X-ray filter having dynamically displaceable x-ray attenuating fluid

• US 7,308,073 B2
• Filed: 10/20/2005
• Issued: 12/11/2007
• Est. Priority Date: 10/20/2005
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Tkaczyk, J. Eric, Walter, Deborah J., Wu, Xiaoye, Du, Yanfeng, Bales, Brian C., Leblanc, James W.
• Primary Examiner(s): Ho, Allen C.
• Application Number:
  US11/163,496
• Publication Number:
  US 20070092066A1
• Time in Patent Office: 782 Days
• Field of Search: 378/5, 378/16, 378/145, 378/147, 378/150, 378/151, 378/156, 378/157, 378/158, 378/159
• US Class Current: 378/16
• CPC Class Codes: G21K 1/10 Scattering devices; Absorbing devices; Ionising radiation filters

Abstract

A bowtie filter is constructed to have a fluidic envelope filled with attenuating fluid and a displacement insert that can present various x-ray attenuation profiles during a scan. The insert is designed to displace the attenuating fluid to achieve a denied attenuating or filtering profile. The insert can be rotated, twisted, moved, and otherwise contorted within the fluidic envelope as needed during the course of a scan. As the angle, position and shape of the zombie is changed, the x-ray profile of the filter changes. The insert may have a default shape when at rest, but can have its shape changed when external forces are placed thereon. As x-ray filtering needs change during the course of the scan, the insert can be compressed, stretched, and/or contorted to achieve additional filtering profiles.

Claims

1. An x-ray attenuating filter comprising:

an envelope containing x-ray attenuating fluid;

a fluid displacement device disposed within the envelope and configured to displace the x-ray attenuating fluid, the fluid displacement device having a shell having one of foam or air sealing disposed therein;

an actuator; and

wherein the shell is operable connected to the actuator at one end and connected to a fixed point at another end and wherein the actuator is configured to rotate the one end relative to the fixed point to re-shape the shell.

2. The filter of claim 1 wherein the shell is operable connected to the actuator at one end and connected to a fixed point at another end, and wherein the actuator is configured to translate the one end at least one of toward or away from the fixed point to re-shape the shell.

3. The filter of claim 1 wherein the fluid displacement device has a frustoconical shape.

4. The filter of claim 1 wherein the fluid displacement device has a complex, noncylindrical shape being non-uniformed around a three dimensional axis.

5. The filter of claim 1 wherein the fluid displacement device has a shape of geometric proportions similar to the object to be scanned.

6. The filter of claim 1 wherein the x-ray attenuating fluid includes of one liquid metal or high-density powder suspended in a non-settling colloidal suspension.

7. The x-ray filter of claim 6 wherein high-density powder suspended in a non-settling colloidal suspension includes Na₂WO₄ in a solution of water, oil, organic liquid, or non-organic liquid.

8. The filter of claim 1 wherein the envelope has a general bowtie shape.

9. The filter of claim 1 wherein the fluid displacement device is configured to be at least one rotated or translated during an active radiographic scan.

10. The x-ray filter, of claim 1 wherein the x-ray attenuating fluid is at least one of:

liquid metal;

nanoparticles suspended in a non-settling solution;

or

a compound with pH control buffer dissolved in a liquid.

11. The x-ray filter of claim 10 wherein the liquid metal includes liquid mercury, wherein nanoparticles include high density powder, wherein the non-settling solution is a colloidal suspension, and wherein the compound includes salt.

12. The x-ray filter of claim 10 wherein the nanoparticles include tungsten oxide.

13. The filter of claim 1 wherein the shell is formed of pliable material.

14. The filter of claim 13 wherein the pliable material includes a viscoelastic material.

15. A CT system comprising an x-ray source, an x-ray detector, and an x-ray filter assembly disposed between the x-ray detector and the x-ray source along a path of irradiation, the x-ray filter assembly having:

a bowtie filter having a body with an x-ray attenuating fluid disposed therein;

an x-ray attenuating fluid displacement device sealingly enclosed within the body of the bowtie filter; and

a mechanized actuator connected to the x-ray attenuating fluid displacement device to dynamically position the attenuating fluid displacement device within the body of the bowtie filter to define a desired filtering profile for the bowtie filter.

16. The system of claim 15 wherein the mechanized actuator includes a motor connected to the x-ray attenuating fluid displacement device by a rotatable shaft, the rotatable shaft configured to rotate the attenuating displacement device.

17. The system of claim 15 wherein the mechanized actuator includes a motion controller connected to the x-ray attenuating fluid device by a first rotor shaft disposed concentrically within a second rotor shaft, the first rotor shaft designed to contort the attenuating fluid displacement device and the second rotor shaft designed to rotate the attenuating fluid displacement device.

18. The system of claim 15 wherein the mechanized actuator is designed to at least one of compress, stretch, or twist the x-ray attenuating fluid displacement device to a desired 3D shape.

19. The system of claim 15 wherein the x-ray attenuating fluid displacement device has an elastomeric shell with one of air or foam disposed therein.

20. The system of claim 15 wherein the x-ray attenuating fluid includes alkali halide salts in water.