Apparatus for slit radiography

• US 4,741,012 A
• Filed: 01/23/1986
• Issued: 04/26/1988
• Est. Priority Date: 01/29/1985
• Status: Expired due to Fees

• Current Assignee: B.V. Optische Industrie "De Oude Delft"
• Original Assignee: B.V. Optische Industrie "De Oude Delft"
• Inventors: Vlasbloem, Hugo, Duinker, Simon
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Freeman, John C.
• Application Number:
  US06/821,591
• Time in Patent Office: 824 Days
• Field of Search: 378/156-158, 378/150-153, 378/145-148, 250/363 SH
• US Class Current: 378/145
• CPC Class Codes: A61B 6/06 Diaphragms
• CPC Class Codes: G21K 1/04 using variable diaphragms, shutters, choppers
• CPC Class Codes: G21K 1/10 Scattering devices; Absorbing devices; Ionising radiation filters

Abstract

An apparatus for slit radiography which comprises an X-ray source and a slit diaphragm through which a body to be examined can be scanned by a planar X-ray fan beam. The slit diaphragm is operatively associated with a plurality of juxtaposed tongue-shaped attenuation elements, which elements are arranged for having their free ends swung to a greater or lesser extent into the X-ray beam so as to effect a local attenuation of the beam. The tongue-shaped attenuation elements form at least one flared configuration as seen from the X-ray source.

Claims

1. An apparatus for slit radiography, which comprises:

an X-ray source;

a slit diaphragm for forming a planar X-ray beam;

a plurality of juxtaposed elongated attenuation elements positioned along said slit diaphragm each elongated attenuation element having a free end and having means responsive to a detector signal to enable each attenuation element to swing into said x-ray beam in respnse to said control signal, said elongated attenuation elements extending outwardly in flared configuration from said X-ray source.

2. The apparatus according to claim 1, wherein longitudinal center lines of said elongated attenuation elements intersect a bisecting plane (B) of said planar X-ray beam (B) outside of said X-ray source.

3. The apparatus according to claim 1, wherein said elongated attenuation elements are divided into groups and wherein longitudinal center lines of each group intersect a point outside said X-ray source.

4. The apparatus according to claim 1, wherein one of said elongated attenuation elements is mounted with its longitudinal center line in a bisecting plane of said planar X-ray beam.

5. The apparatus according to claim 1, wherein a width of an end of said elongated attenuation elements disposed toward said X-ray source is greater than a dimension of said X-ray source.

6. The apparatus according to claim 3, wherein said elongated attenuation elements are essentially rectangular and said longitudinal center line of each group of said elongated attenuation elements, located on either side of a centrally disposed elongated attenuation element, intersesct at a convergence point located on either side of said longitudinal center line of said centrally disposed elongated attenuation element and in a plane normal to center lines of said elongated attenuation elements, and outside a strip-like region defined by a prolongation of longitudinal sides of said centrally disposed elongated attenuation element.

7. The apparatus according to claim 1, wherein said elongated attenuation elements are essentially rectangular and wherein longitudinal center lines of said elongated attenuation elements converge in a point located in a bisecting plane of a fan angle of said planar X-ray beam on a side X-ray source remote from said elongated attenuation elements, said point being located such that prolongations of inner longitudinal sides of outermost elongated attenuation elements do not intersect at said X-ray source.

8. The apparatus according to claim 3, wherein said elongated attenuation elements are individually tapered toward said X-ray source and wherein prolongations of longitudinal sides of each group of each group of elongated attenuation elements converge at a point located outside said X-ray source in a bisecting plane of said planar X-ray beam.

9. The apparatus according to claim 1, wherein said elongated attenuation elements are divided into two groups, said elongated attenuation elements of one group alternating with said elongated attenuation elements of said other group, ends of said elongated attenuation elements of one group facing said X-ray source being disposed closer to said X-ray source than corresponding ends of said elongated attenuation elements of said other group.

10. The apparatus according to claim 9, wherein elongated attenuation elements of one of said groups are essentially rectangularly-shaped wherein elongated attenuation elements of said other group are essentially wedge-shaped and wherein longitudinal sides of adjacent wedge-shaped and rectangular elongated attenuation elements are essentially parallel.

11. The apparatus according to claim 1, wherein said elongated attenuation elements are mounted to a support in two sets wherein one set of said elongated attenuation elements being mounted so that free ends thereof are swung into said planar X-ray beam from one side of said support and said other set being mounted whereby free ends thereof are swung into said planar X-ray beam from an opposite side of said support.

12. The apparatus according to claim 11, wherein free ends of one set of elongated attenuation elements face said X-ray source and free ends of said other set of said elongated attenuation elements away from said X-ray source.

13. apparatus according to claim 1, wherein said elongated attenuation elements are mounted in a rest position outside of said slit diaphragm.

14. The apparatus according to claim 1, wherein said elongated attenuation elements in a rest position position extend partly into said planar X-ray beam to be passed through said slit diaphragm.

15. The apparatus according to claim 1, wherein said elongated attenuation elements are mounted in an enclosure including a wall formed with said slit diaphragm and wherein an X-ray pervious window is disposed across said slit diaphragm and wherein a wall of said enclosure opposite said wall including said slit diaphragm is provided with an X-ray pervious window proximate to said X-ray source.

16. The apparatus according to claim 15, wherein said elongated attenuation elements are piezoelectric strips and said enclosure is filled with an insulating fluid for preventing sparking between adjacent piezoelectric strips.

17. The apparatus according to claim 1, wherein said elongated attenuation elements are piezoelectric strips each having two lead terminals and wherein one lead terminal of each piezoelectric strip is electrically connected to like lead terminal of each other piezoelectric strip.

18. The apparatus according to claim 1, wherein said elongated attenuation elements are piezoelectric strips provided with an insulating coating.

19. The apparatus according to claim 1, wherein said elongated attenuation elements are divided into two sets extending in different planes and wherein free ends of said elongated attenuation elements extending obliquely into said planar X-ray beam.

20. The apparatus according to claim 19, wherein said elongated attenuation elements of one set are laterally staggered relative to said elongated attenuation elements of said other set.

21. The apparatus according to claim 19, wherein each set of elongated attenuation elements is mounted to a bracket means spatially disposed from one another on a common support with respect to said X-ray source.

22. The apparatus according to claim 21, wherein said common support is provided with means for adjusting position of said common support relative to said slit diaphragm.

23. The apparatus according to claim 21, wherein said elongated attenuation elements are piezoelectric strips and wherein said common support is provided with a connector for application of electrical signals to said piezoelectric strips.

24. The apparatus according to claim 4 wherein there is provided an odd number of elongated attenuation elements.