Method and apparatus for performing computed tomography

• US 20060056577A1
• Filed: 09/14/2004
• Published: 03/16/2006
• Est. Priority Date: 09/14/2004
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Oho, Shigeru, Hunt, Frank, Sasaki, Kaname
• Granted Patent: US 7,254,211 B2
• Time in Patent Office: Days
• US Class Current: 378/4
• CPC Class Codes: A61B 6/4458 the source unit or the detector unit being attached to robotic arms
• CPC Class Codes: G01N 2223/419 computed tomograph
• CPC Class Codes: G01N 23/046 using tomography, e.g. computed tomography [CT]

Abstract

An apparatus for performing computed tomography having a radiation source and at least one radiation detector spaced from the radiation source and which generates an output signal representative of the strength of the received radiation from the radiation source. A part support for holding a plurality of parts is positioned in between the radiation source and the detectors. The part support is rotatably mounted about an axis generally perpendicular to a vector between the radiation source and the detectors so that, upon rotation of the part support, the radiation detectors generate an output signal corresponding to the internal structure of parts supported on the part support. A computer system receives the output signals from the detectors and, under program control, generates a report of the internal structure of the parts on the part support.

Claims

1. System for performing computed tomography comprising:

a radiation source;

at least one radiation detector spaced from said radiation source, said at least one detector generating an output signal representative of the strength of received radiation from the radiation source;

a table which supports a plurality of parts positioned between said radiation source and said at least one detector;

at least one said table and said radiation source being movable relative to the other and said at least one detector; and

a processor which receives said output signal from said at least one detector as an input signal and, under program control, generates an output representative of at least a portion of the internal structure of parts supported on the table.

2. The invention as defined in claim 1 wherein said table comprises a container into which parts are placed.

3. The invention as defined in claim 1 wherein said table comprises a rotary table, said table being positioned on said rotary table, and an actuator which rotates said table about a predetermined axis.

4. The invention as defined in claim 3 wherein said table axis is substantially perpendicular to a vector between said radiation source and said detectors.

5. The invention as defined in claim 4 and comprising a second actuator which moves the table a predetermined increment in the direction of said table axis per revolution of said table.

6. The invention as defined in claim 1 wherein said computer system is programmed to disregard output signals from said detectors corresponding to said table.

7. The invention as defined in claim 1 wherein said computer system is programmed to reconstruct an image of the internal structure of only a portion of each workpiece.

8. The invention as defined in claim 2 and comprising a marker attached to said container at a predetermined position relative to parts contained in the container.

9. The invention as defined in claim 8 wherein said container contains a plurality of partitions which divide the interior of the container into a plurality of parts containing compartments.

10. The invention as defined in claim 1 and comprising a plurality of radiation detectors, wherein said radiation detectors are arranged in an arc centered about said radiation source.

11. The invention as defined in claim 10 wherein said radiation detectors are arrayed in a two-dimensional array.

12. The invention as defined in claim 1 wherein the parts are constructed at least partially of metal.

13. System for performing computed tomography comprising:

a radiation source;

at least one radiation detector which generates an output signal representative of the strength of received radiation from the radiation source;

a robotic arm having at least one degree of movement, said radiation source and said at least one radiation detector being mounted to said robotic arm;

said robotic arm being programmed to move along said at least one degree of movement so that at least a portion of a part under examination is positioned between said radiation source and said at least one radiation detector; and

a computer system which receives said output signal from said at least one detector as an input signal and, under program control, generates an image of the internal structure of the portion of the part under examination.

14. The invention as defined in claim 13 wherein the part is constructed at least partially of metal.

15. A method for performing computed tomography on a plurality of parts using a rotating table positioned between a radiation source and a plurality of radiation detectors, said plurality of detectors producing an output signal representative of the strength of the radiation received by the detectors, comprising the steps of:

collecting data for the radiation detectors responsive to the plurality of parts during revolution of the table for each revolution of the table; and

reconstructing from the collected data an output representative of at least a portion of the internal structure of at least a portion of the parts supported on the table.

16. The method as defined in claim 15 wherein said reconstructing step further comprises the steps of identifying adjacent areas corresponding to voids and merging said identified areas together.

17. The method as defined in claim 15 wherein the axis of the table is substantially perpendicular to a vector between the radiation source and the at least one radiation detectors, and further comprising the step of moving the table a predetermined increment along the axis per revolution of the table.

18. The method as defined in claim 15 and comprising the step of disregarding data from the detector for portions of the part other than said at least one portion of the part.

19. The method as defined in claim 18 wherein said parts are contained in a container having partitions, and wherein said disregarding step comprises the step of disregarding data corresponding to the partitions.

20. The method as defined in claim 15 and comprising the steps of gathering data representative of the structure of an empty table from the detectors during at least one revolution of the table, and wherein said reconstructing step comprises the step of subtracting said gathered table data from said collected data.

21. The method as defined in claim 15 wherein the part is constructed at least partially of metal.

22. A method for performing computed tomography on parts using a rotating table positioned between a radiation source and a plurality of radiation detectors, said plurality of detectors producing an output signal representative of the strength of the radiation received by the detectors, comprising the steps of:

collecting data from the at least one radiation detector during revolution of the table for each revolution of the table only for a predetermined portion of the part; and

reconstructing from the collected data an output representative of the internal structure of the predetermined portion of the part mounted on the table.

23. The method as defined in claim 22 wherein said at least one part is mounted in a container having partitions, and further comprising the steps of:

modifying the collected data to eliminate data corresponding to partitions; and

reconstructing from the modified collected data an image of the internal structure of the parts in the container.

24. The method as defined in claim 22 wherein said reconstructing step further comprises the step of forming an image representative of the internal structure of the part.

25. The method as defined in claim 24 wherein said image forming step includes the step of using different colors in the image for different part densities.