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US4868392A
Expired / Lapsed
US
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Method of and apparatus for modulating the counts of a PET camera
Assignee: Individual
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Filing: 1988-05-05
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Granted: 1989-09-19
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Expires: 2008-05-05
Abstract
Abstract A PET camera is provided with a modulator of a material having an atomic number of at least 82. The modulator allows uses doses much higher than the PET system can handle by throttling through just the maximum allowable counting rate. As the counting activity delays, the amount of modulation is reduced so that the camera is kept counting near its maximum limit for the scanning period.
Inventors
- 👤 Wai-Hoi Wong
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 19:53
CPC Classifications
G; G01; G01T; G01T1/00; G01T1/29; G01T1/2914; G01T1/2985; A; A61; A61B; A61B6/00; A61B6/02; A61B6/03; A61B6/037
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
112 words
The method of operating a positron emission tomography camera for measuring concentrations of positron emitting radioisotopes which measure radiation from a patient including true counts and accidental counts comprising, providing a changeable modulator of a material having an atomic number of at least 82, around a patient for use as a gamma ray modulator for allowing only the maximum allowable counting rate through the modulator, injecting an amount of radiation into the patient normally sufficient to initially saturate the maximum camera transfer capability, as the counting activity of the camera decays, reducing the amount of modulation to keep the counting rate of the camera near its maximum limit for the scanning period.
Claim 2
Independent Claim
112 words
The method of operating a positron emission tomography camera for measuring concentrations of positron emitting radioisotopes which measure radiation from a patient including true counts and accidental counts comprising, providing a changeable modulator of a material having an atomic number of at least 82, around a patient for use as a gamma ray modulator for allowing only the maximum allowable counting rate through the modulator, injecting an amount of radiation into the patient normally sufficient to initially saturate the maximum camera transfer capability, as the counting activity of the camera decays, reducing the amount of modulation to keep the counting rate of the camera near its maximum limit for the scanning period.
Claim 3
Dependent Claim
24 words
The method of claim 1 wherein the modulation is performed by a plurality of rings and is reduced by removing one or more rings.
Claim 4
Dependent Claim
71 words
In a positron emission tomography camera having a plurality of detector rings positioned side-by-side around a patient area to detect radiation from the patient, the improvement comprising, a changeable modulator positioned between the detector rings and the patient area for use as a gamma ray modulator for allowing only the maximum allowable counting rate through the modulator, said modulator being of a material having an atomic number of at least 82.
Claim 5
Dependent Claim
71 words
In a positron emission tomography camera having a plurality of detector rings positioned side-by-side around a patient area to detect radiation from the patient, the improvement comprising, a changeable modulator positioned between the detector rings and the patient area for use as a gamma ray modulator for allowing only the maximum allowable counting rate through the modulator, said modulator being of a material having an atomic number of at least 82.
Claim 6
Dependent Claim
14 words
The apparatus of claim 3 wherein the modulator includes, a plurality of concentric rings.
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) | 1992-09-18 | 1993-03-20 | 1993-09-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-09-18 | 1997-03-20 | 1997-09-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-09-18 | 2001-03-20 | 2001-09-19 | $7700.00 | Window Closed / Lapsed |