title: Simulation of fractionated and continuous irradiation in photodynamic therapy: study the differences between photobleaching and singlet oxygen dose deposition.
abstract: This study aims to compare the continuous irradiation with fractionated irradiation for photodynamic therapy (PDT) of solid tumors with intraperitoneally administered 5-aminolaevulinic acid (ALA). Therefore, considering the complex physiology of solid tumors and in order to inform simulations well, we did experiments on Balb/c mice using non-invasive fluorescence spectroscopy to have a feedback of protoporphyrin IX (PpIX) concentration in tumor just before irradiation and during treatment. PDT simulations were performed based on delivery of 36 J cm(-2) total laser energy (630 nm) at the fluence rate of 40 mW cm(-2) either for continuous or fractionated illumination. Based on the calculated amounts of (1)O(2) dose deposition and comparing these amounts with the 5 × 10 (18) molecules cm(-3) threshold of reacting (1)O(2), simulation results demonstrate that fractionated illumination with alternating light and dark periods of 60 s improved the tumor response further for PpIX-mediated PDT.
authors: Department of Electrical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran. Naghavi@ieee.org
authors: Nadia
authors: N
authors: Naghavi
authors: Mohammad Hossein
authors: MH
authors: Miranbaygi
authors: Ameneh
authors: A
authors: Sazgarnia
mesh_terms: D000622:Aminolevulinic Acid / Q000493:pharmacokinetics / Q000494:pharmacology; D000818:Animals; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000378:metabolism; D003198:Computer Simulation; D051379:Mice; D008807:Mice, Inbred BALB C; D008954:Models, Biological; D038761:Photobleaching; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000493:pharmacokinetics / Q000494:pharmacology; D011524:Protoporphyrins / Q000493:pharmacokinetics; D026082:Singlet Oxygen / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
chemical_list: D017319:Photosensitizing Agents; D011524:Protoporphyrins; D026082:Singlet Oxygen; D000622:Aminolevulinic Acid; C028025:protoporphyrin IX