فصلنامه لیزر در پزشکی
سال نهم شماره 1 (پیاپی 43، بهار 1391)

Psoriasis is a skin disease which results in red scaly regions in the body. This disease has no well-known definite cure and the proposed medical treatments can only control the disease and reduce its harms. PASI criteria are proposed to measure the effectiveness of the selected treatment on the patients. The PASI criteria consist of four parameters: Area, Erythema, Scaliness and Thickness. The Erythema parameter is usually measured based on subjective methods by the physicians. Subjective measurement of Erythema is time consuming, imprecise and varies if performed by different physicians. Our objective in this research is to propose an automatic objective method to measure Erythema parameter based on image processing techniques. In our research we employed HSV color space because it has the highest correlation with human perception of colors. We specified the correlated component of HSV representation of the psoriasis patients with Erythema parameter. Consequently we used regression modeling to propose a model for automatic measurement of Erythema parameter using HSV color components. We exploited 56 images from psoriasis patients in our research. The results derived from the proposed method for measurement of Erythema parameter were in accordance with the physicians’ diagnosis in 87% of the cases. The proposed method can be used as a tool for automatic measurement of Erythema parameter from digital images captured from psoriasis patients. Moreover, The measurement can be performed without need to any special device.

Rapid and high sensitive detection of biomolecules using optical Surface Enhanced Raman Spectroscopy (SERS) method in the presence gold nanoparticles has been considered for many years. In this paper, microsphere resonator coupled to the optical fiber with the gold nanoparticles based on SERS has been used as ultrahigh sensitive Cardiac Troponin I sensor for trial of myocardial infarction. light from the tunable laser diode (1mW) through the optical fiber coupled to the Microresonator and excite the surface plasmons on the gold nanoparticles surface. Field enhancement of pump due to the Excitation of surface plasmon in λ=545.6 nm, increase Raman signal laser output. The results show the electromagnetic near the gold nanoparticles up to 1012 is enhanced. According to the ultrahigh electromagnetic field, Raman signal is enhanced. The calculated enhanced Raman signal power of laser output depends linearly on the cTnI molecules, resulting cTnI existence around the resonator.

Common wart is a benign proliferation or tumor of mucocutaneous surfaces caused by different types of human papilloma virus (HPV). It is very common in children and young adults.

The aim of this study is to compare therapeutic and side effects of Cryotherapy versus Pulsed Dye Laser (PDL) in the treatment of common warts.

In this prospective controlled randomized clinical trial (RCT), 20 patients with 100 wart lesions were enrolled. The patients were randomly divided into two groups each consisting of 10 patients (with 50 lesions). The treatment protocol for the first group consisted of laser therapy with PDL (wavelength of 585 nm), and the second group treated with Cryotherapy. Patients in both groups were treated every 3 weeks up to 5 times till complete clearance of the lesions achieved. All of the patients were examined in every session of treatments for the clinical response or probable side effects. After completing the proposed course of treatments, patients were examined every 4 weeks for 2 months in order to detect recurrence or probable side effects.

The clinical response for the first group (treated with PDL) and second group (treated with Cryotherapy) were 46.1% and 53.9% respectively. So it was concluded that Cryotherapy has provided better clinical response than PDL, while statistically no meaningful difference between these groups was observed (PV=0.056).

The results of this study showed that laser therapy with PDL in comparison with Cryotherapy leads to less side effects, so the laser therapy could be used as the first line in the treatment of common warts, of course the results of the current study needs to be confirmed.

This investigation has explored the quantum well photodetector responsivity for detecting Surface Enhanced Raman Scattering (SERS) of Troponin enzyme I to be implemented in diagnosing heart attack or myocardial anfractuous.

In this study, we show enhanced transmission in perforated metallic film using Coupled Mode Analytical Method thorough PEC approximation. Implementing the surface impedance boundary condition in the formalism, the effect of surface plasmon polaritons in the transmission spectrum has been analyzed. In addition, we study the effect of a specific substrate on the transmission spectrum. According to a simple model based on multi reflection formalism in Fabry-Perot cavity, it is found that quantum well Al0.45Ga0.55As/AlAs detector responsivity did enhance.

A transmitted light thorough a periodic two dimensional square hole arrays shows anomalous maximum in the transmission spectrum. This phenomenon can be used to enhance electromagnetic field penetration into quantum well layers. It is observed that detector responsivity boosted by introducing perforated metallic films.

A near IR quantum well photodetector is a suitable device for diagnosing diseases thorough transforming optical signals into electrical ones. There is a tradeoff between improvement of detector responsivity for sensing Troponin I and efficiency of detector.

As a person ages, the adult teeth often become darker due to changes in the mineral structure of the tooth, as the enamel becomes less porous. Teeth can also become stained by bacterial pigments, foodstuffs and tobacco. Dental bleaching was introduced in dentistry in 1877. However, due to modern standards of beauty, this treatment modality has been in great demand and has been the subject of various scientific researches. Therefore, this procedure has undergone many changes. Nevertheless, the action mechanism remains the same, consisting of an oxide reduction reaction with release of active oxygen, free radicals in a solvent (especially water) in which the substance to be bleached donates electrons to the bleaching agent, normally hydrogen peroxide. Due to its low molecular weight, the bleaching agent penetrates through the porosities of the enamel prisms, reaches the dentin, comes into contact with a large quantity of pigmented organic molecules and breaks them up into shorter and lighter chains that allow the absorption of light in shorter wavelengths. To accelerate this process of oxidation, various sources of energy can be used, such as heat and light. Bleaching corrects or improves the color of teeth, and is also the least expensive esthetic treatment option. The indications are acquired superficial stains, penetration and absorbed stains, age-related stains, patients who desire conservative treatment to improve appearance, color change related to pulp trauma and necrosis, and interproximal discolorations. A search was performed using the keywords "tooth bleaching" and "laser" to identify the current literature on the Tooth bleaching with laser. The related articles were searched in databases including IDL, Pub med, Google scholar, and Medline from 2004 to 2010. It is found that selective diode laser radiation can decrease the time of bleaching without surface modification. No differences between enamel surfaces were observed. Currently, the laser has been proven to be the most valuable energy source for power bleaching with simple and short application in the office.