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Research Papers: Therapeutic

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 Affiliations
Ronan M. Valentine

University of St. Andrews, School of Physics and Astronomy, North Haugh, St. Andrews, Fife KY16 9SS, United Kingdom

University of Dundee, The Photobiology Unit, Ninewells Hospital & Medical School, Dundee DD1 9SY, United Kingdom

C. Tom A. Brown, Kenny Wood

University of St. Andrews, School of Physics and Astronomy, North Haugh, St. Andrews, Fife KY16 9SS, United Kingdom

Harry Moseley, Sally Ibbotson

University of Dundee, The Photobiology Unit, Ninewells Hospital & Medical School, Dundee DD1 9SY, United Kingdom

J. Biomed. Opt. 16(4), 048002 (April 04, 2011). doi:10.1117/1.3562540
History: Received May 17, 2010; Revised January 21, 2011; Accepted February 10, 2011; Published April 04, 2011; Online April 04, 2011
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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.

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© 2011 Society of Photo-Optical Instrumentation Engineers (SPIE)

Citation

Ronan M. Valentine ; C. Tom A. Brown ; Harry Moseley ; Sally Ibbotson and Kenny Wood
"Monte Carlo modeling of in vivo protoporphyrin IX fluorescence and singlet oxygen production during photodynamic therapy for patients presenting with superficial basal cell carcinomas", J. Biomed. Opt. 16(4), 048002 (April 04, 2011). ; http://dx.doi.org/10.1117/1.3562540


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