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- af Klinteberg, C, et al.
(author)
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Laser-induced fluorescence diagnostics of basal cell carcinomas of the skin following topical ALA application
- 1996
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In: Optical Biopsies and Microscopic Techniques, Proceedings of. - : SPIE. - 0819423289 ; 2926, s. 32-40
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Conference paper (peer-reviewed)abstract
- Fourteen patients with superficial basal cell carcinomas (BCCs) and fifteen patients with nodular BCCs were investigated by means of laser-induced fluorescence (LIF) in connection with photodynamic therapy (PDT). Topical application of delta-amino levulinic acid (ALA) was performed six hours prior to the treatment session. Fluorescence spectra were recorded, using a point-monitoring system with an excitation wavelength of 405 nm. The measurements were performed in scans over the lesion and the surrounding normal skin before application of ALA, and immediately before and after the laser treatment. The selective uptake of the photosensitiser resulted in a fluorescence intensity ratio of 2.4:1 for superficial BCCs and 2.5:1 for nodular BCCs. If the fluorescence intensity was divided by the autofluorescence, this resulted in a contrast enhancement of about a factor 6 for tumour tissue. In seven patients (five with nodular BCC and two with superficial BCC), additional fluorescence measurements were performed two and four hours following the ALA application, and two hours after the PDT procedure. Thus, the kinetics of the transformation of ACA to protoporphyrin IX (PpIX) could be followed, which indicated that the synthesis of PpIX was more rapid in the tumour than in the normal tissue. After four hours, the PpIX level inside the tumour was saturated, while there still was an accumulation in the surrounding skin. The highest contrast between tumour and normal skin was reached within two hours after the ALA application.
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- Nilsson, Annika, 1969, et al.
(author)
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Optical properties of human whole blood - Changes due to slow heating
- 1996
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In: LASER-TISSUE INTERACTION AND TISSUE OPTICS II, PROCEEDINGS OF. - : SPIE. - 0819423254 ; 2923, s. 24-34
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Conference paper (peer-reviewed)abstract
- Optical properties of human whole blood were measured in vitro, at 633 nm with a double integrating sphere set-up, The blood was kept at constant flow through a flow cell while slowly heating the blood from approximately 25 degrees C to 55 degrees C in a heat exchanger, The results show a small but distinct decrease in the g-factor of 1.7 +/- 0.6\% and a similar increase in the scattering coefficient, mu(s), of 2.9 +/- 0.6\% at approximately 45-46 degrees C. When studying the thermal effect on the blood cells under a white-light transmission microscope, the changes in the scattering properties could be correlated to a sudden change in the shape of the red blood cells, from disc-shaped to spherical, at approximately the same temperature. Furthermore, a continuous manifest increase in the absorption coefficient, mu(a), was seen with temperature rise, on average 83.8 +/- 68.1\% when reaching the temperature 50 degrees C. This might be due to heat-induced haemolysis of the red blood cells, resulting in free light absorbing haemoglobin in the surrounding plasma and thus higher effective light absorption.
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