X-ray computerized tomographic apparatus

Abstract

An X-ray computerized tomographic apparatus includes an X-ray tube device configured to irradiate an object to be examined with a pyramidal X-ray beam, a detector which has a plurality of detecting elements arrayed in a slice direction in which X-rays transmitted through the object are detected, a data extending unit which creates virtual data corresponding to an extension region located outside a region in which the detecting elements are arranged in the slice direction on the basis of real data detected by the detecting element, and a reconstructing unit which reconstructs image data on the basis of the real data and virtual data.

1. An X-ray computerized tomographic apparatus, comprising:
 an X-ray tube device configured to irradiate an object to be examined with a pyramidal X-ray beam; 
 a detector which has a plurality of detecting elements arrayed in a slice direction in which X-rays transmitted through the object are detected; 
 a data extending unit configured to create virtual data corresponding to an extension region located outside a region in which the detecting elements are arranged in the slice direction on the basis of real data detected by the detecting element; and 
 a reconstructing unit configured to reconstruct image data on the basis of the real data and virtual data; 
 an input device which inputs a radius of the field of view; and 
 an extension region determining unit configured to determine a length of the extension region on the basis of the input radius of the field of view. 
 
     
     
       2. An apparatus according to  claim 1 , wherein said data extending unit uses real data detected by one of the plurality of detecting elements which is located at an outermost position as the virtual data. 
     
     
       3. An apparatus according to  claim 1 , wherein said data extending unit creates the virtual data on the basis of real data detected by one of the plurality of detecting elements which is located at an outermost position and real data detected by at least one detecting element adjacent to the detecting element located at the outermost position. 
     
     
       4. An apparatus according to  claim 3 , wherein said data extending unit creates the virtual data from the real data detected by the detecting element located at the outermost position and the real data detected by the adjacent detecting element by extrapolation. 
     
     
       5. An apparatus according to  claim 1 , wherein said data extending unit creates the virtual data on the basis of real data detected by one of the plurality of detecting elements which is located at an outermost position and real data detected by the detecting element immediately adjacent to the detecting element located at the outermost position. 
     
     
       6. An apparatus according to  claim 5 , wherein said data extending unit creates the virtual data from the real data detected by the detecting element located at the outermost position and the real data detected by the immediately adjacent detecting element by extrapolation. 
     
     
       7. An apparatus according to  claim 1 , further comprising:
 an input device which inputs a radius of the field of view; and   an extension region determining unit configured to determine a length of the extension region on the basis of the input radius of the field of view.   
     
     
       8. An apparatus according to claim  7  1, wherein said extension region length determining unit determines a length of the extension region to set an effective height of the field of view, within which the input radius of the field of view is maintained, to a predetermined length. 
     
     
       9. An apparatus according to  claim 8 , further comprising a storage device which stores a table in which different lengths of the extension region correspond with different radii associated with the field of view. 
     
     
       10. An apparatus according to claim  7  1, further comprising a GUI controller configured to provide a graphic user interface including choices associated with a plurality of regions to be examined so as to support inputting of a diameter of the field of view. 
     
     
       11. An apparatus according to claim  7  1, further comprising a GUI controller configured to provide a graphic user interface including choices associated with different sizes so as to support inputting of a diameter of the field of view. 
     
     
       12. An X-ray computerized tomographic apparatus, comprising:
 an X-ray tube device configured to irradiate an object to be examined with a pyramidal X-ray beam; 
 a detector which has a plurality of detecting elements arrayed in a slice direction in which X-rays transmitted through the object are detected; 
 an input device which inputs a radius of a field of view; and 
 a reconstructing unit configured to reconstruct image data about a field of view in which the input radius is maintained within a predetermined length range in the slice direction on the basis of real data detected by the detecting element and virtual data created from the real data, the virtual data corresponding to an extension region located outside a region in which the detecting elements are arranged in the slice direction and being created on the basis of real data detected by the detecting element. 
 
     
     
       13. An apparatus according to  claim 12 , further comprising a GUI controller configured to provide a graphic user interface including choices associated with a plurality of regions to be examined so as to support inputting of a diameter of the field of view. 
     
     
       14. An apparatus according to  claim 12 , further comprising a GUI controller configured to provide a graphic user interface including choices associated with different sizes so as to support inputting of a diameter of the field of view. 
     
     
       15. An X-ray computerized tomographic apparatus comprising:
 an X-ray tube device configured to irradiate an object to be examined with a pyramidal X-ray beam; 
 a detector which has a plurality of detecting elements arrayed in a slice direction in which X-rays transmitted through the object are detected; and 
 a reconstructing unit configured to reconstruct image data about a field of view having an arbitrary radius and fixed axis length on the basis of real data detected by the detecting element and virtual data created from the real data, the virtual data corresponding to an extension region located outside a region in which the detecting elements are arranged in the slice direction and being created on the basis of real data detected by the detecting element. 
 
     
     
       16. An apparatus according to  claim 15 , wherein the virtual data corresponds to an the extension region outside the region in which the detecting elements are arrayed. 
     
     
       17. An X-ray computerized tomographic apparatus comprising:
 an X-ray tube device configured to irradiate an object to be examined with a pyramidal X-ray beam; 
 a detector which has a plurality of detecting elements arrayed in a slice direction in which X-rays transmitted through the object are detected; 
 an input device which inputs a size of a field of view; and 
 a reconstructing unit configured to reconstruct image data about a field of view in which the input size is maintained within a predetermined length range in the slice direction on the basis of real data detected by the detecting element and virtual data created from the real data, the virtual data corresponding to an extension region located outside a region in which the detecting elements are arranged in the slice direction and being created on the basis of real data detected by the detecting element. 
 
     
     
       18. An X-ray computerized tomographic apparatus, comprising:
 an X-ray tube device configured to irradiate an object with an X-ray beam;   a detector having a plurality of detecting elements arrayed in a slice direction, the detecting elements configured to detect X-rays transmitted through the object;   a controller configured to perform a helical scan using said X-ray tube device and said detector to acquire projection data;   an input device configured to set a field of view and a helical pitch;   a determining unit configured to determine at least one weighting factor based on the field of view and the helical pitch; and   a reconstructing unit configured to reconstruct a tomographic image based on the projection data to which the at least one weighting factor is applied, using a cone-beam reconstruction method.   
     
     
       19. The apparatus of claim 18, wherein the reconstructing unit is configured to reconstruct the tomographic image using backprojection along a theoretical ray. 
     
     
       20. The apparatus of claim 18, wherein the X-ray tube device is configured to irradiate the object with a cone-shaped X-ray beam. 
     
     
       21. An apparatus according to claim 18, further comprising:
 a controller configured to perform a multi-helical scan using said X-ray tube device and said detector.   
     
     
       22. An apparatus according to claim 18, wherein said determining unit is configured to determine the at least one weighting factor based on a size of the set field of view; and
 said reconstructing unit is configured to apply the determined at least one weighting factor to the projection data to be reconstructed.   
     
     
       23. An apparatus according to claim 21, wherein said determining unit is configured to determine the at least one weighting factor based on a size of the set field of view; and
 said reconstructing unit is configured to apply the determined at least one weighting factor to the projection data to be reconstructed.   
     
     
       24. An apparatus according to claim 22, wherein said determining unit is configured to determine the at least one weighting factor for filling a missing region of the field of view. 
     
     
       25. An X-ray computerized tomographic apparatus, comprising:
 an X-ray tube device configured to irradiate an object with an X-ray beam;   a detector having a plurality of detecting elements arrayed in a slice direction, the detecting elements configured to detect X-rays transmitted through the object;   a controller configured to perform a multi-helical scan using said an X-ray tube device and said detector to acquire projection data;   a calculator configured to apply at least one weighting factor to the projection data to compensate for insufficient or unavailable projection data corresponding to a region of said object; and   a reconstructing unit configured to reconstruct a tomographic image in the region based on the weighted projection data using a cone beam reconstruction method.   
     
     
       26. An X-ray computerized tomographic apparatus, comprising:
 an X-ray tube device configured to irradiate an object with an X-ray beam;   a detector having a plurality of detecting elements arrayed in a slice direction, the detecting elements configured to detect X-rays transmitted through the object;   a controller configured to perform a multi-helical scan using said an X-ray tube device and said detector to acquire projection data;   a calculator configured to calculate, based on the acquired projection data, reconstruction projection data corresponding to an extension region located outside a region in the slice direction in which the detecting elements are arranged; and   a reconstructing unit configured to reconstruct a tomographic image based on the reconstruction projection data using a cone-beam reconstruction method.   
     
     
       27. A method of generating a tomographic image of an object, comprising:
 setting a field of view and a helical pitch;   obtaining projection data by a multi-helical scan;   determining at least one weighting factor based on the set field of view and helical pitch; and   reconstructing the tomographic image based on the projection data to which the weighting factor is applied using a cone-beam reconstruction method.   
     
     
       28. A method of producing a tomographic image of an object, comprising:
 obtaining projection data by irradiating the object with an X-ray beam in a multi-helical scan and detecting X-rays transmitted through the object using a detector having a plurality of detecting elements arrayed in a slice direction;   applying at least one weighting factor to the obtained projection data to compensate for insufficient or unavailable projection data corresponding to a region of said object; and   reconstructing the tomographic image in the region based on the weighted projection data using a cone-beam reconstruction method.   
     
     
       29. A method of producing a tomographic image of an object, comprising:
 obtaining projection data by irradiating the object with an X-ray beam in a helical scan and detecting X-rays transmitted through the object using a detector having a plurality of detecting elements arrayed in a slice direction;   calculating, based on the obtained projection data, reconstruction projection data corresponding to an extension region located outside a region in the slice direction in which the detecting elements are arranged; and   reconstructing the tomographic image based on the reconstruction projection data using a cone-beam reconstruction method.   
     
     
       30. An X-ray computerized tomographic apparatus, comprising:
 an X-ray tube device configured to irradiate an object with an X-ray beam;   a detector having a plurality of detecting elements arrayed in a slice direction, the detecting elements configured to detect X-rays transmitted through the object;   a controller configured to perform a multi-helical scan using said an X-ray tube device and said detector to acquire projection data;   a data extending unit configured to calculate, based on the projection data, reconstruction projection data corresponding to an extension region located outside a region in which the detecting elements are arranged; and   a reconstructing unit configured to reconstruct a tomographic image based on the reconstruction projection data using a cone-beam reconstruction method.   
     
     
       31. An X-ray computerized tomographic apparatus, comprising:
 an X-ray tube device configured to irradiate an object with an X-ray beam;   a detector having a plurality of detecting elements arrayed in a slice direction, the detecting elements configured to detect X-rays transmitted through the object;   a controller configured to perform a multi-helical scan using said an X-ray tube device and said detector to acquire projection data;   a data extending unit configured to apply at least one weighting factor to the acquired projection data to compensate for insufficient or unavailable projection data corresponding to a region of said object; and   a reconstructing unit configured to reconstruct a tomographic image in the region based on the weighted projection data using a cone beam reconstruction method.   
     
     
       32. An X-ray computerized tomographic apparatus, comprising:
 an X-ray tube device configured to irradiate an object with an X-ray beam;   a detector having a plurality of detecting elements arrayed in a slice direction, the detecting elements configured to detect X-rays transmitted through the object;   a controller configured to perform a multi-helical scan using said an X-ray tube device and said detector to acquire projection data;   a data extending unit configured to generate, using replication of the projection data, reconstruction projection data corresponding to an extension region located outside a region in which the detecting elements are arranged; and   a reconstructing unit configured to reconstruct a tomographic image based on the reconstruction projection data using a cone-beam reconstruction method.   
     
     
       33. An X-ray computerized tomographic apparatus, comprising:
 an X-ray tube device configured to irradiate an object with an X-ray beam;   a detector having a plurality of detecting elements arrayed in a slice direction, the detecting elements configured to detect X-rays transmitted through the object;   a controller configured to perform a multi-helical scan using said an X-ray tube device and said detector to acquire projection data;   a data extending unit configured to generate, using extrapolation of the projection data, reconstruction projection data corresponding to an extension region located outside a region in which the detecting elements are arranged; and   a reconstructing unit configured to reconstruct a tomographic image based on the reconstruction projection data using a cone-beam reconstruction method.   
     
     
       34. An apparatus according to claim 33, wherein said data extending unit is configured to generate reconstruction projection data corresponding to an extension region located in the slice direction outside the region in which the detecting elements are arranged. 
     
     
       35. An X-ray computerized tomographic apparatus, comprising:
 an X-ray tube device configured to irradiate an object with an X-ray beam;   a detector having a plurality of detecting elements arrayed in a slice direction, the detecting elements configured to detect X-rays transmitted through the object;   a controller configured to perform a multi-helical scan using said an X-ray tube device and said detector to acquire projection data;   a calculator configured to calculate, based on the projection data, reconstruction projection data calculated so that a helical pitch is unrestricted by a set field of view; and   a reconstructing unit configured to reconstruct a tomographic image based on the reconstruction projection data using a cone-beam reconstruction method.   
     
     
       36. A method of producing a tomographic image of an object, comprising:
 obtaining projection data by irradiating the object with an X-ray beam in a multi-helical scan and detecting X-rays transmitted through the object using a detector having a plurality of detecting elements arrayed in a slice direction;   calculating, based on the projection data, reconstruction projection data corresponding to an extension region located outside a region in the slice direction in which the detecting elements are arranged; and   reconstructing the tomographic image based on the calculated reconstruction projection data using a cone-beam reconstruction method.   
     
     
       37. A method of producing a tomographic image of an object, comprising:
 obtaining projection data by irradiating the object with an X-ray beam in a multi-helical scan and detecting X-rays transmitted through the object using a detector having a plurality of detecting elements arrayed in a slice direction;   applying at least one weighting factor to the obtained projection data to compensate for insufficient or unavailable projection data corresponding to a region of said object; and   reconstructing the tomographic image in the region based on the weighted projection data using a cone beam reconstruction method.   
     
     
       38. A method of producing a tomographic image of an object, comprising:
 obtaining projection data by irradiating the object with an X-ray beam in a multi-helical scan and detecting X-rays transmitted through the object using a detector having a plurality of detecting elements arrayed in a slice direction;   calculating, using replication of the obtained projection data, reconstruction projection data corresponding to an extension region located outside a region in the slice direction in which the detecting elements are arranged; and   reconstructing the tomographic image based on the calculated reconstruction projection data using a cone-beam reconstruction method.   
     
     
       39. A method of producing a tomographic image of an object, comprising:
 obtaining projection data by irradiating the object with an X-ray beam in a multi-helical scan and detecting X-rays transmitted through the object using a detector having a plurality of detecting elements arrayed in a slice direction;   calculating, using extrapolation of the obtained projection data, reconstruction projection data corresponding to an extension region located outside a region in the slice direction in which the detecting elements are arranged; and   reconstructing the tomographic image based on the calculated reconstruction projection data using a cone-beam reconstruction method.   
     
     
       40. A method of producing a tomographic image of an object, comprising:
 obtaining projection data by irradiating the object with an X-ray beam in a multi-helical scan and detecting X-rays transmitted through the object using a detector having a plurality of detecting elements arrayed in a slice direction;   calculating, based on the obtained projection data, reconstruction projection data calculated so that a helical pitch is unrestricted by a set field of view; and   reconstructing the tomographic image based on the calculated reconstruction projection data using a cone-beam reconstruction method.