Laser Applications In Medicine Research Articles

Determination of microscopic optical properties of agar and Zerdine phantoms at 635 nm using Kubelka-Munk function approach: A numerical study

<p><span>Since the precise and accurate determination of the optical properties of materials is very important for the development and application of optical technology, the investigation of the optical properties of biological tissues with tissue-like phantoms is an important research field in the applications of lasers in medicine. In this study, after directly determining the macroscopic optical properties of the agar and Zerdine phantoms at 635 nm, including the absorbance, transmittance, reflectance, refractive index, and total attenuation coefficient with the single integrating sphere test apparatus; the microscopic optical characterization of these two different soft tissue phantoms were realized at 635 nm by using the Kubelka-Munk function approach. For this, the microscopic optical parameters, which are the absorption coefficient, scattering coefficient, reduced scattering coefficient, and penetration depth, were calculated over these determined macroscopic optical properties.</span></p>

Assessment of Dysregulation of HERC6 and Essential Biological Processes in Response to Laser Therapy of Human Arm Skin.

Introduction: The widespread application of lasers in medicine, especially in the treatment of diseases implies more investigations to understand the precious molecular mechanism of the laser effect on the human body. In the present study, the prominent role of HERC6 in response to CO2 Laser therapy of human skin is investigated. Methods: The numbers of 16 gene expression profiles before and after the treatment with the CO2 laser are downloaded from Gene Expression Omnibus (GEO), and differentially-expressed genes (DEGs) are analyzed to find the significant DEGs. Gene ontology analysis revealed that HERC6 and a set of its neighbors played a significant role in response to laser application. Results: The expression changes of 52 significant DEGs were compared via heat map analysis and 27 significant DEGs were introduced as the critical genes which are involved in response to laser irradiation. "Thymidylate kinase activity" among 9 clusters of biological terms was highlighted as an important biological process related to the identified DEGs. HERC2 was proposed as a critical DEG which was related to several essential cellular processes in response to laser application. Conclusion: The findings from the present study indicate that HERC6 and the numbers of its first neighbors are involved in the essential cellular response to laser therapy of human skin.

Laser radiation. Main directions of using in biology and medicine. Prospects for development

The article considers modern ways of diagnostic and clinical application of lasers in medicine. Laser technologies in biology, medicine are analyzed. A set of methods of laser therapy, which form a new direction - optical coherent medicine, is given.

Light and energy based therapeutics for genitourinary syndrome of menopause: Consensus and controversies.

Gynecologist and plastic surgeons pioneered the application of lasers in medicine and surgery almost 5 decades ago, initially used to treat cervical and vaginal pathologies. Ever since, energy-based devices have been deployed to treat pelvic pathologies and improve fertility. Recent technological developments triggered an unprecedented wave of publications, assessing the efficacy of fractional laser, and radiofrequency on the vaginal wall in reversing natural aging processes. Studies have shown that a certain degree of thermal energy deposited on the vaginal wall stimulates proliferation of the glycogen-enriched epithelium, neovascularization, and collagen formation in the lamina propria, and improves natural lubrication and control of urination. This review aimed to review such data and to guide future research. A unique assembly of experts from around the globe, compiled and edited this manuscript based on a thorough literature review and personal experience. Lasers Surg. Med. 49:137-159, 2017. © 2017 Wiley Periodicals, Inc.

Metal nanoparticles and IR laser applications in medicine for biotissue ablation and welding

We report the possibility of laser welding and ablation of biotissue by using metal and hybrid metal nanoparticles (NPs) and infrared laser irradiation spectrally located far from plasmon resonances. A nanosecond YAG:Nd laser of wavelength 1064 nm has been used for synthesis of metal NPs. The Ag, Au, Cu, Ti and Ni, as well as Au–Ag and Au–Cu hybrid metal colloidal NPs were formed in a liquid medium. The diagnostic technique of second harmonic generation (SHG) has been applied to determine the biotissue ablation area after IR laser irradiation. The effectiveness of biotissue ablation was 4–5 times larger in the case of a tissue sample colored with metal NPs than for an uncolored sample. IR laser welding has been demonstrated for deep-located biotissue layers colored by metal NPs.

A prediction model for ocular damage – Experimental validation

With the increasing number of laser applications in medicine and technology, accidental as well as intentional exposure of the human eye to laser sources has become a major concern. Therefore, a prediction model for ocular damage (PMOD) is presented within this work and validated for long-term exposure. This model is a combination of a raytracing model with a thermodynamical model of the human and an application which determines the thermal damage by the implementation of the Arrhenius integral. The model is based on our earlier work and is here validated against temperature measurements taken with porcine eye samples. For this validation, three different powers were used: 50mW, 100mW and 200mW with a spot size of 1.9mm. Also, the measurements were taken with two different sensing systems, an infrared camera and a fibre optic probe placed within the tissue. The temperatures were measured up to 60s and then compared against simulations. The measured temperatures were found to be in good agreement with the values predicted by the PMOD-model. To our best knowledge, this is the first model which is validated for both short-term and long-term irradiations in terms of temperature and thus demonstrates that temperatures can be accurately predicted within the thermal damage regime.

Hybrid optoacoustic and ultrasound biomicroscopy monitors’ laser-induced tissue modifications and magnetite nanoparticle impregnation

Tissue modification under laser radiation is emerging as one of the advanced applications of lasers in medicine, with treatments ranging from reshaping and regeneration of cartilage to normalization of the intraocular pressure. Laser-induced structural alterations can be studied using conventional microscopic techniques applied to thin specimen. Yet, development of non-invasive imaging methods for deep tissue monitoring of structural alterations under laser radiation is of great importance, especially for attaining efficient feedback during the procedures. We developed a fast scanning biomicroscopy system that can simultaneously deliver both optoacoustic and pulse-echo ultrasound contrast from intact tissues and show that both modalities allow manifesting the laser-induced changes in cartilage and sclera. Furthermore, images of the sclera samples reveal a crater developing around the center of the laser-irradiated spot as well as a certain degree of thickening within the treated zone, presumably due to pore formation. Finally, we were able to observe selective impregnation of magnetite nanoparticles into the cartilage, thus demonstrating a possible contrast enhancement approach for studying specific treatment effects. Overall, the new imaging approach holds promise for development of noninvasive feedback control systems that could guarantee efficacy and safety of laser-based medical procedures.

Optical Devices in Ophthalmology and Optometry: Technology, Design Principles and Clinical Applications

Optical Devices in Ophthalmology and Optometry is a highly recommended textbook that explains the physical principles of optics, photonics, metrology, and lasers, and proceeds with the design principles and instrument construction of medical devices that are most often used in diagnosis and treatment. The textbook is based on the lectures that two of the authors taught to graduate students with backgrounds in physics, electrical, and mechanical engineering. The author’s aim in their courses is to bridge the physics and engineering with the development of medical devices for ophthalmology and optometry. But this textbook’s intended audience consists of engineers and physicists who work in academic or industrial research. Together the authors built upon their expertise in optics, medical technology, laser development and laser applications in medicine, and medical devices to produce a comprehensive textbook that is physically rigorous, clearly written, well illustrated with clear, colored figures, and enhanced by extensive footnotes, problem sets, critical references, a summary of all the used mathematical variables and abbreviations, and an index.

History of the World Federation of Societies for Laser Medicine and Surgery (WFSLMS) and its Non-Profit Organization (NPO-WFSLMS): Part 1: Origins to Inaugural Meeting, 2005.

The first society formed to represent the "new" field of laser applications in medicine and surgery was the late Professor Kaplan's International Society for Laser Surgery and Medicine, held in Israel in 1975. Following the ISLSM lead, a large number of national and international societies were very swiftly formed. As the number grew, it became obvious that some sort of linking forum would help all these separate societies to pool the knowledge of their members for the good of the clinicians and their patients. The World Federation of Societies for Laser Medicine and Surgery was formed to attempt to fill this role. The History: At the 1996 meeting of the Greek Medical Laser Association, the first international forum of representatives from 17 international and national laser societies was convened by Professor Nick Nicolopoulos, and the seed of an idea for a centralized forum to help separate laser societies coordinate efforts and knowledge was planted. This seed was nurtured by the ISLSM as the first medical laser society, and forums were called together at each meeting of the ISLSM and the other related societies from 1997 to 2003. At the 2004 Chinese Medical Laser Society meeting, the idea of worldwide federation of laser societies crystallized into a more tangible form The Inaugural WFSLMS Congress: The convening of the first WFSLMS congress took place in Tokyo in 2005, under the leadership of Professor Kazuhiko Atsumi. At this meeting, Professor Kaplan proposed that a Medical Laser Foundation should be established and donated the first seed money for its formation. Because of the Japanese legal requirements, a foundation was impossible and so a Non-profit Organization (NPO-WFSLMS) was started, based in Japan, to oversee the work and fund the tasks of promoting laser surgery and medicine worldwide, for the good of mankind: the financing, running and holding WFSLMS congresses became one of the tasks of NPO-WFSLMS. Both the WFSLMS and NPO-WFSLMS were therefore on their way to working together for a cohesive approach to try and coordinate the work of all societies dedicated to laser medicine and surgery under the WFSLMS umbrella, with NPO-WFSLMS continuously gathering, administering and disbursing the funds to allow the WFSLMS to run its 4-yearly meetings.

Computational Research of Internal Temperature Distribution for Liver Tissues under Laser Irradiation

To study the effect of blood perfusion rate and air convection boundary condition upon heat transfer of liver tissues by establishing heat conduction model of liver tissues under laser irradiation.The analytical solution of the model was solved by homogenizing boundary condition and the numerical solution of the bio-heat transfer model under the two-dimensional cylindrical coordinate was calculated by the Finite Element Method (FEM).The results show that the highest temperature irradiated by laser is on the center point of the surface tissue, and decreases in the radial and axial direction, the temperature in the axial degrades more seriously than that in the radial.This study provides a theoretic bases for laser applications in medicine.

Optical properties of normal and thermally coagulated chicken liver tissue measured ex-vivo with diffuse reflectance

The purpose of the present study is to determine the optical properties of normal and thermally coagulated chicken liver at 720, 740, 770, 810, 825 and 840 nm wavelengths of laser irradiation. So, we were able to evaluate these optical properties (absorption and scattering coefficients) with ex-vivo study using Kubelka Munk Model (KMM) from the radial dependence of the diffuse reflectance with femtosecond pulsed laser in near IR region. These coefficients were significantly increased with coagulation. The penetration depths of the diffused light have been reported to a maximum value of 8.12 ± 0.36 mm in normal liver and 2.49 ± 0.17 mm in coagulated liver at 840 nm showing increasing behavior towards IR region. The Monte Carlo simulation was used to check the theoretical validation of measured optical properties of the tissue that showed a good match with our experimental results. We believe that these differences in optical properties will be helpful for the understanding arid optimal use of laser applications in medicine and differential diagnosis of tissues by using different optical methods. Especially for the investigation of biological tissue for photodynamic therapy (PDT), the knowledge of the specific optical properties and their thermo-induced changes is important.

Medical applications of mid-IR lasers Problems and prospects

Any application of lasers in medicine is based on a compromise between the efficiency with which the laser radiation interacts with biological tissue and the concomitant collateral effects. Correspondingly, parameters minimizing undesirable damage to tissue must be determined. The development of a new generation of solid-state lasers tunable over a wide range in the mid-IR range of the spectrum with parametric generation of light and a combination of high radiation intensity and relatively low pulse energy at high repetition frequency opens up new possibilities for less-invasive, high-precision, laser surgery, first and foremost, in ophthamology and neuro- and cardiosurgery.

Theoretical investigations of the processes of selective laser interaction with melanin granules in pigmented tissues for laser applications in medicine

Theoretical investigations and the results of computer modeling of optical, thermophysical, thermochemical, and hydrodynamical processes during selective laser interaction with melanoprotein granules (melanosomes) in heterogeneous pigmented tissues (retinal pigment epithelium) are reviewed in this paper. Physico-mathematical models and system of equations are formulated which describe interaction processes for “short” laser pulses of duration t p < 10−6 s and for “long” pulses of duration t p > 10−6 s. The results of numerical simulation of the processes give the space-time distributions of temperature and degrees of thermodenaturation of the protein molecules inside and around melanosomes and in the volume of irradiated tissue. Energy absorption, heat transfer, and thermochemical processes occurring during the interaction of laser pulses with pigmented spherical and spheroidal granules in heterogeneous tissues are theoretically investigated. The possibility for selective interaction of short laser pulses with pigmented granules, which results in the formation of denaturation microregions inside and near the pigmented granules (granular thermodenaturation) without origination of a continuous macroscopic thermodenaturation lesion in tissue, is discussed. An analytical model of heating of a single spherical and spheroidal granule by a laser pulse is presented. Simple equations for the time dependences of particle temperature are obtained. Vapor generation under the action of a laser pulse on pigmented spherical granules in a water-containing tissue and the formation and dynamics of a vapor blanket are theoretically investigated. The values of pulse energy which give rise to granular and ophthalmoscopically visible thermodenaturation lesions on the retina and to vapor generation are discussed, as well as laser-induced breakdown on granules in pigmented tissues, on the basis of experimental results and numerical and analytical calculations. The comparison and agreement of the numerical results with the experimental data validate the models and techniques developed. The presented results are of essential interest for laser applications in ophthalmology and can be used to investigate laser interaction with heterogeneous tissues in dermatology and various fields of laser medicine.

Enhancement of transepidermal skin clearing agent delivery using a 980 nm diode laser

Patient compliant optical skin clearing requires non-invasive topical delivery of clearing agents such as glycerol. This requires reducing the skin barrier function by disrupting stratum corneum integrity, which was achieved using a 980 nm diode laser with artificial absorption substrates on the skin surface. Reduction of light scattering has the potential to improve many current and novel diagnostic and therapeutic applications of lasers in medicine. In vivo hamster and rat skin was used to test optical skin clearing. Absorption substrates were applied to the skin after shaving. These included black ink, dark children's rub-on tattoo, and carbon paper. 980 nm cw laser light was used to ablate these substrates and to heat the skin surface to enhance the diffusion of topically applied glycerol for optical skin clearing. Increased light penetration was determined from amplitude optical coherence tomography data. Results indicate an improvement of the ability to measure an OCT signal at a wavelength of 1,290 nm up to 42% deeper into in vivo rodent skin using a 980 nm laser with a fluence of less than 0.96 J/mm(2) to alter the stratum corneum. The use of an inexpensive diode laser can significantly enhance the delivery of topically applied glycerol for optical skin clearing. The laser use involves application of an absorption substrate onto the skin surface. Using carbon paper left no unwanted residue behind and is considered optimal for this purpose.

Numerical Study on the Thawing Process of Biological Tissue Induced by Laser Irradiation

Most of the laser applications in medicine and biology involve thermal effects. The laser-tissue thermal interaction has therefore received more and more attentions in recent years. However, previous works were mainly focused on the case of laser heating on normal tissues (37 degrees C or above). To date, little is known on the mechanisms of laser heating on the frozen biological tissues. Several latest experimental investigations have demonstrated that lasers have great potentials in tissue cryopreservation. But the lack of theoretical interpretation limits its further application in this area. The present paper proposes a numerical model for the thawing of biological tissues caused by laser irradiation. The Monte Carlo approach and the effective heat capacity method are, respectively, employed to simulate the light propagation and solid-liquid phase change heat transfer. The proposed model has four important features: (1) the tissue is considered as a nonideal material, in which phase transition occurs over a wide temperature range; (2) the solid phase, transition phase, and the liquid phase have different thermophysical properties; (3) the variations in optical properties due to phase-change are also taken into consideration; and (4) the light distribution is changing continually with the advancement of the thawing fronts. To this end, 15 thawing-front geometric configurations are presented for the Monte Carlo simulation. The least-squares parabola fitting technique is applied to approximate the shape of the thawing front. And then, a detailed algorithm of calculating the photon reflection/refraction behaviors at the thawing front is described. Finally, we develop a coupled light/heat transport solution procedure for the laser-induced thawing of frozen tissues. The proposed model is compared with three test problems and good agreement is obtained. The calculated results show that the light reflectance/transmittance at the tissue surface are continually changing with the progression of the thawing fronts and that lasers provide a new heating method superior to conventional heating through surface conduction because it can achieve a uniform volumetric heating. Parametric studies are performed to test the influences of the optical properties of tissue on the thawing process. The proposed model is rather general in nature and therefore can be applied to other nonbiological problems as long as the materials are absorbing and scattering media.

Effects of dehydration on the optical properties of in vitro porcine liver.

It is of crucial importance to determine the effects of dehydration on the optical properties of tissue so that optimization of therapy and device for laser applications in medicine can be made. After being incubated directly or indirectly in an oven of 37 degrees C for different periods of time, the porcine liver samples were weighed with an electronic scale and their optical properties were measured by a double integrating sphere system. When samples were incubated directly for 20 hours, the average weight loss was 68.5% +/- 1.2%, and the absorption coefficient and scattering coefficient increased 146.1% +/- 26.9% and 10.8% +/- 1.1%, respectively. In comparison, there was only 21.5% +/- 1.0% of water loss for the control samples, and the absorption coefficient increased 30.7% +/- 7.6%, while the reduced scattering coefficient increased 386.5% +/- 29.7%. The effective attenuation coefficients increased 111% and 103% for dehydration group and control group, respectively. The absorption coefficient and effective attenuation coefficient increase with dehydration level of tissue. However, there is no direct correlation between dehydration and reduced scattering coefficient.

Notes on Past and Current Research at the Laser Centre in Amsterdam

Summary Since the foundation of the Laser Centre of the Academic Medical Centre in Amsterdam in 1987, multidisciplinary teams of medical doctors and physicists and sometimes specialists from other disciplines such as mathematicians, biologists, dentists and chemists have worked on a variety of topics. Their work has been (and is) focussed on both diagnostic and therapeutic laser applications in medicine and examples of past and present work are given with emphasis on photodynamic therapy and fluorescence spectroscopy, optical coherence tomography and transmyocardial laser revascularisation.

Application of lasers in medicine

Application of lasers in medicine

Mid–infrared laser applications in medicine and biology

The midinfrared (midIR) should be a fruitful area for medical research and instrumentation since this is the region where the most identifiable molecular molecules absorb and radiate. Due to the un...

Formation of volatile organic compounds from peptides during CO2-IR-laser irradiation of different mammalian tissues

Applications of lasers in medicine for diagnostical and surgical purposes were spreading in the last decade. Surgical use of medical lasers can cause pyrolysis products as gases, vapours and fine particles or aerosols evaporating from the surgical theatre. Risk assessment to humans exposed to these potentially toxic agents needs a comprehensive analytical approach for characterizing these complex mixtures. In the respirable volatile organic compounds (VOC) fraction of laser treated model organs, besides a wide range of pyrolytic fragmentation and Maillard reaction products, two new classes of compounds, 2,4 dialkyl-2H-pyrrole 3,5 (3H) diones and 3-alkenyl-5-alkyl-pyrrolidine 2,4 diones, could be detected. According to our present knowledge, about 35 possible compounds belong to two families of alkylalkenyl substituted diketopyrrolidines and dialkyl substituted diketopyrrolines (DKP). Formation of these compounds was first detected by Curie-point pyrolysis of protein-containing organic matter. Special sources of these VOC may be paired aliphatic amino acids in peptides. Laser-tissue interaction along with (poly-)amino acids with alkyl substituents will be a favourable source of these new volatile organics.