Background: Singlet oxygen (1O2) is a key therapeutic molecule in photodynamic therapy (PDT). Quantitation of 1O2 luminescence is important for monitoring and optimizing PDT process. Objective: The aim of this study was to evaluate a custom-built superconducting strip single photon detector (SSPD)-based time-resolved photon counting system for 1O2 luminescence detection. Materials and Methods: The wavelength responses of optical collection system were verified by a spectrum analyzer. A dual-channel signal generator simulates pulsed signals of different frequencies were used to verify the circuit system. 1O2 luminescence generated by the photoexcitation of Rose Bengal solution was examined. Results: The 1O2 detection system could transmit photons of 1270 nm and the time-resolved system showed the response down to the nanosecond range and was capable of converting the different time responses into a square wave signal. When 10 μM aqueous and methanolic RB solutions were excited with a 20 mW 532 nm laser the measured 1O2 lifetimes were 2.93±0.37 μs and 9.45±0.83 μs, respectively. At the same concentration, when the excitation power increased the number of singlet oxygen produced per unit of time also increased. Conclusions: The custom-built SSPD-based 1O2 detection system provides a reliable and sensitive means for the quantitation of 1O2 luminescence generated from PDT process.
Background and objectives: Dermatoscope is an important optical tool for dermatologists. Its illumination system is a key component for high quality visual observation and digital photography. The aim of this study was to evaluate the illumination system of a high-end handhold dermatoscope. Materials and Methods: DermLite DL5 was used for this study. The dermatoscope equipped with sophisticated illumination system for visualization under white, yellow and ultraviolet (UV) light with or without the use of polarization. A fiber optic spectrometer was used to measure the spectra of each lighting mode. A handhold spectrometer was used to measure the color temperature, luminance and chromatic aberration of various lighting conditions under non-polarized, cross-polarized and parallel-polarized modes. The uniformity of each lighting condition was analyzed by pixel analysis of projected digital images. Results: The peak wavelength of the UV LEDs was 377 nm and the full width at half maximum (FWHM) was 21.27 nm. The peak wavelength of the yellow LEDs was 591 nm and the FWHM was 15.5 nm. The color temperature of white LEDs was over 9000 k in several modes, whereas the color temperature of the yellow LEDs varied widely and the color temperature of mixed lighting remained stable at 5000 k. The uniformity of white, yellow and mixed lighting was less than ±10%. Conclusions: The designed higher color temperature of the tested handhold dermatoscope can accommodate the physician's view of skin blood vessels. Good uniformity under different lighting and viewing modes not only satisfies the human eye but also ensure the high quality of dermatoscope digital image of the skin.
Dermoscopy is a useful tool for observing the vascular profile of port-wine stain (PWS) birthmarks. However, due to the complicity of the vascular profile, there is a lack of consensus on the classification of dermoscopic features of PWS vessels. This study investigated the potentials of deep learning-assisted methods in the classification of dermoscopy image-based of PWS vascular profiles. The classified images were used as training samples, and the RegNet network with better classification effect was selected to establish the migration learning method. The results showed that the accuracy of the RegNet network on the validation set was 82.63%. The preliminary study suggests that deep learning assisted PWS vascular contour type classification is feasible.
Hemporfin is asecond generation photosensitizerand has been used in combination with laser and LED to treat vascular and cancerousdiseases in China. In this study, four different light sources were evaluated for Hemoporfin PDT. Photobleaching experiments were carried out by exposing Hemoporfin solution to green diode laser, red diode laser, green LED, and red LED, respectively, under the same power density (30 mW/cm2) for different lengths of time. Hemoporfin fluorescence was measured before and after light exposure. Photobleaching kinetics showed the order of greenlaser > green LED > red laser> red LED. This study suggests that all tested light sources could be used for Hemoporfin PDTbut the power density and exposure time of different light sources need to be adjusted in order to achieve the same levels of photodynamic effect.
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