فصلنامه لیزر در پزشکی
سال هفتم شماره 1 (پیاپی 34، بهار 1389)

Many different results reported about low level laser therapy effects on inflammatory, proliferation, and remodeling phases of repair. Purpose of this study was to evaluate the influences of He-Ne632/8 nm & Ga-As 904nm low level laser irradiation on biomechanical parameters and decrease of surface wound area in full thickness wounds of Rats. 30 male Sprague-dawly rats (200-350 g) were randomly divided into three groups: Ga-As laser, He-Ne laser and control group (10 animals in each group). A 2.5 cm full thickness skin incision was made on animals’ thoracic dorsal region. Up to 21st day of healing, the treatment were done by Ga-As or He-Ne laser with energy density of 2 j/cm2 as every other day. After each treatment session, wound surface area was measured and at 21st day, uniaxial tensile test was made. After recording of load-deformation and stress-strain curves, biomechanical parameters (Stress, Strain, Tensile strength, Elastic modulus, Area under load-deformation curve (were obtained. Both laser groups have faster decrease of wound surface area in comparison with control group (P<0.05). the increase of stress, strain, tensile strength (Fmax), deformation and area under curve(energy absorption) was shown in two laser groups in comparison with control group, but these incremental effects were significant only in Ga-As group (P<0.05). It seems that Ga-As laser is more effective for improvement of wound biomechanical parameters.

Psoriasis is an auto immune skin disease which afflicts skin by the red plaques that usually are accompanied the silvery-white scales. Various medical treatments are used for this disease that have different impacts on the patients, but there is no definite cure for the disease. The PASI standard is employed to measure the effectiveness of the treatments. It includes four parameters: namely Area, Erythem, Scaliness and skin Thickness. The Area parameter in PASI standard usually is measured by physicians through subjective clinical observations, which are imprecise and boring act and in some cases it leads to diverse results. This paper presents a computer-based semiautomatic method to measure the Area parameter in PASI standard. In the proposed method, the user selects a threshold value for the Cr component in YCbCr color space to differentiate the plaques from the skin. This method has the advantage over the previous methods, that is measuring of plaques with silvery-white and plaques of hairy skins and tiny plaques besides simple plaques (i.e., scale-less plaques).

Part of linear polarized light that illuminates skin is backscattered by the superficial layers and rapidly depolarized by collagen fibers and Particles of light scatterer in skin. It is possible to distinguish such superficially backscattered light from the total reflected light. Method and Material: For this purpose, two images are obtained by a system that includes a linear polarizer in front of the camera (analyzer) and a linear polarizer in front of the light source. First image is Ipar that acquire when the passing axis of analyzer is parallel to the passing axis of polarizer. Second image is Iper that acquire when the passing axis of analyzer is perpendicular to the passing axis of polarizer. Image Pol= (Ipar- Iper)/ (Ipar+ Iper) that is based on the polarization ratio is created. It is shown that we can achieve a lower border error percentage in extracting lesion from dermoscopy images using Pol image. Also qualitative Interpretation of Pol image is useful for assessment of skin lesions and review of treatment process.

Several methods have been introduced for management of periimplantitis. Adjunctive therapies like antibiotics, antiseptics and laser treatments have been proposed in order to improve the non-surgical or surgical treatment options of peri-implantitis. Since lasers have a good capability in ablation of microorganisms and have potent bactericidal and detoxification effects, it has been suggested as one of the best techniques in treatment of periimplantitis. The aim of this study was to review the relevant articles, concerning the application of lasers in treatment of peri-implantitis.Method and Material: PubMed, GoogleScholar, ScienceDirect, InterScience, and IranMedex were searched electronically. The search yielded 44 possibly relevant titles and abstracts. Full texts of 34 English and Persian articles were in access. The results of this article indicated that: (1) In an energy dependent manner, the CO2 laser, the diode laser and the Er:YAG laser may be suitable for the irradiation of implant surfaces. (2) By suppressing LPS activity, low-energy Nd:YAG laser might represent an innovative therapy for periimplantitis. (3) The predominant role of lasers in treatment of peri-implantitis is their bactericidal effects. (4) In non-surgical therapy of contaminated implant surfaces Er:YAG high level lasers have shown limited clinical efficacy. (5) According to the results of animal studies lasers act successfully in the surgical management of peri-implantitis, with regard to re-osseointegration. (6) Photodynamic therapy is a promising method in treatment of peri-implantititis.(7) Laser parameters are determinant factors in effectiveness and safety of treatment. (8) Zirconium implants may react quite differently to lasers. Lasers are utilized as an adjunct in the treatment of periimplantitis. The predominant role of lasers in treatment of peri-implantitis is their bactericidal effects without concomitant titanium surface alterations.

Nitrogen lasers have many applications in medicine nitrogen in these lasers must be have a high purity. Using the air as active laser material is suggestive because nearly 75% nitrogen in air. Possibility of obtaining laser action in the air, because of cheap and availability of air, the air laser will have very application in Iran and the world. In this paper is trying to obtain laser action in the air as experimentally and theoretically. This laser is introduced as Air laser and is suitable for: “treatment of chronic non-responding tubercular lymphadenopathy and sinuses, starting of dye laser for treatment of vascular lesions, Low Level Laser Therapy (LLLT) in Multiple Drug Resistant Pulmonary Tuberculosis, The Biological Effect of Intravenous, Enhances the Biocidal Activity of Human Neutrophils on Internalized Bacteria, Inhibits the Growth of Wide Range of Microbes in Vitro, Treatment of Drug-Resistant Pulmonary Tuberculosis, change Growth of Candida Albicans Apoptosis of Human Polymorphonuclear Cell and Phagocytic Activity of Human Monocytes and etc”. Methods and Materials: In the first step, is stadyed all nitrogen lasers. Then is investigated factors that influence in power output of nitrogen laser. With optimizing of effective parameters, is bilt efficient nitrogen laser. In this step, oxygen is injected to efficient nitrogen laser and is investigated behavior of laser output power. With changing of the effective paremeters in Efficient nitrogen laser, is tried to obtain laser action in high O2 percent in this step, air is injected to Efficient nitrogen laser. With changing of the effective paremeters in air laser, is tried to obtain laser action in every air presseture. With studying of all factors that influence in power output of nitrogen laser and performing them, the pulsed air laser is built which work in air pressure at wavelength 337nm. In this laser, quenching of laser by adding of O2 is investigated and is obtained the turning off pressure as a function of. Also is calculated the case of increasing output power in very low O2 percent. With optimizing of nitrogen laser effective paremeters, the Air laser is bilt that work in air pressesures, less than, equal and large than atmospheric presseture.