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Typus
BauernOpfer
Bearbeiter
Graf Isolan
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Untersuchte Arbeit:
Seite: 3, Zeilen: 25ff.
Quelle: Elwell and Hebden 1999
Seite(n): 1 (Internetversion), Zeilen: -
2.1.b Near-infrared Spectroscopy (NIRS)

All of us are exposed to optical (i.e. visible and near-infrared) radiation from the sun and other sources throughout our lives. Assuming that our eyes are protected from excessive intensity and our skin from the ultraviolet content of the sunlight, we accept this exposure in the knowledge that it is perfectly safe. Unlike x-rays, optical photons are insufficiently energetic to produce ionization, and unless light is concentrated to such a high degree that it burns the skin, optical radiation offers no significant hazard. The diagnostic potential of optical methods has been widely known since Jöbsis [Jöbsis, 1977] first demonstrated that transmittance measurements of near-infrared (NIR) radiation could be used to monitor the degree of oxygenation of certain metabolites. This led to the development and increasingly widespread use of clinical near-infrared spectroscopy (NIRS), which offers a safe, non-invasive means of monitoring cerebral function at the bedside without the use of radioisotopes or other contrast agents [Cope and Deply, 1988].

Human tissues contain a variety of substances whose absorption spectra at NIR wavelengths are well defined and which are present in sufficient quantities to contribute significant attenuation to measurements of transmitted light. The concentration of some absorbers, such as water, melanin, and bilirubin, remain virtually constant with time. However, some absorbing compounds, such as oxygenated hemoglobin (HbO2), deoxyhemoglobin (Hb) and oxidized cytochrome oxidize (CtOx), have concentrations in tissue which are strongly linked to tissue oxygenation and metabolism. Increasingly dominant absorption by water at longer wavelengths [limits spectroscopic studies to less than about 1000 nm.]


[Cope and Deply, 1988]

COPE M. AND DEPLY D.T. 1988. “A System for Long-term Measurement of Cerebral Blood and Tissue Oxygenation in Newborn Infants by Near-infrared Tranillumination”. In Medical and Biological Engineering and Computation. 32: 1457-1467.

[Jöbsis, 1977]

JÖBSIS F.F. 1977. „Noninvasive, Infrared Monitoring of Cerebral and Myocardial Oxygen Sufficiency and Circulatory Parameters “ In Science, 198(4323): 1264-1267.

Near Infrared Spectroscopy

By Clare Elwell and Jem Hebden

Introduction

All of us are exposed to optical (i.e. visible and near-infrared) radiation from the sun and other sources throughout our lives. Assuming our eyes are shielded from excessive intensity, and our skin is protected from the ultraviolet content of sunlight, we accept this exposure in the knowledge that it is perfectly safe. Unlike x-rays, optical photons are insufficiently energetic to produce ionisation, and unless light is concentrated to such a high degree that it causes burning to the skin, optical radiation offers no significant hazard. The diagnostic potential of optical methods has been widely known since Jöbsis [1] first demonstrated that transmittance measurements of near-infrared (NIR) radiation could be used to monitor the degree of oxygenation of certain metabolites. This led to the development and increasingly widespread use of clinical near-infrared spectroscopy (NIRS), which offers a safe, non-invasive means of monitoring cerebral function at the bedside without the use of radioisotopes or other contrast agents [2].

Human tissues contain a variety of substances whose absorption spectra at NIR wavelengths are well defined, and which are present in sufficient quantities to contribute significant attenuation to measurements of transmitted light. The concentration of some absorbers, such as water, melanin, and bilirubin, remain virtually constant with time. However, some absorbing compounds, such as oxygenated haemoglobin (HbO2), deoxyhaemoglobin (Hb), and oxidised cytochrome oxidase (CtOx), have concentrations in tissue which are strongly linked to tissue oxygenation and metabolism. Increasingly dominant absorption by water at longer wavelengths limits spectroscopic studies to less than about 1000 nm.


1. Jöbsis, FF (1977): Science 198, 1264-1267.

2. Cope, M, and Delpy DT (1988): Med. & Biol. Eng. & Comput. 26, 289-294.

Anmerkungen

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