A quantitative study of in vivo protoporphyrin IX fluorescence build up during occlusive treatment phases
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Background: Topical photodynamic therapy (PDT) is a non-invasive light based therapy used to treat non-melanoma skin cancer (NMSC) and dysplasia. During PDT, the light sensitive molecule protoporphyrin IX (PpIX) is activated, resulting in the production of singlet oxygen, which subsequently leads to cell death. PpIX is metabolised from a topically applied pro-drug and the strong fluorescence signal associated with PpIX can be utilised as an indicator of the amount of PpIX present within the tumour tissue. In this work we measure the build up PpIX during the occlusive treatment phase and investigate how the PpIX production rate is affected by different lesion and patient characteristics. Methods : Fluorescence measurements were used to investigate the build up of PpIX within the tumour tissue during the 3 hour long occlusive treatment prior to irradiation. The study included in vivo measurements of 38 lesions from 38 individual patients. Actinic keratosis (AK) and basal cell carcinoma (BCC) were the lesion types included in this study. The resulting data from the study was analysed using generalised linear mixed effects models. Results : It was found that the surface fluorescence signal linearly increased with occlusive treatment time. The predictive models suggest that there is a significant difference in PpIX production between lesion location, however no significant difference is demonstrated between different lesion types, gender and skin type. Conclusions : The study extends and supports previous knowledge of PpIX production during the occlusive treatment phase.
Campbell , C L , Brown , C T A , Wood , K , Salvio , A G , Inada , N M , Bagnato , V S & Moseley , H 2017 , ' A quantitative study of in vivo protoporphyrin IX fluorescence build up during occlusive treatment phases ' Photodiagnosis and Photodynamic Therapy , vol 18 , pp. 204-207 . DOI: 10.1016/j.pdpdt.2017.02.004
Photodiagnosis and Photodynamic Therapy
© 2017, Elsevier BV. This work has been made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at www.sciencedirect.com / https://doi.org/10.1016/j.pdpdt.2017.02.004
C L Campbell acknowledges financial support from an UK EPSRC PhD studentship (EP/K503162/1), the Alfred Stewart Trust, the Russell trust award, the Santander mobility award and the FAPESP CEPOF grant 2013/07276.
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