US5400387A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Indirect measurement of voltage applied to diagnostic x-ray tubes
Assignee: General Electric Co
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Filing: 1994-03-01
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Granted: 1995-03-21
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Expires: 2014-03-01
Abstract
Abstract A CT system includes a pair of detectors in its detector array which measure x-ray intensity from a source after passing through a differential x-ray filter. The ratio of the signals produced by these two detector elements are input to a KV calculator which produces a signal indicative of x-ray tube voltage.
Inventors
- 👤 Michael F. Gard
- 👤 John M. Sandrik
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 18:12
CPC Classifications
G; G01; G01D; G01D7/00; G01D7/02; H; H05; H05G; H05G1/00; H05G1/08; H05G1/26; H05G1/265
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
136 words
An apparatus for measuring the voltage applied to an x-ray tube which comprises: a pair of x-ray detectors disposed in a beam of x-rays produced by the x-ray tube and being operable to produce respective signals I A and I B which indicate the intensity of detected x-rays; a differential filter (40) disposed in the x-ray beam to attenuate the x-ray intensity detected by one of said x-ray detectors (18) by an amount substantially greater than that detected by the other of said x-ray detectors (18); and voltage calculation means (41) connected to receive the detector signals I A and I B and calculate a tube voltage (KV) using the ratio (R) of the detector signals I A /I B and the following relationship: ##EQU4## where k 0 , k 1 and k 2 are constants.
Claim 2
Independent Claim
136 words
An apparatus for measuring the voltage applied to an x-ray tube which comprises: a pair of x-ray detectors disposed in a beam of x-rays produced by the x-ray tube and being operable to produce respective signals I A and I B which indicate the intensity of detected x-rays; a differential filter (40) disposed in the x-ray beam to attenuate the x-ray intensity detected by one of said x-ray detectors (18) by an amount substantially greater than that detected by the other of said x-ray detectors (18); and voltage calculation means (41) connected to receive the detector signals I A and I B and calculate a tube voltage (KV) using the ratio (R) of the detector signals I A /I B and the following relationship: ##EQU4## where k 0 , k 1 and k 2 are constants.
Claim 3
Dependent Claim
48 words
The apparatuses recited in claim 1 in which the pair of detectors form part of a detector array in an x-ray machine, and the voltage calculation means generates a signal indicative of the calculated tube voltage (KV) which is employed by the x-ray machine to produce an image.
Claim 4
Dependent Claim
28 words
The apparatus as recited in claim 2 in which the tube voltage signal is employed by the x-ray machine to make beam hardening corrections to x-ray scan data.
Claim 5
Dependent Claim
49 words
The apparatus as recited in claim 1 in which the coefficients k 0 , k 1 , and k 2 are calculated during a calibration process in which the ratio R is measured at a set of known x-ray tube voltages and a curve is fit to these measurements.
Claim 6
Dependent Claim
46 words
The apparatus as recited in claim 1 in which the differential filter is comprised of molybdenum having a first thickness in the beam of x-rays reaching one of said x-ray detectors and having a second thickness in the beam of x-rays reaching the other x-ray detector.
Claim 7
Dependent Claim
22 words
The apparatus as recited in claim 5 in which the first and second thicknesses differ by at least a factor of two.
Claim 8
Dependent Claim
20 words
The apparatus as recited in claim 1 in which the differential filter is mounted on the pair of x-ray detectors.
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) | 1998-03-20 | 1998-09-19 | 1999-03-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-03-20 | 2002-09-19 | 2003-03-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-03-20 | 2006-09-19 | 2007-03-21 | $7700.00 | Window Closed / Lapsed |