Improvements To Modeling Of Port Wine Stain Laser Treatment
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Improvements To Modeling Of Port Wine Stain Laser Treatment
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Author : Willem Verkruysse
language : en
Publisher:
Release Date : 1998
Improvements To Modeling Of Port Wine Stain Laser Treatment written by Willem Verkruysse and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1998 with categories.
Simulating The Colour Of Port Wine Stain Skin
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Author : Thomas Lister
language : en
Publisher:
Release Date : 2013
Simulating The Colour Of Port Wine Stain Skin written by Thomas Lister and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
Currently, laser treatments for Port Wine Stain (PWS) lesions are considered the choice therapy, but response is poor or treatments are ineffective for around half of patients. It is proposed in this thesis that improvements to the effectiveness of laser treatment can be achieved through the acquisition of estimated PWS vessel number density, depths and diameters for each individual lesion. Information regarding PWS vessel architecture is found to be contained within the colour of the lesion. Presented in this thesis is a method of extracting this information through colour measurements and the inverse application of a skin model. Colour measurements are performed on 14 participants using a Konica-Minolta CM2600d spectrophotometer employing a xenon flashlamp illumination source and an integrating sphere. Light transport is simulated through an 8 layer mathematical skin model inclusive of horizontal, pseudo-cylindrical PWS blood vessels using a new Monte Carlo programme. Within the programme, model parameters were adjusted in an iterative process and skin colour was reproduced with a mean discrepancy of 1.9% reflection for clinically normal skin (24 datasets) and 2.4% for PWS skin (25 datasets). The programme estimated anatomical properties of the measured regions of skin, yielding epidermal melanin volume fractions from 0.4% to 3.3% and mean melanosome diameters from 41 nm to 384 nm across the participant group. The response to laser treatment was assessed for 10 participants through colour measurements taken immediately before and at least 6 weeks after treatment and through expert analysis of photographs for 9 participants taken at these times. Treatment response was not found to correlate directly with the pre-treatment melanin parameters estimated by the programme. Mean depths, diameters and number densities of PWS vessels were also estimated by the programme before and after treatment. These parameters were compared to data obtained from Optical Coherence Tomography (OCT) images for 5 participants. Number densities and diameters predicted by the simulation varied by no more than 10% from the values determined by OCT for 4 and 5 out of 7 regions respectively. Mean depths predicted by the simulation did not correspond with those determined by OCT however. This may be a result of the limited contribution of deeper vessels to the colour of PWS skin. Predicted PWS parameters were compared to treatment response assessed by colour measurement for 10 participants and by photographic analysis for 9 of these. Predicted vessel number densities were not found to correspond with treatment response. Vessel diameters predicted by the simulation correlated with treatment response when compared with the pulse lengths selected for treatment. Optical coefficients derived from the skin model were used to estimate appropriate laser treatment radiant exposures at the predicted mean vessel depths and these radiant exposures corresponded strongly with the treatment response. Suggestions for improvements in the predictions of melanosome diameters through changes in the adjacent skin minimisation procedure within the programme are discussed. The apparent underestimation of PWS blood vessel number densities and mean depths (compared to biopsy studies) may be a result of the reduced influence of deeper PWS vessels upon skin colour. Further investigation, including modifications to the PWS vessel minimisation procedure within the programme, would be necessary to determine whether improvements in these predictions may be achievable. The results of the study show that the new Monte Carlo programme is capable of extracting, from measurements of skin colour, realistic estimates of PWS skin characteristics which can be used to predict treatment response and therefore inform treatment parameters on an individual PWS.
Computational Modeling Of Laser Therapy Of Port Wine Stains Based On Reduced Scattering Method
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Author : Sangeetika Ruchi
language : en
Publisher:
Release Date : 2015
Computational Modeling Of Laser Therapy Of Port Wine Stains Based On Reduced Scattering Method written by Sangeetika Ruchi and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
Laser treatment of Port-Wine Stains (PWS) was studied computationally by assuming a two dimensional skin model and using the reduced scattering method for the photon energy transport. The energy deposited during the laser irradiation of skin was based on a Gaussian laser profile. Alternating Direction Implicit finite difference method was used to investigate the effect of cryogenic spray cooling during laser irradiation on the skin temperature response. The computational model was developed in MATLAB and validated using experimental results available in the literature. Simulations were first run for the case of laser irradiation with a continuous spurt of cryogen which showed a drastic drop in the temperature rise as compared to the case without any cooling method. Then the effect of intermittent cryogen cooling accompanying laser irradiation was analyzed. To understand the outcome of preheating on the treatment procedure, preheating was computational modeled with continuous as well as intermittent cryogen cooling. It was found that by preheating the skin it is possible to raise the temperature of the blood vessels (responsible for PWS), by minimizing the danger of vessel necrosis. Preheating the skin increases the temperature of the entire skin model (layers of epidermis, dermis and blood) but since cryogen provides only selective cooling it protects the epidermis from any form of thermal injury, without affecting the temperature of blood vessels present in the dermis layer. It was also found that using cryogen spurt in intermittent intervals instead of a long continuous spurt further reduces the risk of vessel necrosis and other forms of thermal injury. Results showed that the maximum temperature rise is a weak function of the surface heat transfer coefficient however the temperature in the epidermis layer is strongly dependent on the surface heat transfer.
Comprehensive Biomedical Physics
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Author :
language : en
Publisher: Newnes
Release Date : 2014-07-25
Comprehensive Biomedical Physics written by and has been published by Newnes this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014-07-25 with Science categories.
Comprehensive Biomedical Physics, Ten Volume Set is a new reference work that provides the first point of entry to the literature for all scientists interested in biomedical physics. It is of particularly use for graduate and postgraduate students in the areas of medical biophysics. This Work is indispensable to all serious readers in this interdisciplinary area where physics is applied in medicine and biology. Written by leading scientists who have evaluated and summarized the most important methods, principles, technologies and data within the field, Comprehensive Biomedical Physics is a vital addition to the reference libraries of those working within the areas of medical imaging, radiation sources, detectors, biology, safety and therapy, physiology, and pharmacology as well as in the treatment of different clinical conditions and bioinformatics. This Work will be valuable to students working in all aspect of medical biophysics, including medical imaging and biomedical radiation science and therapy, physiology, pharmacology and treatment of clinical conditions and bioinformatics. The most comprehensive work on biomedical physics ever published Covers one of the fastest growing areas in the physical sciences, including interdisciplinary areas ranging from advanced nuclear physics and quantum mechanics through mathematics to molecular biology and medicine Contains 1800 illustrations, all in full color
Proceedings Of Laser Surgery
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Author :
language : en
Publisher:
Release Date : 2004
Proceedings Of Laser Surgery written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with Lasers in surgery categories.
Principles And Practices In Cutaneous Laser Surgery
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Author : Arielle Kauvar
language : en
Publisher: CRC Press
Release Date : 2005-09-20
Principles And Practices In Cutaneous Laser Surgery written by Arielle Kauvar and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005-09-20 with Medical categories.
Will full-color photographs throughout, this reference demonstrates and assesses various technologies and methods to effectively perform laser treatments for a variety of cutaneous disorders-emphasizing the selection of the appropriate laser for each clinical situation, practical treatment guidelines, and the avoidance of complications in the pract
Lasers In Dermatology And Medicine
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Author : Keyvan Nouri
language : en
Publisher: Springer Science & Business Media
Release Date : 2011-09-06
Lasers In Dermatology And Medicine written by Keyvan Nouri and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011-09-06 with Medical categories.
Laser technology is constantly evolving and progressing. The use of laser therapy is vastly expanding and for this reason a medical book of this magnitude is necessary. Lasers and Light Therapy includes an up-to-date comprehensive look at lasers and light therapy not only in the field of Cutaneous Laser Surgery, but in other medical specialties as well.
Diagnostic Optical Spectroscopy In Biomedicine
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Author :
language : en
Publisher:
Release Date : 2005
Diagnostic Optical Spectroscopy In Biomedicine written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with Biosensors categories.
Optical Thermal Response Of Laser Irradiated Tissue
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Author : Ashley J. Welch
language : en
Publisher: Springer Science & Business Media
Release Date : 2011-01-15
Optical Thermal Response Of Laser Irradiated Tissue written by Ashley J. Welch and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011-01-15 with Science categories.
The second edition maintains the standard of excellence established in the first edition, while adjusting the content to reflect changes in tissue optics and medical applications since 1995. The material concerning light propagation now contains new chapters devoted to electromagnetic theory for coherent light. The material concerning thermal laser-tissue interactions contains a new chapter on pulse ablation of tissue. The medical applications section now includes several new chapters on Optical Coherent Tomography, acoustic imaging, molecular imaging, forensic optics and nerve stimulation. A detailed overview is provided of the optical and thermal response of tissue to laser irradiation along with diagnostic and therapeutic examples including fiber optics. Sufficient theory is included in the book so that it is suitable for a one or two semester graduate or for senior elective courses. Material covered includes (1) light propagation and diagnostic application; (2) the thermal response of tissue and therapeutic application; (3) denaturation; and (4) ablation. The theory and applications provide researchers with sufficient detail that this volume will become the primary reference for laser-tissue interactions and medical applications.
The Role Of Dynamic Cooling In Improving Clinical Efficacy During Pulsed Dye Laser Treatment Of Port Wine Stain In Chinese
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Author : Chun-Hung Chiu
language : en
Publisher:
Release Date : 2017-01-26
The Role Of Dynamic Cooling In Improving Clinical Efficacy During Pulsed Dye Laser Treatment Of Port Wine Stain In Chinese written by Chun-Hung Chiu and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-01-26 with categories.
This dissertation, "The Role of Dynamic Cooling in Improving Clinical Efficacy During Pulsed Dye Laser Treatment of Port Wine Stain in Chinese" by Chun-hung, Chiu, 趙俊雄, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled The Role of Dynamic Cooling in Improving Clinical Efficacy during Pulsed Dye Laser Treatment of Port Wine Stain in Chinese submitted by Chiu Chun Hung for the degree of Master of Philosophy at the University of Hong Kong in July 2003 Port-wine stain (PWS) is a form of congenital vascular malformation that affects 0.5 % of newborns and is commonly associated with psychosocial impairment. Pulsed dye laser (PDL) in conjunction with dynamic or cryogen spray cooling (CSC) is effective in improving efficacy and safety in the treatment of PWSs in Caucasians. However, for dark-skinned patients such as Chinese, only retrospective studies have been performed. The purpose of this study is to prospectively compare the clinical efficacy and acute and long-term adverse effects of PDL alone and PDL in conjunction with CSC (PDL-CSC) for the treatment of PWSs in Chinese patients. Chinese patients with previously untreated PWSs were recruited. In every patient, a pre-defined test area on the PWS was treated. Half of the tested area was treated with PDL alone and the contralateral half was treated with PDL-CSC. The degree of PWS blanching was objectively assessed by spectrophotometer. Changes in skin elasticity were objectively detected by cutometer. All measurements were taken at baseline and before each subsequent laser session. Patients were interviewed immediately after treatment and again the following week with a visual analog scale questionnaire to measure the degree of pain and swelling. The occurrence of blisters was noted during each follow-up visit. Patients were also evaluated for evidence of long-term effects such as dyspigmentation and scarring. Thirty-five patients (13 male and 22 female) were enrolled, and 131 treatment sessions were performed in this study. Statistically significant higher fluences 2 2 were used on the PDL-CSC treated halves (6.5 J/cm for PDL alone, 10.7 J/cm for PDL-CSC). The percentage change in the a* value from spectrophotometry was significantly greater (24.8 % for PDL alone, 40.8 % for PDL-CSC), and hence more PWS blanching after treatment for PDL-CSC. No significant differences were found in important cutometer parameters after three treatments with PDL alone or PDL-CSC. The immediate pain scores were significantly higher for PDL alone (score 3.90) than for PDL-CSC (score 3.12). Blisters were significantly more common on the side that was treated by PDL alone (25 %) than PDL-CSC (15 %). The overall incidence of long-term effects was not significantly different between PDL alone and PDL-CSC. PDL-CSC was also the preferred treatment modality for most patients (72.5 %). To summarize, PDL-CSC is more effective than PDL alone in the blanching of PWSs in Chinese patients after three or more treatment sessions. PDL-CSC is also better tolerated, and higher fluences can be used with less blistering. The determination of optimal parameters for laser irradiation and dynamic cooling is still necessary to achieve consistent blanching in the treatment of dark-skinned patients. DOI: 10.5353/th_b2666148 Subjects: Dye lasers Skin diseases - Cryosurgery