Tomography scanner with axially discontinuous detector array

Abstract

A tomography scanner has intentionally designed, well defined gaps between detector rings with image reconstruction obtained with the use of conventional tomography data processing. The scanner is particularly advantageous as a small animal PET scanner.

1 . A tomography scanner comprising 
 a plurality of axially aligned detector rings forming a cylindrical detector array around a body to be imaged with well defined gaps between said detector rings, said detector rings producing signals in response to radiation emanating from the body in three dimensions; and    means responsive to said signals to produce tomographic image reconstruction throughout the axial field-of-view including said well defined gaps.    
   
   
       2 . A tomography scanner as recited in  claim 1  wherein said image reconstruction means includes means performing an iterative statistical or a classical image reconstruction process.  
   
   
       3 . A tomography scanner as recited in  claim 1  wherein said image reconstruction means uses 3D OSEM and 3D MAP algorithms.  
   
   
       4 . A tomography scanner as recited in  claim 1  wherein said image reconstruction means includes an iterative statistical reconstruction method that models some or all of the physics and geometry of the detector array.  
   
   
       5 . A tomography scanner as recited in  claim 1  wherein said image reconstruction means utilizes 3D Fourier re-binning followed by 2D filtered back projection.  
   
   
       6 . A tomography scanner as recited in  claim 1  wherein said image reconstruction means utilizes a 3D Fourier re-binning followed by a 2D iterative statistical reconstruction method.  
   
   
       7 . A tomography scanner as recited in  claim 1  wherein said image reconstruction means utilizes a 3D reprojection algorithm.  
   
   
       8 . A tomography scanner as recited in  claim 1  wherein said detector rings include a plurality of detector modules angled in an axial direction.  
   
   
       9 . A tomography scanner as recited in  claim 1  and further comprising means to provide relative reciprocating or unidirectional axial movement between the body to be imaged and said detector rings to reduce the effects of said gaps.  
   
   
       10 . A tomography scanner as recited in  claim 1  wherein said detector rings include a plurality of detector modules carrying a plurality of detector elements, each detector element having an axial dimension and said well defined gaps have an axial dimension greater than or equal to said axial dimensions of said detector elements.  
   
   
       11 . A tomography scanner as recited in  claim 10  wherein said well defined gaps each have an axial dimension at least three times greater than said axial dimension of said detector elements.  
   
   
       12 . A tomography scanner as recited in claim 1  wherein said detector rings each carry a plurality of detector elements having points of axial resolution with the spacing between said points defining pitch and said gaps have an axial dimension greater than said pitch.  
   
   
       13 . A positron emission tomography scanner comprising 
 a pair of detector rings forming a cylindrical detector array around a body to be imaged with a well defined gap between said detector rings;    a plurality of detector modules carried by said detector rings producing signals corresponding to the three dimensional points of interaction in each of a pair of said detector modules in response to detection of time coincident photons from positron annihilations in a body containing a positron emitting compound; and    means responsive to said signals to produce tomographic image reconstruction of the spatial distribution of the amount of positron emitting compound in the body along the axial field-of-view of said cylindrical detector array.    
   
   
       14 . A positron emission tomography scanner as recited in  claim 13  wherein said signal responsive means includes an iterative process.  
   
   
       15 . A positron emission tomography scanner as recited in  claim 13  wherein said signal responsive means provides classical reconstruction.  
   
   
       16 . A positron emission tomography scanner as recited in  claim 13  wherein said detector modules are angled in an axial direction to reduce the target area resulting from said gap.  
   
   
       17 . A positron emission tomography scanner as recited in  claim 13  and further comprising means to provide relative reciprocating axial movement between the animal and said detector array.  
   
   
       18 . A tomography scanner as recited in  claim 13  wherein said detector modules each contain at least one detector element having an axial dimension and said well defined gap has an axial dimension greater than said axial dimensions of said detector elements.  
   
   
       19 . A tomography scanner as recited in  claim 18  wherein said well defined gap has an axial dimension at least three times greater than said axial dimensions of said detector elements.