Edge effects treatment for crystals

Abstract

A scintillator, for use in a radiation imaging device, has a light-emitting face, a radiation receiving face, and a perimeter extending between the light-emitting face and the radiation receiving face, the perimeter including an edge, the edge having an edge thickness. The scintillator emits scintillation light from the light emitting face in response to radiation incident on the radiation receiving face. The scintillator has one or more light guides formed therein with guides within a peripheral region being deeper than guides in a non-peripheral region.

1 . A radiation detector comprising: 
 a continuous body of scintillation material, the body-having a light-emitting face, a radiation receiving face, and a perimeter extending between the light-emitting face and the radiation receiving face, the perimeter including an edge, the edge having an edge thickness;    the body of scintillation material emitting scintillation light from the light emitting face in response to radiation incident on the radiation receiving face;    the body of scintillation material having a peripheral region proximate to the edge and a non-peripheral region spaced from the edge; and    the body of scintillation material including a plurality of spaced apart light guides formed in the peripheral region and in the non-peripheral region, each of the light guides being operable to redirect a portion of scintillation light before the portion of scintillation light emerges from the light emitting face;    wherein each of the light guides has a depth, the depth of each light guide in the peripheral region being greater than the depth of the light guides in the non-peripheral region.    
   
   
       2 . The radiation detector of  claim 1 , wherein the depth of the light guides is inversely correlated with the distance of the light guide from the edge.  
   
   
       3 . The radiation detector of  claim 2 , wherein the inverse correlation is a linear correlation.  
   
   
       4 . The radiation detector of  claim 1 , wherein at least two of the light guides in the non-peripheral region having the same depth.  
   
   
       5 . The radiation detector of  claim 4 , wherein each of the light guides in the non-peripheral region have the same depth.  
   
   
       6 . The radiation detector of  claim 1 , further comprising a plurality of light sensors, the sensors receiving scintillation light, the sensors each having a sensor diameter, 
 the peripheral region being a region within a distance approximately equal to a sensor diameter from the edge.    
   
   
       7 . The radiation detector of  claim 1 , wherein the non-peripheral region is larger than the peripheral region.  
   
   
       8 . The radiation detector of  claim 1 , wherein the peripheral region lies within a distance approximately equal to eight times the edge thickness from the edge.  
   
   
       9 . The radiation detector of  claim 1 , wherein the light guides comprise grooves formed in the light emitting face or the radiation receiving face.  
   
   
       10 . The radiation detector of  claim 1 , wherein the light guides comprise reflecting films.  
   
   
       11 . The radiation detector of  claim 1 , wherein the light guides each comprise an interface between two regions of different refractive indices.  
   
   
       12 . The radiation detector of  claim 1 , wherein each light guide provides an internal reflection of scintillation light within the body of scintillation material.  
   
   
       13 . The radiation detector of  claim 1 , wherein the light guides are each substantially parallel to the edge.  
   
   
       14 . The radiation detector of  claim 1 , wherein each of the light guides is disposed generally in a plane defined perpendicular to one of the faces of the body.  
   
   
       15 . The radiation detector of  claim 1 , wherein the perimeter includes a first pair of opposed edges and a second pair of opposed edges each extending between the first pair of edges, the peripheral region including regions adjacent each of the first pair of edges.  
   
   
       16 . The radiation detector of  claim 1 , wherein the plurality of spaced apart light guides are generally evenly spaced.  
   
   
       17 . The radiation detector of  claim 1 , wherein some of the plurality of light guides extend from the light-emitting face part way to the radiation receiving face.  
   
   
       18 . The radiation detector of  claim 1 , wherein some of the plurality of light guides extend from the radiation receiving face part way to the light-emitting face.  
   
   
       19 . The radiation detector of  claim 1 , further comprising a window disposed adjacent the light-emitting face of the body of scintillation material, the window being formed of a material substantially transparent to scintillation light, the window having at least one light guide formed therein.  
   
   
       20 . The radiation detector of  claim 1 , further comprising an optical transmission element disposed adjacent the radiation receiving face of the body of scintillation material, the optical transmission element having at least one light guide formed therein.  
   
   
       21 . The radiation detector of  claim 1 , wherein the perimeter includes a first pair of opposed edges and a second pair of opposed edges each extending between the first pair of edges, the peripheral region including regions adjacent each of the first pair of edges.  
   
   
       22 . The radiation detector of  claim 21 , wherein the body of scintillation material is generally rectangular and the edges are each generally straight edges.  
   
   
       23 . The radiation detector of  claim 21 , wherein the body of scintillation material is generally curved, the first pair of opposed edges being parallel generally straight edges and the second pair of opposed edges being curved edges.  
   
   
       24 . A radiation detector, comprising: 
 a scintillator producing scintillation light in response to incident radiation, the scintillator having a radiation receiving face, and a light emitting face, and a perimeter edge;    an array of sensors, each sensor in optical communication with the light emitting face of the scintillator, each light sensor having a light sensor diameter;    a window between the scintillator and the array of light sensors, the window having a first face, and a second face, and a perimeter edge;    a perimeter region being defined adjacent the perimeter edges of the scintillator and window and a central region being defined inboard of the perimeter region;    the scintillator or the window having a plurality of grooves formed in one face thereof, the grooves each having a depth and being formed in the perimeter region and in the central region, the depth of the grooves in the perimeter region being greater than the depth of the grooves in the central region    
   
   
       25 . A method of treating an optical material so as to modify the effect of internal edge reflections, the optical material having a face bounded by a perimeter, the perimeter including an edge, the method comprising: 
 forming a plurality of grooves spaced apart across the face, each of the grooves having a depth;    the face having a peripheral region proximate to the edge and a non-peripheral region spaced from the edge;    the depth of the grooves in the peripheral region being greater than the depth of the grooves in the non-peripheral region.    
   
   
       26 . The method of  claim 25 , wherein the grooves are formed by cutting the optical material.  
   
   
       27 . The method of  claim 25 , wherein the optical material is a scintillator.