Philips BiliChek Manual Del Usuario página 8

By utilizing known spectral characteristics of each component, the
contribution to the total OD can be sequentially subtracted until
bilirubin is all that is remaining.
Jacques, S., Saidi, Il, Ladner, Al, and D. Oelberg. Developing an optical fiber reflectance
1
spectrometer to monitor bilirubinemia in neonates.
Each of these components have also been considered in the
development of the algorithm by which the BiliChek computes the
bilirubin measurement. By measuring the intensity of the reflected
light at more than 100 individual wavelength bands across the visible
spectrum, a spectral analysis can be performed. By normalizing against
a reference standard, the BiliCal, the variations over time of the bulb
and the photo-detectors are eliminated. The peak absorption of the
bilirubin at approximately 460 nm is measured by subtracting the
absorption of the other components from the total skin absorption.
This is represented by the equation below.
OD = OD - OD
bili total mel
The absorption of light by a molecule is proportional to its
concentration. Therefore, the absorption of bilirubin, as calculated
above, is proportional to the concentration of bilirubin in the
subcutaneous capillary beds and subcutaneous tissue. By subtracting
the contribution of the aforementioned components, the bilirubin
absorbance can be quantified and is correlated to the laboratory total
serum bilirubin levels.
1 SPIE Proceedings 2975, Laser-Tissue Interactions, San Jose, CA Feb. 1997. 1-7.
- OD - OD
heme derm
Non-Invasive Skin Spectral
Components
1
Chapter 1. Introduction
3