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Laser-Tissue Interactions. Niemz Subscribe to alerts Get information about new releases for these contributors straight to your inbox. Markolf H. Be the first to write a review. This item qualifies for FREE delivery. Buy Now. Arrives at our Sydney warehouse in weeks and once received will be despatched with online tracking. Please allow additional time for delivery to your address. See the Delivery tab below for more details. Synopsis Product Details Delivery "Laser-Tissue Interactions" provides a thorough description of the fundamentals and applications in this field.

Basic concepts such as the optical and thermal properties of tissue, the various types of tissue ablation, and optical breakdown and its related effects are treated in detail. Special attention is given to mathematical tools Monte Carlo simulations, the Kubelka-Munk theory etc. The part on applications reviews clinically relevant methods in modern medicine using the latest references. The last chapter covers today's standards of laser safety, with a careful selection of essential guidelines published by the Laser Institute of America.

Numerous research photographs, illustrations, tables and comprehensive summaries make this book a useful guide for graduate students, scientists, and medical practitioners. New end-of-chapter exercises provide readers with the opportunity to check their understanding of key concepts and techniques. Let's Try No, Thanks. Select the List you'd like to categorise as, or add your own.

Laser-Tissue Interactions: Fundamentals and Applications / Edition 3

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Newsletter Be the first to know, sign up for our newsletter:. Payment methods: Proudly secured by:. Copyright All rights reserved. Please sign in to continue. Continue with Facebook Continue with Twitter. Don't have an account? Create an account. When laser light strikes a tissue surface, it can be reflected and refracted, scattered, absorbed or transmitted Das, In medical laser applications, refraction plays a significant role when irradiating transparent media like corneal tissue.

In opaque media, usually, the effect of refraction is difficult to measure due to the absorption and scattering Niemz, Laser light passing through the tissue undergoes multiple scattering processes and is transformed from a narrow collimated beam into a broad diffuse beam Mosaad, Scattering coefficient increases with the increase of the wavelength, thus, UV light is scattered more than IR light Niemz, All the effects of light begin with the absorption of electromagnetic radiation Elliott, During absorption, the intensity of an incident light is attenuated by passing through a medium due to a partial conversion of light energy into heat motion or certain vibrations of molecules of the absorbing material.

The ability of a medium to absorb electromagnetic radiation depends on a number of factors, mainly the electronic constitution of its atoms and molecules, the wavelength of radiation, the thickness of the absorbing layer and internal parameters such as temperature or concentration; Fig. Two laws are frequently applied; they describe the effect of either the thickness or concentration on absorption, respectively.

The most important optical property that decides the suitability of a laser for a surgical procedure is the penetration depth of its radiation in the tissue. The penetration depth changes significantly with the wavelength of the laser radiation Julia et al. In the red portion of the spectrum and in near infrared region, the penetration depth can be considerably greater.

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In spectral regions where the absorption coefficient is relatively high, such as at In biological tissue, either water molecules or macromolecules such as proteins and pigments mainly cause absorption. The absorption of infrared light can be attributed to water molecules, whereas UV and visible light absorbs by proteins and pigments Julia et al. It can produce fluorescence and this is used in dentistry in diagnosis of initial dental carries that based on spot emission fluorescence Julia et al.

The variety of interaction mechanisms may occur when applying laser light to biological tissue due to specific tissue characteristics as well as laser parameters Julia et al. Wavelength dependent mechanisms Photothermal interaction mechanisms: The most frequently used mechanism of photon energy conversion in laser medicine is heating. Heating of irradiated sample occurs with all methods of tissue destruction coagulation, vaporization, cutting, etc. Karu, Photons absorbed by the tissue are thought to cause biological effect via nonspecific Photothermal effects caused by kinetic mechanism, the external energy from the laser photons is deposited into the target materials via transitional, rotational and vibrational modes of movements of the target molecules.

The rotational and vibrational modes of movement which are in fact criteria of the temperature or Kinetic Energy KE of the target molecules. The extracted energy from the incident light most efficient when the frequency of the incident photons is close to the characteristic frequencies of these modes resonance absorption Bedrym, ; Fitzpatrick and Goldman, When laser energy is converted into heat in the tissue, thermal diffusion begins.

Diffusion of heat through the tissue depends on the thermal properties of the irradiated material. The thermal relaxation cooling phenomenon is influenced by the thermal coefficient of the tissue, the properties of the surrounding tissue or fluids and the temperature differential between the irradiated and non irradiated tissue Litvack et al. However, depending on the duration and peak value of the tissue temperature achieved, different effects like coagulation, carbonization, vaporization and melting may be distinguished.

For thermal decomposition of tissues, it is important to adjust the duration of the laser pulse in order to minimize thermal damage to adjacent structures. The microscopical and bio chemical analysis showed that as the temperature is raised, the large, specially configured molecules necessary for life are shaken open. The most important and significant tissue alterations are dependent on the temperature of the tissue after absorption of the laser radiation, as follows:.

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Thermal effects of laser radiation are listed in Table 1. The group of photochemical interaction mechanisms stems from empirical observations that light can induce chemical effects and reactions within macromolecules or tissues. Photochemical effects occur as a result of direct excitation of electronic bonds by the laser energy Litvack et al.

In general most of the molecules of the tissue have their bonding in the ultraviolet frequency region Bedrym, At shorter wavelengths, tissue components become electronically excited, thus, this photo excitation leads to rupture of molecular bonds and formation of molecular fragments Litvack et al. Photochemical reactions generally do not result in a significant rise in temperature. Photochemical effects involved either a change in the course of biochemical reaction due to the presence of an electromagnetic field or photodecomposition due to high energy photons that rupture molecular bonds Das, ; Monajembashi et al.

Photochemical interaction mechanisms take place at very low power densities typically 1 W cm -2 and long exposure times ranging from seconds to CW lasers. In most cases, wavelengths in the visible range are used because of their high optical penetration depths.


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Several applications of the photochemical interaction mechanisms have been used as in the following sections Niemz, Photodynamic Therapy: The photodynamic therapy reaction is mediated by exogenous chromospheres. At low light intensities, laser energy is absorbed by exogenous chromospheres molecules called photosensitizes photo acceptors. In this case, the light is used for activation of molecules or drugs by a specific wavelength of the laser light. The absorbing molecule can transfer the energy to another molecule and this activated molecule can then cause chemical reactions in the surrounding tissue.

The molecule may be transformed into toxic compound, often involving oxygen-free radical that can cause cellular death through destruction of the DNA molecule Niemz, ; Khosravi et al. This type of reaction is successfully used in the Photodynamic Therapy PDT of tumor; where the photoabsorbing molecules are artificially introduced into a tissue before irradiation.

Irradiation of cells at certain wavelength can also activate some of the native components Sisecioglu et al.

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In this way specific biochemical reactions as well as whole cellular metabolism can be altered. This type of reaction is believed to form the basis for low power laser effect. Biostimulation using light energy which is usually considered a photochcmical effect, is a procedure that has attracted interest in both the clinical and research arenas in both human medicine and veterinary. To many scientists and clinicians, the idea is that low intensity light energy can promote and upgrade metabolic processes that result in tissue repair and pain relief which is unbelievable.

Also in the area of injuries, conditions are usually created preventing proliferation such as low oxygen concentration or pH. The exposure to red or near infrared light might thus serve as a stimulus to increase cell proliferation Niemz, Reports from almost every region of the world indicate that low intensity lasers promote the repair process of skin, tendons, ligaments, bone and cartilage in experimental animals as well as wounds from various etiologies in humans Weesner, Photoablation therapy: Photoablation was first discovered by Srinivasan and Mayne-Banton in the year They identified it as ablative photodecomposition, meaning that material is decomposed when exposed to high intense laser irradiation.

It occurs when the energetic photons of the laser light decomposes the molecules by breaking the chemical bonds. In this interaction, photoablation is due to the "volume stress" as a result of bond breaking. The removal of tissue is performed in a very clean and exact fashion without any appearance of thermal damage such as coagulation or vaporization. Photoablation takes place in the intensity range of 10 4 10 W cm -2 and interaction time in the range of 10 -3 sec.

But the typical threshold values of this type of interaction are 10 7 8 W cm -2 at laser pulse durations in the nanosecond range. The main advantages of this ablation technique lie in the precision of the dental enamel etching process and the lack of thermal damage to adjacent tissues Niemz, Currently, most of the ablation work is done with UV excimer laser Beesly, ; Karu, When the energetic photons of the laser light decompose the molecules by breaking the bonds at the impart excess energy for ejection Weesner, ; Hemachandran and Arumugam, Interaction of light with biological tissue is seen in Fig.

Wavelength independent mechanisms: When using power densities exceeding 10 11 W cm -2 in solids and fluids or 10 14 W cm -2 in air, where the pulse duration is in picosecond or femtosecond range, multiphoton ionization of atoms and molecules may occur a phenomenon called optical breakdown occurs. The physical effects associated with optical breakdown are plasma formation and shock wave generation.

If breakdown occurs inside soft tissues or fluids, cavitations and jet formation may additionally take place. By means of plasma-induced ablation, very clean and well defined removal of tissue without evidence of thermal or mechanical damage can be achieved when choosing appropriate laser parameters Gordon, as shown in Fig.

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Uncontrolled, the effect of the plasma on the tissue surface can cause tissue damage Featherstone and Neslon, The ultra short laser pulses with pulse durations shorter than ps-each of them having no thermal effect-may add up to a measurable increase in temperature if it applied at repetition rates higher than about Hz, depending on the laser. The most important parameter of plasma-induced ablation is the local electric field E which determines when optical breakdown is achieved.

If E exceeds a certain threshold value as in mode locked lasers, where the pulse duration is in picosecond or femtosecond range, multiphoton ionization of atoms and molecules may occur, optical breakdown is achieved Wintner, ; Stern, The important feature of optical breakdown is that it renders possible an energy deposition not only in pigmented tissue but also in nominally weakly absorbing media.

This means that the interaction does not depend on the wavelength Wintner, During photo disruption, the tissue is split by mechanical forces. Whereas plasma-induced ablation is spatially confined to the breakdown region. For nanosecond pulses optical breakdown is always associated with shock wave formation even at the very high threshold. Since adjacent tissue can be damaged by disruptive forces, the presence of these effects is often an undesired but associated symptom Wintner, Picosecond or femtosecond pulses permit the generation of high peak intensities with considerably lower pulse energies.

With these extremely short pulse durations, optical breakdown may still be achieved while significantly reducing plasma energy and, thus, disruptive effects Wintner, The important feature of optical breakdown is that it renders possible an energy deposition not only in pigmented tissue but also in nominally weakly absorbing media, This means that the interaction does not depend on the wavelength Stern, Since adjacent tissue can be damaged by disruptive forces, the presence of these effects is often an undesired but associated symptom Stern, Laser hazards effects: Laser radiation hazards must be identified and evaluated.

Types of laser hazards:. Inhaled airborne contaminants can be emitted in the form of smoke or plume that generated through thermal interaction of surgical lasers with tissue Miserendino and Pick, ; Sisecioglu et al. Laser plume evacuated device is used, to eliminate laser plume or smoke which is irritant to the pulmonary tree because it is carrying particles of tissue and microorganism. In addition, masks are necessary to use by the medical staff.

They act as filters to protect the pulmonary system from the possibilities of an infection by microorganism. Muncheryan, ; Al-Alawi, Laser and laser systems are grouped according to their capacity to produce injury and specific controls are then described for each group.