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Cross-calibration of liquid and solid QCT calibration standards: corrections to the UCSF normative dataQuantitative computed tomography (QCT) has been shown to be a precise and sensitive method for evaluating spinal bone mineral density (BMD) and skeletal response to aging and therapy. Precise and accurate determination of BMD using QCT requires a calibration standard to compensate for and reduce the effects of beam-hardening artifacts and scanner drift. The first standards were based on dipotassium hydrogen phosphate (K2HPO4) solutions. Recently, several manufacturers have developed stable solid calibration standards based on calcium hydroxyapatite (CHA) in water-equivalent plastic. Due to differences in attenuating properties of the liquid and solid standards, the calibrated BMD values obtained with each system do not agree. In order to compare and interpret the results obtained on both systems, cross-calibration measurements were performed in phantoms and patients using the University of California San Francisco (UCSF) liquid standard and the Image Analysis (IA) solid standard on the UCSF GE 9800 CT scanner. From the phantom measurements, a highly linear relationship was found between the liquid- and solid-calibrated BMD values. No influence on the cross-calibration due to simulated variations in body size or vertebral fat content was seen, though a significant difference in the cross-calibration was observed between scans acquired at 80 and 140 kVp. From the patient measurements, a linear relationship between the liquid (UCSF) and solid (IA) calibrated values was derived for GE 9800 CT scanners at 80 kVp (IA = [1.15 x UCSF] - 7.32).(ABSTRACT TRUNCATED AT 250 WORDS).
Document ID
20050000536
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Faulkner, K. G.
(University of California San Francisco)
Gluer, C. C.
Grampp, S.
Genant, H. K.
Date Acquired
August 22, 2013
Publication Date
January 1, 1993
Publication Information
Publication: Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA
Volume: 3
Issue: 1
ISSN: 0937-941X
Subject Category
Aerospace Medicine
Funding Number(s)
CONTRACT_GRANT: AR 27926
Distribution Limits
Public
Copyright
Other
Keywords
NASA Program Space Physiology and Countermeasures
NASA Discipline Number 26-10
NASA Discipline Musculoskeletal
Non-NASA Center

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