ISSN:
1435-604X
Keywords:
Photodynamic therapy
;
Lasers
;
Light dosimetry
;
Skeletal muscle
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
,
Physics
,
Technology
Notes:
Abstract For precise light dosimetry in photodynamic therapy (PDT), the light penetration characteristics of the tissue concerned need to be assessed. Several attenuation coefficients have so far been measured using 633 nm wavelength red light and human tissue obtained from autopsy or surgery. However, the validity of such ex vivo derived values remains uncertain, and hence is evaluated further in this study. Using a rat thigh muscle model, the tissue transmittance of 633 nm red light was compared between in vivo and ex vivo. Transmittance (in vivo) following preliminary injection of 40 mg kg−1 haematoporphyrin derivative (HPD) was also measured in muscle and liver. The effective attenuation coefficient (⌆eff) ex vivo in muscle was 0.98±0.06 mm−1 and in vivo 0.97 ± 0.05 mm−1. Values agreed within experimental error indicating that in this tissue, changes from in vivo to post-mortem produced no alteration in optical penetration at 633 nm. Preliminary injection of HPD did not influence the penetration depth in muscle although significant changes were observed in an organ of high porphyrin avidity, the liver (0.68±0.08 mm vs 0.40±0.08 mm with HPD). Until techniques for in vivo measurements of light attenuation coefficient become available, the use of ex vivo derived values with 633 nm wavelength light would seem appropriate.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02032597
Permalink
