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Optical non-invasive technique for vessel imaging: II. A simplified photon diffusion analysis
Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
Linköping University, Department of Mathematics. Linköping University, The Institute of Technology.
Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
2000 (English)In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 45, no 12, 3779-3792 p.Article in journal (Refereed) Published
Abstract [en]

The purpose of this paper is to explain theoretically the origin of previously presented experimental results by an optical non-invasive method using NIR for imaging blood vessels based on a specific combination of several physical parameters. The theoretical model is based on the diffusion approximation derived from the transport theory deep in a bulk tissue. An analytical solution was obtained describing photon behaviour under certain conditions during vessel identification. The modelled results indicate that the vessel identification facility depends upon source-detector separation and vessel depth, and does not depend essentially on the radiant power from the light source. The solution offers a relatively simple theoretical explanation of the experimental results and can be applied to several other clinical applications using similar technical solutions.

Place, publisher, year, edition, pages
2000. Vol. 45, no 12, 3779-3792 p.
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:liu:diva-32636DOI: 10.1088/0031-9155/45/12/319Local ID: 18553OAI: oai:DiVA.org:liu-32636DiVA: diva2:253459
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2017-12-13
In thesis
1. Photon propagation in tissue and in biological fluids: applied for vascular imaging and haemodialysis monitoring
Open this publication in new window or tab >>Photon propagation in tissue and in biological fluids: applied for vascular imaging and haemodialysis monitoring
2003 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis focuses on the photon propagation in tissue and in biological fluids in two main areas: (1) optical vessel imaging and (2) monitoring solutes removed in haemodialysis.

The aim of the optical vessel imaging study was to design and assess a new optical scanning technique for vessel imaging using NIR radiation. The results indicated that veins could be determined at three vascular levels (superficial, intermediate and deep) down to 3 mm. Moreover, experimental results demonstrated that the vessel imaging facility depends upon source-detector separation, relative position, and vessel depth and does not depend essentially on the radiant power from the light source. After vessel imaging the technique can potentially be used to monitor several physiological parameters on a selected vascular bed (e.g. local blood flow, oxygen saturation).

The theoretical model, based on the diffusion approximation, was developed to explain theoretically the origin of experimental results. An analytical solution was obtained describing photon propagation under certain conditions during vessel identification. The modelled results confirmed previously obtained experimental results.

A new optical method for monitoring solutes in a spent dialysate using absorption of UV-radiation was developed. The obtained on-line UV-absorbance curve demonstrates the possibility to follow a single haemodialysis session continuously and to monitor deviations in the dialysator performance using UV-absorbance. The experimental results indicated that the UV-absorbance correlates well to the concentration of several solutes known to accumulate in dialysis patients indicating that the technique can be used to estimate the removal of retained substances.

Furthermore, a clinical study suggested that the delivered dialysis dose in terms of the traditional urea Kt/V could be estimated by on-line measurement of the UV-absorption in the spent dialysate. This means that the UV-method may add a new methodology for improvement of the quality and adequacy of the dialysis.

An investigation of the wavelength dependence of the UV-absorbance when monitoring different compounds in the dialysate showed that the UV-absorbance correlates well to several small molecular weight solutes ( < 200 D), around 290-310 nm. The highest contribution to the total absorbance from the observed compounds was confirmed in this wavelength region. The results indicated, that it might be possible to measure the elimination of several substances that are retained in the uraemic patients and with potential clinical significance. From thisviewpoint, the UV-absorbance monitoring technique may become a more universal method to ensure the quality and adequacy of the dialysis.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet, 2003. 164 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 818
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-24500 (URN)6624 (Local ID)91-737-3638-4 (ISBN)6624 (Archive number)6624 (OAI)
Public defence
2003-05-06, Berzeliussalen, Universitetssjukhuset, Linköping, 09:00 (Swedish)
Opponent
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2013-01-29

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Fridolin, IvoHansson, KurtLindberg, Lars-Göran

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