Positional adjustment of resolution in radiation CT scanner

• US 5,386,446 A
• Filed: 07/06/1993
• Issued: 01/31/1995
• Est. Priority Date: 07/06/1992
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Manabe, Yoshinori, Fujimoto, Hideki
• Primary Examiner(s): Porta, David P.
• Application Number:
  US08/086,206
• Time in Patent Office: 574 Days
• Field of Search: 378/4, 378/8, 378/11, 378/15, 378/16, 378/19, 378/20, 378/110, 378/112, 378/150-153
• US Class Current: 378/20
• CPC Class Codes: A61B 6/027 characterised by the use of a particular data acquisition trajectory, e.g. helical or spiral
• CPC Class Codes: A61B 6/032 Transmission computed tomography [CT]
• CPC Class Codes: A61B 6/0487 Motor-assisted positioning
• CPC Class Codes: A61B 6/06 Diaphragms

Abstract

There provided is a radiation computed tomography (CT) scanner, such as an X-ray CT scaner. A CT image of an object is obtained, resolution of the CT image being affected by a resolution adjustment parameter and the object having an axis. In case of an X-ray CT scaner, the scanner comprises a couch having a longitudinal direction, the axis of the object being aligned along the longitudinal direction, an X-ray source for radiating X-rays toward the object, a detector for detecting the X-rays transmitted through the object, an element for rotating at least the X-ray source around the object, an element for at least relatively moving the X-rays in the longitudinal direction, and an element for controlling the resolution adjustment parameter. Slit members may further be provided for forming the X-rays into a given slice thickness. The parameter includes moving pitches of the couch and rotating element, a rotating speed of the rotating element, an amount of X-rays, and slit widths, according to a longitudinal position of the object.

Claims

1. A radiation computed tomography scanner by which a computed tomography image of an object to be examined is obtained by a helical scan, resolution of the computed tomography image being affected by a resolution adjustment parameter, the scanner comprising:

a couch for supporting the object having a body axis, said object being examined along a direction of the body axis;

a radiation source for emitting radiation toward the object laid on the couch so that the radiation is transmitted through the object;

means for detecting the radiation transmitted through the object;

means for driving the radiation source and the couch which are relatively rotatable with respect to each other and relatively linearly movable with respect to each other along the direction of the body axis in order to perform the helical scan; and

means for controlling the resolution adjustment parameter simultaneously with performing the helical scan.

2. The scanner according to claim 1, wherein said couch has a tabletop on which the object is laid, the tabletop representing a longitudinal direction along which the direction of the body axis is aligned and being movable along the longitudinal direction.

3. The scanner according to claim 2, wherein said driving means comprises means for rotating the radiation source and the detecting means together along a circular locus around the object and means for moving the tabletop in the longitudinal direction while the radiation source and the detecting means are rotated together by the rotating means.

4. The scanner according to claim 3, further comprising a slit means, which has an adjustable slit width, for projecting the radiation as a slice thickness in the longitudinal direction.

5. The scanner according to claim 4, wherein said resolution adjustment parameter comprises at least one of a moving pitch of the tabletop, the slit width of the slit means, an amount of radiation emitted from the radiation source, and a rotating speed of the radiation source and the detecting means.

6. The scanner according to claim 5, wherein said slit means has two slit members having adjustable slit widths, respectively, one slit member being arranged between the radiation source and the object and the other slit member being arranged between the object and the detecting means.

7. The scanner according to claim 6, wherein said radiation source is an X-ray tube for emitting X-rays.

8. The scanner according to claim 3, wherein said resolution adjustment parameter comprises at least one of a moving pitch of the tabletop in the longitudinal direction, an amount of radiation emitted from the radiation source, and a rotating speed of the radiation source and the detecting means.

9. The scanner according to claim 8, wherein said radiation source comprises an X-ray tube which emits X-rays.

10. The scanner according to claim 8, wherein said controlling means comprises means for measuring a time corresponding to a position of the tabletop in the longitudinal direction and means for changing the resolution adjustment parameter in response to the time measured by the time measuring means.

11. The scanner according to claim 8, wherein said controlling means comprises a detector for detecting a position of the tabletop in the longitudinal direction and means for changing the resolution adjustment parameter in response to the position of the tabletop detected by the detector.

12. The scanner according to claim 11, further comprising means for programming the helical scan which has a selecting means for selecting the resolution adjustment parameter manually for each of a plurality of positions of the tabletop in the longitudinal direction, the selected adjustment parameter being output to the changing means.

13. The scanner according to claim 12, further comprising means for obtaining data of a scanography image of the object, the data of the scanography image being supplied to the programming means, wherein said programming means includes a display means which displays the scanography image which is used in the selection of the resolution adjustment parameter.

14. The scanner according to claim 13, wherein said programing means has an input means for manually inputting a scan range in the longitudinal direction and the selecting means includes means for selecting the resolution adjustment parameter within the scan range.

15. The scanner according to claim 14, wherein said programming means has a further input means for manually specifying a range corresponding to a region of interest within the scan range on the scanography image displayed on the display means and said selecting means has an additional means for assigning the range of the resolution adjustment parameter of a higher resolution grade than an outer limit of the range in the longitudinal direction.