Quantitative optical coherence tomography of skin lesions induced by different ultraviolet B sources

Ultraviolet B (UVB) has been widely used in dermatological phototherapy. Narrowband UVB (NB-UVB), with a peak at 311 nm, is considered to be more effective than broadband UVB (BB-UVB). However, the safety of NB-UVB is controversial. In this study, we first introduced optical coherence tomography (OCT), a novel, non-invasive in vivo imaging technology, to assess the effect of NB-UVB and BB-UVB on skin. Balb/c mice dorsal skin was exposed with increasing UVB doses (1MED, 3MEDs and 5MEDs), and then OCT images of the tissues were obtained by an OCT system with 1310 nm central wavelength. Quantitative parameters (skin thickness, disruption of the entrance signal and correlation coefficient) were extracted from the OCT images. The data indicated that NB-UVB-induced skin lesions were similar to that of BB-UVB at 1MED or 3MEDs UVB. However, the skin tissues exposed with 5MEDs NB-UVB suffered from more lesions than BB-UVB. Furthermore, the persistence of skin inflammation in 3MEDs NB-UVB-induced skin tissues was much longer than that of BB-UVB (P = 0.004). In conclusion, optimized treatment time and frequency as well as close clinical monitoring should be undertaken to reduce the latent risk of NB-UVB phototherapy.