Tomosynthesis imaging system and method

Abstract

A system for three-dimensional tomosynthesis imaging of a target element is provided having an image acquisition element and a processor. The image acquisition element obtains a plurality of images of the target element from a plurality of angles and includes a radiation source that is positionable at a plurality of angles with respect to the target element and a radiation detector. The radiation detector is positioned so as to detect radiation emitted by the radiation source passing through the target element and determine a plurality of attenuation values for radiation passing through the target element to establish a radiation absorbance projection image of the target element for a particular radiation source angle. The processor is configured to apply an iterative reconstruction algorithm to the radiation absorbance projection images of the target element obtained from a plurality of radiation source angles to generate a three-dimensional reconstruction of the target element. The system can gain further accuracy where the iterative reconstruction algorithm is applied using cone-beam forward projection and back projection.

1 . A tomosynthesis method for creating a three-dimensional reconstruction of a target element comprising:
 acquiring radiation absorbance images of the target element through a limited plurality of angles; and   applying an iterative reconstruction algorithm to generate the three-dimensional reconstruction of the target element;   wherein the iterative reconstruction algorithm is applied using cone-beam forward projection and back projection.   
     
     
         2 . A method according to  claim 1 , wherein the radiation absorbance images are acquired by transmitting x-ray energy from an x-ray source through the target element to an x-ray detector. 
     
     
         3 . A method according to  claim 2 , wherein the x-ray detector is a digital x-ray detector having a plurality of detector pixels. 
     
     
         4 . A method according to  claim 1 , wherein radiation absorbance images are acquired through a number of angles that is less than or equal to about 100. 
     
     
         5 . A method according to  claim 1 , wherein radiation absorbance images are acquired through a range of angles that is between about 30 and 120 degrees. 
     
     
         6 . A method according to  claim 1 , wherein the iterative reconstruction algorithm is a maximum likelihood algorithm. 
     
     
         7 . A method according to  claim 3 , wherein the three-dimensional reconstruction of the target element is represented as an array of voxels having a uniform or non-uniform size in three-dimensions. 
     
     
         8 . A method according to  claim 7 , wherein a forward projection step is implemented by ray tracing from the x-ray source to a detector pixel and the forward projection of the target element is obtained by repeating the ray tracing for each detector pixel to calculate an attenuation value for each voxel. 
     
     
         9 . A method according to  claim 8 , wherein a back projection step is implemented by locating detector pixels containing attenuation information relating to a selected voxel and using those pixels to update the attenuation value of the selected voxel. 
     
     
         10 . A method according to  claim 9 , wherein the back projection step includes performing a back projection for at least each voxel corresponding to a three-dimensional reconstruction of the target element. 
     
     
         11 . A method according to  claim 6 , wherein the maximum-likelihood estimation is implemented using an expectation-maximization algorithm. 
     
     
         12 . A method according to  claim 1 , wherein the target element is at least a portion of a human patient. 
     
     
         13 . A method according to  claim 12 , wherein the target element is a breast of a female human patient. 
     
     
         14 . A method according to  claim 1 , wherein the number of iterations is less than or equal to about 10. 
     
     
         15 . A system for three-dimensional tomosynthesis imaging of a target element comprising:
 an image acquisition element for obtaining a plurality of images of the target element from a plurality of angles having:
 a radiation source positionable at a plurality of angles with respect to the target element; and 
 a radiation detector positioned so as to detect radiation emitted by the radiation source passing through the target element and determine a plurality of attenuation value for radiation passing through the target element to establish a radiation absorbance projection image of the target element for a particular radiation source angle; and 
   a processor configured to apply an iterative reconstruction algorithm to the radiation absorbance projection images of the target element obtained from a plurality of radiation source angles to generate a three-dimensional reconstruction of the target element wherein the iterative reconstruction algorithm is applied using cone-beam forward projection and back projection.   
     
     
         16 . A system according to  claim 15 , wherein the radiation detector is a digital x-ray detector having a plurality of detector pixels. 
     
     
         17 . A system according to  claim 15 , wherein radiation absorbance projection images are acquired through a number of angles that is less than or equal to about 100. 
     
     
         18 . A system according to  claim 15 , wherein radiation absorbance projection images are acquired through a range of angles that is between about 30 and 120 degrees. 
     
     
         19 . A system according to  claim 15 , wherein the iterative reconstruction algorithm is a maximum likelihood algorithm. 
     
     
         20 . A system according to  claim 16 , wherein the three-dimensional reconstruction of the target element is represented as an array of voxels having a uniform or non-uniform size in three-dimensions. 
     
     
         21 . A system according to  claim 20 , wherein a forward projection step is implemented by ray tracing from the radiation source to a detector pixel and the forward projection of the target element is obtained by repeating the ray tracing for each detector pixel to calculate an attenuation value for each voxel. 
     
     
         22 . A system according to  claim 21 , wherein a back projection step is implemented by locating detector pixels containing attenuation information relating to a selected voxel and using those pixels to update the attenuation value of the selected voxel. 
     
     
         23 . A system according to  claim 22 , wherein the back projection step includes performing a back projection for at least each voxel corresponding to a three-dimensional reconstruction of the target element. 
     
     
         24 . A system according to  claim 19 , wherein the maximum-likelihood estimation is implemented using an expectation-maximization algorithm. 
     
     
         25 . A computer program for three-dimensional tomosynthesis imaging of a target element from a plurality of radiation absorbance projection images obtained at a different angles from an image acquisition element having a radiation source positionable at a plurality of angles with respect to the target element and a radiation detector positioned so as to detect radiation emitted by the radiation source passing through the target element and determine a plurality of attenuation value for radiation passing through the target element to establish a radiation absorbance projection image of the target element for a particular radiation source angle, the computer program code being embodied in a computer readable medium and comprising:
 computer program code for applying an iterative reconstruction algorithm to the radiation absorbance projection images of the target element obtained from a plurality of radiation source angles to generate the three-dimensional reconstruction of the target element wherein the iterative reconstruction algorithm is applied using cone-beam forward projection and back projection.   
     
     
         26 . A computer program according to  claim 25 , wherein the radiation detector is a digital x-ray detector having a plurality of detector pixels. 
     
     
         27 . A computer program according to  claim 25 , wherein radiation absorbance projection images are acquired through a number of angles that is less than or equal to about 100. 
     
     
         28 . A computer program according to  claim 25 , wherein radiation absorbance projection images are acquired through a range of angles that is between about 30 and 120 degrees. 
     
     
         29 . A computer program according to  claim 25 , wherein the iterative reconstruction algorithm is a maximum likelihood algorithm. 
     
     
         30 . A computer program according to  claim 26 , wherein the three-dimensional reconstruction of the target element is represented as an array of voxels having a uniform or non-uniform size in three-dimensions. 
     
     
         31 . A computer program according to  claim 30 , wherein a forward projection step is implemented by ray tracing from the radiation source to a detector pixel and the forward projection of the target element is obtained by repeating the ray tracing for each detector pixel to calculate an attenuation value for each voxel. 
     
     
         32 . A computer program according to  claim 31 , wherein a back projection step is implemented by locating detector pixels containing attenuation information relating to a selected voxel and using those pixels to update the attenuation value of the selected voxel. 
     
     
         33 . A computer program according to  claim 32 , wherein the back projection step includes performing a back projection for at least each voxel corresponding to a three-dimensional reconstruction of the target element. 
     
     
         34 . A computer program according to  claim 29 , wherein the maximum-likelihood estimation is implemented using an expectation-maximization algorithm.