US5335260A
Expired / Lapsed
US
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Calibration phantom and improved method of quantifying calcium and bone density using same
Assignee: Individual
•
Filing: 1992-11-25
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Granted: 1994-08-02
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Expires: 2012-11-25
Abstract
Abstract A calibration phantom representative of human tissue containing variable concentrations of calcium serves as a calibration reference for quantifying calcium, bone mass and bone mineral density in radiography and CT imaging systems. The method of fabrication of the calibration phantom provides the long-term stable incorporation of calcium into a tissue equivalent material which allows accurate, standardized, and reproducible quantification of calcium and bone mineral density in radiography and CT imaging systems. A method of using the calibration phantom for quantifying calcium and bone includes placement of part of a patient's anatomy in a bolusing apparatus to provide uniform attenuation of the x-ray beam passing through and around the patient's anatomy. A x-ray filter plate may be used to predictably attenuate the x-ray beam.
Inventors
- 👤 Ben A. Arnold
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 06:57
CPC Classifications
A; A61; A61B; A61B6/00; A61B6/50; A61B6/505; A61B6/58; A61B6/582; A61B6/583; A61B6/48; A61B6/482
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
179 words
A method of quantifying calcium and bone density in the body of a patient using a calibration reference phantom comprising stable, substantially human tissue equivalent material with respect to x-ray attenuation and absorption properties and calcium homogeneously blended therein, and an x-ray imaging system, comprising: positioning the calibration phantom proximal to a part of the patient's anatomy such that x-rays pass through the patient and the phantom simultaneously; placing said phantom and said portion of the patient's anatomy within an apparatus comprising a container having substantially human tissue equivalent materials with respect to x-ray attenuation and absorption characteristics in a bolusing structure of a fixed size and shape, such that the x-ray beam which passes through the patient and phantom is similarly attenuated and has a constant path length; placing an x-ray filter plate between said apparatus and said x-ray beam to predictably attenuate the x-ray beam; creating an image of the phantom and the portion of the patient's anatomy; and comparing the image of the phantom and the patient's anatomy to determine calcium content in the patient's anatomy.
Claim 2
Independent Claim
179 words
A method of quantifying calcium and bone density in the body of a patient using a calibration reference phantom comprising stable, substantially human tissue equivalent material with respect to x-ray attenuation and absorption properties and calcium homogeneously blended therein, and an x-ray imaging system, comprising: positioning the calibration phantom proximal to a part of the patient's anatomy such that x-rays pass through the patient and the phantom simultaneously; placing said phantom and said portion of the patient's anatomy within an apparatus comprising a container having substantially human tissue equivalent materials with respect to x-ray attenuation and absorption characteristics in a bolusing structure of a fixed size and shape, such that the x-ray beam which passes through the patient and phantom is similarly attenuated and has a constant path length; placing an x-ray filter plate between said apparatus and said x-ray beam to predictably attenuate the x-ray beam; creating an image of the phantom and the portion of the patient's anatomy; and comparing the image of the phantom and the patient's anatomy to determine calcium content in the patient's anatomy.
Claim 3
Dependent Claim
11 words
The method of claim 1, wherein said calcium is calcium phosphate.
Claim 4
Dependent Claim
11 words
The method of claim 1, wherein said calcium is calcium hydroxyapatite.
Claim 5
Dependent Claim
23 words
The method of claim 1, wherein said tissue equivalent material comprises a mixture of low density polyethylene, calcium carbonate, and heavy magnesium oxide.
Claim 6
Dependent Claim
21 words
The method of claim 1 wherein said imaging system is a projection x-ray system and said calcium content is bone mass.
Claim 7
Dependent Claim
21 words
The method of claim 1 wherein said imaging system is a computed tomography system and said calcium content is bone density.
Claim 8
Dependent Claim
12 words
The method of claim 1, wherein said filter plate comprises a metal.
Claim 9
Independent Claim
106 words
A method of quantifying bone density in a patient using a conventional dental x-ray system and a calibration reference phantom comprising stable, substantially tissue equivalent material with respect to x-ray attenuation properties and calcium homogeneously blended therein, comprising: positioning the calibration reference phantom inside the patient's mouth such that x-rays pass through the patient and the phantom simultaneously, said calibration reference phantom being formed into varying effective thicknesses to simulate varying bone density; creating an image of the phantom and the patient's bone using a single x-ray exposure; and comparing the image of the phantom and the patient's bone to determine bone density in the patient.
Claim 10
Independent Claim
106 words
A method of quantifying bone density in a patient using a conventional dental x-ray system and a calibration reference phantom comprising stable, substantially tissue equivalent material with respect to x-ray attenuation properties and calcium homogeneously blended therein, comprising: positioning the calibration reference phantom inside the patient's mouth such that x-rays pass through the patient and the phantom simultaneously, said calibration reference phantom being formed into varying effective thicknesses to simulate varying bone density; creating an image of the phantom and the patient's bone using a single x-ray exposure; and comparing the image of the phantom and the patient's bone to determine bone density in the patient.
Claim 11
Dependent Claim
11 words
The method of claim 8, wherein said calcium is calcium phosphate.
Claim 12
Dependent Claim
12 words
The method of claim 8, wherein said calcium is a calcium hydroxyapatite.
Claim 13
Independent Claim
120 words
A method of quantifying bone density in a patient using a conventional dental x-ray system and a calibration reference phantom comprising stable, substantially tissue equivalent material with respect to x-ray attenuation properties and calcium homogeneously blended therein, comprising: positioning the calibration reference phantom inside the patient's mouth such that x-rays pass through the patient and the phantom simultaneously, said calibration reference phantom being formed into varying effective thicknesses to simulate varying bone density; creating an image of the phantom and the patient's bone using a single x-ray exposure; and comparing the image of the phantom and the patient'bone to determine bone density in the patient, wherein said tissue equivalent material comprises a mixture of polyethylene, calcium carbonate, and magnesium oxide.
Claim 14
Independent Claim
120 words
A method of quantifying bone density in a patient using a conventional dental x-ray system and a calibration reference phantom comprising stable, substantially tissue equivalent material with respect to x-ray attenuation properties and calcium homogeneously blended therein, comprising: positioning the calibration reference phantom inside the patient's mouth such that x-rays pass through the patient and the phantom simultaneously, said calibration reference phantom being formed into varying effective thicknesses to simulate varying bone density; creating an image of the phantom and the patient's bone using a single x-ray exposure; and comparing the image of the phantom and the patient'bone to determine bone density in the patient, wherein said tissue equivalent material comprises a mixture of polyethylene, calcium carbonate, and magnesium oxide.
Claim 15
Independent Claim
114 words
A method of quantifying bone density in a living subject using a projection x-ray imaging system and a calibration reference phantom, comprising: placing a phantom adjacent to a portion of the subject, said phantom having varying effective thicknesses of substantially tissue equivalent material with respect to x-ray attenuation properties, said substantially tissue equivalent material having calcium blended homogeneously therein so that said varying effective thicknesses of said phantom provide multiple calibrations; creating an image of the phantom and the portion of the subject simultaneously using a single x-ray exposure and an imaging detector; and comparing the images of the phantom and the portion of the subject to quantitatively determine bone density in the subject.
Claim 16
Independent Claim
114 words
A method of quantifying bone density in a living subject using a projection x-ray imaging system and a calibration reference phantom, comprising: placing a phantom adjacent to a portion of the subject, said phantom having varying effective thicknesses of substantially tissue equivalent material with respect to x-ray attenuation properties, said substantially tissue equivalent material having calcium blended homogeneously therein so that said varying effective thicknesses of said phantom provide multiple calibrations; creating an image of the phantom and the portion of the subject simultaneously using a single x-ray exposure and an imaging detector; and comparing the images of the phantom and the portion of the subject to quantitatively determine bone density in the subject.
Claim 17
Dependent Claim
12 words
The method of claim 12, wherein said phantom is a stepwedge phantom.
Claim 18
Dependent Claim
12 words
The method of claim 12, wherein said imaging detector is x-ray film.
Claim 19
Dependent Claim
13 words
The method of claim 12, wherein said comparing is performed using a computer.
Claim 20
Dependent Claim
45 words
A calibration reference phantom for use in quantifying bone density using a projection x-ray imaging system comprising: a stable, substantially tissue equivalent material with respect to x-ray attenuation properties and calcium blended homogeneously therein, said material formed into varying effective thicknesses to provide multiple calibrations.
Claim 21
Dependent Claim
45 words
A calibration reference phantom for use in quantifying bone density using a projection x-ray imaging system comprising: a stable, substantially tissue equivalent material with respect to x-ray attenuation properties and calcium blended homogeneously therein, said material formed into varying effective thicknesses to provide multiple calibrations.
Claim 22
Dependent Claim
13 words
The calibration reference phantom of claim 16, wherein said calcium is calcium hydroxyapatite.
Claim 23
Dependent Claim
22 words
The calibration reference phantom of claim 16, wherein said tissue equivalent material comprises a mixture of polyethylene, calcium carbonate, and magnesium oxide.
Claim 24
Dependent Claim
15 words
The calibration reference phantom of claim 16, wherein said phantom has a step wedge shape.
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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) | 1997-08-01 | 1998-01-31 | 1998-08-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-08-01 | 2002-01-31 | 2002-08-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-08-01 | 2006-01-31 | 2006-08-02 | $7700.00 | Window Closed / Lapsed |