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Proceedings Paper

Weather forecast and light-tissue model based dose planning for daylight PpIX-photodynamic therapy of skin (Conference Presentation)

Paper Abstract

Photodynamic therapy (PDT) for actinic keratosis (AK) and certain non-melanoma skin cancers (NMSC) is performed with either blue light (415nm Lamp), red light (630nm LED Lamps) or with sunlight. The differences in PDT efficacy can be high when using the latter broad-spectrum activation of PpIX. The purpose of this work was to establish a predictive treatment plan approach to daylight PDT which incorporated both local weather forecast information as well as prediction of wavelength-depth dependence upon the efficacy. The concept of PpIX-weighted light fluence is now well established as a way to compare effective light doses from daylight PDT to traditional lamp PDT, but there is limited work to date considering the effects of tissue optical properties or the dynamic distribution of PpIX at depths into the tissue. Using a Monte Carlo model of light fluence in a multi-layer skin geometry we estimate the effective fluence at depth in tissue. The result of these simulations in combination with a model for PpIX production and photobleaching at a range of depths are used to generate lookup tables for the time needed to reach a specific photodynamic dose at a predicted lesion thickness. These tables are then used as the foundation of a web-based application that will better inform the dermatology team of light dosing options. GPS-derived location is used to retrieve forecasted and historical weather patterns automatically, and used as an additional input to further refine prescribed dosing of daylight-PDT. The application is currently being tested in conjunction with fluorescence dosimetry, as a method to verify and alleviate clinical variation in lesion clearing from daylight PDT.

Paper Details

Date Published: 14 August 2019
Proc. SPIE 11070, 17th International Photodynamic Association World Congress, 110705B (14 August 2019); doi: 10.1117/12.2525434
Show Author Affiliations
Ethan Philip M. LaRochelle, Thayer School of Engineering at Dartmouth (United States)
Alberto J. Ruiz, Thayer School of Engineering at Dartmouth (United States)
Robert E. LeBlanc, Dartmouth College (United States)
Edward V. Maytin, Cleveland Clinic (United States)
Tayyaba Hasan, Wellman Ctr. for Photomedicine (United States)
Massachusetts General Hospital (United States)
Harvard Medical School (United States)
M. Shane Chapman, Dartmouth College (United States)
Brian W. Pogue, Thayer School of Engineering at Dartmouth (United States)

Published in SPIE Proceedings Vol. 11070:
17th International Photodynamic Association World Congress
Tayyaba Hasan, Editor(s)

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