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US5204888A
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Bone mineral content measuring apparatus
Assignee: Hitachi Ltd
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Filing: 1990-12-14
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Granted: 1993-04-20
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Expires: 2010-12-14
Abstract
Abstract A bone mineral content measuring apparatus for obtaining the bone mineral content of an object to be examined by irradiating X-rays onto the object and measuring the X-rays which have passed through the object. An X-ray generating device generates X-rays having a continuous spectrum. The X-rays generated pass through an X-ray filter before the irradiation of the object or after the transmission of the object. The X-ray filter is composed of a substance having an X-ray absorbing characteristic with the K-absorption edge at a predetermined energy value. The X-rays which have passed through the X-ray filter and the object are detected by the X-ray detector. A data analyzer inputs the detected X-ray detection data and analyzes the bone mineral content of the object on the basis of the X-ray absorbing characteristic of the X-ray filter.
Inventors
- 👤 Toshiaki Tamegai
- 👤 Kazuyuki Tamura
- 👤 Shigeo Kimura
- 👤 Koichi Kawamura
- 👤 Shizuo Ninomiya
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 22:59
CPC Classifications
G; G01; G01N; G01N23/00; G01N23/02; G01N23/06; G01N23/083; A; A61; A61B; A61B6/00; A61B6/40; A61B6/4035; A61B6/48; A61B6/482; A61B6/50; A61B6/505; G21; G21K; G21K1/00; G21K1/02; G21K1/04; G21K1/043; G21K1/10
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
231 words
A bone mineral content measuring apparatus comprising: (a) an X-ray generating device for generating X-rays having a continuous spectrum; (b) an X-ray detecting device for detecting the X-rays which have passed through an object to be examined; (c) a filtering device including at least one pair of X-ray filters which are switched over each other and provided in an X-ray beam path between said X-ray generating device and said X-ray detecting device, and a filter switching device for switching said X-ray filters, said pair of X-ray filters being composed of substances having different X-ray absorbing characteristics with K-absorption edges at different energy values which are approximately equal to each other; (d) a data analyzer for inputting the X-ray detection data from said X-ray detecting device and analyzing said data, said data analyzer including a spectrum subtracter and a bone mineral content analyzing circuit, said spectrum subtracter calculating the difference data between the X-ray detection data obtained by using one of said pair of X-ray filters and the X-ray detection data obtained by using the other of said pair of X-ray filters, said difference data being equivalent to data obtained by using a monochromatic spectrum, and said bone mineral content analyzing circuit providing the bone mineral content of said object on the basis of said difference data; and (e) a display unit for displaying the result of analysis of said data analyzer.
Claim 2
Dependent Claim
231 words
A bone mineral content measuring apparatus comprising: (a) an X-ray generating device for generating X-rays having a continuous spectrum; (b) an X-ray detecting device for detecting the X-rays which have passed through an object to be examined; (c) a filtering device including at least one pair of X-ray filters which are switched over each other and provided in an X-ray beam path between said X-ray generating device and said X-ray detecting device, and a filter switching device for switching said X-ray filters, said pair of X-ray filters being composed of substances having different X-ray absorbing characteristics with K-absorption edges at different energy values which are approximately equal to each other; (d) a data analyzer for inputting the X-ray detection data from said X-ray detecting device and analyzing said data, said data analyzer including a spectrum subtracter and a bone mineral content analyzing circuit, said spectrum subtracter calculating the difference data between the X-ray detection data obtained by using one of said pair of X-ray filters and the X-ray detection data obtained by using the other of said pair of X-ray filters, said difference data being equivalent to data obtained by using a monochromatic spectrum, and said bone mineral content analyzing circuit providing the bone mineral content of said object on the basis of said difference data; and (e) a display unit for displaying the result of analysis of said data analyzer.
Claim 3
Dependent Claim
62 words
A bone mineral content measuring apparatus according to claim 1, wherein said filtering device includes: a pair of X-ray filters for a low energy which are composed of substances having the K-absorption edges in a low energy region; and a pair of X-ray filters for a high energy which are composed of substances having the K-absorption edges in a high energy region.
Claim 4
Dependent Claim
56 words
A bone mineral content measuring apparatus according to claim 2, wherein each of said X-ray filters is formed into a sector having a predetermined angle and a combination of all the pairs of X-ray filters constitutes a circular filter disc; and said filter switching device switches said X-ray filters by the rotation of said filter disc.
Claim 5
Dependent Claim
26 words
A bone mineral content measuring apparatus according to claim 3, wherein said filter disc is rotated at a constant angular velocity for bone mineral content measurement.
Claim 6
Dependent Claim
54 words
A bone mineral content measuring apparatus according to claim 3, wherein one of said pair of X-ray filters for a low energy is composed of Gd, the other being composed of Ce; and one of said pair of X-ray filters for a high energy is composed of Pb, the other being composed of Au.
Claim 7
Dependent Claim
132 words
A bone mineral content measuring apparatus according to claim 1, wherein said filtering device includes: a first pair of X-ray filters for a low energy which are composed of substances having the K-absorption edges in a low energy region; a second pair of X-ray filters for a low energy which are composed of said first pair of X-ray filters for a low energy overlaid with an X-ray attenuating substance having a predetermined thickness; a first pair of X-ray filters for a high energy which are composed of substances having the K-absorption edges in a high energy region; and a second pair of X-ray filters for a high energy which are composed of said first pair of X-ray filters for a high energy overlaid with an X-ray attenuating substance having a predetermined thickness.
Claim 8
Dependent Claim
56 words
A bone mineral content measuring apparatus according to claim 6, wherein each of said X-ray filters is formed into a sector having a predetermined angle and a combination of all the pairs of X-ray filters constitutes a circular filter disc; and said filter switching device switches said X-ray filters by the rotation of said filter disc.
Claim 9
Dependent Claim
26 words
A bone mineral content measuring apparatus according to claim 7, wherein said filter disc is rotated at a constant angular velocity for bone mineral content measurement.
Claim 10
Dependent Claim
73 words
A bone mineral content measuring apparatus according to claim 7, wherein one of said first pair of X-ray filters for a low energy is composed of Gd, the other being composed of Ce; one of said first pair of X-ray filters for a high energy is composed of Pb, the other being composed of Au; and said X-ray attenuating substance contains at least one selected from the group consisting of copper and brass.
Claim 11
Dependent Claim
31 words
A bone mineral content measuring apparatus according to claims 3 or 7, wherein said data analyzer includes an average bone mineral density analyzing circuit for obtaining an average bone mineral density.
Claim 12
Dependent Claim
29 words
A bone mineral content measuring apparatus according to claims 3 or 7, wherein said filtering device is disposed between said X-ray generating device and said object to be examined.
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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) | 1996-04-19 | 1996-10-19 | 1997-04-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-04-19 | 2000-10-19 | 2001-04-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-04-19 | 2004-10-19 | 2005-04-20 | $7700.00 | Window Closed / Lapsed |