Assessing the risk of skin damage due to femtosecond laser irradiation

Abstract

We irradiated freshly excised skin biopsies with four irradiation regimes usually taken for multiphoton imaging. If there is any skin damaging, it is mainly an effect similar to the damaging effects of UV-irradiation. Using fluorescent antibodies against cyclobutane-pyrimidin-dimers (CPDs) in combination with immuno-fluorescence image analysis we quantitatively compared fs-irradiation effects with UV-irradiation (solar simulator). Based on these results we are giving a risk assessment. The results show that multi photon imaging using the parameters described here is in the ballpark of damaging occurring from every day sun exposure.

Estimating the risk of squamous cell cancer induction in skin following nonlinear optical imaging

“…The findings of this study are comparable with the results of Fischer et al [28,29] who performed laser irradiation damage studies on freshly excised human skin. While the risk studies in Fischer's work were based on comparisons between DNA damage from a fs laser and from a solar simulator, the present study was based on estimating the relative risk of carcinogenesis by uniquely incorporating in vitro data into an established carcinogenic risk model for humans.…”

“…The result implies that NLO biopsy if performed at the age of 30 years, would increase the existing risk of SCC from sunlight at the age of 30 years by just 0.00061%. For the two comparable imaging regimes adopted by Fischer et al [28], the additional risk increase for skin cancer from a lifetime biopsy was found to be 0.045-0.06% for a wavelength of 750 nm. Our risk values were lower than those calculated by Fischer because the area factor (e) was not taken into account for their risk calculation.…”

“…Therefore CPD fluorescence intensity values for UVC was considered only up to 250 Jm À2 , for calibration of continuous UV against fs-laser in this risk model Among other studies that assessed the carcinogenic risk from pulsed lasers, the work of Fischer et al's was the most comparable study. In their study, 10 horizontal scans were performed per imaging site at 15 mW and 30 mW laser power at a wavelength of 750 nm [28]. While their study reported no CPD formation in irradiated human buttock skin at these doses, CPDs were detected when they performed 10 horizontal scans at 5 micron steps using a laser power of 60 mW and 150 horizontal scans at 1 micron steps increasing the laser power linearly with depth from 2 to 35 mW.…”

Photo-Induced Cell Damage Analysis for Single- and Multifocus Coherent Anti-Stokes Raman Scattering Microscopy

“…The multiphoton process possibly induces thermal stress, oxidation stress, free-radical generation, and so on. For example, the photo-induced productions of DNA such as pyrimidine dimers and pyrimidine pyrimidone photoproducts can be initiated via the absorption of ultraviolet light at C = C double bonds in DNA that corresponds to the three-photon absorption of the nearinfrared light [25][26][27][28]. Reactive oxygen species such as singlet oxygen ( light to oxygen molecules near the chromophores [29][30][31].…”

Clinical application of multiphoton tomography in combination with high‐frequency ultrasound for evaluation of skin diseases

“…A 80 MHz femtosecond titanium:sap- phire laser MaiTai (Spectra Physics, Mountain View, USA) with a tuning range of 750-850 nm, a pulse width of 80 fs, and a maximum in situ power of 2 mW (surface) to 50 mW (dermis) was employed. The laser beam was focused to a submicron spot by NA1.3 focusing optics [25,26] and moved by fast x; y galvoscanners and z piezoactuators. The signal was recorded by fast photomultipliers.…”