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Journal of Biomedical Optics

Monte Carlo modeling of in vivo protoporphyrin IX fluorescence and singlet oxygen production during photodynamic therapy for patients presenting with superficial basal cell carcinomas
Author(s): Ronan M. Valentine; Christian T. A. Brown; Kenneth Wood; Harry Moseley; Sally Ibbotson
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Paper Abstract

We present protoporphyrin IX (PpIX) fluorescence measurements acquired from patients presenting with superficial basal cell carcinoma during photodynamic therapy (PDT) treatment, facilitating in vivo photobleaching to be monitored. Monte Carlo (MC) simulations, taking into account photobleaching, are performed on a three-dimensional cube grid, which represents the treatment geometry. Consequently, it is possible to determine the spatial and temporal changes to the origin of collected fluorescence and generated singlet oxygen. From our clinical results, an in vivo photobleaching dose constant, β of 5-aminolaevulinic acid-induced PpIX fluorescence is found to be 14 ± 1 J/cm2. Results from our MC simulations suggest that an increase from our typical administered treatment light dose of 75-150 J/cm2 could increase the effective PDT treatment initially achieved at a depth of 2.7-3.3 mm in the tumor, respectively. Moreover, this increase reduces the surface PpIX fluorescence from 0.00012 to 0.000003 of the maximum value recorded before treatment. The recommendation of administrating a larger light dose, which advocates an increase in the treatment time after surface PpIX fluorescence has diminished, remains valid for different sets of optical properties and therefore should have a beneficial outcome on the total treatment effect.

Paper Details

Date Published: 1 April 2011
PDF: 12 pages
J. Biomed. Opt. 16(4) 048002 doi: 10.1117/1.3562540
Published in: Journal of Biomedical Optics Volume 16, Issue 4
Show Author Affiliations
Ronan M. Valentine, Univ. of St. Andrews (United Kingdom)
Christian T. A. Brown, Univ. of St. Andrews (United Kingdom)
Kenneth Wood, Univ. of St. Andrews (United Kingdom)
Harry Moseley, Univ. of Dundee (United Kingdom)
Sally Ibbotson, Univ. of Dundee (United Kingdom)

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