BACKGROUND AND OBJECTIVE: We present a new theory of selective thermal damage of non-uniformly pigmented structures in biological tissues. Spatial separation of the heavily pigmented areas and the target requires limitation of the pigment temperature and heat diffusion from the pigmented to the targeted areas. STUDY DESIGNS/ MATERIALS AND METHODS: A concept of selective target damage by heat diffusion is presented for three target geometries: planar, cylindrical, and spherical. An in vitro experiment is described in which the dependence of thermal damage on pulsewidth at constant fluence was evaluated. RESULTS: The in vitro experiment showed that the size of the damage zone for similar hair follicles was pulsewidth-independent over a very broad range of pulsewidths (30-400 ms). We formulated a new theory (extended theory of photothermolysis) to interpret the experimental results. CONCLUSIONS: Based on this new theory, the treatment pulsewidth for non-uniformly pigmented targets is significantly longer than the target thermal relaxation time (TRT). The theory provides new recommendations for photoepilation and photosclerotherapy parameters.
BACKGROUND AND OBJECTIVE: We present a new theory of selective thermal damage of non-uniformly pigmented structures in biological tissues. Spatial separation of the heavily pigmented areas and the target requires limitation of the pigment temperature and heat diffusion from the pigmented to the targeted areas. STUDY DESIGNS/ MATERIALS AND METHODS: A concept of selective target damage by heat diffusion is presented for three target geometries: planar, cylindrical, and spherical. An in vitro experiment is described in which the dependence of thermal damage on pulsewidth at constant fluence was evaluated. RESULTS: The in vitro experiment showed that the size of the damage zone for similar hair follicles was pulsewidth-independent over a very broad range of pulsewidths (30-400 ms). We formulated a new theory (extended theory of photothermolysis) to interpret the experimental results. CONCLUSIONS: Based on this new theory, the treatment pulsewidth for non-uniformly pigmented targets is significantly longer than the target thermal relaxation time (TRT). The theory provides new recommendations for photoepilation and photosclerotherapy parameters.
Authors: Georgios E Romanos; Natalia D Gladkova; Felix I Feldchtein; Maria M Karabut; Elena B Kiseleva; Lyudmila B Snopova; Yulia V Fomina Journal: Lasers Med Sci Date: 2012-02-10 Impact factor: 3.161
Authors: Javier Moreno-Moraga; Esteban Hernández; Josefina Royo; Justo Alcolea; M Jose Isarría; Mihail Lucian Pascu; Adriana Smarandache; Mario Trelles Journal: Lasers Med Sci Date: 2012-08-11 Impact factor: 3.161
Authors: Daniel Thaysen-Petersen; Andres M Erlendsson; J F Nash; Frank Beerwerth; Peter A Philipsen; Hans C Wulf; Merete Haedersdal Journal: Lasers Med Sci Date: 2015-08-22 Impact factor: 3.161
Authors: Javier Moreno-Moraga; Mihail L Pascu; Justo M Alcolea; Adriana Smarandache; Josefina Royo; Fernández David; Mario A Trelles Journal: Lasers Med Sci Date: 2019-02-01 Impact factor: 3.161