EP0212836A1
Expired / Lapsed
EP
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Radiation imaging systems
Assignee: Philips Nuclear Medicine Inc
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Filing: 1986-07-14
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Granted: —
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Expires: 2006-07-14
Abstract
Abstract A radiation imaging apparatus and method e.g. for computed tomography x-ray.imaging employing a radiation detector which enhances the detector output due to lower energy components of the incident radiation. One embodiment includes first and second layers (190, 192) of crystalline scintillation material mutually aligned in a path of x-rays to be detected, to receive the x-rays in sequence. The layer (190) upstream in the x-ray path comprises a scintillation material having a relatively high efficiency for converting x-ray energy to light. The downstream layer (192) comprises a scintillation material having a relatively lower efficiency for x-ray/light conversion. A photodiode (198) is positioned to view both scintillation layers (190, 192) simultaneously and to respond to scintillations in either or both. Scintillation crystal material surfaces can be coated with reflective material (194) to enhance the effects of their scintillations. The photodiode (198) thus combines x-ray indicating scintillations from both crystals while in analog form. Another embodiment comprises a photodiode and an optically coupled scintillation crystal, with the photodiode upstream in the x-ray beam path relative to the crystal (Fig. 4).
Inventors
- 👤 Carl J. Brunnett
- 👤 Rodney A. Mattson
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 17:27
CPC Classifications
G; G01; G01T; G01T1/00; G01T1/16; G01T1/20; G01T1/202; G01T1/2018; G01T1/20183
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
74 words
A radiation imaging system comprising: a radiation source for propagating radiation along a path; a detector assembly (19) in said radiation path for producing an analog output signal in response to said radiation; and imaging circuitry (14, 16, 17) responsive to said output signal characterised in that said detector assembly (19) is arranged so as to enhance a component of said output signal produced in response to a lower energy component of said radiation.
Claim 2
Dependent Claim
74 words
A radiation imaging system comprising: a radiation source for propagating radiation along a path; a detector assembly (19) in said radiation path for producing an analog output signal in response to said radiation; and imaging circuitry (14, 16, 17) responsive to said output signal characterised in that said detector assembly (19) is arranged so as to enhance a component of said output signal produced in response to a lower energy component of said radiation.
Claim 3
Independent Claim
76 words
A system according to Claim-1 wherein said detector assembly comprises first and second components (102, 104 or 110 or 120, 122 or 190, 192) preferentially responsive to lower and higher energy components of said radiation respectively and a third component (106 or 112 or 124 or 198) for producing said output signal in response to the responses of said first and second components (102, 104 or 110 or 120,- 122 or 190, 192) to said radiation.
Claim 4
Dependent Claim
47 words
A system according to Claim 2 wherein said first and second detector assembly components (102, 104 or 110 or 120, 122 or 190, 192) comprise scintillation material and said third component (106 or 112 or 124 or 198) comprises a detector for scintillation produced by said material.
Claim 5
Dependent Claim
61 words
A system according to Claim 3 wherein said first and second detector assembly components (102, 104 or 120, 122 or 190, 192) are arranged serially along said radiation path with said first detector assembly component (102, 120 or 190) nearer said source and having a higher photon to light conversion efficiency than said second detector assembly component (104, 122 or 192).
Claim 6
Dependent Claim
33 words
A system according to Claim 4 wherein said third component (106 or 198) is disposed on said radiation path on the side of said second component (104 or 192) remote from said source.
Claim 7
Dependent Claim
25 words
A system according to Claim 4 wherein said third component (124) is disposed along said radiation path between said first component (120) and said source.
Claim 8
Dependent Claim
40 words
A system according to Claim 6 wherein said detector assembly includes a further component (121) between said first and second components (120, 122) to reduce the response of said third component (124) to scintillation produced in said second component (122).
Claim 9
Independent Claim
22 words
A system according to any one of Claims 4 to 7 wherein said first component (102, 120 or 190) comprises cesium iodide.
Claim 10
Independent Claim
22 words
A system according to any one of Claims 4 to 8 wherein said second component (104, 122 or 192) comprises cadmium tungstate.
Claim 11
Independent Claim
32 words
A system according to any one of Claims 4 to 7 wherein said first (102, 120 or 190) and second (104, 122 or 192) components comprise cadmium tungstate and bismuth germanate respectively.
Claim 12
Independent Claim
49 words
A system according to any one of Claims 4 to 10 wherein said first (102, 120 or 190) and second (104, 122 or 192) components are in the form of layers of scintillation material having thicknesses in the range 0.1 to 0.4 mm and of substantially 2.0 mms respectively.
Claim 13
Dependent Claim
49 words
A system according to Claim 3 wherein said first and second components comprise regions of a single layer of scintillation material (110) respectively nearer and further from said source and said third component (112) is disposed along said radiation path between said source and said first and second components.
Claim 14
Dependent Claim
23 words
A system according to Claim 12 wherein said scintillation material comprises a material which is semitransparent to the scintillations produced by said material.
Claim 15
Dependent Claim
13 words
A system according to Claim 13 wherein said scintillation material comprises cadmium tungstate.
Claim 16
Independent Claim
23 words
A system according to any one of Claims 3 to 14 wherein said third component (106, 112, 124 or 198) is a photodiode.
Claim 17
Independent Claim
24 words
A system according to any one of Claims 3 to 15 wherein said first and second detector assembly components (190, 192) have different geometries.
Claim 18
Independent Claim
38 words
A system according to any one of Claims 3 to 16 wherein at least one of said first and second detector assembly components (190, 192) includes a surface layer (194) of reflective material to assist in said enhancement.
Claim 19
Dependent Claim
18 words
A system according to Claim 2 wherein said first and second detector assembly components comprise semi-solid state materials.
Claim 20
Dependent Claim
19 words
A system according to Claim 18 wherein said first component comprises silicon and said second component comprises mercuric iodide.
Claim 21
Independent Claim
42 words
A system according to any one of Claims 2 to 19 wherein said first (102, 110, 120 or 190) second (104, 110, 122 or 192) and third (104, 112, 124 or 198) detector assembly components are arranged in stacked closely spaced configuration.
Claim 22
Dependent Claim
46 words
A system according to Claim '1 or Claim 2 wherein said detector assembly comprises an ionization detector having two sets of charge collection plates arranged sequentially in the radiation path, the outputs appearing at the two sets of plates being combined to form said output signal.
Claim 23
Dependent Claim
22 words
A system according to Claim 21 wherein the outputs of the two sets of plates are subject to differential amplification before combination.
Claim 24
Dependent Claim
29 words
A system according to Claim 21 or Claim 22 wherein the plates of the set of plates nearer said source are larger than the plates of the other set.
Claim 25
Independent Claim
20 words
A system according to any one of the preceding claims wherein the system is a computed tomography x-ray image system.
Claim 26
Dependent Claim
22 words
A radiation detector assembly suitable for use as the detector assembly in a system according to any one of the preceding claims.
Claim 27
Dependent Claim
116 words
A radiation imaging method characterised by the steps of: producing a beam of polyenergetic penetrative radiation: producing a first analog representation preferentially in response to lower energy components of said radiation; producing a second representation preferentially in response to higher energy components of said mixed energy radiation beam; enhancing said first lower energy representation with respect to said second higher energy representation, and producing a single output representation which is a function of both said first enhanced lower energy representation and said second higher energy representation by combining in analog form said first and said second representations; and producing, in response to said single output, a representation of a portion of an image of said radiation.
Claim 28
Dependent Claim
116 words
A radiation imaging method characterised by the steps of: producing a beam of polyenergetic penetrative radiation: producing a first analog representation preferentially in response to lower energy components of said radiation; producing a second representation preferentially in response to higher energy components of said mixed energy radiation beam; enhancing said first lower energy representation with respect to said second higher energy representation, and producing a single output representation which is a function of both said first enhanced lower energy representation and said second higher energy representation by combining in analog form said first and said second representations; and producing, in response to said single output, a representation of a portion of an image of said radiation.
References Cited (Backward Citations)
WO1981000457A1
Cited
US4511799A
Cited
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