Imaging with focused curved radiation detectors

• US 4,709,382 A
• Filed: 11/21/1984
• Issued: 11/24/1987
• Est. Priority Date: 11/21/1984
• Status: Expired due to Fees

• Current Assignee: Picker International, Inc. (Marconi Holdings Company Limited)
• Original Assignee: Picker International, Inc. (Marconi Holdings Company Limited)
• Inventors: Sones, Richard A.
• Primary Examiner(s): Howell, Janice A.
• Assistant Examiner(s): Hannaher, Constantine
• Application Number:
  US06/673,779
• Time in Patent Office: 1,098 Days
• Field of Search: 378/5, 378/19, 378/99, 378/146, 378/62
• US Class Current: 378/62
• CPC Class Codes: A61B 6/032 Transmission computed tomography [CT]
• CPC Class Codes: A61B 6/4021 involving movement of the focal spot
• CPC Class Codes: A61B 6/4085 Cone-beams
• CPC Class Codes: A61B 6/4241 using energy resolving detectors, e.g. photon counting
• CPC Class Codes: A61B 6/482 involving multiple energy imaging
• CPC Class Codes: G01T 1/1644 using an array of optically separate scintillation elements permitting direct location of scintillations G01T1/1645 takes precedence
• CPC Class Codes: G01T 1/20181 Stacked detectors, e.g. for measuring energy and positional information using a combination of different types of scintillation detectors, e.g. phoswich detectors, G01T1/2008
• CPC Class Codes: G01T 1/20182 Modular detectors, e.g. tiled scintillators or tiled photodiodes stacked detectors G01T1/20181
• CPC Class Codes: G01T 1/202 the detector being a crystal

Abstract

A digital radiography system is disclosed having a multi-element curved detector assembly. The system includes an X-ray tube having a focal spot from which its X-ray energy primarily emanates, and which is spaced from the detector assembly to define a subject examination space. The detector assembly includes a number of individual detector elements each having a radiation sensitive face, the element faces collectively defining a concave curved surface oriented toward the focal spot. The assembly of elements can embody forms including a single curved line of elements, multiple similarly curved lines defining collectively a portion of a cylinder, or a three-dimensional curved array defining a portion of a sphere. Multiple layer stacked arrays can also be used. Each element responds to incident X-rays to produce an electrical charge signal indicative of the radiation. The detector assembly can be scanned relative to a subject in the examination space, and time delay and integrate circuitry is employed to improve the signal to noise characteristics of data represented by the electrical signals, by shifting and adding the signals in synchrony with scan motion prior to processing by imaging circuitry to derive a visual image of internal structure of a subject at the examination space.

Claims

1. A focused radiation detector comprising:

(a) a rear curved area detector layer, and

(b) a front curved area detector layer having a curvature similar to that of said rear detector layer and being superposed with respect to said rear layer.

2. A slit projection digital radiography system for imaging penetrating electromagnetic radiation, said system comprising:

(a) a radiation source including means for producing a thin spread beam of radiation generally defining a plane;

(b) a radiation detector forming at least one unclosed curved concave surface whose curvature defines a first axis, with said concave surface disposed toward the source and containing penetrative radiation-sensitive material, said detector comprising;

(i) a first detector layer for detecting radiation of predominantly a first energy range, and

(ii) a second detector layer positioned behind said first layer, relative to the source, for detecting radiation of a second energy range, and

(c) means for scanning said detector along a path defining an axis parallel to said plane and orthogonal to said first axis.

3. A slit scanning projection digital radiography imaging system comprising:

(a) a radiation source;

(b) a curved dual energy radiation detector disposed toward said source said curvature defining a first axis;

(c) mounting structure for maintaining a spacing between said source and detector,

(d) power means for actuating said source, and

(e) means for scanning said detector about an axis perpendicular to said first axis.

4. The system of claim 3, wherein:

(a) said source comprises an x-ray tube, and

(b) said detector comprises;

(i) a first x-ray sensitive layer for detecting x-ray energy of predominantly a first range, and

(ii) a second x-ray sensitive layer overlying said first layer for detecting x-ray energy of predominantly a second range.

5. The system of claim 3, wherein:

(a) said source defines a focal spot of radiation emanation, and

(b) said detector surface defines an arc having its center substantially coincident with said focal spot.

6. The system of claim 3, wherein said detector comprises:

a plurality of individual detector elements.

7. The system of claim 6, wherein:

(a) said detector elements are each responsive to incident radiation to produce an electrical signal indicating said radiation, and

(b) said system further comprises circuitry coupled to said detector elements and responsive to said electrical signals to produce a representation of a radiation pattern when incident on said elements.

8. A medical diagnostic slit scan projection digital radiography system comprising:

(a) an x-ray source including means for producing a thin fan beam of radiation for projection through a subject;

(b) a dual energy x-ray detector comprising a curved array of detector elements and additional detector elements superimposed over said array;

(c) structure for supporting said source and detector in a mutually facing relationship;

(d) means for rotationally moving said fan beam and detector relative to a subject to maintain alignment therebetween, said movement having a component in a direction orthogonal to the plane defined by the fan beam;

(e) power circuitry for actuating said source to propagate x-ray energy toward said detector, and

(f) imaging means coupled to said detector for producing a representation of x-ray energy projected on the detector.

9. The system of claim 8, wherein:

(a) said detector curved array defines substantially an arc, and

(b) said source comprises an x-ray tube having a focal spot substantially coincident with the center defined by said arc.

10. The system of claim 8, wherein said detector comprises:

a multi-layered multiple energy detector apparatus.

11. The system of claim 8, wherein:

(a) said detector defines a concave face disposed toward said source, said face defining a portion of a sphere, and

(b) said source comprises an x-ray tube having a focal spot substantially coincident with the center of said sphere.

12. A digital slit scan projection radiography system for imaging separate patterns of penetrative radiation falling respectively within first and second energy ranges, said system comprising:

(a) a penetrative radiation source defining a focal spot from which radiation primarily emanates for producing a fan beam of radiation defining a plane and rotating said beam about a first axis in said plane;

(b) a detector assembly comprising;

(i) a first array of detector elements mounted with each element having a receiving portion facing said source and said receiving portions of said first element array being each maintained at substantially a first predetermined distance from said focal spot, and

(ii) a second array of detector elements each having a radiation receiving portion, said radiation receiving portions of each of said second array of elements being maintained at a second predetermined distance from said focal spot, one of said first and second arrays being superposed over the other with respect to radiation when emanating from the focal spot;

(c) power means for actuating the source to propagate radiation from said focal spot toward said detector arrays,

(d) means for moving said detector along a curved path defining a second axis parallel to said first axis;

(e) circuitry coupled to said detector elements for producing by energy subtraction presentations of energy incident on said first and second arrays.

13. The system of claim 12, wherein:

each detector element of one of said detector arrays is aligned with a corresponding detector element of the other of said arrays along a line extending from said focal spot.

14. The system of claim 12, wherein each of said first and second arrays comprises a curvilinear array of detector elements.

15. A system for separately imaging shadowgraphic patterns of projected penetrative radiation falling within first and second energy ranges, said system comprising:

(a) a penetrative radiation source defining a focal region from which radiation is primarily emitted when the source is actuated;

(b) a first curved multi-element, multilinear portion containing a first penetrative radiation sensitive material disposed such that each point defined by the surface of said portion is located at substantially a same first predetermined distance from said focal region;

(c) a second curved multi-element, multilinear portion containing a second penetrative radiation sensitive material, each point defined by the surfaces of said second portion being located at substantially a same second predetermined distance from said focal region, said second distance differing from said first distance.

16. The system of claim 15, further comprising:

means for producing separate images by separately utilizing the radiation energy response of said first and second curved portions.

17. The system of claim 15, wherein:

one of said first and second portions being superposed over the other, such that radiation directed toward one of said layers is at least partially intercepted by the other.

18. The system of claim 15, wherein:

each of said curved portions defines a portion of a sphere.

19. The system of claim 15, wherein said radiation source comprises an x-ray tube the x-ray energy from which is emitted substantially from a neighborhood about a focal spot.

20. A medical diagnostic x-ray system comprising:

(a) a radiation source assembly for propagating penetrative radiation outwardly in a pattern definable by a solid angle;

(b) multi-element, multilinear area detector assembly having radiation sensitive material defining at least one face for receiving radiation from said source, said receiving face disposed to receive energy from said source substantially normally to said surface at substantially all locations of said detector face subtended by said solid angle and for producing analog electrical signals corresponding to received radiation, and

(c) means for producing an indication of a pattern of radiation energy incident upon said detector.

21. A medical diagnostic system comprising:

(a) a source of penetrative radiation;

(b) a detector unit comprising at least a 3×

3 array of individual detector elements each having a radiation receiving face, said elements being positioned so that the element receiving faces collectively define a substantially curved surface disposed toward the source, and said detector elements being arranged in a staggered pattern, and

(c) means coupled to said detector elements for producing a representation of a pattern of radiation from said source incident on detector unit.

22. In a radiation imaging system including a radiation source and imaging circuitry integratable with a detector for producing an image representing radiation incident on the detector, the improvement comprising:

a focused radiation detector comprising;

(a) a rear curved multi-element cellular area detector layer, and

(b) a front area detector layer superposed with respect to said rear layer to intercept radiation from the source prior to interception of source radiation by said rear detector layer.

23. In a slit scan projection energy subtraction digital x-ray imaging system including an x-ray source and imaging circuitry coupleable to a detector for producing an image of radiation incident on the detector, the improvement comprising:

a split energy x-ray detector apparatus comprising;

(a) a first detector structure comprising a first x-ray sensitive material arranged to define a first curved concave face, and

(b) a second detector structure comprising a second x-ray sensitive material arranged to define a second face overlying said first layer structure.

24. In a system for imaging penetrating electromagnetic radiation, including a radiation source, the improvement comprising:

a radiation detector curved to form a dome shaped concave surface disposed toward the source and containing penetration radiation-sensitive material.

25. A digital radiography system comprising:

(a) a multi-element multilinear curved detector assembly including a plurality of individual detector elements each having radiation sensitive material defining a face, said element faces collectively defining generally a concave curved surface;

(b) an x-ray tube having a focal spot from which said tube primarily propagates x-ray energy, said tube being sufficiently displaced from said detector assembly to define a subject examination space;

(c) power means for actuating a tube to propagate x-ray energy toward the detector assembly;

(d) imaging circuitry at least partially integral with said detector assembly, and

(e) display apparatus coupled to said imaging circuitry for producing an image of a subject located in said examination space.

26. A slit scan projection digital radiography x-ray imaging system comprising:

(a) an x-ray detector;

(b) an x-ray tube spaced from said detector to provide a subject examination space therebetween, said tube comprising an anode mounted for rotation about and axis and means for directing an electron beam incident upon said anode;

(c) power means for actuating said tube to propagate x-rays through said examination space toward said detector;

(d) apparatus for scanning said detector along a substantially arcuate path centered about a scanning axis, and

(e) apparatus for maintaining said tube with said anode rotational axis approximately perpendicular to said scanning axis.

27. The system of claim 26, wherein said tube maintaining apparatus maintains said tube positioned with said anode rotational axis tilted from said perpendicular by approximately eight degrees.

28. A system for imaging penetrative electromagnetic radiation, said system comprising:

(a) a radiation source;

(b) a radiation detector forming a domed shape and having a curved concave surface disposed toward the source and containing penetrative radiation sensitive material, and

(c) imaging circuitry coupled to said detector.

29. A system for imaging penetrative electromagnetic radiation, said system comprising:

(a) a radiation source;

(b) a radiation detector forming an unclosed curved concave surface disposed toward said source and including penetrative radiation sensitive material, said detector including a first detector portion comprising a multiplicity of individual detector elements including a first material for detecting radiation of predominantly a first energy range, and a second detector portion comprising a plurality of individual detector elements positioned behind said first material, relative to the source, of a second material for detecting radiation of a second energy range, said detector elements each producing an electrical signal in response to detection of radiation by said materials, and

(c) energy subtraction means coupled to said detector for providing an image of a shadowgraphic pattern of radiation projected incident upon said detector.

30. An x-ray imaging system comprising:

(a) an X-radiation source defining a focal spot;

(b) a detector assembly comprising sets of discrete radiation detectors, each set comprising a plurality of discrete detector elements, said detector element sets defining, in a plane extending through both detector sets, a cross section including at least two concentric arcs, said concentric arcs each having a center located substantially coincident with the focal spot of said x-ray source, and

(c) means, integral to said detector elements, for producing an image of a shadowgraphic pattern of x-radiation incident upon said detector assembly.

31. A medical diagnostic slit scan projection digital radiography system comprising:

(a) an x-ray source including means for producing a thin fan beam of radiation for projecting through a subject, said source comprising an x-ray tube having a focal spot;

(b) a curved multi-layered multiple energy detector apparatus comprising a curved array of detector elements and additional detector elements arranged behind said curved array with respect to said source;

(c) structure for supporting said source and detector in a substantially facing relationship;

(d) means for rotationally moving said fan beam and detector relative to a subject to maintain alignment therebetween, said movement having a component in a direction orthogonal to the plane defined by the fan beam;

(e) power circuitry for actuating said source to propagate x-ray energy toward said detector, and

(f) imaging means coupled to said detector for producing a representation of x-ray energy projected on the detector.

32. The system of claim 31, wherein:

said detector curved array defines substantially an arc having a center of curvature substantially coincident with said focal spot.

33. A digital slit scan projection radiography system for imaging separate patterns of penetrative radiation falling respectively within first and second energy ranges, said system comprising:

(a) a penetrative radiation source defining a focal spot from which radiation primarily emanates for producing a fan beam of radiation defining a plane and rotating said beam about a first axis in said plane;

(b) a detector assembly comprising;

(i) a first array of detector elements defining a dome shaped portion of a sphere and being mounted with each element having a receiving portion facing said source and said receiving portions of said first element array being each maintained at substantially a first predetermined distance from said focal spot, and

(ii) a second array of detector elements each having a radiation receiving portion, said second array defining a dome shaped portion of a sphere, said radiation receiving portions of each of said second array of elements being maintained at a second predetermined distance from said focal spot, one of said first and second arrays being superposed over the other with respect to radiation when emanating from said focal spot;

(c) power means for actuating the source to propagate radiation from said focal spot toward said detector arrays,

(d) means for moving said detector along a curved path defining a second axis parallel to said first axis;

(e) circuitry coupled to said detector elements for producing separate representations of energy incident on said first and second arrays.

34. A medical diagnostic slit scan projection energy subtraction digital radiography system comprising:

(a) an x-ray source including apparatus cooperative with said source for producing a thin fan beam of radiation for projection through a subject, said x-ray source defining a focal spot from which x-ray energy primarily emanates;

(b) a dual energy x-ray detector assembly comprising;

(i) a first curved array of x-ray detector elements defining a first radius of curvature and being focused substantially on said focal spot;

(ii) a second curved array of detector elements defining a second radius of curvature greater than said first radius of curvature, said second curved array also being substantially focused on said focal spot;

(c) structure for supporting said source and detector assembly;

(d) means for rotationally moving said fan beam and detector assembly relative to a subject to maintain alignment therebetween, said movement having a component in a direction orthogonal to the plane defined by the fan beam;

(e) power circuitry to actuating said source to propagate x-ray energy toward said detector, and

(f) imaging means coupled to said first and second curved detector element arrays for performing energy subtraction by the use of information produced by said detector arrays respectively, and for producing a visual representation of x-ray energy projected onto the detector assembly.

35. A medical diagnostic slit scan projection energy subtraction digital radiography system comprising:

(a) an x-ray source including apparatus cooperative with the source for producing a thin fan beam of radiation for projection through a subject;

(b) a dual energy x-ray detector comprising two stacked layers of detector elements one behind the other with respect to the source;

(c) structure for supporting said source and detector assembly in a mutually facing relationship;

(d) means for moving said fan beam and detector assembly relative to a subject to maintain alignment therebetween;

(e) power circuitry for actuating said source to said propagate x-ray energy toward said detector, and

(f) imaging means coupled to said respective detector array layers for performing energy subtraction on information derived from said respective detector layers and for producing a representation of x-ray energy projected on the detector.