DOCSLIB.ORG

Ocular Hazards of the Q-Switched Erbium Laser

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Ocular Hazards of the Q-Switched Erbium Laser Ocular hazards of the Q-switched erbium laser David J. Lund, Maurice B. Landers, George H. Bresnick, James O. Powell, Jack E. Chester, and Charles Carver The threshold for ocular damage was determined in owl monkeys with the use of a Q-switched erbium-glass laser at 1.54/J. constructed in the laboratory. Ocular damage was limited to the cornea and characterized by localized opacification of the epithelium and stroma. All exposures to energy densities greater than 30 j./cm.2 produced injury. The median level for damage occurred at 21 j./cm.2, and no injury could be detected below 17 j./cm.2. Comparison with threshold values for ocular damage by Q-switched lasers operating in the visible and near visible portion of the spectrum shows that the erbium laser offers promise as a relatively "safe laser." Key words: necrosis of cornea due to radiation, radiation injury, radiation intensity, lasers, experimental results, histopathology, monkeys. B'ecaus. e of the serious ocular threat Methods posed by laser devices operating in the An erbium laser was constructed in this labora- visible portions of the spectrum, less tory to deliver Q-switched laser pulses at 1.54/t. hazardous laser systems are being sought The dearth of erbium laser rods of even moder- by both the civilian and military com- ately good quality seriously restricted the design technique. The resulting erbium-glass laser con- munities. One approach is to utilize lasers sistently delivered up to 100 mj. of Q-switched that operate in spectral regions where the energy in a single 50 nsec. pulse. Between 100 ocular media are relatively opaque to the and 200 mj. output double pulsing occasionally incident radiation. In this respect the occurred, yielding two 50 nsec. pulses separated erbium laser offers a theoretical advantage by 200 nsec. Because of the quality of the laser based upon its emission spectrum in the rod, the beam cross section was quite irregular. 1 An elliptical cavity was used to couple the infra-red. Depending upon the host ma- linear flash lamp to the laser rod. Q-switching terial employed, the emission wavelength was accomplished by a rotating prism driven at of erbium varies from 1:53//, in glass to 20,000 r.p.m. and electronically synchronized to 1.64//, in yttrium-aluminum-garnet. The the flash lamp. A three-element quartz resonant transmission of the eye at the erbium reflector with a reflectivity of 65 per cent was used as the output mirror. A sapphire optical flat wavelengths is quite low (Fig. 1). Based inserted in the resonant cavity at the Brewster upon these considerations a series of ex- angle polarized the laser output. This was re- periments were conducted to study the quired because polarization-dependent beam split- ocular effects of the Q-switched erbium ters were used in the delivery-detection system. laser. The separate components were mounted on an optical bench yielding a total resonator length of 50 cm. A pulse-forming network consisting of From The Joint AMRDC-AMC Laser Safety 1300/xf capacitance in series with 850/th induc- Team, Frankford Arsenal, Philadelphia, Pa. tance provided a 3.5 msec, pulse through the Manuscript submitted Jan. 6, 1970; revised manu- flash lamp. Triggering was accomplished through script accepted March 20, 1970. an inline trigger transformer. 463 Downloaded from iovs.arvojournals.org on 09/28/2021 464 Lund et al. Investigative Ophthalmology June 1970 10' 10"1 10"2 UJ o z < z H 10-4 I0 10 1O"10 10"12 .4 .6 .8 1.0 1.2 1.4 1.6 1.8 WAVELENGTH - « Fig. 1. Spectral transmittance through human eye. Between 0.3 and 1.3fi, the curve is based on measurement of human ocular tissue2 Beyond 1.3^, the transmittance is that of a 2.2 cm. layer of pure H2O. A detection system and a delivery system to arsenide photodiode measured the duration and couple the laser energy into the eye of the experi- number of output pulses and a germanium photo- mental animal were constructed as shown in Figs. diode with an integrating network measured the 2 and 3. A low-power helium-neon laser beam energy. The portion of the beam passing through was coupled into the delivery system through a the beam splitter was incident upon the cornea beam splitter and carefully aligned to be colinear of the experimental animal. Calibration of the with the erbium laser beam, thus facilitating aim- detection system was accomplished by placing a ing and alignment of the system. After passing TRG 100 Ballistic Thermopile in the eye-exposure through attenuating and focusing optics, the er- position and comparing the photodiode output to bium laser beam was limited by an aperture 2 the thermopile output. This technique compen- mm. in diameter. Immediately beyond this aper- sated for the peculiarities of the aperture, beam ture, a beam splitter directed a portion of the splitters, and detectors by utilizing them in cali- energy to a diffuse reflecting surface where it was bration exactly as they were used in measurement. monitored by calibrated detectors. An indium- The calibration was checked immediately before Downloaded from iovs.arvojournals.org on 09/28/2021 Volume 9 Hazards of Q-switched laser 465 Number 6 alignment detectors laser ballistic thermopile i , I I I 'eye erbium laser 1 attenuator Fig. 2. Schematic diagram of the erbium experimental configuration. Fig. 3. Erbium experimental apparatus showing owl monkey positioned for exposure. and after each animal experiment, giving results kilogram) via the saphenous vein. The pupils reproducible to ±10 per cent over the experi- were dilated with phenylephrine hydrochloride mental period. (10 per cent) combined with cyclopentolate The animals used in these experiments were hydrochloride (1 per cent). Sutures of 3-0 silk owl monkeys (Aotus trivirgatus). Preanesthetic were placed in the upper eyelids to facilitate their medication consisted of a sedative dose of phen- manipulation. Physiologic saline was used to pre- cyclidine hydrochloride (0.25 mg. per kilogram) vent drying of the cornea. intramuscularly, and atropine sulfate (0.2 mg.) Immediately before exposure, the eyes were subcutaneously. Anesthesia was induced with so- carefully examined by slit lamp biomicroscopy dium pentobarbital (approximately 5 mg. per and ophthalmoscopy, and any abnormal eye was Downloaded from iovs.arvojournals.org on 09/28/2021 466 Lund et al. Investigative Ophthalmology June 1970 / \ 7 \ \ /I \ / != .1 / / / \ \ / j I-01 I of \\o 1 \ o / V >/ V .001 .8 .6 .4 .2 0 .2 .4 .6 .8 RADIUS - mm. Fig. 4. Profile of the focused erbium laser beam showing experimental data points and a theoretical Gaussian curve. rejected. The animal was placed in position in the determine the peak energy density within the delivery system and irradiated. Each corneal ex- focused beam. This posed the problem of measur- posure site was examined immediately, and de- ing the characteristics of the beam cross section tailed biomicroscopy and ophthalmoscopy were at the focus of the lens. A technique employing performed at 30 to 60 minutes following exposure. exposed Polaroid film was used for this purpose. Several eyes were observed at 1 day, 7 days, and When impacted by laser radiation, the emulsion 3 weeks following exposure. was burned from the film where the laser energy Pathologic examination was performed on all density exceeded a certain value. The film was eyes. The eyes were enucleated either immediately subjected to a series of exposures with the laser or from 1 to 14 days following exposure and at constant output, but with the beam attenuated fixed for 24 hours in 10 per cent formaldehyde. in step-wise fashion by calibrated neutral density Serial sections of paraffin-embedded specimens filters. Measurement of the diameter of the pro- were stained with hematoxylin and eosin and ex- gressively decreasing spot size allowed the rela- amined by light microscopy. tive energy density profile to be plotted (Fig. 4). Two techniques of exposure were utilized. In The beam at the focus was found to be approxi- the first series of experiments the direct output mately Gaussian. If the beam is assumed to be beam of the laser was employed without inter- Gaussian, it is possible to calculate the peak en- vening optical lenses; a total of 15 exposures were ergy density. For the purpose of computation the placed in 5 eyes. In the second series of experi- diameter of the beam spot is taken to be that ments a lens was used to focus the beam onto diameter at which the relative energy density the cornea of the experimental animal for a total falls to a value 1/e of the peak value. The peak of 41 exposures in 14 eyes. In order to define the energy density is then the total measured energy threshold level for damage, it was necessary to divided by the area of the spot so defined. Downloaded from iovs.arvojournals.org on 09/28/2021 Volume 9 Hazards of Qswitched laser 467 Number 6 Fjg. 5. Photograph of a fresh corneal lesion produced with the Q-switched erbium laser at 45 j./cm.2. Note the localized opacification of the epithelium, Bowman's membrane, and stroma with radiating folds in Descemet's membrane. Fig. 6. Epithelial facet at the site of a healed 10-day-old corneal lesion. The anterior stroma contains fibroblasts and inflammatory cells. Separation of stromal lamellae is artifactitious. {Hematoxylin and eosin; x500.) Downloaded from iovs.arvojournals.org on 09/28/2021 468 Lund et al. Investigative Ophthalmology June 1970 Results fications of Bowman's membrane and the In the first series of exposures using the anterior corneal lamellae occurred at the direct output beam of the laser, corneal impact site.
Load more

Recommended publications
  • CO2 - CO2 Laser Physics 111B: Advanced Experimentation Laboratory University of California, Berkeley
    CO2 - CO2 Laser Physics 111B: Advanced Experimentation Laboratory University of California, Berkeley Contents 1 CO2 Laser Description (CO2)1 2 The CO2 Laser Experiment Photos2 3 Before the 1st Day of Lab3 4 Objectives 4 5 Introduction 4 5.1 Safety Measures............................................ 4 6 Equipment 5 7 Standard Operating Procedure (SOP) for the CO2 Laser6 7.1 Alignment Procedure......................................... 6 7.2 Pumping-Out and Filling the Laser Tube ............................. 7 7.3 Power-On and -Off, and Maximizing Laser Power......................... 9 8 Experiments 11 8.1 Current-voltage Curve and Gas Pressure.............................. 11 8.2 Power Threshold ........................................... 11 8.3 Output Power Stability ....................................... 11 8.4 Laser Spectrum............................................ 12 8.4.1 Beam-Finding......................................... 12 8.4.2 The Spectrum Analyzer (Spectrometer).......................... 12 9 Apparatus Layout 15 10 References 16 1 CO2 Laser Description (CO2) 1. Note that there is NO eating or drinking in the 111-Lab anywhere, except in rooms 282 & 286 LeConte on the bench with the BLUE stripe around it. Thank you { the Staff. The carbon dioxide laser was the first high-powered infrared laser developed. The one in our laboratory is a new version that everything about it is something you can see, touch and adjust { from filling the tube with gas, aligning the optical elements to measuring the output power and wavelengths. Its output can exceed 10 watts of monochromatic radiation, enough to burn you in a fraction of a second. So be careful with what you vary. In this experiment, you will learn about molecular structure, light and optics, and gas discharges. You will develop skills in adjusting sensitive optical equipment.
    [Show full text]
  • C – Laser 1. Introduction the Carbon Dioxide Laser (CO2 Laser) Was One
    Generated by Foxit PDF Creator © Foxit Software http://www.foxitsoftware.com For evaluation only. C – laser 1. Introduction The carbon dioxide laser (CO2 laser) was one of the earliest gas lasers to be developed (invented by Kumar Patel of Bell Labs in 1964[1]), and is still one of the most useful. Carbon dioxide lasers are the highest-power continuous wave lasers that are currently available. They are also quite efficient: the ratio of output power to pump power can be as large as 20%. The CO2 laser produces a beam of infrared light with the principal wavelength bands centering around 9.4 and 10.6 micrometers. 2. Amplification The active laser medium is a gas discharge which is air-cooled (water-cooled in higher power applications). The filling gas within the discharge tube consists primarily of: o Carbon dioxide (CO2) (around 10–20%) o Nitrogen (N2) (around 10–20%) o Hydrogen (H2) and/or xenon (Xe) (a few percent; usually only used in a sealed tube.) o Helium (He) (The remainder of the gas mixture) The specific proportions vary according to the particular laser. The population inversion in the laser is achieved by the following sequence: 1) Electron impact excites vibrational motion of the nitrogen. Because nitrogen is a homonuclear molecule, it cannot lose this energy by photon emission, and its excited vibrational levels are therefore metastable and live for a long time. 2) Collisional energy transfer between the nitrogen and the carbon dioxide molecule causes vibrational excitation of the carbon dioxide, with sufficient efficiency to lead to the desired population inversion necessary for laser operation.
    [Show full text]
  • Introduction to Non-Arc Welding Processes
    Introduction to Non-Arc Welding Processes Module 2B Module 2 – Welding and Cutting Processes Introduction to Non-Arc Welding Processes Non-Arc Welding processes refer to a wide range of processes which produce a weld without the use of an electrical arc z High Energy Density Welding processes Main advantage – low heat input Main disadvantage – expensive equipment z Solid-State Welding processes Main advantage – good for dissimilar metal joints Main disadvantage – usually not ideal for high production z Resistance Welding processes Main advantage – fast welding times Main disadvantage – difficult to inspect 2-2 Module 2 – Welding and Cutting Processes Non-Arc Welding Introduction Introduction to Non-Arc Welding Processes Brazing and Soldering z Main advantage – minimal degradation to base metal properties z Main disadvantage – requirement for significant joint preparation Thermite Welding z Main advantage – extremely portable z Main disadvantage – significant set-up time Oxyfuel Gas Welding z Main advantage - portable, versatile, low cost equipment z Main disadvantage - very slow In general, most non-arc welding processes are conducive to original fabrication only, and not ideal choices for repair welding (with one exception being Thermite Welding) 2-3 High Energy Density (HED) Welding Module 2B.1 Module 2 – Welding and Cutting Processes High Energy Density Welding Types of HED Welding Electron Beam Welding z Process details z Equipment z Safety Laser Welding z Process details z Different types of lasers and equipment z Comparison
    [Show full text]
  • Lasers in Periodontal Surgery 5 Allen S
    Lasers in Periodontal Surgery 5 Allen S. Honigman and John Sulewski 5.1 Introduction The term laser, which stands for light amplification by stimulation of emitted radia- tion, refers to the production of a coherent form of light, usually of a single wave- length. In dentistry, clinical lasers emit either visible or infrared light energy (nonionizing forms of radiation) for surgical, photobiomodulatory, and diagnostic purposes. Investigations into the possible intraoral uses of lasers began in the 1960s, not long after the first laser was developed by American physicist Theodore H. Maiman in 1960 [1]. Reports of clinical applications in periodontology and oral surgery became evident in the 1980s and 1990s. Since then, the use of lasers in dental prac- tice has become increasingly widespread. 5.2 Laser-Tissue Interactions The primary laser-tissue interaction in soft tissue surgery is thermal, whereby the laser light energy is converted to heat. This occurs either when the target tissue itself directly absorbs the laser energy or when heat is conducted to the tissue from con- tact with a hot fiber tip that has been heated by laser energy. Laser photothermal reactions in soft tissue include incision, excision, vaporization, ablation, hemosta- sis, and coagulation. Table 5.1 summarizes the effects of temperature on soft tissue. A. S. Honigman (*) 165256 N. 105th St, Scottsdale, AZ 85255, AZ, USA J. Sulewski Institute for Advanced Laser Dentistry, Cerritos, CA, USA e-mail: [email protected] © Springer Nature Switzerland AG 2020 71 S. Nares (ed.), Advances in Periodontal Surgery, https://doi.org/10.1007/978-3-030-12310-9_5 72 A.
    [Show full text]
  • Laser-Based Treatment of the Aging Face for Skin Resurfacing: Ablative
    PART 3 • Aesthetic Surgical Procedures Laser-based Treatment of the Aging Face for Skin Resurfacing: 34 Ablative and Non-ablative Lasers Omar A Ibrahimi MD PhD , Nazanin Saedi MD , and Suzanne L. Kilmer MD several years has shifted towards fractional resurfacing CHAPTER SUMMARY (both ablative and non-ablative) as described by Manstein • Many aspects of dermatoheliosis are amenable to and colleagues, 4 due to its faster recovery time and safer treatment with a variety of ablative and non-ablative side-effect profi le. Nonetheless, it provides an important lasers and light sources. • Ablative laser skin resurfacing offers the most substantial historical framework for understanding cutaneous resurfac- clinical improvement, but is associated with greater ing and in a few instances, may be preferable over fractional postoperative recovery. resurfacing for certain dermatological conditions. • Non-ablative laser skin remodeling is a good alternative for patients who desire modest improvement of Proper patient selection dermatoheliosis with a limited post-treatment recovery period. A focused history should be obtained prior to any resurfac- • Fractionated laser systems provide the benefi ts of higher ing procedure. In particular, it is important to document if energy treatments with fewer side-effects and faster the patient has had any previous procedures or any contra- recovery than traditional lasers. indications to resurfacing. Ablative laser resurfacing may • Continued developments in laser technology will lead to greater effi cacy with an improved safety profi le. unmask hypopigmentation or fi brosis produced by prior dermabrasion, cryosurgery, or phenol peels. In addition, the presence of fi brosis may limit the vaporization potential of ablative lasers, thereby decreasing clinical effi cacy.
    [Show full text]
  • Devices for Rejuvenation of the Aging Face P
    Review Devices for Rejuvenation of the Aging Face P. Mark Neal, MD; Adrian Dobrescu, MD; John Chapman, MD; Mara Haseltine, MD Over the last 30 years, there has been a substantial increase in the number of ablative and nonablative devices that can be used to treat the signs of skin aging. Some devices have found new indications or new technology to refine older indications. In this article, we review the ablative and nonablative devices that are currently available for photorejuvenation of the aging face. Cosmet Dermatol. 2012;25:412-418. n the field of cosmetic dermatology, there are a vari- side effects, such as scarring and dyspigmentation. Patients ety of options to reverse the physical signs of aging. also experienced substantial downtime (approximately Many of these options include treatment with 2 weeks) following the procedure. Because of the need for devicesCOS that induce remodeling of the dermis andDERM more controlled ablation with less severe side effects, the epidermis, resulting in a more youthful appearance erbium:yttrium-aluminum-garnet (Er:YAG) laser as well I(Table). In the 1980s, the continuous wave CO2 laser was as the high-energy superpulsed and scanning CO2 lasers introduced with impressive results in reversing the signs were developed for cutaneous use. These newer devices of aging but also was associated with a high potential for help control the excess thermal injury that previously side effects and substantial downtime. Since then, many had led to unwanted side effects. The Er:YAG laser offers new devices have been made available to laser surgeons modes of variable long- and short-pulse durations to that Dooffer varying degrees of facial Notrejuvenation with fewer promote Copy more controlled ablation.
    [Show full text]
  • Laser Disposal Guide
    Laser Disposal Guide Introduction Lasers have a finite lifetime, which is based on use, experimental needs or technological advances. The goal of this guide is to provide guidance for the laser user and in particular, the LBNL Surplus/Excess staff and EHS waste disposal staff when dealing with lasers at the end of their life cycle. For the purpose of this guide, we will break lasers into several different types: gas, solid-state rod, liquid, and semiconductor. Laser systems also come in a variety of sizes, which does not relate to their optical laser output. In addition, when a laser is disposed of, a power supply often travels with it. Standard electrical safety protocols adequately address the power supply and will not be addressed in this document. All lasers that utilize electricity as their main energy source and were manufactured prior to July 1, 2006, will most likely have Lead in their printed circuit boards. Therefore these boards need to be disposed of as electronic waste (e-waste). There are United States regulations such as export control and European Reduction of Hazardous Materials regulations, known as RoHS rules, that affect how and the manner surplus lasers are to be dealt with. Here is in California there is the CA Dept. of Toxic Substances. Document prepared by Ken Barat & Justine Woo April 2012 Page | 1 Table of Contents Action Points/Questions to Ask Yourself .....................................................................................................3 User Responsibilities ....................................................................................................................................3
    [Show full text]
  • I Aperture Coupling of a Carbon Dioxide Laser
    I ‘ APERTURE COUPLING OF - -. A CARBON DIOXIDE LASER - . ~, ?-. L) EMPLOYING A NEAR-CONFOCAL OPTICAL RESONATOR / I JOHN H. McELROY HAROLD E. WALKER CFSTI PRICE(S) $ 1) Hard copy (HC) &o , - I X-524-67-513 APERTURE COUPLING OF A CARBON DIOXIDE LASER EMPLOYING A NEAR-CONFOCAL OPTICAL RESONATOR John H. McElroy and Harold E. Walker October 1967 GODDARD SPACE FLIGHT CENTER Greenbelt, Maryland X- 524- 67- 513 APERTURE COUPLING OF A CARBON DIOXIDE LASER EMPLOYING A NEAR-CONFOCAL OPTICAL RESONATOR John H. McElroy Harold E. Walker October 1967 Henry H. Plotkin Head, Optical Systems Branch I ,'> , + '8 <A"'J , bz4 Robert J. Coates Chief, Advanced Development Division GODDARD SPACE FLIGHT CENTER Greenbelt, Maryland rntCEDiNG PAGE BLANK NOT FILMED. SUMMARY Materials difficulties encountered at the 10.6 micron wave- length of the C02 laser oftendictate that the laser output be obtained by aperture coupling through a hole in the output mirror. This doc- ument presents the results of measurements made on an aperture coupled carbon dioxide laser using a near-confocal optical resonator. The effects of coupling hole diameter and mirror spacing are related to laser multimode power output and mode structure. It is found that odd-symmetric modes dominate and, if a simple mode structure is required, with maximum axial power density, the diameter of the output coupling hole must be restricted. iii CONTENTS Page INTRODUCTION ........................ 1 EXPERIMENTAL ARRANGEMENT. ............... 2 EXPERIMENTAL RESULTS ................... 4 ACKNOWLEDGEMENTS .................... 8 REFERENCES ......................... 8 ILLUSTRATIONS Figure 1 Experimental Carbon Dioxide Laser ......... 2 Multimode Laser Power Output as a Function of Mirror Spacing and Coupling Aperture Diameter . ..... 3 Power Enhancement with an Iris Diaphragm in Laser Cavity.
    [Show full text]
  • Laser Therapy for the Treatment of Morphea: a Systematic Review of Literature
    Journal of Clinical Medicine Review Laser Therapy for the Treatment of Morphea: A Systematic Review of Literature Paulina Szczepanik-Kułak * , Małgorzata Michalska-Jakubus and Dorota Krasowska Chair and Department of Dermatology, Venerology and Paediatric Dermatology, Medical University of Lublin, 20-081 Lublin, Poland; [email protected] (M.M.-J.); [email protected] (D.K.) * Correspondence: [email protected] Abstract: Morphea, also known as localized scleroderma (LoS), comprises a set of autoimmune sclerotic skin diseases. It is characterized by inflammation and limited thickening and induration of the skin; however, in some cases, deeper tissues might also be involved. Although morphea is not considered a life-threatening disease, the apparent cosmetic disfigurement, functional or psychosocial impairment affects multiple fields of patients’ quality of life. Therapy for LoS is often unsatisfactory with numerous treatments that have only limited effectiveness or considerable side effects. Due to the advances in the application of lasers and their possible beneficial effects, the aim of this study is to review the reported usage of laser in morphea. We present a systematic review of available literature, performed with MEDLINE, Cinahl, Central, Scopus, Web of Science, and Google Scholar databases. We identified a total of twenty relevant studies (MEDLINE n = 10, Cinahl n = 1, Central n = 0, Scopus n = 2, Web of Science n = 5, Google Scholar n = 2) using laser therapy for LoS. Eight studies were focused on the use of PDL, six on fractional lasers (CO2 and Er:YAG), four on excimer, and two on either alexandrite or Nd:YAG. Keywords: morphea; localized scleroderma; laser therapy Citation: Szczepanik-Kułak, P.; Michalska-Jakubus, M.; Krasowska, D.
    [Show full text]
  • Invited Review Q-Switched Laser Treatment of Tattoos
    Lasers in Medical Science 1997, 12:89-98 Invited Review Q-switched Laser Treatment of Tattoos K.M. CESARIO-KELLY, J.S. NELSON Departments of Surgery and Dermatology, Beckman Laser Institute and Medical Clinic, University of California, Irvine, USA Correspondence to J.S. Nelson, Beckman Laser Institute and Medical Clinic, University of California, Irvine, 1002 Health Sciences Road East, Irvine, CA 92612, USA Paper received 16 October 1996; accepted pending revision 1 November 1996; accepted in final form 10 February 1997 (London) Abstract. In the last decade, Q-switched lasers have expanded the clinician's ability to treat decorative, cosmetic and traumatic tattoos without scarring. Previous methods of gross tissue removal with resultant scarring have been replaced by the highly selective removal of tattoo pigment with minimal changes in skin texture or pigmentation. This article reviews use of the Q-switched ruby, Q-switched neodymium yttrium-aluminum-garnet and Q-switched alexandrite lasers in the clinical management of patients with tattoos. INTRODUCTION adjacent dermal structures occurs and, there- fore, virtually all patients have some form of Between 5 and 10% of the adult population secondary scar formation. have a tattoo for either decorative or cosmetic purposes or as a result of trauma or medical treatment. The word tattoo is derived from the SELECTIVE PHOTOTHERMOLYSIS Polynesian (Marquesan) word tatu, and refers to the accidental or volitional acquisition of The laser has many inherent physical proper- pigmented particles in the skin. A wide variety ties that contribute to its ability to effect a of agents and techniques have been tried over specific biological outcome.
    [Show full text]
  • Medical Indications for Pulsed Dye Laser Treatment
    MEDICAL INDICATIONS FOR PULSED DYE LASER TREATMENT DESCRIPTION Pulsed dye laser delivers energy at a wavelength and duration that has been optimized for the selective treatment of vascular lesions. It is used in the treatment of warts, port wine stains, hemangiomas, hypertrophic scars, and telangiectasias. Pulsed dye lasers have been used as an alternative to surgical excision or carbon dioxide laser. The pulsed-dye laser has been shown to be effective in treating glomangiomas in the face and neck, as surgical excision may not be practical in these cosmetically sensitive areas. Requests for pulsed dye laser treatment is considered on a case-by-case basis, and is generally considered cosmetic in nature UNLESS specific administrative and medical necessity criteria are met. DECISION CRITERIA Administrative 1. Referral required from member’s PCP along with supporting documentation. This shall include: (at minimum) a. member’s name and THC plan number b. proposed date of procedure, facility, name, applicable diagnostic and procedure codes c. name and contact information of surgeon or requesting provider d. progress notes that includes member’s current and past medical history, treatment to date and response; appropriate diagnostic tests results e. Photographs of affected area(s)-highly recommended 2. Services must be performed by a Plan affiliated or contracted provider, if not, then plan approval of treating provider & facility 3. Medical necessity review and prior approval 4. Services must not be considered cosmetic in nature 5. Member must have current eligibility on date of service 6. Must not have been recently treated with isotretinoin (Accutane) G:\Lotshare\BENEFIT DETERMINATION (CRITERIA)\27.
    [Show full text]
  • Molecular Weight Determination of Peptides and Proteins by ESI and MALDI
    [1] molecular weight determination by ESI and MALDI 1 [1] Molecular Weight Determination of Peptides and Proteins by ESI and MALDI By KERSTIN STRUPAT Abstract Several topics are covered, namely, general aspects important for mass determination of peptides and proteins, sample preparation for both ESI and MALDI, and various mass analyzers coupled to these ionization techniques. Finally, the discussion is carried out on peptide and protein mass analysis as related to accuracy and precision of mass determination for both ESI–MS and MALDI–MS. Introduction The techniques of electrospray/ionization (ESI) and matrix‐assisted laser desorption/ionization (MALDI) have revolutionized biological mass spectrometry (MS). All state‐of‐the‐art biochemistry and biology labora- tories possess at least one of these ionization techniques and, in general, have access to both of them. Parallel to and motivated by the development of these techniques, a diminution of chromatographic separation techni- ques and purification techniques has taken place, and the success of ESI and MALDI in biochemistry and biology is also due to the possibility of direct or indirect coupling of the ionization techniques to appropriate separation and purification techniques. Both ionization techniques are applicable to peptides and proteins (Yates, 1998), DNA and RNA (Gross, 2000), glycoconjugates, and synthetic polymers (Nielen, 1999). Considerable information can be derived from mass spectra of biological samples such as peptides and proteins. Besides the determina- tion of the molecular mass M of a given compound (often named molecular weight Mr, which is not quite correct because no weight or force, respec- tively, is measured by MS) and the identification of proteins by accurate mass determination of their proteolytic fragments, mass spectrometry is capable of providing structural information (i.e., sequences) for peptides.
    [Show full text]