US4499159A
Expired / Lapsed
US
⏱️ 0.0 years remaining
X-ray image converters utilizing rare earth oxyhalide phosphors
Assignee: General Electric Co
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Filing: 1984-04-13
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Granted: 1985-02-12
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Expires: 2004-04-13
Abstract
Abstract Oxyhalides of lanthanum and gadolinium and coactivated with thulium ion and further containing an impurity ion and a second coactivator selected from praseodymium and neodymium, including mixtures thereof, exhibit reduced quantum noise when employed in X-ray image converter devices. In the preferred embodiments, small but effective amounts of ytterbium ion can also be incorporated into the phosphor material to reduce afterglow and a multilayer X-ray screen construction is disclosed employing the improved phosphors.
Inventors
- 👤 Marjorie J. Brines
- 👤 Jacob G. Rabatin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 02:00
CPC Classifications
G; G21; G21K; G21K4/00; C; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7766; C09K11/7767; C09K11/7769; C09K11/777; Y; Y10; Y10S; Y10S428/00; Y10S428/913; Y10S430/00; Y10S430/167; Y10S430/168
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
127 words
An improved X-ray image converter having phosphor crystals supported on a base member, said phosphor crystals having the general formula: M.sub.1-w-y-z OX:Tm.sub.w Yb.sub.y A.sub.z wherein M is one or more of La and Gd, X is one or more of Cl and Br, w is from about 0.0001 to about 0.01 mole per mole of phosphor, y is from zero to about 0.01 mole per mole of phosphor z is from about 0.0001 to about 0.01 mole per mole of phosphor, and A is one or more of Pr and Nd, said phosphor exhibiting relatively uniform ultraviolet emission scintillation intensities when excited by relatively equal energy X-ray photons from a radiation source in the 40-120 KVp range and a lower quatum noise than said phosphor absent A.
Claim 2
Dependent Claim
127 words
An improved X-ray image converter having phosphor crystals supported on a base member, said phosphor crystals having the general formula: M.sub.1-w-y-z OX:Tm.sub.w Yb.sub.y A.sub.z wherein M is one or more of La and Gd, X is one or more of Cl and Br, w is from about 0.0001 to about 0.01 mole per mole of phosphor, y is from zero to about 0.01 mole per mole of phosphor z is from about 0.0001 to about 0.01 mole per mole of phosphor, and A is one or more of Pr and Nd, said phosphor exhibiting relatively uniform ultraviolet emission scintillation intensities when excited by relatively equal energy X-ray photons from a radiation source in the 40-120 KVp range and a lower quatum noise than said phosphor absent A.
Claim 3
Dependent Claim
15 words
An improved X-ray image converter as in claim 1 wherein the phosphor is lanthanum oxyhalide.
Claim 4
Dependent Claim
15 words
An improved X-ray image converter as in claim 2 wherein the phosphor is lanthanum oxybromide.
Claim 5
Dependent Claim
24 words
An improved X-ray image converter as in claim 1 which further includes photographic film means to record the light image produced by said phosphor.
Claim 6
Dependent Claim
13 words
An improved X-ray image converter as in claim 1 comprising an X-ray screen.
Claim 7
Dependent Claim
25 words
An improved X-ray screen as in claim 5 wherein said photographic film further includes an ultraviolet absorbing dye to help reduce crossover through said support.
Claim 8
Dependent Claim
24 words
An improved X-ray screen as in claim 5 which further includes light reflecting layers positioned adjacent the exteriormost major surfaces of the phosphor layers.
Claim 9
Dependent Claim
176 words
An improved multi-layer X-ray screen construction which comprises: (a) a photographic film having emulsion layers disposed on each major surface and separated by an optically transparent support, (b) a pair of phosphor layers being positioned on each side of said photographic film to form a sandwich construction, and (c) each of said phosphor layers comprising phosphor crystals supported on a base member, said phosphor crystals having the general formula: M.sub.1-w-y-z OX:Tm.sub.w Yb.sub.y A.sub.z wherein M is one or more of La and Gd, X is one or more of Cl and Br W is from about 0.0001 to about 0.01 mole per mole of phosphor, Y is from zero to about 0.01 mole per mole of phosphor Z is from about 0.0001 to about 0.01 mole per mole of phosphor, and A is one or more of Pr and Nd, said phosphor exhibiting relatively uniform ultraviolet emission scintillation intensities when excited by relatively equal energy X-ray photons from a radiation source in the 40-120 KVp range and a lower quantum noise, than said phosphor absent A.
Claim 10
Dependent Claim
176 words
An improved multi-layer X-ray screen construction which comprises: (a) a photographic film having emulsion layers disposed on each major surface and separated by an optically transparent support, (b) a pair of phosphor layers being positioned on each side of said photographic film to form a sandwich construction, and (c) each of said phosphor layers comprising phosphor crystals supported on a base member, said phosphor crystals having the general formula: M.sub.1-w-y-z OX:Tm.sub.w Yb.sub.y A.sub.z wherein M is one or more of La and Gd, X is one or more of Cl and Br W is from about 0.0001 to about 0.01 mole per mole of phosphor, Y is from zero to about 0.01 mole per mole of phosphor Z is from about 0.0001 to about 0.01 mole per mole of phosphor, and A is one or more of Pr and Nd, said phosphor exhibiting relatively uniform ultraviolet emission scintillation intensities when excited by relatively equal energy X-ray photons from a radiation source in the 40-120 KVp range and a lower quantum noise, than said phosphor absent A.
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) | 1988-02-12 | 1988-08-13 | 1989-02-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-02-12 | 1992-08-13 | 1993-02-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-02-12 | 1996-08-13 | 1997-02-12 | $7700.00 | Window Closed / Lapsed |