Section reconstruction method and radiographic apparatus

• US 6,577,701 B2
• Filed: 07/22/2002
• Issued: 06/10/2003
• Est. Priority Date: 07/30/2001
• Status: Expired due to Fees

• Current Assignee: Shimadzu Corporation
• Original Assignee: Shimadzu Corporation
• Inventors: Onishi, Shuhei, Kishi, Taketo, Shintani, Eiichi, Ukita, Masaaki
• Primary Examiner(s): Bruce, David V.
• Application Number:
  US10/199,067
• Publication Number:
  US 20030021373A1
• Time in Patent Office: 323 Days
• Field of Search: 378/4, 378/8, 378/15, 378/19, 378/901
• US Class Current: 378/4
• CPC Class Codes: A61B 6/032 Transmission computed tomography [CT]
• CPC Class Codes: G06T 3/4007 based on interpolation, e.g. bilinear interpolation image demosaicing G06T3/4015; edge-driven or edge-based scaling G06T3/403
• CPC Class Codes: Y10S 378/901 Computer tomography program or processor

Abstract

An X-ray tube (X-ray focus) and an X-ray detector opposed to each other across an object synchronously scan the object to acquire radiographic data in each scan position. A section reconstruction method is provided in which the radiographic data or data resulting from a filtering process of the radiographic data is projected as back projection data back to a two-dimensional or three-dimensional reconstruction area virtually set to a region of interest of the object. Enlarged interpolation data is generated by interpolating the back projection data and then the enlarged interpolation data is projected back to the reconstruction area without interpolation. The number of interpolation computations is reduced to an amount corresponding to the enlargement by interpolation of the back projection data, to shorten the reconstruction computation time.

Claims

1. A section reconstruction method for projecting radiographic data of an object acquired in each scan position back to a section reconstruction area, said method comprising the step of:

generating enlarged interpolation data by interpolating back projection data and then projecting said enlarged interpolation data back to a two-dimensional or three-dimensional reconstruction area virtually set to a region of interest of said object, said back projection data being radiographic data, or data resulting from filtering of said radiographic data, said radiographic data being acquired in each scan position by causing a radiation source and a detector arranged opposite each other across said object to scan said object synchronously, or to scan said object synchronously with rotation of said object, said radiation source irradiating said object with electromagnetic waves capable of penetrating said object, said detector detecting electromagnetic waves transmitted through said object.

2. A section reconstruction method as defined in claim 1, wherein said enlarged interpolation data is generated by an enlargement-rate set to an integer or decimal of at least 1.0.

3. A section reconstruction method as defined in claim 1, wherein said enlarged interpolation data is generated by an enlargement-rate set to at least four times.

4. A section reconstruction method as defined in claim 1, wherein, when said reconstruction area is an enlarged reconstruction area subdivided to have pixel density exceeding a detector pixel density, said enlarged interpolation data is generated by an enlargement-rate variable in proportion to an enlargement-rate of an enlarged reconstruction.

5. A section reconstruction method as defined in claim 1, wherein, when a three-dimensional reconstruction is performed for projecting two-dimensional back projection data to the three-dimensional reconstruction area, two-dimensional enlarged interpolation data is generated by interpolating said two-dimensional back projection data, and said two-dimensional enlarged interpolation data is projected back to said three-dimensional reconstruction area.

6. A section reconstruction method as defined in claim 1, wherein said back projection data is enlarged by interpolation by an enlargement-rate variable with directions of back projection.

7. A section reconstruction method as defined in claim 1, wherein, when said reconstruction area is a reduced reconstruction area reduced to have pixel density less than a detector pixel density, average interpolation data generated by interpolation after taking a moving average of said back projection data is projected back to said reduced reconstruction area.

8. A section reconstruction apparatus for projecting radiographic data of an object acquired in each scan position back to a reconstruction area, said apparatus comprising:

a radiation source for irradiating said object with electromagnetic waves capable of penetrating said object;

a detector for detecting electromagnetic waves transmitted through said object; and

image processing means for generating enlarged interpolation data by interpolating back projection data and then projecting said enlarged interpolation data back to a two-dimensional or three-dimensional reconstruction area virtually set to a region of interest of said object, said back projection data being radiographic data, or data resulting from filtering of said radiographic data, said radiographic data being acquired in each scan position by causing said radiation source and said detector arranged opposite each other across said object to scan said object synchronously, or to scan said object synchronously with rotation of said object.

9. A section reconstruction apparatus as defined in claim 8, wherein said enlarged interpolation data is generated by an enlargement-rate set to an integer or decimal of at least 1.0.

10. A section reconstruction apparatus as defined in claim 8, wherein said enlarged interpolation data is generated by an enlargement-rate set to at least four times.

11. A section reconstruction apparatus as defined in claim 8, wherein, when said reconstruction area is an enlarged reconstruction area subdivided to have pixel density exceeding a detector pixel density, said enlarged interpolation data is generated by an enlargement-rate variable in proportion to an enlargement-rate of an enlarged reconstruction.

12. A section reconstruction apparatus as defined in claim 8, wherein, when a three-dimensional reconstruction is performed for projecting two-dimensional back projection data to the three-dimensional reconstruction area, two-dimensional enlarged interpolation data is generated by interpolating said two-dimensional back projection data, and said two-dimensional enlarged interpolation data is projected back to said three-dimensional reconstruction area.

13. A section reconstruction apparatus as defined in claim 8, wherein said back projection data is enlarged by interpolation by an enlargement-rate variable with directions of back projection.

14. A section reconstruction apparatus as defined in claim 8, wherein, when said reconstruction area is a reduced reconstruction area reduced to have pixel density less than a detector pixel density, average interpolation data generated by interpolation after taking a moving average of said back projection data is projected back to said reduced reconstruction area.