US4983841A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Non-invasive inspection
Assignee: Rolls Royce PLC
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Filing: 1989-09-26
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Granted: 1991-01-08
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Expires: 2009-09-26
Abstract
Abstract Residual core material can be detected inside hollow cast articles using positron emission tomography. Positron radio-isotope material is inducted into any residual core material present by immersing a cast article in an aqueous solution of radio-isotope emitter, for example gallium. Absorbed gallium subsequently emits positrons which are annihilated in collisions with electrons emitting two 511 KeV gamma rays in diametrically opposite directions. The emissions are detected and tracked by a PET camera and the resulting images correlated with a sectioned image of the article as a check on the location of detected core material. Initially a low-dose-rate solution for the purpose of merely establishing the presence of core material is used but a second optional process step introduces a more active solution allowing a PET camera to collect sufficient data to image absorbed isotope.
Inventors
- 👤 Peter A. E. Stewart
- 👤 Richard T. Skelton
- 👤 Martin J. Allen
- 👤 Joseph Douglas
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 05:38
CPC Classifications
G; G01; G01N; G01N23/00; G01N23/02; G01N23/04; G01N23/046; G01T; G01T1/00; G01T1/29; G01T1/2914; G01T1/2985; G01N2223/00; G01N2223/40; G01N2223/419
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
73 words
A method of non-invasively inspecting a hollow article for trapped foreign matter comprising: filling the interior of the hollow article with a mixture comprising a carrier fluid and a radioisotope capable of being absorbed by said trapped foreign matter; draining the mixture comprising unabsorbed radioisotope from the interior of the article; and using radiation sensitive detecting means to track emissions from the radioisotope absorbed by any trapped foreign matter within the hollow article.
Claim 2
Independent Claim
73 words
A method of non-invasively inspecting a hollow article for trapped foreign matter comprising: filling the interior of the hollow article with a mixture comprising a carrier fluid and a radioisotope capable of being absorbed by said trapped foreign matter; draining the mixture comprising unabsorbed radioisotope from the interior of the article; and using radiation sensitive detecting means to track emissions from the radioisotope absorbed by any trapped foreign matter within the hollow article.
Claim 3
Dependent Claim
35 words
A method according to claim 1, wherein the radio isotope emits positrons and the radiation sensitive detecting means is responsive to gamma-photons emitted upon annihilation of at least one of said positrons with an electron.
Claim 4
Dependent Claim
21 words
A method according to claim 2, wherein the gamma-photon emissions are tracked to source using a multi-element radiation sensitive detecting means.
Claim 5
Dependent Claim
19 words
A method according to claim 3, wherein the multi-element radiation sensitive detecting means is a positron emission tomography system.
Claim 6
Dependent Claim
24 words
A method according to claim 4, wherein the positron emission tomography system is employed to produce an image of the sources of tracked emissions.
Claim 7
Dependent Claim
23 words
A method according to claim 5, wherein an image of the hollow article undergoing inspection is superimposed on the image of emission sources.
Claim 8
Dependent Claim
18 words
A method according to claim 6, wherein said superimposed image comprises a sectional view of the hollow article.
Claim 9
Dependent Claim
25 words
A method according to claim 1, wherein the detecting means comprises a single counter for monitoring the total radiation level from the inspected hollow article.
Claim 10
Dependent Claim
29 words
A method according to claim 8, wherein the hollow article is judged to contain trapped foreign matter if a count rate of the detecting means exceeds a predetermined level.
Claim 11
Dependent Claim
64 words
A method according to claim 7, wherein an article judged to contain trapped foreign matter is recycled through said steps of: tracking to source the gamma-photon emissions; producing an image of the sources of tracked emissions; and superimposing an image comprising a sectional view of the object undergoing inspection on the image of emission sources, to identify the location of the trapped foreign matter.
Claim 12
Dependent Claim
14 words
A method according to claim 4, wherein the carrier fluid is an aqueous solution.
Claim 13
Dependent Claim
21 words
A method according to claim 1 further comprising a step of leaching out initial core material prior to filling the interior.
Claim 14
Dependent Claim
25 words
A method according to claim 1, wherein the step of filling the interior of the hollow article comprises immersing the hollow article in the mixture.
Claim 15
Dependent Claim
11 words
A method according to claim 1, wherein the radioisotope comprises gallium.
Claim 16
Dependent Claim
13 words
A method according to claim 14, wherein the gallium is radioactive gallium 68.
Claim 17
Dependent Claim
13 words
A method according to claim 14, wherein the mixture further comprises gallium III.
Claim 18
Dependent Claim
34 words
A method according to claim 1, wherein when the hollow article is judged to contain trapped foreign matter, the steps of filling, draining and detecting are repeated with an increased concentration of the radioisotope.
Claim 19
Dependent Claim
26 words
A method according to claim 10, wherein the radioisotope is introduced into the hollow article in the mixture comprising an aqueous solution, gallium and gallium III.
Claim 20
Dependent Claim
17 words
A method according to claim 18 further comprising a first step of leaching out initial core material.
Claim 21
Dependent Claim
25 words
A method according to claim 18, wherein the step of filling the interior of the hollow article comprises immersing the hollow article in the mixture.
Claim 22
Dependent Claim
36 words
A method according to claim 1, wherein when the hollow article is judged to contain trapped foreign matter, the steps of filling, draining and detecting are repeated with a second radioactive isotope different from said radioisotope.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-01-07 | 1994-07-09 | 1995-01-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-01-07 | 1998-07-09 | 1999-01-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-01-07 | 2002-07-09 | 2003-01-08 | $7700.00 | Window Closed / Lapsed |