Determination of Threshold Dose of Photodynamic Therapy to Measure Superficial Necrosis


Autoria(s): FERRAZ, R. C. M. C.; FERREIRA, J.; MENEZES, P. F. C.; SIBATA, C. H.; SILVA JR., O. Castro e; BAGNATO, V. S.
Contribuinte(s)

UNIVERSIDADE DE SÃO PAULO

Data(s)

18/04/2012

18/04/2012

2009

Resumo

Background Data: Photodynamic therapy (PDT) involves the photoinduction of cytotoxicity using a photosensitizer agent, a light source of the proper wavelength, and the presence of molecular oxygen. A model for tissue response to PDT based on the photodynamic threshold dose (Dth) has been widely used. In this model cells exposed to doses below Dth survive while at doses above the Dth necrosis takes place. Objective: This study evaluated the light Dth values by using two different methods of determination. One model concerns the depth of necrosis and the other the width of superficial necrosis. Materials and Methods: Using normal rat liver we investigated the depth and width of necrosis induced by PDT when a laser with a gaussian intensity profile is used. Different light doses, photosensitizers (Photogem, Photofrin, Photosan, Foscan, Photodithazine, and Radachlorin), and concentrations were employed. Each experiment was performed on five animals and the average and standard deviations were calculated. Results: A simple depth and width of necrosis model analysis allows us to determine the threshold dose by measuring both depth and surface data. Comparison shows that both measurements provide the same value within the degree of experimental error. Conclusion: This work demonstrates that by knowing the extent of the superficial necrotic area of a target tissue irradiated by a gaussian light beam, it is possible to estimate the threshold dose. This technique may find application where the determination of Dth must be done without cutting the tissue.

Fundacao de Amparo Pesquisa do Estado de Sao Paulo (FAPESP)

Identificador

PHOTOMEDICINE AND LASER SURGERY, v.27, n.1, p.93-99, 2009

1549-5418

http://producao.usp.br/handle/BDPI/15279

10.1089/pho.2007.2207

http://dx.doi.org/10.1089/pho.2007.2207

Idioma(s)

eng

Publicador

MARY ANN LIEBERT INC

Relação

Photomedicine and Laser Surgery

Direitos

closedAccess

Copyright MARY ANN LIEBERT INC

Palavras-Chave #NORMAL RAT-LIVER #LIGHT DOSIMETRY #CANCER #TUMOR #MODEL #DRUG #PHOTOSENSITIZERS #PHTHALOCYANINE #WAVELENGTH #DEPENDENCE #Surgery
Tipo

article

original article

publishedVersion