A dedicated applicator for light delivery and monitoring of PDT of intra-anal intraepithelial neoplasia

SummaryThe objective of this study was to develop an applicator for delivery of light and monitoring of photodynamic therapy (PDT) in the anal cavity for treatment of anal intraepithelial neoplasia grade III (AIN III), which can progress to invasive anal cancer.Forty-eight hours before treatment, patients participating in the study were injected with 0.03 (n = 2) or 0.075 (n = 2) mg kg−1 m-THPC. For light delivery and monitoring of PDT, an applicator based on standard anoscopy equipment was developed which facilitates, in addition to a light treatment fiber, fiber optic probes to monitor blood saturation, blood volume, fluorescence and fluence (rate) at two different locations in situ. Patients were given a light dose of 10–17 J cm−2 at a fluence rate of 45–50 mW cm−2 based on in situ measured light treatment parameters.We demonstrate that the applicator does not influence the fluence rate profile of the light treatment fiber. Furthermore this study shows the possibility of monitoring blood saturation, blood volume, fluorescence and fluence (rate) during therapeutic illumination without changing the light treatment protocol.