Impacts of vascular diameter and depth on singlet oxygen luminescence imaging in tissue simulating phantom

Abstract

Singlet oxygen ( 1 O 2 ) is the primary cytotoxic production in type-II photodynamic therapy (PDT). The correlation between 1 O 2 generation and PDT efficacy during treatment has received considerable attention. The direct detection of 1 O 2 luminescence is the gold standard for 1 O 2 identification. However, the intensity of 1 O 2 luminescence could be influenced by tissue optical properties, location and morphology of lesion, especially for vascular targeting PDT. In this study, the impacts of vascular diameter and depth on 1 O 2 luminescence imaging have been investigated in tissue simulating phantom. A near-IR sensitive InGaAs camera with adaptive optics and CW laser 532 nm were used for fast imaging of 1 O 2 luminescence. Rose Bengal (RB) was used as photosensitizer to generate 1 O 2 during photosensitization. Intralipid was diluted with different concentrations in order to establish the scattering properties of tissues. The capillary tubes, containing solution of RB, with varied diameters from 0.1 to 0.9 mm were used to simulate the vascular with the depth varied from 0 to 5 mm in phantom. The preliminary results indicate that the profile range ratio of 1 O 2 luminescence images are negatively correlated to the diameter of capillary tube, and the attenuation of intensity of 1 O 2 luminescence is non-linear with the increase of depth.