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Titolo:
SWITCHING FROM DXA PENCIL-BEAM TO FAN-BEAM .1. STUDIES IN-VITRO AT 4 CENTERS
Autore:
EIKEN P; BARENHOLDT O; JENSEN LB; GRAM J; NIELSEN SP;
Indirizzi:
HILLEROD SYGEHUS,DEPT CLIN PHYSIOL,HELSEVEJ 2 DK-3400 HILLEROD DENMARK HILLEROD SYGEHUS,DEPT CLIN PHYSIOL DK-3400 HILLEROD DENMARK KOMMUNE HOSP COPENHAGEN,CTR OSTEOPOROSIS COPENHAGEN DENMARK ODENSE UNIV HOSP,DEPT MED M DK-5000 ODENSE DENMARK
Titolo Testata:
Bone
fascicolo: 6, volume: 15, anno: 1994,
pagine: 667 - 670
SICI:
8756-3282(1994)15:6<667:SFDPTF>2.0.ZU;2-H
Fonte:
ISI
Lingua:
ENG
Soggetto:
X-RAY ABSORPTIOMETRY;
Keywords:
SPINE; BONE DENSITOMETRY; DUAL X-RAY ABSORPTIOMETRY; BONE MINERAL CONTENT; BONE MINERAL DENSITY;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
11
Recensione:
Indirizzi per estratti:
Citazione:
P. Eiken et al., "SWITCHING FROM DXA PENCIL-BEAM TO FAN-BEAM .1. STUDIES IN-VITRO AT 4 CENTERS", Bone, 15(6), 1994, pp. 667-670

Abstract

The performance of the Hologic QDR-2000 DXA osteoden-sitometer was critically evaluated at four centers, using at all four centers one boneequivalent humanoid spine phantom supplied by the manufacturer. Results were compared with results from Hologic QDR-1000/W using that phantom tested at the same centers. It appears that the concept of fan-beamscanning-as used in the QDR-2000: a fan-beam, a linear array detectorabove the phantom, and an x-ray tube located rather close to the spine below the phantom-creates problems due to the magnification effect of the fan beam. The effect of decreasing the distance between the ''vertebrae''' of the phantom and the couch are: bone mineral content (BMC) increases by 2.8% per cm, projected area (Area) by 2.8% per cm, and bone mineral density (BMD) is unchanged. When QDR-1000/W is upgraded to QDR-2000, BMD is relatively constant, but there are shifts of BMC and Area which are partly due to the magnification effect of the fan-beam. Replacement of a QDR-1000/W with a QDR-2000 can invalidate longitudinal measurements, even for BMD, unless the proportionality factors ofthe QDR-2000 are checked and, if necessary, changed. This is true forswitching from QDR-1000/W to pencil-beam mode of QDR-2000 or to fan-beam mode of QDR-2000. Even with pencil-beam mode, the long-term precision error with phantoms is higher for QDR-2000 than for QDR-1000/W (for BMD, 0.47% versus 0.35%).

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 04/12/20 alle ore 18:02:58