Heesung Kang

Evaluation of Laser Beam Profile in Soft Tissue Due to Compression, Glycerol, and Micro-Needling

Various methods have been suggested to enhance photon density in biological tissues in an attempt to maximize the efficacy of laser therapy. In this study, the effects of tissue compression, glycerol, and micro‐needling methods on the laser beam profile (LBP) were investigated by quantitatively evaluating the spatial distribution of subsurface tissue photon density.

Fabrication of double layer optical tissue phantom by spin coating method: mimicking epidermal and dermal layer

Methodologies to fabricate a solid optical tissue phantom (OTP) mimicking epidermal thin-layer have been developed for in vitro human skin experiment. However, there are cumbersome and time-consuming efforts in fabrication process such as a custom-made casting and calculation of solvent volume before curing process. In a previous study, we introduced a new methodology based on spin coating method (SCM) which is utilized to fabricate a thin-layer OTP analogous to epidermal thickness. In this study, a double layer solid OTP which has epidermal and dermal layers was fabricated to mimic the morphological and optical similarity of human tissue. The structural characteristic and optical properties of fabricated double layer OTP were measured using optical coherence tomography and inverse adding doubling algorithms, respectively. It is expected that the new methodology based on the SCM may be usefully used in the fabrication of double layer OTP.

Low-level laser therapy using the minimally invasive laser needle system on osteoporotic bone in ovariectomized mice.

This study tested the effectiveness of low-level laser therapy (LLLT) in preventing and/or treating osteoporotic trabecular bone. Mice were ovariectomized (OVX) to induce osteoporotic bone loss. The tibiae of eight OVX mice were treated for 5 days each week for 2 weeks by LLLT (660 nm, 3 J) using a minimally invasive laser needle system (MILNS) which is designed to minimize loss of laser energy before reaching bone (LASER group). Another eight mice received a sham treatment (SHAM group). Structural parameters of trabecular bone were measured with in vivo micro-computed tomography images before and after laser treatment. After LLLT for 2 weeks, the percentage reduction (%R) was significantly lower in BV/TV (bone volume fraction) and Tb.N (trabecular number, p<0.05 and p<0.05) and significant higher in Tb.Sp (trabecular separation) and SMI (structure model index, p<0.05 and p<0.05) than in the SHAM group. The %R in BV/TV at sites directly treated by LLLT was significantly lower in the LASER group than the SHAM group (p<0.05, p<0.05). These results indicated that LLLT using MILNS may be effective for preventing and/or treating trabecular bone loss and the effect may be site-dependent in the same bone.

Optical polarimetry probe system for glucose concentration monitoring

Over the last two decades, optical polarimetry method has been applied for glucose concentration monitoring in biological media such as aqueous humor and cell culture media as a non-invasive alternative method. Compared to glucose analyzer and electronic analyte sensor, the advantages of polaimetry method are non-ionizing radiation to interrogate the sample, non-interference with the sample, needless of consumable reagents, use of readily available sources, and prospect of miniaturizing the optics. Commercial polarimeter is widely used to measure the concentration of chemical compounds with optical activity. However, this device was based on off-line measurement so that it needs sample extraction process to measure the concentration of sample. This process does not reflect the real-time status of sample concentration and sample contamination can be occurred during sample extraction when applied to cell culture process. In polarimetry method, the measurement sensitivity can be controlled by varying optical path length. However, in current polarimeter, the sample cell should be exchanged to vary the optical path length. This process is a time consuming and might cause sample contamination in cell culture process. Therefore, it is necessary to develop a new polarimetry method which can measure the real-time status of sample concentration without sample extraction. In this paper, we introduce a new polarimetry probe system which might be utilized to monitor glucose concentration during cell culture process. It was designed to have variable optical path lengths to control the optical rotation angle of polarized light. We describe the feasibility of the system and the preliminary results.

Development of an Optical Tissue Clearing Laser Probe System

Although low-level laser therapy (LLLT) has been a valuable therapeutic technology in the clinic, its efficacy may be reduced in deep tissue layers due to strong light scattering which limits the photon density. In order to enhance the photon density in deep tissue layers, this study developed an optical tissue clearing (OTC) laser probe (OTCLP) system which can utilize four different OTC methods: 1) tissue temperature control from 40 to

Characterization of a new acne vulgaris treatment device combining light and thermal treatment methods

10^{\circ}C

Real-time measurement of skin erythema variation by negative compression: pilot study.

; 2) laser pulse frequency from 5 to 30 Hz; 3) glycerol injection at a local region; and 4) a combination of the aforementioned three methods. The efficacy of the OTC methods was evaluated and compared by investigating laser beam profiles in ex-vivo porcine skin samples. Results demonstrated that total (peak) intensity at full width at half maximum of laser beam profile when compared to control data was increased: 1) 1.21(1.39)-fold at

Comparison of a digital color and hyper-spectral, camera for dental plaque detection

10^{\circ}C

Observation of vasculature alternation by intense pulsed light combined with physicochemical methods

; 2) 1.22 (1.49)-fold at a laser pulse frequency of 5 Hz; 3) 1.64 (2.41)-fold with 95% glycerol injection; 4) 1.86 (3.4)-fold with the combination method. In conclusion, the OTCLP system successfully improved the laser photon density in deep tissue layers and may be utilized as a useful tool in LLLT by increasing laser photon density.

A new concept of stereoscopic imaging system using single optical channel and a deflector: pilot study

Background/purpose: Conventional treatment methods for acne vulgaris have various side effects such as the development of bacterial resistance, phototoxicity, vertigo, gastro‐intestinal problems, and drug eruptions. To minimize such side effects, light and thermal methods have been alternately suggested. This study characterized a new acne vulgaris treatment device (AVTD) that combines both light and thermal methods and evaluated its clinical efficacy.