Lasers in Medicine
Year:2011 | Volume:8 | Issue:3 (41)|Papers Count:6

Background: Melanoma is a dangerous skin cancer that early diagnosis is the treatment key. Dermatoscopy as the commonest approach to assess pigmented and non-pigmented skin lesions noninvasively based on visual inspections. In addition, this technique is not capable to provide precise cancer stage estimation.Material and Methods: Polarization characterization of skin lesions through Mueller matrix images or stokes images is suggested as a complementary methodology for dermatoscopy to help in extraction more quantitative and qualitative information.Results: Using polarized light in imaging increases contrast, so that discriminative features of pigmented lesions. Become more highlighted different stages of being cancerous in pigmented lesions, occur with changes in sizes shape, collagen fiber structure and accumulation of melanocytes. Interaction of skin-polarized light can be applied for differentiating cancerous and noncancerous lesions because of these morphological variations.Conclusion: By monitoring the changes based on polarization characteristics of tissues, it is possible to access more information regarding tension physiology and cancer stage.

Background: Nowadays cancer detection in preliminary stages is one of the most important problems for physicians. One of the new imaging techniques, which have special capability in the detection of small size lesions, is optoacoustic imaging. In this paper have introduced this technique and have simulated optoacoustic wave generation in spherical tumors of breast.Material and Methods: In this research for the generation of acoustic pressure as a result of laser energy reception in an absorbing sphere, a transfer functions in backward mode has been introduced. Then using this model effect of changes in laser pulse width, dimensions and depth of tumor and absorption coefficient of tumor and media on properties of generated ultrasound have been surveyed. All of simulations have been accomplished in MATLAB7 software platform.Results: investigation of pulse width effect on generated optoacoustic wave illustrated that increase of laser pulse duration causes to increase in ultrasound amplitude. Investigation of tumor absorption coefficient as a function of tumor type showed that Increase of absorption coefficient of tumor causes to increase in ultrasound amplitude, but more increase in absorption coefficient causes to saturation in ultrasound amplitude and in high absorption coefficient relation between generated ultrasound amplitude and absorption coefficient because of order two.Conclusion: For designing a laser- ultrasound system with maximum efficiency, we can choose optimum system using this model and simulation results with testing of various parameters of available laser systems. In addition, we can use obtained results for tumor specification in clinical applications of this technique.

Background: Quantitative assessment of pigments’ aggregation in skin lesions helps accurate diagnosis. This is also instrumental in monitoring the process of treatment especially when lasers are used to treat skin lesions. Spectroscopy has provided necessary instrumentations for quantitative evaluation of skin pigmentation. Having a broad wavelength range, ease of use and quickness are some advantages of spectroscopy. On the other hand, due to the overlapping of pigments’ absorption spectra, separation of pigments’ intensities is not a straightforward issue and requires scientific methods.Material and Methods: In this study, the spectrum of human skin has been achieved for 5 different parts of 10 volunteers’ skin. The volunteers were 24-28 years old from both genders. The achieved spectrum was fitted according to absorption Gaussian peaks of pigments using Qtiplot software package and the intensity of each sub-peak was calculated. Two comparisons were performed in order to assess accuracy of the experiment. In the first comparison which shows accuracy of the experimental method, the redness and the blood concentration of different parts of skin were evaluated. In the second comparison, the accuracy of fitting process was tested. To do so, the ratio of di-oxi homoglobin to oxy hemoglobin in volunteers’ lips was compared. This ratio represents how bright the person’ lips might be.Results: In this paper, we have presented a method for quantifing the amount of pigments in absorption spectrum of human skin. This was done by fitting the spectrum according to absorption peaks of pigments. The excellent correlation coefficient between the experimental spectrum and fitted curve shows a good precision. Two comparisions were performed in order to test the accuracy and precision of this method. Both comparisons confirmed the viability of the method.Conclusion: With this method, the changes in skin pigmentation caused by disease can be expressed quantitively.

Background: Chemo mechanical debridement is an important part of endodontic treatment. Elimination of pulpal tissue, microbiota and their by-products, organic and inorganic debris removal by using instruments and intracanal irrigants are objectives of this important phase of treatment. The aim of this study was to ex-vivo evaluation of smear layer removal in conventional clinical methods, Passive Ultrasonic Irrigation, Laser Activated Irrigation.Material and Methods: 54 anterior mandibular teeth was used in this study. After preparation of samples, they were divided in to 3 groups of Conventional Irrigation +Smear layer removal, Passive Ultrasonic Irrigation, Laser Activated Irrigation. Then, the samples were cut longitudinally in mesiodistal direction for examination by SEM (1500X) for assessing smear layer removal.Results: In coronal, middle and apical one third, the best result was obtained from Conventional Irrigation + Smear layer removal group for smear layer removal.Conclusion: According to better smear layer removal in Conventional Irrigation + Smear layer, it is considered as gold standard protocol and other groups cannot be a suitable substitution for this method.

Background: Interaction of laser and vital tissue is one of the most interesting subjects in low level laser therapy (LLLT) for therapeutic applications. Many of in-vitro studies have done to clarify the laser mechanisms for accelerating the wound healing process.The most important suggested mechanisms include: alleviation of inflammation and acceleration of proliferation phases, anti-bacterial effect, promotion in mitochondrial signaling, promotion of vascularization, and change the injury potential that all of them can accelerate wound closure consequently. In this study, we tried to review the most important mechanisms of LLLT suggested in related studies.