| Autor: |
W, Verkruysse, A M, Nilsson, T E, Milner, J F, Beek, G W, Lucassen, M J, van Gemert |
| Rok vydání: |
1998 |
| Předmět: |
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| Zdroj: |
Photochemistry and photobiology. 67(3) |
| ISSN: |
0031-8655 |
| Popis: |
Optical properties are important parameters in port wine stain laser treatment models. In this study we investigated whether changes in blood optical properties occur during a 0.5 ms laser pulse. Blood from three volunteers was irradiated in vitro with laser pulses (radiant exposure 2-12 J cm-2, wavelength 586 nm, pulse length 0.5 ms). Reflection and transmission coefficients, measured using double integrating spheres, decreased slightly during the first part of the pulse. At 2.9 J cm-2 radiant exposure, the reflectance increased, independent of total radiant exposure of the pulse. This was caused by blood coagulation. A second sudden increase in reflection and a significant increase in transmission occurred near 6.3 J cm-2 and was accompanied by a "popping" sound, indicating rapid expansion of bubbles due to blood vaporization. A multilayered model of blood was used to fit calculated transmission coefficient curves to the measurements and determine temperature-dependent optical blood absorption. Heat diffusion was shown to be of minor importance. A 2.5-fold increase in absorption for temperatures increasing from 20 to 100 degrees C, accurately describes transmission coefficients measured up to 2.9 J cm-2. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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