Modeling PpIX effective light fluence at depths into the skin for PDT dose comparison
| Autor: | Robert E. LeBlanc, M. Shane Chapman, Kayla Marra, Brian W. Pogue, Ethan P. M. LaRochelle, Edward V. Maytin |
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| Rok vydání: | 2019 |
| Předmět: |
Skin Neoplasms
Time Factors Materials science medicine.medical_treatment Monte Carlo method Biophysics Irradiance Protoporphyrins Photodynamic therapy Dermatology Models Biological Fluence Optics Reference Values medicine Humans Prodrugs Pharmacology (medical) Skin Photosensitizing Agents Cell Death Dose-Response Relationship Drug business.industry Dose comparison Actinic keratosis Treatment method Aminolevulinic Acid medicine.disease Keratosis Actinic Photochemotherapy Oncology Effective surface business Monte Carlo Method |
| Zdroj: | Photodiagnosis and Photodynamic Therapy. 25:425-435 |
| ISSN: | 1572-1000 |
| DOI: | 10.1016/j.pdpdt.2019.01.022 |
| Popis: | Background Daylight-activated PDT has seen increased support in recent years as a treatment method for actinic keratosis and other non-melanoma skin cancers. The inherent variability observed in broad-spectrum light used in this methodology makes it difficult to plan and monitor light dose, or compare to lamp light doses. Methods The present study expands on the commonly used PpIX-weighted effective surface irradiance metric by introducing a Monte Carlo method for estimating effective fluence rates into depths of the skin. The fluence rates are compared between multiple broadband and narrowband sources that have been reported in previous studies, and an effective total fluence for various treatment times is reported. A dynamic estimate of PpIX concentration produced during pro-drug incubation and treatment is used with the fluence estimates to calculate a photodynamic dose. Results Even when there is up to a 5x reduction between the effective surface irradiance of the broadband light sources, the effective fluence below 250 μm depth is predicted to be relatively equivalent. An effective threshold fluence value (0. 70 J e f f / c m 2 ) is introduced based on a meta-analysis of previously published ALA-PpIX induced cell death. This was combined with a threshold PpIX concentration (50 nM) to define a threshold photodynamic dose of 0.035 u M J e f f / c m 2 . Conclusions The threshold was used to generate lookup tables to prescribe minimal treatment times to achieve depth-dependent cytotoxic effect based on incubation times and irradiance values for each light source. |
| Databáze: | OpenAIRE |
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