Anti-scatter grids and collimator designs, and their motion, fabrication and assembly

• US 6,987,836 B2
• Filed: 02/01/2002
• Issued: 01/17/2006
• Est. Priority Date: 02/01/2001
• Status: Active Grant

• Current Assignee: Creatv Microtech, Inc. (Thermo Fisher Scientific Incorporated)
• Original Assignee: Creatv Microtech, Inc. (Thermo Fisher Scientific Incorporated)
• Inventors: Tang, Cha-Mei, Makarova, Olga V.
• Primary Examiner(s): Glick, Edward J.
• Assistant Examiner(s): Kiknadze, Irakli
• Application Number:
  US10/060,399
• Publication Number:
  US 20030026386A1
• Time in Patent Office: 1,446 Days
• Field of Search: 378/154, 378/147, 378/155, 378/150, 378/149, 378/148, 378/34, 378/35, 250/505.1, 250/263.1, 430/5, 264/279.1
• US Class Current: 378/154
• CPC Class Codes: G21K 1/025 using multiple collimators, e.g. Bucky screens; other devices for eliminating undesired or dispersed radiation

Abstract

Grids and collimators, for use with electromagnetic energy emitting devices, include at least a metal layer that is formed, for example, by electroplating/electroforming or casting. The metal layer includes top and bottom surfaces, and a plurality of solid integrated walls. Each of the solid integrated walls extends from the top to bottom surface and has a plurality of side surfaces. The side surfaces of the solid integrated walls are arranged to define a plurality of openings extending entirely through the layer. At least some of the walls also can include projections extending into the respective openings formed by the walls. The projections can be of various shapes and sizes, and are arranged so that a total amount of wall material intersected by a line propagating in a direction along an edge of the grid is substantially the same as another total amount of wall material intersected by another line propagating in another direction substantially parallel to the edge of the grid at any distance from the edge. Methods to fabricate these grids using copper, lead, nickel, gold, any other electroplating/electroforming materials or low melting temperature metals are described.

Claims

1. A method for manufacturing at least a portion of a grid or collimator with at least some non-parallel walls orientation, having at least one layer comprising a plurality of walls defining openings therein, and being adaptable for use with an electromagnetic energy emitting device that generates a sheet x-ray beam with the long dimension in the x-direction and the short dimension in the y-dimension propagating in the z-direction, the method comprising the steps of:

attaching a photoresist material onto a substrate;

covering the photoresist with a mask having a plurality of aperture therein;

irradiating parallel sheet beam of x-rays of energy onto the first mask, such that some of the rays of energy enter at least some of the apertures in the first mask and strike portions of the photoresist as the first mask and photoresist/substrate assembly scans in the y-direction and the assembly forms a predetermined angle with respect to the z-direction at each y-location;

covering the photoresist with a second mask having a plurality of aperture therein;

rotating the photoresist/substrate assembly by approximately an angle θ

, in an x-y plane;

irradiating parallel sheet beam of x-rays of energy onto the second mask, such that some of the rays of energy enter at least some of the apertures in the second mask and strike portions of the photoresist as the second mask and photoresist/substrate assembly scans in the y-direction and the assembly forms a second set of predetermined angles with respect to the z-direction at each y-location;

rotating the photoresist/substrate by approximately an angle θ

/2, in an x-y plane and covering the photoresist with a third mask having a plurality of aperture therein to form corners of the focused grid or collimator;

irradiating parallel sheet beam of x-rays of energy onto the third mask, such that some of the rays of energy enter at least some of the apertures in the third mask and strike portions of the photoresist as the third mask and photoresist/substrate assembly scans in the y-direction and the assembly forms a third set of predetermined angles with respect to the z-direction at each y-location;

removing portions of said photoresist material to create openings in said photoresist material exposing areas of said substrate; and

placing septal wall material in said openings in said photoresist material on said exposed areas of said substrate.

2. The method as claimed in claim 1, wherein said some of the rays enter at least some of the apertures in the mask at an entering angle other than 0°

with respect to a front surface of the mask.

3. The method as claimed in claim 1, wherein said removing includes using a developing solution to remove said portions of said photoresist material before placing the septal wall material.

4. The method as claimed in claim 1, further comprising:

removing said substrate from said material.

5. The method as claimed in claim 1, wherein said substrate removing step removes said substrate from said material by abrasion.

6. The method as claimed in claim 1, further comprising:

removing remaining portions of said photoresist material from said grid after placing the wall material.

7. The method as claimed in claim 1, wherein:

said photoresist material includes a positive photoresist; and

wherein the method further comprises removing said portions of said photoresist material exposed to beam of ray of energy in a positive photoresist developing solution.

8. The method as claimed in claim 1, wherein:

said photoresist material includes a negative photoresist; and

wherein the method further comprises removing said portions of said photoresist material unexposed to beams of ray of energy in negative photoresist developing solution.

9. The method as claimed in claim 1, wherein said wall material placing step includes electroforming said material on said exposed areas of said substrate.

10. The method as claimed in claim 1, wherein said wall material placing step includes electroplating said material on said exposed areas of said substrate.

11. The method as claimed in claim 10, wherein said wall material includes at least one of the following:

nickel, nickel-iron, copper, silver, gold, lead, tungsten, uranium, or any other common electroplating/electroforming or casting materials.

12. The method as claimed in claim 1, further comprising:

forming a plurality of said layers by performing said steps recited in claim 1 to form each said layer; and

stacking said layers to form said grid.

13. The method as claimed in claim 1, wherein said substrate base material includes a graphite substrate.

14. The method as claimed in claim 1, wherein said substrate base material includes a silicon substrate coated with a plating base.

15. The method as claimed in claim 1, further comprising:

forming a plurality of said portion of a grid or collimator by performing said steps recited in claim 1 to form each said portion of a grid or collimator; and

assembling said portions of a grid or collimator to form a said layer of a said grid or collimator.

16. The method as claimed in claim 1, further comprising:

repeating the steps of covering of the mask, irradiation of rays of energy and removing at least a portion of the mask a number of appropriate times.

17. The method as claimed in claim 1, the angle of rotation θ

of the substrate is approximately 90 degrees.

18. The method as claimed in claim 1, wherein the orientation of some of the walls is focused to a line.

19. The method as claimed in claim 1, wherein the focal distance of some parts of the wall is different than the focal distance at other walls.

20. The method as claimed in claim 1, wherein the orientation of some of the walls is focused to a different line than the orientation of other parts of the walls.

21. A method of manufacturing at least a portion of an air-core grid or focused collimator, having at least one layer comprising a plurality of walls defining openings therein, and being adaptable for use with an electromagnetic energy emitting device, the method comprising the steps of:

attaching a machinable mold material onto a substrate base;

ablating portions of the machinable material to create mold openings;

placing a septa wall material in said openings in said machinable material forming septal walls of the grid or collimator;

removing substrate base material; and

removing remaining portion of said mold material from said grid or collimator.

22. The method as claimed in claim 21, wherein said machinable mold material is negative photoresist.

23. The method as claimed in claim 21, wherein the mold material is a material that can be removed.

24. The method as claimed in claim 21, wherein the substrate base material includes graphite substrate.

25. The method as claimed in claim 21, wherein the step of removing said substrate base material comprises:

abrading said base material from said at least one layer.

26. The method as claimed in claim 21, wherein the step of ablating portions of the machinable material to create mold openings comprises:

ablating said mold material by mechanical machining.

27. The method as claimed in claim 21, wherein the step of ablating portions of the machinable material to create mold openings comprises:

ablating said mold material by laser ablation.

28. The method as claimed in claim 21, wherein the step of ablating portions of the machinable material to create mold openings comprises:

ablating said mold material by reactive ion etching.

29. The method as claimed in claim 21, wherein said wall material placing step comprises:

electroforming said material on said exposed areas of said base material.

30. The method as claimed in claim 21, wherein said wall material placing step comprises:

electroplating said material on said exposed areas of said base material.

31. The method as claimed in claim 21, wherein said wall material includes at least one of the following:

nickel-iron, copper, silver, gold, lead, tungsten, uranium, or any other common electroplating/electroforming or casting materials.

32. The method as claimed in claim 21, where said wall material includes casting.

33. The method as claimed in claim 21, further comprising:

forming a plurality of said layers by performing said steps recited in claim 21 to form each said layer; and

stacking said layers to form said grid.

34. The method as claimed in claim 21, further comprising:

forming a plurality of said layers by performing said steps recited in claim 21 to form each said layer; and

assembling said layers to form said grid.

35. The method as claimed in claim 21, further comprising the steps of:

repeating said steps of ablating portions of the machinable material to create openings and placing a septa wall material in said openings in said machinable material forming septal walls of the grid or collimator prior to removal of the mold and substrate.

36. The method as claimed in claim 21, wherein the orientation of some of the walls is focused to a line.

37. The method as claimed in claim 21, wherein the focal distance of parts of the wall is different than the focal distance at other parts of the wall.

38. The method as claimed in claim 21, wherein the orientation of some of the walls is focused to a different line than the orientation of other walls.