Methods and apparatus for displaying images

Abstract

In one aspect, a method of displaying data is provided. The method comprises obtaining projection data of an object by exposing an object to radiation at a plurality of view angles and detecting at least some of the radiation exiting the object to form the projection data, operating a computer to reconstruct the projection data at a reconstruction resolution to form image data comprising a plurality of voxels representing locations within the object, each of the plurality of voxels being assigned an associated intensity indicative of a density of the subject matter at the respective location, determining a maximum resolution for display, above which variation in intensity between adjacent voxels is not supported by information in the projection data, the maximum resolution being less than the reconstruction resolution, and displaying the image data at or below the maximum resolution.

1 . A method of displaying image data, the method comprising: 
 obtaining projection data of an object by exposing an object to radiation at a plurality of view angles and detecting at least some of the radiation exiting the object to form the projection data;    operating a computer to reconstruct the projection data at a reconstruction resolution to form image data comprising a plurality of voxels representing locations within the object, each of the plurality of voxels being assigned an associated intensity indicative of a density of the subject matter at the respective location;    determining a maximum resolution for display, above which variation in intensity between adjacent voxels is not supported by information in the projection data, the maximum resolution being less than the reconstruction resolution; and    displaying the image data at or below the maximum resolution.    
     
     
         2 . The method of  claim 1 , wherein determining the maximum resolution includes determining the maximum resolution based on the number and distribution of the plurality of view angles from which the image data was obtained.  
     
     
         3 . The method of  claim 2 , operating a computer includes operating a computer to reconstruct the projection data to form a three-dimensional image having asymmetric resolution, a first resolution along a first dimension of the three-dimensions being  
     
     
         4 . The method of  claim 1 , wherein obtaining projection data includes obtaining projection data by exposing the object to x-ray radiation, from at least one x-ray source, at a plurality of view angles and detecting at least some of the radiation exiting the object to form the projection data, the projection data indicative of the amount of x-ray radiation absorbed by the object.  
     
     
         5 . The method of  claim 4 , wherein the object is a human female breast, and wherein obtaining projection data includes obtaining projection data by exposing the female human breast to x-ray radiation from a plurality of view angles number less than  30 .  
     
     
         6 . A method of transforming image data for display, the image data represented by a plurality of voxels, each having an associated intensity, the method comprising computer implemented acts of: 
 grouping the plurality of voxels into a plurality of neighborhoods; and    transforming each of the plurality of neighborhoods into a respective representative voxel having a representative intensity computed by: 
 substracting an offset from each voxel intensity in the respective neighborhood,  
 averaging the offset voxel intensities in the respective neighborhood to obtain an average intensity, and  
 adding the offset to the average intensity to form the representative intensity for the respective neighborhood.  
   
     
     
         7 . The method of  claim 6 , wherein averaging comprises: 
 performing a power function on each of the offset voxel intensity values to form a plurality of power offset voxel intensities;    averaging the plurality of power offset voxel intensities to form a power average intensity for the neighborhood; and    performing an inverse power function on the power average intensity to obtain the average intensity.    
     
     
         8 . The method of  claim 7 , wherein: 
 performing the power function includes squaring each of the offset voxel intensity values to form a plurality of squared offset voxel intensities; and    performing an inverse power function includes taking a square root of the power average intensity.    
     
     
         9 . A method of limiting a viewing angle at which image data may be displayed, the image data reconstructed from projection data obtained by exposing an object to radiation from a plurality of view angles spanning a range having a first angle boundary and a second angle boundary, the method comprising computer implemented acts of: 
 receiving an indicator from an operator to view the image data from a first angle;    displaying the image data on a display from the first angle if the first angle is within the range bounded by the first angle boundary and the second angle boundary; and    preventing the image data from being displayed on the display at the first angle if the first angle is outside of the range bounded by the first angle boundary and the second angle boundary.    
     
     
         10 . A method of displaying three-dimensional reconstruction image data formed from a plurality of slices, each of the plurality of slices having a voxel dimension N×M×1 in a first direction, a second direction and a third direction, respectively, the plurality of slices ordered in the third direction, the method comprising computer implemented acts of: 
 defining a window having a voxel width in the third direction equal to a predetermined number of slices of the image data;    aligning the window with a first plurality of slices to be displayed;    transforming the voxels of the first set of slices within the window into voxels of a first display slice;    providing the display slice to the display for viewing;    upon receiving an indication to display image data at a subsequent location in the third direction;    moving the window one slice of the ordered plurality of slices in the third direction to align the window with a second set of slices;    transforming the voxels of the second set of slices within the window into voxels of a second display slice; and    providing the display slice to the display for viewing.    
     
     
         11 . The method of  claim 10 , wherein the window has a voxel width that includes a number of slices at least equal to a resolution reduction factor between a reconstruction resolution of the image data and a display resolution of the image data in the third direction.  
     
     
         12 . The method of  claim 11 , wherein the window includes a central portion having a voxel width equal to the resolution reduction factor and a first peripheral portion located on a first side of the central portion having a voxel width of at least one slice, and a second peripheral portion located on a second side of the central portion having a voxel width of at least one slice, and wherein transforming voxels within the window includes weighting voxels of the at least one slice within the first peripheral portion and voxels within the at least one slice within the second peripheral portion less than the voxels of slices within the central portion.