Method for X-ray fluoroscopy or radiography, and X-ray apparatus

• US 5,598,453 A
• Filed: 08/22/1995
• Issued: 01/28/1997
• Est. Priority Date: 08/30/1994
• Status: Expired due to Fees

• Current Assignee: Hitachi Medical Corporation (Hitachi, Ltd.)
• Original Assignee: Hitachi Medical Corporation (Hitachi, Ltd.)
• Inventors: Ueki, Hironori, Baba, Rika, Ueda, Ken, Sekihara, Kensuke, Umetani, Keiji
• Primary Examiner(s): WONG, DON KITSUN
• Application Number:
  US08/517,852
• Time in Patent Office: 525 Days
• Field of Search: 378/4, 378/146, 378/193, 378/195, 378/196, 378/197, 378/198, 378/208, 378/15, 378/20, 378/62
• US Class Current: 378/146
• CPC Class Codes: A61B 6/032 Transmission computed tomography [CT]
• CPC Class Codes: A61B 6/0487 Motor-assisted positioning

Abstract

An X-ray apparatus for collecting X-ray transmission data of a subject from a plurality of directions to generate an X-ray transmission image or X-ray CT image of the subject, which includes an X-ray generator for generating an X-ray, an X-ray detector for detecting a transmission X-ray after the X-ray generated by the X-ray generator is transmitted through the subject, a rotation unit for rotating an imaging unit including the X-ray generator and the X-ray detector around the subject, a data collector for converting an output signal of the X-ray detector to a digital signal and collecting the digital signal, a signal processor for subjecting data collected by the data collector to a signal processing operation, a display for displaying thereon as an image the data collected by the data collector and the data subjected by the signal processor to the signal processing operation, and a position change unit for moving a relative position of a rotation center of the imaging unit and the subject in a direction parallel to a rotation plane of the rotation, and wherein the imaging unit is rotated by the rotator around the subject and at the same time the relative position is changed by the position change unit in a direction parallel to the rotation plane to perform X-ray fluoroscopic or radiographic operation or CT scan.

Claims

1. A fluoroscopic or radiographic method or CT scan method in which a pair of an X-ray source and an X-ray detector opposed to the X-ray source is rotated on a circular orbit and at the same time a subject is moved parallelly with respect to a rotation plane of said pair to perform X-ray fluoroscopic or radiographic operation or CT scan.

2. A fluoroscopic or radiographic method or CT scan method as set forth in claim 1, wherein the movement of said subject is periodical reciprocating movement on a straight line parallel to said rotation plane, and a period of said reciprocating movement coincides with a period of rotation of the pair of said X-ray source and said X-ray detector.

3. A fluoroscopic or radiographic method or CT scan method in which a pair of an X-ray source and an X-ray detector opposed to the X-ray source is rotated on a circular orbit and at the same time a subject is subjected to a composite movement corresponding to a combination of a periodical reciprocating movement on a straight line parallel to a rotation plane of said pair and a vertical movement with respect to said rotation plane to perform X-ray fluoroscopic or radiographic operation or CT scan.

4. An X-ray apparatus for collecting X-ray transmission data of a subject from a plurality of directions to generate an X-ray transmission image or X-ray CT image of said subject, comprising:

X-ray generation means for generating an X-ray;

X-ray detection means for detecting a transmission X ray after the X-ray generated by said X-ray generation means is transmitted through said subject;

rotation means for rotating an imaging unit including said X-ray generation means and said X-ray detection means around said subject;

data collection means for converting an output signal of said X-ray detection means to a digital signal and collecting said digital signal;

signal processing means for subjecting data collected by said data collection means to a signal processing operation;

image display means for displaying thereon as an image the data collected by said data collection means and the data subjected by said signal processing means to the signal processing operation; and

position change means for moving a relative position of a rotation center of said imaging unit and said subject in a direction parallel to a rotation plane of said rotation,

wherein said imaging unit is rotated by said rotation means around said subject and at the same time said relative position is changed by said position change means in a direction parallel to said rotation plane to perform X-ray fluoroscopic or radiographic operation or CT scan.

5. An X-ray apparatus as set forth in claim 4, wherein said position change means has a function of changing said relative position of the rotation center of said imaging unit and the subject in a direction parallel to said rotation plane and in a direction vertical to said rotation plane, said imaging unit is rotated by said rotation means around said subject and at the same time, the relative position of said rotation center and said subject is changed by said position change means in said directions parallel and vertical to said rotation plane to perform X-ray fluoroscopic or radiographic operation or CT scan.

6. An X-ray apparatus as set forth in claim 4, further comprising a bed board for limiting a part of said subject to be subjected to the X-ray fluoroscopic or radiographic operation or CT scan, means for performing a reciprocating movement over said bed board on a straight line parallel to said rotation plane, and means for causing a period of said reciprocating movement to coincide a rotation period of said imaging unit.

7. An X-ray apparatus as set forth in claim 6, further comprising control means, when said X-ray generation means is located at a point-symmetric position with respect to said rotation center during the rotation of said imaging unit, for controlling a position of said bed board to be located at a point-symmetric position with respect to a middle point of said reciprocating movement, and when said X-ray generation means is located at a line-symmetric position with respect to a straight line passing through the rotation center, parallel to the rotation plane and vertical to said reciprocating movement direction, for controlling said bed position to be located at a point-symmetric position with respect to said middle point of the reciprocating movement.

8. An X-ray apparatus as set forth in claim 6, further comprising control means, at the same time said imaging unit is rotated by one turn along a circular orbit from a horizontal position as its start point, for controlling said bed board to be horizontally reciprocated with a center position as a reciprocation start point to perform the fluoroscopic or radiographic operation or CT scan during said rotation and reciprocating movement, and at the same time said imaging unit is reversely rotated by one turn along said circular orbit after completion of said X-ray fluoroscopic or radiographic operation or CT scan, for controlling said bed board to perform the same movement as said reciprocating movement to perform the fluoroscopic or radiographic operation or CT scan during said reverse rotation and reciprocating movement.

9. An X-ray apparatus as set forth in claim 4, wherein said X-ray detection means is a 2-dimensional detector and an X-ray beam emitted from said X-ray generation means is a conical beam.

10. An X-ray apparatus as set forth in claim 4, wherein said X-ray detection means is a 2-dimensional detector, an X-ray beam emitted from said X-ray generation means is a conical beam, and said image display means for displaying said X-ray transmission image includes means for displaying with a single imaginary rotational axis parallel to a rotation axis of said imaging unit and fixed to said subject being fixed to a predetermined position on a display screen of said image display means.

11. An X-ray apparatus as set forth in claim 4, wherein said X-ray detection means is a 2-dimensional detector, an X-ray beam emitted from said X-ray generation means is a conical beam, said image display means for displaying said X-ray transmission image includes fixation means for displaying with a single imaginary rotational axis parallel to a rotation axis of said imaging unit and fixed to said subject being fixed to a predetermined position on a display screen of said image display means, and said fixation means for displaying with said imaginary rotation axis fixed to the predetermined position on said display screen includes means, when a shift in said X-ray transmission image of the subject on said display screen is not an integer value in units of an interval between pixels of a digital image indicative of said X-ray transmission image, for setting an integer value closest to said shift as said shift.

12. An X-ray apparatus as set forth in claim 4, further comprising means for subjecting said X-ray transmission data detected by said X-ray detection means to a filtering operation on a plane which includes both a straight line present on an X-ray input plane of said X-ray detection means, and parallel to said rotation plane and an X-ray generation point of said X-ray generation means in a coordinate system fixed to said imaging unit and for subjecting data after subjected to said filtering operation to a back projection with respect to a given reconstruction point of an X-ray CT image for reconstruction of the X-ray CT image of the subject.

13. An X-ray apparatus as set forth in claim 12, further comprising means for subjecting to the filtering operation said transmission X-ray data collected through a plurality of rotations of said imaging unit around said subject with use of said rotation means, for subjecting the data after subjected to said filtering operation to the back projection with respect to a given reconstruction point, and when data to be back-projected in said back projection is not measured in a rotational angle in one of said plurality of rotation turns, for performing said back projection data obtained in another rotation.

14. An X-ray apparatus as set forth in claim 12, further comprising means for subjecting to the filtering operation said transmission X-ray data collected through a plurality of rotation turns of said imaging unit around said subject with use of said rotation means, for subjecting the data after subjected to said filtering operation to the back projection with respect to a given reconstruction point, and when data to be back-projected in said back projection is within a peripheral area of the X-ray input plane of said X-ray detection means plane in a rotational angle in one of said plurality of rotations, for performing said back projection of data obtained in another rotation.

15. An X-ray apparatus as set forth in claim 12, further comprising means for making transmission X-ray data of said transmission X-ray passed through outside the X-ray input plane of said X-ray detection means and not detected by said X-ray detection means, on the imaginary expanded area of said X-ray input plane, by an extra polation method on the basis of the transmission X-ray data of said transmission X-ray detected within the view field of said X-ray input plane.

16. An X-ray apparatus as set forth in claim 12, further comprising means for subjecting to the filtering operation said transmission X-ray data collected through a plurality of rotation turns of said imaging unit around said subject with use of said rotation means, for subjecting the data after subjected to said filtering operation to the back projection with respect to a given reconstruction point, and when plurality of data to be back-projected in said back projection are present in a rotational angle in said plurality of rotations, for performing said back projection on the basis of data obtained through averaging of said plurality of data.

17. An X-ray apparatus as set forth in claim 12, further comprising means for subjecting to the filtering operation said transmission X-ray data collected through a plurality of rotation turns of said imaging unit around said subject with use of said rotation means, for subjecting the data after subjected to said filtering operation to the back projection with respect to a given reconstruction point, and when a plurality of data to be back-projected in said back projection are present in a rotational angle in said plurality of rotations, for performing said back projection on the basis of data obtained through selection of one of said plurality data.

18. An X-ray apparatus as set forth in claim 12, further comprising means for subjecting to the filtering operation said transmission X-ray data collected through a plurality of rotation turns of said imaging unit around said subject with use of said rotation means, for subjecting the data after subjected to said filtering operation to the back projection with respect to a given reconstruction point, and when a plurality of data to be back-projected in said back projection are present in a rotational angle in said plurality of rotations, for performing said back projection on the basis of data obtained through selection of one of said plurality of data of the X-ray emitted from a farmost position from said reconstruction point as an back-projection data.

19. An X-ray apparatus as set forth in claim 4, wherein said signal processing means sequentially performs the filtering operation and back-projection over said transmission X-ray data concurrently while performs the collecting operation of said transmission X-ray data by said data collection means.

20. An X-ray apparatus as set forth in claim 4, wherein said image display means sequentially displays intermediate results of the reconstruction during the reconstruction of the X-ray image of said subject by said signal processing means.

21. An X-ray apparatus for collecting X-ray transmission data of a subject from a plurality of directions to generate an X-ray transmission image or X-ray CT image of said subject, comprising:

X-ray generation means for generating an X-ray;

X-ray detection means for detecting a transmission X-ray after the X-ray generated by said X-ray generation means is transmitted through said subject;

rotation means for rotating an imaging unit including said X-ray generation means and said X-ray detection means around said subject;

data collection means for converting an output signal of said X-ray detection means to a digital signal and collecting said digital signal;

signal processing means for subjecting data collected by said data collection means to a signal processing operation;

image display means for displaying thereon as an image the data collected by said data collection means and the data subjected by said signal processing means to the signal processing operation; and

position change means for moving a relative position of a rotation center of said imaging unit and said subject at least in a direction parallel to a rotation plane of said rotation,

wherein said imaging unit is rotated by said rotation means around said subject and at the same time said relative position is changed by said position change means in a direction parallel to said rotation plane to perform X-ray fluoroscopic or radiographic operation or CT scan.