US4398092A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Shaped detector
Assignee: Technicare Corp
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Filing: 1981-05-20
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Granted: 1983-08-09
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Expires: 2001-05-20
Abstract
Abstract A radiation detector or detector array which has a non-constant spatial response individually and in combination with a tomographic scanner. The detector has a first dimension which is oriented parallel to the plane of the scan circle in the scanner. Along the first dimension, the detector is most responsive to radiation received along a centered segment of the dimension and less responsive to radiation received along edge segments. This non-constant spatial response can be achieved in a detector comprised of a scintillation crystal and a photoelectric transducer. The scintillation crystal in one embodiment is composed of three crystals arranged in layers, with the center crystal having the greatest light conversion efficiency. In a preferred embodiment, the non-constant spatial response is achieved in a detector comprised of a single scintillation crystal whose response is shaped by inducing along said first dimension a scintillation conversion efficiency gradient. In the single crystal embodiment, the gradient is chosen so that the crystal has greater conversion efficiency centrally than peripherally.
Inventors
- 👤 Roland W. Carlson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 05:17
CPC Classifications
G; G01; G01T; G01T1/00; G01T1/16; G01T1/20; G01T1/202; A; A61; A61B; A61B6/00; A61B6/02; A61B6/03; A61B6/032; G01T1/161; G01T1/164; G01T1/1641; G01T1/1644
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
160 words
A computerized tomographic scanning apparatus for examining with radiation a planar slice of an object in the plane of a scan circle and producing a representation of an image of the planar slice, comprising: at least one source of radiation for producing at least a beam of radiation in the plane of said scan circle; radiation detector means having at least one radiation detector for producing electrical signals in response to received radiation, said detector means disposed to receive from the source radiation which has traversed the scan circle, said radiation detector including a scintillation crystal for converting variations in incident radiation intensity into variations in light intensity, said scintillation crystal having a spatially variant radiation conversion efficiency such that said radiation detector has a non-constant spatial response in at least a first dimension in the plane of the scan circle; and processing means for processing the electrical signals from the detector means to produce the representation of an image.
Claim 2
Dependent Claim
160 words
A computerized tomographic scanning apparatus for examining with radiation a planar slice of an object in the plane of a scan circle and producing a representation of an image of the planar slice, comprising: at least one source of radiation for producing at least a beam of radiation in the plane of said scan circle; radiation detector means having at least one radiation detector for producing electrical signals in response to received radiation, said detector means disposed to receive from the source radiation which has traversed the scan circle, said radiation detector including a scintillation crystal for converting variations in incident radiation intensity into variations in light intensity, said scintillation crystal having a spatially variant radiation conversion efficiency such that said radiation detector has a non-constant spatial response in at least a first dimension in the plane of the scan circle; and processing means for processing the electrical signals from the detector means to produce the representation of an image.
Claim 3
Dependent Claim
18 words
A computerized tomographic scanning apparatus according to claim 1 wherein said scintillation crystal is doped with an activator.
Claim 4
Dependent Claim
42 words
A computerized tomographic apparatus according to claim 2 wherein the density of said activator in said scintillation crystal is distributed therein such that the detector is more responsive to radiation toward the center of said first dimension then toward either edge thereof.
Claim 5
Dependent Claim
21 words
A computerized apparatus according to claim 1 wherein the response of said detector is characterized by a generally bell shaped function.
Claim 6
Dependent Claim
15 words
A computerized tomographic apparatus according to claim 2 wherein the scintillation crystal is sodium iodide.
Claim 7
Dependent Claim
14 words
A computerized apparatus according to claim 2 wherein the scintillation crystal is cesium iodide.
Claim 8
Dependent Claim
17 words
A computerized tomographic apparatus according to either of claims 5 or 6 wherein the activator is thallium.
Claim 9
Dependent Claim
38 words
A computerized tomographic apparatus according to claim 1 wherein said scintillation crystal has a relatively high scintillation conversion efficiency such as cadmium tungstate, wherein said crystal has an impurity distributed therein in a gradient along said first dimension.
Claim 10
Dependent Claim
72 words
An apparatus according to claim 1 wherein said scintillation crystal is more responsive to radiation received along a first centrally disposed portion of the crystal than to radiation received along at least a second peripherally disposed portion of the crystal, said second portion disposed adjacent the first portion along the first dimension, whereby the crystal weights radiation received adjacent the center of the detector more heavily than radiation received adjacent the edges.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-08-08 | 1987-02-07 | 1987-08-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-08-08 | 1991-02-07 | 1991-08-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-08-08 | 1995-02-07 | 1995-08-09 | $7700.00 | Window Closed / Lapsed |