Radiation Modulator

Abstract

A radiation beam modulator for modulating a radiation beam in a radiation system, includes an array of multiple columns of a radiation modulating fluid or liquid and a height adjuster which adjusts the heights of the multiple fluid columns so that the adjusted columns collectively will form a target radiation modulating profile. In a first embodiment, the modulator includes a bundle of capillaries in which the modulating fluid is conveyed to form the columns. An antagonizing fluid is conveyed into an opposite end of the capillaries to lock the modulating fluid in position between adjustments. In a second embodiment, the modulator includes a bath of the modulating fluid, in which bars can be immersed and retracted to generate the target radiation modulating profile.

1 - 25 . (canceled) 
   
   
       26 . A radiation beam modulator ( 1 ;  500 ;  600 ) comprising:
 a bath ( 590 ;  690 ) containing a radiation attenuating fluid ( 520 ;  620 );   multiple low radiation attenuating bars ( 570 ;  670 ) immersed in said radiation modulating fluid ( 520 ;  620 ) to form an array of multiple fluid columns ( 525 ;  625 ); and   a height adjuster ( 530 ;  630 ) for adjusting a respective level of immersion of said multiple bars ( 570 ;  670 ) in said radiation modulating fluid ( 520 ;  620 ) to thereby adjust the heights of said multiple fluid columns ( 525 ;  625 ) such that said multiple columns ( 525 ;  625 ) collectively form a radiation beam modulating profile.   
   
   
       27 . The modulator according to  claim 26 , wherein said height adjuster ( 530 ;  630 ) is adapted for individually adjusting said heights of said multiple fluid columns ( 525 ;  625 ). 
   
   
       28 . The modulator according to  claim 26 , further comprising means ( 530 ;  630 ) for actively maintaining said adjusted heights of said multiple fluid columns ( 525 ;  625 ). 
   
   
       29 . The modulator according to  claim 26 , wherein said radiation modulating fluid ( 520 ;  620 ) is in liquid form at operation temperature. 
   
   
       30 . The modulator according to  claim 26 , wherein said radiation modulating fluid ( 520 ;  620 ) is a radiation attenuating fluid selected from:
 mercury;   liquid Rose's metal; and   liquid Wood's metal.   
   
   
       31 . The modulator according to  claim 26 , wherein said multiple bars ( 570 ;  670 ) are made of at least one of:
 a low atomic number metal;   beryllium; and   a radiation-resistant plastic.   
   
   
       32 . The modulator according to  claim 26 , wherein each of said multiple bars ( 570 ;  670 ) has a hexagonal cross-section. 
   
   
       33 . The modulator according to  claim 26 , further comprising means ( 590 ;  690 ) for squeezing said multiple bars ( 570 ;  670 ) together to reduce fluid leakage between said multiple bars ( 570 ;  670 ). 
   
   
       34 . The modulator according to  claim 26 , further comprising multiple wire loops ( 580 ), where a first end ( 582 ) of a wire ( 580 ) of said multiple wire loops ( 580 ) is connected to a first end ( 572 ) of a bar ( 570 ) of said multiple bars ( 570 ) and a second end ( 584 ) of said wire ( 580 ) is connected to a second opposite end ( 574 ) of said bar ( 570 ), said height adjuster ( 530 ) comprises a motor system ( 535 ) connected to said multiple wire loops ( 580 ) and adapted for adjusting said respective level of immersion of said multiple bars ( 570 ) in said radiation modulating fluid ( 520 ) by rotating said multiple wire loops ( 580 ). 
   
   
       35 . The modulator according to  claim 26 , wherein each of said multiple bars ( 670 ) has a blind bore ( 676 ) in an end ( 674 ) and a nut ( 678 ) arranged in connection with said blind bore ( 676 ), said modulator ( 600 ) further comprises multiple screws ( 680 ) attached, through the screw heads ( 682 ), to a low radiation attenuation plate ( 687 ,  689 ) arranged in connection with said ends ( 674 ) of said multiple bars ( 670 ), said multiple screws ( 680 ) runs in said blind bores ( 676 ) through said nuts ( 678 ), and said height-adjuster ( 630 ) comprises means ( 635 ) for rotating said multiple screws ( 680 ) in order to adjust said respective level of immersion of said multiple bars ( 670 ) in said radiation modulating fluid ( 620 ). 
   
   
       36 . The modulator according to  claim 35 , wherein said height adjuster ( 630 ) comprises a system of screw drivers ( 635 ) adapted for individually rotating said multiple screws ( 680 ) in order to adjust said respective level of immersion of said multiple bars ( 670 ) in said radiation modulating fluid ( 620 ). 
   
   
       37 . The modulator according to  claim 35 , further comprising means ( 631 ,  633 ) for moving said rotating means ( 635 ) from at least one screwing position being substantially aligned with said plate ( 687 ,  689 ) to an irradiation position being away from said plate ( 687 ,  689 ). 
   
   
       38 . A radiation gantry ( 5 ) comprising:
 a radiation source for generating a radiation beam ( 10 ); and   a radiation beam modulator ( 1 ) according to  claim 26  for modulating said generated radiation beam ( 10 ).   
   
   
       39 . A method of operating a radiation beam modulator ( 1 ;  500 ;  600 ) according to  claim 26 , said method comprising adjusting said heights of said multiple fluid columns ( 525 ;  625 ) by adjusting a respective level of immersion of said multiple bars ( 570 ;  670 ) in said radiation modulating fluid ( 520 ;  620 ) contained in said bath ( 590 ;  690 ) such that said multiple columns ( 525 ;  625 ) collectively form a radiation beam modulating profile. 
   
   
       40 . The method according to  claim 39 , wherein said adjusting step comprises individually adjusting said heights of said multiple fluid columns ( 525 ;  625 ). 
   
   
       41 . The method according to  claim 39 , further comprising actively maintaining said adjusted heights of said multiple fluid columns ( 525 ;  625 ).