Apparatus and method for scattered radiation correction

Abstract

A method for scattered radiation correction acquires radiographic projection image data for a first portion of a subject that lies within a field of view of an imaging apparatus and characterizes the surface contour of the subject that includes at least a second portion of the subject that lies outside the field of view of the imaging apparatus. The surface contour of the subject is characterized according to the reflectance images. The surface contour characterization is registered to the field of view. Scattered radiation is estimated according to the projection image data and the surface contour characterization. The acquired radiographic projection image data is updated according to the estimated scattered radiation. An image of the field of view is displayed according to the conditioned acquired radiographic projection image data.

What is claimed is: 
     
         1 . A method for scattered radiation correction, comprising:
 acquiring radiographic projection image data of a first portion of a subject that lies within a field of view of an imaging apparatus;   characterizing a surface contour of the subject, wherein the surface contour includes at least a second portion of the subject that lies outside the field of view of the imaging apparatus;   registering the surface contour characterization to the field of view of the acquired projection image data;   estimating scattered radiation according to both the acquired projection image data and the surface contour characterization;   conditioning the acquired radiographic projection image data according to the estimated scattered radiation; and   displaying, storing, or transmitting an image corresponding to the field of view according to the conditioned acquired radiographic projection image data.   
     
     
         2 . The method of  claim 1  wherein characterizing the surface contour of the subject comprises acquiring a plurality of reflectance images of the subject. 
     
     
         3 . The method of  claim 2  wherein acquiring the plurality of reflectance images of the subject further comprises recording a pattern of light that is directed onto the subject. 
     
     
         4 . The method of  claim 1  wherein acquiring the projection image data comprises acquiring a plurality of projection images of the subject, each projection image at a different angle with respect to the subject. 
     
     
         5 . The method of  claim 4  further comprising forming a reconstructed volume image from the acquired projection image data. 
     
     
         6 . A method for scattered radiation correction, comprising:
 acquiring radiographic projection image data of a first portion of a subject that lies within a field of view;   forming a reconstructed volume image from the acquired projection image data;   acquiring a plurality of reflectance images of the subject, including at least a second portion of the subject outside the field of view that contains the first portion;   characterizing a surface contour of the subject according to the plurality of reflectance images;   registering the surface contour characterization to the reconstructed volume image;   forming an extended volume image according to the reconstructed volume image and the surface contour characterization;   estimating scattered radiation according to the extended volume image;   updating the acquired radiographic projection image data according to the estimated scattered radiation;   conditioning the reconstructed volume image according to the updated projection images; and   displaying, storing, or transmitting the conditioned reconstructed volume image.   
     
     
         7 . The method of  claim 6  wherein acquiring the plurality of reflectance images comprises using one or more surface imaging apparatus mounted to a rotational gantry of an x-ray imaging system. 
     
     
         8 . The method of  claim 6  wherein acquiring the plurality of reflectance images comprises using one or more imaging apparatus coupled to a bore of an x-ray imaging system. 
     
     
         9 . The method of  claim 6  wherein acquiring the plurality of reflectance images comprises using one of a stereovision technique, a structured light technique, a structure from motion technique, and a time-of-flight technique. 
     
     
         10 . The method of  claim 6  wherein forming the extended volume image comprises assigning volume image data to the at least the second portion of the subject. 
     
     
         11 . The method of  claim 6  further comprising assigning to the at least the second portion one of a single uniform material/body tissue, a plurality of materials/body tissues, and one or more anatomical structures. 
     
     
         12 . The method of  claim 6  wherein assigning to the at least the second portion volume image data comprises using a plurality of materials/body tissues with anatomical structures from one of an acquired 3D surface model, a reconstructed 3D volume, an organ atlas, and one or more medical images stored in a database. 
     
     
         13 . The method of  claim 6 , wherein estimating the scattered radiation comprises using a Monte Carlo based method. 
     
     
         14 . A scattered radiation correction method for 2D X-ray imaging, comprising:
 acquiring projection data of a subject within a field of view of an imaging apparatus;   acquiring a surface contour of the subject, including at least the field of view and a portion of the peripheral part of the subject lying outside the field of view;   registering the surface contour to the imaged field of view based on the acquired projection data;   estimating scattered radiation within the projection data according to the acquired surface contour; and   correcting the acquired projection images according to the estimated scattered radiation.   
     
     
         15 . The method of  claim 14  further comprising generating extended volume images by filling one or more portions of the surface contour with one of a single uniform material/body tissue or a plurality of materials/body tissues with anatomical structures. 
     
     
         16 . The method of  claim 14  further comprising generating extended volume images using a plurality of materials/body tissues with anatomical structures from one of the acquired surface images, the acquired projection images, the previously reconstructed volume images, an organ atlas, and one or more medical images stored in a database. 
     
     
         17 . The method of  claim 14  further comprising generating one or more extended volume images by generating an extended volume within the field of view by cropping, deforming, resizing, stretching, rotating, or reorganizing anatomical structures of medical images stored in a database to match a forward projection of a synthetic volume within the field of view to the acquired projection data. 
     
     
         18 . The method of  claim 14  further comprising generating one or more extended volume images by generating an extended volume outside the field of view by cropping, deforming, resizing, stretching, rotating, or reorganizing anatomical structures of medical images stored in a database to match the acquired surface contour. 
     
     
         19 . The method of  claim 14 , wherein estimating the scattered radiation comprises using a statistical-based algorithm or a deterministic-based algorithm. 
     
     
         20 . The method of  claim 14 , wherein the corrected projection data is displayed on a monitor or stored to a disk. 
     
     
         21 . An apparatus for obtaining a volume image of a patient, comprising:
 a radiographic volume imaging apparatus that has an x-ray source and at least one x-ray detector;   a scanner configured to acquire surface contour for the patient;   a computer programmed with instructions to: (i) acquire images from the radiographic volume imaging apparatus and reconstruct a 3-D volume image of a volume of interest of the patient, (ii) acquire a surface contour of the patient, (iii) register the acquired surface contour with the reconstructed 3D volume image, (iv) form an extended volume image that includes peripheral portions outside the volume of interest and the volume of interest, and (v) condition the 3D volume image of the volume of interest according to the extended volume image; and   a display in signal communication with the computer.