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Proceedings Paper

Instrument factors influencing the precision of measurement of clinical spectrometers
Author(s): Gerald E. Cohn
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Paper Abstract

Biomedical diagnostic systems perform as combinations of multiple components, each introducing an experimental uncertainty. The present study examines the uncertainty in spectrophotometric measurements of absorbance A for different models of detector response. Modeling this response provides both a quantitative estimate of the minimum relative concentration error (RCE) and limits on the operating range for which the RCE falls within specified limits. For the constant uncertainty model the operating range corresponding to RCE no greater than twice the minimum value ranges from A approximately 0.07 to A approximately 0.79. A photomultiplier-like response results in the limits 0.2 < A < 2.3. A Beer's Law model predicts that RCE contributions from sample concentration uncertainty decrease monotonically with increasing absorbance. Assay chemistry factors dominate at low A values making high precision difficult at low A.

Paper Details

Date Published: 18 August 1995
PDF: 20 pages
Proc. SPIE 2622, Optical Engineering Midwest '95, (18 August 1995); doi: 10.1117/12.216843
Show Author Affiliations
Gerald E. Cohn, Cyber Tech Applied Science, Inc. (United States)

Published in SPIE Proceedings Vol. 2622:
Optical Engineering Midwest '95
Rudolph P. Guzik, Editor(s)

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