement    whereby the amount of radiation delivered at depth in proximity to said means for generating can be made to be equal to or greater than the dose delivered to the tissue or other material through which the beams pass, said region being identified, planned for, and treated in a fully automated manner to the correct location.    
   
   
       18 . A method for delivering a dose of radiation to a region of tissue in a patient, comprising the steps of: 
 (a) generating beams of low energy radiation using a single radiation source or a plurality of radiation sources precisely aligned relative to each other with at least one beam of radiation generated by each source,    (b) disposing said generating means in a precise and controllable manner from a plurality of positions indexed relative to each other such that the plurality of beams are indexed relative to each other in predetermined but variable millimeter or submillimeter increments so as to produce an at least one-dimensional array of overlapping beams,    (c) attenuating or filtering to a variable but predetermined amount the beam from each radiation source if means are provided for so doing    (d) collimating or shaping in a variable but predetermined way the beam from each radiation source in order to control the amount of spread of the beam with increasing depth if means are provided for so doing,    (e) varying in a predetermined way the energy of each radiation source if means are provided for so doing,    whereby the dose of radiation delivered at depth to the region in proximity to said generating means can be made to be equal to or greater than the dose delivered to the tissue or other material through which the beams pass.    
   
   
       19 . The method of  claim 18  furthermore comprising the steps of: 
 (a) identifying said region directly on said patient with a localization system,    (b) transferring data from said localization system into a treatment planning system,    (c) entering into said planning system the dose of radiation to be delivered to said region and the thickness of said region and the position of said region relative to the tissue surface,    (d) generating a treatment plan for said region specifying at least the plurality of said positions and the dose to be delivered at each of said positions,    (e) generating also the amount of attenuation or filtering for each of said positions and the amount of blocking for each of said positions and the energy for each of said positions if the delivery device supports such features,    whereby the entire process of treatment, from region identification to treatment planning to treatment delivery can occur in a single setting in a fully integrated manner.    
   
   
       20 . The method of  claim 18  furthermore comprising the steps of: 
 (a) placing markers on the tissue surface in the vicinity of said region or markers on the underside of the patient    (b) identifying said region directly on the patient with a localization system    (c) defining and recording the position of the markers on said surface with said localization system at the time of identifying or of said markers on the underside using said means for generating    (d) defining and recording the position of the markers intermittently or continuously prior to and during treatment    (e) comparing the position of said markers acquired prior to the start and during treatment to their position at the time of region identification,    (f) indicating the amount of movement of said markers on an intermittent or continuous basis,    (g) terminating the treatment if required or adjusting the treatment delivery to account for the movement.    whereby the patient can be protected from having a treatment delivered to an incorrect location.    
   
   
       21 . The method of  claim 20  wherein said entering comprises adjusting the size and position of a graphical tool whereby the position of the dose to be delivered relative to the tissue surface and the thickness of the region to receive dose can be indicated in the planning system.  
   
   
       22 . An apparatus for delivering a dose of radiation to a region of tissue in a patient, said apparatus comprising: 
 (a) a means for generating beams of low energy radiation; and    (b) a means for disposing said beams in a precise and controllable manner from a plurality of positions indexed relative to each other in predetermined but variable millimeter or submillimeter increments so as to produce a two-dimensional array of beams that overlap and converge at a predetermined but variable depth in tissue,    whereby the amount of radiation delivered to the region is increased relative to the dose delivered to the tissue or other material through which the beams pass.    
   
   
       23 . The apparatus of  claim 22  wherein said means for generating comprises an x-ray generating device emitting radiation of a variable or fixed energy in the kilovoltage or orthovoltage range.  
   
   
       24 . The apparatus of  claim 22  wherein said means for disposing comprises a robot or a multiple degree of freedom manipulator.  
   
   
       25 . The apparatus of  claim 22  furthermore comprising a means for collimating each beam of radiation emitted by the radiation source in a variable and predetermined and known way so as to control the spread of each beam as it passes through tissue thereby influencing the amount the beam overlaps with other beams as it passes through tissue.  
   
   
       26 . The apparatus of  claim 22  wherein said means for generating said means for disposing comprises a scanning electron beam device that scans a small electron beam over an anode target in a predetermined pattern in order to generate a plurality of overlapping radiation beams.  
   
   
       27 . The apparatus of  claim 26  whereby said means is arranged along a radius equal to the focal point of said plurality.  
   
   
       28 . The apparatus of  claim 22  furthermore comprising a means for changing the position of a means of disposing relative to said region such that said array converges on said region.  
   
   
       29 . The apparatus of  claim 22  furthermore comprising a means for delivering a plurality of said array from a plurality of directions spaced about the patient such that the dose at the target volume is increased relative to the dose delivered to nontarget tissue when compared to the dose from the use of only one direction.  
   
   
       30 . The apparatus of  claim 22  furthermore comprising a means for changing the depth of highest concentration of dose by varying the energy of said array delivered from a given direction.  
   
   
       31 . The apparatus of  claim 22  furthermore comprising a means for enhancing said amount by loading the region of tissue with a high Z material.  
   
   
       32 . The apparatus of  claim 31  whereby the high Z material is delivered to the target through the use of a labeling material that identifies selectively or preferentially the desired target cells.  
   
   
       33 . The apparatus of  claim 22  furthermore comprising a means for imaging said beams after they pass through the patient comprising an x-ray detector interposed in the beam path outside the patient whereby at least one of the target location, amount of Z material in the target region, and effects of treatment can be determined.  
   
   
       34 . An apparatus for performing radiation therapy on a selected region of tissue in a patient, said apparatus comprising: 
 (a) a means for defining the region to be treated and for sending the data to a treatment planning system,    (b) a means for generating a treatment plan that defines in order to treat said region at least the plurality of positions in the coordinate system of a means for disposing radiation and the dose to be delivered at each position, and the collimation and the energy required for each position,    (c) a means for generating beams of low energy radiation,    (d) a means for disposing said beams in a precise and controllable manner from a plurality of positions indexed relative to each other in a predetermined but variable millimeter or submillimeter increments so as to produce a two-dimensional array of overlapping beams that converge at a predetermined but variable depth in tissue,    whereby the amount of radiation delivered at depth is increased relative to that delivered to the tissue or other material through which the beams pass.    
   
   
       35 . A method for delivering a dose of radiation to a region of tissue in a patient by generating from a given direction a plurality of beams of low energy radiation indexed relative to each other in predetermined but variable increments,  
     whereby a two-dimensional array of overlapping beams that converge at a specified but variable depth are created,  
     whereby the dose of radiation delivered at depth to the region is increased relative to the dose delivered to other tissue.  
   
   
       36 . The method of  claim 35  furthermore comprising the step of changing the position of a means for generating such that the overlapping beams converge on the target volume.  
   
   
       37 . The method of  claim 35  furthermore comprising the step of delivering said array from a plurality of directions spaced about the patient such that the dose at the target volume is increased relative to the dose delivered to nontarget tissue when compared to the dose from the use of only one direction.  
   
   
       38 . The method of  claim 35  furthermore comprising the step of changing the depth of highest concentration of dose by varying the energy of said array delivered from a given direction.  
   
   
       39 . The method of  claim 35  furthermore comprising the step of collimating in a variable but predetermined way said beams in order to control the amount of spread of the beams with increasing depth.  
   
   
       40 . The method of  claim 35  furthermore comprising the step of loading the target volume with a high Z material whereby the interaction of said array with the high Z material leads to an increase in dose in said target.  
   
   
       41 . The method of  claim 35  whereby said loading is accomplished by delivering the high Z material selectively or preferentially to the target cells through the use of a target-specific labeling material.  
   
   
       42 . The method of  claim 35  furthermore comprising the step of imaging said region using said array in conjunction with a detector placed in the path of said array as they exit the patient.  
   
   
       43 . A method for delivering a dose of radiation to a region of tissue in a patient, comprising the steps of: 
 (a) generating a plurality of beams of low energy radiation from a given direction such that the plurality of beams are indexed relative to each other in predetermined but variable increments so as to produce two-dimensional array of overlapping beams that converge at a specified but variable depth,    (b) delivering said array from a plurality of directions    (c) adjusting the depth of maximum dose from said array by varying the energy of said array or the focal point of said array,    (d) collimating in a variable but predetermined way said beams in order to control the amount of spread of the beam with increasing depth    whereby the dose of radiation delivered at depth to the region from the overlapping plurality of beams is increased relative to the dose delivered to other tissue.    
   
   
       44 . The method of  claim 43  furthermore comprising the steps of: 
 (a) imaging said region using said array in order to identify the location of said region    (b) transferring data from said imaging into a treatment planning system,    (c) entering into said planning system the dose of radiation to be delivered to said region and the thickness of said region and the position of said region relative to the tissue surface,    (d) generating a treatment plan for said region specifying at least the plurality of said positions, the collimation for said array, the energy for said array, and the dose to be delivered at each of said positions,    whereby the entire process of treatment, from region identification to treatment planning to treatment delivery can occur in a single setting in a fully integrated manner.    
   
   
       45 . The method of  claim 43  furthermore comprising the step of loading the target volume with a high Z material whereby the interaction of said array with the high Z material leads to an increase in dose in said target.  
   
   
       46 . The method of  claim 45  furthermore comprising the step of determining the amount of target loading with Z material by imaging the passage of said array through said region and the patient by a detector before and after loading whereby the amount of loading is related to the change in imaging characteristics of said region.