Machine for intraoperative radiation therapy

Abstract

A machine for intraoperative radiation therapy or IORT (Intra Operative Radio Therapy), includes a mobile body, having at least two driving wheels and at least an idle wheel, each driving wheel being operated by a corresponding moving engine, the machine including a radiating head connected to the body, for emitting an electron beam, handling elements which are integral with the radiating head, engine unit for moving the radiating head, for impressing to the radiating head at least a vertical translation motion. The handling elements include at least three bidirectional sensors, for measuring both a traction stress and a compression stress, each of which sends to a control processor an electric signal proportional to a measured stress which is orthogonal to the sensor. The control processor operates the moving engines of each driving wheel and the engine unit proportionally to the stresses measured by the at least three bidirectional sensors.

1 . Machine for intraoperative radiation therapy or IORT (Intra Operative Radio Therapy), comprising a mobile body, provided with at least two driving wheels ( 21 ,  22 ) and at least an idle wheel ( 24 ,  25 ), each driving wheel ( 21 ,  22 ) being operated by a corresponding moving engine, the machine comprising a radiating head ( 23 ) connected to the body, apt to emit an electron beam, the machine being characterised in that it further comprise handling means ( 19 ) which are integral with the radiating head ( 23 ), engine means for moving the radiating head ( 23 ), apt to impress to the radiating head ( 23 ) at least a vertical translation motion, said handling means ( 19 ) comprising at least three bidirectional sensors ( 20 ), apt to measure both a traction stress and a compression stress, each one of which sends to a control processor an electric signal which is proportional to a measured stress which is orthogonal to the sensor, said control processor operating the moving engines of each of said at least two driving wheels ( 21 ,  22 ) and the engine means for moving the radiating head ( 23 ) proportionally to the stresses which are measured by said at least three bidirectional sensors ( 20 ).  
   
   
       2 . Machine according to  claim 1 , characterised in that said engine means for moving the radiating head ( 23 ) is apt to impress to the radiating head ( 23 ) a rotational motion on at least a plane, in that said handling means ( 19 ) comprises at least four bidirectional sensors ( 20 ), and in that said control processor operates the moving engines of each of said at least two driving wheels ( 21 ,  22 ) and the engine means for moving the radiating head ( 23 ) on the basis of an orientation of said handling means ( 19 ).  
   
   
       3 . Machine according to  claim 2 , characterised in that said engine means for moving the radiating head ( 23 ) is apt to impress to the radiating head ( 23 ) a pitch rotational motion and a roll rotational motion, and in that said handling means ( 19 ) comprises at least five bidirectional sensors ( 20 ).  
   
   
       4 . Machine according to  claim 3 , characterised in that said control processor performs the following operations: 
 determining an orientation of the handling means ( 19 ) with respect to a first Cartesian triad which is integral with the body of the machine,    composing the stresses which are measured by the bidirectional sensors ( 20 ), obtaining a resulting vector and a resulting torque with respect to a second Cartesian triad which is integral with said handling means ( 19 ),    calculating the projections of the resulting vector and of the resulting torque onto the first fixed Cartesian triad, obtaining a vector of translation of the body, a torque of rotation of the body, a vector of vertical translation of the radiating head ( 23 ), a torque of roll rotation of the radiating head ( 23 ), and a torque of pitch rotation of the radiating head ( 23 ); and    operating the moving engines of each of said at least two driving wheels ( 21 ,  22 ), so as to linearly move the body proportionally to said vector of translation of the body and to rotate the body proportionally to said torque of rotation of the body, and operating the engines for moving the radiating head ( 23 ), so as to vertically translate the radiating head ( 23 ) proportionally to said vector of vertical translation of the radiating head ( 23 ), to impress a roll rotation to the radiating head ( 23 ) proportionally to said torque of roll rotation of the radiating head ( 23 ), and to impress a pitch rotation proportionally to said torque of pitch rotation of the radiating head ( 23 ).    
   
   
       5 . Machine according to  claim 1 , characterised in that each one of said at least three bidirectional sensors is formed by a pair of opposed sensors ( 20 ), each of which is apt to measure a compression stress which is orthogonal to it.  
   
   
       6 . Machine according to  claim 5 , characterised in that each one of said compression stress sensors ( 20 ) is inserted in a mechanical housing ( 26 ), provided with elastic means ( 27 ), mobile between a first not stressed limit position and a second limit position of maximum stress onto the sensor ( 20 ), wherein the maximum stress onto the sensor ( 20 ) is not larger than the full scale of this.  
   
   
       7 . Machine according to  claim 1 , characterised in that each one of said at least two driving wheels ( 21 ,  22 ) is provided with a clutch which is apt to uncouple the wheel from the respective engine making it idle.  
   
   
       8 . Machine according to  claim 1 , characterised in that it comprises housing compartments which are sealed against external humidity.  
   
   
       9 . Machine according to  claim 1 , characterised in that it has a weight lower than 400 Kg.  
   
   
       10 . Machine according to  claim 1 , characterised in that it has a width not larger than 100 cm, preferably not larger than 80 cm, and a length not longer than 2.5 metres, preferably not longer than 2 metres.  
   
   
       11 . Machine according to  claim 1 , characterised in that it is provided with a system for diffusing the electron beam, leaving an accelerating structure ( 4 ), which comprises a divergent magnetic lens ( 28 ), apt to make the trajectories of the electrons crossing it diverge.  
   
   
       12 . Machine according to  claim 1 , characterised in that it is provided with timer means apt to operate an acoustic device for a duration T before the start of the electron beam emission.  
   
   
       13 . Machine according to  claim 12 , characterised in that the duration T is adjustable.  
   
   
       14 . Machine according to  claim 1 , characterised in that it is provided with a system for measuring the total dose of the electron beam, emitted during a IORT treatment for a period of duration R, comprising an amperometric transformer, apt to measure the instantaneous current I beam  of the emitted electron beam, the instantaneous dose D being calculated as a function of said instantaneous current I beam , the total dose being calculated through a time integration of the instantaneous dose for the treatment period.  
   
   
       15 . Machine according to  claim 14 , characterised in that said instantaneous dose D is calculated on the basis of a quadratic dependency from said instantaneous current I beam : D=K*I beam   2 .  
   
   
       16 . Machine according to  claim 14 , characterised in that said instantaneous dose D is calculated on the basis of a linear dependency from said instantaneous current I beam ,  
     
       

       D=D 
       0 
       +A*ΔI 
       beam  

       where  
       ΔI beam =I beam −I beam     —     Ref  wherein I beam     —     Ref  is a reference value of the instantaneous current of the emitted electron beam, and  
       the coefficients Do and A are experimentally determined in a phase of clinical dosimetry of the machine.  
     
   
   
       17 . Machine according to  claim 1 , characterised in that the electron beam comes out from an accelerating structure ( 4 ) comprising tuning means ( 18 ,  47 ), placed in corresponding slots of the accelerating structure, said tuning means ( 18 ,  47 ) being directly and locally welded to the accelerating structure onto each of said slots through an electrical arc welding in controlled atmosphere.  
   
   
       18 . Machine according to  claim 17 , characterised in that the accelerating structure presents, in correspondence of each slot, a profile apt to dissipating heat.  
   
   
       19 . Machine according to  claim 17 , characterised in that said tuning means ( 18 ,  47 ) comprises a tuning screw ( 18 ) covered by a cap ( 45 ).  
   
   
       20 . Process for moving a machine for intraoperative radiation therapy or IORT (Intra Operative Radio Therapy), comprising a mobile body, provided with at least two driving wheels ( 21 ,  22 ) and at least an idle wheel ( 24 ,  25 ), each driving wheel ( 21 ,  22 ) being operated by a corresponding moving engine, the machine comprising a radiating head ( 23 ) connected to the body, apt to emit an electron beam, the machine further comprising handling means ( 19 ) which is integral with the radiating head ( 23 ), engine means for moving the radiating head ( 23 ) and which is apt to impress to the radiating head ( 23 ) a vertical translation motion, a pitch rotational motion and a roll rotational motion, said handling means ( 19 ) comprising at least five bidirectional sensors ( 20 ), the process being characterised in that it comprises the following step: 
 determining an orientation of the handling means ( 19 ) with respect to a first Cartesian triad which is integral with the body of the machine,    composing the stresses which are measured by the bidirectional sensors ( 20 ), obtaining a resulting vector and a resulting torque with respect to a second Cartesian triad which is integral with said handling means ( 19 ),    calculating the projections of the resulting vector and of the resulting torque onto the first fixed Cartesian triad, obtaining a vector of translation of the body, a torque of rotation of the body, a vector of vertical translation of the radiating head ( 23 ), a torque of roll rotation of the radiating head ( 23 ), and a torque of pitch rotation of the radiating head ( 23 ); and    operating the moving engines of each of said at least two driving wheels ( 21 ,  22 ), so as to linearly move the body proportionally to said vector of translation of the body and to rotate the body proportionally to said torque of rotation of the body, and operating the engines for moving the radiating head ( 23 ), so as to vertically translate the radiating head ( 23 ) proportionally to said vector of vertical translation of the radiating head ( 23 ), to impress a roll rotation to the radiating head ( 23 ) proportionally to said torque of roll rotation of the radiating head ( 23 ), and to impress a pitch rotation proportionally to said torque of pitch rotation of the radiating head ( 23 ).