Medical Laser Devices Research Articles

Фотодинамическая терапия при дистрофических заболеваниях вульвы

Dystrophic diseases of the vulva (DDV) are a group of diseases that have not been fully studied and are characterized by pain, itching, dyspareunia, dysuria, which significantly reduce the quality of life of patients, leading to vegetative-vascular and neurological disorders. Despite many different approaches, the problem of treating vulvar DDV remains unresolved, and among clinicians there is no single approach to treatment, which was the basis for studying the effectiveness of photodynamic therapy (PDT) with local application of a photosensitizer in patients with DDV. As part of the study, 35 patients with DDV were examined and treated. REVIXAN-DERMA gel was used as a photosensitizer, irradiation of the vulva was carried out using a medical laser device "LAMI" with a wavelength of 660 nm. One month after PDT of the vulva, we noted a clinical recovery in 70% of patients (no complaints), a normal vulvoscopic picture was observed in 60% of patients – epithelialization of cracks and erosions, restoration of the thickness of the epithelium, restoration of normal skin pattern, in the remaining 40% patients – epithelization of cracks and erosions, a decrease in the area of damage, restoration of the thickness of the epithelium was noted, in 70% of patients the cytogram was within the normal range, cells with signs of intraepithelial changes and malignancy were not found, in 30% of patients – a small number of horny scales, cells with signs of intraepithelial changes and malignancy were not found. During the PDT procedure of the vulva, no complications or side effects were registered. Thus, the results of the study after the use of PDT of the vulva with local application of the photosensitizer REVIXAN-DERMA gel indicate the effectiveness, safety and prospects of the method in the treatment of degenerative diseases of the vulva.

Application of photodynamic inactivation against pathogens of urinary tract infections

Photodynamic inactivation (PDI) is an alternative to antibiotic therapy method for biocidal action against microorganisms, which can be used for lithotripsy and sanitation of the bladder cavities. Objective. Selection of parameters and application PDI against uropathogenic microorganisms. Materials and Methods. In this study we used bacterial strains isolated from urine samples of patients. Differentiation media and biochemical plates were used for identification of microorganisms. The sensitivity of uropathogenic microorganisms to PDI was studied on pure cultures and in native urine. The photosensitizer “Photoditazine” (50 µg/ml) was used in the work, as well as Triton X-100 (5 % vol.) was applying to increase the permeability of the cell wall of gram-negative microorganisms. The samples were irradiated by a medical laser device “Latus-K” with a wavelength of 662 nm. To assess the effectiveness of PDI, the values of the logarithmic decrease of colony-forming unit (CFU) of the microorganisms were calculated. Statistical analysis was made by Statistica 10.0 and Mann-Whitney criterion. Results. 50 strains of uropathogens belonging to 18 species were isolated from 36 samples of native urine. Among them, the most common were S. aureus, E. coli, P. aeruginosa, K. pneumoniae. The value of logarithmic decrease in CFU for gram-positive bacteria ranged from 5 to 6, which corresponds to inactivation 99.999-99.9999% of bacterial cells in a sample. For gram-negative strains, this value was slightly lower and ranged from 4 to 5.5, which, nevertheless, corresponds to inactivation 99.99-99.999% of CFU bacteria. The addition of Triton X-100 increase the efficiency from 46% to 99.99% for E. coli, from 99% to 99.99% for P. mirabilis, from 16% to 94% for K. pneumoniae and from 97% to 99.999% for P. aeruginosa. It should be noted that the PDI was affect microorganisms both in isolated pure cultures and in native urine. Conclusions. Photodynamic inactivation may be considered as an alternative to antibiotic therapy method of biocidal action against uropathogenic microorganisms.

Picosecond Laser-Induced Photothermal Skin Damage Evaluation by Computational Clinical Trial.

Computational clinical trial (CCT) in the field of laser medicine promotes clinical application of novel laser devices, because this trial carried out based on numerical modeling of laser-tissue interactions and simulation of a series of treatment process. To confirm the feasibility of the computational clinical trial of skin treatment with a novel picosecond laser, this paper presents an evaluation method of the safety. In this method, the light propagation and thermal diffusion process after ultrashort light pulse irradiation to a numerical skin model is calculated and the safety based on the photothermal damage is evaluated by computational modeling and simulation. As an example, the safety of a novel picosecond laser device was examined by comparing with several laser devices approved for clinical use. The ratio of the maximum thermal damage induced by picosecond laser irradiation was 1.2 × 10-2 % at the epidermis, while that caused by approved laser irradiation was 99 % at the capillary vessels. The numerical simulation demonstrated that less thermal damage was observed compared with the approved devices. The results show the safety simulated by photothermal damage calculation was consistent with the reported clinical trials. This computational clinical trial shows the feasibility of applying computational clinical trials for the safety evaluation of novel medical laser devices. In contrast to preclinical and clinical tests, the proposed computational method offers regulatory science for appropriately and quickly predicting and evaluating the safety of a novel laser device.

Capabilities of Autodyne Reception in Medical СО2 Laser Devices

The generation characteristics and the capabilities of autodyne reception in single mode CO 2 lasers with pulse-periodic pumping of the active medium used in medical laser devices are investigated. It has been demonstrated that medical laser device based on CO 2 laser model DIAMOND C-30A (Coherent Сo.) has the best long-term laser power stability ((2–3)%), while the setup with CO 2 laser model 48–2W (Synrad Сo.) has the best short-term stability (0.62%). Amplitude-frequency characteristics of autodyne reception were studied for lasers of these devices. Power spectra of the autodyne signal appearing during evaporation of fat and muscle tissues under CO 2 laser radiation of the three types of laser devices were recorded. It has been shown that all these laser devices allow to detect the autodyne signal during evaporation of biological tissues. The medical laser setup with CO 2 laser model 48–2W has the highest signal-to-noise ratio during detection of laser backscattered radiation. This is due to the fact that this laser has larger autodyne amplification and better short-term power stability. The results can be used in the development of smart laser surgical systems with feedback.

レーザー医療機器の保守管理の現状と問題点に関する研究

レーザー医療機器の保守管理の現状と問題点に関する研究

Design aspects of medical laser devices

Design aspects of medical laser devices

COMPARATIVE ASSESSMENT OF THE EFFICACY OF PHOTODYNAMIC THERAPY OF BASAL CELL SKIN CANCER WITH THE INTRALESIONAL ADMINISTRATION OF RADACHLORIN AND FOTODITAZIN

Актуальность. Фотодинамическая терапия (ФДТ) все чаще применяется для неинвазивной, в процессе фотохимической реакции, деструкции базальноклеточного рака кожи. Надежная доказательная база эффективности при этом отсутствует. Цель – сравнительная оценка объективного ответа базальноклеточного рака кожи при его различных клинических формах, стадиях, гистологических типах, характере течения и локализации на ФДТ с внутриочаговым введением фотосенсибилизаторов Радахлорина и Фотодитазина. Материал и методы. В период с марта 2007 по март 2010 г. в исследование включили 74 больных первичным и рецидивным, солитарным (язвенная клиническая форма – 40,5% пациентов, поверхностная – 24%, нодулярная – 21,5%, склеродермоподобная – 14%) базальноклеточным раком кожи Ι–ΙI стадии (преимуществен- но Т₂N₀M₀); с неблагоприятной в отношении развития рецидива и неудобной для других методов лечения локализацией; с однотипным, сложным гистологическим вариантом строения и типом «морфеа». Пациентам проводился 1 курс ФДТ с внутриочаговым введением фотосенсибилизаторов хлоринового ряда: I группе (n = 45) вводили Радахлорин (в объеме 0,5–1 мл на 1 см² поверхности опухоли), II группе (n = 34) – Фотодитазин (в объеме 0,3–0,5 мл на 1 см² поверхности опухоли). Для всех пациентов световая доза составляла 300 Дж/см², источником света была медицинская лазерная установка ЛАМИ с длиной волны излучения 662 ± 3 нм, класс II А. В качестве первичного результата была выбрана клинически и цито- логически оцененная степень регресса очага через 3 месяца после его лечения, в качестве вторичных результатов – устойчивая клиническая и цитологическая реакция на месте бывшей опухоли через 12 месяцев после лечения. В дальнейшем безрецидивный период оценивался ежегодно до 5 лет после лечения. Дополнительно регистрировали побочные реакции на лечение до 2 месяцев и определяли косметический результат через 12 месяцев после ФДТ. Pезультаты лечения оценены у всех больных. Результаты. Установлен полный регресс базальноклеточного рака кожи у 43 (95,5%) пациентов из I группы и у 31 (91,2%) – из II группы. Частичный регресс отмечался у 2 (4,5%) и 3 (8,8%) больных соответственно, опухоли у этих пациентов были излечены в дальнейшем повторными курсами ФДТ. В обеих группах ближайший результат лечения у больных разными клиническими формами базальноклеточного рака кожи в стадии Т₁N₀M₀ не различался (p > 0,05), отмечено статистически значимое улучшение результата лечения язвенной формы опухоли в стадии Т₂N₀M₀ – 92,8% в I группе и 77,8% во II группе (р < 0,05). Отдаленные наблюдения выявили 5-летнее безрецидивное течение болезни у 42 (97,7%) из 43 излеченных пациентов I группы и 30 (96,8%) из 31 во II группе. Побочные эффекты наблюдались у всех больных, однако ограничивались кратковременными, неизбежными нежелательными реакциями в виде гиперемии, отека, экссудации, парестезии, боли. У 8% пациентов I группы и 6% больных II группы было повышение артериального давления. Отличный и хороший косметический результат после ФДТ отмечен у большинства пациентов – у 74,4% в I группе и 77,4% во II группе. Заключение. ФДТ с использованием внутриочагового введения фотосенсибилизаторов Радахлорин и Фотодитазин является эффективным вариантом лечения любой клинико-морфологической разновидности базальноклеточного рака кожи, сопровождается минимальными побочными реакциями и приемлемым косметическим результатом.

医用レーザー機器開発の歴史および臨床使用に対する提言

Recently medical laser devices have become to be the clinically-essential equipment for proper diagnosis and treatments. New laser equipment and peripheral technologies have been developed since 1980s, and currently the medical laser devices have many functions for various clinical indications. We, the users of medical laser devices, are demanded to enhance the knowledge and skills concerning about new laser technologies. And more, the users should recognize that the daily checking of laser devices, such as the output of laser beam, the irradiation pattern, the optical plane and etc., is needed for the reproducibility of laser treatment and the laser safety. We have to intensify the activity to raise awareness for importance of the scheduled checking of laser devices.

Approval Review of Medical Laser Devices

Approval Review of Medical Laser Devices

Cancers Cured by Bio Electrons Photons

The K-BTE medical laser device releases sheaves of “biological electricity” through elementary laser beams of bio electron's photons. These sheaves of bio electricity are able to successfully attack and eradicate most types of malignant cancer with metastases including, prostate, breast, lungs, pancreatic, liver, brain, etc. The healthy cells are simultaneously strengthened without any negative side effects. Utilizing the K-BTE medical laser device we release sheaves of laser beams of elementary biological electricity consisting of enriched bio electron's photons sent through biological and mineral agents such as gold, silver and pyrite Fe2. We also send this biological electricity through liquid natural acids, virgin olive oil, fig, and lemon acid, etc. converts these liquid acids (

レーザ装置の承認審査における課題

レーザ装置の承認審査における課題

Definition of K-BTE Medical Laser Device

Definition of K-BTE Medical Laser Device

Accurate Quantification of the Optical Absorption Coefficient and of the Thermal Relaxation Time for PMMA and for Low-Water-Content Media During Early Ablation with CO2Laser Beam at the Wavelength of 10.6 μm

This article describes a new mathematical approach for a more accurate identification of the optical absorption α (per centimeter) and the thermal relaxation time τr (seconds) of dry poly(methyl-methacrylate; PMMA) at λ = 10.6 μm. The data available in the literature do not accurately describe the numeric value of α (per centimeter) for PMMA and other biologic media. The relaxation time, the surface threshold time, and the heat incubation time are all reported on Literature in rather inaccurate fashion. Several well-polished PMMA blocks (1 × 4 × 4 cm) were perpendicularly exposed to focused CW radiation of CO2 medical laser devices showing a TEM22 mode. The exposure was kept constant at 10-W CW. A theoretic focal length of 0.5 inches has been extrapolated to better study the most relevant threshold conditions for ablation on PMMA. Values of α = 536.9 per centimeter and τr = 818 μsec for the PMMA at 10.6 μm were identified. With a similar approach, the same parameters were determined for low-water-content tissues, along with other key thermodynamic coefficients, such as the energy threshold of ablation. The starting radial speed of ablation of the "horizon" of the crater was found to be equal to 0.57 cm/sec, with a threshold average power density for ablation equal to 11.5 W/cm in CW mode. The computerized diagnostic CT(2) tool proposed by the same author has been also extended to include these preliminary results.

Computerized Thermal Characterization Tool (CT)2for Complete Thermodynamic Coefficients Mapping at the Wavelength of 10.6 μm: a PMMA Case Report

This paper details a proposed clinical identification tool, the Computerized Thermal Characterization Tool or (CT)(2), designed to precisely quantify and forecast the ablation capabilities of a CO(2) laser beam and to optimize its usage when human tissue is exposed to 10.6 microm wavelength radiation. As seen in other studies by the same author, the correct identification of the optical absorption of polymethylmethacrylate (PMMA) allows isolating other key time-dependent coefficients, all described qualitatively rather than quantitatively in the literature, with better accuracy. Tests on other biological media were performed and reported as potential contribution for minimally invasive surgical procedures. The laser in use was configured in different combinations amongst the following parameters: transverse electromagnetic modes (TEM(22)), output power, exposure times, and focal lengths. Several PMMA blocks (1 cm x 4 cm x 4 cm) were exposed to the continuous wave radiation of three commercially available CO(2) medical laser devices with a TEM(11) beam profile. The data were used in a computerized simulation to test a priori the thermal behavior of biological media exposed to a CO(2) laser beam. Interestingly, this behavior could be reproduced on a variety of biological and nonbiological media. Threshold injury conditions were reached for the myocardium at 786 W/cm(2) per pulse, for the aorta at 519 W/cm(2) per pulse, and for the PMMA samples at 393 W/cm(2) per pulse. These values can be used as reference for both minimally invasive surgery and for transmyocardial laser revascularization protocols, combined with the proposed (CT)(2). Further investigations are needed to completely validate the potential clinical utilization.

Optical Absorption Coefficient, Time of Thermal Relaxation, Time of Surface Threshold, and Time of Heat Incubation for PMMA Samples at the CO2Laser-Beam Wavelength of 10.6 µm

This paper discusses in detail the mathematical identification of the optical absorption alpha (cm(1)) of Beer's law, a crucial parameter to study the development of laser beam craters into dry poly(methyl methacrylate) (PMMA) samples exposed to steady CO(2) laser beams emitting radiation at lambda = 10.6 microm in continuous- wave (CW) mode. Three additional time-dependent coefficients have been determined as well. In clinical applications, these results are important in order to precisely quantify and forecast the ablation capabilities of the CO(2) laser beam, to optimize its usage in the operating room, and to address the safety issues related to surgical interventions on human tissue. Currently, the data available in the literature do not allow the identification of the numerical value of alpha (cm(1)) for PMMA at lambda = 10.6 microm with enough, and therefore satisfactory, accuracy. Additionally, the correct identification of the optical absorption of PMMA would allow the isolation, with better accuracy, of other key time-dependent coefficients, such as relaxation time, surface threshold time, and heat incubation time, which are all described in the literature in a qualitative rather than quantitative fashion. Correct bone cement preparation depends on the value of alpha (cm(1)) of the PMMA in order to avoid unwanted complications in patients during cement removal via laser techniques. The laser in use was configured in different combinations with the following parameters: transverse electromagnetic modes (TEMnm), output power (I0), exposure times (te), and focal lengths (fk). Several PMMA blocks (1 cm x 4 cm x 4 cm) were exposed to CW radiation of three commercially available CO(2) medical laser devices showing a TEM11 mode. Each block was exposed to the beam on a horizontal and well-polished surface of each sample. Four focal lengths (2.5", 5", 7.5", and 15.75" [400 mm]) were used to focus the beam on the well-polished and dry surface of the PMMA samples. The resulting dimensions of the craters were measured after each exposure, which has been kept at a 10-Watt CW beam. Exposure time ranged from 0.5 to 2 sec. The value of alpha = 502 (cm(1)) for PMMAat 10.6 microm was identified, matching other results reported in the literature for similar compact media in the absence of water content, such as PMMA. The time of thermal relaxation was 9.358 x 10(4) sec, the time of surface threshold was 9.365 x 10(4) sec, and the time of heat incubation was 3.6 x 10(7) sec (all three for PMMAat 10.6 microm for any exposure). Using the calculated value of alpha, one of the practical clinical recommendations would be, for instance, to reduce or to abolish the utilization of colorant dopants in the preparation of the bone cement mixture and therefore reduce the danger of bone damage possible during the removal of bone cement via laser techniques. Other examples refer to other clinical bone and dental treatments.

Metrological Support of Medical Laser Devices

Metrological Support of Medical Laser Devices

Burns caused by medical therapy.

A burn injury may occur as an unexpected consequence of medical treatment. We examined the burn prevention implications of injuries received in a medical treatment facility or as a direct result of medical care. The records of 4510 consecutive admissions to 1 burn center between January 1978 and July 1997 were retrospectively reviewed. A cohort of 54 patients burned as a result of medical therapy was identified and stratified by location (home vs medical facility) and by mechanism of injury. Twenty-two patients were burned in a medical treatment facility, including 12 patients who were burned as a result of careless or unsupervised use of tobacco products. Thirty-two patients were burned as a result of home medical therapy, including 9 patients who had scald injuries from vaporizers, 8 patients who were burned by simultaneous use of cigarettes and home nasal oxygen therapy, and 11 patients who were burned by therapeutic application of heat. In contrast to previous studies, no patient was burned by the use of medical laser devices. To further decrease burn risk from medical therapy we advocate the prohibition of cigarette smoking in any medical facility. Continued tobacco use may represent a contraindication to home oxygen therapy. Given the lack of proof of efficacy combined with the potential for burn injury, the use of vaporizers to treat upper respiratory symptoms should be discouraged. Patients with diminished sensation or altered mental status are at increased risk of burn injury from bathing or topical heat application and merit closer monitoring during these activities.

Medical Applications of Fiber-Based Optical Power Delivery.

This paper reviews the current status of fiber-based optical power delivery for medicine and its applications to minimally invasive therapeutics and diagnostics. Quartz glass fibers, hollow fibers, and infrared glass/crystalline fibers are used for the power transmission of medical lasers. The characteristics of these fibers and fiber-based medical laser devices are described. For clinical applications, fibers are used in combinationwith catheters, endoscopes, or cannulas. Catheter-based applications include laser angioplasty, laser thrombolysis, and PTMR (Percutaneous Trans-Myocardial Revascularization). The endoscope allows the delivery of optical power not only for coagulation but also for tissue removal (ablation). Endoscopes for PDT (PhotoDynamic Therapy) are also developed. For cannula-based applications, PLDD (Percutaneous Laser Disk Decompression), ILCP (Interstitial Laser Coagulation of Prostate), and TUBAL-T (TransUrethral Balloon Thermotherapy) are described. For use in fiber-based optical biopsies, the principle and apparatus of a fluorescence imagingsystem for early cancer detection and an OCT (Optical Coherence Tomography) are introduced.