Cutting and coagulation during intraoral soft tissue surgery using Er: YAG laser.

PubMed

Onisor, I; Pecie, R; Chaskelis, I; Krejci, I

2013-06-01

To find the optimal techniques and parameters that enables Er:YAG laser to be used successfully for small intraoral soft tissue interventions, in respect to its cutting and coagulation abilities. In vitro pre-tests: 4 different Er:YAG laser units and one CO2 unit as the control were used for incision and coagulation on porcine lower jaws and optimal parameters were established for each type of intervention and each laser unit: energy, frequency, type, pulse duration and distance. 3 different types of intervention using Er:YAG units are presented: crown lengthening, gingivoplasty and maxillary labial frenectomy with parameters found in the in vitro pre-tests. The results showed a great decrease of the EMG activity of masseter and anterior temporalis muscles. Moreover, the height and width of the chewing cycles in the frontal plane increased after therapy. Er:YAG is able to provide good cutting and coagulation effects on soft tissues. Specific parameters have to be defined for each laser unit in order to obtain the desired effect. Reduced or absent water spray, defocused light beam, local anaesthesia and the most effective use of long pulses are methods to obtain optimal coagulation and bleeding control.

Comparison of a novel high-power blue diode laser (λ=442 nm) with Ho:YAG (λ=2100 nm), Tm fiber (λ=1940 nm), and KTP (λ=532 nm) lasers for soft tissue ablation

NASA Astrophysics Data System (ADS)

Vinnichenko, Victoriya; Kovalenko, Anastasiya; Arkhipova, Valeriya; Yaroslavsky, Ilya; Altshuler, Gregory; Gapontsev, Valentin

2018-02-01

Three lasers were directly compared, including the Ho:YAG laser (λ = 2100 nm), Tm fiber laser (λ = 1940 nm) operating in 3 different modes (CW, regular pulse, and super pulse), and blue diode laser (λ = 442 nm) for vaporization and coagulation efficiency for treating blood-rich soft tissues, ex vivo, in a porcine kidney model at quasi-contact cutting in water. In addition, experimental results were compared with published data on performance of KTP laser (λ = 532 nm) at similar experimental settings (Power = 60 W and cutting speed = 2 mm/s). Tm fiber laser in pulsed mode and blue laser produced highest vaporization rates of 3.7 and 3.4 mm3/s, respectively. Tm fiber laser (in both CW and pulsed modes) also produced the largest coagulation zone among the laser sources tested. A carbonization zone was observed for Tm fiber laser in CW and pulsed modes, as well as for the blue diode laser. Tm fiber laser in super-pulse mode and Ho:YAG laser both resulted in irregular coagulation zones without carbonization. Comparison with known data for KTP laser revealed that tissue effects of the blue laser are similar to that of the KTP laser. These results suggest that the combination of the two lasers (Tm fiber and blue diode) in one system may achieve high cutting efficiency and optimal coagulation for hemostasis during surgical treatment. Ex vivo testing of the combined system revealed feasibility of this approach. The combination of the CW Tm fiber laser (120W) and the blue diode laser (60W) emitting through a combination tip were compared with CW 120 W Tm fiber laser alone and 120 W Ho:YAG laser. Vaporization rates measured 34, 28, and 6 mm3/s, and coagulation zones measured 0.6, 1.3, and 1.7 mm, respectively. A carbonization zone was only observed with CW Tm fiber laser. The vaporization rate of combined CW Tm fiber laser / blue diode laser was comparable to published data for KTP laser for equivalent total power. Thus, high-power blue diode laser, Tm fiber laser, and their combination may provide an alternative to conventional Ho:YAG and KTP lasers for applications in urology and other surgical fields.

Utility of spatial frequency domain imaging (SFDI) and laser speckle imaging (LSI) to non-invasively diagnose burn depth in a porcine model☆

PubMed Central

Burmeister, David M.; Ponticorvo, Adrien; Yang, Bruce; Becerra, Sandra C.; Choi, Bernard; Durkin, Anthony J.; Christy, Robert J.

2015-01-01

Surgical intervention of second degree burns is often delayed because of the difficulty in visual diagnosis, which increases the risk of scarring and infection. Non-invasive metrics have shown promise in accurately assessing burn depth. Here, we examine the use of spatial frequency domain imaging (SFDI) and laser speckle imaging (LSI) for predicting burn depth. Contact burn wounds of increasing severity were created on the dorsum of a Yorkshire pig, and wounds were imaged with SFDI/LSI starting immediately after-burn and then daily for the next 4 days. In addition, on each day the burn wounds were biopsied for histological analysis of burn depth, defined by collagen coagulation, apoptosis, and adnexal/vascular necrosis. Histological results show that collagen coagulation progressed from day 0 to day 1, and then stabilized. Results of burn wound imaging using non-invasive techniques were able to produce metrics that correlate to different predictors of burn depth. Collagen coagulation and apoptosis correlated with SFDI scattering coefficient parameter ( μs′) and adnexal/vascular necrosis on the day of burn correlated with blood flow determined by LSI. Therefore, incorporation of SFDI scattering coefficient and blood flow determined by LSI may provide an algorithm for accurate assessment of the severity of burn wounds in real time. PMID:26138371

[Chemotherapy in combination with laser coagulation or interstitial hyperthermia--effective combined therapy for disseminated skin melanoma].

PubMed

Akimov, M A; Gel'fond, M L; Gershanovich, M L; Barchuk, A S

2003-01-01

Thirty-eight patients with disseminated skin melanoma received chemotherapy in conjunction with laser coagulation or interstitial hyperthermia of intra- or subcutaneous metastases. Use of combination therapy was followed by a rise to 37% in total response and 16%--complete regression, respectively. Most effectiveness was attained when the dacarbazine + cisplatin + BCNU + tamoxifen regime was employed. In this group of 16 patients (46%), total response was 56% and, what is most significant, 31% in complete regression. In all cases of apparent response, polychemotherapy was administered both before and after laser coagulation or interstitial hyperthermia.

Laser photocoagulation - eye

MedlinePlus

Laser coagulation; Laser eye surgery; Photocoagulation; Laser photocoagulation - diabetic eye disease; Laser photocoagulation - diabetic retinopathy; Focal photocoagulation; Scatter (or pan retinal) photocoagulation; Proliferative ...

Potassium-titanyl-phosphate laser vaporization of the prostate: a comparative functional and pathologic study in canines.

PubMed

Kuntzman, R S; Malek, R S; Barrett, D M; Bostwick, D G

1996-10-01

We compared the functional and pathologic results of potassium-titanyl-phosphate (KTP) laser vaporization prostatectomy with those of neodymium:yttrium-aluminum-garnet (Nd:YAG) laser vaporization and coagulation prostatectomy in dogs. The prostates of 41 dogs were treated with KTP laser vaporization (n = 21), Nd:YAG laser vaporization (n = 10), or Nd:YAG laser coagulation (n = 10). Dogs were sacrificed 2 days or 8 weeks after treatment. Prostates were weighed, measured, serially sectioned, and whole-mounted for histologic analysis. All techniques were hemostatic, and no irrigant absorption was detected. KTP laser vaporization produced a prostatic defect with a mean diameter of 3.0 and 2.4 cm at 2 days and 8 weeks postoperatively, respectively. Smaller defects (P < 0.0005 at 2 days and P < 0.02 at 8 weeks) were produced by Nd:YAG laser vaporization (2.0 and 1.4 cm, respectively) and coagulation (0.5 and 0.9 cm, respectively). No dog treated with KTP laser vaporization was incontinent or developed urinary retention, including 5 dogs whose urethral catheters were removed within 24 hours of surgery. KTP laser vaporization prostatectomy not only provides hemostasis similar to that obtained with Nd:YAG laser coagulation, but also removes tissue at the time of operation, allowing dogs to void without straining within 24 hours of treatment. In addition, the procedure is technically simple, and the operator has excellent control over exactly which tissue is removed and which is left intact. These findings suggest that KTP laser vaporization may be useful in the treatment of human benign prostatic hyperplasia.

Diode laser prostatectomy (VLAP): initial canine evaluation

NASA Astrophysics Data System (ADS)

Kopchok, George E.; Verbin, Chris; Ayres, Bruce; Peng, Shi-Kaung; White, Rodney A.

1995-05-01

This study evaluated the acute and chronic effects of diode laser (960 nm) prostatectomy using a Prolase II fiber in a canine model (n equals 5). The laser fiber consists of a 1000 um quartz fiber which reflects a cone of laser energy, at 45 degree(s) to the axis of the fiber, into the prostatic urethra (Visual Laser Ablation of Prostate). Perineal access was used to guide a 15.5 Fr cystoscope to the level of the prostate. Under visual guidance and continual saline irrigation, 60 watts of laser power was delivered for 60 seconds at 3, 9, and 12 o'clock and 30 seconds at the 6 o'clock (posterior) positions for a total energy fluence of 12,600 J. One prostate received an additional 60 second exposure at 3 and 9 o'clock for a total fluence of 19,800 J. The prostates were evaluated at one day (n equals 1) and 8 weeks (n equals 4). The histopathology of laser effects at one day show areas of necrosis with loss of glandular structures and stromal edema. Surrounding this area was a zone of degenerative glandular structures extending up to 17.5 mm (cross sectional diameter). The histopathology of the 8 week laser treated animals demonstrated dilated prostatic urethras with maximum cross- sectional diameter of 23.4 mm (mean equals 18.5 +/- 3.9 mm). This study demonstrates the effectiveness of diode laser energy for prostatic tissue coagulation and eventual sloughing. The results also demonstrate the safety of diode laser energy, with similar tissue response as seen with Nd:YAG laser, for laser prostatectomy.

Application of CO laser for laser balloon angioplasty

NASA Astrophysics Data System (ADS)

Miyamoto, Akira; Sakurada, Masami; Mizuno, Kyoichi; Kurita, Akira; Nakamura, Haruo; Suda, Akira; Arai, Tsunenori; Kikuchi, Makoto

1990-07-01

CO laser may be efficient for thermal fusion of intima of arterial wall without adventitial tissue damage because of high tissue absorption. To investigate the efficacy of CO laser as a laser bam for laser balloon angioplasty (LBA). CO laser was irradiated to aortic tissue through 3Oim polyethylene membrane and tissue temperature was measured by a thermistor. At 2Owatt/cm2 200joules/cm2 continuous laser exposure (CE), tissue temperature was above 100°C within a depth of 1mm and rapidly decreased to 60 °C or below between 2 and 3mm in depth. Moreover, adventitial temperature could be decreased by changing duty ratio (exposure duration/interval) of intermittent laser exposure (IE) despite of the same laser energy. Light microscopy showed high degree of medial coagulation necrosis in CE, however thermal coagulation was observed only at the surface of intima of aortic tissue in IE at duty ratio 1 / 2. These findings suggested CO laser could coagulate intimal layer with less deep thermal damage compared to Nd- YAG laser and that IE was better for superficial welding than CE at the same energy. We concluded that CO laser might be more efficient as a laser beam for LBA than Nd-YAG laser.

Thermal distribution in biological tissue at laser induced fluorescence and photodynamic therapy

NASA Astrophysics Data System (ADS)

Krasnikov, I. V.; Seteikin, A. Yu.; Drakaki, E.; Makropoulou, M.

2012-03-01

Laser induced fluorescence spectroscopy and photodynamic therapy (PDT) are techniques currently introduced in clinical applications for visualization and local destruction of malignant tumours as well as premalignant lesions. During the laser irradiation of tissues for the diagnostic and therapeutic purposes, the absorbed optical energy generates heat, although the power density of the treatment light for surface illumination is normally low enough not to cause any significantly increased tissue temperature. In this work we tried to evaluate the utility of Monte Carlo modeling for simulating the temperature fields and the dynamics of heat conduction into the skin tissue under several laser irradiation conditions with both a pulsed UV laser and a continuous wave visible laser beam. The analysis of the results showed that heat is not localized on the surface, but it is collected inside the tissue. By varying the boundary conditions on the surface and the type of the laser radiation (continuous or pulsed) we can reach higher than normal temperature inside the tissue without simultaneous formation of thermally damaged tissue (e.g. coagulation or necrosis zone).

Patterned retinal coagulation with a scanning laser

NASA Astrophysics Data System (ADS)

Palanker, Daniel; Jain, ATul; Paulus, Yannis; Andersen, Dan; Blumenkranz, Mark S.

2007-02-01

Pan-retinal photocoagulation in patients with diabetic retinopathy typically involves application of more than 1000 laser spots; often resulting in physician fatigue and patient discomfort. We present a semi-automated patterned scanning laser photocoagulator that rapidly applies predetermined patterns of lesions; thus, greatly improving the comfort, efficiency and precision of the treatment. Patterns selected from a graphical user interface are displayed on the retina with an aiming beam, and treatment can be initiated and interrupted by depressing a foot pedal. To deliver a significant number of burns during the eye's fixation time, each pulse should be considerably shorter than conventional 100ms pulse duration. We measured coagulation thresholds and studied clinical and histological outcomes of the application of laser pulses in the range of 1-200ms in pigmented rabbits. Laser power required for producing ophthalmoscopically visible lesions with a laser spot of 132μm decreased from 360 to 37mW with pulse durations increasing from 1 to 100ms. In the range of 10-100ms clinically and histologically equivalent light burns could be produced. The safe therapeutic range of coagulation (ratio of the laser power required to produce a rupture to that for a light burn) decreased with decreasing pulse duration: from 3.8 at 100ms, to 3.0 at 20ms, to 2.5 at 10ms, and to 1.1 at 1ms. Histology demonstrated increased confinement of the thermal damage with shorter pulses, with coagulation zone limited to the photoreceptor layer at pulses shorter than 10ms. Durations of 10-20ms appear to be a good compromise between the speed and safety of retinal coagulation. Rapid application of multiple lesions greatly improves the speed, precision, and reduces pain in retinal photocoagulation.

Anomalous coagulation factors in non-arteritic anterior ischemic optic neuropathy with central retinal vein occlusion: A case report.

PubMed

Kim, Ji Hong; Kang, Min Ho; Seong, Mincheol; Cho, Heeyoon; Shin, Yong Un

2018-04-01

Non-arteritic anterior ischemic optic neuropathy (NAION) is characterized by sudden, painless visual loss and optic disc edema. NAION occurs mainly in the presence of cardiovascular disease and hypercoagulability, mainly in patients over 50 years of age. We experienced a case of NAION associated with central retinal vein occlusion (CRVO) in a young man with no underlying disease. A 46-year-old man was referred to our clinic following a sudden loss of vision in his right eye. The patient exhibited no underlying disease and reported no ongoing medication. Significant visual loss and visual disturbance of the right eye were observed. The pupil of the right eye was enlarged and an afferent pupillary defect was observed. On fundus examination, retinal hemorrhage was observed in the peripheral retina; macular edema was observed in optical coherence tomography analysis. However, optic disc edema was not evident. No abnormal findings were found in routine blood tests for hypercoagulability. After 3 days of steroid intravenous injection, macular edema disappeared and visual acuity was improved, but optic disc edema began to appear. One week later, optic disc edema was evident and visual acuity was significantly reduced; thus, the patient was diagnosed with NAION. In fluorescein angiography, peripheral retinal ischemia was observed, suggesting that CRVO was complicated. Blood tests, including analysis of coagulation factors, were performed again, showing that coagulation factors IX and XI were increased. Anomalous coagulation factors in non-arteritic anterior ischemic optic neuropathy with central retinal vein occlusion. Systemic steroids were administered. One month later, optic disc edema and retinal hemorrhage gradually diminished and eventually disappeared; however, visual acuity did not recover. In young patients without underlying disease, cases of NAION require careful screening for coagulation disorders. Even if there is no abnormality in the test for routine coagulation status, it may be necessary to confirm a coagulation defect through an additional coagulation factor assay.

Physical analysis on laser-induced cerebral damage

NASA Astrophysics Data System (ADS)

Luo, Xiaosen; Liu, Jiangang; Tao, Chunkan; Lan, Xiufeng; Cao, Lingyan; Pan, Weimin; Shen, Zhonghua; Lu, Jian; Ni, Xiaowu

2005-01-01

Experimental investigation on cerebral damage of adult SD rats induced by 532nm CW laser was performed. Tissue heat conductive equation was set up based on two-layered structure model. Finite difference algorithm was utilized to numerically simulate the temperature distribution in the brain tissue. Allowing for tissue response to temperature variation, free boundary model was used to discuss tissue thermal coagulation formation in brain. Experimental observations show that thermal coagulation and necrosis can be caused due to laser light absorption. The result of the calculation shows that the process of the thermal coagulation of the given mode comprises two stages: fast and slow. At the first stage, necrosis domain grows fast. Then necrosis domain growth becomes slower because of the competition between the heat diffusion into the surrounding undamaged tissue and the heat dissipation caused by blood perfusion. At the center of coagulation area no neuron was observed and at the transitional zone few nervous cells were seen by microscope. The research can provide reference data for developing clinical therapy of some kind of encephalic diseases by using 532nm laser, and for making cerebral infarction models in animal experiment.

Selected applications of Er:YAG and CO2 lasers for treatment of benign neoplasms and tumorous lesions in the mouth.

PubMed

Błochowiak, Katarzyna; Andrysiak, Piotr; Sidorowicz, Krzysztof; Witmanowski, Henryk; Hędzelek, Wiesław; Sokalski, Jerzy

2015-10-01

Benign neoplasms and hyperplastic tumorous lesions are common oral pathologies. These lesions require to be surgically removed by conventional surgery, laser, or electrosurgery. Surgical treatment aims at complete removal of pathological lesions and ensuring proper healing of the tissues to minimize the risk of lesion recurrence. To present possible applications of Er:YAG and CO2 lasers in removal of benign neoplasms and tumorous lesions developing on oral mucosa as well as to specify indications and limitations of these two methods. Temperature-induced injuries due to laser light application, possibility of post-operative histopathological evaluation of the removed tissue, efficacy of the cut and coagulation, healing process and completeness of laser surgeries give rise to our special concern. The main asset of the CO2 laser comparing to Er:YAG laser is an effective coagulation while thermal injury to the tissues is its limitation, especially with multiple passage of the beam and too high power applied. Er:YAG laser application does not exclude histopathological examination of the removed lesion tissue which is its advantage over CO2 laser. Still, insufficient coagulation is a limitation ofits use in the case of richly vascularized lesions.

The effect of CO2 laser treatment on skin tissue.

PubMed

Baleg, Sana Mohammed Anayb; Bidin, Noriah; Suan, Lau Pik; Ahmad, Muhammad Fakarruddin Sidi; Krishnan, Ganesan; Johari, Abd Rahman; Hamid, Asma

2015-09-01

The aim of this study was to evaluate the effects of multiple pulses on the depth of injury caused by CO2 laser in an in vivo rat model. A 10 600-nm CO2 laser was applied to rat skin, with one side of the rat dorsal skin being exposed, leaving the other side as a control. All of the various laser pulses tested led to gradual loss of epidermal thickness as well as a dramatic increase in thermal damage depth. Collagen coagulation was most effective with ten pulses of CO2 laser, while the strength of irradiated skin tissue increased as the influence of the laser increased. Fundamental laser-skin interaction effects were studied using a CO2 laser. The photodamaged areas obtained from laser interaction were recorded via couple charge device video camera and analyzed via ImageJ software. Photodamage induced by CO2 laser is due to photothermal effects, which involve burning and vaporizing mechanisms to ablate the epidermis layer. The burning area literally expands and penetrates deep into the dermis layer, subsequently causing collagen coagulation. This fundamental study shows in detail the effect of CO2 laser interaction with skin. The CO2 attributed severe burning, producing deep coagulation, and induced strength to treated skin. © 2015 Wiley Periodicals, Inc.

Dose control for noncontact laser coagulation of tissue

NASA Astrophysics Data System (ADS)

Roggan, Andre; Albrecht, Hansjoerg; Bocher, Thomas; Rygiel, Reiner; Winter, Harald; Mueller, Gerhard J.

1995-01-01

Nd:YAG lasers emitting at 1064 nm are often used for coagulation of tissue in a non-contact mode, i.e. the treatment of verrucae, endometriosis, tumor coagulation and hemostasis. During this process an uncontrolled temperature rise of the irradiated area leads to vaporization and, finally, to a carbonization of the tissue surface. To prevent this, a dose controlled system was developed using an on-line regulation of the output laser power. The change of the backscattered intensity (remission) of the primary beam was used as a dose dependent feedback parameter. Its dependence on the temperature was determined with a double integrating sphere system and Monte-Carlo simulations. The remission of the tissue was calculated in slab geometry from diffusion theory and Monte-Carlo simulations. The laser control was realized with a PD-circuit and an A/D-converter, enabling the direct connection to the internal bus of the laser system. Preliminary studies with various tissues revealed the practicability of the system.

Past, present, and future of endobronchial laser photoresection

PubMed Central

Khemasuwan, Danai; Wang, Ko-Pen

2015-01-01

Laser photoresection of central airway obstruction is a useful tool for an Interventional Pulmonologist (IP). Endobronchial therapy of the malignant airway obstruction is considered as a palliative measure or a bridge therapy to the definite treatment of cancer. Several ablative therapies such as electrocautery, argon plasma coagulation (APC), cryotherapy and laser photoresection exist in the armamentarium of IP to tackle such presentations. Besides Neodymium-Yttrium, Aluminum, Garnet (Nd:YAG) laser, there are several different types of laser that have been used by the pulmonologist with different coagulative and cutting properties. This chapter focuses on the historical perspective, current status, and potentials of lasers in the management of central airway lesions. PMID:26807285

[Progress in laser neurosurgery].

PubMed

Majchrzak, H; Kopera, M; Idzik, M

1991-01-01

Nd:YAG lasers with different wavelengths are used in neurosurgery. Their great advantage is the ability of coagulation of blood vessels and delivery through flexible fiber optics . Nd:YAG laser with wavelength 1.318 microns is used, besides, to connect blood vessels and nerves. CO2 laser is the best cutting tool but requires, for delivery rigid cable. Both types of lasers cause shrinkage and vaporisation of the tumors what facilitates its removing without greater traumatisation of surrounding tissues. The introduction of sapphire contact tips to Nd:YAG and argon lasers enables application of small laser powers and diminish the area of damage in surrounding structures. Contact laser is used for destroying of tumours, coagulation of blood vessels, restoration of patency of the main arteries, interstitial denaturation of gliomas and denaturation of the nucleus pulposus in lumbar vertebral column.

Quasi-dynamical analysis and real-time tissue temperature monitoring during laser vaporization

NASA Astrophysics Data System (ADS)

Wang, Hui; Ray, Aditi; Jebens, Dave; Chia, Ray; Hasenberg, Tom

2014-03-01

Vaporization and coagulation are two fundamental processes that can be performed during laser-tissue ablation. We demonstrated a method allowing quasi-dynamically observing of the cross-sectional images of tissue response during ablation. The results showed that coagulation depth is relatively constant during vaporization, which supports the excellent hemostasis of green laser benign prostate hyperplasia (BPH) treatment. We also verified a new technology for real-time, in situ tissue temperature monitoring, which may be promising for in vivo tissue vaporization degree feedback during laser ablation to improve the vaporization efficiency and avoid complications.

High power visible diode laser for the treatment of eye diseases by laser coagulation

NASA Astrophysics Data System (ADS)

Heinrich, Arne; Hagen, Clemens; Harlander, Maximilian; Nussbaumer, Bernhard

2015-03-01

We present a high power visible diode laser enabling a low-cost treatment of eye diseases by laser coagulation, including the two leading causes of blindness worldwide (diabetic retinopathy, age-related macular degeneration) as well as retinopathy of prematurely born children, intraocular tumors and retinal detachment. Laser coagulation requires the exposure of the eye to visible laser light and relies on the high absorption of the retina. The need for treatment is constantly increasing, due to the demographic trend, the increasing average life expectancy and medical care demand in developing countries. The World Health Organization reacts to this demand with global programs like the VISION 2020 "The right to sight" and the following Universal Eye Health within their Global Action Plan (2014-2019). One major point is to motivate companies and research institutes to make eye treatment cheaper and easily accessible. Therefore it becomes capital providing the ophthalmology market with cost competitive, simple and reliable technologies. Our laser is based on the direct second harmonic generation of the light emitted from a tapered laser diode and has already shown reliable optical performance. All components are produced in wafer scale processes and the resulting strong economy of scale results in a price competitive laser. In a broader perspective the technology behind our laser has a huge potential in non-medical applications like welding, cutting, marking and finally laser-illuminated projection.

Laser speckle tracking for monitoring and analysis of retinal photocoagulation

NASA Astrophysics Data System (ADS)

Seifert, Eric; Bliedtner, Katharina; Brinkmann, Ralf

2014-02-01

Laser coagulation of the retina is an established treatment for several retinal diseases. The absorbed laser energy and thus the induced thermal damage varies with the transmittance and scattering properties of the anterior eye media and with the pigmentation of the fundus. The temperature plays the most important role in the coagulation process. An established approach to measure a mean retinal temperature rise is optoacoustics, however it provides limited information on the coagulation. Phase sensitive OCT potentially offers a three dimensional temporally resolved temperature distribution but is very sensitive to slightest movements which are clinically hard to avoid. We develop an optical technique able to monitor and quantify thermally and coagulation induced tissue movements (expansions and contractions) and changes in the tissue structure by dynamic laser speckle analysis (LSA) offering a 2D map of the affected area. A frequency doubled Nd:YAG laser (532nm) is used for photocoagulation. Enucleated porcine eyes are used as targets. The spot is 100μm. A Helium Neon laser (HeNe) is used for illumination. The backscattered light of a HeNe is captured with a camera and the speckle pattern is analyzed. A Q-switched Nd:YLF laser is used for simultaneous temperature measurements with the optoacoustic approach. Radial tissue movements in the micrometer regime have been observed. The signals evaluation by optical flow algorithms and generalized differences tuned out to be able to distinguish between regions with and without immediate cell damage. Both approaches have shown a sensitivity of 93% and a specificity above 99% at their optimal threshold.

Prospective study on laser-assisted laparascopic partial nephrectomy

NASA Astrophysics Data System (ADS)

Sroka, Ronald; Hennig, Georg; Zilinberg, Katja; Khoder, Wael Y.

2012-02-01

Introduction: Developments in laparoscopic partial nephrectomy (LPN) opened a demand for surgical tools compatible with laparoscopic manipulations to make laser assisted technique safe, feasible and reproducible. Warm ischemia and bleeding during laparoscopic partial nephrectomy place technical constraints on surgeons. Therefore it was the aim to develop a safe and effective laser assisted partial nephrectomy technique without need for ischemia. Patients and methods: A diode laser emitting light at 1318nm in cw mode was coupled into a bare fibre (core diameter 600 μm) thus able to transfer up to 100W to the tissue. After dry lab experience, a total of 10 patients suffering from kidney malformations underwent laparoscopic/retroperitoneoscopic partial nephrectomy. Clinically, postoperative renal function and serum c-reactive protein (CRP) were monitored. Laser induced coagulation depth and effects on resection margins were evaluated. Demographic, clinical and follow-up data are presented. Using a commercial available fibre guidance instrument for lanringeal intervention, the demands on an innovative laser fibre guidance instrument for the laser assisted laparoscopic partial nephrectomy (LLPN) are summarized. Results: Overall, all laparascopic intervention were succesfull and could be performed without conversion to open surgery. Mean operative time and mean blood loss were comparable to conventional open and laparascopic approaches. Laser assisted resection of the kidney tissue took max 15min. After extirpation of the tumours all patients showed clinical favourable outcome during follow up period. Tumour sizes were measured to be up 5cm in diameter. The depth of the coagulation on the removed tissue ranged between <1 to 2mm without effect on histopathological evaluation of tumours or resection margin. As the surface of the remaining kidney surface was laser assisted coagulated after removal. The sealing of the surface was induced by a slightly larger coagulation margin, but could not measured so far. Based on this experiences a simple and easy to use instrument described serving also for suction and rinsing. Conclusion: This prospective in-vivo feasibility study shows that laser assisted partial nephrectomy seems to be a safe and promising medical technique which could be provided either during open surgery as well as laparascopically. This application showed good haemostasis and minimal parenchymal damage. Further investigations and development are needed for on-line detection of the remain coagulation margin. An optimised treatment equipment will support the applicability of laser assisted laparoscopic partial nephrectomy.

Generation-V dual-Purkinje-image eyetracker

NASA Technical Reports Server (NTRS)

Crane, H. D.; Steele, C. M.

1985-01-01

Major advances characterize the Generation-V dual-Purkinje-image eyetracker compared with the Generation-III version previously described. These advances include a large reduction in size, major improvements in frequency response and noise level, automatic alignment to a subject, and automatic adjustment for different separation between the visual and optic axes, which can vary considerably from subject to subject. In a number of applications described in the paper, the eyetracker is coupled with other highly specialized optical devices. These applications include accurately stabilizing an image on a subject's retina; accurately simulating a visually dead retinal region (i.e., a scotoma) of arbitrary shape, size, and position; and, for clinical purposes, stabilizing the position of a laser coagulator beam on a patient's retina so that the point of contact is unaffected by the patient's own eye movements.

Endoscopic laser-induced steam generator: a new method of treatment for early gastric cancer

NASA Astrophysics Data System (ADS)

Hayashi, Takuya; Arai, Tsunenori; Tajiri, Hisao; Nogami, Yashiroh; Hino, Kunihiko; Kikuchi, Makoto

1996-05-01

The minimum invasive endoscopic treatment for early gastric cancer has been popular in Japan. The endoscopic mucosal resection and laser coagulation by Nd:YAG laser irradiation has been the popular treatment method in this field. However, the submucosal cancer has not been successfully treated by these methods. To treat the submucosal cancer endoscopically, we developed a new coagulation therapy using hot steam generated by Nd:YAG laser. The steam of which temperature was over 10 deg. in Celsius was generated by the laser power of 30 W with 5 ml/min. of saline. The steam was emitted to canine gastric wall under laparotomy or endoscopy for 50 s respectively. Follow up endoscopy was performed on 3, 7, 14, 28 days after the treatment. Histological examination was studied on 7, 28 days, and just after the emission. In the acute observation, the submucosal layer was totally coagulated. On the 7th day, ulceration with white coat was seen. The mucosal defect, submucosal coagulation, and marked edema without muscle degeneration were found by the histological study. On the 14th day, the ulcer advanced in the scar stage. On the 28th day, it completely healed into white scar with mucosal regeneration and mucosal muscle thickening. We could obtain reproducible coagulation up to deep submucosal layer with large area in a short operation time. Moreover there were no degeneration of proper muscle. This treatment effectiveness could be easily controlled by the steam temperature and emission duration. We think that this method can be applied to early gastric cancer including the submucosal cancer, in particular poor risk case for operation. Further study should be done to apply this method to clinical therapy.

Comparison of the effect of the carbon dioxide laser and the bipolar coagulator on the cat brain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cozzens, J.W.; Cerullo, L.J.

The carbon dioxide laser has recently received clinical acceptance in neurosurgical practice. There are, however, few studies reported in the neurosurgical literature, either clinical or experimental, concerning its safety or efficacy on a physiological level by comparison to a more conventional tool. This study is not a description of a surgical technique, but is rather a basic physiological comparison of two surgical instruments. In this study, 11 cats were pretreated with the protein-bound dye, Evans blue. A corticotomy was performed in one hemisphere with the carbon dioxide laser and in the other with a microbipolar coagulator and a sharp blade.more » The subsequent extravasation of dye was presumed to be proportional to the amount of blood-brain barrier disruption associated with each lesion. When effective power settings for the two devices were compared, the laser lesions had significantly less extravasation of blue dye. This indicated that there was less damage to the blood-brain barrier surrounding laser corticotomy than surrounding conventional bipolar coagulation and sharp dissection at comparable power settings for each modality.« less

Invasive leg vein treatment with 1064/1319 Nd:YAG laser: combination with dye laser treatment

NASA Astrophysics Data System (ADS)

Smucler, Roman; Horak, Ladislav; Mazanek, Jiri

1999-06-01

More than 2 500 leg veins patients were treated with dye laser / ScleroPlus, Candela, USA / successfully in our clinic and we use this therapy as the basic cosmetics treatment. But especially diameter of leg vein is limiting factor. Very often we have to treat some cases that are not ideal for classical surgical or for dye laser method. We decided to make invasive perivenous laser coagulation. We adapted original Czech 1064/1319 nm Nd:YAG laser / US patent pending /, which is new combine tool, for invasive application. Principe: After we have penetrated the cutis with laser fiber we coagulate leg veins during slowly perivenous motion. Perfect preoperative examination is a condition of success. After 15 months we have very interesting results. Some patients / 15%/ were perfect treated only with this possibility but excellent results are acquired from combination with dye laser.

Near-infrared fiber delivery systems for interstitial photothermal therapy

NASA Astrophysics Data System (ADS)

Slatkine, Michael; Mead, Douglass S.; Konwitz, Eli; Rosenberg, Zvi

1995-05-01

Interstitial photothermal coagulation has long been recognized as a potential important, minimally invasive modality for treating a variety of pathologic conditions. We present two different technologies for interstitial photothermal coagulation of tissue with infrared lasers: An optical fiber with a radially symmetric diffusing tip for deep coagulation, and a flat bare fiber for the coagulation of thin and long lesions by longitudinally moving the fiber while lasing in concert. Urology and Gynecology Fibers: The fibers are 600 microns diameter with 20 - 40 mm frosted distal tips protected by a smooth transparent cover. When used with a Neodymium:YAG (Nd:YAG) laser, the active fiber surface diffuses optical radiation in a radial pattern, delivering up to 40 W power, and thus providing consistent and uniform interstitial photothermal therapy. Coagulation depth ranges from 4 to 15 mm. Animal studies in the United States and clinical studies in Europe have demonstrated the feasibility of using these fibers to treat benign prostatic hyperplasia and endometrial coagulation. Rhinology Fiber: The fiber is an 800 micron diameter flat fiber operated at 8 W power level while being interstitially pushed and pulled along its axis. A long and thin coagulated zone is produced. The fiber is routinely used for the shrinking of hypertrophic turbinates without surrounding and bone mucusal damage in ambulatory environments.

Thoracoscopic CO laser coagulation shrinkage of blebs in treatment of spontaneous pneumothorax

NASA Astrophysics Data System (ADS)

Sensaki, Koji; Arai, Tsunenori; Kikuchi, Keiichi; Takagi, Keigo; Tanaka, Susumu; Kikuchi, Makoto

1992-06-01

Spontaneous pneumothorax is a common disease in young people. Operative intervention has been done in most of the recurrent cases. Recently thoracoscopic treatment has been tested as a less invasive treatment modarity. We adopted carbon monoxide (CO) laser for thoracoscopic treatment of recurrent spontaneous pneumothorax. CO laser (wavelength; 5.4 micrometers ) could be delivered by chalcogenide glass (As - S) covered with a teflon sheath and ZnSe fiber tip. The sterilized flexible bronchoscope was inserted through the thoracoscopic outer sheath under local anesthesia. Shrinkage of blebs was obtained by non-contact method of CO laser irradiation. Laser power at the tip was 2.5 - 5 W and irradiation duration was 0.5 s each. Excellent shrinkage of bleb and bulla could be obtained by CO laser without perforation complication. Advantages of CO laser as a thoracoscopic treatment were: (1) capability of fiber delivery (flexible thoracoscopy was easy to operate and clear to visualize the blebs which were frequently found at the apical portion of the lung, and (2) shallow extinction length (good shrinkage of blebs, low risk of perforation, and thin layer of carbonization). In conclusion, our new technique of thoracoscopic CO laser irradiation was found to be a safe and effective treatment of spontaneous pneumothorax.

Laser prostatectomy with side-firing Albarran bridge

NASA Astrophysics Data System (ADS)

Mattioli, Stefano

1996-01-01

Laser ablation of the prostatic tissue or laser prostatectomy, is used as an alternative method to traditional endoscopic resection of the prostate (TURP). Recently, there have been reports of transurethral coagulation of the prostate using various sidefiring laser systems. These devices can be classified into two groups: one that uses total internal reflection, and one that has a gold-plated metal reflecting mirror. We have developed a new Albarran bridge with these characteristics in order to minimize the restrictions presented by the other delivery systems. Laser coagulation of the prostate has been performed using a conventional bare fiber passed through a sidefiring Albarran bridge containing a distal gold-plated reflector with a deflecting mechanism. The complete device passes through a 21 F. rigid cystourethroscope. The system and the fiber can be used for several dozen treatments. Transurethral laser coagulation was performed on 65 patients for obstructive symptoms caused by begnin prostatic hyperplasia. The dosimetry was 1000 J per 1cc of prostatic tissue at 60 W for 60 seconds. Successful results were obtained in 55 patients (85%). A significant reduction in obstructive symptoms from a mean AUA-6 Symptom Score of 21.2 preoperatively to 9.1 at 3 months and 7.6 at 6 months was associated with an increase in the peak urine flow rate from 6.1 mL/sec preoperatively to 13.1 mL/sec at 3 months and 15.7 mL/sec at 6 months. The residual urine volume averaged 190 mL preoperatively and 365 mL at 6 months. Transurethral laser coagulation of the prostate represents a useful alternative to transurethral resection, especially in high-risk patients with an enlarged median lobe or a small prostate. Treatment is bloodless and, with the aid of the modified Albarran bridge, can be performed with standard urological instrumentation and conventional Nd:YAG laser system. The new Albarran bridge also can reduce the cost of laser treatment.

Ex vivo evaluation of safety and efficacy of vaporization of the prostate using a 300 W high-power laser diode with the wavelength of 980 nm

NASA Astrophysics Data System (ADS)

Takada, Junya; Honda, Norihiro; Hazama, Hisanao; Awazu, Kunio

2014-03-01

Laser vaporization of the prostate is one of the promising technique for less-invasive treatment of benign prostatic hyperplasia. However, shorter operative duration and higher hemostatic ability are expected. The wavelength of 980 nm offers a high simultaneous absorption by water and hemoglobin, so that it combines the efficient vaporization with good hemostasis. Therefore, we have evaluated the safety and efficacy of vaporization of the prostate using a recently developed 300 W high-power laser diode with the wavelength of 980 nm. First, validity of bovine prostate tissue as the sample was confirmed by measuring the optical properties of bovine and human prostate tissue using a double integrating sphere optical system. Next, contact and non-contact ex vivo irradiations were performed for various irradiation powers and times, and vaporized and coagulated depths were measured. In the contact irradiation, the vaporized depth at the power of 300 W was significantly deeper than that at the power of 100 W, while the difference was relatively smaller for the coagulated depths at 300 and 100 W. In the non-contact irradiation, coagulation as thick as that in the contact irradiation was observed almost without vaporization. Therefore, it is suggested that the treatment in the contact irradiation using the high-power laser diode can vaporize the prostate more efficiently without increasing the risk of perforation. Hemostasis with the coagulation would be possible in both irradiation methods. To prevent the postoperative perforation, operators need to understand the relationship between the coagulated depth and the irradiation conditions.

Instrumentation For The Surgical Application Of The Nd:YAG Laser

NASA Astrophysics Data System (ADS)

Frank, F.; Bailer, P.; Beck, O.; Bowering, R.; Hofstetter, A.

1984-03-01

The Nd:YAG laser has become a coagulation instrument, which has found acceptance in interdisciplinary surgery. The main contributors are its highly efficient coagulation capability in interaction with tissue and the fact that the Nd:YAG laser beam can be transmitted by means of a simple quartz-glass fiber. Appropriate systems and instruments for transmission and operation have been developed for the various applications in neurosurgery, pulmology, gastroenterology, urology, gynaecology and dermatology. Operation methods in open and endoscopic surgery under use of several hand held devices and flexible as well as rigid endoscopes are being demonstrated by clinical examples of application.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murase, Kenya, E-mail: murase@sahs.med.osaka-u.ac.jp; Song, Ruixiao; Hiratsuka, Samu

We investigated the feasibility of visualizing blood coagulation using a system for magnetic particle imaging (MPI). A magnetic field-free line is generated using two opposing neodymium magnets and transverse images are reconstructed from the third-harmonic signals received by a gradiometer coil, using the maximum likelihood-expectation maximization algorithm. Our MPI system was used to image the blood coagulation induced by adding CaCl{sub 2} to whole sheep blood mixed with magnetic nanoparticles (MNPs). The “MPI value” was defined as the pixel value of the transverse image reconstructed from the third-harmonic signals. MPI values were significantly smaller for coagulated blood samples than thosemore » without coagulation. We confirmed the rationale of these results by calculating the third-harmonic signals for the measured viscosities of samples, with an assumption that the magnetization and particle size distribution of MNPs obey the Langevin equation and log-normal distribution, respectively. We concluded that MPI can be useful for visualizing blood coagulation.« less

Effects of Nd:YAG and CO2 lasers on cerebral microvasculature. Study in normal rabbit brain.

PubMed

Kuroiwa, T; Tsuyumu, M; Takei, H; Inaba, Y

1986-01-01

The effect of Nd:YAG and CO2 laser beams on cerebral microvasculature was examined in experimental animals. Soft x-ray microangiography and histological examination of the brain after Nd:YAG laser exposure revealed broad avascular or oligovascular zones in the irradiated and the surrounding edematous tissue, in which the surviving vessels were narrowed and tapered without significant leakage of blood. After CO2 laser exposure, a wedge-shaped tissue defect surrounded by layers of charring, coagulation, and edema was observed. The main finding in the surrounding coagulation and edematous layers was dilatation of the vessels. Hemorrhage was sometimes observed, mainly in the edematous layer. These findings seem to explain the effective hemostatic capability of the Nd:YAG laser and the occasional hemorrhage following CO2 laser exposure, especially at high energy output.

Optical coherence tomography vs. high-frequency ultrasound during noninvasive laser coagulation of the canine vas deferens

NASA Astrophysics Data System (ADS)

Cilip, Christopher M.; Allaf, Mohamad E.; Fried, Nathaniel M.

2012-02-01

A noninvasive approach to vasectomy may eliminate male fear of complications related to surgery and increase its acceptance. Noninvasive laser thermal occlusion of the canine vas deferens has recently been reported. In this study, optical coherence tomography (OCT) and high-frequency ultrasound (HFUS) are compared for monitoring laser thermal coagulation of the vas in an acute canine model. Bilateral noninvasive laser coagulation of the vas was performed in 6 dogs (n=12 vasa) using a Ytterbium fiber laser wavelength of 1075 nm, incident power of 9.0 W, pulse duration of 500 ms, pulse rate of 1 Hz, and 3-mm-diameter spot. Cryogen spray cooling was used to prevent skin burns during the procedure. An OCT system with endoscopic probe and a HFUS system with 20-MHz transducer were used to image the vas immediately before and after the procedure. Vasa were then excised and processed for gross and histologic analysis for comparison with OCT and HFUS images. OCT provided high-resolution, superficial imaging of the compressed vas within the vas ring clamp, while HFUS provided deeper imaging of the vas held manually in the scrotal fold. Both OCT and high HFUS are promising imaging modalities for real-time confirmation of vas occlusion during noninvasive laser vasectomy.

Real time speckle monitoring to control retinal photocoagulation

NASA Astrophysics Data System (ADS)

Bliedtner, Katharina; Seifert, Eric; Brinkmann, Ralf

2017-07-01

Photocoagulation is a treatment modality for several retinal diseases. Intra- and inter-individual variations of the retinal absorption as well as ocular transmission and light scattering makes it impossible to achieve a uniform effective exposure with one set of laser parameters. To guarantee a uniform damage throughout the therapy a real-time control is highly requested. Here, an approach to realize a real-time optical feedback using dynamic speckle analysis in-vivo is presented. A 532 nm continuous wave Nd:YAG laser is used for coagulation. During coagulation, speckle dynamics are monitored by a coherent object illumination using a 633 nm diode laser and analyzed by a CMOS camera with a frame rate up to 1 kHz. An algorithm is presented that can discriminate between different categories of retinal pigment epithelial damage ex-vivo in enucleated porcine eyes and that seems to be robust to noise in-vivo. Tissue changes in rabbits during retinal coagulation could be observed for different lesion strengths. This algorithm can run on a FPGA and is able to calculate a feedback value which is correlated to the thermal and coagulation induced tissue motion and thus the achieved damage.

Retinotomy using an erbium:YAG laser on human autopsy eyes

NASA Astrophysics Data System (ADS)

Ellsworth, Lansing G.; Kramer, Theresa R.; Noecker, Robert J.; Snyder, Robert W.; Yarborough, J. Michael

1994-06-01

Mid-IR lasers that operate near the absorption peak of water have a short penetration depth in ocular tissues. Ablation of tissue can be accomplished with minimal coagulative damage to underlying structures. We used an erbium:YAG laser equipped with a contact probe to create retinotomy sites in the human retina of eye bank eyes. An erbium:YAG laser (2.94 micrometers ) equipped with an infrared transmitting glass fiber and a sapphire tip (400 micrometers ) was used to directly ablate the surface of the retina. We administered both single and multiple pulses to the macula and peripheral retina using energy levels from 4 to 16 mJ per pulse. The retinas were then examined histopathologically to evaluate the extent of ablation and coagulative damage. Single pulses at low energy levels were noted to cause ablative damage to the nerve fiber layer and ganglion cell layer without a notable coagulative effect. The mean ablation depth at lower energy levels was less than the mean ablation depth at higher energy levels. Extensive laser application produced disruption of the retinal pigment epithelium, choroid and sclera. the erbium:YAG laser equipped with a contact probe is an effective means of creating retinotomies in human autopsy eyes. When used in the single pulse mode at lower energy levels, the erbium:YAG laser appears capable of removing superficial retinal layers without damaging deeper structures.

Diode laser supported partial nephrectomy in laparoscopic surgery: preliminary results

NASA Astrophysics Data System (ADS)

Sroka, Ronald; Hennig, Georg; Zillinberg, Katja; Khoder, Wael Y.

2011-07-01

Introduction: Warm ischemia and bleeding during laparoscopic partial nephrectomy place technical constraints on surgeons. Therefore it was the aim to develop a safe and effective laser assisted partial nephrectomy technique without need for ischemia. Patients and methods: A diode laser emitting light at 1318nm in cw mode was coupled into a bare fibre (core diameter 600 μm) thus able to transfer up to 100W to the tissue. After dry lab experience, a total of 8 patients suffering from kidney malformations underwent laparoscopic/retroperitoneoscopic partial nephrectomy. Clinically, postoperative renal function and serum c-reactive protein (CRP) were monitored. Laser induced coagulation depth and effects on resection margins were evaluated. Demographic, clinical and follow-up data are presented. Results: Overall interventions, the mean operative time was 116,5 minutes (range 60-175min) with mean blood loss of 238ml (range 50-600ml) while laser assisted resection of the kidney tissue took max 15min. After extirpation of the tumours all patients showed clinical favourable outcome during follow up period. The tumour size was measured to be 1.8 to 5cm. With respect to clinical safety and due to blood loos, two warm ischemia (19 and 24min) must be performed. Immediate postoperative serum creatinine and CRP were elevated within 0.1 to 0.6 mg/dl (mean 0.18 mg/dl) and 2.1-10 mg/dl (mean 6.24 mg/dl), respectively. The depth of the coagulation on the removed tissue ranged between <1 to 2mm without effect on histopathological evaluation of tumours or resection margin. As the surface of the remaining kidney surface was laser assisted coagulated after removal. The sealing of the surface was induced by a slightly larger coagulation margin, but could not measured so far. Conclusion: This prospective in-vivo feasibility study shows that 1318nm-diode laser assisted partial nephrectomy seems to be a safe and promising medical technique which could be provided either during open surgery as well as laparascopically. This application showed good haemostasis and minimal parenchymal damage. Oncological safety appears to be warranted by the use of diode laser. Further investigations and development are needed for on-line detection of the remain coagulation margin, optimisation of the treatment equipment, and finally to train the application technique.

Understanding the tissue interaction of new treatment modalities in laparoscopic surgery in view of safe and effective application (Conference Presentation)

NASA Astrophysics Data System (ADS)

Grimbergen, Matthijs C. M.; Klaessens, John H.; van der Veen, Albert J.; Verdaasdonk, Rudolf M.

2016-03-01

During laparoscopic surgery, devices are require to either cut, ablate or coagulate tissue and veins with high precision and controlled lateral damage preferably in an one-for-all modality. The tissue interactions of 3 new treatment modalities were studied using special imaging techniques to obtain a better understanding the working mechanism in view of effective and safe application. The Plasmajet produces a high temperature ionized gas 'flame' directed to the tissue surface at the tip of a 4 mm diameter rigid hand piece. The Lumenis DUO CO2 laser enables endoscopic laser energy delivery through a 1 mm outer diameter flexible hollow waveguide. The 2 µm 'Thulium' laser is delivered by (standard) 400 µm diameter optical fiber. Thermal imaging and Schlieren techniques were used to assess the superficial ablative and coagulation effects these surgical instruments scanning at preset velocities and distances from the surface of biological tissues and phantoms . The CO2 was very effective in tissue ablation even at a distance up to 10 mm due to a very small diverging beam from the hollow waveguide. In contrast, the Thulium laser showed less ablation and increasing coagulation at larger distance to the tissue. The gas 'flame' of the Plasmajet spread the thermal energy over the surface for effective superficial ablation and coagulation. However, the pressure of the gas flow is substantial on the tissue surface creating turbulence and even indirect cooling. The specific ablation and coagulation effects of the three treatment modalities have to be appreciate and the effective and safe application will depend on the preference and skills of the surgeon

Feasibility of laser-integrated high intensity focused ultrasound (HIFU) treatment for bladder tumors: in vitro study (Conference Presentation)

NASA Astrophysics Data System (ADS)

Nguyen, Van Phuc; Park, Suhyun; Oh, Junghwan; Kang, Hyun Wook

2016-02-01

Previous studies have shown that photothemal therapy combined with high intensity focused ultrasound (HIFU) can provide a promising method to achieve rapid thermal coagulation during surgical procedures. The current study investigated the feasibility of the laser-integrated high intensity focused ultrasound (HIFU) application to treat bladder tumors by enhancing thermal effects and therapeutic depth in vitro. To generate thermal coagulation, a single element HIFU transducer with a central frequency of 2.0 MHz was used to transmit acoustic energy to 15 fresh porcine bladders injected with an artificial tumor (100 µl gelatin and hemoglobin solution) in vitro. Simultaneously, an 80-W 532-nm laser system was also implemented to induce thermal necrosis in the targeted tissue. The intensity of 570 W/cm2 at the focus of HIFU and laser energy of 0.9 W were applied to all the samples for 40 s. The temperature rise increased up to about 1.6 or 3 folds (i.e., ΔT=32±3.8 K for laser-integrated HIFU, ΔT=20±6.5 K for HIFU only, and ΔT=11±5.6 K for laser only). The estimated lesion depth also increased by 1.3 and 2 folds during the dual-thermal treatment, in comparison with the treatment by either HIFU or laser. The results indicated that the laser-integrated HIFU treatment can be an efficient hyperthermic method for tumor coagulation.

Pathogen Reduction in Human Plasma Using an Ultrashort Pulsed Laser

PubMed Central

Tsen, Shaw-Wei D.; Kingsley, David H.; Kibler, Karen; Jacobs, Bert; Sizemore, Sara; Vaiana, Sara M.; Anderson, Jeanne; Tsen, Kong-Thon; Achilefu, Samuel

2014-01-01

Pathogen reduction is a viable approach to ensure the continued safety of the blood supply against emerging pathogens. However, the currently licensed pathogen reduction techniques are ineffective against non-enveloped viruses such as hepatitis A virus, and they introduce chemicals with concerns of side effects which prevent their widespread use. In this report, we demonstrate the inactivation of both enveloped and non-enveloped viruses in human plasma using a novel chemical-free method, a visible ultrashort pulsed laser. We found that laser treatment resulted in 2-log, 1-log, and 3-log reductions in human immunodeficiency virus, hepatitis A virus, and murine cytomegalovirus in human plasma, respectively. Laser-treated plasma showed ≥70% retention for most coagulation factors tested. Furthermore, laser treatment did not alter the structure of a model coagulation factor, fibrinogen. Ultrashort pulsed lasers are a promising new method for chemical-free, broad-spectrum pathogen reduction in human plasma. PMID:25372037

Analysis of Depth of Ablation,Thermal Damage, Wound Healing, and Wound Contraction With Erbium YAG Laser in a Yorkshire Pig Model.

PubMed

Alsaad, Salman M S; Ross, E Victor; Smith, Wiley J; DeRienzo, Damian P

2015-11-01

The erbium YAG laser is commonly used for skin resurfacing. It is known that varying the pulse duration can influence residual thermal damage and wound healing. Our study used a porcine model to evaluate a broad range of settings in a comparison of depth of ablation, depth of residual thermal damage (RTD), and wound contraction employing both a full coverage and fractional hand piece with an erbium YAG laser. The laser delivered an ablative pulse followed by a heating pulse of variable duration using either the full coverage or fractional hand piece. Pulse durations for specific coagulation depths were selected based on existing heat transfer models. The bilateral flanks of a single Yorkshire pig were irradiated. There were 14 treatment groups. 3 sites were treated per group for a total of 42 sites. Two of the 3 sites were for observational assessments and the 3rd site served as a reservoir for biopsies. Biopsy specimens were collected on days 0, 1, 3, 7, 14, and 28. Bleeding, erythema, wound healing, and wound contraction (in the fractional hand piece groups) were assessed. Wound healing is faster for fractional laser skin resurfacing compared with traditional contiguous resurfacing as demonstrated by textural changes and degree of erythema. The laser operator can be confident that the depth of ablation displayed on this system accurately reflects what is occurring in vivo for both confluent and fractional modes. Likewise, the measured degree of coagulation was consistent with panel display settings for the confluent mode. However, the degree of coagulation, as measured by the thickness of residual thermal damage, did not vary significantly between the fractional groups. In other words, the pulse duration of the second (heating) pulse did not impact the degree of coagulation in the fractional mode. There was a 2.3% wound contraction between some groups and a 6.5% wound contraction between other groups. A two way analysis of variance found a statistically significant difference in wound contraction based on ablation depth ( P = 0.012) but the degree of coagulation did not prove to be statistically significant for wound contraction (P = 0.66).

The hemorrhoid laser procedure technique vs rubber band ligation: a randomized trial comparing 2 mini-invasive treatments for second- and third-degree hemorrhoids.

PubMed

Giamundo, Paolo; Salfi, Raffaele; Geraci, Maria; Tibaldi, Livio; Murru, Luisa; Valente, Marco

2011-06-01

Hemorrhoid laser procedure is a new laser procedure for outpatient treatment of hemorrhoids in which hemorrhoidal arterial flow feeding the hemorrhoidal plexus is stopped by means of Doppler-guided laser coagulation. Our aim was to compare the hemorrhoid laser procedure with rubber band ligation for outpatient treatment of symptomatic hemorrhoids with moderate mucosal prolapse. This was a randomized controlled trial with balanced allocation to hemorrhoid laser procedure or rubber band ligation, with stratification by study center. This study was conducted at 2 teaching hospitals in Italy. Patients with symptomatic grade II or grade III hemorrhoids with minimal mucosal prolapse were eligible for the study. In the hemorrhoid laser procedure operation, a Doppler probe was inserted into the anal canal through a dedicated disposable proctoscope to identify the terminal branches of superior hemorrhoidal arteries approximately 3 cm above the dentate line. Five pulsed laser shots were delivered to each identified artery through the proctoscope to close the terminal branches. The procedure was repeated for each artery through clockwise rotation of the proctoscope. Absence of a Doppler signal after treatment confirmed arterial coagulation. Rubber band ligation was performed by positioning rubber bands at the base of left lateral, right anterior, and right posterior piles. No anesthesia was given for either technique. Operative time, complications, postoperative pain (visual analog scale), postoperative downgrading of hemorrhoids, resolution of symptoms, and quality of life were evaluated. A total of 60 patients (35 women, 25 men; mean age, 46 years) entered the trial and were analyzed. No significant differences between rubber band ligation and hemorrhoid laser procedure were observed in operative time or intraoperative morbidity. The median postoperative pain score was 2.9 (range, 1-5) with rubber band ligation vs 1.1 (range, 0-2) for hemorrhoid laser procedure (P < .001). At 6 months, resolution of symptoms was observed in 16 patients (53%) with ligation vs 27 (90%) with hemorrhoid laser procedure (P < .001), and reduction of hemorrhoids by at least 1 grade was observed in 12 patients (40%) with ligation vs 24 (80%) with hemorrhoid laser procedure (P < .001). Significantly higher quality of life was seen in the hemorrhoid laser procedure group (P = .002). Follow-up was not longer than 1 year (median, 6 mo). Despite higher cost, the hemorrhoid laser procedure technique was more effective than rubber band ligation in reducing postoperative pain, resolving symptoms, and improving quality of life in patients with grade II or III hemorrhoids with incomplete mucosal prolapse.

21 CFR 886.4390 - Ophthalmic laser.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ophthalmic laser. 886.4390 Section 886.4390 Food... DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4390 Ophthalmic laser. (a) Identification. An ophthalmic laser is an AC-powered device intended to coagulate or cut tissue of the eye, orbit, or surrounding skin...

21 CFR 886.4390 - Ophthalmic laser.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Ophthalmic laser. 886.4390 Section 886.4390 Food... DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4390 Ophthalmic laser. (a) Identification. An ophthalmic laser is an AC-powered device intended to coagulate or cut tissue of the eye, orbit, or surrounding skin...

21 CFR 886.4390 - Ophthalmic laser.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Ophthalmic laser. 886.4390 Section 886.4390 Food... DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4390 Ophthalmic laser. (a) Identification. An ophthalmic laser is an AC-powered device intended to coagulate or cut tissue of the eye, orbit, or surrounding skin...

21 CFR 886.4390 - Ophthalmic laser.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Ophthalmic laser. 886.4390 Section 886.4390 Food... DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4390 Ophthalmic laser. (a) Identification. An ophthalmic laser is an AC-powered device intended to coagulate or cut tissue of the eye, orbit, or surrounding skin...

21 CFR 886.4390 - Ophthalmic laser.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Ophthalmic laser. 886.4390 Section 886.4390 Food... DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4390 Ophthalmic laser. (a) Identification. An ophthalmic laser is an AC-powered device intended to coagulate or cut tissue of the eye, orbit, or surrounding skin...

Impact of holmium fibre laser radiation (λ = 2.1 μm) on the spinal cord dura mater and adipose tissue

DOE Office of Scientific and Technical Information (OSTI.GOV)

Filatova, S A; Kamynin, V A; Ryabova, A V

The impact of holmium fibre laser radiation on the samples of biologic tissues (dura mater of spinal cord and adipose tissue with interlayers of muscle) is studied. The experimental results are evaluated by the size of carbonisation and coagulation necrosis zones. The experiment shows that in the case of irradiation of the spinal cord dura mater samples the size of carbonisation and coagulation necrosis zones is insignificant. In the adipose tissue the carbonisation zone is also insignificant, but the region of cellular structure disturbance is large. In the muscle tissue the situation is opposite. The cw laser operation provides clinicallymore » acceptable degree of destruction in tissue samples with a minimal carbonisation zone. (laser applications in medicine)« less

Histologic effects of a high-repetition pulsed Nd:YAG laser on intraoral soft tissue

NASA Astrophysics Data System (ADS)

White, Joel M.; Goodis, Harold E.; Yessik, Michael J.; Myers, Terry D.

1995-05-01

High-repetition rate, fiberoptic-delivered Nd:YAG lasers have increased oral soft tissue laser applications. This study focused on three parameters: the temperature rise occurring in deeper tissue during excision, the histology of thermal coagulation during excision of oral tissue, and effects of accidental exposure to adjacent hard tissue. Thermocouples were placed 5.0 +/- 0.5 mm in bone below fresh bovine gingiva and at the same depth in tongue; temperatures in the underlying tissue were measured during laser excision. An Nd:YAG laser with 100 microsecond(s) pulse duration was used to excise the tissue using a 200 or 300 micrometers diameter fiber in contact with the tissue. The soft tissue was excised using constant force and rate with laser powers of 1.5, 3, 5, and 10 W, and a variety of pulse rates. The tissue was bioprepared, sectioned and stained with hematoxylin and eosin. The width and depth of the tissue removed as well as lateral and deep thermal coagulation were measured in histologic sections with a measuring microscope (10x). Multifactor randomized ANOVA showed that probe diameter and repetition rates were not significant variables (p

Effects Of Continuous Argon Laser Irradiation On Canine And Autopsied Human Cardiac Tissue

NASA Astrophysics Data System (ADS)

Ben-Shachar, Giora; Sivakoff, Mark; Bernard, Steven L.; Dahms, Beverly B.; Riemenschneider, Thomas A.

1984-10-01

In eight human formalin preserved cardiac specimens, various cardiac and vascular obstructions were relieved by argon laser irradiation. Interatrial communication was also produced by a transar'rial approach in a live dog. In-vivo fresh canine cardiac tissues required power density of at feast 80, 90, and 110 watts/cm2 for vaporization of myocardial, vascular and valvular tissues respectively. The fiber tip to tissue distance (effective irradiation distance) for effective vaporization was less than I mm for vascular and valvular tissues and less than 4 mm for myocardium. Light microscopy showed four zones of histological damage common to all tissues - central crater surrounded by layers of charring, vacuolization and coagulation necorsis. Myocardium showed additionally a layer of normal appearing muscle cells (skip area) surrounded by a peripheral coagulation halo. Laser irradiation effects on valvular tissue showed the most lateral extension of coagulation necrosis. It is concluded that palliation and treatment of certain congenital heart defects by laser irradiation is anatomi-cally feasible and may be safe for in vivo application when low power output and short exposure time are used from a very short irradiation distance.

Evaluation of laser radiation regimes at thermal tissue destruction

NASA Astrophysics Data System (ADS)

Ivanov, Anatoly; Kazaryan, Mishik A.; Molodykh, E. I.; Shchetinkina, T. A.

1996-01-01

The existing methods of laser destruction of biotissues, widely spread in surgery and coagulation action, are based on local heat emission in the tissues after light absorption. Here we present the results of the simulation of tissues heat destruction, taking into account the influence of blood and lymph circulation on the processes of heat transfer. The problem is adapted to the case of liver tissue with tumor. A liver is considered as a capillary-porous body with internal blood circulation. Heatconductivity and tissue-blood heat transfer are considered. Heat action is assumed to be implemented with contact laser scalpel. The mathematical model consists of two inhomogeneous nonlinear equations of heatconductivity with spherical symmetry. Nonstationary temperature fields of tissue and blood are determined and the main parameters are: (1) coefficients of heatconductivity and capacitance of blood and tissue, (2) blood and tissue density, (3) total metabolic energy, (4) volume coefficient accounting for heat-exchange between tissue and blood, and (5) blood circulation velocity. The power of laser radiation was taken into account in boundary conditions set for the center of coagulated tissue volume. We also took into account the process connected with changing of substance phase (vaporization). The original computer programs allow one to solve the problem varying in a wide range of the main parameters. Reasonable agreement was found between the calculation results and the experimental data for operations on microsamples and on test animals. It was demonstrated, in particular, that liver tissue coagulation regime is achieved at 10 W laser power during 25 s. The coagulation radius of 0.7 cm with the given tumor radius of 0.5 cm corresponds to the real clinical situation in case of metastasis liver affection.

Canine transurethral laser prostatectomy using a rotational technique

NASA Astrophysics Data System (ADS)

Cromeens, Douglas M.; Johnson, Douglas E.

1995-05-01

Conventional radical prostatectomy in the dog has historically been attended by unacceptably high incidence of urinary incontinence (80 - 100%). Ablation of the prostate can be accomplished in the dog by transurethral irradiation of the prostate with the Nd:YAG laser and a laterally deflecting fiber. Exposure has ranged between 40 and 60 watts for 60 seconds at 4 fixed locations. Although prostatectomies performed with the above described technique offers significant advantage over conventional prostatectomies, the high power density at each location can result in small submucosal explosions (`popcorn effect') that increase the potential for bleeding and rupture of the prostatic capsule. We describe a new technique in which the energy is applied continuously by a laser fiber rotating around a central point. Delivering 40 watts of Nd:YAG energy for 4 minutes using a new angle-delivery device (UrotekTM), we produced results comparable to those of other previously reported techniques in the canine model with two added advantages: (1) a more even application of heat resulting in no `popcorn' effect and (2) a more reliably predictable area of coagulative necrosis within a given axial plane. This technique should provide additional safety for the veterinary surgeon performing visual laser ablation of the prostate in the dog.

New application system for simultaneous laser and ultrasonic transmission in endoscopic surgery (LUST)

NASA Astrophysics Data System (ADS)

Desinger, Kai; Helfmann, Juergen; Stein, Thomas; Liebold, K.; Mueller, Gerhard J.

1998-04-01

A new combined Laser and Ultrasound Surgical Therapy (LUST) device for an endoscopically suitable coagulation and tissue fragmentation based on the transmission of laser radiation and ultrasound via flexible silica glass fibers was developed at the LMTB. The ultrasound tissue interaction is based on the well-known CUSA-technology, which enables the surgeon to cut various types of tissue with different degrees of effectiveness. This selective cutting performance is a very useful feature, e.g. for a brain tumor extirpation, where it must be guaranteed that vessels and nerves are not affected while ensuring a fast reduction of the tumor mass. Application fields are in oncology, neurosurgery and angioplasty. The laser radiation can be used for tissue coagulation purposes and homeostasis. With a fiber based LUST-system working at a resonance frequency of 30 kHz, using a laser-vibrometer, velocity amplitudes of up to 20 m/s could be detected at the distal end which corresponds to an elongation of more than 100 micrometers . The investigations have shown that the velocity amplitude, next to suction, frequency and cross section of the active fiber tip, has the greatest impact on the fragmentation rate. With a suction setting of 5 W, the following tissue fragmentation rates could be achieved with a 1.3 mm2 fiber cross section and a tip amplitude velocity of 12 m/s: brain tissue 50 mg/s, liver 4,5 mg/s and kidney 4 mg/s. Laser radiation up to 25 watt was sufficient to coagulate soft tissue. This new approach in developing an application system for the therapeutical use of laser radiation and ultrasound via optical waveguides offers new possibilities in minimally invasive surgery, providing a complete new working sphere for the surgeon. The flexible opto-acoustic waveguide (400 - 1700 micrometers ) can be bent making areas accessible which were inaccessible before. The surgeon can use the laser radiation for tissue coagulation or cutting and the ultrasound for tissue fragmentation and tissue reduction without changing the instrumentation.

Laser Treatment of Benign Prostatic Hyperplasia: Dosimetric and Thermodynamic Considerations

NASA Astrophysics Data System (ADS)

Anvari, Bahman

1993-01-01

Benign prostatic hyperplasia (BPH) is the most commonly occurring neoplastic disease in the aging human male. Currently, surgical treatment of BPH is the primary therapeutic method. However, due to surgical complications, less invasive methods of treatment are desirable. In recent years, thermal coagulation of the hyperplastic prostate by a laser has received a considerable amount of attention. Nevertheless, the optimum laser irradiation parameters that lead to a successful and safe treatment of BPH have not been determined. This dissertation studies the physics of laser coagulation of prostate from both basic science and practical perspectives. Optical properties of prostatic tissue are determined over a spectrum of wavelengths. Knowledge of these properties allows for selection of appropriate laser wavelengths and provides a basis for performing dose equivalency studies among various types of lasers. Furthermore, knowledge of optical properties are needed for development of computer simulation models that predict the extent of thermal injury during laser irradiation of prostate. A computer model of transurethral heating of prostate that can be used to guide the clinical studies in determining an optimum dosimetry is then presented. Studies of the effects of non-laser heating devices, optical properties, blood perfusion, surface irrigation, and beam geometry are performed to examine the extent of heat propagation within the prostate. An in vitro model for transurethral laser irradiation of prostate is also presented to examine the effects of an 810 nm diode laser, thermal boundary conditions, and energy deposition rate during Nd:YAG laser irradiation. Results of these studies suggest that in the presence of laminar irrigation, the convective boundary condition is dominated by thermal diffusion as opposed to the bulk motion of the irrigation fluid. Distinct phases of thermal events are also identified during the laser irradiation. The in vivo studies of transurethral laser irradiation of prostate in canine models are also performed to search for an optimum dosimetry that will result in a maximum zone of coagulation necrosis.

Photocoagulation as treatment of diabetic retinopathy

NASA Astrophysics Data System (ADS)

Sanchez, J.; Fernandez, L.; de Pedraza, Maria L.; Gamella, C.; Santervas, R.

1992-03-01

Diabetes Mellitus is a chronic disease that is revealed with a lot of alterations due to factors such as an absolute or relative reduction of the insulin. It is usually accompanied by generalized arteriosclerosis and prepares for certain microvasculares pathologies such as retinopathy, nefropathy, and neuropathy. The first effects of diabetes in the retina seem to act on the capillaries. The functional modifications of the retinal circulation appear before the structural ones. These consist of the blood flux damage and the obligation of the hematorretinal barrier with extravasacy as can be proved in the fluorophotometry of the vitreous humor. Nowadays, medical treatments are more effective and only vitrectomy and photocoagulation are used in diabetic retinopathy. For that, the argon laser and the xenon arch are used. The treatment is usually spread panretine, with coagulation in a grid pattern around the eye, avoiding the macula and other vital structures, and treating the neoformed blood vessels. The rate of grave visual loss in the studies carried out with there techniques was 12 in relation to 28 in the non-treated cases. The most important factors of risk found, were the discal neoformed blood vessels and the hemorrhage of the vitreous humor. Adverse effects were found such as the reduction of visual sharpness and the contrition of the visual field, these are greater in patients treated with the xenon arch than in those treated with the argon laser.

From coagulation to enucleation: the use of lasers in surgery for benign prostatic hyperplasia.

PubMed

Wilson, Liam C; Gilling, Peter J

2005-09-01

The application of lasers for the treatment of benign prostatic hyperplasia has evolved over the past 15 years. Early-generation neodymium:yttrium aluminum garnet lasers were used to coagulate and ablate prostatic tissue, but significant postoperative irritative symptoms and high reoperation rates meant that this approach did not seriously challenge the status quo for long. Ablative techniques have recently become popular again with the marketing of the newer-generation, higher-power potassium titanyl phosphate and holmium lasers. Although short-term data are encouraging, there are no comparative trials of significant duration, so it is not yet possible to draw conclusions with regard to efficacy and durability. The holmium laser can also be used as an incisional and dissecting tool that allows resection or enucleation of whole lobes of the prostate, mimicking the action of the index finger in open prostatectomy. The safety, efficacy, durability and cost-effectiveness of the holmium laser have been shown in well-designed randomized controlled trials.

Holmium laser use in the treatment of selected dry eye syndrome complications

NASA Astrophysics Data System (ADS)

Kecik, Dariusz; Kecik, Tadeusz; Kasprzak, Jan; Kecik, Mariusz

1996-03-01

The authors present initial results of treatment selected complications of dry eye syndrome with holmium laser. The lacrimal puncta obliteration and coagulation of the corneal ulcer surface were done.

Current status of lasers in soft tissue dental surgery.

PubMed

Pick, R M; Colvard, M D

1993-07-01

The aims of this paper are to briefly describe laser physics, the types of lasers currently available for use on soft tissues focusing primarily on CO2 and Nd:YAG laser energies, the histological effects of lasers on oral tissues, laser safety, the clinical applications of lasers on oral soft tissues, and future directions. Of the two types of lasers currently available for dental applications, both the CO2 and Nd:YAG lasers can be used for frenectomies, ablation of lesions, incisional and excisional biopsies, gingivectomies, gingivoplasties, soft tissue tuberosity reductions, operculum removal, coagulation of graft donor sites, and certain crown lengthening procedures. The advantages of lasers include a relatively bloodless surgical and post-surgical course, minimal swelling and scarring, coagulation, vaporization, and cutting, minimal or no suturing, reduction in surgical time, and, in a majority of cases, much less or no post-surgical pain. CO2 lasers, compared to Nd:YAG are faster for most procedures, with less depth of tissue penetration and a well-documented history. There have been recent reports on the use of the Nd:YAG laser for periodontal scaling, gingival curettage, and root desensitization, but further research needs to be conducted. Both the CO2 and the Nd:YAG laser have limited use in conventional flap therapy.

An optical approach for non-invasive blood clot testing

NASA Astrophysics Data System (ADS)

Kalchenko, Vyacheslav; Brill, Alexander; Fine, Ilya; Harmelin, Alon

2007-02-01

Physiological blood coagulation is an essential biological process. Current tests for plasma coagulation (clotting) need to be performed ex vivo and require fresh blood sampling for every test. A recently published work describes a new, noninvasive, in vivo approach to assess blood coagulation status during mechanical occlusion1. For this purpose, we have tested this approach and applied a controlled laser beam to blood micro-vessels of the mouse ear during mechanical occlusion. Standard setup for intravital transillumination videomicroscopy and laser based imaging techniques were used for monitoring the blood clotting process. Temporal mechanical occlusion of blood vessels in the observed area was applied to ensure blood flow cessation. Subsequently, laser irradiation was used to induce vascular micro-injury. Changes in the vessel wall, as well as in the pattern of blood flow, predispose the area to vascular thrombosis, according to the paradigm of Virchow's triad. In our experiments, two elements of Virchow's triad were used to induce the process of clotting in vivo, and to assess it optically. We identified several parameters that can serve as markers of the blood clotting process in vivo. These include changes in light absorption in the area of illumination, as well as changes in the pattern of the red blood cells' micro-movement in the vessels where blood flow is completely arrested. Thus, our results indicate that blood coagulation status can be characterized by non-invasive, in vivo methodologies.

Interstitial laser coagulation of benign prostatic hyperplasia: a minimally invasive treatment alternative

NASA Astrophysics Data System (ADS)

Ordonez, Robert F.; Mittemeyer, Bernhard T.; Aronoff, David R.; de Riese, Werner T. W.

2003-06-01

The use of minimally invasive treatments for benign prostatic hyperplasia (BPH) have been introduced into the medical community. Over the last decade several minimally invasive treatment techniques have been approved for use. In particular, interstitial laser coagulation (ILC) has shown pomise as an alternative to the current gold standard, transurethral resection of prostate (TURP). Studies show ILC to have equal efficacy as TURP while causing less side effects. Future technical advances as well as increased physician experience with ILC could lead to the replacement of TURP as the gold standard in trestment of BPH.

Technique development for photoacoustic imaging guided interventions

NASA Astrophysics Data System (ADS)

Cheng, Qian; Zhang, Haonan; Yuan, Jie; Feng, Ting; Xu, Guan; Wang, Xueding

2015-03-01

Laser-induced thermotherapy (LITT), i.e. tissue destruction induced by a local increase of temperature by means of laser light energy transmission, has been frequently used for minimally invasive treatments of various diseases such as benign thyroid nodules and liver cancer. The emerging photoacoustic (PA) imaging, when integrated with ultrasound (US), could contribute to LITT procedure. PA can enable a good visualization of percutaneous apparatus deep inside tissue and, therefore, can offer accurate guidance of the optical fibers to the target tissue. Our initial experiment demonstrated that, by picking the strong photoacoustic signals generated at the tips of optical fibers as a needle, the trajectory and position of the fibers could be visualized clearly using a commercial available US unit. When working the conventional US Bscan mode, the fibers disappeared when the angle between the fibers and the probe surface was larger than 60 degree; while working on the new PA mode, the fibers could be visualized without any problem even when the angle between the fibers and the probe surface was larger than 75 degree. Moreover, with PA imaging function integrated, the optical fibers positioned into the target tissue, besides delivering optical energy for thermotherapy, can also be used to generate PA signals for on-line evaluation of LITT. Powered by our recently developed PA physio-chemical analysis, PA measurements from the tissue can provide a direct and accurate feedback of the tissue responses to laser ablation, including the changes in not only chemical compositions but also histological microstructures. The initial experiment on the rat liver model has demonstrated the excellent sensitivity of PA imaging to the changes in tissue temperature rise and tissue status (from native to coagulated) when the tissue is treated in vivo with LITT.

Three-frequency Nd:YAG laser for dental treatment

NASA Astrophysics Data System (ADS)

Kadlecová, Martina; Dostálová, Tat'jana; Jelínková, Helena; Němec, Michal; Å ulc, Jan; Fibrich, Martin; Bradna, Pavel; Nejezchleb, Karel; Kapitch, Nickalai; Å koda, Václav

2018-02-01

In the last decade, lasers found a number of indications in dentistry. However, there is still one problem: the narrow spectrum of usefulness for individual radiation wavelengths. The aim of our study is to demonstrate the use of a compact three-frequency pulsed Nd-YAG laser for more than one treatment, namely disinfection, coagulation, selective ablation, and soft tissue removal. The laser wavelengths and the maximal energies achieved were the following: 1.06 um, 1.32 um, 1.44 um and 830 mJ, 425 mJ, and 200 mJ, respectively. It has been found that all of the investigated wavelengths exhibit disinfection properties. Moreover, radiation of 1.06 um wavelength removes soft tissue and exhibits also coagulation properties. Radiation of 1.44 um is most useful for selective ablation of initial caries and disinfection, and 1.32 um radiation can be used for precise ablation when higher energy is applied.

Noninvasive laser coagulation of the canine vas deferens, ex vivo

NASA Astrophysics Data System (ADS)

Cilip, Christopher M.; Jarow, Jonathan P.; Fried, Nathaniel M.

2009-02-01

Male sterilization (vasectomy) is more successful, safer, less expensive, and easier to perform than female sterilization (tubal ligation). However, female sterilization is more popular, due to male fear of vasectomy complications (e.g. incision, bleeding, infection, and scrotal pain). The development of a completely noninvasive vasectomy technique may allay some of these concerns. Ytterbium fiber laser radiation with a wavelength of 1075 nm, average power of 11.7 W, 1-s pulse duration, 0.5 Hz pulse rate, and 3-mm-diameter spot was synchronized with cryogen cooling of the scrotal skin surface in canine tissue for a treatment time of 60 s. Vas thermal lesion dimensions measured 2.0 +/- 0.3 mm diameter by 3.0 +/- 0.9 mm length, without skin damage. The coagulated vas bursting pressure measured 295 +/- 72 mm Hg, significantly higher than typical vas ejaculation pressures of 136 + 29 mm Hg. Noninvasive thermal coagulation and occlusion of the vas is feasible.

Laser radiation in tennis elbow treatment: a new minimally invasive alternative

NASA Astrophysics Data System (ADS)

Paganini, Stefan; Thal, Dietmar R.; Werkmann, Klaus

1998-01-01

The epicondylitis humeri radialis (EHR) (tennis elbow), is a common disease in elbow joint pain syndromes. We treated patients with chronic pain for at least one year and no improvement with conservative or operative therapies with a new minimal invasive method, the EHR-Laser radiation (EHR- LR). With this method periepicondylar coagulations were applied to the trigger points of the patients. For this the previously established technique of facet joint coagulation with the Nd:Yag-laser was modified. In a follow-up study of between 6 weeks and 2 years all patients reported either a significant pain reduction or were symptom free. EHR-LR is a new method situated between conservative and surgical treatments for minimal invasive therapy of EHR. Several therapeutic rationales were discussed for the resulting pain reduction.

The holmium laser in urology.

PubMed

Wollin, T A; Denstedt, J D

1998-02-01

To review the physics related to the holmium laser, its laser-tissue interactions, and its application to the treatment of urological diseases. The holmium: YAG laser is a solid-state, pulsed laser that emits light at 2100 nm. It combines the qualities of the carbon dioxide and neodymium:YAG lasers providing both tissue cutting and coagulation in a single device. Since the holmium wavelength can be transmitted down optical fibers, it is especially suited for endoscopic surgery. The authors provide a review of the literature as it relates to the holmium laser and its application to urology. The holmium wavelength is strongly absorbed by water. Tissue ablation occurs superficially, providing for precise incision with a thermal injury zone ranging from 0.5 to 1.0 mm. This level of coagulation is sufficient for adequate hemostasis. The most common urologic applications of the holmium laser that have been reported include incision of urethral and ureteral strictures; ablation of superficial transitional cell carcinoma; bladder neck incision and prostate resection; and lithotripsy of urinary calculi. The holmium: YAG laser is a multi-purpose, multi-specialty surgical laser. It has been shown to be safe and effective for multiple soft tissue applications and stone fragmentation. Its utilization in urology is anticipated to increase with time as a result of these features.

Laboratory and clinical experience with neodymium:YAG laser prostatectomy

NASA Astrophysics Data System (ADS)

Kabalin, John N.

1996-05-01

Since 1991, we have undertaken extensive laboratory and clinical studies of the Neodymium:YAG (Nd:YAG) laser for surgical treatment of bladder outlet obstruction due to prostatic enlargement or benign prostatic hyperplasia (BPH). Side-firing optical fibers which emit a divergent, relatively low energy density Nd:YAG laser beam produce coagulation necrosis of obstructing periurethral prostate tissue, followed by gradual dissolution and slough in the urinary stream. Laser-tissue interactions and Nd:YAG laser dosimetry for prostatectomy have been studied in canine and human prostate model systems, enhancing clinical application. Ongoing studies examine comparative Nd:YAG laser dosimetry for various beam configurations produced by available side-firing optical fibers and continue to refine operative technique. We have documented clinical outcomes of Nd:YAG laser prostatectomy in 230 consecutive patients treated with the UrolaseTM side-firing optical fiber. Nd:YAG laser coagulation the prostate produces a remarkably low acute morbidity profile, with no significant bleeding or fluid absorption. No postoperative incontinence has been produced. Serial assessments of voiding outcomes over more than 3 years of followup show objective and symptomatic improvement following Nd:YAG laser prostatectomy which is comparable to older but more morbid electrosurgical approaches. Nd:YAG laser prostatectomy is a safe, efficacious, durable and cost-effective treatment for BPH.

Le Laser A Argon Ionise : Applications Therapeutiques

NASA Astrophysics Data System (ADS)

Brunetaud, J. M.; Mosquet, L.; Mordon, S.; Rotteleur, G.

1984-03-01

Le laser a argon ionise est un laser a emission continue, reglee en general en multiraies de 487 a 544 nm. Le rayonnement de ce laser est bien absorbe par les tissus vivants, avec une action preferentielle au niveau des pigments rouges (hemoglobine, myoglobine) et noirs (melanine). Le laser a argon est princi-palement utilise en therapeutique pour ses effets thermiques : en fonction du choix des parametres (puissance optique, surface exposee, temps d'exposition) on peut obtenir une coagulation (temperature optimale au niveau des tissus 60° - 80°) ou une volatisation (temperature superieure a 100°). Si la zone volatilisee est tres etroite (inferieure a 0,5 mm) on obtient un effet de coupe. Par rapport aux deux autres lasers egalement utilises pour leurs effets thermiques (CO2 et Nd. YAG) l'argon a des effets intermediaires : la coagulation sera plus superficielle qu'avec le Nd. YAG et la volatisation plus profonde qu'avec le CO2. Lors de la coupe, la necrose sur les berges sera egalement plus importante qu'avec le CO2.

Effects of the holmium laser on the human cornea: a preliminary study

NASA Astrophysics Data System (ADS)

Mueller, Linda J.; Tassignon, Marie J.; Trau, Rene; Pels, Liesbeth; Vrensen, Gijs F.

1996-12-01

Treatment of peripheral post-mortem human corneas with the Holmium laser in a ring pattern resulted in opaque spots. One pair of treated eyes was immediately processed for light and electron microscopy and three other treated eyes were preserved for 4 days in medium in order to compare direct and short-term effects of the Holmium laser. Cross as well as frontal light microscopical sections of all eyes revealed interconnecting bands between the spots. At the ultrastructural level the anterior corneal tissue within these spots was characterized by coagulation of cells and collagen and shoed either a dramatic distorting effect on the epithelium in the eyes processed immediately or a single layer of flattened multi-nucleolated epithelial cells having more than one nucleolus per nucleus in the eyes stored in medium. Furthermore, the spots showed disturbed Bowman's layer, destroyed keratocytes and collagen fibrils which were either coagulated or organized chaotically. The interconnecting bands contained alternating normal and coagulated collagen fibers. The rest of the cornea outside the spots had a normal appearance. In corneas stored in medium, both keratocytes and epithelial cells over the entire cornea exhibited accumulations of cytoplasmic fibrils and glycogen particles. These phenomena were not observed in non-preserved corneas, suggesting that the differences are due to preservation and not due to the laser treatment. It is concluded that morphological changes occur mainly in the treated peripheral cornea whereas the central untreated cornea remains unaffected,indicating that the Holmium laser is a reliable instrument to treat hypermetropic patients.

Hemostatic properties of the free-electron laser

NASA Astrophysics Data System (ADS)

Cram, Gary P., Jr.; Copeland, Michael L.

1998-09-01

We have investigated the hemostatic properties of the free-electron laser (FEL) and compared these properties to the most commonly used commercial lasers in neurosurgery, CO 2 and Nd:YAG, using an acute canine model. Arterial and venous vessels, of varying diameters from 0.1 to 1.0 mm, were divided with all three lasers. Analysis of five wavelengths of the FEL (3.0, 4.5, 6.1, 6.45, and 7.7 microns) resulted in bleeding without evidence of significant coagulation, regardless of whether the vessel was an artery or vein. Hemorrhage from vessels less than 0.4 mm diameter was subsequently easily controlled with Gelfoam® (topical hemostatic agent) alone, whereas larger vessels required bipolar electrocautery. No significant charring, or contraction of the surrounding parenchyma was noted with any of the wavelengths chosen from FEL source. The CO 2 laser, in continuous mode, easily coagulated vessels with diameters of 4 mm and less, while larger vessels displayed significant bleeding requiring bipolar electrocautery for control. Tissue charring was noted with application of the CO 2 laser. In super pulse mode, the CO 2 laser exhibited similar properties, including significant charring of the surrounding parenchyma. The Nd:YAG coagulated all vessels tested up to 1.4 mm, which was the largest diameter cortical artery found, however this laser displayed significant and extensive contraction and retraction of the surrounding parenchyma. In conclusion, the FEL appears to be a poor hemostatic agent. Our results did not show any benefit of the FEL over current conventional means of achieving hemostasis. However, control of hemorrhage was easily achieved with currently used methods of hemostasis, namely Gelfoam® or bipolar electrocuatery. Although only cortical vessels in dogs were tested, we feel this data can be applied to all animals, including humans, and the peripheral, as well as central, vasculature, as our data on the CO 2 and Nd:YAG appear to closely support previous reports of hemostasis of these two lasers obtained in other models.

Towards real time speckle controlled retinal photocoagulation

NASA Astrophysics Data System (ADS)

Bliedtner, Katharina; Seifert, Eric; Stockmann, Leoni; Effe, Lisa; Brinkmann, Ralf

2016-03-01

Photocoagulation is a laser treatment widely used for the therapy of several retinal diseases. Intra- and inter-individual variations of the ocular transmission, light scattering and the retinal absorption makes it impossible to achieve a uniform effective exposure and hence a uniform damage throughout the therapy. A real-time monitoring and control of the induced damage is highly requested. Here, an approach to realize a real time optical feedback using dynamic speckle analysis is presented. A 532 nm continuous wave Nd:YAG laser is used for coagulation. During coagulation, speckle dynamics are monitored by a coherent object illumination using a 633nm HeNe laser and analyzed by a CMOS camera with a frame rate up to 1 kHz. It is obvious that a control system needs to determine whether the desired damage is achieved to shut down the system in a fraction of the exposure time. Here we use a fast and simple adaption of the generalized difference algorithm to analyze the speckle movements. This algorithm runs on a FPGA and is able to calculate a feedback value which is correlated to the thermal and coagulation induced tissue motion and thus the achieved damage. For different spot sizes (50-200 μm) and different exposure times (50-500 ms) the algorithm shows the ability to discriminate between different categories of retinal pigment epithelial damage ex-vivo in enucleated porcine eyes. Furthermore in-vivo experiments in rabbits show the ability of the system to determine tissue changes in living tissue during coagulation.

External and intralesional photocoagulation of hemangioma in children with infrared diode laser

NASA Astrophysics Data System (ADS)

Abushkin, Ivan A.; Privalov, Valery A.; Lappa, Alexander V.; Besshtanko, Evgeny L.

2005-08-01

Infra-red diode laser with wavelength 1060 nm was used for combined treatment of 163 children aged from 21 days to 13 years with 221 hemangiomas. For interstitial coagulation a power of 1.8-2 W and a power density of 5-90 J/cm3 were used in continuous mode. For distant coagulation pulse mode was applied with pulse/pause duration 30-50/200-250 ms, average power 1.3-2 W, and power density 65-450 J/cm2. 197 (89.1 %) hemangiomas were capillary, 7 (3.2 %) cavernous, and 17 (7.7 %) combined (combination of capillary and cavernous hemangiomas). The area of hemangiomas ranged from 6 mm2 to 48 cm2. For the majority (193, 87.3 %) of hemangiomas one session of photocoagulation was enough to achieve a good cosmetic effect. However, 28 (12.7 %) hemangiomas were treated repeatedly, 11 (5%) of them needed 4-7 sessions. In 8 children with cavernous and combined hemangiomas both distant and interstitial laser coagulation were used. In all, good or excellent results were obtained in 96,3 % of the patients. In 6 (3.7%) patients with extensive combined hematomas the considerable improvement was achieved.

Er:YAG and Nd:YAG laser in treatment of patients with contraindications of conventional dental and maxillofacial surgery

NASA Astrophysics Data System (ADS)

Smucler, Roman; Mazanek, Jiri

2000-03-01

In clinical praxis we must treat patients with some relative or absolute contraindications every day. Need of hospitalization, antibiotics, hemostyptics and complex examinations makes dentoalveolar and maxillofacial surgery in those cases quite expensive. Combination of Nd:YAG and Er:YAG laser gives us new possibilities. We can help some untreatable patients or transfer care from hospital to dental office. We have been trying to solve contraindications for laser therapy five years. In the center of our work are disorders of blood coagulation, immunity and metabolism. Nd:YAG laser is very useful in coagulation and vaporization of dental gum hypertrophies, benign and malign tumors in case of chronic anticoagulation therapy and immunosupress / in combination for example- after heart transplantation /. Special chapter is the care of patients with disseminated tumors. Er:YAG laser large solve big lesions because of minimal invasivity of course but for small benign tumors are recidives is ideal. Better and quicker healing make new standard of patients' cooperation. Generally fashionable and more comfortable laser treatment minimize need of general anesthesia. After five years we use complex laser therapy in our routine. Aim of our new work is to find ideal combination of cutting lasers to minimize classical complications of laser surgery / carbonization, long and secondary healing /.

Photothermal effect of infrared lasers on ex vivo lamb brain tissues

NASA Astrophysics Data System (ADS)

Özgürün, Baturay; Gülsoy, Murat

2018-02-01

Here, the most suitable infrared laser for a neurosurgery operation is suggested, among 1940-nm thulium fiber, 1470-nm diode, 1070-nm ytterbium fiber and 980-nm diode lasers. Cortical and subcortical ex-vivo lamb brain tissues are exposed to the laser light with the combinations of some laser parameters such as output power, energy density, operation mode (continuous and pulsed-modulated) and operation time. In this way, the greatest ablation efficiency associated with the best neurosurgical laser type can be defined. The research can be divided into two parts; pre-dosimetry and dosimetry studies. The former is used to determine safe operation zones for the dosimetry study by defining coagulation and carbonization onset times for each of the brain tissues. The latter is the main part of this research, and both tissues are exposed to laser irradiation with various energy density levels associated with the output power and operation time. In addition, photo-thermal effects are compared for two laser operation modes, and then coagulation and ablation diameters to calculate the ablation efficiency are measured under a light microscope. Consequently, results are compared graphically and statistically, and it is found that thulium and 1470-nm diode lasers can be utilized as subcortical and cortical tissue ablator devices, respectively.

Influence of fat replacement by inulin on rheological properties, kinetics of rennet milk coagulation, and syneresis of milk gels.

PubMed

Arango, O; Trujillo, A J; Castillo, M

2013-04-01

The objective of this study was to evaluate the effect of inulin as a fat replacer on the rheological properties, coagulation kinetics, and syneresis of milk gels. A randomized factorial design, replicated 3 times, with 3 inulin concentrations (0, 3, and 6%), 2 levels of fat (<0.2 and 1.5%), and 3 coagulation temperatures (27, 32, and 37°C) was used. The coagulation process was monitored using near-infrared spectrometry, small amplitude oscillatory rheometry, and visual coagulation indexes. The syneresis was evaluated by volumetric methods. Inulin addition increased the rates of aggregation and curd firming reactions in the casein gels. The observed effect, which was more evident on the aggregation reaction, depended on the concentration of inulin and the coagulation temperature. Addition of 6% inulin reduced the clotting time by approximately 26% and the time at which the gel reached a storage modulus equal to 30 Pa by approximately 36%. The optical parameter R'max, defined as the maximum value of change in light backscatter profile/change in time (where R' = dR/dt), was used to calculate an approximation of the temperature coefficients (Q10) for milk coagulation. Increasing fat concentration induced a consistent increase in all the optical, rheological, and visual parameters studied, although the observed trend was not statistically significant. The addition of inulin at a level of 6% produced a reduction in syneresis and increased the curd yield by approximately 30%. It was concluded that the addition of inulin affects the kinetics of milk coagulation and the cutting time and, therefore, the use of inline sensors such as near-infrared spectrometry may be necessary for optimal process control. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Arabin cervical pessary for prevention of preterm birth in cases of twin-to-twin transfusion syndrome treated by fetoscopic LASER coagulation: the PECEP LASER randomised controlled trial.

PubMed

Rodó, Carlota; Arévalo, Sílvia; Lewi, Liesbeth; Couck, Isabel; Hollwitz, Bettina; Hecher, Kurt; Carreras, Elena

2017-08-01

Fetoscopic LASER coagulation of the placental anastomoses has changed the prognosis of twin-twin transfusion syndrome. However, the prematurity rate in this cohort remains very high. To date, strategies proposed to decrease the prematurity rate have shown inconclusive, if not unfavourable results. This is a randomised controlled trial to investigate whether a prophylactic cervical pessary will lower the incidence of preterm delivery in cases of twin-twin transfusion syndrome requiring fetoscopic LASER coagulation. Women eligible for the study will be randomised after surgery and allocated to either pessary or expectant management. The pessary will be left in place until 37 completed weeks or earlier if delivery occurs. The primary outcome is delivery before 32 completed weeks. Secondary outcomes are a composite of adverse neonatal outcome, fetal and neonatal death, maternal complications, preterm rupture of membranes and hospitalisation for threatened preterm labour. 352 women will be included in order to decrease the rate of preterm delivery before 32 weeks' gestation from 40% to 26% with an alpha-error of 0.05 and 80% power. The trial aims at clarifying whether the cervical pessary prolongs the pregnancy in cases of twin-twin transfusion syndrome regardless of cervical length at the time of fetoscopy. ClinicalTrials.gov Identifier: NCT01334489 . Registered 04 December 2011.

Infrared laser thermal fusion of blood vessels: preliminary ex vivo tissue studies.

PubMed

Cilip, Christopher M; Rosenbury, Sarah B; Giglio, Nicholas; Hutchens, Thomas C; Schweinsberger, Gino R; Kerr, Duane; Latimer, Cassandra; Nau, William H; Fried, Nathaniel M

2013-05-01

Suture ligation of blood vessels during surgery can be time-consuming and skill-intensive. Energy-based, electrosurgical, and ultrasonic devices have recently replaced the use of sutures and mechanical clips (which leave foreign objects in the body) for many surgical procedures, providing rapid hemostasis during surgery. However, these devices have the potential to create an undesirably large collateral zone of thermal damage and tissue necrosis. We explore an alternative energy-based technology, infrared lasers, for rapid and precise thermal coagulation and fusion of the blood vessel walls. Seven near-infrared lasers (808, 980, 1075, 1470, 1550, 1850 to 1880, and 1908 nm) were tested during preliminary tissue studies. Studies were performed using fresh porcine renal vessels, ex vivo, with native diameters of 1 to 6 mm, and vessel walls flattened to a total thickness of 0.4 mm. A linear beam profile was applied normal to the vessel for narrow, full-width thermal coagulation. The laser irradiation time was 5 s. Vessel burst pressure measurements were used to determine seal strength. The 1470 nm laser wavelength demonstrated the capability of sealing a wide range of blood vessels from 1 to 6 mm diameter with burst strengths of 578 ± 154, 530 ± 171, and 426 ± 174  mmHg for small, medium, and large vessel diameters, respectively. Lateral thermal coagulation zones (including the seal) measured 1.0 ± 0.4  mm on vessels sealed at this wavelength. Other laser wavelengths (1550, 1850 to 1880, and 1908 nm) were also capable of sealing vessels, but were limited by lower vessel seal pressures, excessive charring, and/or limited power output preventing treatment of large vessels (>4  mm outer diameter).

Laser speckle contrast imaging of skin blood perfusion responses induced by laser coagulation

NASA Astrophysics Data System (ADS)

Ogami, M.; Kulkarni, R.; Wang, H.; Reif, R.; Wang, R. K.

2014-08-01

We report application of laser speckle contrast imaging (LSCI), i.e., a fast imaging technique utilising backscattered light to distinguish such moving objects as red blood cells from such stationary objects as surrounding tissue, to localise skin injury. This imaging technique provides detailed information about the acute perfusion response after a blood vessel is occluded. In this study, a mouse ear model is used and pulsed laser coagulation serves as the method of occlusion. We have found that the downstream blood vessels lacked blood flow due to occlusion at the target site immediately after injury. Relative flow changes in nearby collaterals and anastomotic vessels have been approximated based on differences in intensity in the nearby collaterals and anastomoses. We have also estimated the density of the affected downstream vessels. Laser speckle contrast imaging is shown to be used for highresolution and fast-speed imaging for the skin microvasculature. It also allows direct visualisation of the blood perfusion response to injury, which may provide novel insights to the field of cutaneous wound healing.

Blood coagulation profiling in patients using optical thromboelastography (OTEG) (Conference Presentation)

NASA Astrophysics Data System (ADS)

Tripathi, Markandey M.; Tshikudi, Diane M.; Hajjarian, Zeinab; Van Cott, Elizabeth M.; Nadkarni, Seemantini K.

2016-02-01

Impaired blood coagulation is often associated with increased postoperative mortality and morbidity in cardiovascular patients. The capability for blood coagulation profiling rapidly at the bedside will enable the timely detection of coagulation defects and open the opportunity for tailoring therapy to correct specific coagulation deficits Optical Thromboelastography (OTEG), is an optical approach to quantify blood coagulation status within minutes using a few drops of whole blood. The goal of the current study is to evaluate the diagnostic accuracy of OTEG for rapid coagulation profiling in patients. In OTEG, temporal laser speckle intensity fluctuations from a drop of clotting blood are measured using a CMOS camera. To quantify coagulation status, the speckle intensity autocorrelation function is measured, the mean square displacement of scattering particles is extracted, and viscoelastic modulus (G), during coagulation is measured via the generalized Stokes-Einstein relation. By quantifying time-resolved changes in G, the coagulation parameters, reaction time (R), clot progression time (K), clot progression rate (Angle), and maximum clot strength (MA) are derived. In this study, the above coagulation parameters were measured using OTEG in 269 patients and compared with standard mechanical Thromboelastography (TEG). Our results showed a strong correlation between OTEG and TEG measurements for all parameters: R-time (R=0.80, p<0.001), clotting time (R=0.78, p<0.001), Angle (R=0.58, p<0.001), and MA (R=0.60, p<0.001). These results demonstrate the unique capability of OTEG for rapid quantification of blood coagulation status to potentially improve clinical capability for identifying impaired coagulation in cardiovascular patients at the point of care.

Dosimetry for photo-coagulation by the use of autofluorescence

NASA Astrophysics Data System (ADS)

Brodzinski, T.

1989-01-01

A basic problem when using lasers in medicine is that of dosimetry. The definition of the terms dose, effective value etc. will be dealt with in Chapter 2. This chapter is intended to give an insight into the problems of basic dosimetry and its technical realization within the field of photocoagulation, an established method used to treat the retina, or some skin diseases. Until now the coagulation process was assessed to be completed when the irradiated area became blanched. However in terms of dosimetry, it must be possible to predict or at least to monitor the biological effect using well-defined parameters for the laser or in achieving an objective measure for a feedback loop. In the case of coagulation, a prediction in this form is not possible. There are two ways of pro- ceeding further see Fig. 1. One can either determine the physical effect, i.e. temperature, by some kind of sensors, or even better, use some biological effect as a direct measure of the effective dose applied.

21 CFR 884.4150 - Bipolar endoscopic coagulator-cutter and accessories.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Bipolar endoscopic coagulator-cutter and accessories. 884.4150 Section 884.4150 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... watts, and (D) For devices with ammeters: continue electrode activation for 5 seconds after the visual...

Red krypton and blue-green argon panretinal laser photocoagulation for proliferative diabetic retinopathy: a laboratory and clinical comparison.

PubMed

Blankenship, G W

1986-01-01

The effects of PRP with red krypton laser are essentially identical to those produced with blue-green argon laser. Burns of the rabbit retina produced with these two different lasers are almost the same. In a prospective and randomized clinical trial of proliferative diabetic retinopathy treatment there was no significant difference between PRP using these two different lasers. The characteristic changes of rabbit fundi 3, 7, and 30 days after PRP with red krypton laser were almost the same as those following blue-green argon laser. Both types of treatment frequently produced small vitreous hemorrhages and exudative retinal detachments, but choroidal thickening occurred more frequently with argon treatment. These changes were transient and had resolved within 30 days of treatment. The microscopic changes consisted of pigment epithelial disruption with pigment migration into the retina, heat coagulation of the photoreceptors, disruption of the outer and inner nuclear layers with atrophy of the nuclei, and temporary swelling of the nerve fiber layer. The untreated retina and choroid between burns was not involved and appeared normal at each period. Thirty days after treatment, the scarring produced by these two types of burns was identical. Seventy-one eyes with proliferative diabetic retinopathy having three or four retinopathy risk factors were treated with panretinal laser photocoagulation, and followed in a prospective study for 6 months. Thirty-six eyes were randomly selected for blue-green argon treatment, and 35 were randomly selected for red krypton treatment. The incidence of undesired side effects during the first 2 weeks following treatment was almost identical between the two groups. However, by 1 month the majority of eyes in both groups had visual acuities equal to or better than the pretreatment acuities and complete regression of NVD. Six months after treatment, the majority of eyes in both groups continued to have visual acuities equal to or better than the pretreatment acuities with fewer cases having larger losses of vision in the krypton treated group. Loss of peripheral visual field was equal with the two types of treatment having a minimal decrease with the IV-4e isopter, but substantial loss with the I-4e isopter. Additional vitreous hemorrhage rarely occurred in either group, but was slightly more frequent in those treated with krypton. Complete regression was accomplished in most eyes with pretreatment disc and/or NVE in both groups, but persistence of neovascularization was more frequent in those treated with krypton. Overall, the wavelength used seemingly had little effect on the result.(ABSTRACT TRUNCATED AT 400 WORDS)

Critical review of lasers in benign prostatic hyperplasia (BPH).

PubMed

Gravas, Stavros; Bachmann, Alexander; Reich, Oliver; Roehrborn, Claus G; Gilling, Peter J; De La Rosette, Jean

2011-04-01

• Laser treatment of benign prostatic hyperplasia has challenged transurethral resection of the prostate (TURP) due to advances in laser technology, better understanding of tissue-laser interactions and growing clinical experience. • Various lasers have been introduced including neodymium: yttrium aluminium garnet (YAG), holmium (Ho):YAG, potassium titanyl phosphate:YAG, thulium(Tm) and diode laser. Based on the different wave-length dependent laser-prostatic tissue interactions, the main techniques are coagulation, vaporization, resection and enucleation. • The present review aims to help urologists to distinguish and to critically evaluate the role of different laser methods in the treatment by using an evidence-based approach. It also details further evidence for use in specific patient groups (in retention, on anticoagulation) and addresses the issues of cost and learning curve. • Coagulation-based techniques have been abandoned; holmium ablation/resection of the prostate has been superseded by the enucleation technique Ho-laser enucleation of the prostate (HoLEP). The short-term efficacy of the emerging laser treatments such as diode and Tm prostatectomy has been suggested by low quality studies. HoLEP and photoselective vaporization of the prostate (PVP) represent valid clinical alternatives to TURP. HoLEP is the most rigorously analysed laser technique with durable efficacy for any prostate size and low early and late morbidity. PVP has grown in acceptance and popularity but long-term results from high quality studies are pending. © 2010 THE AUTHORS; BJU INTERNATIONAL © 2010 BJU INTERNATIONAL.

Realtime temperature determination during retinal photocoagulation on patients

NASA Astrophysics Data System (ADS)

Brinkmann, Ralf; Koinzer, Stefan; Schlott, Kerstin; Ptaszynski, Lars; Bever, Marco; Baade, Alex; Miura, Yoko; Birngruber, Reginald; Roider, Johann

2011-03-01

Retinal photocoagulation is a long time established treatment for a variety of retinal diseases, most commonly applied for diabetic macular edema and diabetic retinopathy. The damage extent of the induced thermal coagulations depend on the temperature increase and the time of irradiation. So far, the induced temperature rise is unknown due to intraocular variations in light transmission and scattering and RPE/choroidal pigmentation, which can vary inter- and intraindividually by more than a factor of four. Thus in clinical practice, often stronger and deeper coagulations are applied than therapeutically needed, which lead to extended retinal damage and strong pain perception. The final goal of this project focuses on a dosimetry control, which automatically generates a desired temperature profile and thus coagulation strength for every individual coagulation spot, ideally unburden the ophthalmologist from any laser settings. In this paper we present the first realtime temperature measurements achieved on patients during retinal photocoagulation by means of an optoacoustic method, making use of the temperature dependence of the thermal expansion coefficient of retinal tissue. Therefore, nanosecond probe laser pulses are repetitively and simultaneously applied with the treatment radiation in order to excite acoustic waves, which are detected at the cornea with an ultrasonic transducer embedded in the contact lens and then are processed by PC.

Effects of cryogen spray cooling and high radiant exposures on selective vascular injury during laser irradiation of human skin.

PubMed

Tunnell, James W; Chang, David W; Johnston, Carol; Torres, Jorge H; Patrick, Charles W; Miller, Michael J; Thomsen, Sharon L; Anvari, Bahman

2003-06-01

Increasing radiant exposure offers a means to increase treatment efficacy during laser-mediated treatment of vascular lesions, such as port-wine stains; however, excessive radiant exposure decreases selective vascular injury due to increased heat generation within the epidermis and collateral damage to perivascular collagen. To determine if cryogen spray cooling could be used to maintain selective vascular injury (ie, prevent epidermal and perivascular collagen damage) when using high radiant exposures (16-30 J/cm2). Observational study. Academic hospital and research laboratory. Twenty women with normal abdominal skin (skin phototypes I-VI). Skin was irradiated with a pulsed dye laser (wavelength = 585 nm; pulse duration = 1.5 milliseconds; 5-mm-diameter spot) using various radiant exposures (8-30 J/cm2) without and with cryogen spray cooling (50- to 300-millisecond cryogen spurts). Hematoxylin-eosin-stained histologic sections from each irradiated site were examined for the degree of epidermal damage, maximum depth of red blood cell coagulation, and percentage of vessels containing perivascular collagen coagulation. Long cryogen spurt durations (>200 milliseconds) protected the epidermis in light-skinned individuals (skin phototypes I-IV) at the highest radiant exposure (30 J/cm2); however, epidermal protection could not be achieved in dark-skinned individuals (skin phototypes V-VI) even at the lowest radiant exposure (8 J/cm2). The red blood cell coagulation depth increased with increasing radiant exposure (to >2.5 mm for skin phototypes I-IV and to approximately 1.2 mm for skin phototypes V-VI). In addition, long cryogen spurt durations (>200 milliseconds) prevented perivascular collagen coagulation in all skin types. Cryogen spurt durations much longer than those currently used in therapy (>200 milliseconds) may be clinically useful for protecting the epidermis and perivascular tissues when using high radiant exposures during cutaneous laser therapies. Additional studies are necessary to prove clinical safety of these protocols.

Prediction of thermal coagulation from the instantaneous strain distribution induced by high-intensity focused ultrasound

NASA Astrophysics Data System (ADS)

Iwasaki, Ryosuke; Takagi, Ryo; Tomiyasu, Kentaro; Yoshizawa, Shin; Umemura, Shin-ichiro

2017-07-01

The targeting of the ultrasound beam and the prediction of thermal lesion formation in advance are the requirements for monitoring high-intensity focused ultrasound (HIFU) treatment with safety and reproducibility. To visualize the HIFU focal zone, we utilized an acoustic radiation force impulse (ARFI) imaging-based method. After inducing displacements inside tissues with pulsed HIFU called the push pulse exposure, the distribution of axial displacements started expanding and moving. To acquire RF data immediately after and during the HIFU push pulse exposure to improve prediction accuracy, we attempted methods using extrapolation estimation and applying HIFU noise elimination. The distributions going back in the time domain from the end of push pulse exposure are in good agreement with tissue coagulation at the center. The results suggest that the proposed focal zone visualization employing pulsed HIFU entailing the high-speed ARFI imaging method is useful for the prediction of thermal coagulation in advance.

Optoacoustic temperature determination and automatic coagulation control in rabbits

NASA Astrophysics Data System (ADS)

Schlott, Kerstin; Koinzer, Stefan; Ptaszynski, Lars; Luft, Susanne; Baade, Alex; Bever, Marco; Roider, Johann; Birngruber, Reginald; Brinkmann, Ralf

2011-03-01

Retinal laser photocoagulation is an established treatment method for many retinal diseases like macula edema or diabetic retinopathy. The selection of the laser parameters is so far based on post treatment evaluation of the lesion size and strength. Due to local pigment variations in the fundus and individual transmission the same laser parameters often lead to an overtreatment. Optoacoustic allows a non invasive monitoring of the retinal temperature increase during retinal laser irradiation by measuring the temperature dependent pressure amplitudes, which are induced by short probe laser pulses. A 75 ns/ 523 nm Nd:YLF was used as a probe laser at a repetition rate of 1 kHz, and a cw / 532 nm treatment laser for heating. A contact lens was modified with a ring-shaped ultrasonic transducer to detect the pressure waves at the cornea. Temperatures were collected for irradiations leading to soft or invisible lesions. Based on this data the threshold for denaturation was found. By analyzing the initial temperature increase, the further temperature development during irradiation could be predicted. An algorithm was found to calculate the irradiation time, which is needed for a soft lesion formation, from the temperature curve. By this it was possible to provide a real-time dosimetry by automatically switching off the treatment laser after the calculated irradiation time. Automatically controlled coagulations appear softer and more uniformly.

Nd:YAG laser combined with gold nanorods for potential application in port-wine stains: an in vivo study

NASA Astrophysics Data System (ADS)

Xing, Linzhuang; Chen, Bin; Li, Dong; Wu, Wenjuan; Wang, Guoxiang

2017-11-01

Neodymium:yttrium aluminum garnet (Nd:YAG) lasers exhibit considerable potential for treating deeply buried port-wine stains. However, the application of Nd:YAG laser is limited by its weak absorption to blood. This in vivo study tested the efficacy and safety of utilizing thiol-terminated methoxypolyethylene glycol-modified gold nanorods (PEG-GNRs) to enhance the absorption of Nd:YAG laser to blood. Mouse mesentery and dorsal skinfold chamber (DSC) model were prepared to analyze the thermal responses of a single venule without anatomic structures, as well as blood vessels in the complex structure of the skin, to laser light. After the injection of 0.44 mg of PEG-GNRs, the required threshold density of laser energy for blood coagulation and complete vasoconstriction decreased from 24 to 18 J/cm2 in the mesentery model and from 36 to 31 J/cm2 in the DSC model. The laser pulse required for blood coagulation and complete vasoconstriction decreased by 67.75% and 62.25% on average in the mesentery model and by 67.55% and 54.45% on average in the DSC model. Histological and histochemical results confirmed that PEG-GNRs are nontoxic in the entire mouse life span. Therefore, combining PEG-GNRs with Nd:YAG laser may be effective and safe for inducing an obvious thermal response of blood vessels under low energy density and minimal pulse conditions.

Examination of contrast mechanisms in optoacoustic imaging of thermal lesions

NASA Astrophysics Data System (ADS)

Richter, Christian; Spirou, Gloria; Oraevsky, Alexander A.; Whelan, William M.; Kolios, Michael C.

2006-02-01

Optoacoustic Imaging is based on the thermal expansion of tissue caused by a temperature rise due to absorption of short laser pulses. At constant laser fluence, optoacoustic image contrast is proportional to differences in optical absorption and the thermoacoustic efficiency, expressed by the Grueuneisen parameter, Γ. Γ is proportional to the thermal expansion coefficient, the sound velocity squared and the inverse heat capacity at constant pressure. In thermal therapies, these parameters may be modified in the treated area. In this work experiments were performed to examine the influence of these parameters on image contrast. A Laser Optoacoustic Imaging System (LOIS, Fairway Medical Technologies, Houston, Texas) was used to image tissue phantoms comprised of cylindrical Polyvinyl Chloride Plastisol (PVCP) optical absorbing targets imbedded in either gelatin or PVCP as the background medium. Varying concentrations of Black Plastic Color (BPC) and titanium dioxide (TiO II) were added to targets and background to yield desired tissue relevant optical absorption and effective scattering coefficients, respectively. In thermal therapy experiments, ex-vivo bovine liver was heated with laser fibres (805nm laser at 5 W for 600s) to create regions of tissue coagulation. Lesions formed in the liver tissue were visible using the LOIS system with reasonable correspondence to the actual region of tissue coagulation. In the phantom experiments, contrast could be seen with low optical absorbing targets (μ a of 0.50cm -1 down to 0.13cm-1) embedded in a gelatin background (see manuscript for formula). Therefore, the data suggest that small objects (< 5mm) with low absorption coefficients (in the range < 1cm -1) can be imaged using LOIS. PVCP-targets in gelatin were visible, even with the same optical properties as the gelatin, but different Γ. The enhanced contrast may also be caused by differences in the mechanical properties between the target and the surrounding medium. PVCP-targets imbedded in PVCP produced poorer image contrast than PVCP-targets in gelatin with comparable optical properties. The preliminary investigation in tissue equivalent phantoms indicates that in addition to tissue optical properties, differences in mechanical properties between heated and unheated tissues may be responsible for image contrast. Furthermore, thermal lesions in liver tissue, ex-vivo, can be visualized using an optoacoustic system.

Histopathology of laser skin resurfacing

NASA Astrophysics Data System (ADS)

Thomsen, Sharon L.; Baldwin, Bonnie; Chi, Eric; Ellard, Jeff; Schwartz, Jon A.

1997-05-01

Pulsed carbon-dioxide laser skin resurfacing is a purportedly 'non-thermal' procedure enjoying wide application as a cosmetic treatment for skin wrinkles. Treatment success has been based on clinical assessments of skin smoothness. Skin lesions (1 cm2) created by one, two or three superimposed carbon-dioxide laser passes were placed on the backs of 28 'fuzzy' Harlan Sprague Dawley rats. The variable laser irradiation parameters included measured energies ranging from 112 to 387/pulse with pulse widths of 65 and 125 microseconds and a repetition rate of 8 Hz. The square, flat laser beam measured 3 mm2 at the focal point. The lesions were collected from 0 to 10 days after treatment for qualitative and quantitative histopathology. Thermal damage and treatment effect tended to increase in severity and, to a lesser extent, depth with increased delivery parameters. In acute lesions, the vacuolated and fragmented, desiccated and thermally coagulated epidermis was partially removed exposing the underlying thermally coagulated dermal collagen and cells. Epidermal and dermal necrosis and slough occurred between 24 to 72 hours after treatment. Epithelial regeneration originated from the adnexa and the lesion edges. Dermal fibrous scar formation began at 5 days below the regenerated epidermis and became more prominent at 7 and 10 days.

The impact of minimally invasive surgeries for the treatment of symptomatic benign prostatic hyperplasia on male sexual function: a systematic review.

PubMed

Frieben, Ryan W; Lin, Hao-Cheng; Hinh, Peter P; Berardinelli, Francesco; Canfield, Steven E; Wang, Run

2010-07-01

A systematic review of randomized controlled trials and cohort studies was conducted to evaluate data for the effects of minimally invasive procedures for treatment of symptomatic benign prostatic hyperplasia (BPH) on male sexual function. The studies searched were trials that enrolled men with symptomatic BPH who were treated with laser surgeries, transurethral microwave therapy (TUMT), transurethral needle ablation of the prostate (TUNA), transurethral ethanol ablation of the prostate (TEAP) and high-intensity frequency ultrasound (HIFU), in comparison with traditional transurethral resection of the prostate (TURP) or sham operations. A total of 72 studies were identified, of which 33 met the inclusion criteria. Of the 33 studies, 21 were concerned with laser surgeries, six with TUMT, four with TUNA and two with TEAP containing information regarding male sexual function. No study is available regarding the effect of HIFU for BPH on male sexual function. Our analysis shows that minimally invasive surgeries for BPH have comparable effects to those of TURP on male erectile function. Collectively, less than 15.4% or 15.2% of patients will have either decrease or increase, respectively, of erectile function after laser procedures, TUMT and TUNA. As observed with TURP, a high incidence of ejaculatory dysfunction (EjD) is common after treatment of BPH with holmium, potassium-titanyl-phosphate and thulium laser therapies (> 33.6%). TUMT, TUNA and neodymium:yttrium aluminum garnet visual laser ablation or interstitial laser coagulation for BPH has less incidence of EjD, but these procedures are considered less effective for BPH treatment when compared with TURP.

The impact of minimally invasive surgeries for the treatment of symptomatic benign prostatic hyperplasia on male sexual function: a systematic review

PubMed Central

Frieben, Ryan W.; Lin, Hao-Cheng; Hinh, Peter P.; Berardinelli, Francesco; Canfield, Steven E.; Wang, Run

2010-01-01

A systematic review of randomized controlled trials and cohort studies was conducted to evaluate data for the effects of minimally invasive procedures for treatment of symptomatic benign prostatic hyperplasia (BPH) on male sexual function. The studies searched were trials that enrolled men with symptomatic BPH who were treated with laser surgeries, transurethral microwave therapy (TUMT), transurethral needle ablation of the prostate (TUNA), transurethral ethanol ablation of the prostate (TEAP) and high-intensity frequency ultrasound (HIFU), in comparison with traditional transurethral resection of the prostate (TURP) or sham operations. A total of 72 studies were identified, of which 33 met the inclusion criteria. Of the 33 studies, 21 were concerned with laser surgeries, six with TUMT, four with TUNA and two with TEAP containing information regarding male sexual function. No study is available regarding the effect of HIFU for BPH on male sexual function. Our analysis shows that minimally invasive surgeries for BPH have comparable effects to those of TURP on male erectile function. Collectively, less than 15.4% or 15.2% of patients will have either decrease or increase, respectively, of erectile function after laser procedures, TUMT and TUNA. As observed with TURP, a high incidence of ejaculatory dysfunction (EjD) is common after treatment of BPH with holmium, potassium-titanyl-phosphate and thulium laser therapies (> 33.6%). TUMT, TUNA and neodymium:yttrium aluminum garnet visual laser ablation or interstitial laser coagulation for BPH has less incidence of EjD, but these procedures are considered less effective for BPH treatment when compared with TURP. PMID:20473318

The development of laser surgery and medicine in China

NASA Astrophysics Data System (ADS)

Chen, Mingzhe

2005-07-01

The first Chinese ruby laser was created in 1961 and it was adopted for the retina coagulation experiment in 1965. Since 1970's, lasers had been widely applied clinically including the diseases suitable to physical therapy or acupuncture. The Chinese HpD was first produced in 1981 and first case of PDT was treated using Chinese HpD and Chinese lasers in the same year. Its success brought attention establishing a research group supported by the government in 1982. A nationwide systemic research project on PDT was then carried out. The step taken for PDT also accelerated the development of various fields of laser medicine and surgery. Laser treatments had been commonly adopted in the clinics and hospitals for the diseases of the superficial lesions and the lesions can be reached by the endoscopes non-invasively in 1980's. Since 1990's, the interventional laser therapies adopted mainly were percutaneous laser angioplasty, laser treatments through laparoscope, thoracoscope, arthroscope, neuro-endoscope etc. Ultrasound guided percutaneous laser heat coagulation for small hepatic cancer revealed good results and ultrasound guided percutaneous PDT for advanced large liver cancer revealed unexpected results after five years follow-up. At present: There are more long-term follow-up patients in the clinical trial; more advanced commercial available lasers and new techniques are adopted. Since the popularization of scanning electron microscope, laser scanning confocal microscope, laser induced auto-fluorescence system, high sensitivity fluorescence microscopic imaging system etc. in the laboratories, the basic studies can be more advanced and some times, the sub-cellular level can be reached; ultra-structure histo-morphology and gene studies are involved. In dermatology, Q-switched Alexandrite laser and other Q-switched lasers are used mainly for the treatment of skin pigmentation and vascular diseases; pulsed dye laser, ultra-pulsed CO2 laser are used in resurfacing, facial acne scar, osmidrosis etc. For ophthalmology, excimer laser are used for myopia or hyperopia; argon green laser, krypton yellow laser are adopted in coagulation for retinal detachment and neovascularization etc. Lasers are often used for the canaliculoplasty in the lacrimal canal. Low level lasers had been used very often on the acupuncture points and for many chronic diseases. Intravascular low level laser irradiation adopting semiconductor lasers and He-Ne laser were reported to use for comatose patients, schizophrenia, vascular dementia, Alzeimer"s disease and coronary disease. Reports from laboratory studies in the field of low level laser demonstrated the stimulation effect on the cells and immunology system; inhibitory effect on proliferation; it improved the biomedical data in hemorrheology; promoted the spinal motor nerve cell function, axonal regeneration; increased epidermal Langerhams cell to improve the antigen function, increased myocardial capillary permeability. Intra-coronary low power red laser irradiation assisted coronary interventional therapy showed its prevention effect on restenosis. Studies about the effects of various kinds of lasers, their wavelength, power densities and doses on various kinds of tissues were reported.

New long-wavelength Nd:YAG laser at 1.44 micron: effect on brain.

PubMed

Martiniuk, R; Bauer, J A; McKean, J D; Tulip, J; Mielke, B W

1989-02-01

A wavelength-shifted Nd:YAG laser, tuned to coincide with the infrared absorption peak of water at 1.44 microns, was used to make lesions in normal rabbit brain. A total of 48 lesions were made with power up to 20 W, with energy up to 40 joules, and with two different spot sizes. These lesions were compared to lesions made with 1.06 microns radiation from an Nd:YAG laser under identical operating conditions. Measurements of blood-brain barrier damage and width, depth, and volume of tissue affected were obtained 30 minutes after placement of the lesions. It was found that 1.44-microns lesions produced photoevaporative tissue loss at the highest intensities used. The layer of coagulated tissue remaining after photovaporization had a mean thickness of 0.6 mm irrespective of the volume of tissue removed. There was no photovaporization in the 1.06-microns lesions. In addition, the amount of peripheral edema per unit volume of tissue coagulated was approximately half at the 1.44-microns wavelength. These findings suggest that the 1.44-microns Nd:YAG laser may be a useful surgical instrument since it combines the photoevaporative effect of the CO2 laser while maintaining the advantages of the conventional Nd:YAG laser (quartz fiber delivery and effective hemostasis).

Application of optical coherence tomography and high-frequency ultrasound imaging during noninvasive laser vasectomy

NASA Astrophysics Data System (ADS)

Cilip, Christopher M.; Allaf, Mohamad E.; Fried, Nathaniel M.

2012-04-01

A noninvasive approach to vasectomy may eliminate male fear of complications related to surgery and increase its acceptance. Noninvasive laser thermal occlusion of the canine vas deferens has recently been reported. Optical coherence tomography (OCT) and high-frequency ultrasound (HFUS) are compared for monitoring laser thermal coagulation of the vas in an acute canine model. Bilateral noninvasive laser coagulation of the vas was performed in six dogs (n=12 vasa) using a Ytterbium fiber laser wavelength of 1075 nm, incident power of 9.0 W, pulse duration of 500 ms, pulse rate of 1 Hz, and 3-mm-diameter spot. Cryogen spray cooling was used to prevent skin burns during the procedure. An OCT system with endoscopic probe and a HFUS system with 20-MHz transducer were used to image the vas immediately before and after the procedure. Vasa were then excised and processed for gross and histologic analysis for comparison with OCT and HFUS images. OCT provided high-resolution, superficial imaging of the compressed vas within the vas ring clamp, while HFUS provided deeper imaging of the vas held manually in the scrotal fold. Both OCT and high HFUS are promising imaging modalities for real-time confirmation of vas occlusion during noninvasive laser vasectomy.

Facet joint laser radiation: tissue effects of a new clinical laser application

NASA Astrophysics Data System (ADS)

Werkmann, Klaus; Thal, Dietmar R.

1996-01-01

Chronic unilateral and bilateral back pain with pseudoradicular symptoms, is a common clinical syndrome, which in many cases can be related to the facet joint syndrome. The pain is caused by mechanical affection of synovial and capsular nerve terminals. Therefore, current therapeutical attempts including physical therapy, intra-articular injection of local anesthetics and steroids and thermocoagulation of the facet joint with a thermocoagulator, are performed. We confirmed laser coagulation of the facet joint. Porcine cadaveric spines were treated immediately after death by intra-articular facet joint laser radiation. With the pulsed Nd:YAG laser (1064 nm) altogether 600 J were applied in three different places 4 mm apart at the top of the facet joint. The results showed that facet joint laser radiation leads to a small (about 1 - 2 mm diameter) lesion restricted to the facet joint cavity and its synovia. Histologically, we found a central carbonization zone and necrosis, including almost the whole cartilage and approximately 0.2 mm of the adjacent bone. These changes are similar to Nd:Yag-laser applications in other skeletal regions. It is suggested that these changes may lead to facet joint denervation by coagulation of the synovial nerve terminals. Cicatration of the laser lesion might cause ankylosis of this joint. In sum, facet joint laser radiation could be an alternative therapeutical tool for lower back pain of the facet joint syndrome type. Therefore, future clinical application of this technique seems to be very promising.

Role of laser therapy in benign prostate hyperplasia (BPH)

NASA Astrophysics Data System (ADS)

de Riese, Werner T.; Sharpe, Brent A.; Aronoff, David B.; Mittemeyer, Bernhard T.

2001-05-01

Benign prostatic hyperplasia (BPH) is a common disease in males older than 50 years of age. 75-80% of this population is considered to have some degree of BPH causing clinical symptoms and requiring urological treatment. Transurethral resection of the prostate (TUR-P) is currently the standard surgical treatment modality for BPH. In an attempt to minimize the need for hospitalization and the associated perioperative and postoperative morbidity, alternatives have been sought. Various types of laser techniques such as interstitial laser coagulation and side-firing technology have been proposed. Numerous studies have shown that laser procedures safely and effectively reduce the volume of the prostate. Intra- and postoperative bleeding are nearly unknown complications for laser procedures, whereas this is the most relevant complication for the TUR-P. Due to significant tissue edema after laser treatment, patients commonly show delayed time to void adequately and, therefore, catheter drainage is often necessary for 3 to 21 days. Retrograde ejaculation is reported to occur less (0- 10%) compared to TUR-P (greater than 60%). Urinary tract infections are very common after interstitial laser coagulation. Although not many long-term clinical data are available, various studies have shown that BPH patients improve in symptom score, flow rate and post-void residual up to 3 years after laser treatment. This paper presents a concise review of efficacy, advantages and disadvantages of the most frequently used laser techniques as well as the long-term clinical data compared to TUR-P.

Laser dosimetry planning tool for colonoscopic tumor resection

NASA Astrophysics Data System (ADS)

Pelayo-Fernández, M. L.; Fanjul-Vélez, F.; Salas-García, I.; Zverev, M.; Arce-Diego, J. L.

2016-03-01

Gastrointestinal tumoral pathologies are quite common nowadays. Diseases such as gastric antral vascular ectasia (GAVE) or actinic proctitis may require endoscopic surgery. Argon Plasma Coagulated (APC) or radiofrequency are usually employed. However, they present disadvantages, such as the reduced treated area, magnetic resonance incompatibility, or an uncontrolled ablation depth. Optical surgery could avoid these problems and contribute to a better and controlled treatment result, either ablative or coagulative, in a minimally invasive, non-contact and non-ionizing way. The treatment area could also be increased by adequate optical fiber probe design. In this work laser surgery is analyzed for resection of colonic tumors. A Monte Carlo model is employed to study optical propagation, and an optical ablation approach allows the estimation of the resected volume. The ablation approach is based on plasma-induced ablation, particularly taking into account the freeelectron density generated in the tissue by the pulsed optical source. Several wavelengths, radii and malignant tissue types are considered, either healthy, adenomatous or even coagulated tissues. Optimum source parameters as a function of tumor geometry can be estimated for treatment planning.

Incisional effects of 1940 nm thulium fiber laser on oral soft tissues

NASA Astrophysics Data System (ADS)

Güney, Melike; Tunç, Burcu; Gülsoy, Murat

2013-02-01

Lasers of different wavelengths are being used in oral surgery for incision and excision purposes with minimal bleeding and pain. Among these wavelengths, those close to 2μ yield more desirable results on oral soft tissue due to their strong absorption by water. The emission of 1940 nm Thulium fiber laser is well absorbed by water which makes it a promising tool for oral soft tissue surgery. This study was conducted to investigate the potential of thulium fiber laser as an incisional and excisional oral surgical tool. Ovine tongue has been used as the target tissue due to its similarities to human oral tissues. Laser light obtained from a 1940 nm Thulium fiber laser was applied in contact mode onto ovine tongue completely submerged in saline solution in vitro, via a 600)μm fiber moved with a velocity of 0.5 mm /s to form incisions. There were a total of 9 groups determined by the power (2,5-3- 3,5 W), and number of passes (1-3-5). The samples were stained with HE for microscopic evaluation of depth of ablation and extent of coagulation. The depth of incisions produced with 1940 nm Thulium fiber laser increased with increasing power and number of passes, however an increase in the width of the coagulation zone was also observed.

[Experimental study of brain lesions after combined coaxial exposure to high-peaked pulse wave form CO2 and Nd: YAG lasers on the brain].

PubMed

Tsuyumu, M; Verasques, G; Yamazaki, S; Kuroiwa, T; Suzuki, R; Takei, H; Suzuki, K; Inaba, Y

1985-04-01

The CO2 laser is useful for cutting and vaporization but not for coagulation and hemostasis. On the contrary, YAG laser is effective for coagulation and hemostasis but not for cutting. The purpose of this study is to examine the effect of the exposure of combined, coaxial CO2 and YAG laser on the animal brain to supplement the advantages and draw-backs of each other. To compare these results, each of non-combined pulse wave form CO2 and YAG lasers was employed separately. The lasers in this study were pulse wave form CO2 and YAG lasers, employed separately or simultaneously using 130 YZ of Nihon Infrared Industries Company. Japanese white rabbits were anesthetized with pentobarbital. Fronto-parietal burr holes were made, the dura was removed and then Evans blue solution was injected intravenously. The lasers were employed to the cerebral cortex without great vessels using a micromanipulator attached to the operative microscope with a distance of 30 cm. The spot size was 700 mu for CO2 laser and 1200 mu for YAG laser. The first experiment was to see the effect of nine combinations of simultaneous coaxial CO2 of 2, 4 and 8 watts and YAG lasers of 10, 20 and 40 watts, 1 sec on the brain. In the second experiment, also combining two lasers, the exposure time of YAG laser was elongated from 1 or 2 seconds into 2 or 4 seconds and the arrangement of powers was the same as that of the first experiment. The lesions were thus made in 18 different conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Local microcirculation disorders in uterus under laser tissue welding and their influence in the healing process

NASA Astrophysics Data System (ADS)

Kozlov, Valentine I.; Skobelkin, Oleg K.; Fatkullin, Ildar; Terman, Oleg A.; Chizhov, Gennadii; Gabidullina, Rushania

1994-12-01

To study the possibility of using Nd:YAG laser to weld the tissues of the uterus experiments in rats and dogs have been conducted. With the biomicroscopy and the laser Doppler flowmetry we have evaluated the microcirculation in the uterus wall under traditional suture and laser welding suture. As a model of the wound, the dissection of serosa and muscles of the organ wall have been used. In laser welding suture we have welded the zone of tissue about 1 mm3 with the laser (power density 270 W/cm2). Histological control has been fulfilled on various phases of the healing process. The investigation of the uterus wall demonstrates that there are zones of microcirculation disorders in tissues: (1) the zone of coagulation of microvessels and adjacent tissues (about 100 micrometers ); (2) the zone of stasis (150 - 200 micrometers ); (3) the zone of reactive-destructive changes of microvessels (300 micrometers ), (4) the zone of malfunctional microcirculatory changes (600 micrometers ). The coagulation of microvessels changes the character of inflammation and the healing process, decreases the exudation phase and the leucocyte infiltration of tissues, and accelerates the capillary growth. In contrast with traditional suture, in the case of laser welding suture the edema and hemorrhagic signs are less expressed. The complete restoration of microcirculation under laser welding suture has been observed by the fourteenth day of the healing process. Under the traditional suture method normalization of tissue nutritious blood flow has been achieved by 21 days.

Effects of Laser Physical Parameters on Lesion Size in Retinal Photocoagulation Surgery: Clinical OCT and Experimental Study

PubMed Central

Soleimani, A.; Rasta, S.H.; Banaei, T.; Asgharsharghi Bonab, A.

2017-01-01

Introduction: The aim of the present study was to determine burn intensity in retinal laser photocoagulation based on laser parameters; wavelength, power, beam size and pulse duration, using Optical Coherence Tomography (OCT), fundus camera, physical eye model and computer simulation in a clinical study. Materials and Methods: Participants were 10 adult patients between 50-80 years with proliferative diabetic retinopathy. A multicolor-photo coagulator with 532 nm green and 672 nm red for retina photocoagulation in diabetic retinopathy was used to investigate the participants. Lesion size was measured for spot sizes 50 and 100 μm, with 100 and 150 mW laser power, and pulse duration 50 and 100 ms by OCT. Artificial eye and Zemax-optical design software were used with the same laser parameters. Results: Appearance of OCT and fundus images showed direct relationship between retina burn size and lesion intensity with exposure time and power and also reverse relationship with laser spot size. Compared to red wavelength, burn size and lesion intensity increased in green wavelength. On the other hand, results from physical eye model were the same as clinical examination shown. Laser spot size in retina with Zemax simulation demonstrated that red wavelength was greater than green one. Conclusion: This study showed shorter pulses provide decrease in duration of laser surgery with significantly reduced pain. Results and calculations described in this article can help clinicians adjusting the required total coagulated area, the number of lesions and pattern density. PMID:29445713

Nd:YAG laser combined with gold nanorods for potential application in port-wine stains: an in vivo study.

PubMed

Xing, Linzhuang; Chen, Bin; Li, Dong; Wu, Wenjuan; Wang, Guoxiang

2017-11-01

Neodymium:yttrium aluminum garnet (Nd:YAG) lasers exhibit considerable potential for treating deeply buried port-wine stains. However, the application of Nd:YAG laser is limited by its weak absorption to blood. This in vivo study tested the efficacy and safety of utilizing thiol-terminated methoxypolyethylene glycol-modified gold nanorods (PEG-GNRs) to enhance the absorption of Nd:YAG laser to blood. Mouse mesentery and dorsal skinfold chamber (DSC) model were prepared to analyze the thermal responses of a single venule without anatomic structures, as well as blood vessels in the complex structure of the skin, to laser light. After the injection of 0.44 mg of PEG-GNRs, the required threshold density of laser energy for blood coagulation and complete vasoconstriction decreased from 24 to 18  J/cm2 in the mesentery model and from 36 to 31  J/cm2 in the DSC model. The laser pulse required for blood coagulation and complete vasoconstriction decreased by 67.75% and 62.25% on average in the mesentery model and by 67.55% and 54.45% on average in the DSC model. Histological and histochemical results confirmed that PEG-GNRs are nontoxic in the entire mouse life span. Therefore, combining PEG-GNRs with Nd:YAG laser may be effective and safe for inducing an obvious thermal response of blood vessels under low energy density and minimal pulse conditions. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Effects of Laser Physical Parameters on Lesion Size in Retinal Photocoagulation Surgery: Clinical OCT and Experimental Study.

PubMed

Soleimani, A; Rasta, S H; Banaei, T; Asgharsharghi Bonab, A

2017-12-01

The aim of the present study was to determine burn intensity in retinal laser photocoagulation based on laser parameters; wavelength, power, beam size and pulse duration, using Optical Coherence Tomography (OCT), fundus camera, physical eye model and computer simulation in a clinical study. Participants were 10 adult patients between 50-80 years with proliferative diabetic retinopathy. A multicolor-photo coagulator with 532 nm green and 672 nm red for retina photocoagulation in diabetic retinopathy was used to investigate the participants. Lesion size was measured for spot sizes 50 and 100 μm, with 100 and 150 mW laser power, and pulse duration 50 and 100 ms by OCT. Artificial eye and Zemax-optical design software were used with the same laser parameters. Appearance of OCT and fundus images showed direct relationship between retina burn size and lesion intensity with exposure time and power and also reverse relationship with laser spot size. Compared to red wavelength, burn size and lesion intensity increased in green wavelength. On the other hand, results from physical eye model were the same as clinical examination shown. Laser spot size in retina with Zemax simulation demonstrated that red wavelength was greater than green one. This study showed shorter pulses provide decrease in duration of laser surgery with significantly reduced pain. Results and calculations described in this article can help clinicians adjusting the required total coagulated area, the number of lesions and pattern density.

High-power potassium titanyl phosphate laser vaporization prostatectomy.

PubMed

Kuntzman, R S; Malek, R S; Barrett, D M

1998-08-01

In a search for potential therapeutic strategies for benign prostatic hyperplasia (BPH) that would be associated with less morbidity than transurethral resection of the prostate, various types of laser prostatectomy have been used. Although the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser allows performance of prostatectomy in an almost bloodless field and without absorption of irrigant, the remaining necrotic tissue causes bladder outlet obstruction and related symptoms for 5 to 7 days after treatment. In contrast, the potassium titanyl phosphate (KTP) laser has been found to vaporize tissue with minimal coagulation of the underlying structures. With use of the KTP laser, heat is concentrated into a small volume, the tissue is ablated by rapid vaporization of cellular water, and a 2-mm rim of coagulated tissue is left. After favorable results were obtained in studies of canine prostates and human cadavers, we implemented clinical use of 60-W KTP laser prostatectomy in selected patients. In 10 patients with symptomatic BPH who ranged in age from 52 to 80 years, outpatient KTP laser prostatectomy yielded significantly increased mean peak urinary flow rates (from 8.0 mL/s preoperatively to 19.4 mL/s within 24 hours after the procedure). No patient had hematuria, dysuria, or incontinence after removal of the catheter, and no patient required recatheterization. One patient, however, had urgency, and two other patients became febrile during the 24-hour observation period. Overall, KTP laser vaporization prostatectomy can provide immediate relief from obstructive symptoms of BPH and is not associated with dysuria.

Antenatal management of twin-twin transfusion syndrome and twin anemia-polycythemia sequence.

PubMed

Slaghekke, Femke; Zhao, Depeng P; Middeldorp, Johanna M; Klumper, Frans J; Haak, Monique C; Oepkes, Dick; Lopriore, Enrico

2016-08-01

Twin-twin transfusion syndrome (TTTS) and twin anemia polycythemia sequence (TAPS) are severe complications in monochorionic twin pregnancies associated with high mortality and morbidity risk if left untreated. Both diseases result from imbalanced inter-twin blood transfusion through placental vascular anastomoses. This review focuses on the differences in antenatal management between TTTS and TAPS. Expert commentary: The optimal management for TTTS is fetoscopic laser coagulation of the vascular anastomoses, preferably using the Solomon technique in which the whole vascular equator is coagulated. The Solomon technique is associated with a reduction of residual anastomosis and a reduction in post-operative complications. The optimal management for TAPS is not clear and includes expectant management, intra-uterine transfusion with or without partial exchange transfusion and fetoscopic laser surgery.

In vivo histological evaluation of non-insulated microneedle radiofrequency applicator with novel fractionated pulse mode.

PubMed

Harth, Yoram; Frank, Ido

2013-12-01

Microneedle radiofrequency is a novel method that allows non-thermal penetration of the epidermis followed by RF coagulation in selected depth of the dermis surrounded by zone of non-coagulative volumetric heating. The first generation of Microneedle RF applicators used insulated needles. These treatments were limited by a few factors, including low volume of dermal heating, lack of effect in the papillary dermis and pinpoint bleeding during the treatment. The system tested in this study (EndyMed PRO, Intensif applicator, EndyMed Medical, Cesarea, Israel) utilizes special extra sharp tapered non-insulated microneedles and a special pulse mode, allowing full coagulation during treatment and higher effective volume of dermal heat. After Ethics Committee approval, one female pig (Type Large white X Landrace, 34 Kg) was chosen for the study. The animal was anesthetized using Ketamine, Xylazin and Isofluran. The EndyMed PRO, Intensif applicator (was used for treatment with different needle depth penetration (1 mm-3.5 mm) and in multiple energy settings. Six mm punch biopsies were harvested for histological analysis at the following time points: immediately after the treatment, 4 days after the treatment and 14 days after the treatment. H&E and Masson-Trichrome stains were processed. Visual inspection of the treated skin, immediately after the treatment, revealed arrays of pinpoint erythematous papules surrounded by undamaged epidermal tissue. Treatment field showed no sign of bleeding. Mild to moderate Erythema and Edema developed a few minutes after the treatment, varying according to the total energy delivered. The histologies taken 4-day after therapy showed in all energy settings, dry micro crusts over the treatment zones, with full healing of epidermis. In the 14-day specimens there was a replacement of the crusts/debris by a normal looking stratum corneum with complete healing of epidermis and dermis. The current in vivo study confirms that the EndyMed PRO Intensif applicator effective and predictable tool to create cylindrical micro zones of coagulation in the papillary and reticular dermis with minimal damage to the epidermis. The histologies taken 4 days and 14 days after treatment show rapid epidermal renewal with predictable volume of coagulation in dermis related to the length of the needle and the power used. Coagulation of capillaries during treatment allows a dry treatment field. The predictability of the effect and minimal downtime may offer a significant advantage over treatments with ablative fractional lasers of insulated RF microneedles.

Laser probes for noninvasive coagulation of subsurface tissues

NASA Astrophysics Data System (ADS)

Chung, Chia-Chun; Permpongkosol, Sompol; Varkarakis, Ioannis M.; Lima, Guilherme; Franco, Nicholas; Hayman, Michael H.; Nicol, Theresa; Fried, Nathaniel M.

2006-02-01

Previous ex vivo tissue studies utilizing deep laser heating combined with contact cooling of the tissue surface produced noninvasive thermal destruction of subsurface tissue structures in skin and liver samples. This study describes the design and preliminary in vivo testing of two integrated laser/cooling probes for simultaneous Nd:YAG laser irradiation and sapphire contact cooling of liver and skin tissues in an in vivo, acute porcine model for potential use in laparoscopic and endoscopic surgery. Nd:YAG laser radiation with a wavelength of 1.06 μm, power of 20 W, 7.5-mm-diameter spot, 500-ms pulse length, and repetition rate of 0.625 Hz, was delivered to the tissue with a total irradiation time of 16 s. The tissue surface was continuously cooled with a sapphire plate maintained at -5 °C, and with pre- and post-ablation cooling times measuring 120 s and 30 s, resulting in a total operation time of 166 s per a lesion. Thermal lesions were created in liver and skin at a 1-mm depth below the tissue surface and with a 3-4 mm diameter. The laser parameters and lesion dimensions were comparable to previous ex vivo tissue studies. Preliminary in vivo animal studies demonstrate noninvasive creation of subsurface thermal lesions in tissue using Nd:YAG laser irradiation in conjunction with sapphire contact cooling. Chronic wound healing studies will be necessary to optimize the laser and cooling parameters. Potential clinical applications include endoscopic laser treatment of female stress urinary incontinence and thermal coagulation of early stage bladder tumors.

Histologic evaluation of laser lipolysis: pulsed 1064-nm Nd:YAG laser versus cw 980-nm diode laser.

PubMed

Mordon, Serge; Eymard-Maurin, Anne Françoise; Wassmer, Benjamin; Ringot, Jean

2007-01-01

The use of the laser as an auxiliary tool has refined the traditional technique for lipoplasty. During laser lipolysis, the interaction between the laser and the fat produced direct cellular destruction before the suction, reduced bleeding, and promoted skin tightening. This study sought to perform a comparative histologic evaluation of laser lipolysis with the pulsed 1064-nm Nd:YAG laser versus a continuous 980-nm diode laser. A pulsed 1064-nm Nd:YAG (Smart-Lipo; Deka, Italy) and a CW 980-nm diode laser (Pharaon, Osyris, France) were evaluated at different energy settings for lipolysis on the thighs of a fresh cadaver. The lasers were coupled to a 600-microm optical fiber inserted in a 1-mm diameter cannula. Biopsy specimens were taken on irradiated and non-irradiated areas. Hematoxylin-erythrosin-safran staining and immunostaining (anti-PS100 polyclonal antibody) were performed to identify fat tissue damage. In the absence of laser exposures (control specimens), cavities created by cannulation were seen; adipocytes were round in appearance and not deflated. At low energy settings, tumescent adipocytes were observed. At higher energy settings, cytoplasmic retraction, disruption of membranes, and heat-coagulated collagen fibers were noted; coagulated blood cells were also present. For the highest energy settings, carbonization of fat tissue involving fibers and membranes was clearly seen. For equivalent energy settings, 1064-nm and 980-nm wavelengths gave similar histologic results. Laser lipolysis is a relatively new technique that is still under development. Our histologic findings suggest several positive benefits of the laser, including skin retraction and a reduction in intraoperative bleeding. The interaction of the laser with the tissue is similar at 980 nm and 1064 nm with the same energy settings. Because higher volumes of fat are removed with higher total energy, a high-power 980-nm diode laser could offer an interesting alternative to the 1064-nm Nd:YAG laser.

Versatility of erbium YAG laser: from fractional skin rejuvenation to full-field skin resurfacing.

PubMed

Holcomb, J David

2011-05-01

For the laser surgeon, the Er-YAG laser is an invaluable tool that delivers unsurpassed ablation efficiency, and with appropriate functionality (quasi long-pulse feature) provides sufficient tissue coagulation to remodel deep rhytids. As such, the 2940-nm wavelength is well suited for routine laser skin rejuvenation in full-field, fractional, and point-beam modes with additional benefits, including applicability to diverse skin types, short healing times, and a low likelihood of energy-related complications. Copyright © 2011 Elsevier Inc. All rights reserved.

First collaborative experience with thulium laser ablation of localized upper urinary tract urothelial tumors using retrograde intra-renal surgery.

PubMed

Defidio, Lorenzo; De Dominicis, Mauro; Di Gianfrancesco, Luca; Fuchs, Gerhard; Patel, Anup

2011-09-01

Thulium laser ablation (TLA) outcomes with blinded performance evaluation after retrograde intra-renal surgical (RIRS) treatment of upper urinary tract transitional cell carcinomas (UUT-TCC). A UUT-TCC patient cohort undergoing RIRS-TLA by an international endoscopic surgical collaboration in a European center (April 2005-July 2009), underwent outcomes evaluation. All 4 surgeons were blinded and independently scored both TLA and Holmium:YAG laser ablation performance aspects annually using a Likert scoring system (0-10). All patients (n = 59, median age 66 years, 9 with solitary kidney) had complete UUT inspection. Presenting lesion(s) were intra-renal (n = 30, 51%), ureteral (n = 13, 22%), and combined (n = 16, 27%). Single-stage TLA sufficed in 81.4% (tumors < 1.5 cm). Significant recurrence free survival differences occurred according to primary tumor size >/< 1.5 cm and multi-focality, but location made no difference. Median Likert scores were i) fiber-tip stability --5.5/8.75, p = 0.016; ii) reduced bleeding--5/8.5, p = 0.004; iii)fiber-tip precision--5.5/8.5, p = 0.003; iv) mucosal perforation reduction--3.5/7.5, p = 0.001; v) ablation efficiency tumors < 1.5 cm--6/9, p = 0.017; tumors > 1.5 cm--6.75/6.75, p = 1, and vi) overall efficiency--6/7.5, p = 0.09, for Holmium:YAG and TLA, respectively. The Thulium laser delivered non-inferior recurrence free survival to RIRS-UUT-TCC Holmium:YAG laser ablation, but better median parameter performance scores in fiber-tip stability, precision, reduced bleeding and mucosal perforation reduction in expert ratings. Despite improved photothermal coagulation, and endo-visualization for tumors < 1.5 cm, both ablation and overall efficiency remained challenging for larger tumors with both existing laser technologies.

Contact diode laser application through a fiberoptic cutting tip.

PubMed

Peyman, G A; Cruz, S A; Ruiz-Lapuente, C

1991-01-01

We applied diode laser energy through a fiberoptic probe to cut ocular structures. The diameter of the probe's tip was 100 microns. The amount of energy used for cutting the lid, the cornea, or for perforation of the glove was 2.5 watts in the continuous mode. The incised border demonstrated coagulation into the healthy tissue ranging from 10 to 50 microns.

21 CFR 874.4490 - Argon laser for otology, rhinology, and laryngology.

Code of Federal Regulations, 2014 CFR

2014-04-01

... HUMAN SERVICES (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Surgical Devices § 874.4490... used for the purpose of coagulating and vaporizing soft and fibrous tissues, including osseous tissue...

21 CFR 874.4490 - Argon laser for otology, rhinology, and laryngology.

Code of Federal Regulations, 2012 CFR

2012-04-01

... HUMAN SERVICES (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Surgical Devices § 874.4490... used for the purpose of coagulating and vaporizing soft and fibrous tissues, including osseous tissue...

21 CFR 874.4490 - Argon laser for otology, rhinology, and laryngology.

Code of Federal Regulations, 2013 CFR

2013-04-01

... HUMAN SERVICES (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Surgical Devices § 874.4490... used for the purpose of coagulating and vaporizing soft and fibrous tissues, including osseous tissue...

Diagnostic blood-flow monitoring during therapeutic interventions using color Doppler optical coherence tomography

NASA Astrophysics Data System (ADS)

Yazdanfar, Siavash; Kulkarni, Manish D.; Wong, Richard C. K.; Sivak, Michael J., Jr.; Willis, Joseph; Barton, Jennifer K.; Welch, Ashley J.; Izatt, Joseph A.

1998-04-01

A recently developed modality for blood flow measurement holds high promise in the management of bleeding ulcers. Color Doppler optical coherence tomography (CDOCT) uses low- coherence interferometry and digital signal processing to obtain precise localization of tissue microstructure simultaneous with bi-directional quantitation of blood flow. We discuss CDOCT as a diagnostic tool in the management of bleeding gastrointestinal lesions. Common treatments for bleeding ulcers include local injection of a vasoconstrictor, coagulation of blood via thermal contact or laser treatment, and necrosis of surrounding tissue with a sclerosant. We implemented these procedures in a rat dorsal skin flap model, and acquired CDOCT images before and after treatment. In these studies, CDOCT succeeded in identifying cessation of flow before it could be determined visually. Hence, we demonstrate the diagnostic capabilities of CDOCT in the regulation of bleeding in micron-scale vessels.

Healing of rat mouth mucosa after irradiation with CO2, Nd:YAG, and CO2-Nd:YAG combination lasers.

PubMed

Luomanen, M; Rauhamaa-Mäkinen, R; Meurman, J H; Kosloff, T; Tiitta, O

1994-08-01

The healing process of wounds made by a combination laser was studied in 90 rats. The laser system enabled both separate and combined use of CO2 and Nd:YAG laser irradiations. The laser wounds and the control excision wounds made by alligator forceps appeared on both sides of the tongue. Specimens from the wound sites were taken immediately, 6 h, and 1, 2, 4, 7, 11, 21, 28, and 42 days after surgery. The wound-healing process was studied by macroscopic evaluation before preparing the specimens for light microscopy. Some differences were noted in the wound-healing process among the three groups into which the experimental animals were divided. Tissue coagulation damage was most extensive in the Nd:YAG laser sites, where it was observed in its full extent 4 days after surgery. Epithelial cells were seen to begin to proliferate in all the wounds 6 h after surgery. Re-epithelialization was completed by between 7 (CO2) and 21 days (Nd:YAG) at all the wound sites. The inflammatory cell infiltration was more prominent in the Nd:YAG and the CO2-Nd:YAG combination laser wounds than in the CO2 and excision wounds during healing. Tissue regeneration occurred faster with less contraction in the combination CO2-Nd:YAG wounds than in Nd:YAG wounds. The best macroscopic healing result was seen in the CO2 wound sites. The combination laser was effective both at cutting and at coagulating tissue. Combining the CO2 and Nd:YAG laser irradiation into one beam resulted in a greater incision depth than what could have been expected from using the two lasers separately.

Fetoscopic laser ablation of placental anastomoses in twin-twin transfusion syndrome using 'Solomon technique'.

PubMed

Ruano, R; Rodo, C; Peiro, J L; Shamshirsaz, A A; Haeri, S; Nomura, M L; Salustiano, E M A; de Andrade, K K; Sangi-Haghpeykar, H; Carreras, E; Belfort, M A

2013-10-01

To document perinatal outcomes following use of the 'Solomon technique' in the selective photocoagulation of placental anastomoses for severe twin-twin transfusion syndrome (TTTS). Between January 2010 and July 2012, data were collected from 102 consecutive monochorionic twin pregnancies complicated by severe TTTS that underwent fetoscopic laser ablation at four different centers. We compared outcomes between subjects that underwent selective laser coagulation using the Solomon technique (cases) and those that underwent selective laser coagulation without this procedure (controls). Of the 102 pregnancies examined, 26 (25.5%) underwent the Solomon technique and 76 (74.5%) did not. Of the 204 fetuses, 139 (68.1%) survived up to 30 days of age. At least one twin survived in 82 (80.4%) pregnancies and both twins survived in 57 (55.9%) pregnancies. When compared with the control group, the Solomon-technique group had a significantly higher survival rate for both twins (84.6 vs 46.1%; P < 0.01) and a higher overall neonatal survival rate (45/52 (86.5%) vs 94/152 (61.8%); P < 0.01). Use of the Solomon technique remained independently associated with dual twin survival (adjusted odds ratio (aOR), 11.35 (95% CI, 3.11-53.14); P = 0.0007) and overall neonatal survival rate (aOR, 4.65 (95% CI, 1.59-13.62); P = 0.005) on multivariable analysis. There were no cases of recurrent TTTS or twin anemia-polycythemia sequence (TAPS) in the Solomon-technique group. Use of the Solomon technique following selective laser coagulation of placental anastomoses appears to improve twin survival and may reduce the risk of recurrent TTTS and TAPS. Our data support the idea of performing a randomized controlled trial to evaluate the effectiveness of the Solomon technique. Copyright © 2013 ISUOG. Published by John Wiley & Sons Ltd.

Contact diode laser: high power application through fiberoptic cutting tips.

PubMed

Wafapoor, H; Peyman, G A; Moritera, T

1994-01-01

Diode laser energy has been applied through a fiberoptic probe using a power setting of 2.5 watts (W) in the continuous mode. In this study we employed high-power diode laser energy (4 to 12 W, continuous wave) to incise ocular tissue through a fiberoptic probe using 100 microns and 300 microns tips. The retina was photocoagulated with a 300 microns orb tip. No bleeding occurred at the incision sites. Histologic evaluation revealed coagulation into the healthy tissue ranging from 10 to 50 microns.

Holmium:YAG and erbium:YAG laser interaction with hard and soft tissue

NASA Astrophysics Data System (ADS)

Charlton, Andrew; Dickinson, Mark R.; King, Terence A.; Freemont, Anthony J.

1991-06-01

The holmium YAG and erbium YAG lasers operating at 2.1 micrometers and 2.9 micrometers respectively, are the subject of great interest for various medical applications. The interaction of both these pulsed lasers with biological tissue involves absorption of the radiation by water leading to rapid heating and ablation, however the different absorption coefficients at these two wavelengths give rise to different ablation efficiencies and haemostatic properties for the two lasers. It is this cut/seal ratio that determines for which medical applications each of these lasers is most suited. The lasers were used to produce incisions in various tissues by translating the tissue at fixed speed beneath a focused laser beam. The laser energy density was varied between 100 and 500 J/cm2 and the lasers were operated at 2 Hz. After irradiation the tissues were fixed in formalin, processed routinely into paraffin wax, sectioned at 5 micrometers and stained with haemotoxylin and eosin. This allowed the dimensions of the incisions to be measured, as well as the depth of coagulative denatured tissue surrounding each incision. In this way the cut/seal ratio was determined for both the holmium YAG and erbium YAG laser in a range of hard and soft tissues. Results show that the latent heat of ablation for the holmium YAG laser interacting with soft tissue varies between 20-50 kJ/cm3, almost an order of magnitude larger than with the erbium YAG laser. Furthermore, the depth of coagulative necrosis with holmium YAG extends 100-400 micrometers , compared with 10-30 micrometers for erbium YAG. The two interactions clearly lead to vastly different results suggesting that the holmium YAG laser is suitable for producing lesions in highly vascular tissue where haemostasis is important, whereas the erbium YAG laser is better suited to avascular tissue requiring large depths of incision.

[Retinal vessels before and after photocoagulation in diabetic retinopathy. Determining the diameter using digitized color fundus slides].

PubMed

Remky, A; Arend, O; Beausencourt, E; Elsner, A E; Bertram, B

1996-01-01

Retinal vessel diameter is an important parameter in blood flow analysis. Despite modern digital image technology, most clinical studies investigate diameters subjectively using projected fundus slides or negatives. In the present study we used a technique to examine vessel diameters by digital image analysis of color fundus slides. We investigated in a retrospective manner diameter changes in twenty diabetic patients before and after panretinal laser coagulation. Color fundus slides were digitized by a new high resolution scanning device. The resulting images consisted in three channels (red, green, blue). Since vessel contrast was the highest in the green channel, we assessed grey value profiles perpendicular to the vessels in the green channel. Diameters were measured at the half-height of the profile. After panretinal laser coagulation, average venous diameter was decreased, whereas arterial diameter remained unchanged. There was no significant relation between the diameter change and the number of laser burns or the presence of neovascularization. Splitting digitized images into color planes enables objective measurements of retinal diameters in conventional color slides.

Clinical studies of Nd:YAG laser and Chinese herbal medicine in treatment of patients with tinea unguium

NASA Astrophysics Data System (ADS)

Dan, Ming-bing; Chen, Nanjin; Chao, Changyuan

1993-03-01

Forty-seven patients with tinea unguium and 110 tinea unguium, proven bacteriologically and pathologically, were treated with an Nd:YAG laser and Chinese herbal medicine, after which they were analyzed. All patients were adult men and women. The duration of illness varied from 1 to 10 years. The patients were treated with Nd:YAG laser wavelength 1.06 micrometers and the ending output power 500 w/cm2. The diseased nail was removed by laser scanning or cauterization, charring, gasification and coagulation layer by layer until the nail matrix was exposed, and then it was bandaged with a small amount of Chinese herbal medicine. The cure rate is 80.0%. The tinea unguium infection rate of pars super finialis is very high in cities, accounting for more than 80% of the cases among the population. It influences patients' lives and finger appearance. However, removal of tinea unguium with Nd:YAG laser cauterization and coagulation is simple, painless, and does not require disinfection. Also, the reoccurrence rate is low. Treatment of tinea unguium is intractable. Oral administration of griseofulvin and ketoconazole are not completely satisfactory and hardly persist for a long-term treatment course. Moreover, long-term administration of these drugs might produce serious side effects such as renal injuries, leukopenia, psychosis, etc. Thus, we conclude from this data that Nd:YAG laser and Chinese herbal medicine are an effective treatment for hypertrophic scarand kiloid and valuable for further investigations.

Measurement of the coagulation dynamics of bovine liver using the modified microscopic Beer-Lambert law.

PubMed

Terenji, Albert; Willmann, Stefan; Osterholz, Jens; Hering, Peter; Schwarzmaier, Hans-Joachim

2005-06-01

During heating, the optical properties of biological tissues change with the coagulation state. In this study, we propose a technique, which uses these changes to monitor the coagulation process during laser-induced interstitial thermotherapy (LITT). Untreated and coagulated (water bath, temperatures between 35 degrees C and 90 degrees C for 20 minutes.) samples of bovine liver tissue were examined using a Nd:YAG (lambda = 1064 nm) frequency-domain reflectance spectrometer. We determined the time integrated intensities (I(DC)) and the phase shifts (Phi) of the photon density waves after migration through the tissue. From these measured quantities, the time of flight (TOF) of the photons and the absorption coefficients of the samples were derived using the modified microscopic Beer-Lambert law. The absorption coefficients of the liver samples decreased significantly with the temperature in the range between 50 degrees C and 70 degrees C. At the same time, the TOF of the investigated photos was found increased indicating an increased scattering. The coagulation dynamics could be well described using the Arrhenius formalism with the activation energy of 106 kJ/mol and the frequency factor of 1.59 x 10(13)/second. Frequency-domain reflectance spectroscopy in combination with the modified microscopic Beer-Lambert (MBL) is suitable to measure heat induced changes in the absorption and scattering properties of bovine liver in vitro. The technique may be used to monitor the coagulation dynamics during local thermo-coagulation in vivo. Copyright 2005 Wiley-Liss, Inc.

Photoselective laser ablation of the prostate: a review of the current 2015 tissue ablation options.

PubMed

Tholomier, Côme; Valdivieso, Roger; Hueber, Pierre-Alain; Zorn, Kevin C

2015-10-01

Transurethral resection of the prostate (TURP) is still considered the gold standard to treat benign prostatic hyperplasia (BPH). However, photoselective vaporization of the prostate (PVP) has gained widespread acceptance as an alternative option requiring preoperative patient selection. Four laser systems are currently in use: holmium, thulium, diode and GreenLight. The goal of this article is to review the physics and the basics behind laser prostatectomies, as well as to present the most current literature concerning the results, advantages, disadvantages and international recommendations for each vaporization procedure. Holmium laser ablation of the prostate (HoLAP) and GreenLight photoselective vaporization of the prostate are an alternative to TURP for small to medium-sized prostates, providing equivalent efficacy and safety. GreenLight is also safe and effective in large-sized prostates and especially beneficial in anti-coagulated individuals compared to TURP. Thulium vaporization of the prostate (ThuVAP) and diode vaporization both require additional randomized trials and long term studies before conclusion is made, despite promising initial results. Diode vaporization provides the best hemostasis overall, but at the cost of increased complication and re-treatment rate, and thus is not recommended except in severely anti-coagulated patients. Laser vaporization is a safe and effective alternative to TURP in the treatment of benign prostatic hyperplasia (BPH) for carefully selected patients. However, further research is still needed to assess the durability of each technology.

Variable-focus side-firing endoscopic device

NASA Astrophysics Data System (ADS)

Lemberg, Vladimir G.; Black, Michael

1996-05-01

Conventional side-firing fiber technology exhibits performance limitations and utilizes expensive single-use only devices which often require multiple fibers for laser prostatectomy. Another limitation of existing side-firing fiber technology is its inability to focus the beam to create incisions for urologic applications such as laser TURP (transurethral resectional prostatectomy), tumor necrosis, lithotripsy, genital warts, and photodynamic therapy. Newly introduced variable-focus side-firing endoscopic device utilizes either one or two lenses and a mirror, onto a single cylinder of molded glass. The laser beam exits the optical fiber, passes through the lens, strikes the cylindrical mirror, and traverses the cylindrical surface. Depending on the design, the laser beam is reflected at the angles ranging from 30 degrees to 120 degrees out of the cylindrical lens. A second lens can be formed onto the side of the cylindrical surface at the beam's exit point. Another advantage of the innovative side-firing device is its capability to provide versatile matching to multiple laser wavelengths from 360 nm to 2.5 microns, and achieve power densities great enough to perform vaporization, incision and coagulation of tissue. Precise focusing of the laser beam results in reduced tissue necrosis of surrounding the treatment area as well as in decreased laser radiation back-scattering. Surgeons can very the focus by adjusting the distance from the tip to the target area. The variable focus side-firing device provides a focused beam at the range of 1.0 to 1.5 mm, for incision. Outside this range, it produces a defocused beam for coagulation.

Diode Laser Ear Piercing: A Novel Technique.

PubMed

Suseela, Bibilash Babu; Babu, Preethitha; Chittoria, Ravi Kumar; Mohapatra, Devi Prasad

2016-01-01

Earlobe piercing is a common office room procedure done by a plastic surgeon. Various methods of ear piercing have been described. In this article, we describe a novel method of laser ear piercing using the diode laser. An 18-year-old female patient underwent an ear piercing using a diode laser with a power of 2.0 W in continuous mode after topical local anaesthetic and pre-cooling. The diode laser was fast, safe, easy to use and highly effective way of ear piercing. The advantages we noticed while using the diode laser over conventional methods were more precision, minimal trauma with less chances of hypertrophy and keloids, no bleeding with coagulation effect of laser, less time taken compared to conventional method and less chance of infection due to thermal heat effect of laser.

[Experimental liver and kidney surgery with CO2, CO, holmium, and neodym lasers. Cutting effect, hemostasis, histopathology, and healing (author's transl)].

PubMed

Karbe, E; Königsmann, G; Beck, R

1980-01-01

Various laser devices (CO2, CO, Nd: YAG, and holmium: YAG lasers) have been used on pig livers and on dog kidneys for comparison with conventional surgical instruments (electroscalpel, cryoscalpel, and scalpel). CO2 and CO lasers caused the least tissue damage, followed by the holmium laser; severe damage was caused by the Nd: YAG laser. The order was reverse for coagulative effect. The conventional reference instruments showed a weaker hemostatic effect. Surfaces cut by laser healed in four to eight weeks without complications. Remnants of charred tissue in various quantities could still be detected after eight weeks in all cases where CO2, CO, and Nd: YAG lasers had been used. This obviously did not affect scar formation.

Glial reactions to argon laser photocoagulation injury in rabbit and rat retinas

NASA Astrophysics Data System (ADS)

Humphrey, Martin F.; Chu, Yi; Sharp, Claudia; Moore, Stephen; Mann, Krishna; Rakoczy, Piroska; Constable, Ian J.

1996-04-01

Argon laser photocoagulation is a standard and effective clinical technique for a variety of disease conditions. However there is evidence that coagulation produces more widespread alterations in the retina than the local scarring at the injury site. For example, in diabetic retinopathy multiple photocoagulations in the retinal periphery can control blood vessel growth in the central retina. Therefore we have studied the changes in retinal glial cells following photocoagulation using immunocytochemical techniques with an emphasis on the spread of cellular reactions by using whole, flatmounted retinal preparations. Muller glial cells do not normally express the cytoskeletal protein GFAP (glial fibrillary acidic protein) but do so after a variety of injuries. We found that there is a very widespread expression of GFAP by Muller cells even after very focal coagulations and that this persists for 1 - 1.5 months after coagulation. The microglial cells are primed to react to injury and can release very powerful effector molecules and we therefore also examined the microglial reaction to see whether it correlated with the Muller cell reaction. However, we found that the microglial response, in terms of anatomical changes, was very focally confined to regions of direct cellular injury. We also examined MHC II expression to see whether microglia expressed this activity related protein without anatomical changes but we found no evidence of wide spread changes. In summary we find that inflammatory reactions are very localized after coagulation but the macroglial changes are more widespread and therefore the distant effects of photocoagulation may be more related to macroglial reactions.

Diode-pumped solid state green laser for ophthalmologic application

NASA Astrophysics Data System (ADS)

Eno, Taizo; Goto, Yoshiaki; Momiuchi, Masayuki

2002-10-01

We have developed diode pumped solid state green laser suitable for ophthalmologic applications. Beam parameters were designed by considering the coagulation system. We have lowered the beam quality to multi transverse and longitudinal mode on purpose to improve the speckle noise of the slit lamp output beam. The beam profile shows homogeneous intensity and it is very useful for ophthalmologic application. End pumping and short cavity configuration made it possible.

Towards in vivo laser coagulation and concurrent optical coherence tomography through double-clad fiber devices

NASA Astrophysics Data System (ADS)

Beaudette, Kathy; Lo, William; Villiger, Martin; Shishkov, Milen; Godbout, Nicolas; Bouma, Brett E.; Boudoux, Caroline

2016-03-01

There is a strong clinical need for an optical coherence tomography (OCT) system capable of delivering concurrent coagulation light enabling image-guided dynamic laser marking for targeted collection of biopsies, as opposed to a random sampling, to reduce false-negative findings. Here, we present a system based on double-clad fiber (DCF) capable of delivering pulsed laser light through the inner cladding while performing OCT through the core. A previously clinically validated commercial OCT system (NVisionVLE, Ninepoint Medical) was adapted to enable in vivo esophageal image-guided dynamic laser marking. An optimized DCF coupler was implemented into the system to couple both modalities into the DCF. A DCF-based rotary joint was used to couple light to the spinning DCF-based catheter for helical scanning. DCF-based OCT catheters, providing a beam waist diameter of 62μm at a working distance of 9.3mm, for use with a 17-mm diameter balloon sheath, were used for ex vivo imaging of a swine esophagus. Imaging results using the DCF-based clinical system show an image quality comparable with a conventional system with minimal crosstalk-induced artifacts. To further optimize DCF catheter optical design in order to achieve single-pulse marking, a Zemax model of the DCF output and its validation are presented.

Improving the therapeutic window of retinal photocoagulation by spatial and temporal modulation of the laser beam

NASA Astrophysics Data System (ADS)

Sramek, Christopher; Leung, Loh-Shan; Leng, Theodore; Brown, Jefferson; Paulus, Yannis M.; Schuele, Georg; Palanker, Daniel

2011-02-01

Decreasing the pulse duration helps confine damage, shorten treatment time, and minimize pain during retinal photocoagulation. However, the safe therapeutic window (TW), the ratio of threshold powers for thermomechanical rupture of Bruch's membrane and mild coagulation, also decreases with shorter exposures. Two potential approaches toward increasing TW are investigated: (a) decreasing the central irradiance of the laser beam and (b) temporally modulating the pulse. An annular beam with adjustable central irradiance was created by coupling a 532-nm laser into a 200-μm core multimode optical fiber at a 4-7 deg angle to normal incidence. Pulse shapes were optimized using a computational model, and a waveform generator was used to drive a PASCAL photocoagulator (532 nm), producing modulated laser pulses. Acute thresholds for mild coagulation and rupture were measured in Dutch-Belted rabbit in vivo with an annular beam (154-163 μm retinal diameter) and modulated pulse (132 μm, uniform irradiance ``flat-top'' beam) with 2-50 ms pulse durations. Thresholds with conventional constant-power pulse and a flat-top beam were also determined. Both annular beam and modulated pulse provided a 28% increase in TW at 10-ms duration, affording the same TW as 20-ms pulses with conventional parameters.

Utility and safety of the flexible-fiber CO2 laser in endoscopic endonasal transsphenoidal surgery.

PubMed

Jayarao, Mayur; Devaiah, Anand K; Chin, Lawrence S

2011-01-01

This study sought to report on the utility and safety of the flexible-fiber CO2 laser in endoscopic endonasal transsphenoidal surgery. A retrospective chart review identified 16 patients who underwent laser-assisted transsphenoidal surgery. All tumor pathology types were considered. Results were assessed based on hormone status, tumor size, pathology, complications, and resection rates. Sixteen pituitary lesions (pituitary adenomas, 12; Rathke cleft cyst, 2; pituitary cyst and craniopharyngioma, 1 each) with an average size of 22.7 mm were identified by radiographic and pathologic criteria. All patients underwent flexible-fiber CO2 laser-assisted endoscopic endonasal transsphenoidal surgery. Of the adenomas, 8 were nonsecreting and 4 were secreting (3 prolactinomas and 1 ACTH secreting). Gross total resection was achieved in 7 of 16 patients (43.75%) with hormone remission in all patients (100%) after a mean follow-up of 19.3 months. Postoperative complications occurred in 3 patients (18.75%): 2 patients developed transient diabetes insipidus (DI) and 1 developed a CSF leak requiring surgical repair. Five patients (31.25%) underwent postoperative radiation to the residual lesions. We found that CO2-laser-assisted endoscopic endonasal transsphenoidal surgery for sellar tumors is a minimally invasive approach using a tool that is quick and effective at cutting and coagulation. The surgery has a low rate of complication, and no laser-related complications were encountered. The laser fiber allows the surgeon to safely cut and coagulate without the line-of-sight problems encountered with conventional CO2 lasers. Further studies are recommended to further define its role in endoscopic endonasal sellar surgery. Copyright © 2011 Elsevier Inc. All rights reserved.

Coagulative interstitial laser-induced thermotherapy of benign prostatic hyperplasia: online imaging with a T2-weighted fast spin-echo MR sequence--experience in six patients.

PubMed

Mueller-Lisse, U G; Thoma, M; Faber, S; Heuck, A F; Muschter, R; Schneede, P; Weninger, E; Hofstetter, A G; Reiser, M F

1999-02-01

To determine if hypointense lesions clearly outline on T2-weighted fast spin-echo (SE) magnetic resonance (MR) images obtained during coagulative interstitial laser-induced thermotherapy (LITT) of a prostate with benign hyperplasia. In six patients with benign prostatic hyperplasia (BPH), 12 LITT treatments were followed online with repetitive axial T2-weighted fast SE imaging (repetition time, 3,700 msec; echo time, 138 msec; acquisition time, 19 seconds). Development, time course, correlation with interstitial tissue temperature, and diameters of hypointense lesions around the laser diffusor tip were investigated. Lesion diameters on T2-weighted images acquired during LITT were compared with diameters of final lesions on T2-weighted images and unperfused lesions on enhanced T1-weighted SE images obtained at the end of therapy. Hypointense lesions developed within 20-40 seconds of LITT. Average correlation coefficients between interstitial temperature development and signal intensity development were 0.92 during LITT and 0.90 after LITT. Regression slopes were significantly steeper during LITT (0.67% signal intensity change per degree Celsius) than after LITT (0.47% per degree Celsius; P = .038). Lesions remained visible after LITT for all procedures. Average maximum diameters of lesions were 1-3 mm larger during LITT than after LITT (P = .0006-.019). Repetitive T2-weighted fast SE MR imaging during interstitial coagulative LITT of BPH demonstrates the development of permanent hypointense prostate lesions. However, posttherapeutic lesion diameters tend to be overestimated during LITT.

Solomon Technique Versus Selective Coagulation for Twin-Twin Transfusion Syndrome.

PubMed

Slaghekke, Femke; Oepkes, Dick

2016-06-01

Monochorionic twin pregnancies can be complicated by twin-to-twin transfusion syndrome (TTTS). The best treatment option for TTTS is fetoscopic laser coagulation of the vascular anastomoses between donor and recipient. After laser therapy, up to 33% residual anastomoses were seen. These residual anastomoses can cause twin anemia polycythemia sequence (TAPS) and recurrent TTTS. In order to reduce the number of residual anastomoses and their complications, a new technique, the Solomon technique, where the whole vascular equator will be coagulated, was introduced. The Solomon technique showed a reduction of recurrent TTS compared to the selective technique. The incidence of recurrent TTTS after the Solomon technique ranged from 0% to 3.9% compared to 5.3-8.5% after the selective technique. The incidence of TAPS after the Solomon technique ranged from 0% to 2.9% compared to 4.2-15.6% after the selective technique. The Solomon technique may improve dual survival rates ranging from 64% to 85% compared to 46-76% for the selective technique. There was no difference reported in procedure-related complications such as intrauterine infection and preterm premature rupture of membranes. The Solomon technique significantly reduced the incidence of TAPS and recurrent TTTS and may improve survival and neonatal outcome, without identifiable adverse outcome or complications; therefore, the Solomon technique is recommended for the treatment of TTTS.

Review on toxicology of aerosols produced during medical laser treatment or electrosurgery

NASA Astrophysics Data System (ADS)

Weber, Lothar W.; Meier, Thomas H.

1994-02-01

Medical laser treatment enlarged its application in recent years in an explosive way. By a given distance to the patient the laser surgeon can cut, coagulate, or evaporate human tissue in a very distinct manner. Due to the mainly thermal interaction of the laser light with the irradiated tissue it may be heated up to pyrolysis conditions. By pyrolysis of human tissue degradation products are generated, which may be harmful. Chemical substances and particles formed of tissue could be toxic, cancerogenic or irritant to skin and airways or after uptake. Special hazards of human laser plume in the health care environment may result from infectious viruses, bacterias, parasites, spread tumor cells and DNA fragments.

Effects of Er:YAG laser irradiation on human cartilage

NASA Astrophysics Data System (ADS)

Glinkowski, Wojciech; Brzozowska, Malgorzata; Ciszek, Bogdan; Rowinski, Jan; Strek, Wieslaw

1996-03-01

Irradiation of the hyaline or fibrous cartilage excised from the body of a human cadaver with Er:YAG laser beam, single pulse with a dose of 1 J, produces a crater with a depth of approximately 500 micrometers and a diameter varying from 5 to 300 micrometers. Histological examination has revealed that the laser-made craters were surrounded by a thin rim (2-10 micrometer) of charred and coagulated tissue. No damage was observed in the cartilage surrounding the rim. The presence of sharp demarcation between the tissue areas ablated by laser energy and the undamaged areas argues for the potential usefulness of the Er:YAG laser in surgery of cartilages.

Infrared coagulation in the treatment of condyloma acuminata in the female genital tract.

PubMed

Bekassy, Z; Weström, L

1987-01-01

An infrared contact coagulator was used for the treatment of genital condyloma acuminata in 89 women. After direct application to the condyloma, the device produces a precisely adjustable tissue necrosis without tissue adhesion. Of the 89 women, 74 returned for scheduled follow-up visits after one, three, and six months. Treatment failure, i.e., recurrence of warts in a treated area, was seen in 13 (10.8%) of 120 treated areas, or in 13 (17.6%) of 74 patients. No complications were observed. The physical working principle of infrared coagulation as well as the results in treatment of condyloma are the same as those of the CO2 laser, but the equipment is cheaper, safer, and more easily handled. It can be used in out-patient departments of clinical and general practices.

CO2 laser therapy of rhinophyma

NASA Astrophysics Data System (ADS)

Voigt, Peggy; Jovanovic, Sergije; Sedlmaier, Benedikt W.

2000-06-01

Laser treatment of skin changes has become common practice in recent years. High absorption of the CO2 laser wavelength in water is responsible for its low penetration dpt in biological tissue. Shortening the tissue exposure time minimizes thermic side effects of laser radiation such as carbonization and coagulation. This can be achieved with scanner systems that move the focused laser beam over a defined area by microprocessor-controlled rapidly rotating mirrors. This enables controlled and reliable removal of certain dermal lesions, particularly hypertrophic scars, scars after common acne, wrinkles and rhinophyma. Laser ablation of rhinophyma is a stress-minimizing procedure for the surgeon and the patient, since it is nearly bloodless and can be performed under local anaesthesia. Cosmetically favorable reepithelization of the lasered surfaces is achieved within a very short period of time.

Potassium titanyl phosphate laser tissue ablation: development and experimental validation of a new numerical model.

PubMed

Elkhalil, Hossam; Akkin, Taner; Pearce, John; Bischof, John

2012-10-01

The photoselective vaporization of prostate (PVP) green light (532 nm) laser is increasingly being used as an alternative to the transurethral resection of prostate (TURP) for treatment of benign prostatic hyperplasia (BPH) in older patients and those who are poor surgical candidates. In order to achieve the goals of increased tissue removal volume (i.e., "ablation" in the engineering sense) and reduced collateral thermal damage during the PVP green light treatment, a two dimensional computational model for laser tissue ablation based on available parameters in the literature has been developed and compared to experiments. The model is based on the control volume finite difference and the enthalpy method with a mechanistically defined energy necessary to ablate (i.e., physically remove) a volume of tissue (i.e., energy of ablation E(ab)). The model was able to capture the general trends experimentally observed in terms of ablation and coagulation areas, their ratio (therapeutic index (TI)), and the ablation rate (AR) (mm(3)/s). The model and experiment were in good agreement at a smaller working distance (WD) (distance from the tissue in mm) and a larger scanning speed (SS) (laser scan speed in mm/s). However, the model and experiment deviated somewhat with a larger WD and a smaller SS; this is most likely due to optical shielding and heat diffusion in the laser scanning direction, which are neglected in the model. This model is a useful first step in the mechanistic prediction of PVP based BPH laser tissue ablation. Future modeling efforts should focus on optical shielding, heat diffusion in the laser scanning direction (i.e., including 3D effects), convective heat losses at the tissue boundary, and the dynamic optical, thermal, and coagulation properties of BPH tissue.

Modeling of growth, evaporation and sedimentation effects on transmission of visible and IR laser beams in artificial fogs

NASA Technical Reports Server (NTRS)

Yue, G. K.; Deepak, A.

1980-01-01

The dense polydisperse aerosol particles in a quiet chamber may spontaneously go through different microphysical processes including gravitational sedimentation, thermal coagulation, and growth or evaporation. In an earlier paper, we presented the results of a parametric study of the combined and separate effects of thermal coagulation and sedimentation on the time dependence of extinction of four visible and IR laser beams traversing an aerosol medium. As a continuation of this series of studies, the separate and combined effects of growth or evaporation and gravitational sedimentation on the time dependence of extinction of the same four visible and IR laser beams traversing in artificial fogs will be reported in this paper. The method of numerically modeling the change of water droplet size distribution with time due to growth/evaporation and the cutoff of larger aerosols due to gravitational sedimentation is described in detail. Factors governing the relative importance of these two processes are discussed. Results of this study show that the relative humidity or ambient temperature is a crucial parameter in determining the optical depth of the water droplet and aerosol media undergoing microphysical processes.

Photocoagulation in the treatment of bleeding peptic ulcer

NASA Astrophysics Data System (ADS)

Otto, Wlodzimierz; Paczkowski, Pawel M.

1996-03-01

The authors present their experience in the endoscopic laser photocoagulation of bleeding peptic ulcer. From 1991 to June 1995, 203 patients admitted for UGI bleeding from peptic ulcer have been treated by this method. The source of bleeding was confirmed by endoscopy. The patients were divided into two groups: actively bleeding peptic ulcer (group IA and IB according to Forrest's classification) and ulcer with stigmata of recent bleeding (group IIA/IIB). The former group consisted of 106 patients, among whom over 40 percent (45 patients) presented signs of hypovolemic shock on admission. Nd:YAG laser (Surgical Laser Technologies) was used in a continuous mode with a contact (8 - 20 watts) or non-contact (over 50 watts) method of coagulation. In actively bleeding patients photocoagulation resulted in stopping the hemorrhage in 95 (90%). Recurrent bleeding occurred in 16 cases; in 9 of them it was stopped by repeated photocoagulation. In this group 18 patients required surgical intervention. The mortality was of 10.3% (11 patients). In 97 patients with recent bleeding stigmata photocoagulation provoked heavy hemorrhage in 3 (in 2 cases stopped by prolonged coagulation). In 9 of the remaining 94 patients recurrent bleeding occurred. Nine patients required surgical intervention. Mortality in this group was of 6%.

Treatment Outcomes and Adverse Events Following In-Office Angiolytic Laser With or Without Concurrent Polypectomy for Vocal Fold Polyps.

PubMed

Lin, Yu-Hsuan; Wang, Chi-Te; Lin, Feng-Chuan; Liao, Li-Jen; Lo, Wu-Chia; Cheng, Po-Wen

2018-03-01

In-office angiolytic laser procedures have been used successfully as an alternative treatment for vocal fold polyps; little is known in detail about the treatment outcomes and adverse events. To examine the outcomes and incidence rates of adverse events associated with in-office angiolytic laser procedures with or without concurrent polypectomy as an alternative treatment for vocal fold polyps. Retrospective cohort study at a tertiary medical center. We identified 114 consecutive patients with vocal polyps who underwent in-office angiolytic laser treatments between January 1, 2014, and August 31, 2016. After the exclusion of 17 with missing or incomplete data, 97 were enrolled. In-office 532-nm laser procedures with or without concurrent polypectomy. Between 1 and 2 months after the surgical procedures, we collected the following outcome data: videolaryngostroboscopy, perceptual rating of voice quality, acoustic analysis, maximal phonation time, and subjective rating of voice quality using a visual analogue scale and 10-item voice handicap index. This study enrolled 97 patients (mean [SD] age, 45.6 [11.3] years; 48 [49%] male). The mean duration of symptoms was 10.1 months (range, 1-60 months). Twenty-nine patients (30%) had angiolytic laser procedures only, while 68 (70%) received laser with concurrent polypectomy. Both treatment modalities offered significant improvements. Only 1 patient (1%) receiving angiolytic laser with concurrent polypectomy underwent another treatment session, so this group had significantly less need for multiple treatments than those receiving laser treatment alone (6 [21%]; effect size, -1.57; 95% CI, -2.77 to -0.36). We identified 8 adverse events (8% of the cases): vocal fold edema (n = 5), vocal hematoma (n = 2), and vocal ulceration (n = 1). Patients treated with laser plus concurrent polypectomy had significantly fewer adverse events than those treated with angiolytic laser alone (2 [3%] vs 6 [21%]; effect size, 1.20; 95% CI, 0.26 to 2.13). In-office angiolytic laser procedures can be an effective alternative treatment for vocal polyps, although with possible need for multiple treatment sessions and occasional occurrence of minor postoperative adverse events. Concurrent polypectomy following laser coagulation allows less laser energy delivery and reduces the risk of postoperative adverse events and the need for additional treatment sessions.

Ho:YAG laser arthroscopy of the knee

NASA Astrophysics Data System (ADS)

Sisto, Domenick J.; Blazina, Martin E.; Hirsh, Linda C.

1994-09-01

The HO:YAG laser is a near-contact laser with a capacity to ablate or cut tissues. The ablation function allows the surgeon to remove meniscal tissue, lyse and resect adhesions, melt loose bodies, and dissolve inflamed synovium. The cutting function of the laser is utilized to perform a lateral release or resect torn menisci. The laser can also be utilized to drill holes in Grade IV chondromalacic lesions to initiate a healing response. The laser has been embraced by orthopaedic surgeons because of its shape and versatility. The tip is only 2 mm wide and can be delivered into the tight posterior compartments of the knee with no damaging contact with the articular surfaces. The laser coagulates as it works and bleeding is minimized. The laser can function both as a cutting and ablating tool. The laser can also drill holes into subchondral bone to, hopefully, initiate a healing response.

Advanced technology in neurosurgery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pluchino, F.; Broggi, G.

1987-01-01

Technological improvements in neurosurgery are discussed. The use of surgical lasers, ultrasound aspirators, bipolar coagulator and operative microscopes for surgery of deep-seated neoplasms and vascular malformations is discussed. Intraoperative monitoring, chronotherapy, chronic neurostimulation and stereotactic interstitial irradiation are covered and indications for interventional neuroradiology are reviewed.

Curriculum in biomedical optics and laser-tissue interactions

NASA Astrophysics Data System (ADS)

Jacques, Steven L.

2003-10-01

A graduate student level curriculum has been developed for teaching the basic principles of how lasers and light interact with biological tissues and materials. The field of Photomedicine can be divided into two topic areas: (1) where tissue affects photons, used for diagnostic sensing, imaging, and spectroscopy of tissues and biomaterials, and (2) where photons affect tissue, used for surgical and therapeutic cutting, dissecting, machining, processing, coagulating, welding, and oxidizing tissues and biomaterials. The courses teach basic principles of tissue optical properties and light transport in tissues, and interaction of lasers and conventional light sources with tissues via photochemical, photothermal and photomechanical mechanisms.

Interaction of nanosecond ultraviolet laser pulses with reactive dusty plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wetering, F. M. J. H. van de; Oosterbeek, W.; Beckers, J.

2016-05-23

Even though UV laser pulses that irradiate a gas discharge are small compared to the plasma volume (≲3%) and plasma-on time (≲6 × 10{sup −6}%), they are found to dramatically change the discharge characteristics on a global scale. The reactive argon–acetylene plasma allows the growth of nanoparticles with diameters up to 1 μm, which are formed inside the discharge volume due to spontaneous polymerization reactions. It is found that the laser pulses predominantly accelerate and enhance the coagulation phase and are able to suppress the formation of a dust void.

21 CFR 886.1360 - Visual field laser instrument.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Visual field laser instrument. 886.1360 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1360 Visual field laser instrument. (a) Identification. A visual field laser instrument is an AC-powered device intended to provide...

21 CFR 886.1360 - Visual field laser instrument.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Visual field laser instrument. 886.1360 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1360 Visual field laser instrument. (a) Identification. A visual field laser instrument is an AC-powered device intended to provide...

21 CFR 886.1360 - Visual field laser instrument.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Visual field laser instrument. 886.1360 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1360 Visual field laser instrument. (a) Identification. A visual field laser instrument is an AC-powered device intended to provide...

21 CFR 886.1360 - Visual field laser instrument.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Visual field laser instrument. 886.1360 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1360 Visual field laser instrument. (a) Identification. A visual field laser instrument is an AC-powered device intended to provide...

Neurosurgery contact handheld probe based on sapphire shaped crystal

NASA Astrophysics Data System (ADS)

Shikunova, I. A.; Stryukov, D. O.; Rossolenko, S. N.; Kiselev, A. M.; Kurlov, V. N.

2017-01-01

A handheld contact probe based on sapphire shaped crystal is developed for intraoperative spectrally-resolved optical diagnostics, laser coagulation and aspiration of malignant brain tissue. The technology was integrated into the neurosurgical workflow for intraoperative real-time identification and removing of invasive brain cancer.

Operation and performance of the Ciba-Corning 512 coagulation monitor during parabolic flight

NASA Technical Reports Server (NTRS)

Gocke, Robyn; Lloyd, Charles W.; Greenthaner, Nancy K.

1991-01-01

The goal was to assess the functionality and evaluate the procedures and operations required to operate the Ciba-Corning 512 Coagulation Monitor during parabolic flight. This monitor determines the clotting characteristics of blood. The analyzer operates by laser detection of the cessation of blood flow in a capillary channel within a test cartridge. Test simulator results were excellent for both pre-and post-flight. In-flight results were not obtained due to the warm-up time required for the simulator. Since this is an electronic function only, the expected results on the simulator would be the same in zero-g.

Evaluation of the learning curve for thulium laser enucleation of the prostate with the aid of a simulator tool but without tutoring: comparison of two surgeons with different levels of endoscopic experience.

PubMed

Saredi, Giovanni; Pirola, Giacomo Maria; Pacchetti, Andrea; Lovisolo, Jon Alexander; Borroni, Giacomo; Sembenini, Federico; Marconi, Alberto Mario

2015-06-09

The aim of this study was to determine the learning curve for thulium laser enucleation of the prostate (ThuLEP) for two surgeons with different levels of urological endoscopic experience. From June 2012 to August 2013, ThuLEP was performed on 100 patients in our institution. We present the results of a prospective evaluation during which we analyzed data related to the learning curves for two surgeons of different levels of experience. The prostatic adenoma volumes ranged from 30 to 130 mL (average 61.2 mL). Surgeons A and B performed 48 and 52 operations, respectively. Six months after surgery, all patients were evaluated with the International Prostate Symptom Score questionnaire, uroflowmetry, and prostate-specific antigen test. Introduced in 2010, ThuLEP consists of blunt enucleation of the prostatic apex and lobes using the sheath of the resectoscope. This maneuver allows clearer visualization of the enucleation plane and precise identification of the prostatic capsule. These conditions permit total resection of the prostatic adenoma and coagulation of small penetrating vessels, thereby reducing the laser emission time. Most of the complications in this series were encountered during morcellation, which in some cases was performed under poor vision because of venous bleeding due to surgical perforation of the capsule during enucleation. Based on this analysis, we concluded that it is feasible for laser-naive urologists with endoscopic experience to learn to perform ThuLEP without tutoring. Those statements still require further validation in larger multicentric study cohort by several surgeon. The main novelty during the learning process was the use of a simulator that faithfully reproduced all of the surgical steps in prostates of various shapes and volumes.

Therapeutic Applications Of Argon Laser

NASA Astrophysics Data System (ADS)

Brunetaud, J. M.; Mosquet, L.; Mordon, S.; Rotteleur, G.

1984-03-01

Argon laser has a C.W. emission and emits several lines between 487 and 544 nm. This radiation is well absorbed by living tissue and especially where there are red pigments (hemoglobin, myoglobin) or black pigments (melanine). Therapeutic applications mainly use thermal effects. By varying the parameters, (optic power, size of exposed area, exposure time) ; one can obtain a coagulation (maximal tissular temperature 60° - 80°) or a vaporization (temperature over 100°). Section occures when the vaporized area is very thin (below 0.5 mm).

Treatment of condylomata acuminata with CO2 laser under colposcopic control in pregnant women

NASA Astrophysics Data System (ADS)

Wozniak, Jakub; Opala, Tomasz; Pisarska-Krawczyk, Magdalena; Wilczak, Maciej; Pisarski, Tadeusz

1996-03-01

The results of treatment of condylomata acuminata of the anogenital region in pregnant women are presented. All patients were treated between the 28th and 35th weeks of gestation. The laser surgery was done in 23 patients. One laser procedure was done in 14 women. In 5 patients we performed two and in 4 women 3 laser therapies. Complete destruction of pathological changes was obtained and no recurrences were diagnosed. There were no clinical signs of HPV infection in all neonates. In the authors' opinion the use of carbon-dioxide laser under colposcopic control is an efficient and safe method in the treatment of condylomata acuminata in pregnant women. Colposcopic control allows us to discover and coagulate the bleeding spots using the defocused laser beam with low power density.

The regeneration of thermal wound on mice skin (Mus Musculus) after Q-Switch Nd: YAG laser irradiation for cancer therapy candidate

NASA Astrophysics Data System (ADS)

Apsari, R.; Nahdliyatun, E.; Winarni, D.

2017-09-01

The aims of this study are to investigate the regeneration of mice skin tissue (Mus Musculus) irradiated by Q-Switch Nd: YAG laser and morphological change due to Q-Switch Nd: YAG laser irradiation compared to conventional heating (hairdryer). The 2-3 month of twenty-seven mice were used for experimental animals. Mice were incised in the dorsum by the damage effect of laser energy dose (therapeutic dose) of 29.5 J/cm2 with 10 seconds of exposure time, 10 Hz of repetition rate, and 100 pulses of the given single pulse energy. The mice skin tissue was injuried by hairdryer to get burned effect. Mice were divided into three groups, Group I (control) were not treated by anything, Group II were treated by Q-Switch Nd: YAG laser irradiation and sacrificed on (0, 1, 3, 5) days, and Group III were treated by hairdryer then sacrificed on (0, 1, 3, 5) days. Pathology examination showed that the energy of 29,5 J/cm2 dose produced the hole effect (ablation) through the hypodermic layer caused by optical breakdown and collagen coagulation. Thus, the 60 °C temperature of burn showed coagulation necrosis because piknosis discovered in the injured area. The regeneration process showed that the mice skin tissue's ability to regenerate was irradiated by fast laser because of the focus of Q-Switch Nd: YAG laser. It was showed by the scab releases on third day and completely reepithelialization formation on the fifth day. The collagen fibers distribution was same as normal skin tissue on day 5 and so did angiogenesis. Therefore, Q-Switch Nd: YAG laser can be applied for problems of dermatology medical therapies, especially melasma, nevus of ota and tatto therapy. For skin cancer therapy application, energy dose of unregenerated skin tissue is chosen because the death expected effect is permanent.

Cutaneous resurfacing with CO2 and erbium: YAG lasers: preoperative, intraoperative, and postoperative considerations.

PubMed

Alster, T S

1999-02-01

The development and integration of pulsed and scanned CO2 and erbium:YAG laser systems into mainstream surgical practice over the past years has revolutionized cutaneous resurfacing. These lasers are capable of delivering to skin high peak fluences to effect controlled tissue vaporization, while leaving an acceptably narrow zone of residual thermal damage. The inherent technological differences that exist between the two distant laser systems in terms of ablation depths, degree of thermal coagulation, and postoperative side-effects and complications guide patient selection and management. This article reviews the basic principles of CO2 and erbium:YAG laser resurfacing, including preoperative, intraoperative, and postoperative patient considerations. Side-effects and complications encountered after laser resurfacing are discussed with specific guidelines provided on their appropriate management. Anticipated future developments and cutting-edge research endeavors in cutaneous laser resurfacing are also briefly outlined.

Effects of an erbium, chromium: yttrium, scandium, gallium, garnet laser on mucocutanous soft tissues.

PubMed

Rizoiu, I M; Eversole, L R; Kimmel, A I

1996-10-01

Lasers are effective tools for soft tissue surgery. The erbium, chromium: yttrium, scandium, gallium, garnet laser is a new system that incorporates an air-water spray. This study evaluates the cutting margins of this laser and compares healing with laser and conventional scalpel and punch biopsy-induced wounds. New Zealand white rabbits were divided into serial sacrifice groups; the tissues were grossly and microscopically analyzed after laser and convential steel surgical wounding. Wound margins were found to show minimal edge coagulation artifact and were 20 to 40 mm in width. Laser wounds showed minimal to no hemorrhage and re-epithelialization and collagenization were found to occur by day 7 in both laser and conventional groups. The new laser system is an effective soft tissue surgical device; wound healing is comparable to that associated with surgical steel wounds. The minimal edge artifact observed with this laser system should allow for the procurement of diagnostic biopsy specimens.

Laser-produced plasmas in medicine

NASA Astrophysics Data System (ADS)

Gitomer, S. J.; Jones, R. D.

The laser has found numerous applications in medicine, beginning with uses in ophthalmology in the 1960's. Today, lasers are used in tissue cutting, blood coagulation, photo-dynamic cancer therapy, arterial plaque removal, dental drilling, etc. Those areas of laser medicine are examined in which plasmas (ionized gases) are produced. In fact, the presence of a plasma is essential for the application at hand to succeed. Examples are examined for the plasmas produced in ophthalmology (e.g., lens membrane destruction following cataract surgery), in urology and gastroenterology (e.g., kidney and gall stone ablation and fragmentation) and in cardiology and vascular surgery (e.g., laser ablation and removal of fibro-fatty and calcified arterial plaque). Experimental data are presented along with some results from computer simulations of the phenomena. Comments on future directions in these areas are included.

Laser-assisted delivery of topical methotrexate - in vitro investigations.

PubMed

Taudorf, Elisabeth Hjardem

2016-06-01

Ablative fractional lasers (AFXL) are increasingly used to treat dermatological disorders and to facilitate laser-assisted topical drug delivery. In this thesis, laser-tissue interactions generated by stacked pulses with a miniaturized low-power 2,940 nm AFXL were characterized (study I). Knowledge of the correlation between laser parameters and tissue effects was used to deliver methotrexate (MTX) topically through microscopic ablation zones (MAZs) of precise dimensions. MTX is a well-known chemotherapeutic and anti-inflammatory drug that may cause systemic adverse effects, and topical delivery is thus of potential benefit. The impact of MAZ depth (study II) and transport kinetics (study III) on MTX deposition in skin as well as transdermal permeation was determined in vitro. Quantitative analyses of dermal and transdermal MTX concentrations were performed by high performance liquid chromatography (HPLC) (study II & III), while qualitative analyses of MTX biodistribution in skin were illustrated and semi-quantified by fluorescence microscopy (study II & III) and desorption electro spray mass spectrometry imaging (DESI-MSI) (study III). Laser-tissue interactions generated by AFXL: AFXL-exposure generated a variety of MAZ-dimensions. MAZ depth increased linearly with the logarithm of total energy delivered by stacked pulses, but was also affected by variations in power, pulse energy, pulse duration, and pulse repetition rate. Coagulation zones lining MAZs increased linearly with the applied total energy, while MAZ width increased linearly with the logarithm of stacked pulses. Results were gathered in a mathematical model estimating relations between laser parameters and specific MAZ dimensions. Impact of MAZ depth on AFXL-assisted topical MTX delivery: Pretreatment by AFXL facilitated topical MTX delivery to all skin layers. Deeper MAZs increased total MTX deposition in skin compared to superficial MAZs and altered the intradermal biodistribution profile towards maximum accumulation in deeper skin layers. Biodistribution of MTX occurred throughout the skin without being compromised by coagulation zones of varying thickness. The ratio of skin deposition versus transdermal permeation was constant, regardless of MAZ depth. Impact of transport kinetics on AFXL-assisted topical MTX delivery: MTX accumulated rapidly in AFXL-processed skin. MTX was detectable in mid-dermis after 15 min. and saturated the skin after 7 h at a ten-fold increased MTX-concentration compared to intact skin. Transdermal permeation stayed below 1.5% of applied MTX before skin saturation, and increased afterwards up to 8.0% at 24h. MTX distributed radially into the coagulation zone within 15 min of application and could be detected in surrounding skin at 1.5 h. Upon skin saturation, MTX had distributed in an entire mid-dermal skin section. In conclusion, adjusting laser parameters and application time may enable targeted treatments of dermatological disorders and potentially pose a future alternative to systemic MTX in selected dermatological disorders.

Chronic radiation proctopathy: A practical review of endoscopic treatment.

PubMed

Lenz, Luciano; Rohr, Rachel; Nakao, Frank; Libera, Ermelindo; Ferrari, Angelo

2016-02-27

Chronic radiation proctopathy (CRP) is a troublesome complication of pelvic radiotherapy. The most common presentation is rectal bleeding. CRP symptoms interfere with daily activities and decrease quality of life. Rectal bleeding management in patients with CRP represents a conundrum for practitioners. Medical therapy is ineffective in general and surgical approach has a high morbid-mortality. Endoscopy has a role in the diagnosis, staging and treatment of this disease. Currently available endoscopic modalities are formalin, potassium titanyl phosphate laser, neodymium:yttrium-aluminum-garnet laser, argon laser, bipolar electrocoagulation (BiCAP), heater probe, band ligation, cryotherapy, radiofrequency ablation and argon plasma coagulation (APC). Among these options, APC is the most promising.

Monitoring soft tissue coagulation by optical spectroscopy

NASA Astrophysics Data System (ADS)

Lihachev, A.; Lihacova, I.; Heinrichs, H.; Spigulis, J.; Trebst, T.; Wehner, M.

2017-12-01

Laser tissue welding (LTW) or laser tissue soldering (LTS) is investigated since many years for treatment of incisions, wound closure and anastomosis of vessels [1, 2]. Depending on the process, a certain temperature in the range between 65 °C to 85 °C must be reached and held for a few seconds. Care has to be taken not to overheat the tissue, otherwise necrosis or tissue carbonization may occur and will impair wound healing. Usually the temperature is monitored during the process to control the laser power [3]. This requires either bulky equipment or expensive and fragile infrared fibers to feed the temperature signal to an infrared detector. Alternatively, changes in tissue morphology can be directly observed by analysis of spectral reflectance. We investigate spectral changes in the range between 400 nm to 900 nm wavelength. Characteristic spectral changes occur when the temperature of tissue samples increase above 70 °C which is a typical setpoint value for temperature control of coagulation. We conclude that simple spectroscopy in the visible range can provide valuable information during LTS and LTW and probably replace the delicate measurement of temperature. A major advantage is that optical measurements can be performed using standard optical fibers and can be easily integrated into a surgical tool.

Investigation of the efficacy of ultrafast laser in large bowel excision

NASA Astrophysics Data System (ADS)

Mohanan, Syam Mohan P. C.; Beck, Rainer J.; Góra, Wojciech S.; Perry, Sarah L.; Shires, Mike; Jayne, David; Hand, Duncan P.; Shephard, Jonathan D.

2017-02-01

Local resection of early stage tumors in the large bowel via colonoscopy has been a widely accepted surgical modality for colon neoplasm treatment. The conventional electrocautery techniques used for the resection of neoplasia in the mucosal or submucosal layer of colon tissue has been shown to create obvious thermal necrosis to adjacent healthy tissues and lacks accuracy in resection. Ultrafast picosecond (ps) laser ablation using a wavelength of 1030 or 515 nm is a promising surgical tool to overcome the limitations seen with conventional surgical techniques. The purpose of this initial study is to analyze the depth of ablation or the extent of coagulation deployed by the laser as a function of pulse energy and fluence in an ex-vivo porcine model. Precise control of the depth of tissue removal is of paramount importance for bowel surgery where bowel perforation can lead to morbidity or mortality. Thus we investigate the regimes that are optimal for tissue resection and coagulation through plasma mediated ablation of healthy colon tissue. The ablated tissue samples were analyzed by standard histologic methods and a three dimensional optical profilometer technique. We demonstrate that ultrafast laser resection of colonic tissue can minimize the region of collateral thermal damage (<50 μm) with a controlled ablation depth. This surgical modality allows potentially easier removal of early stage lesions and has the capability to provide more control to the surgeon in comparison with a mechanical or electrocautery device.

Finite element model of thermal processes in retinal photocoagulation

NASA Astrophysics Data System (ADS)

Sramek, Christopher; Paulus, Yannis M.; Nomoto, Hiroyuki; Huie, Phil; Palanker, Daniel

2009-02-01

Short duration (< 20 ms) pulses are desirable in patterned scanning laser photocoagulation to confine thermal damage to the photoreceptor layer, decrease overall treatment time and reduce pain. However, short exposures have a smaller therapeutic window (defined as the ratio of rupture threshold power to that of light coagulation). We have constructed a finite-element computational model of retinal photocoagulation to predict spatial damage and improve the therapeutic window. Model parameters were inferred from experimentally measured absorption characteristics of ocular tissues, as well as the thresholds of vaporization, coagulation, and retinal pigment epithelial (RPE) damage. Calculated lesion diameters showed good agreement with histological measurements over a wide range of pulse durations and powers.

New laser treatment approaches for benign prostatic hyperplasia.

PubMed

Fried, Nathaniel M

2007-01-01

The recent introduction of higher power 100 W holmium:yttrium-aluminum-garnet (Ho:YAG) and 80 W potassium titanyl phosphate lasers for rapid incision and vaporization of the prostate has resulted in renewed interest in the use of lasers for treatment of benign prostatic hyperplasia (BPH). Although long-term studies are still lacking, short-term results demonstrate that these procedures are at least as safe and effective in relieving BPH symptoms as transurethral resection of the prostate and may provide reduced morbidity. Other laser techniques, such as interstitial laser coagulation and contact laser vaporization of the prostate, have lost popularity due to complications with increased catheterization time, irritative symptoms, and infection rates. Although Ho:YAG laser enucleation of the prostate is more difficult to learn and a slower procedure than potassium titanyl phosphate laser vaporization, the Ho:YAG laser is currently the most proven laser technique for BPH treatment. This article reviews the latest developments in laser treatment of BPH over the past 2 years and provides a view toward the future of lasers in the treatment of BPH.

Laser-produced plasmas in medicine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gitomer, S.J.; Jones, R.D.

The laser has found numerous applications in medicine, beginning with uses in ophthalmology in the 1960's. Today, lasers are used in tissue cutting, blood coagulation, photodynamic cancer therapy, arterial plaque removal, dental drilling, etc. In this paper the authors examine those areas of laser medicine in which plasmas (ionized gases) are produced. In fact, the presence of a plasma is essential for the application at hand to succeed. We consider examples of the plasmas produced in ophthalmology (e.g., lens membrane destruction following cataract surgery), in urology and gastroenterology (e.g., kidney and gall stone ablation and fragmentation), and in cardiology andmore » vascular surgery (e.g., laser ablation and removal of fibro-fatty and calcified arterial plaque). Experimental data are presented, along with some results from computer simulations of the phenomena. Comments on future directions in these areas are included.« less

Laser-produced plasmas in medicine

NASA Astrophysics Data System (ADS)

Gitomer, Steven J.; Jones, Roger D.

1990-06-01

The laser has found numerous applications in medicine, beginning with uses in ophthalmology in the 1960's. Today, lasers are used in tissue cutting, blood coagulation, photo-dynamic cancer therapy, arterial plaque removal, dental drilling, etc. In this paper, we examine those areas of laser medicine in which plasmas (ionized gases) are produced. In fact, the presence of a plasma is essential for the application at hand to succeed. We consider examples of the plasmas produced in ophthalmology (e.g. lens membrane destruction following cataract surgery), in urology and gastroenterology (e.g. kidney and gall stone ablation and fragmentation) and in cardiology and vascular surgery (e.g. laser ablation and removal of fibro-fatty and calcified arterial plaque). Experimental data are presented along with some results from computer simulations of the phenomena. Comments on future directions in these areas are included.

Bloodcurdling movies and measures of coagulation: Fear Factor crossover trial

PubMed Central

Nemeth, Banne; Scheres, Luuk J J; Lijfering, Willem M

2015-01-01

Objective To assess whether, as has been hypothesised since medieval times, acute fear can curdle blood. Design Crossover trial. Setting Main meeting room of Leiden University’s Department of Clinical Epidemiology, the Netherlands, converted to a makeshift cinema. Participants 24 healthy volunteers aged ≤30 years recruited among students, alumni, and employees of the Leiden University Medical Center: 14 were assigned to watch a frightening (horror) movie followed by a non-threatening (educational) movie and 10 to watch the movies in reverse order. The movies were viewed more than a week apart at the same time of day and both lasted approximately 90 minutes. Main outcome measures The primary outcome measures were markers, or “fear factors” of coagulation activity: blood coagulant factor VIII, D-dimer, thrombin-antithrombin complexes, and prothrombin fragments 1+2. The secondary outcome was participant reported fear experienced during each movie using a visual analogue fear scale. Results All participants completed the study. The horror movie was perceived to be more frightening than the educational movie on a visual analogue fear scale (mean difference 5.4, 95% confidence interval 4.7 to 6.1). The difference in factor VIII levels before and after watching the movies was higher for the horror movie than for the educational movie (mean difference of differences 11.1 IU/dL (111 IU/L), 95% confidence interval 1.2 to 21.0 IU/dL). The effect of either movie on levels of thrombin-antithrombin complexes, D-dimer, and prothrombin fragments 1+2 did not differ. Conclusion Frightening (in this case, horror) movies are associated with an increase of blood coagulant factor VIII without actual thrombin formation in young and healthy adults. Trial registration ClinicalTrials.gov NCT02601053. PMID:26673787

Laser solder welding of articular cartilage: tensile strength and chondrocyte viability.

PubMed

Züger, B J; Ott, B; Mainil-Varlet, P; Schaffner, T; Clémence, J F; Weber, H P; Frenz, M

2001-01-01

The surgical treatment of full-thickness cartilage defects in the knee joint remains a therapeutic challenge. Recently, new techniques for articular cartilage transplantation, such as mosaicplasty, have become available for cartilage repair. The long-term success of these techniques, however, depends not only on the chondrocyte viability but also on a lateral integration of the implant. The goal of this study was to evaluate the feasibility of cartilage welding by using albumin solder that was dye-enhanced to allow coagulation with 808-nm laser diode irradiation. Conventional histology of light microscopy was compared with a viability staining to precisely determine the extent of thermal damage after laser welding. Indocyanine green (ICG) enhanced albumin solder (25% albumin, 0.5% HA, 0.1% ICG) was used for articular cartilage welding. For coagulation, the solder was irradiated through the cartilage implant by 808-nm laser light and the tensile strength of the weld was measured. Viability staining revealed a thermal damage of typically 500 m in depth at an irradiance of approximately 10 W/cm(2) for 8 seconds, whereas conventional histologies showed only half of the extent found by the viability test. Heat-bath investigations revealed a threshold temperature of minimum 54 degrees C for thermal damage of chondrocytes. Efficient cartilage bonding was obtained by using bovine albumin solder as adhesive. Maximum tensile strength of more than 10 N/cm(2) was achieved. Viability tests revealed that the thermal damage is much greater (up to twice) than expected after light microscopic characterization. This study shows the feasibility to strongly laser weld cartilage on cartilage by use of a dye-enhanced albumin solder. Possibilities to reduce the range of damage are suggested. Copyright 2001 Wiley-Liss, Inc.

Flow Visualization and Laser Velocimetry for Wind Tunnels

NASA Technical Reports Server (NTRS)

Hunter, W. W., Jr. (Editor); Foughner, J. T., Jr. (Editor)

1982-01-01

The need for flow visualization and laser velocimetry were discussed. The purpose was threefold: (1) provide a state-of-the-art overview; (2) provide a forum for industry, universities, and government agencies to address problems in developing useful and productive flow visualization and laser velocimetry measurement techniques; and (3) provide discussion of recent developments and applications of flow visualization and laser velocimetry measurement techniques and instrumentation systems for wind tunnels including the 0.3-Meter Transonic Cryogenic Tunnel.

Possibilities of Nd: YAG laser utilization in medicine

NASA Astrophysics Data System (ADS)

Frank, Frank

The thermic effect caused by the shrinkage and the drying of the tissues is used for cutting, denaturation, and coagulation of tissues with simultaneous filling of the blood and lymphatic vessels. The surgical Nd:YAG lasers, whose utilization is based on photothermic effects, have 120 W power and are used in neurosurgery, dermatology, gastroenterology, gynecology, urology, lung sickness, and jaw and vessel surgery. The treatment of tumors is particularly interesting because of the total destruction of the ill tissue, the homogeneity of the necrose and the obturation of the blood and lymphatic vessels. In all cases, the laser is a better solution for the patients and allows a shorter stay in hospital.

Visual servoing for a US-guided therapeutic HIFU system by coagulated lesion tracking: a phantom study.

PubMed

Seo, Joonho; Koizumi, Norihiro; Funamoto, Takakazu; Sugita, Naohiko; Yoshinaka, Kiyoshi; Nomiya, Akira; Homma, Yukio; Matsumoto, Yoichiro; Mitsuishi, Mamoru

2011-06-01

Applying ultrasound (US)-guided high-intensity focused ultrasound (HIFU) therapy for kidney tumours is currently very difficult, due to the unclearly observed tumour area and renal motion induced by human respiration. In this research, we propose new methods by which to track the indistinct tumour area and to compensate the respiratory tumour motion for US-guided HIFU treatment. For tracking indistinct tumour areas, we detect the US speckle change created by HIFU irradiation. In other words, HIFU thermal ablation can coagulate tissue in the tumour area and an intraoperatively created coagulated lesion (CL) is used as a spatial landmark for US visual tracking. Specifically, the condensation algorithm was applied to robust and real-time CL speckle pattern tracking in the sequence of US images. Moreover, biplanar US imaging was used to locate the three-dimensional position of the CL, and a three-actuator system drives the end-effector to compensate for the motion. Finally, we tested the proposed method by using a newly devised phantom model that enables both visual tracking and a thermal response by HIFU irradiation. In the experiment, after generation of the CL in the phantom kidney, the end-effector successfully synchronized with the phantom motion, which was modelled by the captured motion data for the human kidney. The accuracy of the motion compensation was evaluated by the error between the end-effector and the respiratory motion, the RMS error of which was approximately 2 mm. This research shows that a HIFU-induced CL provides a very good landmark for target motion tracking. By using the CL tracking method, target motion compensation can be realized in the US-guided robotic HIFU system. Copyright © 2011 John Wiley & Sons, Ltd.

Ocular dynamics and visual tracking performance after Q-switched laser exposure

NASA Astrophysics Data System (ADS)

Zwick, Harry; Stuck, Bruce E.; Lund, David J.; Nawim, Maqsood

2001-05-01

In previous investigations of q-switched laser retinal exposure in awake task oriented non-human primates (NHPs), the threshold for retinal damage occurred well below that of the threshold for permanent visual function loss. Visual function measures used in these studies involved measures of visual acuity and contrast sensitivity. In the present study, we examine the same relationship for q-switched laser exposure using a visual performance task, where task dependency involves more parafoveal than foveal retina. NHPs were trained on a visual pursuit motor tracking performance task that required maintaining a small HeNe laser spot (0.3 degrees) centered in a slowly moving (0.5deg/sec) annulus. When NHPs reliably produced visual target tracking efficiencies > 80%, single q-switched laser exposures (7 nsec) were made coaxially with the line of sight of the moving target. An infrared camera imaged the pupil during exposure to obtain the pupillary response to the laser flash. Retinal images were obtained with a scanning laser ophthalmoscope 3 days post exposure under ketamine and nembutol anesthesia. Q-switched visible laser exposures at twice the damage threshold produced small (about 50mm) retinal lesions temporal to the fovea; deficits in NHP visual pursuit tracking were transient, demonstrating full recovery to baseline within a single tracking session. Post exposure analysis of the pupillary response demonstrated that the exposure flash entered the pupil, followed by 90 msec refractory period and than a 12 % pupillary contraction within 1.5 sec from the onset of laser exposure. At 6 times the morphological threshold damage level for 532 nm q-switched exposure, longer term losses in NHP pursuit tracking performance were observed. In summary, q-switched laser exposure appears to have a higher threshold for permanent visual performance loss than the corresponding threshold to produce retinal threshold injury. Mechanisms of neural plasticity within the retina and at higher visual brain centers may mediat

Holmium:YAG laser: 12-year study of indications for use and outcomes in benign and malignant otolaryngological conditions.

PubMed

Joseph, J; Jaberoo, M-C; Dilkes, M

2010-08-01

We present the largest recorded case series of holmium:YAG laser use in otolaryngology. This laser's hand-held delivery device is easier to manipulate compared with other ENT lasers, and its pulsed delivery mode gives it enhanced cutting and coagulation properties. We conducted a 12-year, retrospective study of holmium:YAG laser use in a tertiary referral centre. Sixty-eight patients were included. Nineteen received primary laser treatment of squamous cell carcinoma of the upper aerodigestive tract (nine with simultaneous neck dissection), and 49 underwent either palatine or lingual tonsillectomy for benign disease. One cancer patient developed a pharyngo-cutaneous fistula, and a second suffered a secondary haemorrhage. No other complications were recorded. There were no local recurrences. The holmium:YAG laser is safe and effective for benign and malignant otolaryngological conditions. In cancer treatment, it may be best to delay neck dissection until the primary site has healed, in order to avoid fistula formation.

Nd-YAG Laser Treatment for Tracheobronchial Obstruction

PubMed Central

Lee, Yu-Chin; Chiang, Kuo-Hwa

1996-01-01

The Nd-YAG laser has good tissue penetration and coagulation effects thus has become an important weapon for photoresection of tracheobronchial obstructive lesions since 1980. Treatment of benign lesions including benign tumors and scar tissues using the Nd-YAG laser has good results. In the treatment of malignant tumors however, it has a lower effectivity rate when compared to benign lesions. From July 1984 to September 1995, a total of 65 patients were treated with Nd-YAG laser for tracheobronchial obstruction. There were 32 (49%) malignant tumors and 33 (51%) benign lesions. 116 resections were performed in 48 patients using the non-contact Nd-YAG laser (MBB, Medilas 2) before 1992. Thereafter, another 41 resections were performed in 17 cases using contact Nd-YAG laser (SLT, CL-X). The overall effectivity rate was 60%. The effectivity rate for benign lesions was 81.3% and 39.4% for malignant tumor. The effectivity rate between non-contact and contact Nd-YAG laser was not significantly different. PMID:18493424

Nd-YAG Laser Treatment for Tracheobronchial Obstruction.

PubMed

Perng, R P; Lee, Y C; Chiang, K H

1996-01-01

The Nd-YAG laser has good tissue penetration and coagulation effects thus has become an important weapon for photoresection of tracheobronchial obstructive lesions since 1980.Treatment of benign lesions including benign tumors and scar tissues using the Nd-YAG laser has good results. In the treatment of malignant tumors however, it has a lower effectivity rate when compared to benign lesions. From July 1984 to September 1995, a total of 65 patients were treated with Nd-YAG laser for tracheobronchial obstruction. There were 32 (49%) malignant tumors and 33 (51%) benign lesions. 116 resections were performed in 48 patients using the non-contact Nd-YAG laser (MBB, Medilas 2) before 1992. Thereafter, another 41 resections were performed in 17 cases using contact Nd-YAG laser (SLT, CL-X). The overall effectivity rate was 60%. The effectivity rate for benign lesions was 81.3% and 39.4% for malignant tumor. The effectivity rate between non-contact and contact Nd-YAG laser was not significantly different.

Computational model of retinal photocoagulation and rupture

NASA Astrophysics Data System (ADS)

Sramek, Christopher; Paulus, Yannis M.; Nomoto, Hiroyuki; Huie, Phil; Palanker, Daniel

2009-02-01

In patterned scanning laser photocoagulation, shorter duration (< 20 ms) pulses help reduce thermal damage beyond the photoreceptor layer, decrease treatment time and minimize pain. However, safe therapeutic window (defined as the ratio of rupture threshold power to that of light coagulation) decreases for shorter exposures. To quantify the extent of thermal damage in the retina, and maximize the therapeutic window, we developed a computational model of retinal photocoagulation and rupture. Model parameters were adjusted to match measured thresholds of vaporization, coagulation, and retinal pigment epithelial (RPE) damage. Computed lesion width agreed with histological measurements in a wide range of pulse durations and power. Application of ring-shaped beam profile was predicted to double the therapeutic window width for exposures in the range of 1 - 10 ms.

Real-time temperature monitoring with fiber Bragg grating sensor during diffuser-assisted laser-induced interstitial thermotherapy.

PubMed

Pham, Ngot Thi; Lee, Seul Lee; Park, Suhyun; Lee, Yong Wook; Kang, Hyun Wook

2017-04-01

High-sensitivity temperature sensors have been used to validate real-time thermal responses in tissue during photothermal treatment. The objective of the current study was to evaluate the feasible application of a fiber Bragg grating (FBG) sensor for diffuser-assisted laser-induced interstitial thermotherapy (LITT) particularly to treat tubular tissue disease. A 600 - ? m core-diameter diffuser was employed to deliver 980-nm laser light for coagulation treatment. Both a thermocouple and a FBG were comparatively tested to evaluate temperature measurements in ex vivo liver tissue. The degree of tissue denaturation was estimated as a function of irradiation times and quantitatively compared with light distribution as well as temperature development. At the closer distance to a heat source, the thermocouple measured up to 41% higher maximum temperature than the FBG sensor did after 120-s irradiation (i.e., 98.7 ° C ± 6.1 ° C for FBG versus 131.0 ° C ± 5.1 ° C for thermocouple; p < 0.001 ). Ex vivo porcine urethra tests confirmed the real-time temperature measurements of the FBG sensor as well as consistently circumferential tissue denaturation after 72-s irradiation ( coagulation thickness = 2.2 ± 0.3 ?? mm ). The implementation of FBG can be a feasible sensing technique to instantaneously monitor the temperature developments during diffuser-assisted LITT for treatment of tubular tissue structure.

Laser-produced plasmas in medicine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gitomer, S.J.; Jones, R.D.

The laser has found numerous applications in medicine, beginning with uses in ophthalmology in the 1960's. Today, lasers are used in tissue cutting, blood coagulation, photo-dynamic cancer therapy, arterial plaque removal, dental drilling, etc. In this paper, we examine those areas of laser medicine in which plasmas (ionized gases) are produced. In fact, the presence of a plasma is essential for the application at hand to succeed. We consider examples of the plasmas produced in ophthalmology (e.g., lens membrane destruction following cataract surgery), in urology and gastroenterology (e.g., kidney and gall stone ablation and fragmentation) and in cardiology and vascularmore » surgery (e.g., laser ablation and removal of fibro-fatty and calcified arterial plaque). Experimental data are presented along with some results from computer simulations of the phenomena. Comments on future directions in these areas are included. 63 refs.« less

[Indications for Retinal Laser Therapy Revisited].

PubMed

Enders, P; Schaub, F; Fauser, S

2017-02-10

Background Laser therapy is an important treatment option in retinal diseases, especially in cases of vascular involvement. Most approaches are based on coagulation of retinal structures. As there is increasing use of agents targetting vascular endothelial growth factor in the treatment of macular diseases, indications for the use of laser treatment need to be reviewed carefully, especially with respect to their significance in first line therapy. This article explains recent strategies and treatment protocols. Materials and Methods Review of current literature in PubMed as well as synopsis of relevant guidelines. Results and Conclusion Retinal laser therapy is still widely used within retinal opthalmology and covers a large spectrum of indications. Despite the success of medical approaches, retinal laser therapy remains an indispensable treatment option for proliferative diabetic retinopathy, central or peripheral vein occlusion and less frequent pathologies, such as retinopathy of prematurity or Coats's disease. Georg Thieme Verlag KG Stuttgart · New York.

Dermatocosmetologic aspects of treatment of basal-cell skin cancer

NASA Astrophysics Data System (ADS)

Geinitz, A. V.; Stranadko, Ye. F.; Yusupova, Zh. M.; Tkachenko, S. B.

2005-08-01

The obtained clinical findings demonstrate excellent results after surgical MSC treatment with the application of modem laser surgical technologies. All the operated patients were under oncologist"s control during 1.5-2.5 years. In 6 cases we observed topical recurrences which needed a repeated intervention. Thus, our experience of applying LPh for surgical treatment of basal-cell carcinomas of the head and neck dem- onstrate that in the analysed cases it is more reasonable to use two models of laser devices different in their physical parameters. These devices are used at different surgical stages so as to provide a precise effect in laser tumour va- porization within the borders of the healthy tissue, to make better vascular coagulation and laser smoothing of wound surface. Immediate, direct and long-term results of modern surgical lasers" application for treating skin BSC almost in all cases give good and excellent cosmetic effect after such intenventions.

Surgical effects on soft tissue produced by a 405-nm violet diode laser in vivo

NASA Astrophysics Data System (ADS)

Miyazaki, H.; Kato, J.; Kawai, S.; Hatayama, H.; Uchida, K.; Otsuki, M.; Tagami, J.; Yokoo, S.

2011-12-01

This study evaluated the surgical performance of a 405-nm diode laser in vivo, using living rat liver tissue. Tissue was incised by irradiation with the laser at low output power ranging from 1 W (722 W/cm2) to 3 W (2165 W/cm2) on a manual control at a rate of 1 mm/s. As a control, incisions using a stainless scalpel were compared. Immediately after operation, the surface of the incisions was macroscopically observed and histopathologically evaluated by microscopy. Laser-ablated liver tissue was smooth with observable signs of remnant carbonization and easily acquired hemostasis. The thickness of the denatured layer increased in proportion to the output power; the coagulation layer did not thicken accordingly. Bleeding could not be stopped for tissues incised with the stainless scalpel. The 405-nm diode laser thus proved to be effective for ablating soft tissue with high hemostatic ability at low power.

MR-guided laser-induced interstitial thermotherapy of recurrent glioblastoma multiforme: preliminary results in 16 patients.

PubMed

Schwarzmaier, Hans-Joachim; Eickmeyer, Frank; von Tempelhoff, Wernholt; Fiedler, Volkhard Ulrich; Niehoff, Hendrik; Ulrich, Slif Dagobert; Yang, Qin; Ulrich, Frank

2006-08-01

We investigated the survival after laser-induced interstitial thermotherapy in 16 patients suffering from recurrent glioblastoma multiforme. The concept underlying the intervention is the cytoreduction of the tumor tissue by local thermocoagulation. All patients received standard chemotherapy (temozolomide). The median overall survival time after the first relapse was 9.4 months, corresponding to a median overall survival time after laser irradiation of 6.9 months. During the study, however, the median survival after laser coagulation increased to 11.2 months. This survival time is substantially longer than those reported for the natural history (<5 months) or after chemotherapy (temozolomide: 5.4-7.1 months). We conclude that cytoreduction by laser irradiation might be a promising option for patients suffering from recurrent glioblastoma multiforme. In addition, the data indicate the presence of a substantial learning curve. Future work should optimize the therapeutic regimen and evaluate this treatment approach in controlled clinical trials.

Laser-induced thermotherapy: intra- and extralesionary recurrence after incomplete destruction of experimental liver metastasis.

PubMed

Isbert, C; Roggan, A; Ritz, J P; Müller, G; Buhr, H J; Lehmann, K S; Germer, C T

2001-11-01

The aim of this study was to determine the energy (J/mm3 tumor volume) and temperature required for a complete laser-induced thermotherapy (LITT) of experimental liver tumors, and to find out causes and areas of local recurrence followed by incomplete treatment. In VX-2 tumor-bearing rabbits LITT was performed using neodymium:yttrium-aluminum-garnet (Nd:YAG) laser (1064 nm) with a diffuser-tip applicator and a temperature feedback system. The animals were randomized into four groups (n = 20) that differed in the target temperature at the tumor border as follows: 45 degrees C, 50 degrees C, 55 degrees C and 60 degrees C. The target temperature was held for 10 min constant. Histologic examination (hematoxylin and eosin [H and E], nicotinamide adenine dinucleotide phosphate [NADPH]-dehydrogenase) was performed at 0 h, 24 h, 96 h, and 14 days after LITT. The pretreatment tumor volume of 2191 +/- 61 mm3 was the same for all groups (p > 0.05). Energy up to target temperature and total energy required, lesion size, and the rate of incomplete tumor ablation (recurrences) are listed below (ap < 0.05, Kruskal-Wallis test). Histologically, two forms of local recurrences could be differentiated intralesionary and extralesionary. To achieve complete in situ ablation under the given conditions, it is necessary to apply laser energy of 3 J/mm3 tumor volume. A minimum temperature of 60 degrees C on the tumor border presumed an application of 10 min. Recurrence was found outside the coagulation zone (extralesionary) and in high vascularized areas within the coagulation zone (intralesionary).

New application system for laser and ultrasonic therapy in endoscopic surgery

NASA Astrophysics Data System (ADS)

Desinger, Kai; Helfmann, Juergen; Stein, Thomas; Mueller, Gerhard J.

1996-12-01

Flexible acoustic waveguides for selective tissue fragmentation are not yet commercially available. Experimental studies have shown the possibility of transmission of acoustical transients via optical silica glass fibers. The aim of this project is the development of a new endoscopic application system that would enable surgeons to use the laser and the ultrasound technique for therapy simultaneously. The concept of this application system is based on the transmission of laser radiation and ultrasound power via flexible silica glass fibers. Theoretical and experimental results on the feasibility of such an application system for an ultrasonic power delivery system are presented. Piezo-electric transducers are used to provide a high efficiency in generating the ultrasonic power. With reference to the CUSA-technique, a special flexible guiding system has been designed for providing aspiration at the tip and for protection of the fiber. The system transmits via an optical fiber up to 100 Watt Nd:YAG laser radiation. The axial oscillation of the fiber tip is +/- micrometers at a frequency of 27 kHz. First results of in vitro experiments are presented. The parenchymatous cells of liver can be fragmented without destruction of the collagenous matrix. The laser can be optionally used to coagulate bleedings or to cut collagenous tissues in contact. Applications for an acoustical and optical waveguide in ultrasonic surgery are demonstrated. This new approach in developing a first application system for the therapeutical use of laser radiation and power ultrasound in minimal invasive surgery via optical waveguides offers new possibilities in surgery. The laser ultrasonic surgical therapy (LUST) with its thin and flexible applicator provides new working fields especially for neuro or liver surgery. The tip can be bent and thus areas which could not be treated before have now been made accessible. Without changing the instrumentation, the surgeon can use the laser for tissue coagulation or cutting, next to the selective ultrasonic tissue fragmentation, where nerves or vessels will not be affected. Such a LUST-application system could be ready for clinical use in two to four years.

The electrosurgical knife in an optimized intermittent cutting mode for the endoscopic treatment of benign web-like tracheobronchial stenosis.

PubMed

Amat, Beatriz; Esselmann, Albert; Reichle, Guenther; Rohde, Hans-Juergen; Westhoff, Michael; Freitag, Lutz

2012-01-01

The established endoscopic treatment of web-like tracheobronchial stenosis is laser vaporization, but the appearance on the market of a new cutting mode with a lower coagulation effect has been proposed as an alternative to laser due to less injury to the tissue. To study the clinical and functional consequences, as well as the side effects of this technique. Afterwards, we investigated whether the use of an electrosurgical knife with this technique is as effective and convenient as an ND-YAG-laser. Between March 2005 and July 2007, included for study were 22 patients who had undergone 34 interventional bronchoscopy procedures with the VIO-300-D radiofrequency system, using a mode of the Endo-cut I program in conjunction with the reusable knife electrode. All of the patients treated (100%) presented improvements in their symptoms, in the tracheobronchial lumen diameter and in lung function, which were statistically significant. Symptom-free time was 157 ± 93 days. There was an overall decrease observed in mean obstruction (P<.001). Improvements in FVC (P=.01), Raw (P=.0016) and RV/TLC (P=.01) were significantly significant. Less than 50% of the patients needed a second intervention. These patients were compared retrospectively with a similar group of 22 patients treated with Nd-YAG laser. The follow-up analysis showed that only 18% (4/22) of the patients treated with this new technique presented fibrin, compared with 41% (9/22) of those treated with laser therapy (P<.001). The use of this technique is effective for the treatment of benign web-like tracheobronchial stenosis as all the patients showed clinical and functional improvement, and less than 50% required a second intervention. In comparison with laser therapy, an advantage of this technique is that less fibrin is produced, probably due to the reduced anti-coagulation effect. Copyright © 2011 SEPAR. Published by Elsevier Espana. All rights reserved.

Correlation of a scanning laser derived oedema index and visual function following grid laser treatment for diabetic macular oedema.

PubMed

Hudson, C; Flanagan, J G; Turner, G S; Chen, H C; Young, L B; McLeod, D

2003-04-01

To correlate change of an oedema index derived by scanning laser tomography with change of visual function in patients undergoing grid laser photocoagulation for clinically significant diabetic macular oedema (DMO). The sample comprised 24 diabetic patients with retinal thickening within 500 micro m of the fovea. Inclusion criteria included a logMAR visual acuity of 0.25, or better. Patients were assessed twice before a single session of grid laser treatment and within 1 week of, and at 1, 2, 4, and 12 weeks after, treatment. At each visit, patients underwent logMAR visual acuity, conventional and short wavelength automated perimetry (SWAP), and scanning laser tomography. Each visual function parameter was correlated with the mean oedema index. The mean oedema index represented the z-profile signal width divided by the maximum reflectance intensity (arbitrary units). A Pearson correlation coefficient (Bonferroni corrected) was undertaken on the data set of each patient. 13 patients exhibited significant correlation of the mean oedema index and at least one measure of visual function for the 10 degrees x 10 degrees scan field while 10 patients correlated for the 20 degrees x 20 degrees scan field. Seven patients demonstrated correlation for both scan fields. Laser photocoagulation typically resulted in an immediate loss of perimetric sensitivity whereas the oedema index changed over a period of weeks. Localised oedema did not impact upon visual acuity or letter contrast sensitivity when situated extrafoveally. Correlation of change of the oedema index and of visual function following grid laser photocoagulation was not found in all patients. An absence of correlation can be explained by the localised distribution of DMO in this sample of patients, as well as by differences in the time course of change of the oedema index and visual function. The study has objectively documented change in the magnitude and distribution of DMO following grid laser treatment and has established the relation of this change to the change in visual function.

Effect of neodymium:YAG laser capsulotomy on visual function in patients with posterior capsule opacification and good visual acuity.

PubMed

Yotsukura, Erisa; Torii, Hidemasa; Saiki, Megumi; Negishi, Kazuno; Tsubota, Kazuo

2016-03-01

To evaluate the effect of neodymium:YAG (Nd:YAG) laser capsulotomy on the visual function in patients with posterior capsule opacification (PCO) and good visual acuity. Keio University Hospital, Tokyo, Japan. Observational case series. Eyes were evaluated that had previous cataract surgery with a clinical diagnosis of PCO requiring Nd:YAG laser capsulotomy regardless of a good corrected distance visual acuity (CDVA) (at least 20/20). The CDVA, 10% low contrast visual acuity (LCVA), wavefront aberrations from the 3rd to 6th order, and retinal straylight were measured before and after Nd:YAG laser capsulotomy. The study included 16 eyes of 16 patients (10 men, 6 women; mean age 69.5 years ± 9.3 [SD]). The mean CDVA, LCVA, and straylight after Nd:YAG laser capsulotomy improved significantly (P < .05). The root mean square (RMS) of the 3rd Zernike coefficients (S3) and the RMS of the total higher-order aberrations (HOAs) from the 3rd to 6th order decreased significantly after capsulotomy (P < .05). The straylight correlated significantly with the total HOAs (r = 0.727, P = .002) and S3 (r = 0.748, P = .001) before capsulotomy. Subjective symptoms resolved after capsulotomy in all cases. Neodymium:YAG laser capsulotomy enabled a significant improvement in visual function even in patients with PCO with good visual acuity. Straylight measurements might be useful to determine the indications for Nd:YAG laser capsulotomy when patients report visual disturbances without decreased visual acuity. Copyright © 2016 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

21 CFR 886.1360 - Visual field laser instrument.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Visual field laser instrument. 886.1360 Section 886.1360 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1360 Visual field laser instrument...

The impact of pH on floc structure characteristic of polyferric chloride in a low DOC and high alkalinity surface water treatment.

PubMed

Cao, Baichuan; Gao, Baoyu; Liu, Xin; Wang, Mengmeng; Yang, Zhonglian; Yue, Qinyan

2011-11-15

The adjustment of pH is an important way to enhance removal efficiency in coagulation units, and in this process, the floc size, strength and structure can be changed, influencing the subsequent solid/liquid separation effect. In this study, an inorganic polymer coagulant, polyferric chloride (PFC) was used in a low dissolved organic carbon (DOC) and high alkalinity surface water treatment. The influence of coagulation pH on removal efficiency, floc growth, strength, re-growth capability and fractal dimension was examined. The optimum dosage was predetermined as 0.150 mmol/L, and excellent particle and organic matter removal appeared in the pH range of 5.50-5.75. The structure characteristics of flocs formed under four pH conditions were investigated through the analysis of floc size, effect of shear and particle scattering properties by a laser scattering instrument. The results indicated that flocs formed at neutral pH condition gave the largest floc size and the highest growth rate. During the coagulation period, the fractal dimension of floc aggregates increased in the first minutes and then decreased and larger flocs generally had smaller fractal dimensions. The floc strength, which was assessed by the relationship of floc diameter and velocity gradient, decreased with the increase of coagulation pH. Flocs formed at pH 4.00 had better recovery capability when exposed to lower shear forces, while flocs formed at neutral and alkaline conditions had better performance under higher shear forces. Copyright © 2011 Elsevier Ltd. All rights reserved.

Atomic force microscopy visualization of injuries in Enterococcus faecalis surface caused by Er,Cr:YSGG and diode lasers

PubMed Central

López-Jiménez, Lidia; Viñas, Miguel; Vinuesa, Teresa

2015-01-01

Aim: To visualize by Atomic Force Microscopy the alterations induced on Enterococcus. faecalis surface after treatment with 2 types of laser: Erbium chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser and Diode laser. Material and Methods: Bacterial suspensions from overnight cultures of E. faecalis were irradiated during 30 seconds with the laser-lights at 1 W and 2 W of power, leaving one untreated sample as control. Surface alterations on treated E. faecalis were visualized by Atomic Force Microscopy (AFM) and its surface roughness determined. Results: AFM imaging showed that at high potency of laser both cell morphology and surface roughness resulted altered, and that several cell lysis signs were easily visualized. Surface roughness clearly increase after the treatment with Er,Cr:YSGG at 2W of power, while the other treatments gave similar values of surface roughness. The effect of lasers on bacterial surfaces visualized by AFM revealed drastic alterations. Conclusions: AFM is a good tool to evaluate surface injuries after laser treatment; and could constitute a measure of antimicrobial effect that can complete data obtained by determination of microbial viability. Key words:Atomic force microscopy, Er,Cr:YSGG laser, diode laser, Enterococcus faecalis, surface roughness. PMID:25475770

Endoscopic treatment of chronic radiation proctopathy.

PubMed

Wilson, Sydney A; Rex, Douglas K

2006-09-01

Chronic radiation proctopathy is a complication of pelvic radiation therapy. The acute phase of radiation injury to the rectum occurs during or up to 3 months following radiation. Acute radiation injury can continue into a chronic phase or chronic radiation proctopathy may develop after a latent period of several months or years. Symptoms associated with the condition include diarrhea, rectal pain, bleeding, tenesmus, and stricture formation. Of the various symptoms, only bleeding from radiation-induced telangiectasias is amenable to endoscopic therapy. This paper summarizes the findings of experts in the field on endoscopic treatment of bleeding from chronic radiation proctopathy. Medical management is generally ineffective in controlling bleeding from chronic radiation proctopathy. Surgical intervention has a high incidence of morbidity. Promising advances have been made in endoscopic therapy, including formalin, neodymium/yttrium aluminum garnet, argon and potassium titanyl phosphate laser treatments, as well as argon plasma coagulation. Argon plasma coagulation presents an effective, efficient, inexpensive and reasonably safe noncontact method for destruction of radiation telangiectasias. Based on currently available data and trends, argon plasma coagulation is the favored treatment for bleeding from chronic radiation proctopathy.

[Favourable outcome after fetoscopic laser surgery for twin-twin transfusion syndrome: experience of an emerging centre].

PubMed

Delabaere, A; Accoceberry, M; Niro, J; Velemir, L; Laurichesse-Delmas, H; Coste, K; Bœuf, B; Labbe, A; Storme, B; Lemery, D; Gallot, D

2011-09-01

Our objective was to report perinatal outcome during the first three years of an emerging centre for laser photocoagulation in twin-twin transfusion syndrome (TTTS) and to compare with outcome observed earlier in the same centre when management consisted in recurrent amniodrainage. We conducted a single centre retrospective study. We compared perinatal outcome of 19 consecutive cases of mid trimester TTTS managed by amniodrainage over a 10-year period with 49 cases of TTTS managed by laser photocoagulation over a 3-year period. Laser photocoagulation increased survival rate at birth (P=0.02) and at postnatal day 28 (P=0.01). Neurologic and cardiologic complications did not differ significantly (P=0.5 and P=0.3 respectively). We observed a significant increase in survival of the donor after laser coagulation at birth (P=0.04). Our study demonstrated better outcome after laser photocoagulation. Early results of an emerging centre appeared comparable to those of more experienced centres. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

Neurosurgical sapphire handheld probe for intraoperative optical diagnostics, laser coagulation and aspiration of malignant brain tissue

NASA Astrophysics Data System (ADS)

Shikunova, Irina A.; Zaytsev, Kirill I.; Stryukov, Dmitrii O.; Dubyanskaya, Evgenia N.; Kurlov, Vladimir N.

2017-07-01

In this paper, a handheld contact probe based on sapphire shaped crystal was developed for the intraoperative optical diagnosis and aspiration of malignant brain tissue combined with the laser hemostasis. Such a favorable combination of several functions in a single instrument significantly increases its clinical relevance. It makes possible highly-accurate real-time detection and removal of either large-scale malignancies or even separate invasive cancer cells. The proposed neuroprobe was integrated into the clinical neurosurgical workflow for the intraoperative fluorescence identification and removal of malignant tissues of the brain.

The effect of pre-operative topical anaesthetic cream on the ablative width and coagulative depth of ablative fractional resurfacing laser.

PubMed

Punyaratabandhu, Preawphan; Wanitphakdeedecha, Rungsima; Pattanaprichakul, Penvadee; Sitthinamsuwan, Panitta; Phothong, Weeranut; Eimpunth, Sasima; Lohsiriwat, Visnu; Manuskiatti, Woraphong

2017-02-01

Topical anaesthetic cream (TAC) is commonly used as a pre-treatment of ablative fractional resurfacing (AFR) laser. Most of anaesthetic cream contains distilled water as major component. Therefore, pre-operative TAC may interfere the photothermal reaction in the skin treated with fractional carbon-dioxide (FCO 2 ) laser and fractional erbium-doped yttrium aluminium garnet (FEr:YAG) laser. The objective of the study was to compare the ablative width (AW) and coagulative depth (CD) of AFR laser with and without pre-treatment with TAC. Four Thai females who underwent abdominoplasty were included in the study. The excised skin of each subject was divided into four areas. TAC (eutectic mixture of local anaesthesia; EMLA) with 1-h occlusion was applied only on the first and second areas. The first and third areas were treated with FCO 2 at 15 mj and 5% density. The second and fourth areas were treated with FEr:YAG at 28 J/cm 2 and 5% density. Six biopsied specimens were obtained from each area. A total of 96 specimens (24 specimens from each area) were collected from four patients and examined randomly by two dermatopathologists. The ablative width and coagulative depth from each specimen were determined. In FCO 2 -treated specimens, the mean AW of the specimens that were pre-treated with TAC and control was 174.86 ± 24.57 and 188.52 ± 41.32 μm. The mean CD of the specimens that were pre-treated with TAC and control was 594.96 ± 111.72 and 520.03 ± 147.40 μm. There were no significant differences in AW and CD between both groups (p = 0.53 and p = 0.15). In FEr:YAG-treated specimens, the mean AW of the specimens that were pre-treated with TAC and control was 381.11 ± 48.02 and 423.65 ± 60.16 μm. The mean CD of the specimens that were pre-treated with TAC and control was 86.03 ± 29.44 and 71.59 ± 18.99 μm. There were no significant differences in AW and CD between both groups (p = 0.16 and p = 0.24). The pre-treatment with TAC provided no statistically difference from the control group on AW and CD of both FCO 2 and FEr:YAG laser irradiation. However, there was a tendency to have narrower AW and deeper CD of the areas that were pre-treated with TAC when comparing to that of the control.

Four-dimensional optoacoustic temperature mapping in laser-induced thermotherapy

NASA Astrophysics Data System (ADS)

Oyaga Landa, Francisco Javier; Deán-Ben, Xosé Luís.; Sroka, Ronald; Razansky, Daniel

2018-02-01

Photoablative laser therapy is in common use for selective destruction of malignant masses, vascular and brain abnormalities. Tissue ablation and coagulation are irreversible processes occurring shortly after crossing a certain thermal exposure threshold. As a result, accurate mapping of the temperature field is essential for optimizing the outcome of these clinical interventions. Here we demonstrate four-dimensional optoacoustic temperature mapping of the entire photoablated region. Accuracy of the method is investigated in tissue-mimicking phantom experiments. Deviations of the volumetric optoacoustic temperature readings provided at 40ms intervals remained below 10% for temperature elevations above 3°C, as validated by simultaneous thermocouple measurements. The excellent spatio-temporal resolution of the new temperature monitoring approach aims at improving safety and efficacy of laser-based photothermal procedures.

Use of thermo‐coagulation as an alternative treatment modality in a ‘screen‐and‐treat’ programme of cervical screening in rural Malawi

PubMed Central

Kafwafwa, Savel; Brown, Hilary; Walker, Graeme; Madetsa, Belito; Deeny, Miriam; Kabota, Beatrice; Morton, David; Ter Haar, Reynier; Grant, Liz; Cubie, Heather A.

2016-01-01

The incidence of cervical cancer in Malawi is the highest in the world and projected to increase in the absence of interventions. Although government policy supports screening using visual inspection with acetic acid (VIA), screening provision is limited due to lack of infrastructure, trained personnel, and the cost and availability of gas for cryotherapy. Recently, thermo‐coagulation has been acknowledged as a safe and acceptable procedure suitable for low‐resource settings. We introduced thermo‐coagulation for treatment of VIA‐positive lesions as an alternative to cryotherapy within a cervical screening service based on VIA, coupled with appropriate, sustainable pathways of care for women with high‐grade lesions and cancers. Detailed planning was undertaken for VIA clinics, and approvals were obtained from the Ministry of Health, Regional and Village Chiefs. Educational resources were developed. Thermo‐coagulators were introduced into hospital and health centre settings, with theoretical and practical training in safe use and maintenance of equipment. A total of 7,088 previously unscreened women attended VIA clinics between October 2013 and March 2015. Screening clinics were held daily in the hospital and weekly in the health centres. Overall, VIA positivity was 6.1%. Almost 90% received same day treatment in the hospital setting, and 3‐ to 6‐month cure rates of more than 90% are observed. Thermo‐coagulation proved feasible and acceptable in this setting. Effective implementation requires comprehensive training and provider support, ongoing competency assessment, quality assurance and improvement audit. Thermo‐coagulation offers an effective alternative to cryotherapy and encouraged VIA screening of many more women. PMID:27006131

Use of thermo-coagulation as an alternative treatment modality in a 'screen-and-treat' programme of cervical screening in rural Malawi.

PubMed

Campbell, Christine; Kafwafwa, Savel; Brown, Hilary; Walker, Graeme; Madetsa, Belito; Deeny, Miriam; Kabota, Beatrice; Morton, David; Ter Haar, Reynier; Grant, Liz; Cubie, Heather A

2016-08-15

The incidence of cervical cancer in Malawi is the highest in the world and projected to increase in the absence of interventions. Although government policy supports screening using visual inspection with acetic acid (VIA), screening provision is limited due to lack of infrastructure, trained personnel, and the cost and availability of gas for cryotherapy. Recently, thermo-coagulation has been acknowledged as a safe and acceptable procedure suitable for low-resource settings. We introduced thermo-coagulation for treatment of VIA-positive lesions as an alternative to cryotherapy within a cervical screening service based on VIA, coupled with appropriate, sustainable pathways of care for women with high-grade lesions and cancers. Detailed planning was undertaken for VIA clinics, and approvals were obtained from the Ministry of Health, Regional and Village Chiefs. Educational resources were developed. Thermo-coagulators were introduced into hospital and health centre settings, with theoretical and practical training in safe use and maintenance of equipment. A total of 7,088 previously unscreened women attended VIA clinics between October 2013 and March 2015. Screening clinics were held daily in the hospital and weekly in the health centres. Overall, VIA positivity was 6.1%. Almost 90% received same day treatment in the hospital setting, and 3- to 6-month cure rates of more than 90% are observed. Thermo-coagulation proved feasible and acceptable in this setting. Effective implementation requires comprehensive training and provider support, ongoing competency assessment, quality assurance and improvement audit. Thermo-coagulation offers an effective alternative to cryotherapy and encouraged VIA screening of many more women. © 2016 The Authors International Journal of Cancer published by John Wiley & Sons Ltd on behalf of UICC.

The first report on coagulation and phospholipase A2 activities of Persian Gulf lionfish, Pterois russelli, an Iranian venomous fish.

PubMed

Memar, Bahareh; Jamili, Shahla; Shahbazzadeh, Delavar; Bagheri, Kamran Pooshang

2016-04-01

Pterois russelli is a venomous fish belonging to scorpionidae family. Regarding to high significance value for tracing potential therapeutic molecules and special agents from venomous marine creatures, the present study was aimed to characterization of the Persian Gulf lionfish venom. Proteolytic, phospholipase, hemolytic, coagulation, edematogenic and dermonecrotic activities were determined for extracted venom. The LD50 of P. russelli venom was determined by intravenous injection in white Balb/c mice. Phospholipase A2 activity was recorded at 20 μg of total venom. Coagulation activity on human plasma was shown by Prothrombin Time (PT) and activated Partial Thromboplastin Time (APTT) assays and coagulation visualized after 7 and 14 s respectively for 60 μg of crude venom. LD50 was calculated as 10.5 mg/kg. SDS-PAGE revealed the presence of major and minor protein bands between 6 and 205 kDa. Different amounts of crude venom ranged from 1.87 to 30 μg showed proteolytic activity on casein. The highest edematic activity was detected at 20 μg. Our findings showed that the edematic activity was dose dependent and persisted for 48 h after injection. The crude venom did not induce dermonecrotic activity on rabbit skin and showed no hemolytic activity on human, mouse and rabbit erythrocytes. This is the first report for phospholipase A2 and coagulation activity in venomous fish and venomous marine animals respectively. Proteolytic activity of P. russelli venom is in accordance with the other genara of scorpionidae family. According to venom activity on intrinsic and extrinsic coagulation pathways, lionfish venom would be contained an interesting pharmaceutical agent. This study is pending to further characterization of phospholipase A2, coagulation, and protease activities and also in vivo activity on animal model of surface and internal bleeding. Copyright © 2016 Elsevier Ltd. All rights reserved.

Application of erbium: YAG laser in ocular ablation.

PubMed

Tsubota, K

1990-01-01

Recent developments in lasers have provided us the possibility of laser ocular surgery. The xenon, argon, neodymium:YAG and dye lasers have been successfully used in out-patient clinics. The excimer laser has been attracting researchers' interest in the new application of laser to cornea and lens. The erbium:YAG laser emits a 2.94-microns beam that can ablate the transparent ocular tissues such as lenses and corneas. The author has applied this laser to the cornea, lens, vitreous and other ocular tissues. The erbium:YAG laser beam was directed through a 1.5-meter-long, 200-microns-diameter fiberoptic guide. The radiant energy measured about 50 mJ at the end of the probe. The laser was emitted as a 400-microsecond pulse. Freshly enucleated rabbit eyes were used in this study. Laser burns were applied to the tissue surface at various energy settings. At minimal power, the tissues were coagulated by the erbium:YAG laser application. At a power of more than 636-954 mJ/mm2, tissue began to evaporate; the tissue loss was observed under a surgical light microscope. Corneal photoablation, lens ablation, iridotomy, trabeculotomy, cutting of the vitreous and retinal ablation were easily performed. Like the excimer laser, the erbium:YAG laser is a potential tool for ocular surgery.

Update on the use of diode laser in the management of benign prostate obstruction in 2014.

PubMed

Lusuardi, Lukas; Mitterberger, Michael; Hruby, Stephan; Kunit, Thomas; Kloss, Birgit; Engelhardt, Paul F; Sieberer, Manuela; Janetschek, Günter

2015-04-01

To determine the status quo in respect of various diode lasers and present the techniques in use, their results and complications. We assess how these compare with transurethral resection of the prostate and other types of laser in randomized controlled trials (RCTs). When adequate RCTs were not available, case studies and reports were evaluated. Laser for the treatment of benign prostatic hyperplasia (BPH) has aroused the interest and curiosity of urologists as well as patients. The patient associates the term laser with a successful and modern procedure. The journey that started with coagulative necrosis of prostatic adenoma based on neodymium: yttrium-aluminum-garnet (Nd:YAG) laser has culminated in endoscopic "enucleation" with holmium laser. Diode laser is being used in urology for about 10 years now. Various techniques have been employed to relieve bladder outlet obstruction due to BPH. The diode laser scenario is marked by a diversity of surgical techniques and wavelengths. We summarize the current published literature in respect of functional results and complications. More randomized controlled studies are needed to determine the position and the ideal technique of diode laser treatment for BPH.

JPRS Report, Science & Technology, USSR: Life Sciences.

DTIC Science & Technology

1987-06-29

tested included kohlrabi, cauliflower , Brussels sprouts, and red and white cabbages. Results indicated that Savoy cabbage retained the highest water...variations in radioactive substance retention were noted. The highest levels were found in cauliflower , along with Vienna Early Savoy cabbage...conchae, larynx and the external ear . Coagulation by the Nd:YAG laser was attained with fiber optics with infiltrating anesthesia in the case of

Myocardial temperature distribution under cw Nd:YAG laser irradiation in in vitro and in vivo situations: theory and experiment

NASA Astrophysics Data System (ADS)

Splinter, Robert; Littmann, Laszlo; Tuntelder, Jan R.; Svenson, Robert H.; Chuang, Chi Hui; Tatsis, George P.; Semenov, Serguei Y.; Nanney, Glenn A.

1995-01-01

Tissue samples ranging from 2 to 16 mm in thickness were irradiated at 1064 nm with energies ranging from 40 to 2400 J. Coagulation lesions of in vitro and in vivo experiments were subjected to temperature profiling and submitted for histology. Irreversible damage was calculated with the damage integral formalism, following the bioheat equation solved with Monte Carlo computer light-distribution simula-tions. Numerical temperature rise and coagulation depth compared well with the in vitro results. The in vivo data required a change in the optical properties based on integrating sphere measurements for high irradiance to make the experimental and numerical data converge. The computer model has successfully solved several light-tissue interaction situations in which scattering dominates over absorption.

Laser Optometric Assessment Of Visual Display Viewability

NASA Astrophysics Data System (ADS)

Murch, Gerald M.

1983-08-01

Through the technique of laser optometry, measurements of a display user's visual accommodation and binocular convergence were used to assess the visual impact of display color, technology, contrast, and work time. The studies reported here indicate the potential of visual-function measurements as an objective means of improving the design of visual displays.

Effects of malicious ocular laser exposure in commercial airline pilots.

PubMed

Palakkamanil, Mathew M; Fielden, Michael P

2015-12-01

Intentional malicious laser strikes on commercial pilots are committed by individuals who target a laser into airplane cockpits during takeoff and landing. Because laser exposure to pilots is a relatively new but growing occurrence, our study investigates the ocular effect of this laser exposure in pilots. Retrospective chart review by a single ophthalmologist. All commercial airline pilots (58 male, 3 female) who experienced a laser strike while flying between April 2012 and November 2014 who presented to our clinic were included. A retrospective chart review was performed in a retinal specialist's practice. Ocular assessment was performed within 3 days of laser exposure. A complete ophthalmic evaluation was conducted, including Early Treatment Diabetic Retinopathy Study visual acuity, colour vision, visual fields, intraocular pressure, slit-lamp examination, dilated fundus examination, colour fundus photographs, and ocular coherence tomography. Sixty-four laser strike incidents involving commercial pilots were included. All pilots in the study experienced some degree of immediate ocular irritation or light sensitivity. No definite cases of ocular damage were attributed to laser strikes. No pilot had any functional ocular deficits. Our study revealed that laser strikes on aircraft did not result in permanent visual functional or structural deficits. However, laser strikes cause immediate visual effects, including glare, flash blindness, and ocular irritation that can interfere with a pilot's visual function. Given the widespread accessibility of high-power lasers and the rapid increase in incidents, laser strikes threaten to jeopardize aviation safety unless effective preventative measures are put in place. Copyright © 2015 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.

Wavefront-optimized laser in situ keratomileusis with the Allegretto Wave Eye-Q excimer laser and the FEMTO LDV Crystal Line femtosecond laser: 6 month visual and refractive results.

PubMed

Ziaei, Mohammed; Mearza, Ali A; Allamby, David

2015-08-01

To present the first reported series of patients undergoing myopic LASIK with the FEMTO LDV Crystal Line femtosecond laser and the WaveLight Allegretto Eye-Q excimer laser. We report the uncorrected and corrected distance visual acuity (UDVA and CDVA), refractive predictability, efficacy and safety of laser in situ keratomileusis (LASIK) performed with the above laser platforms. This prospective interventional case series study evaluated consecutive eyes with low to moderate myopic astigmatism that underwent LASIK with the FEMTO LDV Crystal Line femtosecond laser and the WaveLight Allegretto Eye-Q 400 Hz excimer laser. Visual and refractive changes as well as complications were evaluated after wavefront-optimized laser treatment. Four hundred and forty four patients (887 eyes) reached the 6-month time gate. Mean age at time of procedure was 31 years (range: 20-59). Mean pre-op spherical-equivalent (SE) was -3.44 diopters (D)±1.34D (range: -0.50 to -7.00) whilst the postoperative spherical equivalent decreased to -0.08±0.31D (range -2.25 to 1.00). At 6-month follow up, 96.9% of patients had monocular uncorrected distance visual acuity of 20/20 or better with 95.2% of patients within ±0.5D of intended refractive outcome. All patients achieved 20/20 binocular distance uncorrected visual acuity. No significant intra-operative or postoperative complications were encountered during the 6-month follow-up period. The combination of the above laser platforms provides safe, effective and predictable results in correcting compound myopic astigmatism with excellent visual outcomes. Copyright © 2015 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

The forward masking effects of low-level laser glare on target location performance in a visual search task

NASA Astrophysics Data System (ADS)

Reddix, M. D.; Dandrea, J. A.; Collyer, P. D.

1992-01-01

The present study examined the effects of low-intensity laser glue, far below a level that would cause ocular damage or flashblindness, on the visually guided performance of aviators. With a forward-masking paradigm, this study showed that the time at which laser glare is experienced, relative to initial acquisition of visual information, differentially affects the speed and accuracy of target-location performance. Brief exposure (300 ms) to laser glare, terminating with a visual scene's onset, produced significant decrements in target-location performance relative to a no-glare control whereas a 150 and 300-ms delay of display onset (DDO) had very little effect. The intensity of the light entering the eye and producing these effects was far below the Maximum Permissible Exposure (MPE) limit for safe viewing of coherent light produced by an argon laser. In addition, these effects were modulated by the distance of the target from the center of the visual display. This study demonstrated that the presence of laser glare is not sufficient, in and of itself, to diminish target-location performance. The time at which laser glare is experienced is an important factor in determining the probability and extent of visually mediated performance decrements.

Possibilities of lasers within NOTES.

PubMed

Stepp, Herbert; Sroka, Ronald

2010-10-01

Lasers possess unique properties that render them versatile light sources particularly for NOTES. Depending on the laser light sources used, diagnostic as well as therapeutic purposes can be achieved. The diagnostic potential offered by innovative concepts such as new types of ultra-thin endoscopes and optical probes supports the physician with optical information of ultra-high resolution, tissue discrimination and manifold types of fluorescence detection. In addition, the potential 3-D capability promises enhanced recognition of tissue type and pathological status. These diagnostic techniques might enable or at least contribute to accurate and safe procedures within the spatial restrictions inherent with NOTES. The therapeutic potential ranges from induction of phototoxic effects over tissue welding, coagulation and tissue cutting to stone fragmentation. As proven in many therapeutic laser endoscopic treatment concepts, laser surgery is potentially bloodless and transmits the energy without mechanical forces. Specialized NOTES endoscopes will likely incorporate suitable probes for improving diagnostic procedures, laser fibres with advantageous light delivery possibility or innovative laser beam manipulation systems. NOTES training centres may support the propagation of the complex handling and the safety aspects for clinical use to the benefit of the patient.

Diffraction-limited 577 nm true-yellow laser by frequency doubling of a tapered diode laser

NASA Astrophysics Data System (ADS)

Christensen, Mathias; Vilera, Mariafernanda; Noordegraaf, Danny; Hansen, Anders K.; Buß, Thomas; Jensen, Ole B.; Skovgaard, Peter M. W.

2018-02-01

A wide range of laser medical treatments are based on coagulation of blood by absorption of the laser radiation. It has, therefore, always been a goal of these treatments to maximize the ratio of absorption in the blood to that in the surrounding tissue. For this purpose lasers at 577 nm are ideal since this wavelength is at the peak of the absorption in oxygenated hemoglobin. Furthermore, 577 nm has a lower absorption in melanin when compared to green wavelengths (515 - 532 nm), giving it an advantage when treating at greater penetration depth. Here we present a laser system based on frequency doubling of an 1154 nm Distributed Bragg Reflector (DBR) tapered diode laser, emitting 1.1 W of single frequency and diffraction limited yellow light at 577 nm, corresponding to a conversion efficiency of 30.5%. The frequency doubling is performed in a single pass configuration using a cascade of two bulk non-linear crystals. The system is power stabilized over 10 hours with a standard deviation of 0.13% and the relative intensity noise is measured to be 0.064 % rms.

Clinical application of CO2 laser in periodontal treatment

NASA Astrophysics Data System (ADS)

Hayase, Yasuhiro

1994-09-01

CO2 lasers in particular are expected to have many dental applications because the CO2 laser beam exhibits strong tissue transpirative actions, such as instant coagulation, carbonization, and vaporization, and because its wavelength at 10.6 micrometers is fully absorbed by water so that the ability to make precise incisions with a high degree of safety is excellent, without damaging the deep tissues. However, clinical application of the CO2 laser has been slowed since a fiber which can conduct the laser beam to the oral cavity has only recently developed. This new fiber is an extremely flexible fiber with a minimum bending radius of 20 mm and utilizes pulse wave modes that have improved the handling characteristics in the mouth, and this has enabled us to apply the CO2 laser to a variety of periodontal conditions. The aim of this study was to evaluate the effectiveness of CO2 lasers for the early treatment of inflammation and pain relief of acute periodontitis, curettage of periodontal pockets, healing after excision of gingiva, and early improvement of gingivitis.

In vitro assessment of fiber sweeping speed during Q-switched 532-nm laser tissue ablation

NASA Astrophysics Data System (ADS)

Rajabhandharaks, Danop; Kang, Hyun Wook; Ko, Woo Jin; Stinson, Douglas; Choi, Benjamin

2011-03-01

Photoselective vaporization of the prostate (PVP) is considered a minimally invasive procedure to treat benign prostatic hyperplasia (BPH). During the PVP, the prostate gland is irradiated by the 532-nm laser and the fiber is swept and dragged along the urethra. In this study the speed of sweeping fiber during the PVP is being investigated. In vitro porcine kidney model was used (N=100) throughout the experiment. A Q-switched 532-nm laser, equipped with sidefiring 750-Um fiber, was employed and set to power levels of 120 and 180 W. The speed of fiber sweeping was the only variable in this study and varied at 0 (i.e. no sweeping), 0.5, 1.0, 1.5, and 2.0 sweep/s. Ablation rate, depth, and coagulation thickness were quantified. Based on the current settings, ablation rate decreased as sweeping speed increased and was maximized between 0 to 1.0 sweep/s for 120-W power level and between 0 to 0.5 sweep/s for 180-W power level. Ablation rate at 180 W was higher than that at 120 W, regardless of sweeping speed. Ablation depth at both 120 and 180 W was maximized at 0 sweep/s and decreased 35% at 0.5 sweep/s. The overall coagulation thickness was less than 1.5 mm and comparable from 0 to 1.5 sweep/s (0.8~0.9 mm) and increased at 2.0 sweep/s (~1.1 mm). This study demonstrated that tissue ablation performance was contingent upon sweeping speed and maximized at slow sweeping speed due to longer laser-tissue interaction time and larger area coverage by the 532-nm light.

Micro-fractional ablative skin resurfacing with two novel erbium laser systems.

PubMed

Dierickx, Christine C; Khatri, Khalil A; Tannous, Zeina S; Childs, James J; Cohen, Richard H; Erofeev, Andrei; Tabatadze, David; Yaroslavsky, Ilya V; Altshuler, Gregory B

2008-02-01

Fractional ablation offers the potential benefits of full-surface ablative skin resurfacing while minimizing adverse effects. The purpose of this study was to evaluate the safety, damage profile, and efficacy of erbium fractional lasers. Histology from animal and human skin as well as clinical evaluations were conducted with erbium YAG (2,940 nm) and erbium YSGG (2,790 nm) fractional lasers varying pulse width, microbeam (microb) energy, number of passes, and stacking of pulses. Single-pulse treatment parameters from 1 to 12 mJ per 50-70 microm diameter microbeam and 0.25-5 milliseconds pulse widths produced microcolumns of ablation with border coagulation of up to 100 microm width and 450 microm depth. Stacking of pulses generated deeper microcolumns. Clinical observations and in vivo histology demonstrate rapid re-epithelization and limited adverse side effects. Facial treatments were performed in the periorbital and perioral areas using 1-8 passes of single and stacked pulses. Treatments were well-tolerated and subjects could resume their normal routine in 4 days. A statistically significant reduction in wrinkle scores at 3 months was observed for both periorbital and perioral wrinkles using blinded grading. For periorbital treatments of four passes or more, over 90% had > or =1 score wrinkle reduction (0-9 scale) and 42% had > or =2. For perioral wrinkles, over 50% had substantial improvements (> or =2). The clinical observations and histology findings demonstrate that micro-fractional ablative treatment with 2,790 and 2,940 nm erbium lasers resulted in safe and effective wrinkle reduction with minimal patient downtime. The depth and width of the ablated microcolumns and varying extent of surrounding coagulation can be controlled and used to design new treatment procedures targeted for specific indications and areas such as moderate to severe rhytides and photodamaged skin.

MoXy fiber with active cooling cap for bovine prostate vaporization with high power 200W 532 nm laser

NASA Astrophysics Data System (ADS)

Peng, Steven Y.; Kang, Hyun Wook; Pirzadeh, Homa; Stinson, Douglas

2011-03-01

A novel MoXyTM fiber delivery device with Active Cooling Cap (ACCTM) is designed to transmit up to 180W of 532 nm laser light to treat benign prostatic hyperplasia (BPH). Under such high power tissue ablation, effective cooling is key to maintaining fiber power transmission and ensuring the reliability of the fiber delivery device To handle high power and reduce fiber degradation, the MoXy fiber features a larger core size (750 micrometer) and an internal fluid channel to ensure better cooling of the fiber tip to prevent the cap from burning, detaching, or shattering during the BPH treatment. The internal cooling channel was created with a metal cap and tubing that surrounds the optical fiber. In this study MoXy fibers were used to investigate the effect of power levels of 120 and 200 W on in-vitro bovine prostate ablation using a 532 nm XPSTM laser system. For procedures requiring more than 100 kJ, the MoXy fiber at 200W removed tissue at twice the rate of the current HPS fiber at 120W. The fiber maintained a constant tissue vaporization rate during the entire tissue ablation process. The coagulation at 200W was about 20% thicker than at 120W. In conclusion, the new fibers at 200W doubled the tissue removal rate, maintained vaporization efficiency throughout delivery of 400kJ energy, and induced similar coagulation to the existing HPS fiber at 120W.

Bloodcurdling movies and measures of coagulation: Fear Factor crossover trial.

PubMed

Nemeth, Banne; Scheres, Luuk J J; Lijfering, Willem M; Rosendaal, Frits R

2015-12-16

To assess whether, as has been hypothesised since medieval times, acute fear can curdle blood. Crossover trial. Main meeting room of Leiden University's Department of Clinical Epidemiology, the Netherlands, converted to a makeshift cinema. 24 healthy volunteers aged ≤30 years recruited among students, alumni, and employees of the Leiden University Medical Center: 14 were assigned to watch a frightening (horror) movie followed by a non-threatening (educational) movie and 10 to watch the movies in reverse order. The movies were viewed more than a week apart at the same time of day and both lasted approximately 90 minutes. The primary outcome measures were markers, or "fear factors" of coagulation activity: blood coagulant factor VIII, D-dimer, thrombin-antithrombin complexes, and prothrombin fragments 1+2. The secondary outcome was participant reported fear experienced during each movie using a visual analogue fear scale. All participants completed the study. The horror movie was perceived to be more frightening than the educational movie on a visual analogue fear scale (mean difference 5.4, 95% confidence interval 4.7 to 6.1). The difference in factor VIII levels before and after watching the movies was higher for the horror movie than for the educational movie (mean difference of differences 11.1 IU/dL (111 IU/L), 95% confidence interval 1.2 to 21.0 IU/dL). The effect of either movie on levels of thrombin-antithrombin complexes, D-dimer, and prothrombin fragments 1+2 did not differ. Frightening (in this case, horror) movies are associated with an increase of blood coagulant factor VIII without actual thrombin formation in young and healthy adults. Trial registration ClinicalTrials.gov NCT02601053. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Subsurface thermal coagulation of tissues using near infrared lasers

NASA Astrophysics Data System (ADS)

Chang, Chun-Hung Jack

Noninvasive laser therapy is currently limited primarily to cosmetic dermatological applications such as skin resurfacing, hair removal, tattoo removal and treatment of vascular birthmarks. In order to expand applications of noninvasive laser therapy, deeper optical penetration of laser radiation in tissue as well as more aggressive cooling of the tissue surface is necessary. The near-infrared laser wavelength of 1075 nm was found to be the optimal laser wavelength for creation of deep subsurface thermal lesions in liver tissue, ex vivo, with contact cooling, preserving a surface tissue layer of 2 mm. Monte Carlo light transport, heat transfer, and Arrhenius integral thermal damage simulations were conducted at this wavelength, showing good agreement between experiment and simulations. Building on the initial results, our goal is to develop new noninvasive laser therapies for application in urology, specifically for treatment of female stress urinary incontinence (SUI). Various laser balloon probes including side-firing and diffusing fibers were designed and tested for both transvaginal and transurethral approaches to treatment. The transvaginal approach showed the highest feasibility. To further increase optical penetration depth, various types and concentrations of optical clearing agents were also explored. Three cadavers studies were performed to investigate and demonstrate the feasibility of laser treatment for SUI.

Pediatric Bilateral Blue Laser Pointer-Induced Maculopathy

PubMed Central

Raevis, Joseph; Shrier, Eric

2017-01-01

Background We report the first case of pediatric bilateral blue laser pointer maculopathy with complete resolution of visual symptoms. Case A 12-year-old boy presented with bilateral decreased visual acuity and central scotomata after blue laser pointer exposure. He was treated with a Medrol Dosepak and topical nonsteroidal anti-inflammatory drug (NSAID), with gradual visual acuity improved from 20/40 OU to 20/20 OU over 22 weeks, but with persistent evidence of outer retinal layer disruption from the external limiting membrane to the interdigitation zone. Conclusion Oral steroids and topical NSAIDs may be effective in improving visual outcomes in laser pointer maculopathy in the pediatric population. PMID:28611647

Clinical Application of Diode Laser (980 nm) in Maxillofacial Surgical Procedures.

PubMed

Aldelaimi, Tahrir N; Khalil, Afrah A

2015-06-01

For many procedures, lasers are now becoming the treatment of choice by both clinicians and patients, and in some cases, the standard of care. This clinical study was carried out at Department of Maxillofacial Surgery, Ramadi Teaching Hospital, Rashid Private Hospital and Razi Private Hospital, Anbar Health Directorate, Anbar Province, Iraq. A total of 32 patients including 22 (≈ 70%) male and 10 (≈ 30%) female with age range from 5 months to 34 years old. Chirolas 20 W diode laser emitting at 980 nm was used. Our preliminary clinical findings include sufficient hemostasis, coagulation properties, precise incision margin, lack of swelling, bleeding, pain, scar tissue formation and overall satisfaction were observed in the clinical application. The clinical application of the diode (980 nm) laser in maxillofacial surgery proved to be of beneficial effect for daily practice and considered practical, effective, easy to used, offers a safe, acceptable, and impressive alternative for conventional surgical techniques.

Laserthermia: a new computer-controlled contact Nd: YAG system for interstitial local hyperthermia.

PubMed

Daikuzono, N; Suzuki, S; Tajiri, H; Tsunekawa, H; Ohyama, M; Joffe, S N

1988-01-01

Contact Nd:YAG laser surgery is assuming a greater importance in endoscopic and open surgery, allowing coagulation, cutting, and vaporization with greater precision and safety. A new contact probe allows a wider angle of irradiation and diffusion of low-power laser energy (less than 5 watts), using the interstitial technique for producing local hyperthermia. Temperature sensors that monitor continuously can be placed directly into the surrounding tissue or tumor. Using a computer program interfaced with the laser and sensors, a controlled and stable temperature (e.g., 42 degrees C) can be produced in a known volume of tissue over a prolonged period of time (e.g., 20-40 min). This new laserthermia system, using a single low-power Nd:YAG laser for interstitial local hyperthermia, may offer many new advantages in the experimental treatment and clinical management of carcinoma. A multiple system is now being developed.

Tissue dissection using a 1470-nm diode laser and laparoscopic prototype

NASA Astrophysics Data System (ADS)

Chang, Chun-Hung; Hammerland, John; Nau, William H.; Fried, Nathaniel M.

2017-02-01

A continuous-wave, 40 Watt, 1470 nm laser was explored for rapid and precise dissection of porcine mesentery fascia and liver tissues, ex vivo. Laser energy was delivered through a 550-μm-core optical fiber inside a 5-mm-OD, laparoscopic probe, with detachable, 2 mm, sapphire ball rolling tip. Fascia tissue was cleanly dissected with scanning rates from 2.0 - 4.5 mm/s using 16 - 31W. Fascia collateral thermal damage measured as low as 180 +/- 50 μm at 4.5 mm/s scan speed. Porcine liver ablation crater depth measured up to 1010 +/- 220 μm with 30 W at 2.0 mm/s or as shallow as 80 +/- 30 μm with 10 W at 10 mm/s. Peak temperatures reached 130 °C at ball tip and 75 °C on metal jaws. The 1470-nm laser and probe show promise for laparoscopic tissue cutting and coagulation.

Optical sensing of anticoagulation status: Towards point-of-care coagulation testing

PubMed Central

Tripathi, Markandey M.; Hajjarian, Zeinab; Van Cott, Elizabeth M.; Nadkarni, Seemantini K.

2017-01-01

Anticoagulant overdose is associated with major bleeding complications. Rapid coagulation sensing may ensure safe and accurate anticoagulant dosing and reduce bleeding risk. Here, we report the novel use of Laser Speckle Rheology (LSR) for measuring anticoagulation and haemodilution status in whole blood. In the LSR approach, blood from 12 patients and 4 swine was placed in disposable cartridges and time-varying intensity fluctuations of laser speckle patterns were measured to quantify the viscoelastic modulus during clotting. Coagulation parameters, mainly clotting time, clot progression rate (α-angle) and maximum clot stiffness (MA) were derived from the clot viscoelasticity trace and compared with standard Thromboelastography (TEG). To demonstrate the capability for anticoagulation sensing in patients, blood samples from 12 patients treated with warfarin anticoagulant were analyzed. LSR clotting time correlated with prothrombin and activated partial thromboplastin time (r = 0.57–0.77, p<0.04) and all LSR parameters demonstrated good correlation with TEG (r = 0.61–0.87, p<0.04). To further evaluate the dose-dependent sensitivity of LSR parameters, swine blood was spiked with varying concentrations of heparin, argatroban and rivaroxaban or serially diluted with saline. We observed that anticoagulant treatments prolonged LSR clotting time in a dose-dependent manner that correlated closely with TEG (r = 0.99, p<0.01). LSR angle was unaltered by anticoagulation whereas TEG angle presented dose-dependent diminution likely linked to the mechanical manipulation of the clot. In both LSR and TEG, MA was largely unaffected by anticoagulation, and LSR presented a higher sensitivity to increased haemodilution in comparison to TEG (p<0.01). Our results establish that LSR rapidly and accurately measures the response of various anticoagulants, opening the opportunity for routine anticoagulation monitoring at the point-of-care or for patient self-testing. PMID:28771571

Automated wavelet denoising of photoacoustic signals for circulating melanoma cell detection and burn image reconstruction.

PubMed

Holan, Scott H; Viator, John A

2008-06-21

Photoacoustic image reconstruction may involve hundreds of point measurements, each of which contributes unique information about the subsurface absorbing structures under study. For backprojection imaging, two or more point measurements of photoacoustic waves induced by irradiating a biological sample with laser light are used to produce an image of the acoustic source. Each of these measurements must undergo some signal processing, such as denoising or system deconvolution. In order to process the numerous signals, we have developed an automated wavelet algorithm for denoising signals. We appeal to the discrete wavelet transform for denoising photoacoustic signals generated in a dilute melanoma cell suspension and in thermally coagulated blood. We used 5, 9, 45 and 270 melanoma cells in the laser beam path as test concentrations. For the burn phantom, we used coagulated blood in 1.6 mm silicon tube submerged in Intralipid. Although these two targets were chosen as typical applications for photoacoustic detection and imaging, they are of independent interest. The denoising employs level-independent universal thresholding. In order to accommodate nonradix-2 signals, we considered a maximal overlap discrete wavelet transform (MODWT). For the lower melanoma cell concentrations, as the signal-to-noise ratio approached 1, denoising allowed better peak finding. For coagulated blood, the signals were denoised to yield a clean photoacoustic resulting in an improvement of 22% in the reconstructed image. The entire signal processing technique was automated so that minimal user intervention was needed to reconstruct the images. Such an algorithm may be used for image reconstruction and signal extraction for applications such as burn depth imaging, depth profiling of vascular lesions in skin and the detection of single cancer cells in blood samples.

Imaging analyses of coagulation-dependent initiation of fibrinolysis on activated platelets and its modification by thrombin-activatable fibrinolysis inhibitor.

PubMed

Brzoska, Tomasz; Suzuki, Yuko; Sano, Hideto; Suzuki, Seiichirou; Tomczyk, Martyna; Tanaka, Hiroki; Urano, Tetsumei

2017-04-03

Using intravital confocal microscopy, we observed previously that the process of platelet phosphatidylserine (PS) exposure, fibrin formation and lysine binding site-dependent plasminogen (plg) accumulation took place only in the centre of thrombi, not at their periphery. These findings prompted us to analyse the spatiotemporal regulatory mechanisms underlying coagulation and fibrinolysis. We analysed the fibrin network formation and the subsequent lysis in an in vitro experiment using diluted platelet-rich plasma supplemented with fluorescently labelled coagulation and fibrinolytic factors, using confocal laser scanning microscopy. The structure of the fibrin network formed by supplemented tissue factor was uneven and denser at the sites of coagulation initiation regions (CIRs) on PS-exposed platelets. When tissue-type plasminogen activator (tPA; 7.5 nM) was supplemented, labelled plg (50 nM) as well as tPA accumulated at CIRs, from where fibrinolysis started and gradually expanded to the peripheries. The lysis time at CIRs and their peripheries (50 µm from the CIR) were 27.9 ± 6.6 and 44.4 ± 9.7 minutes (mean ± SD, n=50 from five independent experiments) after the addition of tissue factor, respectively. Recombinant human soluble thrombomodulin (TMα; 2.0 nM) attenuated the CIR-dependent plg accumulation and strongly delayed fibrinolysis at CIRs. A carboxypeptidase inhibitor dose-dependently enhanced the CIR-dependent fibrinolysis initiation, and at 20 µM it completely abrogated the TMα-induced delay of fibrinolysis. Our findings are the first to directly present crosstalk between coagulation and fibrinolysis, which takes place on activated platelets' surface and is further controlled by thrombin-activatable fibrinolysis inhibitor (TAFI).

Characterization of photoacoustic sources in tissue using time domain measurements

NASA Astrophysics Data System (ADS)

Viator, John Andrew

Photoacoustic phenomenon in tissue and tissue phantoms is investigated with the particular goal of discrimination of diseased and healthy tissue. Propagation of broadband photoacoustic sources in tissue phantoms is studied with emphasis on attenuation, dispersion, and diffraction. Attenuation of photoacoustic waves induced by a circular laser spot on an absorber/air interface is modeled by the on-axis approximation of the acoustic field of a baffled piston source. Dispersion is studied in a diffraction free situation, where the disk of irradiation was created by a 5 mm laser spot on a 200 cm -1 solution. The genesis of diffraction in an absorbing solution was displayed by showing the merging of a boundary wave with a plane wave from a circular laser spot on an absorbing solution. Depth profiling of absorbing tissue phantoms and stained tissue was shown using a photoacoustic method. Acrylamide gels with layers of different optical absorption and stained elastin biomaterials were irradiated with stress confined laser pulses. The resulting acoustic waves were detected with a lithium niobate wideband acoustic transducer and processed in an algorithm to determine absorption coefficient as a function of depth. Spherical photoacoustic sources were generated in optically clear and turbid tissue phantoms. Propagation time and acoustic pulse duration were used to determine location and size, respectively. The photoacoustic sources were imaged using a multiplicative backprojection scheme. Image sources from acoustic boundaries were detected and dipole sources were detected and imaged. Finally an endoscopic photoacoustic probe was designed, built, and tested for use in determining treatment depth after palliative photodynamic therapy of esophageal cancer. The probe was less than 2.5 mm in diameter and consisted of a side firing 600 mum optical fiber to deliver laser energy and a 890 mum diameter, side viewing piezoelectric detector. The sensitivity of the probe was determined. The probe was also tested on coagulated and non-coagulated liver, ex vivo and on normally perfused and underperfused human skin, in vivo.

Laser CO2 tonsillotomy versus argon plasma coagulation (APC) tonsillotomy: A retrospective study with 10-year follow-up.

PubMed

Papaspyrou, Giorgos; Linxweiler, Maximilian; Knöbber, Dirk; Schick, Bernhard; Al Kadah, Basel

2017-01-01

Tonsillotomy is increasingly gaining acceptance as the treatment for tonsillar hyperplasia resulting in obstructive symptoms. The aim of this study was to compare the long-term results of CO 2 laser tonsillotomy with those of argon plasma coagulation (APC) tonsillotomy. The data of 64 children, aged 2-10 years (mean 4.7 years), treated in the Department of Otolaryngology, Head and Neck Surgery, in Homburg, Germany with APC (36 patients) or CO 2 laser (28 patients) for tonsillar hyperplasia between June 2004 and December 2004 were available for analysis. Forty-five (APC: 26 patients, CO 2 : 19 patients) of the 64 patients (70.3%) could be contacted and were available for follow-up in a telephone survey conducted 10 years after surgery. The mean operation time was 17 min (range 10-25 min) in the APC group and 23 min (range 13-32 min) in the CO 2 group (p = 0.0003). No case of intra- or postoperative bleeding was documented. One minor intraoperative complication in the form of a superficial lip burn was documented in the APC group. During the minimum 10 years of follow-up, 1 patient treated with APC underwent a surgical revision because of tonsillar regrowth, whereas in the group of patients treated with CO 2 , no surgical revision was needed. Regarding the parents' assessment of their children's symptoms, 89.4% of the parents of the CO 2 laser group and 84.6% of the parents of the APC group reported that the overall long-term operation results of their children to be "very satisfying." Regarding complications, the need for secondary tonsillectomy, and parents' satisfaction, no statistically significant differences were found. Both CO 2 laser tonsillotomy and APC tonsillotomy are safe procedures leading to very satisfying results with respect to intra- and postoperative complications. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Ablation of dermal and mucosal lesions with a new CO2 laser application system

NASA Astrophysics Data System (ADS)

Jovanovic, Sergije; Sedlmaier, Benedikt W.; Fuehrer, Ariane

1997-05-01

Laser treatment of skin changes has become common practice in recent years. The high absorption of the wavelength of the carbon-dioxide laser (10600 nm) is responsible for its low penetration depth in biological tissue. Shortening the exposure time minimizes thermic side effects such as carbonization and coagulation. This effect can be achieved with the SilkTouchTM scanner 767, since the focused laser beam is moved over a defined area by rapidly rotating mirrors. This enables controlled and reliable removal of certain dermal lesions, particularly hypertrophic scars, scars after common acne, wrinkles, rhinophyma and benign neoplasms like verruca vulgaris. Cosmetically favorable reepithelialization of the lasered surfaces results within a very short period of time. Benign mucosal changes of the upper aerodigestive tract can also be treated. Ablation is less traumatic for papillomas, fibromas, hyperplasias in the area of Waldeyer's tonsillar ring and certain laryngotracheal pathologies. Clinical examples demonstrate the advantages of this new mode of application.

Lasers in Ophthalmology

PubMed Central

Rock, William

1986-01-01

Lasers provide a convenient source of focused light energy that can be delivered to a target and, specifically, can do one of two things in the eye. Lasers can create a thermal lesion, that is, a burn, in the same way that light from the sun that is focused with a magnifying glass will burn paper. This thermal lesion can create a scar or hole in the target tissue. In photocoagulation techniques depend on the thermal effect, i.e., the absorption characteristics of the tissues to be coagulated indicate the wavelength to be chosen. The three important ocular light absorbers are melanin, hemoglobin and xanthophyll. For anterior segment work, melanin in the iris and trabecular meshwork is the most important absorber and hemoglobin in blood is the second most important. In retinal work, hemoglobin and xanthophyll absorption are the most important absorbers. The second type of laser effect is achieved with very short duration, high-powered lasers such as the Q-switched neodymium YAG. Non-thermal effects cause disruption of any target tissue either transparent or opaque. PMID:21267103

Macular Structures, Optical Components, and Visual Acuity in Preschool Children after Intravitreal Bevacizumab or Laser Treatment.

PubMed

Lee, Yung-Sung; See, Lai-Chu; Chang, Shu-Hao; Wang, Nan-Kai; Hwang, Yih-Shiou; Lai, Chi-Chun; Chen, Kuan-Jen; Wu, Wei-Chi

2018-05-10

To investigate the macular structures, optical components, and visual acuity in preschool-aged children with a history of type I retinopathy of prematurity who underwent either intravitreal bevacizumab (IVB), laser, or a combination of treatments. Comparative interventional case series. A referred medical center in Taiwan. 80 eyes from 42 patients (33 IVB-treated eyes from 17 children, 24 laser-treated eyes from 13 children, and 23 laser + IVB-treated eyes from 12 children). Spectral-domain optical coherence tomography. The retinal thickness in the foveal area and the associated morphologic changes in foveal depression. Compared with the laser-treated and laser + IVB-treated eyes, the IVB-treated eyes had less myopia and deeper anterior chamber depths but presented similar axial lengths and corneal curvatures (P = .001, .002, .95 and .16, respectively). The IVB-treated eyes had significantly thinner foveal, parafoveal, and perifoveal retinal thicknesses (P < .01 for all) and a higher incidence of foveal depression than the laser- or laser + IVB-treated eyes. The macular and subfoveal choroidal thicknesses did not differ among the groups (P = .21 and .63, respectively). Moreover, compared with the eyes treated with laser or laser + IVB, the IVB-treated eyes had better uncorrected visual acuity, although a significant difference was not observed in best-corrected visual acuity (P = .008 and .29, respectively). Compared with laser therapy, IVB-treated eyes were associated with deeper anterior chamber depths and thinner foveal, parafoveal and perifoveal thicknesses. Moreover, these IVB-treated eyes had less refractive errors and better uncorrected visual acuity. Copyright © 2018. Published by Elsevier Inc.

Carbon dioxide laser for de-epithelialization of periodontal flaps.

PubMed

Centty, I G; Blank, L W; Levy, B A; Romberg, E; Barnes, D M

1997-08-01

Regeneration of mineralized and soft connective tissue components of the attachment apparatus is the main goal in the treatment of periodontal diseases. Often, apical migration of epithelium (long junctional epithelium) effectively prevents the formation of bone and connective tissue attachment after periodontal surgery. The purpose of the present study was to compare conventional periodontal surgery combined with carbon dioxide laser and conventional periodontal surgery alone with respect to epithelial elimination and degree of necrosis of mucoperiosteal flaps. After signing a consent form, five patients with at least two comparable bilateral periodontal defects needing pocket elimination surgery participated in this study. The investigators randomly divided each side into test and control sites. Each patient received oral hygiene instruction and initial therapy prior to surgery. At surgery, the test site received a sulcular incision and carbon dioxide laser de-epithelialization of the outer and inner aspects of the flap. The control group received reverse bevel incision only. The surgeon performed open flap debridement on all teeth. At the time of surgery, the surgeon did a biopsy of each site and submitted specimens for histologic evaluation. A matched pairs t-test was used to analyze the data. The results show significant differences between the carbon dioxide laser and reverse bevel incision with respect to sulcular (P < or = 0.025) and gingival (external) (P < or = 0.01) flap surface epithelial elimination and tissue necrosis (P < or = 0.005). These results should be replicated with a larger number of subjects. The carbon dioxide laser eliminated sulcular and gingival (external) epithelium without disturbing underlying connective tissue. This finding supports the concept that the carbon dioxide wavelength has little or no effect on tissues beyond the target. However, neither laser nor blade eliminated all the epithelium. Researchers observed chronic inflammation in the control and test sites, with a predominance of plasma cells. Lining the sulcular and gingival (external) lased areas, investigators found coagulation necrosis covered by fibrin and coagulated blood. The laser appears to effectively remove epithelium at the time of surgery; however, future long-term, well-controlled quantitative histologic studies are needed to evaluate the effect of repeated carbon dioxide laser de-epithelialization of the gingival (external) surface of mucoperiosteal flaps at intervals during the healing period.

Infrared coagulation versus rubber band ligation in early stage hemorrhoids.

PubMed

Gupta, P J

2003-10-01

The ideal therapy for early stages of hemorrhoids is always debated. Some are more effective but are more painful, others are less painful but their efficacy is also lower. Thus, comfort or efficacy is a major concern. In the present randomized study, a comparison is made between infrared coagulation and rubber band ligation in terms of effectiveness and discomfort. One hundred patients with second degree bleeding piles were randomized prospectively to either rubber band ligation (N = 54) or infrared coagulation (N = 46). Parameters measured included postoperative discomfort and pain, time to return to work, relief in incidence of bleeding, and recurrence rate. The mean age was 38 years (range 19-68 years). The mean duration of disease was 17.5 months (range 12 to 34 months). The number of male patients was double that of females. Postoperative pain during the first week was more intense in the band ligation group (2-5 vs 0-3 on a visual analogue scale). Post-defecation pain was more intense with band ligation and so was rectal tenesmus (P = 0.0059). The patients in the infrared coagulation group resumed their duties earlier (2 vs 4 days, P = 0.03), but also had a higher recurrence or failure rate (P = 0.03). Thus, we conclude that band ligation, although more effective in controlling symptoms and obliterating hemorrhoids, is associated with more pain and discomfort to the patient. As infrared coagulation can be conveniently repeated in case of recurrence, it could be considered to be a suitable alternative office procedure for the treatment of early stage hemorrhoids.

Dissimilarity of increased phosphatidylserine-positive microparticles and associated coagulation activation in acute coronary syndromes.

PubMed

Liu, Yan; He, Zhangxiu; Zhang, Yan; Dong, Zengxiang; Bi, Yayan; Kou, Junjie; Zhou, Jin; Shi, Jialan

2016-08-01

We evaluated cellular origin, numbers, and procoagulant activity of phosphatidylserine-positive microparticles (MPs) among subgroups in acute coronary syndromes (ACS). Parameters were measured on admission, days 1 (within 24 h of admission), 2, 3, and 7. All ST-elevated myocardial infarction (STEMI) patients presented more than 3 h from symptom onset and received fibrinolysis treatment; controls included unstable angina and non-STEMI patients as well as healthy controls. Phosphatidylserine-positive MPs were detected by flow cytometry, whereas procoagulant activity was assessed by coagulation time, purified coagulation complex assays, and fibrin formation. MP-induced fibrins were visualized by confocal microscopy. On admission, the total MP count was ∼2.5-fold higher in the ACS groups compared with the healthy controls (P<0.05), primarily originating from platelets and endothelial cells, and there were no significant differences among ACS subgroups. Specifically, leukocyte-derived and erythrocyte-derived MPs were higher in the STEMI group compared with unstable angina and non-STEMI groups (both P<0.05). Further, MPs from the ACS groups reduced coagulation time by 27.5% and induced intrinsic and extrinsic FXase, prothrombinase, and fibrin formation by 2.8-, 2.3-, 2.5-, and 1.7-fold, respectively (P<0.05 for all), whereas blocking phosphatidylserine with lactadherin inhibited ∼70% of procoagulant activity. MP number and concomitant coagulation decreased significantly by day 2 and continued to decrease gradually during the recovery period. This study shows that MP characteristics from circulating blood may be used as prognostic indicators to reflect the origin cell of activation and thrombophilic states found in ACS subgroups.

Black Carbon Aging from SOA Coatings and Coagulation with Diesel BC Emissions during SAAS at the PNNL Environmental Chamber

NASA Astrophysics Data System (ADS)

Aiken, A. C.; Liu, S.; Dubey, M. K.; Zaveri, R. A.; Shilling, J. E.; Gourihar, K.; Pekour, M. S.; Subramanian, R.; Zelenyuk, A.; Wilson, J. M.; Mazzoleni, C.; China, S.; Sharma, N.

2014-12-01

Black carbon (BC) is considered to be potentially the 2nd most important global warming factor behind CO2 (Bond et al., 2013). Uncertainties exist due to BC morphology and mixing state on the extent of the warming that it causes, e.g. Cappa et al., 2012. Core-shell BC is expected to enhance absorption by up to a factor of 2, but has yet to be observed to this extent from ambient data. Experiments were conducted during the Soot Aerosol Aging Study (SAAS) Laboratory Campaign at Pactific Northwest National Laboratory's Environmental Chamber in the winter of 2013-2014 to investigate the relationship between coatings and enhancements from diesel emissions. Direct on-line measurements were made with the single particle soot photometer (SP2) from fresh and aged BC from coating and coagulation experiments with secondary organic aerosol (SOA) formed in the chamber. BC measurements are coupled with photoactoustic measurements spanning the visible region to probe BC enhancements when mixed with SOA. Here we focus on the enhancements at 781 nm, that are tracked throughout SOA growth on BC, as determined from SP2 coating thicknesses. Thermal denuder (TD) experiments are conducted and enhancements are calculated from two different methods that agree well with each other, confirming the observed results. BC measurements are also compared with co-located measurements from SPLAT-II and filter analysis using SEM and TEM. BC coagulated with SOA produces minimal absorption enhancement values, whereas coatings are observed to have significant enhancement values at 300 degrees C, e.g. 1.3 for thickly coated BC. BC particles were coagulated with SOA in the chamber since this morphology has been observed in wildfire emissions (Sedlacek et al., 2012). Since we did not observe appreciable enhancements for the coagulated BC, we expect that ambient emissions dominated by this particle type to have enhancements due to other sources, such as brown carbon (BrC) that is often co-emitted (Saleh et al., 2014). We also observed thickly coated BC that is not detected by the SP2 when the coatings are too thick for the laser to evaporate the coating and for the BC core to receive enough energy from the laser to incandesce. This noted caveat warrants more research to determine how prevalent this BC particle type is and how it would be expected to impact climate.

Visualization of laser tattoo removal treatment effects in a mouse model by two-photon microscopy

PubMed Central

Jang, Won Hyuk; Yoon, Yeoreum; Kim, Wonjoong; Kwon, Soonjae; Lee, Seunghun; Song, Duke; Choi, Jong Woon; Kim, Ki Hean

2017-01-01

Laser tattoo removal is an effective method of eliminating tattoo particles in the skin. However, laser treatment cannot always remove the unwanted tattoo completely, and there are risks of either temporary or permanent side effects. Studies using preclinical animal models could provide detailed information on the effects of laser treatment in the skin, and might help to minimize side effects in clinical practices. In this study, two-photon microscopy (TPM) was used to visualize the laser treatment effects on tattoo particles in both phantom specimens and in vivo mouse models. Fluorescent tattoo ink was used for particle visualization by TPM, and nanosecond (ns) and picosecond (ps) lasers at 532 nm were used for treatment. In phantom specimens, TPM characterized the fragmentation of individual tattoo particles by tracking them before and after the laser treatment. These changes were confirmed by field emission scanning electron microscopy (FE-SEM). TPM was used to measure the treatment efficiency of the two lasers at different laser fluences. In the mouse model, TPM visualized clusters of tattoo particles in the skin and detected their fragmentation after the laser treatment. Longitudinal TPM imaging observed the migration of cells containing tattoo particles after the laser treatment. These results show that TPM may be useful for the assessment of laser tattoo removal treatment in preclinical studies. PMID:28856046

Optoacoustic detection of thermal lesions

NASA Astrophysics Data System (ADS)

Arsenault, Michel G.; Kolios, Michael C.; Whelan, William M.

2009-02-01

Minimally invasive thermal therapy is being investigated as an alternative cancer treatment. It involves heating tissues to greater than 55°C over a period of a few minutes, which results in tissue coagulation. Optoacoustic (OA) imaging is a new imaging technique that involves exposing tissues to pulsed light and detecting the acoustic waves that are generated. In this study, adult bovine liver tissue samples were heated using continuous wave laser energy for various times, then scanned using an optoacoustic imaging system. Large optoacoustic signal variability was observed in the native tissue prior to heating. OA signal amplitude increased with maximum tissue temperature achieved, characterized by a correlation coefficient of 0.63. In this study we show that there are detectable changes in optoacoustic signal strength that arise from tissue coagulation, which demonstrates the potential of optoacoustic technology for the monitoring of thermal therapy delivery.

Water tunnel flow visualization using a laser

NASA Technical Reports Server (NTRS)

Beckner, C.; Curry, R. E.

1985-01-01

Laser systems for flow visualization in water tunnels (similar to the vapor screen technique used in wind tunnels) can provide two-dimensional cross-sectional views of complex flow fields. This parametric study documents the practical application of the laser-enhanced visualization (LEV) technique to water tunnel testing. Aspects of the study include laser power levels, flow seeding (using flourescent dyes and embedded particulates), model preparation, and photographic techniques. The results of this study are discussed to provide potential users with basic information to aid in the design and setup of an LEV system.

Wound repair in rat urinary bladder following electrocautery or holmium laser incision

NASA Astrophysics Data System (ADS)

Venzi, Giordano; Schmidlin, Franz R.; Gabbiani, Giulio; Delacretaz, Guy P.; Pittet, Brigitte; Leisinger, Hans-Juerg; Iselin, Christoph E.

1999-06-01

Woundhealing is a complex phenomenon which varies according the type of tissue but is also depending from the type of tissue injury. Electrocautery mainly induces coagulation necrosis while thermal damages induced by the Holmium laser primarily lead to tissue vaporization which may induce less tissue injury. The aim of this study was to evaluate the healing process of the Holmium laser induced lesions compared to electrocautery induced lesions in urothelial tissue by assessing the inflammatory response and myofibroblast behavior in sequential healing phases. A surgical wound was created in the urinary rat bladder of 32 rats either by electrocautery or by laser (N=16). The inflammatory response, the total lesion depth and the myofibroblast activity during woundhealing was then analyzed on a qualitative basis on days 0/2/4/8. The overall inflammatory response was comparable in both groups up to days two and four. However, at day eight less cellular inflammatory reaction and less myofibroblast activity was found in the specimen of lesions created by the Holmium laser. These results suggest that wound repair may be a less invasive process after Holmium laser than electrocautery.

Infrared thermal measurements of laser soft tissue ablation as a function of air/water coolant for Nd:YAG and diode lasers

NASA Astrophysics Data System (ADS)

Gekelman, Diana; Yamamoto, Andrew; Oto, Marvin G.; White, Joel M.

2003-06-01

The purpose of this investigation was to measure the maximum temperature at the Nd:YAG and Diode lasers fiberoptic tips as a function of air/water coolant, during soft tissue ablation in pig jaws. A pulsed Nd:YAG laser (1064nm) and a Diode laser (800-830 nm) were used varying parameters of power, conditioning or not of the fiber tip, under 4 settings of air/water coolant. The maximum temperature at the fiber tip was measured using an infra-red camera and the interaction of the fiber with the porcine soft tissue was evaluated. A two-factor ANOVA was used for statistical analysis (p<=0.05). Nd:YAG laser interaction with soft tissues produced temperatures levels directly proportional to power increase, but the conditioning of the fiber tip did not influence the temperature rise. On the other hand, conditioning of the fiber tip did influence the temperature rise for Diode laser. The addition of air/water coolant, for both lasers, did not promote temperature rise consistent with cutting and coagulation of porcine soft tissue. Laser parameters affect the fiberoptic surface temperature, and the addition of air/water coolant significantly lowered surface temperature on the fiberoptic tip for all lasers and parameters tested.

A Method for Medical Diagnosis Based on Optical Fluence Rate Distribution at Tissue Surface

PubMed Central

Hamdy, Omnia; El-Azab, Jala; Al-Saeed, Tarek A.; Hassan, Mahmoud F.

2017-01-01

Optical differentiation is a promising tool in biomedical diagnosis mainly because of its safety. The optical parameters’ values of biological tissues differ according to the histopathology of the tissue and hence could be used for differentiation. The optical fluence rate distribution on tissue boundaries depends on the optical parameters. So, providing image displays of such distributions can provide a visual means of biomedical diagnosis. In this work, an experimental setup was implemented to measure the spatially-resolved steady state diffuse reflectance and transmittance of native and coagulated chicken liver and native and boiled breast chicken skin at 635 and 808 nm wavelengths laser irradiation. With the measured values, the optical parameters of the samples were calculated in vitro using a combination of modified Kubelka-Munk model and Bouguer-Beer-Lambert law. The estimated optical parameters values were substituted in the diffusion equation to simulate the fluence rate at the tissue surface using the finite element method. Results were verified with Monte-Carlo simulation. The results obtained showed that the diffuse reflectance curves and fluence rate distribution images can provide discrimination tools between different tissue types and hence can be used for biomedical diagnosis. PMID:28930158

A Method for Medical Diagnosis Based on Optical Fluence Rate Distribution at Tissue Surface.

PubMed

Hamdy, Omnia; El-Azab, Jala; Al-Saeed, Tarek A; Hassan, Mahmoud F; Solouma, Nahed H

2017-09-20

Optical differentiation is a promising tool in biomedical diagnosis mainly because of its safety. The optical parameters' values of biological tissues differ according to the histopathology of the tissue and hence could be used for differentiation. The optical fluence rate distribution on tissue boundaries depends on the optical parameters. So, providing image displays of such distributions can provide a visual means of biomedical diagnosis. In this work, an experimental setup was implemented to measure the spatially-resolved steady state diffuse reflectance and transmittance of native and coagulated chicken liver and native and boiled breast chicken skin at 635 and 808 nm wavelengths laser irradiation. With the measured values, the optical parameters of the samples were calculated in vitro using a combination of modified Kubelka-Munk model and Bouguer-Beer-Lambert law. The estimated optical parameters values were substituted in the diffusion equation to simulate the fluence rate at the tissue surface using the finite element method. Results were verified with Monte-Carlo simulation. The results obtained showed that the diffuse reflectance curves and fluence rate distribution images can provide discrimination tools between different tissue types and hence can be used for biomedical diagnosis.

Diode Laser for Laryngeal Surgery: a Systematic Review.

PubMed

Arroyo, Helena Hotz; Neri, Larissa; Fussuma, Carina Yuri; Imamura, Rui

2016-04-01

Introduction The diode laser has been frequently used in the management of laryngeal disorders. The portability and functional diversity of this tool make it a reasonable alternative to conventional lasers. However, whether diode laser has been applied in transoral laser microsurgery, the ideal parameters, outcomes, and adverse effects remain unclear. Objective The main objective of this systematic review is to provide a reliable evaluation of the use of diode laser in laryngeal diseases, trying to clarify its ideal parameters in the larynx, as well as its outcomes and complications. Data Synthesis We included eleven studies in the final analysis. From the included articles, we collected data on patient and lesion characteristics, treatment (diode laser's parameters used in surgery), and outcomes related to the laser surgery performed. Only two studies were prospective and there were no randomized controlled trials. Most of the evidence suggests that the diode laser can be a useful tool for treatment of different pathologies in the larynx. In this sense, the parameters must be set depending on the goal (vaporization, section, or coagulation) and the clinical problem. The literature lacks studies on the ideal parameters of the diode laser in laryngeal surgery. The available data indicate that diode laser is a useful tool that should be considered in laryngeal surgeries. Thus, large, well-designed studies correlated with diode compared with other lasers are needed to better estimate its effects.

Diode Laser for Laryngeal Surgery: a Systematic Review

PubMed Central

Arroyo, Helena Hotz; Neri, Larissa; Fussuma, Carina Yuri; Imamura, Rui

2016-01-01

Introduction The diode laser has been frequently used in the management of laryngeal disorders. The portability and functional diversity of this tool make it a reasonable alternative to conventional lasers. However, whether diode laser has been applied in transoral laser microsurgery, the ideal parameters, outcomes, and adverse effects remain unclear. Objective The main objective of this systematic review is to provide a reliable evaluation of the use of diode laser in laryngeal diseases, trying to clarify its ideal parameters in the larynx, as well as its outcomes and complications. Data Synthesis We included eleven studies in the final analysis. From the included articles, we collected data on patient and lesion characteristics, treatment (diode laser's parameters used in surgery), and outcomes related to the laser surgery performed. Only two studies were prospective and there were no randomized controlled trials. Most of the evidence suggests that the diode laser can be a useful tool for treatment of different pathologies in the larynx. In this sense, the parameters must be set depending on the goal (vaporization, section, or coagulation) and the clinical problem. Conclusion: The literature lacks studies on the ideal parameters of the diode laser in laryngeal surgery. The available data indicate that diode laser is a useful tool that should be considered in laryngeal surgeries. Thus, large, well-designed studies correlated with diode compared with other lasers are needed to better estimate its effects. PMID:27096024

A new multipurpose CO2 laser therapy instrument.

PubMed

Peng, X

1995-02-01

A new multipurpose CO2 laser therapy instrument has been developed. It is a highly efficient medical instrument. By use of high laser power density to coagulate, evaporate, and cut body tissue on the nidus, the operation can be controlled and has obvious curative effects. Unlike other kinds of CO2 laser therapy instruments, this device has an advanced switching power supply (SPS) and red guiding light system. With an overcurrent protective device, an overvoltage protective device, and a high-voltage shield device, it provides efficiency, stability, reliability, and low loss. The plastic casing does not leak electricity and the film switches are designed for clinical practice convenience. Additionally, the laser power is numerically displayed and can be set prior to the procedure. The distinct visible guiding light of the laser output makes the operation more convenient and accurate. Because of this unique design and properties, it is a leading model in China. The instrument can be widely used for surgery, gynecology, dermatology, and otolaryngology. The radiation therapy of low laser power density has the effect of being antiinflamatory, analgesic, and antipruritic, and promotes cure of the epithelium. Moreover, it is effective to treat all sorts of sprains, scapulohumeral periarthritis, arthritis, sciatica, and surface ulcers.

[System continuity and energy distribution in laser-induced thermo therapy (LITT)].

PubMed

Pech, M; Werk, M; Beck, A; Stohlmann, A; Ricke, J

2002-06-01

Evaluation of the continuity and energy distribution of a laser system for laser-induced thermo therapy. For evaluation of the continuity of laser optical devices, laser generating units and optical fibers of three different manufactures (Dornier, Hüttinger, Somatex), we used the equipment to generate a laser beam of 25 Watt for 60 minutes. Measurements of the applied energy were done sequentially with two MY Test (Fa. Hüttinger) units. We also performed two in vitro ablations of animal liver tissue with different fiber optics [Mikrodom A 13-0540, Microflexx REF A 13-0561 (Hüttinger), Diffusor-Tip H-6111-T 3, Diffusor H-6111-T 4 (Dornier), Somaflex-Diffusor (Somatex)] over 20 minutes at- an energy flow of 25 J per second. We then evaluated the geometry of coagulation. The different equipment used for our tests showed differences of a maximum of 10 %. Some components did not work properly in certain configurations even though the manufacturer assured it would. We saw significant differences in the ablation characteristics of the different fiber optics, especially in axial and frontal directions. Knowledge of the different characteristics in energy distribution and ablation characteristics are an important factor in performing a successful laser-induced thermo therapy.

Microscopic analysis of structural changes in diode-laser-welded corneal stroma

NASA Astrophysics Data System (ADS)

Matteini, Paolo; Rossi, Francesca; Menabuoni, Luca; Pini, Roberto

2007-02-01

Diode laser welding of the cornea is a technique used to provide immediate sealing of corneal wounds: the cut is stained with a water solution of Indocyanine Green and is then irradiated with an 810 nm laser at low power densities (12-16 W/cm2), which induces a localized heating of the stroma in the range 55-66 °C range. In this study, we present a microscopic analysis aimed at evaluating the structural modifications induced in the stromal collagen of pig eyes during the laser welding of corneal wounds. Cornea samples obtained from twenty freshly-enucleated eyes were cut with a pre-calibrated knife and subjected to the laser welding procedure. Histological slices of the laser-welded stroma were examined by means of optical and transmission electron microscopy. These analyses indicated that bridges of lamellar structures crossed the wound edges with no presence of a coagulation effect. After laser welding, collagen fibrils appeared differently oriented among themselves in comparison with those of the control samples, but with similar mean fibril diameters. The laser-induced effect appeared to be confined to the ICG stained area of the cut walls, and no heat damage was observed at the operative power levels of laser corneal welding.

Effect of Chromoendoscopy Filters on Visualization of KTP Laser-Associated Tissue Changes: A Cadaveric Animal Model.

PubMed

Johnson, Christopher M; Pate, Mariah B; Postma, Gregory N

2018-04-01

Standard KTP laser (potassium titanyl phosphate) wavelength-specific protective eyewear often impairs visualization of tissue changes during laser treatment. This sometimes necessitates eyewear removal to evaluate tissue effects, which wastes time and poses safety concerns. The objective was to determine if "virtual" or "electronic" chromoendoscopy filters, as found on some endoscopy platforms, could alleviate the restricted visualization inherent to protective eyewear. A KTP laser was applied to porcine laryngeal tissue and recorded via video laryngoscopy with 1 optical (Olympus Narrow Band Imaging) and 8 digital (Pentax Medical I-scan) chromoendoscopy filters. Videos were viewed by 11 otolaryngologists wearing protective eyewear. Using a discrete visual analog scale, they rated each filter on its ability to improve visualization,. No filter impaired visualization; 5 of 9 improved visualization. Based on statistical significance, the number of positive responses, and the lack of negative responses, narrow band imaging and the I-scan tone enhancement filter for leukoplakia performed best. These filters could shorten procedure time and improve safety; therefore, further clinical evaluation is warranted.

Laser ablation of basal cell carcinomas guided by confocal microscopy

NASA Astrophysics Data System (ADS)

Sierra, Heidy; Cordova, Miguel; Nehal, Kishwer; Rossi, Anthony; Chen, Chih-Shan Jason; Rajadhyaksha, Milind

2016-02-01

Laser ablation offers precise and fast removal of superficial and early nodular types of basal cell carcinomas (BCCs). Nevertheless, the lack of histological confirmation has been a limitation. Reflectance confocal microscopy (RCM) imaging combined with a contrast agent can offer cellular-level histology-like feedback to detect the presence (or absence) of residual BCC directly on the patient. We conducted an ex vivo bench-top study to provide a set of effective ablation parameters (fluence, number of passes) to remove superficial BCCs while also controlling thermal coagulation post-ablation to allow uptake of contrast agent. The results for an Er:YAG laser (2.9 um and pulse duration 250us) show that with 6 passes of 25 J/cm2, thermal coagulation can be effectively controlled, to allow both the uptake of acetic acid (contrast agent) and detection of residual (or absence) BCCs. Confirmation was provided with histological examination. An initial in vivo study on 35 patients shows that the uptake of contrast agent aluminum chloride) and imaging quality is similar to that observed in the ex vivo study. The detection of the presence of residual tumor or complete clearance was confirmed in 10 wounds with (additional) histology and in 25 lesions with follow-up imaging. Our results indicate that resolution is sufficient but further development and use of appropriate contrast agent are necessary to improve sensitivity and specificity. Advances in RCM technology for imaging of lateral and deep margins directly on the patient may provide less invasive, faster and less expensive image-guided approaches for treatment of BCCs.

[Grid laser photocoagulation in diffuse diabetic macular edema].

PubMed

Degenring, Robert F; Hugger, Philipp; Sauder, Gangolf; Jonas, Jost B

2004-01-01

To evaluate the clinical outcome of macular grid laser photocoagulation in the treatment of diffuse diabetic macular oedema. The retrospective study included 30 consecutive patients (41 eyes) who were treated by macular argon green grid laser photocoagulation for diffuse diabetic macular oedema. Follow-up time was 31.4 +/- 19.6 weeks. Visual acuity decreased from 0.25 +/- 0.18 (range, 0.03 - 0.8) to 0.20 +/- 0.18 (range, 0.02 - 0.8) (P = 0.045), representing a change of - 0.9 +/- 2,32 lines. 5 (12.2 %) eyes gained in visual acuity, visual acuity remained unchanged for 23 (56.1 %) eyes, and 13 (31.7 %) eyes showed a visual loss of more than one line. In eyes with a baseline visual acuity > or = 0.2 (N = 24) visual acuity dropped from 0.36 +/- 0.15 (0.2 - 0.8; median 0.3) to 0.29 +/- 0.19 (0.05 - 0.8; median 0.2) (p = 0.038). 3 eyes (12.5 %) gained > or = 2 lines, 11 eyes (45.8 %) lost > or = 2 lines, 10 eyes (41.7 %) remained stable. Mean loss was - 1.63 +/- 2.53 lines. Eyes with a baseline visual acuity < or = 0.2 did not change significantly. In the present study mean visual acuity decreased in the whole population and especially in the subgroup with a baseline visual acuity of > or = 0.2 after macular grid laser photocoagulation for diffuse diabetic macular oedema. Mean visual loss was just below the predefined 2 lines. In view of these results and upcoming new pharmacological and surgical treatment modalities, the significance of grid laser photocoagulation should be re-discussed.

SUBTHRESHOLD MICROPULSE DIODE LASER VERSUS CONVENTIONAL LASER PHOTOCOAGULATION FOR DIABETIC MACULAR EDEMA: A Meta-Analysis of Randomized Controlled Trials.

PubMed

Chen, Guohai; Tzekov, Radouil; Li, Wensheng; Jiang, Fangzheng; Mao, Sihong; Tong, Yuhua

2016-11-01

To evaluate the relative efficacy of subthreshold micropulse diode laser versus conventional laser photocoagulation for the treatment of diabetic macular edema. A comprehensive literature search was conducted to find relevant randomized controlled trials (RCTs). Efficacy estimates were determined by comparing weighted mean differences of the mean change of best-corrected visual acuity and central macular thickness from baseline. Six RCTs were selected for this meta-analysis, including 398 eyes (203 eyes in the subthreshold micropulse diode laser group and 195 eyes in the conventional laser group). Subthreshold micropulse diode laser was superior to conventional laser in terms of mean change of logMAR best-corrected visual acuity at 3, 9, and 12 months after treatment (P = 0.02; P = 0.04, and P = 0.03, respectively), and it showed a similar trend at 6 months (P = 0.05). Although, there was no significant difference in terms of mean change in central macular thickness from baseline to 3, 6, 9, or 12 months (P = 0.80; P = 0.20; P = 0.88, and P = 0.86, respectively). Subthreshold micropulse diode laser treatment resulted in better visual acuity compared with conventional laser, although the differences before 12 months are likely to be too small to be of clinical relevance and may be dependent on baseline best-corrected visual acuity. The two types of treatment seem to have similar anatomical outcome.

Investigations of initial airtightness after non-anatomic resection of lung parenchyma using a thulium-doped laser with different optical fibres.

PubMed

Kirschbaum, Andreas; Höchsmann, N; Steinfeldt, T; Seyfer, P; Pehl, A; Bartsch, D K; Palade, E

2016-08-01

Lung metastases in healthy patients should be removed non-anatomically whenever possible. This can be done with a laser. Lung parenchyma can be cut very well, because of its high energy absorption at a wavelength of 1940 nm. A coagulation layer is created on the resected surface. It is not clear, whether this surface also needs to be sutured to ensure that it remains airtight even at higher ventilation pressures. It would be helpful, if suturing could be avoided, because the lung can become too puckered, especially with multiple resections, resulting in considerable restriction. We carried out our experiments on isolated and ventilated paracardiac lung lobes of pigs. Non-anatomic resection was carried out reproducibly using three different thulium laser fibres (230, 365 and 600 μm) at two different laser power levels (10 W, 30 W) and three different resection depths (0.5, 1.0 and 2.0 cm). Initial airtightness was investigated while ventilating at normal frequency. We also investigated the bursting pressures of the resected areas by increasing the inspiratory pressure. When 230- and 365-μm fibres were used with a power of 10 W, 70 % of samples were initially airtight up to a resection depth of 1 cm. This rate fell at depths of up to 2 cm. All resected surfaces remained airtight during ventilation when 600-μm fibres were used at both laser power levels (10 and 30 W). The bursting pressures achieved with 600-μm fibres were higher than with the other fibres used: 0.5 cm, 41.6 ± 3.2 mbar; 1 cm, 38.2 ± 2.5 mbar; 2 cm, 33.7 ± 4.8 mbar. As laser power and thickness of laser fibre increased, so the coagulation zone became thicker. With a 600-μm fibre, it measured 145.0 ± 8.2 μm with 10 W power and 315.5 ± 6.4 μm with 30 W power. Closure with sutures after non-anatomic resection of lung parenchyma is not necessary when a thulium laser is used provided a 600-μm fibre and adequate laser power (30 W) are employed. At deeper resection levels, the risk of cutting small segmental bronchi is considerably increased. They must always be closed with sutures.

Flow visualization and modeling for education and outreach in low-income countries

NASA Astrophysics Data System (ADS)

Motanated, K.

2016-12-01

Being able to visualize the dynamic interaction between the movement of water and sediment flux is undeniably a profound tool for students and novices to understand complicated earth surface processes. In a laser-sheet flow visualization technique, a light source that is thin and monochromatic is required to illuminate sediments or tracers in the flow. However, an ideal laser sheet generator is rather expensive, especially for schools and universities residing in low-income countries. This project is proposing less-expensive options for a laser-sheet source and flow visualization experiment configuration for qualitative observation and quantitative analysis of the interaction between fluid media and sediments. Here, Fresnel lens is used to convert from point laser into sheet laser. Multiple combinations of laser diodes of various wavelength (nanometer) and power (milliwatt) and Fresnel lenses of various dimensions are analyzed. The pair that is able to produce the thinnest and brightest light sheet is not only effective but also affordable. The motion of sediments in a flow can be observed by illuminating the laser-sheet in an interested flow region. The particle motion is recorded by a video camera that is capable of taking multiple frames per second and having a narrow depth of view. The recorded video file can be played in a slow-motion mode so students can visually observe and qualitatively analyze the particle motion. An open source software package for Particle Imaging Velocimetry (PIV) can calculate the local velocity of particles from still images extracted from the video and create a vector map depicting particle motion. This flow visualization experiment is inexpensive and the configuration is simple to setup. Most importantly, this flow visualization technique serves as a fundamental tool for earth surface process education and can further be applied to sedimentary process modeling.

Randomized Trial Evaluating Ranibizumab Plus Prompt or Deferred Laser or Triamcinolone Plus Prompt Laser for Diabetic Macular Edema

PubMed Central

Elman, Michael J.; Aiello, Lloyd Paul; Beck, Roy W.; Bressler, Neil M.; Bressler, Susan B.; Edwards, Allison R.; Ferris, Frederick L.; Friedman, Scott M.; Glassman, Adam R.; Miller, Kellee M.; Scott, Ingrid U.; Stockdale, Cynthia R.; Sun, Jennifer K.

2010-01-01

Objective Evaluate intravitreal 0.5 mg ranibizumab or 4 mg triamcinolone combined with focal/grid laser compared with focal/grid laser alone for treatment of diabetic macular edema (DME). Design Multicenter, randomized clinical trial. Participants A total of 854 study eyes of 691 participants with visual acuity (approximate Snellen equivalent) of 20/32 to 20/320 and DME involving the fovea. Methods Eyes were randomized to sham injection + prompt laser (n=293), 0.5 mg ranibizumab + prompt laser (n=187), 0.5 mg ranibizumab + deferred (≥24 weeks) laser (n=188), or 4 mg triamcinolone + prompt laser (n=186). Retreatment followed an algorithm facilitated by a web-based, real-time data-entry system. Main Outcome Measures Best-corrected visual acuity and safety at 1 year. Results The 1-year mean change (±standard deviation) in the visual acuity letter score from baseline was significantly greater in the ranibizumab + prompt laser group (+9±11, P<0.001) and ranibizumab + deferred laser group (+9±12, P<0.001) but not in the triamcinolone + prompt laser group (+4±13, P=0.31) compared with the sham + prompt laser group (+3±13). Reduction in mean central subfield thickness in the triamcinolone + prompt laser group was similar to both ranibizumab groups and greater than in the sham + prompt laser group. In the subset of pseudophakic eyes at baseline (n=273), visual acuity improvement in the triamcinolone + prompt laser group appeared comparable to that in the ranibizumab groups. No systemic events attributable to study treatment were apparent. Three eyes (0.8%) had injection-related endophthalmitis in the ranibizumab groups, whereas elevated intraocular pressure and cataract surgery were more frequent in the triamcinolone + prompt laser group. Two-year visual acuity outcomes were similar to 1-year outcomes. Conclusions Intravitreal ranibizumab with prompt or deferred laser is more effective through at least 1 year compared with prompt laser alone for the treatment of DME involving the central macula. Ranibizumab as applied in this study, although uncommonly associated with endophthalmitis, should be considered for patients with DME and characteristics similar to those in this clinical trial. In pseudophakic eyes, intravitreal triamcinolone + prompt laser seems more effective than laser alone but frequently increases the risk of intraocular pressure elevation. PMID:20427088

Randomized trial evaluating ranibizumab plus prompt or deferred laser or triamcinolone plus prompt laser for diabetic macular edema.

PubMed

Elman, Michael J; Aiello, Lloyd Paul; Beck, Roy W; Bressler, Neil M; Bressler, Susan B; Edwards, Allison R; Ferris, Frederick L; Friedman, Scott M; Glassman, Adam R; Miller, Kellee M; Scott, Ingrid U; Stockdale, Cynthia R; Sun, Jennifer K

2010-06-01

Evaluate intravitreal 0.5 mg ranibizumab or 4 mg triamcinolone combined with focal/grid laser compared with focal/grid laser alone for treatment of diabetic macular edema (DME). Multicenter, randomized clinical trial. A total of 854 study eyes of 691 participants with visual acuity (approximate Snellen equivalent) of 20/32 to 20/320 and DME involving the fovea. Eyes were randomized to sham injection + prompt laser (n=293), 0.5 mg ranibizumab + prompt laser (n=187), 0.5 mg ranibizumab + deferred (> or =24 weeks) laser (n=188), or 4 mg triamcinolone + prompt laser (n=186). Retreatment followed an algorithm facilitated by a web-based, real-time data-entry system. Best-corrected visual acuity and safety at 1 year. The 1-year mean change (+/-standard deviation) in the visual acuity letter score from baseline was significantly greater in the ranibizumab + prompt laser group (+9+/-11, P<0.001) and ranibizumab + deferred laser group (+9+/-12, P<0.001) but not in the triamcinolone + prompt laser group (+4+/-13, P=0.31) compared with the sham + prompt laser group (+3+/-13). Reduction in mean central subfield thickness in the triamcinolone + prompt laser group was similar to both ranibizumab groups and greater than in the sham + prompt laser group. In the subset of pseudophakic eyes at baseline (n=273), visual acuity improvement in the triamcinolone + prompt laser group appeared comparable to that in the ranibizumab groups. No systemic events attributable to study treatment were apparent. Three eyes (0.8%) had injection-related endophthalmitis in the ranibizumab groups, whereas elevated intraocular pressure and cataract surgery were more frequent in the triamcinolone + prompt laser group. Two-year visual acuity outcomes were similar to 1-year outcomes. Intravitreal ranibizumab with prompt or deferred laser is more effective through at least 1 year compared with prompt laser alone for the treatment of DME involving the central macula. Ranibizumab as applied in this study, although uncommonly associated with endophthalmitis, should be considered for patients with DME and characteristics similar to those in this clinical trial. In pseudophakic eyes, intravitreal triamcinolone + prompt laser seems more effective than laser alone but frequently increases the risk of intraocular pressure elevation. Copyright 2010 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

DOE Center of Excellence in Medical Laser Applications. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jacques, S.L.

1998-01-01

An engineering network of collaborating medical laser laboratories are developing laser and optical technologies for medical diagnosis and therapy and are translating the engineering into medical centers in Portland, OR, Houston, TX, and Galveston, TX. The Center includes the University of Texas M.D. Anderson Cancer Center, the University of Texas-Austin, Texas A and M University, Rice University, the University Texas Medical Branch-Galveston, Oregon Medical Laser Center (Providence St. Vincent Medical Center, Oregon Health Sciences University, and Oregon Graduate Institute, Portland, OR), and the University of Oregon. Diagnostics include reflectance, fluorescence, Raman IR, laser photoacoustics, optical coherence tomography, and several newmore » video techniques for spectroscopy and imaging. Therapies include photocoagulation therapy, laser welding, pulsed laser ablation, and light-activated chemotherapy of cancer (photodynamic therapy, or PDT). Medical applications reaching the clinic include optical monitoring of hyperbilirubinemia in newborns, fluorescence detection of cervical dysplasia, laser thrombolysis of blood clots in heart attack and brain stroke, photothermal coagulation of benign prostate hyperplasia, and PDT for both veterinary and human cancer. New technologies include laser optoacoustic imaging of breast tumors and hemorrhage in head trauma and brain stroke, quality control monitoring of dosimetry during PDT for esophageal and lung cancer, polarization video reflectometry of skin cancer, laser welding of artificial tissue replacements, and feedback control of laser welding.« less

DOE Center of Excellence in Medical Laser Applications. Final report, December 1, 1994--November 30, 1997

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jacques, S.L.

1998-01-01

An engineering network of collaborating medical laser laboratories are developing laser and optical technologies for medical diagnosis and therapy and are translating the engineering into medical centers in Portland OR, Houston TX, and Galveston TX. The Center includes the University of Texas M.D. Anderson Cancer Center, the University of Texas-Austin, Texas A and M University, Rice University, the University Texas Medical Branch-Galveston, Oregon Medical Laser Center (Providence St. Vincent Medical Center, Oregon Health Sciences University, and Oregon Graduate Institute, Portland, OR), and the University of Oregon. Diagnostics include reflectance, fluorescence, Raman IR, laser photoacoustics, optical coherence tomography, and several newmore » video techniques for spectroscopy and imaging. Therapies include photocoagulation therapy, laser welding, pulsed laser ablation, and light-activated chemotherapy of cancer (photodynamic therapy, or PDT). Medical applications reaching the clinic include optical monitoring of hyperbilirubinemia in newborns, fluorescence detection of cervical dysplasia, laser thrombolysis of blood clots in heart attack and brain stroke, photothermal coagulant of benign prostate hyperplasia, and PDT for both veterinary and human cancer. New technologies include laser optoacoustic imaging of breast tumors and hemorrhage in head trauma and brain stroke, quality control monitoring of dosimetry during PDT for esophageal and lung cancer, polarization video reflectometry of skin cancer, laser welding of artificial tissue replacements, and feedback control of laser welding.« less

Nd:YAG and CO2 laser therapy of oral mucosal lesions.

PubMed

White, J M; Chaudhry, S I; Kudler, J J; Sekandari, N; Schoelch, M L; Silverman, S

1998-12-01

Experiences gained in the management of oral mucosal lesions by CO2 and Nd:YAG laser therapy in an outpatient clinic treated over an 80-year period are described. Lasers have indications for use in dentistry for incision, excision, and coagulation of intraoral soft tissue. Advances in laser technology have provided delivery systems for site-specific delivery of laser energy with short interaction items on tissue to be ablated. This study retrospectively evaluates a series of clinical case studies. Sixty-four patients with a variety of benign oral soft tissue lesions were treated by laser excision. Thirty-five patients were treated by a pulsed fiberoptic delivered Nd:YAG contact laser, and 29 by a continuous free-beam CO2 non-contact laser. The largest group of lesions treated were leukoplakia (39 cases). Other lesions excised and biopsied were lichen planus, squamous papilloma, pyogenic granuloma, focal melanosis, nonhealing traumatic ulceration, hemangioma, and lymphangioma. All patients were followed postoperatively (mean 6.8 months, range 1-36 months). Laser excision was well tolerated by patients with no intraoperative or postoperative adverse effects. All patients healed postsurgically with no loss of function. CO2 and Nd:YAG lasers are successful surgical options when performing excision of benign intraoral lesions. Advantages of laser therapy include minimal postoperative pain, conservative site-specific minimally invasive surgeries, and elimination of need for sutures.

The role of lasers in modern urology.

PubMed

Dołowy, Łukasz; Krajewski, Wojciech; Dembowski, Janusz; Zdrojowy, Romuald; Kołodziej, Anna

2015-01-01

The functioning of modern urological departments and the high level of service they provide is possible through, among other things, the use of modern laser techniques. Open operations have been replaced by minimally invasive procedures, and classical surgical tools by advanced lasers. The search for new applications with lasers began as technology developed. Among many devices available, holmium, diode and thulium lasers are currently the most popular. Depending on the wavelength, the absorption by water and hemoglobin and the depth of penetration, lasers can be used for coagulation, vaporization and enucleation. In many centres, after all the possibilities of pharmacological treatment have been exhausted, lasers are used as the primary treatment for patients with benign prostatic hyperplasia, with therapeutic results that are better than those obtained through open or endoscopic operations. The use of lasers in the treatment of urolithiasis, urinary strictures and bladder tumours has made treatment of older patients with multiple comorbidities safe, without further necessity to modify the anticoagulant drug treatment. Laser procedures are additionally less invasive, reduce hospitalization time and enable a shorter bladder catheterization time, sometimes even eliminating the need for bladder catherterization completely. Such procedures are also characterized by more stable outcomes and a lower number of reoperations. There are also indications that with the increased competition among laser manufacturers, decreased purchase and maintenance costs, and increased operational safety, laser equipment will become mandatory and indispensable asset in all urology wards.

Laser treatment in gynecology

NASA Astrophysics Data System (ADS)

de Riese, Cornelia

2004-07-01

This presentation is designed as a brief overview of laser use in gynecology, for non-medical researchers involved in development of new laser techniques. The literature of the past decade is reviewed. Differences in penetration, absorption, and suitable delivery media for the beams dictate clinical application. The use of CO2 laser in the treatment of uterine cervical intraepithelial lesions is well established and indications as well as techniques have not changed over 30 years. The Cochrane Systematic Review from 2000 suggests no obviously superior technique. CO2 laser ablation of the vagina is also established as a safe treatment modality for VAIN. CO2 laser permits treatment of lesions with excellent cosmetic and functional results. The treatment of heavy menstrual bleeding by destruction of the endometrial lining using various techniques has been the subject of a 2002 Cochran Database Review. Among the compared treatment modalities are newer and modified laser techniques. Conclusion by reviewers is that outcomes and complication profiles of newer techniques compare favorably with the gold standard of endometrial resection. The ELITT diode laser system is one of the new successful additions. CO2 laser is also the dominant laser type used with laparoscopy for ablation of endometriotic implants. Myoma coagulation or myolysis with Nd:Yag laser through the laparoscope or hysteroscope is a conservative treatment option. Even MRI guided percutaneous approaches have been described. No long-term data are available.

Microcautery based on zinc metallic nanoparticles photodeposited on the core of an optical fiber

NASA Astrophysics Data System (ADS)

Zaca-Morán, P.; Pastelín, C. F.; Morán, C.; Pérez-Sánchez, G. F.; Chávez, F.

2017-01-01

The experimental arrangement of a microcautery implemented by an optical fiber with zinc nanoparticles (ZnNPs) photodeposited on its core for the cauterization and coagulation in blood vessels hemostasis processes is presented. The interaction between a laser radiation source and the ZnNPS on the fiber core produces a controllable punctual heat source through the radiation intensity, which is capable of reaching a temperature up to 200 °C covering an area of approximately ten micrometers. By using three-to-four-month-old rats of CIIZ-V strain, we made several microcauterization experimental tests to stop blood flow. The findings show that the microcautery obliterates the smooth muscle of the blood vessels concatenating mutually to tissue in an average time of three seconds, at the same time, the blood elements responsible for the coagulation are thermally activated and thus the bleeding is stopped.

New 445 nm blue laser for laryngeal surgery combines photoangiolytic and cutting properties.

PubMed

Hess, Markus M; Fleischer, Susanne; Ernstberger, Marcel

2018-06-01

Photoangiolytic lasers have broadened the surgical armamentarium for many phonosurgical interventions. However, the pulse dye laser and potassium titanyl phosphate (KTP) laser have technical drawbacks and a smaller spectrum of indications. The new 445 nm wavelength laser, the so-called 'blue laser', proves to show tissue effects comparable to the KTP laser and is also capable of treating subepithelial vessels due to its photoangiolytic properties, it can coagulate and carbonize at higher energy levels, and can be used via glass fibers in non-contact and contact mode for in-office procedures. In contrast to the KTP, the new 445 nm laser can also be used as a cutting laser, thus combining very much wanted properties of diode or CO2 lasers with photoangiolytic lasers. Further advantages of the new laser are the; (1) portability of the shoe box sized, shock-proof laser machine for in-office and operating room usage, (2) the selection of pulse rates from continuous wave (cw) to less than a millisecond, (3) stronger tissue effects compared to KTP with similar energy and pulse settings, (4) far better cutting properties than the KTP, and thus (5) more possibilities for usage in laryngology as well as in other fields or surgery. We demonstrate the feasibility of the 445 nm laser in several laboratory experiments and show clinical cases where photoangiolysis and cutting was possible. However, this is a preliminary report and further systematic studies in greater numbers are warranted.

Visualization of evolving laser-generated structures by frequency domain tomography

NASA Astrophysics Data System (ADS)

Chang, Yenyu; Li, Zhengyan; Wang, Xiaoming; Zgadzaj, Rafal; Downer, Michael

2011-10-01

We introduce frequency domain tomography (FDT) for single-shot visualization of time-evolving refractive index structures (e.g. laser wakefields, nonlinear index structures) moving at light-speed. Previous researchers demonstrated single-shot frequency domain holography (FDH), in which a probe-reference pulse pair co- propagates with the laser-generated structure, to obtain snapshot-like images. However, in FDH, information about the structure's evolution is averaged. To visualize an evolving structure, we use several frequency domain streak cameras (FDSCs), in each of which a probe-reference pulse pair propagates at an angle to the propagation direction of the laser-generated structure. The combination of several FDSCs constitutes the FDT system. We will present experimental results for a 4-probe FDT system that has imaged the whole-beam self-focusing of a pump pulse propagating through glass in a single laser shot. Combining temporal and angle multiplexing methods, we successfully processed data from four probe pulses in one spectrometer in a single-shot. The output of data processing is a multi-frame movie of the self- focusing pulse. Our results promise the possibility of visualizing evolving laser wakefield structures that underlie laser-plasma accelerators used for multi-GeV electron acceleration.

Software for visualization, analysis, and manipulation of laser scan images

NASA Astrophysics Data System (ADS)

Burnsides, Dennis B.

1997-03-01

The recent introduction of laser surface scanning to scientific applications presents a challenge to computer scientists and engineers. Full utilization of this two- dimensional (2-D) and three-dimensional (3-D) data requires advances in techniques and methods for data processing and visualization. This paper explores the development of software to support the visualization, analysis and manipulation of laser scan images. Specific examples presented are from on-going efforts at the Air Force Computerized Anthropometric Research and Design (CARD) Laboratory.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogami, M; Kulkarni, R; Wang, H

We report application of laser speckle contrast imaging (LSCI), i.e., a fast imaging technique utilising backscattered light to distinguish such moving objects as red blood cells from such stationary objects as surrounding tissue, to localise skin injury. This imaging technique provides detailed information about the acute perfusion response after a blood vessel is occluded. In this study, a mouse ear model is used and pulsed laser coagulation serves as the method of occlusion. We have found that the downstream blood vessels lacked blood flow due to occlusion at the target site immediately after injury. Relative flow changes in nearby collateralsmore » and anastomotic vessels have been approximated based on differences in intensity in the nearby collaterals and anastomoses. We have also estimated the density of the affected downstream vessels. Laser speckle contrast imaging is shown to be used for highresolution and fast-speed imaging for the skin microvasculature. It also allows direct visualisation of the blood perfusion response to injury, which may provide novel insights to the field of cutaneous wound healing. (laser biophotonics)« less

Laser-supported diaphanoscopy: an innovative technique for locating gastric stromal tumors in gastroscopic-laparoscopic rendezvous: a case series.

PubMed

Patrzyk, M; Schreiber, A; Heidecke, C D; Glitsch, A

2009-12-01

Development of an innovative method of endoscopic laser-supported diaphanoscopy, for precise demonstration of the location of gastrointestinal stromal tumors (GISTs) at laparoscopy is described. The equipment consists of a light transmission cable with an anchoring system for the gastric mucosa, a connecting system for the light source, and the laser light source itself. During surgery, transillumination by laser is used to show the shape of the tumor. The resection margins are then marked by electric coagulation. Ten patients have been successfully treated using this technique in laparoscopic-endoscopic rendezvous procedures. Average time of surgery was 123 minutes. The time for marking the shape of the tumor averaged 16 minutes. Depending on tumor location and size, 4-7 marks were used, and resection margins were 4-15 mm. This new and effective technique facilitates precise locating of gastric GISTs leading to exact and tissue-sparing transmural laparoscopic resections. Georg Thieme Verlag KG Stuttgart New York.

Laser speckle imaging to improve clinical outcomes for patients with trigeminal neuralgia undergoing radiofrequency thermocoagulation.

PubMed

Ringkamp, Matthias; Wooten, Matthew; Carson, Benjamin S; Lim, Michael; Hartke, Timothy; Guarnieri, Michael

2016-02-01

Percutaneous treatments for trigeminal neuralgia are safe, simple, and effective for achieving good pain control. Procedural risks could be minimized by using noninvasive imaging techniques to improve the placement of the radiofrequency thermocoagulation probe into the trigeminal ganglion. Positioning of a probe is crucial to maximize pain relief and to minimize unwanted side effects, such as denervation in unaffected areas. This investigation examined the use of laser speckle imaging during probe placement in an animal model. This preclinical safety study used nonhuman primates, Macaca nemestrina (pigtail monkeys), to examine whether real-time imaging of blood flow in the face during the positioning of a coagulation probe could monitor the location and guide the positioning of the probe within the trigeminal ganglion. Data from 6 experiments in 3 pigtail monkeys support the hypothesis that laser imaging is safe and improves the accuracy of probe placement. Noninvasive laser speckle imaging can be performed safely in nonhuman primates. Because improved probe placement may reduce morbidity associated with percutaneous rhizotomies, efficacy trials of laser speckle imaging should be conducted in humans.

Sutureless liver repair and hemorrhage control using laser-mediated fusion of human albumin as a solder.

PubMed

Wadia, Y; Xie, H; Kajitani, M

2001-07-01

Major liver trauma has a high mortality because of immediate exsanguination and a delayed morbidity from septicemia, peritonitis, biliary fistulae, and delayed secondary hemorrhage. We evaluated laser soldering using liquid albumin for welding liver injuries. Fourteen lacerations (6 x 2 cm) and 13 nonanatomic resection injuries (raw surface, 8 x 2 cm) were repaired. An 805-nm laser was used to weld 53% liquid albumin-indocyanine green solder to the liver surface, reinforcing it by welding a free autologous omental scaffold. The animals were heparinized and hepatic inflow occlusion was used for vascular control. For both laceration and resection injuries, 16 soldering repairs were evaluated acutely at 3 hours. Eleven animals were evaluated chronically, two at 2 weeks and nine at 4 weeks. All 27 laser mediated-liver repairs had minimal blood loss compared with the suture controls. No dehiscence, hemorrhage, or bile leakage was seen in any of the laser repairs after 3 hours. All 11 chronic repairs healed without complication. This modality effectively seals the liver surface, joins lacerations with minimal thermal injury, and works independently of the patient's coagulation status.

A Pilot Study of Skin Resurfacing Using the 2,790-nm Erbium:YSGG Laser System.

PubMed

Rhie, Jong Won; Shim, Jeong Su; Choi, Won Seok

2015-01-01

The erbium:yttrium scandium gallium garnet (Er:YSGG) laser differs from other laser techniques by having a faster and higher cure rate. Since the Er:YSGG laser causes an appropriate proportion of ablation and coagulation, it has advantages over the conventional carbon dioxide (CO2) laser and the erbium-doped yttrium aluminum garnet (Er:YAG) laser, including heating tendencies and explosive vaporization. This research was conducted to explore the effects and safety of the Er:YSGG laser. Twenty patients participated in the pilot study of a resurfacing system using a 2,790-nm Er:YSGG laser. All patients received facial treatment by the 2,790-nm Er:YSGG laser system (Cutera) twice with a 4-week interval. Wrinkle reduction, reduction in pigment inhomogeneity, and improvement in tone and texture were measured. Study subjects included 15 women and five men. Re-epithelization occurred in all subjects 3 to 4 days after treatment, and wrinkle reduction, reduction in pigment inhomogeneity, and improvement in tone and texture within 6 months of treatment. The 2,790-nm YSGG laser technique had fewer complications and was effective in the improvement of scars, pores, wrinkles, and skin tone and color with one or two treatments. We expect this method to be effective for people with acne scars, pore scars, deep wrinkles, and uneven skin texture and color.

A Pilot Study of Skin Resurfacing Using the 2,790-nm Erbium:YSGG Laser System

PubMed Central

Rhie, Jong Won; Choi, Won Seok

2015-01-01

Background The erbium:yttrium scandium gallium garnet (Er:YSGG) laser differs from other laser techniques by having a faster and higher cure rate. Since the Er:YSGG laser causes an appropriate proportion of ablation and coagulation, it has advantages over the conventional carbon dioxide (CO2) laser and the erbium-doped yttrium aluminum garnet (Er:YAG) laser, including heating tendencies and explosive vaporization. This research was conducted to explore the effects and safety of the Er:YSGG laser. Methods Twenty patients participated in the pilot study of a resurfacing system using a 2,790-nm Er:YSGG laser. All patients received facial treatment by the 2,790-nm Er:YSGG laser system (Cutera) twice with a 4-week interval. Wrinkle reduction, reduction in pigment inhomogeneity, and improvement in tone and texture were measured. Results Study subjects included 15 women and five men. Re-epithelization occurred in all subjects 3 to 4 days after treatment, and wrinkle reduction, reduction in pigment inhomogeneity, and improvement in tone and texture within 6 months of treatment. Conclusions The 2,790-nm YSGG laser technique had fewer complications and was effective in the improvement of scars, pores, wrinkles, and skin tone and color with one or two treatments. We expect this method to be effective for people with acne scars, pore scars, deep wrinkles, and uneven skin texture and color. PMID:25606490

Visualization of femtosecond laser pulse-induced microincisions inside crystalline lens tissue.

PubMed

Stachs, Oliver; Schumacher, Silvia; Hovakimyan, Marine; Fromm, Michael; Heisterkamp, Alexander; Lubatschowski, Holger; Guthoff, Rudolf

2009-11-01

To evaluate a new method for visualizing femtosecond laser pulse-induced microincisions inside crystalline lens tissue. Laser Zentrum Hannover e.V., Hannover, Germany. Lenses removed from porcine eyes were modified ex vivo by femtosecond laser pulses (wavelength 1040 nm, pulse duration 306 femtoseconds, pulse energy 1.0 to 2.5 microJ, repetition rate 100 kHz) to create defined planes at which lens fibers separate. The femtosecond laser pulses were delivered by a 3-dimension (3-D) scanning unit and transmitted by focusing optics (numerical aperture 0.18) into the lens tissue. Lens fiber orientation and femtosecond laser-induced microincisions were examined using a confocal laser scanning microscope (CLSM) based on a Rostock Cornea Module attached to a Heidelberg Retina Tomograph II. Optical sections were analyzed in 3-D using Amira software (version 4.1.1). Normal lens fibers showed a parallel pattern with diameters between 3 microm and 9 microm, depending on scanning location. Microincision visualization showed different cutting effects depending on pulse energy of the femtosecond laser. The effects ranged from altered tissue-scattering properties with all fibers intact to definite fiber separation by a wide gap. Pulse energies that were too high or overlapped too tightly produced an incomplete cutting plane due to extensive microbubble generation. The 3-D CLSM method permitted visualization and analysis of femtosecond laser pulse-induced microincisions inside crystalline lens tissue. Thus, 3-D CLSM may help optimize femtosecond laser-based procedures in the treatment of presbyopia.

Telangiectatic Matting is Associated with Hypersensitivity and a Bleeding Tendency.

PubMed

Kadam, Pooja; Lim, Jerrick; Paver, Ian; Connor, David E; Parsi, Kurosh

2018-04-01

The aim was to investigate the pathogenesis of telangiectatic matting (TM) and identify possible risk factors. This study had two parts. The clinical records of consecutive patients were retrospectively analysed to identify risk factors for TM. In the second part, the haemostatic and coagulation profile of the subset of patients with TM were analysed and compared with controls using standard coagulation tests, platelet function and a global assay of coagulation (rotational thromboelastometry, ROTEM). In 352 consecutive patients presenting to a phlebology practice, 25 patients had TM (7.1%). All 25 patients were female with the median age of 45 (27-57) years. A comprehensive medical history was taken. Among 27 possible risk factors assessed, statistically significant associations included recurrent epistaxis, easy bruising, hypersensitivity (eczema, hives, hay fever, and rhinitis), previous treatment with sclerotherapy or endovenous laser for lower limb veins, and a family history of telangiectasias. Variables not associated with TM included oral contraceptive intake, hormone replacement therapy, and age. The haemostatic and coagulation profile of 12 patients (6 male and 6 female) with TM did not differ significantly from those without TM. TM is associated with both hypersensitivity and a bleeding tendency. This study revealed no significant increase in the incidence of haemostatic abnormalities in patients with TM compared with the control group. Given the significant association with hypersensitivity disorders, the underlying mast cell hyper-reactivity may contribute to both hypersensitivity and a bleeding tendency and predispose patients to TM. Copyright © 2017 European Society for Vascular Surgery. Published by Elsevier B.V. All rights reserved.

Argon Plasma Coagulation Therapy Versus Topical Formalin for Intractable Rectal Bleeding and Anorectal Dysfunction After Radiation Therapy for Prostate Carcinoma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yeoh, Eric, E-mail: eric.yeoh@health.sa.gov.au; School of Medicine, University of Adelaide, Adelaide; Tam, William

Purpose: To evaluate and compare the effect of argon plasma coagulation (APC) and topical formalin for intractable rectal bleeding and anorectal dysfunction associated with chronic radiation proctitis. Methods and Materials: Thirty men (median age, 72 years; range, 49-87 years) with intractable rectal bleeding (defined as ≥1× per week and/or requiring blood transfusions) after radiation therapy for prostate carcinoma were randomized to treatment with APC (n=17) or topical formalin (n=13). Each patient underwent evaluations of (1) anorectal symptoms (validated questionnaires, including modified Late Effects in Normal Tissues–Subjective, Objective, Management, and Analytic and visual analogue scales for rectal bleeding); (2) anorectal motormore » and sensory function (manometry and graded rectal balloon distension); and (3) anal sphincteric morphology (endoanal ultrasound) before and after the treatment endpoint (defined as reduction in rectal bleeding to 1× per month or better, reduction in visual analogue scales to ≤25 mm, and no longer needing blood transfusions). Results: The treatment endpoint was achieved in 94% of the APC group and 100% of the topical formalin group after a median (range) of 2 (1-5) sessions of either treatment. After a follow-up duration of 111 (29-170) months, only 1 patient in each group needed further treatment. Reductions in rectal compliance and volumes of sensory perception occurred after APC, but no effect on anorectal symptoms other than rectal bleeding was observed. There were no differences between APC and topical formalin for anorectal symptoms and function, nor for anal sphincteric morphology. Conclusions: Argon plasma coagulation and topical formalin had comparable efficacy in the durable control of rectal bleeding associated with chronic radiation proctitis but had no beneficial effect on anorectal dysfunction.« less

Confluent diode laser coagulation: the gold standard of therapy for retinopathy of prematurity.

PubMed

Prepiaková, Zuzana; Tomcíková, Dana; Kostolná, Barbora; Gerinec, Anton

2015-01-01

The authors compare results of retinopathy of prematurity treatment with single-spot diode laser coagulation (DLC) versus confluent DLC. The final anatomical outcome and need for additional therapy, such as additional DLC, cryotherapy, scleral buckling, and intravitreal bevacizumab, were evaluated. A retrospective review of patients with threshold retinopathy of prematurity treated between January 2001 and October 2012 was conducted. Single-spot laser treatment or confluent laser treatment was applied anterior to the ridge extending to the ora serrata. In the first group (the single-spot group), a single-spot DLC was used between January 2001 and May 2008. The single-spot group included 338 patients (671 eyes) with retinopathy of prematurity. In the second group (the confluent group), confluent DLC was used in 326 patients (652 eyes) between June 2008 and October 2012. The authors compared the need for re-treatment to achieve regression of retinopathy of prematurity in both groups. The rate of progression, frequency of re-treatment, complications, and structural outcomes were evaluated. In the single-spot group, re-treatment only with DLC was necessary in 43 (6.4%) eyes, additional cryotherapy was performed in 22 (3.3%) eyes, and scleral buckling in 107 (15.9%) eyes. Altogether, additional therapy was used in 172 (25.6%) eyes. In the confluent group, re-treatment with DLC was used in 5 (0.8%) eyes, additional cryotherapy in 6 (0.9%) eyes, scleral buckling in 16 (2.5%) eyes, and intravitreal bevacizumab in 14 (2.1%) eyes. Altogether, additional therapy was used in 41 (6.3%) eyes. The confluent group showed a favorable anatomical outcome in 99.1% of the cases compared with 96.4% in the single-spot group. The results were statistically significant (P = .001.) The DLC method was significantly more effective than single-spot DLC in the treatment of retinopathy of prematurity. Copyright 2015, SLACK Incorporated.

Changes in vision related quality of life in patients with diabetic macular edema: ranibizumab or laser treatment?

PubMed

Turkoglu, Elif Betul; Celık, Erkan; Aksoy, Nilgun; Bursalı, Ozlem; Ucak, Turgay; Alagoz, Gursoy

2015-01-01

To compare the changes in vision related quality of life (VR-QoL) in patients with diabetic macular edema (DME) undergoing intravitreal ranibizumab (IVR) injection or focal/grid laser. In this prospective study, 70 patients with clinically significant macular edema (CSME) were randomized to undergo IVR injection (n=35) and focal/grid laser (n=35). If necessary, the laser or ranibizumab injections were repeated. Distance and near visual acuities, central retinal thickness (CRT) and The 25-item Visual Function Questionnaire (VFQ-25) were used to measure the effectiveness of treatments and VR-QoL before and after 6 months following IVR or laser treatment. The demographic and clinical findings before the treatments were similar in both main groups. The improvements in distance and near visual acuities were higher in IVR group than the laser group (p<0.01). The reduction in CRT in IVR group was higher than that in laser treatment group (p<0.01). In both groups, the VFQ-25 composite score tended to improve from baseline to 6 months. And at 6th month, the changes in composite score were significantly higher in IVR group than in laser group (p<0.05). The improvements in overall composite scores were 6.3 points for the IVR group compared with 3.0 points in the laser group. Patients treated with IVR and laser had large improvements in composite scores, general vision, near and distance visual acuities in VFQ-25 at 6 months, in comparison with baseline scores, and also mental health subscale in IVR group. Our study revealed that IVR improved not only visual acuity or CRT, but also vision related quality of life more than laser treatment in DME. And these patient-reported outcomes may play an important role in the treatment choice in DME for clinicians. Copyright © 2015 Elsevier Inc. All rights reserved.

[An experimental study of the coagulating properties of a laser beam applied to fix titanium prostheses of auditory ossicles with the use of platelet-rich plasma].

PubMed

Semenov, V F; Semenov, F V

2013-01-01

The displacement of prostheses of auditory ossicles at the concluding stage of surgery and in the early postoperative period is one of the factors influencing the functional outcome of stapedoplasty. The objective of the present experimental study was to estimate the effectiveness of the use of platelet-rich plasma as an alloy for the laser welding in order to improve fixation of titanium prostheses employed in ossiculoplastic surgery. The results of a series of experiments undertaken to assess the possibility of stabilization of titanium prostheses in the desired position with the help of laser welding indicate that this technique with the use of platelet-rich plasma as an alloy may be a reliable method for the fixation of the reconstructed chain of ossicles in the desired position.

The KTP-(greenlight-) laser--principles and experiences.

PubMed

Bachmann, Alexander; Ruszat, Robin

2007-01-01

The most recent advance in laser technology for transurethral prostatectomy is represented by the KTP laser. A potassium-titanyl-phosphate-(KTP-) crystal doubles the frequency of pulsed Neodymium: Yttrium-Aluminum-Garnet (Nd:YAG) laser energy to a 532 nm wavelength, which is in the green electromagnetic spectrum (Greenlight-laser) and is selectively absorbed by hemoglobin and not at all by water. Reducing the wavelength leads to a completely different interaction between laser beam and prostatic tissue. In contrast to the early clinical experiences with the Nd:YAG lasers in which vaporization was observed as a side-effect during the procedure, the new KTP laser offers an immediate and efficient vaporization, leading to real tissue ablation. Because of the instant and nearly complete absorption in blood, the depth in vascularized tissue such as prostate is only 0.8 mm. The superficial coagulation prevents the large tissue necrosis that is seen with the Nd:YAG laser, leading to long lasting irritative symptoms due to sloughing of necrotic tissue. Initial experiences, made with a 60W KTP system, demonstrated that the procedure was as effective as conventional transurethral resection of the prostate (TURP) with a lower intraoperative complication rate. In order to speed up vaporization of the prostate laser power has been increased to 80W. The 80W KTP laser combines the tissue debulking properties of TURP and the favourable safety profile of laser surgery. With the new 120W High Performance System, introduced in 2006, vaporization will become more powerful and faster. Initial reports are awaited.

Navigated macular laser decreases retreatment rate for diabetic macular edema: a comparison with conventional macular laser.

PubMed

Neubauer, Aljoscha S; Langer, Julian; Liegl, Raffael; Haritoglou, Christos; Wolf, Armin; Kozak, Igor; Seidensticker, Florian; Ulbig, Michael; Freeman, William R; Kampik, Anselm; Kernt, Marcus

2013-01-01

The purpose of this study was to evaluate and compare clinical outcomes and retreatment rates using navigated macular laser versus conventional laser for the treatment of diabetic macular edema (DME). In this prospective, interventional pilot study, 46 eyes from 46 consecutive patients with DME were allocated to receive macular laser photocoagulation using navigated laser. Best corrected visual acuity and retreatment rate were evaluated for up to 12 months after treatment. The control group was drawn based on chart review of 119 patients treated by conventional laser at the same institutions during the same time period. Propensity score matching was performed with Stata, based on the nearest-neighbor method. Propensity score matching for age, gender, baseline visual acuity, and number of laser spots yielded 28 matched patients for the control group. Visual acuity after navigated macular laser improved from a mean 0.48 ± 0.37 logMAR by a mean +2.9 letters after 3 months, while the control group showed a mean -4.0 letters (P = 0.03). After 6 months, navigated laser maintained a mean visual gain of +3.3 letters, and the conventional laser group showed a slower mean increase to +1.9 letters versus baseline. Using Kaplan-Meier analysis, the laser retreatment rate showed separation of the survival curves after 2 months, with fewer retreatments in the navigated group than in the conventional laser group during the first 8 months (18% versus 31%, respectively, P = 0.02). The short-term results of this pilot study suggest that navigated macular photocoagulation is an effective technique and could be considered as a valid alternative to conventional slit-lamp laser for DME when focal laser photocoagulation is indicated. The observed lower retreatment rates with navigated retinal laser therapy in the first 8 months suggest a more durable treatment effect.

Lentivirus-mediated RNA interference of vascular endothelial growth factor in monkey eyes with iris neovascularization.

PubMed

Yuan, Meng-Ke; Tao, Yong; Yu, Wen-Zhen; Kai, Wang; Jiang, Yan-Rong

2010-08-25

To explore the in vivo anti-angiogenesis effects resulting from lentivirus-mediated RNAi of vascular endothelial growth factor (VEGF) in monkeys with iris neovascularization (INV). Five specific recombinant lentiviral vectors for RNA interference, targeting Macaca mulatta VEGFA, were designed and the one with best knock down efficacy (LV-GFP-VEGFi1) in H1299 cells and RF/6A cells was selected by real-time PCR for in vivo use. A laser-induced retinal vein occlusion model was established in one eye of seven cynomolgus monkeys. In monkeys number 1, 3, and 5 (Group 1), the virus (1x10(8) particles) was intravitreally injected into the preretinal space of the animal's eye immediately after laser coagulation; and in monkeys number 2, 4, and 6 (Group 2), the virus (1x10(8) particles) was injected at 10 days after laser coagulation. In monkey number 7, a blank control injection was performed. In monkeys number 1 and 2, virus without RNAi sequence was used; in monkeys number 3 and 4, virus with nonspecific RNAi sequence was used; and in monkeys 5 and 6, LV-GFP-VEGFi1 was used. In monkey number 5, at 23 days after laser treatment, no obvious INV was observed, while fluorescein angiography of the iris revealed high fluorescence at the margin of pupil and point posterior synechiae. At 50 days after laser treatment, only a slight ectropion uvea was found. However, in the other eyes, obvious INV or hyphema was observed. The densities of new iridic vessels all significantly varied: between monkey number 5 and number 3 (36.01+/-4.49/mm(2) versus 48.68+/-9.30/mm(2), p=0.025), between monkey number 3 and monkey number 7 (48.68+/-9.30/mm(2) versus 74.38+/-9.23/mm(2), p=0.002), and between monkey number 5 and number 7 (36.01+/-4.49/mm(2) versus 74.38+/-9.23/mm(2), p<0.001). Lentivirus-mediated RNAi of VEGF may be a new strategy to treat iris neovascularization, while further studies are needed to investigate the long-term effect.

Clinical Outcomes of an Optimized Prolate Ablation Procedure for Correcting Residual Refractive Errors Following Laser Surgery.

PubMed

Chung, Byunghoon; Lee, Hun; Choi, Bong Joon; Seo, Kyung Ryul; Kim, Eung Kwon; Kim, Dae Yune; Kim, Tae-Im

2017-02-01

The purpose of this study was to investigate the clinical efficacy of an optimized prolate ablation procedure for correcting residual refractive errors following laser surgery. We analyzed 24 eyes of 15 patients who underwent an optimized prolate ablation procedure for the correction of residual refractive errors following laser in situ keratomileusis, laser-assisted subepithelial keratectomy, or photorefractive keratectomy surgeries. Preoperative ophthalmic examinations were performed, and uncorrected distance visual acuity, corrected distance visual acuity, manifest refraction values (sphere, cylinder, and spherical equivalent), point spread function, modulation transfer function, corneal asphericity (Q value), ocular aberrations, and corneal haze measurements were obtained postoperatively at 1, 3, and 6 months. Uncorrected distance visual acuity improved and refractive errors decreased significantly at 1, 3, and 6 months postoperatively. Total coma aberration increased at 3 and 6 months postoperatively, while changes in all other aberrations were not statistically significant. Similarly, no significant changes in point spread function were detected, but modulation transfer function increased significantly at the postoperative time points measured. The optimized prolate ablation procedure was effective in terms of improving visual acuity and objective visual performance for the correction of persistent refractive errors following laser surgery.

Effect of solvent evaporation and coagulation on morphology development of asymmetric membranes

NASA Astrophysics Data System (ADS)

Chandrasekaran, Neelakandan; Kyu, Thein

2008-03-01

Miscibility behavior of blends of amorphous polyamide (PA) and polyvinylpyrrolidone (PVP) was studied in relation to membrane formation. Dimethylsulfoxide (DMSO) and water were used as solvent and non-solvent, respectively. Differential scanning calorimetry and cloud point measurements revealed that the binary PA/PVP blends as well as the ternary PA/PVP/DMSO system were completely miscible at all compositions. However, the addition of non-solvent (water) to this ternary system has led to phase separation. Visual turbidity study was used to establish a ternary liquid-liquid phase diagram of the PA-PVP/DMSO/water system. Scanning Electron Microscopy (SEM) showed the development of finger-like and sponge-like cross sectional morphologies during coagulation. Effects of polymer concentration, PA/PVP blend ratio, solvent/non-solvent quality, and evaporation time on the resulting membrane morphology will be discussed.

Tm:fiber laser ablation with real-time temperature monitoring for minimizing collateral thermal damage: ex vivo dosimetry for ovine brain.

PubMed

Tunc, Burcu; Gulsoy, Murat

2013-01-01

The thermal damage of the surrounding tissue can be an unwanted result of continuous-wave laser irradiations. In order to propose an effective alternative to conventional surgical techniques, photothermal damage must be taken under control by a detailed dose study. Real-time temperature monitoring can be also an effective way to get rid of these negative effects. The aim of the present study is to investigate the potential of a new laser-thermoprobe, which consists of a continuous-wave 1,940-nm Tm:fiber laser and a thermocouple measurement system for brain surgery in an ex vivo study. A laser-thermoprobe was designed for using the near-by tissue temperature as a real-time reference for the applicator. Fresh lamb brain tissues were used for experiments. 320 laser shots were performed on both cortical and subcortical tissue. The relationship between laser parameters, temperature changes, and ablation (removal of tissue) efficiency was determined. The correlation between rate of temperature change and ablation efficiency was calculated. Laser-thermoprobe leads us to understand the basic laser-tissue interaction mechanism in a very cheap and easy way, without making a change in the experimental design. It was also shown that the ablation and coagulation (thermally irreversible damage) diameters could be predicted, and carbonization can be avoided by temperature monitoring. Copyright © 2013 Wiley Periodicals, Inc.

Small-spot laser-exposure effects on visual function

NASA Astrophysics Data System (ADS)

Zwick, Harry; Robbins, David O.; Stuck, Bruce E.; Lund, David J.; Reynolds, Scottie B.; Nawim, Maqsood; Schuschereba, Steven T.

1990-07-01

Laser field exposure effects on visual function involve produc tJon of minimal spot irradiation on or near the huntan fovea. Functional effects of such exposure may involve transient or perinanent change in visual function depending upon exposure dose. While Maximun Permissible Exposure (MPE) lirrtits define exposure in terins of threshold retinal niorphological change such limits are not applicable with regard to transient changes in visual function below MPE limits induced by alteration in retinal physiological processes. Mechanisms of transient and permanent functional change reported in these exper iments point out the need to examine laser safety limits in terms of both the functional as well as the morphological disturbance induced in retinal tissue. L

Vascular anomalies: classification, imaging characteristics and implications for interventional radiology treatment approaches

PubMed Central

Prajapati, H J S; Martin, L G; Patel, T H

2014-01-01

The term vascular anomaly represents a broad spectrum of vascular pathology, including proliferating vascular tumours and vascular malformations. While the treatment of most vascular anomalies is multifactorial, interventional radiology procedures, including embolic therapy, sclerotherapy and laser coagulation among others, are playing an increasingly important role in vascular anomaly management. This review discusses the diagnosis and treatment of common vascular malformations, with emphasis on the technique, efficacy and complications of different interventional radiology procedures. PMID:24588666

The role of lasers in modern urology

PubMed Central

Dołowy, Łukasz; Dembowski, Janusz; Zdrojowy, Romuald; Kołodziej, Anna

2015-01-01

Introduction The functioning of modern urological departments and the high level of service they provide is possible through, among other things, the use of modern laser techniques. Material and methods Open operations have been replaced by minimally invasive procedures, and classical surgical tools by advanced lasers. The search for new applications with lasers began as technology developed. Among many devices available, holmium, diode and thulium lasers are currently the most popular. Results Depending on the wavelength, the absorption by water and hemoglobin and the depth of penetration, lasers can be used for coagulation, vaporization and enucleation. In many centres, after all the possibilities of pharmacological treatment have been exhausted, lasers are used as the primary treatment for patients with benign prostatic hyperplasia, with therapeutic results that are better than those obtained through open or endoscopic operations. The use of lasers in the treatment of urolithiasis, urinary strictures and bladder tumours has made treatment of older patients with multiple comorbidities safe, without further necessity to modify the anticoagulant drug treatment. Laser procedures are additionally less invasive, reduce hospitalization time and enable a shorter bladder catheterization time, sometimes even eliminating the need for bladder catherterization completely. Such procedures are also characterized by more stable outcomes and a lower number of reoperations. Conclusions There are also indications that with the increased competition among laser manufacturers, decreased purchase and maintenance costs, and increased operational safety, laser equipment will become mandatory and indispensable asset in all urology wards. PMID:26251737

Experimental comparative study on morphological effects of different lasers on the liver.

PubMed

Godlewski, G; Miro, L; Chevalier, J M; Bureau, J P

1982-01-01

Three types of laser radiation were compared as to their capabilities in hepatic surgery using 17 New Zealand rabbits. In four animals, subtotal scalpel lobectomy was performed, the hepatic pedicle being clamped. Hemostasis is obtained by means of argon or Nd YAG laser as long as the internal diameter of the vessels encountered is less than 4.5 mm. Nd YAG laser requires a power output four times higher than argon laser to obtain hemostasis. In six animals limited resection was performed by means of Nd YAG and CO2 lasers. CO2 radiation supplied insufficient hemostasis whenever the vessel diameter was more than 1 mm despite an excellent cutting power. Nd YAG radiation created an important necrosis zone due to thermal diffusion. In seven animals various focal hepatic lesions produced by the three types of laser were compared. Argon laser induced superficial and regularly round lesion, Nd YAG laser deeper, cauliflower-like lesions with thermal diffusion following especially vessels. Veins presented thrombosis of their blood content and coagulation necrosis of their wall. The amount of glycogenic granulation decreased. The CO2 laser induced very sharp punctual lesion without necrosis. Electron-microscopic sections revealed faint shadowy liver cells closet to the thermal source and bubbled mitochondria containing disrupted critea around the lesion. In later lesions Nd YAG laser produced more extensive fibrosis than argon or CO2 laser. After first clinical trials we believe that laser irradiation is actually an adjuvant safety factor in current hepatic surgery, whereas the Nd YAG laser could be of real interest in metastatic carcinoma destruction in liver.

Effect of varying chromophores used in light-activated protein solders on tensile strength and thermal damage profile of repairs.

PubMed

Hoffman, Grant T; Byrd, Brian D; Soller, Eric C; Heintzelman, Douglas L; McNally-Heintzelman, Karen M

2003-01-01

Clinical adoption of laser tissue welding (LTW) techniques has been beleaguered by problems associated with thermal damage of tissue and insufficient strength of the resulting tissue bond. The magnitude of these problems has been significantly reduced with the incorporation of indocyanine green (ICG)-doped protein solders into the LTW procedure to form a new technique known as laser tissue soldering (LTS). With the addition of ICG, a secondary concern has arisen relating to the potential harmful effects of the degradation products of the chromophore upon thermal denaturation of the protein solder with a laser. In this study, two different food colorings were investigated, including blue #1 and green consisting of yellow #5 and blue #1, as alternative chromophores for use in LTS techniques. Food coloring has been found to have a suitable stability and safety profile for enteral use when heated to temperatures above 200 degrees C; thus, it is a promising candidate chromophore for LTS which typically requires temperatures between 50 degrees C and 100 degrees C. Experimental investigations were conducted to test the tensile strength of ex vivo repairs formed using solders doped with these alternative chromophores in a bovine model. Two commonly used chromophores, ICG and methylene blue (MB), were investigated as a reference. In addition, the temperature rise, depth of thermal coagulation in the protein solder, and the extent of thermal damage in the surrounding tissue were measured. Temperature rise at the solder/tissue interface, and consequently the degree of solder coagulation and collateral tissue thermal damage, was directly related to the penetration depth of laser light in the protein solder. Variation of the chromophore concentration such that the laser light penetrated to a depth approximately equal to half the thickness of the solder resulted in uniform results between each group of chromophores investigated. Optimal tensile strength of repairs was achieved by optimizing laser and solder parameters to obtain a temperature of approximately 65 degrees C at the solder/tissue interface. The two alternative chromophores tested in this study show considerable promise for application in LTS techniques, with equivalent tensile strength to solders doped with ICG or MB, and the potential advantage of eliminating the risks associated with harmful byproducts.

Comparison of laser- and RF-based interstitial coagulation systems for the treatment of liver tumors (Invited Paper)

NASA Astrophysics Data System (ADS)

de Jager, Arjan A.; van Trier, Bart N.; Veenendaal, Liesbeth M.; van Hillegersberg, Richard; Verdaasdonk, Rudolf M.

2005-04-01

Hepatocellular carcinoma (HCC) is one of the most common cancers in the world. Surgical treatments, including hepatic resection and liver transplantation are considered as the most effective treatment of HCC. However, less than 20% of HCC patients can be treated surgically because of: multi-focal diseases, proximity of tumor to key vascular or biliary structures and inadequate functional hepatic reserve related coexistent cirrhosis. In this unfortunate groups of patients various palliative treatments modalities are being performed to extend the time of survival and quality of life. These techniques include trans-catheter arterial chemoembolization (TACE), percutaneous ethanol injection (PEI) and Interstitial Thermal Therapy: laser-induced interstitial thermotherapy (LITT) and radio-frequency ablation (RFA).

Comparison of DLK incidence after laser in situ keratomileusis associated with two femtosecond lasers: Femto LDV and IntraLase FS60

PubMed Central

Tomita, Minoru; Sotoyama, Yuko; Yukawa, Satoshi; Nakamura, Tadayuki

2013-01-01

Purpose To compare the incidence of diffuse lamellar keratitis (DLK) after laser in situ keratomileusis (LASIK) with flap creation using the Femto LDV and IntraLase™ FS60 femtosecond lasers.0 Methods A total of 818 consecutive myopic eyes had LASIK performed using either Femto LDV or IntraLase FS60 for flap creation. The same excimer laser, the Allegretto Wave® Eye-Q Laser, was used for correcting refractive errors for all patients. In the preoperative examination, uncorrected distance visual acuity, corrected distance visual acuity, and manifest refraction spherical equivalent were measured. At the postop examination, the same examinations were performed along with a slit-lamp biomicroscopic examination, and patients with DLK were classified into stages. For the statistical analysis of the DLK occurrence rate and the visual and refractive outcomes, the Mann-Whitney’s U-test was used. Results In the Femto LDV group with 514 eyes, 42 (8.17%) had DLK. In the IntraLase FS60 group with 304 eyes, 114 (37.5%) had DLK. There was a statistically significant difference in the DLK incidence rate between these groups (P < 0.0001). Both groups had excellent visual and refractive outcomes. Although low levels of DLK were observed for both groups, they did not affect visual acuity. Conclusion While there were significantly fewer incidences of low level DLK when using Femto LDV, neither femtosecond laser induced high levels of DLK, and any postoperative DLK cleared up within 1 week. Therefore, both lasers provide excellent results, with no clinical differences, and both excel at flap creation for LASIK. PMID:23874077

Application of a laser scanner to three dimensional visual sensing tasks

NASA Technical Reports Server (NTRS)

Ryan, Arthur M.

1992-01-01

The issues are described which are associated with using a laser scanner for visual sensing and the methods developed by the author to address them. A laser scanner is a device that controls the direction of a laser beam by deflecting it through a pair of orthogonal mirrors, the orientations of which are specified by a computer. If a calibrated laser scanner is combined with a calibrated camera, it is possible to perform three dimensional sensing by directing the laser at objects within the field of view of the camera. There are several issues associated with using a laser scanner for three dimensional visual sensing that must be addressed in order to use the laser scanner effectively. First, methods are needed to calibrate the laser scanner and estimate three dimensional points. Second, methods to estimate three dimensional points using a calibrated camera and laser scanner are required. Third, methods are required for locating the laser spot in a cluttered image. Fourth, mathematical models that predict the laser scanner's performance and provide structure for three dimensional data points are necessary. Several methods were developed to address each of these and has evaluated them to determine how and when they should be applied. The theoretical development, implementation, and results when used in a dual arm eighteen degree of freedom robotic system for space assembly is described.

Use of the holmium:YAG laser in urology.

PubMed

Johnson, D E; Cromeens, D M; Price, R E

1992-01-01

The tissue effects of a holmium:YAG (Ho:YAG) laser operating at a wavelength of 2.1 mu with a maximum power of 15 watts (W) and 10 different energy-pulse settings was systematically evaluated on kidney, bladder, prostate, ureteral, and vasal tissue in the dog. In addition, various urologic surgical procedures (partial nephrectomy, transurethral laser incision of the prostate, and laser-assisted vasovasostomy) were performed in the dog, and a laparoscopic pelvic lymph node dissection was carried out in a pig. Although the Ho:YAG laser has a strong affinity for water, precise tissue ablation was achieved in both the contact and non-contact mode when used endoscopically in a fluid medium to ablate prostatic and vesical tissue. Using the usual parameters for tissue destruction (blanching without charring), the depth of thermal injury in the bladder and ureter was kept superficial. In performing partial nephrectomies, a 2-fold reduction in the zone of coagulative necrosis was demonstrated compared to the use of the continuous wave Neodymium:YAG laser (Nd:YAG). When used through the laparoscope, the Ho:YAG laser provided precise cutting and, combined with electrocautery, allowed the dissection to proceed quickly and smoothly. Hemostatic control was adequate in all surgical procedures. Although the results of these investigations are preliminary, our initial experience with the Ho:YAG laser has been favorable and warrants further investigations.

Mucosa-sparing, KTP laser coagulation of submucosal telangiectatic vessels in patients with radiation-induced cystitis: a novel approach.

PubMed

Talab, Saman Shafaat; McDougal, W Scott; Wu, Chin-Lee; Tabatabaei, Shahin

2014-08-01

This study aimed evaluate the safety and feasibility of endoscopic potassium titanyl phosphate (KTP) laser application in the management of patients with radiation-induced hemorrhagic cystitis (RHC). We retrospectively reviewed the records of 20 patients with RHC who underwent endoscopic KTP laser ablation of telangiectatic bladder vessels between October 2005 and January 2013. After initial cystoscopy, KTP laser was used to ablate the submucosal vasculature while preserving the overlying mucosa. The surgical outcome was evaluated by duration of hematuria-free interval, number of episodes of hematuria, and number of required medical and/or surgical interventions after initial treatment. Overall, 20 patients underwent 26 sessions of KTP laser ablation of bladder vessels. The procedure was able to stop bleeding 92% of the time and the average hematuria-free interval after ablation was 11.8 months, with a range of 1-37 months. In 13 patients (65%) hematuria resolved after 1 session of KTP laser treatment, whereas 5 patients (25%) required multiple sessions. Two patients (10%) with severe hematuria continued to have bleeding after laser treatment, which necessitated proximal diversion of urine with percutaneous nephrostomy tubes to control bleeding. This study suggests that KTP laser, with its unique photoselectivity property, is a safe, effective, and durable treatment with minimal side effects for ablation of submucosal bladder vessels in patients with RHC. Copyright © 2014 Elsevier Inc. All rights reserved.

Limited lung resection using the potassium-titanyl-phosphate laser.

PubMed

Nagayasu, Takeshi; Matsumoto, Keitaro; Morino, Shigeyuki; Tagawa, Tsutomu; Nakamura, Akihiro; Abo, Takafumi; Yamasaki, Naoya; Hayashi, Tomayoshi

2006-04-01

Recently, the use of the potassium-titanyl-phosphate (KTP) laser with a wavelength of 532 nm, which is half the wavelength of the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser, has been expanding in many fields, since this laser offers hemostasis and vaporization with minimal coagulation of the underlying structures. The purpose of this study was to determine the usefulness of the KTP laser in limited lung resection done for pulmonary nodular lesions. We used the KTP laser to manage 10 partial resections (Group 1) and 16 segmentectomies (Group 2). The variables that were used to compare the two methods of resection included intra-operative blood loss, mean drainage time, and post-operative morbidity. The mean intra-operative blood loss was smaller in Group 1 (152.8 +/- 65.0 cc, P = 0.002) than in Group 2 (341.9 +/- 178.6 cc). Mean drainage time was shorter in Group 1 (1.8 +/- 1.0 days, P = 0.0141) than in Group 2 (3.6 +/- 2.9 days). The results of both groups with respect to hemostatic and healing effects were satisfactory. On histopathologic evaluation, the KTP laser-irradiated field tissue alteration consisted of two layers with a depth up to 2 mm. The results of this study suggest that the KTP laser has the potential to become a useful and reliable tool for limited lung resection. Copyright 2006 Wiley-Liss, Inc.

Flexible omnidirectional carbon dioxide laser as an effective tool for resection of brainstem, supratentorial, and intramedullary cavernous malformations.

PubMed

Choudhri, Omar; Karamchandani, Jason; Gooderham, Peter; Steinberg, Gary K

2014-03-01

Lasers have a long history in neurosurgery, yet bulky designs and difficult ergonomics limit their use. With its ease of manipulation and multiple applications, the OmniGuide CO2 laser has reintroduced laser technology to the microsurgical resection of brain and spine lesions. This laser, delivered through a hollow-core fiber lined with a unidirectional mirror, minimizes energy loss and allows precise targeting. To analyze resections performed by the senior author from April 2009 to March 2013 of 58 cavernous malformations (CMs) in the brain and spine with the use of the OmniGuide CO2 laser, to reflect on lessons learned from laser use in eloquent areas, and to share data on comparisons of laser power calibration and histopathology. Data were collected from electronic medical records, radiology reports, operative room records, OmniGuide CO2 laser case logs, and pathology records. Of 58 CMs, approximately 50% were in the brainstem (30) and the rest were in supratentorial (26) and intramedullary spinal locations (2). Fifty-seven, ranging from 5 to 45 mm, were resected, with a subtotal resection in 1. Laser power ranged from 2 to 10 W. Pathology specimens showed minimal thermal damage compared with traditionally resected specimens with bipolar coagulation. The OmniGuide CO2 laser is safe and has excellent precision for the resection of supratentorial, brainstem, and spinal intramedullary CMs. No laser-associated complications occurred, and very low energy was used to dissect malformations from their surrounding hemosiderin-stained parenchymas. The authors recommend its use for deep-seated and critically located CMs, along with traditional tools.

Cleveland Clinic experience with interstitial laser coagulation of the prostate

NASA Astrophysics Data System (ADS)

Ulchaker, James C.; Ng, Christopher S.; Palone, David; Angie, Michelle; Kursh, Elroy D.

2000-05-01

Transurethral resection of the prostate (TURP) has long been considered the gold standard therapy for benign prostatic hyperplasia (BPH). The problems associated with the TURP, which have been extensively described, include significant bleeding, TUR syndrome, incontinence, stricture, bladder neck contracture, and sexual dysfunction. The desire for simpler, less morbid alternative therapies to TURP has led to an eruption of research and development in the last decade. This is fueled by the continued research for more economical alternatives in our current high cost health care system.

Device for fluorescent control and photodynamic therapy of age-related macula degeneration

NASA Astrophysics Data System (ADS)

Loschenov, Victor B.; Meerovich, Gennadii A.; Budzinskaya, M. V.; Ermakova, N. A.; Shevchik, S. A.; Kharnas, Sergey S.

2004-07-01

Age-related macula degeneration (AMD) is a wide spread disease the appearance of which leads to poor eyesight and blindness. A method of treatment is not determined until today. Traditional methods, such as laser coagulation and surgical operations are rather traumatic for eye and often bring to complications. That's why recently a photodynamic method of AMD treatment is studied. Based on photodynamic occlusion of choroidal neovascularization (CNV) with minimal injury to overlying neurosensory retina what increases the efficiency.

International Laser Radar Conference (16th) held at the Massachusetts Institute of Technology, Cambridge, Massachusetts on 20-24 July 1992. Part 1

DTIC Science & Technology

1993-07-24

orders smaller than the Rayleigh cross section. We estimated the extinction coefficients of the Pinatubo volcanic aerosol in the stratosphere using a Raman...to a common aerosol parameter (e.g., backscatter coefficients at selected CO2 wavelengths), have all led to similar estimated values of that...increase only as -r 2 . During this phase, therefore, the backscatter coefficient of a coagulating aerosol population decreases as -r- The maximum

Propionyl-L-carnitine improves endothelial function, microcirculation and pain management in critical limb ischemia.

PubMed

De Marchi, S; Zecchetto, S; Rigoni, A; Prior, M; Fondrieschi, L; Scuro, A; Rulfo, F; Arosio, E

2012-10-01

Chronic critical limb ischemia (CLI) is a severe condition of hypo-perfusion of lower limbs, which is associated with inflammation and a pro-coagulative state. It is a disease at high risk of amputation and cardiovascular death. Propionyl-L-carnitine (PLC) is efficacious in improving pain free walking distance in peripheral arterial disease with claudication; it also exerts favorable effects on the arterial wall and on endothelial function. The purpose of this study was to evaluate the effects of PLC on microcirculation, endothelial function and pain relief in patients affected by CLI not suitable for surgical intervention. We enrolled 48 patients with CLI. Patients were randomized into two groups: the first group was treated with PLC, the second was treated with saline solution. All of them underwent the following tests: laser Doppler flowmetry at the forefoot at rest and after ischemia, trans cutaneous oxygen partial pressure and carbon dioxide partial pressure at the forefoot at rest and after ischemia, endothelium dependent dilation of the brachial artery. All tests were repeated after treatments. Pain was assessed by visual analog pain scale. Endothelium dependent dilation increased after PLC (9.5 ± 3.2 vs 4.9 ± 1.4 %; p < 0.05). Post-ischemic peak flow with laser-Doppler flow increased after PLC. TcPO2 increased, while TcPCO2 decreased after PLC; CO2 production decreased after PLC. VAS showed a significant reduction in pain perception after active treatment. In CLI patients, PLC can improve microcirculation (post ischemic hyperemia, TcPO2 and TcPCO2 production). PLC also enhances endothelium dependent dilation and reduces analgesic consumption and pain perception.

Retinal venous thrombosis in a young patient with coagulation factor XII deficiency.

PubMed

Borrego-Sanz, L; Santos-Bueso, E; Sáenz-Francés, F; Martínez-de-la-Casa, J M; García-Feijoo, J; Gegúndez-Fernández, J A; García-Sánchez, J

2014-08-01

A 35-year-old woman, with no relevant medical history, was referred for sudden vision loss in the left eye. Ophthalmological examination showed best corrected visual acuity of 1.0 in the right eye and 0.3 in left eye, with normal anterior pole and intraocular pressure. Fundus examination of the left eye revealed a venous thrombosis in the superior temporal branch, with dilated and tortuous retinal veins. The patient was referred to the hematology unit for thrombophilia study, and was diagnosed with a coagulation XII or Hageman factor deficiency. The development of retinal vessel occlusions, in patients under 50 years of age, is frequently associated with thrombophilia or hypercoagulability disorders. Factor XII deficiency is a rare condition, and its presence could contribute to a higher risk of thromboembolic events. Copyright © 2013 Sociedad Española de Oftalmología. Published by Elsevier Espana. All rights reserved.

Development of a low-cost multiple diode PIV laser for high-speed flow visualization

NASA Astrophysics Data System (ADS)

Bhakta, Raj; Hargather, Michael

2017-11-01

Particle imaging velocimetry (PIV) is an optical visualization technique that typically incorporates a single high-powered laser to illuminate seeded particles in a fluid flow. Standard PIV lasers are extremely costly and have low frequencies that severely limit its capability in high speed, time-resolved imaging. The development of a multiple diode laser system consisting of continuous lasers allows for flexible high-speed imaging with a wider range of test parameters. The developed laser system was fabricated with off-the-shelf parts for approximately 500. A series of experimental tests were conducted to compare the laser apparatus to a standard Nd:YAG double-pulsed PIV laser. Steady and unsteady flows were processed to compare the two systems and validate the accuracy of the multiple laser design. PIV results indicate good correlation between the two laser systems and verifies the construction of a precise laser instrument. The key technical obstacle to this approach was laser calibration and positioning which will be discussed. HDTRA1-14-1-0070.

Eye injuries from laser exposure: a review.

PubMed

Hudson, S J

1998-05-01

Lasers pose a significant threat to vision in modern military operations. Anti-personnel lasers have been designed that can cause intentional blindness in large numbers of personnel. Although the use of blinding laser weapons during combat has been prohibited by international legislation, research and development of these weapons have not been prohibited, and significant controversy remains. Unintentional blinding can also result from other types of lasers used on the battlefield, such as range-finders and anti-material lasers. Lasers that are capable of producing blindness operate within specific wavelength parameters and include visible and near infrared lasers. Patients who suffer from laser eye injuries usually complain of flash blindness, followed by transient or permanent visual loss. Laser retinal damage should be suspected in any patient with visual complaints in an operational setting. The treatment for laser retinal injuries is extremely limited, and prevention is essential. Improved protective eyeware and other countermeasures to laser eye injury are necessary as long as the threat remains.

COMPARISON OF RETINAL PATHOLOGY VISUALIZATION IN MULTISPECTRAL SCANNING LASER IMAGING.

PubMed

Meshi, Amit; Lin, Tiezhu; Dans, Kunny; Chen, Kevin C; Amador, Manuel; Hasenstab, Kyle; Muftuoglu, Ilkay Kilic; Nudleman, Eric; Chao, Daniel; Bartsch, Dirk-Uwe; Freeman, William R

2018-03-16

To compare retinal pathology visualization in multispectral scanning laser ophthalmoscope imaging between the Spectralis and Optos devices. This retrospective cross-sectional study included 42 eyes from 30 patients with age-related macular degeneration (19 eyes), diabetic retinopathy (10 eyes), and epiretinal membrane (13 eyes). All patients underwent retinal imaging with a color fundus camera (broad-spectrum white light), the Spectralis HRA-2 system (3-color monochromatic lasers), and the Optos P200 system (2-color monochromatic lasers). The Optos image was cropped to a similar size as the Spectralis image. Seven masked graders marked retinal pathologies in each image within a 5 × 5 grid that included the macula. The average area with detected retinal pathology in all eyes was larger in the Spectralis images compared with Optos images (32.4% larger, P < 0.0001), mainly because of better visualization of epiretinal membrane and retinal hemorrhage. The average detection rate of age-related macular degeneration and diabetic retinopathy pathologies was similar across the three modalities, whereas epiretinal membrane detection rate was significantly higher in the Spectralis images. Spectralis tricolor multispectral scanning laser ophthalmoscope imaging had higher rate of pathology detection primarily because of better epiretinal membrane and retinal hemorrhage visualization compared with Optos bicolor multispectral scanning laser ophthalmoscope imaging.

Laser-induced thermotherapy: an in-situ ablation technique for the local treatment of irresectable colorectal liver metastases

NASA Astrophysics Data System (ADS)

Ritz, Joerg-Peter; Isbert, Christoph M.; Roggan, Andre; Wacker, Frank; Buhr, Heinz-Johannes; Germer, Christoph-Thomas

2000-11-01

Laser-induced thermotherapy (LITT) is a so called in-situ- ablation technique which is used for the treatment of liver tumors. Coagulation necrosis is induced by transmitting the laser irradiation via quartz fibers directly into the tumor tissue. LITT represents similarly to surgical liver resection a local treatment form for liver metastases. The Nd-YAG laser (1064 nm) was used. The application system was placed percutaneously under open MRI control. On-line monitoring was done with MRI for evaluation of the postoperative follow-up we performed MRI-controls every 3 months. A total of 20 patients were treated. Due to the irradiation plan performed preoperatively, the treated tumors could be completely ablated by hyperthermia in all procedures. Complications were pleural effusion in 7 patients and a bile fistula and subcapsulary liver hematoma in one patient each. Local control of tumor growth can be achieved in tumors having undergone complete hyperthermic ablation. An assessment of the method regarding a prognostic benefit is not yet possible due to the short follow-up period and the small patient population.

Laser-induced interstitial thermotherapy (LITT) with the KTP 532 laser for the treatment of uterine adenomyosis

NASA Astrophysics Data System (ADS)

Chapman, Roxana; Chapman, Kenneth

1997-05-01

Adenomyosis is a condition in which the myometrium is infiltrated by endometrial glands and stroma. This results in myometrial hyperplasia, uterine enlargement and causes menorrhagia, dysmenorrhoea and dyspareunia for which there is no known cure other than hysterectomy. The success of LITT in the treatment of uterine leiomyomata suggested that this might also be effective for the treatment of adenomyosis. Initially LITT was carried out on patients with adenomyosis prior to hysterectomy, then on patients who had completed child-bearing and finally on those who desired a family. Not only were symptoms relieved but pregnancies occurred spontaneously. The KTP 532 nm component of the KTP/YAG laser, which is absorbed by red pigment, was used with a 600 micrometer fiber with a bare tip via a needle microstat at laparoscopy. Holes were drilled in the abnormal tissue 3 cm apart and the laser fiber then slowly withdrawn, the object being to coagulate the surrounding blood vessels and adenomyotic tissue. The number of joules required depended on the volume of tissue treated.

Laser-induced thermotherapy for the treatment of liver metastasis. Correlation of gadolinium-DTPA-enhanced MRI with histomorphologic findings to determine criteria for follow-up monitoring.

PubMed

Germer, C; Isbert, C M; Albrecht, D; Ritz, J P; Schilling, A; Roggan, A; Wolf, K J; Müller, G; Buhr, H

1998-11-01

To evaluate gadolinium (Gd)-diethylenetriamine-pentaacetic-acid (DTPA)-enhanced magnetic resonance imaging (MRI) for follow-up monitoring of laser-induced thermotherapy (LITT) and to determine a useful examination schedule. LITT of the liver was performed in 55 rabbits using a neodymium: yttrium-aluminum-garnet (Nd:YAG) laser (4-W power output, 840-s exposure time). Gd-DTPA MRI and histologic examinations were performed at different times (0-168 days). Laser-induced lesions underwent regeneration and volume size reduction (69% after 168 days). The correlation coefficient (MR vs. macroscopic analysis) for the mean lesion diameter was r = 0.96. Histology of lesions comprised the four zones that correlated best with MRI findings. Coagulation necroses immediately after LITT was seen as an area of no enhancement on Gd-DTPA MRI. Circular enhancement was first seen 72-96 h after LITT, which was due to early mesenchymal proliferation. Gd-DTPA MRI is a good monitoring procedure for LITT. MRI should be performed 24 and 96 h after LITT.

Holmium: yttrium aluminum garnet laser-assisted endoscopic sinus surgery: laboratory experience.

PubMed

Shapshay, S M; Rebeiz, E E; Bohigian, R K; Hybels, R L; Aretz, H T; Pankratov, M M

1991-02-01

Endoscopic sinus surgery has gained wide acceptance since its introduction into the United States. Complex sinus anatomy and troublesome bleeding have been associated with complications, which vary in severity from synechia to blindness and leakage of cerebrospinal fluid. Endoscopic sinus surgery using a holmium: yttrium aluminum garnet pulsed solid-state laser oscillating at 2.1 microns with fiberoptic delivery was performed in the laboratory, and the results were compared with those of conventional endoscopic sinus surgery. Three beagle dogs, six human cadaver heads, and one calf head were used in the in vivo and in vitro studies to evaluate the bone ablation, tissue coagulation, and hemostatic properties of the holmium: yttrium aluminum garnet laser. Modified endoscopic telescopes for sinus surgery, a newly developed handpiece for fiberoptic delivery, and other surgical instruments were used. The results indicate that the holmium: yttrium aluminum garnet laser and new delivery instrumentation provide good hemostasis and controlled soft-tissue ablation and bone removal. The access to all sinuses in the human cadaver model was very good. The canine in vivo study showed delayed but complete healing on the laser-treated side. Clinical evaluation of the holmium: yttrium aluminum garnet laser is warranted to increase the precision and safety of endoscopic sinus surgery.

Effective Management of a pregnancy tumour using a soft tissue diode laser: a case Report.

PubMed

Sharma, Ambika; Mathur, Vijay Prakash; Sardana, Divesh

2014-12-27

Pregnancy tumours (PTs) are a non-neoplastic, reactive, inflammatory conditional gingival enlargement which occurs in the oral cavity during pregnancy. The lesion most frequently occurs on the gingiva but may also develop on the lip, tongue, oral mucosa and palate. When a large PT develops, it can interfere with mastication, speech, maintenance of oral hygiene and can be aesthetically disfiguring. The treatment of PTs depends upon the size of the lesion; smaller lesions can regress after parturition however large lesions need to be surgically removed. Conventional surgical techniques have the disadvantage of more bleeding from the surgical site and delay in healing of the scar tissue. The diode laser is a relatively new alternative to conventional surgical technique in intra-oral areas with the added advantage of bloodless procedures and rapid healing. The purpose of the present study is to highlight the management of a PT in a 25-year-old female using a diode laser delivering a painless, bloodless procedure with rapid postoperative healing. Diode laser excision of a persistent pregnancy tumour in a postpartum patient was safe and effective with minimal bleeding, good coagulation, and good wound healing. Among other lasers, the diode laser can therefore be considered for excisional treatment of persistent PTs.

Liver repair and hemorrhage control using laser soldering of liquid albumin in a porcine model

NASA Astrophysics Data System (ADS)

Wadia, Yasmin; Xie, Hua; Kajitani, Michio; Gregory, Kenton W.; Prahl, Scott A.

2000-05-01

The purpose of this study was to evaluate laser soldering using liquid albumin for welding liver lacerations and sealing raw surfaces created by segmental resection of a lobe. Major liver trauma has a high mortality due to immediate exsanguination and a delayed morbidity and mortality from septicemia, peritonitis, biliary fistulae and delayed secondary hemorrhage. Eight laceration injuries (6 cm long X 2 cm deep) and eight non-anatomical resection injuries (raw surface 6 cm X 2 cm) were repaired. An 805 nm laser was used to weld 53% liquid albumin-ICG solder to the liver surface, reinforcing it with a free autologous omental scaffold. The animals were heparinized to simulate coagulation failure and hepatic inflow occlusion was used for vascular control. For both laceration and resection injuries, eight soldering repairs each were evaluated at three hours. A single suture repair of each type was evaluated at three hours. All 16 laser mediated liver repairs were accompanied by minimal blood loss as compared to the suture controls. No dehiscence, hemorrhage or bile leakage was seen in any of the laser repairs after three hours. In conclusion laser fusion repair of the liver is a quick and reliable technique to gain hemostasis on the cut surface as well as weld lacerations.

Needle tip visualization by bevel-point ultrasound generator and prototype photoacoustic imaging system

NASA Astrophysics Data System (ADS)

Irisawa, Kaku; Murakoshi, Dai; Hashimoto, Atsushi; Yamamoto, Katsuya; Hayakawa, Toshiro

2017-03-01

Visualization of the tip of medical devices like needles or catheters under ultrasound imaging has been a continuous topic since the early 1980's. In this study, a needle tip visualization system utilizing photoacoustic effects is proposed. In order to visualize the needle tip, an optical fiber was inserted into a needle. The optical fiber tip is placed on the needle bevel and affixed with black glue. The pulsed laser light from laser diode was transferred to the optical fiber and converted to ultrasound due to laser light absorption of the black glue and the subsequent photoacoustic effect. The ultrasound is detected by transducer array and reconstructed into photoacoustic images in the ultrasound unit. The photoacoustic image is displayed with a superposed ultrasound B-mode image. As a system evaluation, the needle is punctured into bovine meat and the needle tip is observed with commercialized conventional linear transducers or convex transducers. The needle tip is visualized clearly at 7 and 12 cm depths with linear and convex probes, respectively, even with a steep needle puncture angle of around 90 degrees. Laser and acoustic outputs, and thermal rise at the needle tip, were measured and were well below the limits of the safety standards. Compared with existing needle tip visualization technologies, the photoacoustic needle tip visualization system has potential distinguishable features for clinical procedures related with needle puncture and injection.

Usefullness of the ultrasonically activated scalpel in laparoscopic cholecystectomy: our experience and review of literature.

PubMed

Minutolo, V; Gagliano, G; Rinzivillo, C; Li Destri, G; Carnazza, M; Minutolo, O

2008-05-01

Laparoscopic cholecystectomy (LC) actually represents the most used and proper treatment for gallbladder lithiasis, because its many and known advantages in comparison with 'open' abdominal surgery. But there are some problems during and after LC due to the use of the electric scalpel and these have brought to the search of an alternative system of dissection and coagulation. The ultrasonically activated scalpel (Harmonic Scalpel, HS) allows to perform dissection and coagulation with a minimal thermal side effect for surrounding tissues, unlike the electrocoagulation. Furthermore, the use of the HS brings a series of advantages in comparison to the other electromagnetic forms of energy (electro-scalpel, laser). HS cuts and coagulates with the same effectiveness of the electro-scalpel but, unlike this, it doesn't introduce risks of wandering currents. Moreover, HS contributes to have a more clean and clear (smokes-free) field of operation and it reduces the operative time, the bleeding and the costs of the operation without an increase of the complications and of the percentages of 'open' conversion, and perhaps leads to a less negative influence on the postoperative systemic immune response. The Authors report their experience that confirm these observations, according also with results reported in a brief review of the recent scientific literature, and support wider diffusion and technical development of this ultrasonically-operating surgical team.

Development of transrectal diffuse optical tomography combined with 3D-transrectal ultrasound imaging to monitor the photocoagulation front during interstitial photothermal therapy of primary focal prostate cancer

NASA Astrophysics Data System (ADS)

He, Jie; Weersink, Robert; Veilleux, Israel; Mayo, Kenwrick; Zhang, Anqi; Piao, Daqing; Alam, Adeel; Trachtenberg, John; Wilson, Brian C.

2013-03-01

Interstitial near-infrared laser thermal therapy (LITT) is currently undergoing clinical trials as an alternative to watchful waiting or radical surgery in patients with low-risk focal prostate cancer. Currently, we use magnetic resonance image (MRI)-based thermography to monitor treatment delivery and determine indirectly the completeness of the target tissue destruction while avoiding damage to adjacent normal tissues, particularly the rectal wall. However, incomplete tumor destruction has occurred in a significant fraction of patients due to premature termination of treatment, since the photocoagulation zone is not directly observed. Hence, we are developing transrectal diffuse optical tomography (TRDOT), in combination with transrectal 3D ultrasound (3D-TRUS), to address his limitation. This is based on the large changes in optical scattering expected upon tissue coagulation. Here, we present forward simulations of a growing coagulated lesion with optical scattering contrast, using an established finite element analysis software platform (NIRFAST). The simulations were validated in tissue-simulating phantoms, with measurements acquired by a state-of-the-art continuous wave (CW) TRDOT system and a recently assembled bench-top CW-DOT system, with specific source-detector configurations. Two image reconstruction schemes were investigated and evaluated, specifically for the accurate delineation of the posterior boundary of the coagulation zone as the critical parameter for treatment guidance in this clinical application.

Clinical development of holmium:YAG laser prostatectomy

NASA Astrophysics Data System (ADS)

Kabalin, John N.

1996-05-01

Holmium:YAG (Ho:YAG) laser vaporization and resection of the prostate offers advantages in immediate tissue removal compared to the Neodymium:YAG (Nd:YAG) laser. Ongoing development of appropriate operative techniques and Ho:YAG laser delivery systems suitable for endoscopic prostate surgery, including side-firing optical delivery fibers, have facilitated this approach. We performed Ho:YAG laser prostatectomy in 20 human subjects, including 2 men treated immediately prior to radical prostatectomy to assess Ho:YAG laser effects in the prostate. A total of 18 men were treated in an initial clinical trial of Ho:YAG prostatectomy. Estimated excess hyperplastic prostate tissue averaged 24 g (range 5 - 50 g). A mean of 129 kj Ho:YAG laser energy was delivered, combined with a mean of 11 kj Nd:YAG energy to provide supplemental coagulation for hemostasis. We have observed no significant perioperative or late complications. No significant intraoperative changes in hematocrit or serum electrolytes were documented. In addition to providing acute removal of obstructing prostate tissue, Ho:YAG laser resection allowed tissue specimen to be obtained for histologic examination. A total of 16 of 18 patients (90%) underwent successful removal of their urinary catheter and voiding trial within 24 hours following surgery. Immediate improvement in voiding, comparable to classic transurethral electrocautery resection of the prostate (TURP), was reported by all patients. Ho:YAG laser resection of the prostate appears to be a viable surgical technique associated with minimal morbidity and immediate improvement in voiding.

Combined pulsed dye laser and fiberoptic Nd-YAG laser for the treatment of hypertrophic port wine stain.

PubMed

Radmanesh, Mohammed; Radmanesh, Ramin

2017-10-01

The hypertrophic Port Wine Stain (PWS) is only partially and superficially treated with the Pulsed dye laser (PDL) because of its limited depth of penetration. We used combined PDL and fiberoptic 1444-nm Nd-YAG laser to treat a case with hypertrophic PWS. After tumescent anesthesia, few holes were made by a 16-gauge needle on different sides of the lesion. The fiberoptic tip of 1444-nm Nd-YAG laser was inserted within the holes and was pushed forward while triggering. In a fan pattern and by a back and forth movement, the subcutaneous and deep dermal areas were coagulated. The skin and outer mucosal surfaces were then treated by PDL. The fiberoptic system used was Accusculpt 1444-nm Nd-YAG laser (Lutronic lasers, South Korea), and the PDL used was 585 nm Nlite system (Chromogenex UK). The parameters used for PDL were fluence = 9 Joules/cm 2 and the spot size was 5 mm. The parameters used for fiberoptic 1444-nm Nd-YAG laser were: Pulse rate = 30 Hz, pulse energy = 300 mJ, power = 6 W, and the total energy = 4000 J for the whole face and mucosa. Little sign of regression and moderate purpura were detected immediately after combined fiberoptic Nd-YAG and PDL therapy. The lesion gradually regressed within 4 months with satisfactory color and volume change. Combined fiberoptic Nd-YAG laser and PDL can be used for the treatment of deeper and superficial layers of hypertrophic PWS.

GreenLight laser vs diode laser vaporization of the prostate: 3-year results of a prospective nonrandomized study.

PubMed

Guo, Sanwei; Müller, Georg; Bonkat, Gernot; Püschel, Heike; Gasser, Thomas; Bachmann, Alexander; Rieken, Malte

2015-04-01

Laser vaporization of the prostate is one of the alternatives to transurethral resection of the prostate. Short-term studies report a comparable outcome after laser vaporization with the 532 nm 120-W GreenLight high-performance system (HPS) laser and the 980 nm 200 W high-intensity diode (diode) laser. In this study, we analyzed the intermediate-term results of both techniques. From January 2007 to January 2008, 112 consecutive patients with symptomatic benign prostate enlargement were nonrandomly assigned to treatment with the GreenLight laser or the diode laser. Perioperative parameters, postoperative functional outcome, complications, and the reoperation rate at 3 years were analyzed. Improvement of voiding symptoms (International Prostate Symptom Score, quality-of-life) and micturition parameters (maximum flow rate, postvoid residual volume) showed no significant difference between the HPS group and the diode group. A significantly higher reoperation rate was observed in the diode group in comparison to the HPS group (37.5% vs 8.9%, p=0.0003) due to obstructive necrotic tissue (16.1% vs 0%, p=0.0018), bladder neck stricture (16.1% vs 1.8%, p=0.008), and persisting or recurrent adenoma (5.4% vs 7.1%, p=0.70), respectively. Both lasers lead to comparable improvement of voiding parameters and micturition symptoms. Treatment with the 200 W diode laser led to a significantly higher reoperation rate, which might be attributed to a higher degree of coagulation necrosis. Thus, a careful clinical application of this diode laser type is warranted.

Orange fiber laser for ophthalmology

NASA Astrophysics Data System (ADS)

Adachi, M.; Kojima, K.; Hayashi, K.

2007-02-01

For the light source of photocoagulators for ophthalmology, orange laser is more suitable than green laser because of low scattering loss by the crystalline lens, and low absorption by xanthophylls in the retina. We developed two orange fiber lasers (580 nm and 590 nm) to investigate the effect depending on the difference in the range of orange. The 580nm laser is composed of a 1160 nm fiber laser and a Periodically Polled Lithium Niobate (PPLN) crystal for second harmonic generation. The 1160 nm fiber laser beam is focused into the MgO-doped PPLN crystal whose length is 30 mm with 3-pass configuration. Continuous-wave 1.3 W output power of 580 nm was obtained with 5.8 W input power of 1160nm for the first time. The conversion efficiency was 22%. The band width of the second harmonic was 0.006 nm (FWHM). The 590 nm laser is almost the same as 580 nm laser source. In this case we used a Raman shift fiber to generate 1180 nm, and the output power of 590 nm was 1.4 W. We developed an evaluation model of photocoagulator system using these two laser sources. A 700 mW coagulation output power was obtained with this orange fiber laser photocoagulator system. This is enough power for the eye surgery. We have the prospect of the maintenance-free, long-life system that is completely air-cooled. We are planning to evaluate this photocoagulator system in order to investigate the difference between the two wavelengths at the field test.

Aircrew laser eye protection: visual consequences and mission performance.

PubMed

Thomas, S R

1994-05-01

Battlefield laser proliferation poses a mounting risk to aircrew and ground personnel. Laser eye protection (LEP) based on current mature, mass-producible technologies absorbs visible light and can impact visual performance and color identification. These visual consequences account for many of the mission incompatibilities associated with LEP. Laboratory experiments and field investigations that examined the effects of LEP on visual performance and mission compatibility are reviewed. Laboratory experiments assessed the ability of subjects to correctly read and identify the color of head-down display symbology and tactical pilotage charts (TPC's) with three prototype LEP visors. Field investigations included Weapons Systems Trainer (WST), ground, and flight tests of the LEP visors. Recommendations for modifying aviation lighting systems to improve LEP compatibility are proposed. Issues concerning flight safety when using LEP during air operation are discussed.

The Relationship between OCT-measured Central Retinal Thickness and Visual Acuity in Diabetic Macular Edema

PubMed Central

2008-01-01

Objective To compare optical coherence tomography (OCT)-measured retinal thickness and visual acuity in eyes with diabetic macular edema (DME) both before and after macular laser photocoagulation. Design Cross-sectional and longitudinal study. Participants 210 subjects (251 eyes) with DME enrolled in a randomized clinical trial of laser techniques. Methods Retinal thickness was measured with OCT and visual acuity was measured with the electronic-ETDRS procedure. Main Outcome Measures OCT-measured center point thickness and visual acuity Results The correlation coefficients for visual acuity versus OCT center point thickness were 0.52 at baseline and 0.49, 0.36, and 0.38 at 3.5, 8, and 12 months post-laser photocoagulation. The slope of the best fit line to the baseline data was approximately 4.4 letters (95% C.I.: 3.5, 5.3) better visual acuity for every 100 microns decrease in center point thickness at baseline with no important difference at follow-up visits. Approximately one-third of the variation in visual acuity could be predicted by a linear regression model that incorporated OCT center point thickness, age, hemoglobin A1C, and severity of fluorescein leakage in the center and inner subfields. The correlation between change in visual acuity and change in OCT center point thickening 3.5 months after laser treatment was 0.44 with no important difference at the other follow-up times. A subset of eyes showed paradoxical improvements in visual acuity with increased center point thickening (7–17% at the three time points) or paradoxical worsening of visual acuity with a decrease in center point thickening (18%–26% at the three time points). Conclusions There is modest correlation between OCT-measured center point thickness and visual acuity, and modest correlation of changes in retinal thickening and visual acuity following focal laser treatment for DME. However, a wide range of visual acuity may be observed for a given degree of retinal edema and paradoxical increases in center point thickening with increases in visual acuity as well as paradoxical decreases in center point thickening with decreases in visual acuity were not uncommon. Thus, although OCT measurements of retinal thickness represent an important tool in clinical evaluation, they cannot reliably substitute as a surrogate for visual acuity at a given point in time. This study does not address whether short-term changes on OCT are predictive of long-term effects on visual acuity. PMID:17123615

Contact Nd:YAG tonsillectomy: effects on weight loss and recovery.

PubMed

Maloney, R W

1991-01-01

Contact Nd:YAG tonsillectomy using synthetic sapphire blades appears to meet or exceed standards established by spot monopolar cautery. Subjects' percentage of weight loss and return to work/social activities was measured and the laser group displayed less percentage of weight loss, faster return to pre-operative weight, and less recovery time than the comparative cautery group. Because of the unique nature of Nd:YAG laser light combined with sapphire blades, special consideration should be given to these accessories by physicians before attempting tissue cutting and vessel coagulation. The author believes that the extent of physician training and proficiency may be key to the success of soft tissue head and neck applications, such as tonsillectomy, which will have an effect on the outcome of clinical data.

Effect of anterior capsule contraction on visual function after cataract surgery.

PubMed

Hayashi, Ken; Hayashi, Hideyuki

2007-11-01

To examine the effect of contraction of the anterior capsule opening after cataract surgery on visual acuity and contrast sensitivity. Hayashi Eye Hospital, Fukuoka, Japan. Thirty-two eyes of 32 consecutive patients who showed marked contraction of the anterior capsule opening after implantation of an intraocular lens were recruited. The area of the anterior capsule opening was measured by Scheimpflug videophotography before and after neodymium:YAG (Nd:YAG) laser anterior capsulotomy and was correlated with visual acuity and contrast sensitivity. After Nd:YAG laser anterior capsulotomy, the mean area of the anterior capsule opening increased significantly from 8.2 mm(2) to 18.0 mm(2) (P<.0001). Contrast sensitivity at most visual angles also improved significantly after Nd:YAG anterior capsulotomy, although visual acuity did not. The area of the anterior capsule opening before anterior capsulotomy was correlated significantly with contrast sensitivity but not with visual acuity, whereas there was no correlation between the opening area after anterior capsulotomy and visual acuity or contrast sensitivity. Contraction of the anterior capsule opening after cataract surgery significantly diminished contrast sensitivity in proportion to the opening area but did not markedly worsen visual acuity. Neodymium:YAG laser anterior capsulotomy improved contrast sensitivity.

Accidental human laser retinal injuries from military laser systems

NASA Astrophysics Data System (ADS)

Stuck, Bruce E.; Zwick, Harry; Molchany, Jerome W.; Lund, David J.; Gagliano, Donald A.

1996-04-01

The time course of the ophthalmoscopic and functional consequences of eight human laser accident cases from military laser systems is described. All patients reported subjective vision loss with ophthalmoscopic evidence of retinal alteration ranging from vitreous hemorrhage to retinal burn. Five of the cases involved single or multiple exposures to Q-switched neodymium radiation at close range whereas the other three incidents occur over large ranges. Most exposures were within 5 degrees of the foveola, yet none directly in the foveola. High contrast visual activity improved with time except in the cases with progressive retinal fibrosis between lesion sites or retinal hole formation encroaching the fovea. In one patient the visual acuity recovered from 20/60 at one week to 20/25 in four months with minimal central visual field loss. Most cases showed suppression of high and low spatial frequency contrast sensitivity. Visual field measurements were enlarged relative to ophthalmoscopic lesion size observations. Deep retinal scar formation and retinal traction were evident in two of the three cases with vitreous hemorrhage. In one patient, nerve fiber layer damage to the papillo-macular bundle was clearly evident. Visual performance measured with a pursuit tracking task revealed significant performance loss relative to normal tracking observers even in cases where acuity returned to near normal levels. These functional and performance deficits may reflect secondary effects of parafoveal laser injury.

[Vein morphology after endovenous laser coagulation at different power and similar linear density of energy].

PubMed

Fokin, A A; Borsuk, D A; Kazachkov, E L; Gorelik, G L; Bagaev, K V

The purpose of the study was to assess the depth of damage to the venous wall after endovenous laser coagulation (EVLC) at different power of the unit - 5, 7 and 10 W and similar linear density of energy (LDE) - approximately 70 J/cm. Our prospective comparative morphological study with blinding included a total of 30 patients subjected to EVLC of the great saphenous vein using the unit with a wavelength of 1,470 nm and radial light guides with automatic traction. The patients were divided into three groups, each comprising 10 patients. The unit's power (W) during EVLC and velocity of light guide traction (mm/s) in group one amounted to 5 and 0.7 (LDE - 71.4 J/cm), in group two to 7 and 1.0 (LDE - 70 J/cm) and in group tree to 10 and 1.5 (LDE - 66.7 J/cm), respectively. The coagulated veins were then procured from mini approaches and subjected to three sections made at a distance of 2 mm from each other. Specimens were stained with haematoxylin-eosin and picrofuxin according to the van Gieson technique. Then, in four places of each section (at 3, 6, 9 and 12 hours) we assessed the depth of the damage to the venous wall and calculated the average percentage of alteration - the ratio of the depth of the lesion to the venous wall thickness. The average depth of damage to the venous wall (μm) amounted in the first group to 122.9 ?m, in the second group to 182.9 μm, and in the third group to 267 μmm. The index of alteration (%) averagely amounted: in group one to 25.7, in group two to 37.9 and in group three (at a power of 10 W) to 55.5 (p=0.0001 when comparing each of the groups (the Kruskal-Wallis test)). Hence, despite an inconsiderable decrease of the LDE from the first to the third group, as power increased, the depth and percentage of damage to venous walls increased statistically significantly. It follows from the above-mentioned that: 1) an increase in power (from 5 to 10 W) of the unit during EVLC at comparable LDE (approximately 70 J/cm) leads to a deeper damage of the venous wall; 2) it is necessary to carry out a clinical study aimed at comparing different modes of coagulation, with the assessment of the frequency of recanalization and the level of pain syndrome.

Visual servoing of a laser ablation based cochleostomy

NASA Astrophysics Data System (ADS)

Kahrs, Lüder A.; Raczkowsky, Jörg; Werner, Martin; Knapp, Felix B.; Mehrwald, Markus; Hering, Peter; Schipper, Jörg; Klenzner, Thomas; Wörn, Heinz

2008-03-01

The aim of this study is a defined, visually based and camera controlled bone removal by a navigated CO II laser on the promontory of the inner ear. A precise and minimally traumatic opening procedure of the cochlea for the implantation of a cochlear implant electrode (so-called cochleostomy) is intended. Harming the membrane linings of the inner ear can result in damage of remaining organ functions (e.g. complete deafness or vertigo). A precise tissue removal by a laser-based bone ablation system is investigated. Inside the borehole the pulsed laser beam is guided automatically over the bone by using a two mirror galvanometric scanner. The ablation process is controlled by visual servoing. For the detection of the boundary layers of the inner ear the ablation area is monitored by a color camera. The acquired pictures are analyzed by image processing. The results of this analysis are used to control the process of laser ablation. This publication describes the complete system including image processing algorithms and the concept for the resulting distribution of single laser pulses. The system has been tested on human cochleae in ex-vivo studies. Further developments could lead to safe intraoperative openings of the cochlea by a robot based surgical laser instrument.

Database structure for the Laser Accident and Incident Registry (LAIR)

NASA Astrophysics Data System (ADS)

Ness, James W.; Hoxie, Stephen W.; Zwick, Harry; Stuck, Bruce E.; Lund, David J.; Schmeisser, Elmar T.

1997-05-01

The ubiquity of laser radiation in military, medical, entertainment, telecommunications and research industries and the significant risk, of eye injury from this radiation are firmly established. While important advances have been made in understanding laser bioeffects using animal analogues and clinical data, the relationships among patient characteristics, exposure conditions, severity of the resulting injury, and visual function are fragmented, complex and varied. Although accident cases are minimized through laser safety regulations and control procedures, accumulated accident case information by the laser eye injury evaluation center warranted the development of a laser accident and incident registry. The registry includes clinical data for validating and refining hypotheses on injury and recovery mechanisms; a means for analyzing mechanisms unique to human injury; and a means for identifying future areas of investigation. The relational database supports three major sections: (1) the physics section defines exposure circumstances, (2) the clinical/ophthalmologic section includes fundus and scanning laser ophthalmoscope images, and (3) the visual functions section contains specialized visual function exam results. Tools are available for subject-matter experts to estimate parameters like total intraocular energy, ophthalmic lesion grade, and exposure probability. The database is research oriented to provide a means for generating empirical relationships to identify symptoms for definitive diagnosis and treatment of laser induced eye injuries.

No advanced retinopathy of prematurity stages 4 or 5 in a large high-risk German cohort.

PubMed

Muether, Philipp S; Kribs, Angela; Hahn, Moritz; Schumacher, Jasmin; Eifinger, Frank; Kirchhof, Bernd; Roth, Bernhard; Fauser, Sascha

2012-03-01

Retinopathy of prematurity (ROP) remains a major cause of juvenile blindness. As screening recommendations are refined, decreasing gestational age (GA) and birth weight (BW) constitute an increasing risk for ROP. This retrospective case series reviews the screening results of a very immature cohort in Germany. We conducted ROP screening according to the German guidelines of 1999: all preterm infants with a GA of < 32 weeks and/or a BW of < 1501 g, or with GA ≥ 32 weeks and postnatal oxygen treatment for > 3 days, were assigned for screening. Dense laser coagulation was performed according to the current treatment criteria. All 767 consecutive inborn (patients born at the Department of Neonatology, University Hospital of Cologne, Germany) preterm infants of a tertiary medical centre of maximum care underwent complete screening from 2001 to 2009. The treatment incidence was 7.0%. No preterm infant developed stage 4/5 ROP. Mean GA and BW of untreated/treated preterm infants were 28.4/24.6 weeks and 1109/635 g, respectively. Increasing treatment incidence was associated with lower GA, but not with lower BW in logistic regression analysis. In this very immature high-risk cohort, advanced stages 4 and 5 were avoided throughout 9 years of screening. We suggest three factors that contributed to this outcome: (1) strict adherence to current ROP screening and treatment guidelines; (2) prompt and very dense laser coagulation if necessary; and (3) a specialised neonatal intensive care unit with experience of very immature babies.

Porphyrin-laser photodynamic induction of focal brain necrosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stroop, W.G.; Battles, E.J.; Townsend, J.J.

A noninvasive photodynamic method has been developed to produce focal brain necrosis using porphyrin activated in vivo with laser light. After peripheral injection of the photosensitive porphyrin derivative, Photofrin I, mice were irradiated on the posterior lateral aspect of the head through the intact depilated scalp with 632 nm argon-dye laser light. Animals were studied at one, two and seven days after irradiation. Blood-brain barrier damage was detected by the intravenous injection of Evans blue, horseradish peroxidase and heterologous immunoglobulins. At one and two days after irradiation, the lesions were characterized by extravasation of immunoglobulin and Evans blue, and bymore » edema, ischemia and infiltration by monocytes. On the seventh day after irradiation, the lesion was smaller than it had been two days after irradiation, and had reactive changes at its edges and coagulative necrosis at its center. Extravasation of Evans blue and immunoglobulin was markedly reduced by the seventh day after irradiation, but uptake of horseradish peroxidase by macrophages located at the periphery of the lesion was evident.« less

Automatic Tracking Algorithm in Coaxial Near-Infrared Laser Ablation Endoscope for Fetus Surgery

NASA Astrophysics Data System (ADS)

Hu, Yan; Yamanaka, Noriaki; Masamune, Ken

2014-07-01

This article reports a stable vessel object tracking method for the treatment of twin-to-twin transfusion syndrome based on our previous 2 DOF endoscope. During the treatment of laser coagulation, it is necessary to focus on the exact position of the target object, however it moves by the mother's respiratory motion and still remains a challenge to obtain and track the position precisely. In this article, an algorithm which uses features from accelerated segment test (FAST) to extract the features and optical flow as the object tracking method, is proposed to deal with above problem. Further, we experimentally simulate the movement due to the mother's respiration, and the results of position errors and similarity verify the effectiveness of the proposed tracking algorithm for laser ablation endoscopy in-vitro and under water considering two influential factors. At average, the errors are about 10 pixels and the similarity over 0.92 are obtained in the experiments.

Laser light visual cueing for freezing of gait in Parkinson disease: A pilot study with male participants.

PubMed

Bunting-Perry, Lisette; Spindler, Meredith; Robinson, Keith M; Noorigian, Joseph; Cianci, Heather J; Duda, John E

2013-01-01

Freezing of gait (FOG) is a debilitating feature of Parkinson disease (PD). In this pilot study, we sought to assess the efficacy of a rolling walker with a laser beam visual cue to treat FOG in PD patients. We recruited 22 subjects with idiopathic PD who experienced on- and off-medication FOG. Subjects performed three walking tasks both with and without the laser beam while on medications. Outcome measures included time to complete tasks, number of steps, and number of FOG episodes. A crossover design allowed within-group comparisons between the two conditions. No significant differences were observed between the two walking conditions across the three tasks. The laser beam, when applied as a visual cue on a rolling walker, did not diminish FOG in this study.

Topographic steep central islands following excimer laser photorefractive keratectomy

NASA Astrophysics Data System (ADS)

Krueger, Ronald R.; McDonnell, Peter J.

1994-06-01

The purpose of this study is to demonstrate that topographic irregularities in the form of central islands of higher refractive power can be seen following excimer laser refractive surgery. We reviewed the computerized corneal topographic maps of 35 patients undergoing excimer laser PRK for compound myopic astigmatism or anisometropia from 8/91 to 8/93 at the USC/Doheny Eye Institute. The topographic maps were generated by the Computed Anatomy Corneal Modeling System, and central islands were defined as topographic areas of steepening of at least 3 diopters and 3 mm in diameter. A grading system was developed based on the presence of central islands during the postoperative period. Visually significant topographic steep central islands may be seen in over 50% of patients at 1 month following excimer laser PRK, and persist at 3 months in up to 24% of patients without nitrogen gas blowing. Loss of best corrected visual acuity or ghosting is associated with island formation, and may prolong visual rehabilitation after excimer laser PRK.

Comparison of KTP, Thulium, and CO2 laser in stapedotomy using specialized visualization techniques: thermal effects.

PubMed

Kamalski, Digna M A; Verdaasdonk, Rudolf M; de Boorder, Tjeerd; Vincent, Robert; Trabelzini, Franco; Grolman, Wilko

2014-06-01

High-speed thermal imaging enables visualization of heating of the vestibule during laser-assisted stapedotomy, comparing KTP, CO2, and Thulium laser light. Perforation of the stapes footplate with laser bears the risk of heating of the inner ear fluids. The amount of heating depends on absorption of the laser light and subsequent tissue ablation. The ablation of the footplate is driven by strong water absorption for the CO2 and Thulium laser. For the KTP laser wavelength, ablation is driven by carbonization of the footplate and it might penetrate deep into the inner ear without absorption in water. The thermal effects were visualized in an inner ear model, using two new techniques: (1) high-speed Schlieren imaging shows relative dynamic changes of temperatures up to 2 ms resolution in the perilymph. (2) Thermo imaging provides absolute temperature measurements around the footplate up to 40 ms resolution. The high-speed Schlieren imaging showed minimal heating using the KTP laser. Both CO2 and Thulium laser showed heating below the footplate. Thulium laser wavelength generated heating up to 0.6 mm depth. This was confirmed with thermal imaging, showing a rise of temperature of 4.7 (±3.5) °C for KTP and 9.4 (±6.9) for Thulium in the area of 2 mm below the footplate. For stapedotomy, the Thulium and CO2 laser show more extended thermal effects compared to KTP. High-speed Schlieren imaging and thermal imaging are complimentary techniques to study lasers thermal effects in tissue.

New surgical treatment options in patients with benign prostate hyperplasia (BPH)

NASA Astrophysics Data System (ADS)

de Riese, Werner T. W.; Nelius, Thomas; Aronoff, David R.; Mittemeyer, Bernhard T.

2003-06-01

Benign prostatic hyperplasia (BPH) is a common disease in males older than 50 years of age. 75-80% of this population is considered to have some degree of BPH causing clinical symptoms and requiring urological treatment. Transurethral resection of the prostate (TUR-P) is currently the standard surgical treatment modality for BPH. In an attempt to minimize the need for hospitalization and the associated perioperative and postoperative morbidity, alternatives have been sought. Various types of Laser techniques such as interstitial Laser cogaulation and side-firing technology have been proposed. Numerous studies have shown that Laser procedures safely and effectively reduce the volume of the prostate. Intra- and postoperative bleeding are nearly unknown complications for Laser procedures, whereas this is the most relevant complication for the TUR-P. Due to significant tissue edema after Laser treatment, patients commonly show delayed time to void adequately, and therefore, catheter drainage is often necessary for 3 to 21 days. Retrograde ejaculation is reported to occur less (0 - 10%) compared to TUR-P (> 60%). Urinary tract infections are very common after interstitial laser coagulation. Although not many long-term clinical data are available, various studies have shown that BPH patients improve in symptom score, flow rate and post-void residual up to 3 years after Laser treatment. This paper presents a concise review of efficacy, advantages and disadvantages of the most frequently used Laser techniques as well as the long-term clinical data compared to TUR-P.

Ablation of intervertebral discs in dogs using a MicroJet-assisted dye-enhanced injection device coupled with the diode laser

NASA Astrophysics Data System (ADS)

Bartels, Kenneth E.; Henry, George A.; Dickey, D. Thomas; Stair, Ernest L.; Powell, Ronald; Schafer, Steven A.; Nordquist, Robert E.; Frederickson, Christopher J.; Hayes, Donald J.; Wallace, David B.

1998-07-01

Use of holmium laser energy for vaporization/coagulation of the nucleus pulposus in canine intervertebral discs has been previously reported and is currently being applied clinically in veterinary medicine. The procedure was originally developed in the canine model and intended for potential human use. Since the pulsed (15 Hz) holmium laser energy exerts photomechanical and photothermal effects, the potential for extrusion of additional disc material to the detriment of the patient is possible using the procedure developed for the dog. To reduce this potential complication, use of diode laser (805 nm - CW mode) energy, coupled with indocyanine green (ICG) as a selective laser energy absorber, was formulated as a possible alternative. Delivery of the ICG and diode laser energy was through a MicroJet device that could dispense dye interactively between individual laser 'shots.' Results have shown that it is possible to selectively ablate nucleus pulposus in the canine model using the device described. Acute observations (gross and histopathologic) illustrate that accurate placement of the spinal needle before introduction of the MicroJet device is critically dependent on the expertise of the interventional radiologist. In addition, the success of the overall technique depends on consistent delivery of both ICG and diode laser energy. Minimizing tissue carbonization on the tip of the MicroJet device is also of crucial importance for effective application of the technique in clinical veterinary medicine.

Precision resection of lung cancer in a sheep model using ultrashort laser pulses

NASA Astrophysics Data System (ADS)

Beck, Rainer J.; Mohanan, Syam Mohan P. C.; Góra, Wojciech S.; Cousens, Chris; Finlayson, Jeanie; Dagleish, Mark P.; Griffiths, David J.; Shephard, Jonathan D.

2017-02-01

Recent developments and progress in the delivery of high average power ultrafast laser pulses enable a range of novel minimally invasive surgical procedures. Lung cancer is the leading cause of cancer deaths worldwide and here the resection of lung tumours by means of picosecond laser pulses is presented. This represents a potential alternative to mitigate limitations of existing surgical treatments in terms of precision and collateral thermal damage to the healthy tissue. Robust process parameters for the laser resection are demonstrated using ovine pulmonary adenocarcinoma (OPA). OPA is a naturally occurring lung cancer of sheep caused by retrovirus infection that has several features in common with some forms of human pulmonary adenocarcinoma, including a similar histological appearance, which makes it ideally suited for this study. The picosecond laser was operated at a wavelength of 515 nm to resect square cavities from fresh ex-vivo OPA samples using a range of scanning strategies. Process parameters are presented for efficient ablation of the tumour with clear margins and only minimal collateral damage to the surrounding tissue. The resection depth can be controlled precisely by means of the pulse energy. By adjusting the overlap between successive laser pulses, deliberate heat transfer to the tissue and thermal damage can be achieved. This can be beneficial for on demand haemostasis and laser coagulation. Overall, the application of ultrafast lasers for the resection of lung tumours has potential to enable significantly improved precision and reduced thermal damage to the surrounding tissue compared to conventional techniques.

Characteristics of Nd:YAG sculptured contact probes after prolonged laser application.

PubMed

Barroso, E G; Haklin, M F; Staren, E D

1995-01-01

This study analyzed the functional and structural characteristics of cone, hemisphere, and modified sculptured contact fibers (1,000 microns) after 1 hour of continuous Nd:YAG laser application. Continuous laser application was performed on live porcine tissue using 20 watts of power. The fiber's appearance under a microscope as well as the power output was recorded after 0, 5, 10, 20, 30, 45, and 60 minutes of continuous laser application. (N = 3 for each fiber). At time 0, all fibers transmitted from 49 to 56% of the initial 20 watts (W); power transmission decreased to less than 9% relative power transmission after 20 minutes and then plateaued. The fibers exhibited severe distortion and carbonization of the surface where laser had been applied with evidence of quartz melting and shattering after only 10 minutes. By 30 minutes of laser application, all three fibers were fractured and essentially indistinguishable from one another; moreover, the fibers exhibited similar power transmission, and cutting and coagulation activity, as determined by a panel of independent, double-blinded surgeons. These data lead us to conclude that 1) Nd:YAG contact laser effects result from thermal heating of the fiber tip with subsequent tissue injury, 2) the unique structural configuration of the fiber's sculptured tip are lost after several minutes of laser application without appreciable change in functional integrity, and 3) fibers may be manually fractured allowing for multiple uses without significant sacrifice of power transmission or surgical utility.

Residual anastomoses in twin-twin transfusion syndrome after laser: the Solomon randomized trial.

PubMed

Slaghekke, Femke; Lewi, Liesbeth; Middeldorp, Johanna M; Weingertner, Anne Sophie; Klumper, Frans J; Dekoninck, Philip; Devlieger, Roland; Lanna, Mariano M; Deprest, Jan; Favre, Romain; Oepkes, Dick; Lopriore, Enrico

2014-09-01

Residual anastomoses after fetoscopic laser surgery for twin-to-twin transfusion syndrome (TTTS) may lead to severe postoperative complications, including recurrent TTTS and twin anemia-polycythemia sequence (TAPS). A novel technique (Solomon technique) using laser coagulation of the entire vascular equator was recently investigated in a randomized controlled trial (Solomon trial) and compared with the Standard selective laser technique. The aim of this secondary analysis was to evaluate the occurrence and characteristics of residual anastomoses in placentas included in the Solomon trial. International multicenter randomized controlled trial in TTTS, randomized 1:1 ratio to either the Solomon laser technique or Standard laser technique. At time of laser, surgeons recorded whether they considered the procedure to be complete. Placental dye injection was performed after birth in the participating centers to evaluate the presence of residual anastomoses. A total of 151 placentas were included in the study. The percentage of placentas with residual anastomoses in the Solomon group and Standard group was 19% (14/74) and 34% (26/77), respectively (P = .04). The percentage of placentas with residual anastomoses in the subgroup of cases where the procedure was recorded as complete was 8/65 (12%) and 22/69 (32%) in the Solomon group and Standard group, respectively (P < .01). The Solomon laser technique reduces the risk of residual anastomoses. However, careful follow-up remains essential also after the Solomon technique, as complete dichorionization is not always achieved. Copyright © 2014 Mosby, Inc. All rights reserved.

YAG Laser Vitreolysis vs Sham YAG Vitreolysis for Symptomatic Vitreous Floaters: A Randomized Clinical Trial.

PubMed

Shah, Chirag P; Heier, Jeffrey S

2017-09-01

Vitreous floaters are common and can worsen visual quality. YAG vitreolysis is an untested treatment for floaters. To evaluate YAG laser vitreolysis vs sham vitreolysis for symptomatic Weiss ring floaters from posterior vitreous detachment. This single-center, masked, sham-controlled randomized clinical trial was performed from March 25, 2015, to August 3, 2016, in 52 eyes of 52 patients (36 cases and 16 controls) treated at a private ophthalmology practice. Patients were randomly assigned to YAG laser vitreolysis or sham YAG (control). Primary 6-month outcomes were subjective change measured from 0% to 100% using a 10-point visual disturbance score, a 5-level qualitative scale, and National Eye Institute Visual Functioning Questionnaire 25 (NEI VFQ-25). Secondary outcomes included objective change assessed by masked grading of color fundus photography and Early Treatment Diabetic Retinopathy Study best-corrected visual acuity. Fifty-two patients (52 eyes; 17 men and 35 women; 51 white and 1 Asian) with symptomatic Weiss rings were enrolled in the study (mean [SD] age, 61.4 [8.0] years for the YAG laser group and 61.1 [6.6] years for the sham group). The YAG laser group reported greater symptomatic improvement (54%) than controls (9%) (difference, 45%; 95% CI, 25%-64%; P < .001). In the YAG laser group, the 10-point visual disturbance score improved by 3.2 vs 0.1 in the sham group (difference, -3.0; 95% CI, -4.3 to -1.7; P < .001). A total of 19 patients (53%) in the YAG laser group reported significantly or completely improved symptoms vs 0 individuals in the sham group (difference, 53%; 95% CI, 36%-69%, P < .001). Compared with sham, NEI VFQ-25 revealed improved general vision (difference, 16.3; 95% CI, 0.9-31.7; P = .04), peripheral vision (difference, 11.6; 95% CI, 0.8-22.4; P = .04), role difficulties (difference, 17.3; 95% CI, 8.0-26.6; P < .001), and dependency (difference, 5.6; 95% CI, 0.5-10.8; P = .03) among the YAG laser group. Best-corrected visual acuity changed by -0.2 letters in the YAG laser group and by -0.6 letters in sham group (difference, 0.4; 95% CI, -6.5 to 5.3; P = .94). No differences in adverse events between groups were identified. YAG laser vitreolysis subjectively improved Weiss ring-related symptoms and objectively improved Weiss ring appearance. Greater confidence in these outcomes may result from larger confirmatory studies of longer duration. clinicaltrials.gov NCT02897583.

Visual System Neural Responses to Laser Exposure from Local Q-Switched Pulses and Extended Source CW Speckle Patterns.

DTIC Science & Technology

1985-09-30

layers of the retina as seen in retinitis pigmentosa (Wolbarsht & Landers, 1980; Stefansson et al, 1981 a). Those are all long-term effects with a delay...block numoer) FIELD GROUP SUB-GROUP retinal damage center-surround 20 05 laser injury cat retina 20 06 visual perception N02 anesthesia 19. ABSTRACT...Continue on reverse if necessary and identify by block number) The reports of retinal damage from exposure to short pulse laser energy without any

Engine flow visualization using a copper vapor laser

NASA Technical Reports Server (NTRS)

Regan, Carolyn A.; Chun, Kue S.; Schock, Harold J., Jr.

1987-01-01

A flow visualization system has been developed to determine the air flow within the combustion chamber of a motored, axisymmetric engine. The engine has been equipped with a transparent quartz cylinder, allowing complete optical access to the chamber. A 40-Watt copper vapor laser is used as the light source. Its beam is focused down to a sheet approximately 1 mm thick. The light plane is passed through the combustion chamber, and illuminates oil particles which were entrained in the intake air. The light scattered off of the particles is recorded by a high speed rotating prism movie camera. A movie is then made showing the air flow within the combustion chamber for an entire four-stroke engine cycle. The system is synchronized so that a pulse generated by the camera triggers the laser's thyratron. The camera is run at 5,000 frames per second; the trigger drives one laser pulse per frame. This paper describes the optics used in the flow visualization system, the synchronization circuit, and presents results obtained from the movie. This is believed to be the first published study showing a planar observation of airflow in a four-stroke piston-cylinder assembly. These flow visualization results have been used to interpret flow velocity measurements previously obtained with a laser Doppler velocimetry system.

Ablation of dentin by irradiation of violet diode laser

NASA Astrophysics Data System (ADS)

Hatayama, H.; Kato, J.; Akashi, G.; Hirai, Y.; Inoue, A.

2006-02-01

Several lasers have been used for clinical treatment in dentistry. Among them, diode lasers are attractive because of their compactness compared with other laser sources. Near-infrared diode lasers have been practically used for cutting soft tissues. Because they penetrate deep to soft tissues, they cause sufficiently thick coagulation layer. However, they aren't suitable for removal of carious dentin because absorption by components in dentin is low. Recently, a violet diode laser with a wavelength of 405nm has been developed. It will be effective for cavity preparation because dentin contains about 20% of collagen whose absorption coefficient at a violet wavelength is larger than that at a near-infrared wavelength. In this paper, we examined cutting performance of the violet diode laser for dentin. To our knowledge, there have been no previous reports on application of a violet laser to dentin ablation. Bovine teeth were irradiated by continuous wave violet diode laser with output powers in a range from 0.4W to 2.4W. The beam diameter on the sample was about 270μm and an irradiation time was one second. We obtained the crater ablated at more than an output power of 0.8W. The depth of crater ranged from 20μm at 0.8W to 90μm at 2.4W. Furthermore, the beam spot with an output power of 1.7W was scanned at a speed of 1mm/second corresponding to movement of a dentist's hand in clinical treatment. Grooves with the depth of more than 50μm were also obtained. From these findings, the violet diode laser has good potential for cavity preparation. Therefore, the violet diode laser may become an effective tool for cavity preparation.

A non-contact temperature measurement system for controlling photothermal medical laser treatments

NASA Astrophysics Data System (ADS)

Kaya, Ã.-zgür; Gülsoy, Murat

2016-03-01

Photothermal medical laser treatments are extremely dependent on the generated tissue temperature. It is necessary to reach a certain temperature threshold to achieve successful results, whereas preventing to exceed an upper temperature value is required to avoid thermal damage. One method to overcome this problem is to use previously conducted dosimetry studies as a reference. Nevertheless, these results are acquired in controlled environments using uniform subjects. In the clinical environment, the optical and thermal characteristics (tissue color, composition and hydration level) vary dramatically among different patients. Therefore, the most reliable solution is to use a closed-loop feedback system that monitors the target tissue temperature to control laser exposure. In this study, we present a compact, non-contact temperature measurement system for the control of photothermal medical laser applications that is cost-efficient and simple to use. The temperature measurement is achieved using a focused, commercially available MOEMS infrared thermocouple sensor embedded in an off-axis arrangement on the laser beam delivery hand probe. The spot size of the temperature sensor is ca. 2.5 mm, reasonably smaller than the laser spot sizes used in photothermal medical laser applications. The temperature readout and laser control is realized using a microcontroller for fast operation. The utilization of the developed system may enable the adaptation of several medical laser treatments that are currently conducted only in controlled laboratory environments into the clinic. Laser tissue welding and cartilage reshaping are two of the techniques that are limited to laboratory research at the moment. This system will also ensure the safety and success of laser treatments aiming hyperthermia, coagulation and ablation, as well as LLLT and PDT.

Controlled feasibility trial comparing the use of 1470nm and 940nm diode laser for the treatment of hyperplastic inferior nasal turbinates

NASA Astrophysics Data System (ADS)

Sroka, Ronald; Havel, Miriam; Leunig, Andreas; Betz, Christian S.

2012-02-01

Introduction: So far various laser systems have been used for volume reduction of hyperplastic nasal turbinates. In case of endonasal application, fiber controlled diode lasers are preferred due to reasons of cost and practicability. The aim of this clinical study was to compare the coagulative tissue effects using either λ=1470nm vs. λ=940nm emitting lasers in treatment of hyperplastic inferior nasal turbinates in an intraindividual manner. Patients and methods: This prospective, randomized, double-blind, clinical feasibility trial included 20 patients suffering from hyperplastic inferior nasal turbinates. In each case, one nasal cavity was treated using 1470nm laser at 4- 5W, the other one with 940nm laser at 12W. Treatment was performed endoscopically controlled in non-contact mode. Clinical presentation and patients symptoms were documented preoperatively and on day 1, 3, 7, 14 and 21 postoperatively using rhinomanometry, standardized questionnaires including SNOT 20 GAV (German adapted version), and separate endoscopic examination respectively. Results: None of the patients showed infections, hemorrhages or other complications occurred intra- or postoperatively. The mean operation time was significantly shorter using the 1470nm diode laser as compared to the 940nm laser, thus lower energy was applied. There was a significant reduction of nasal obstruction on day 21 postoperatively compared to the preoperative condition on both sides regardless of the laser system used. Evaluation of the SNOT-Scores as assessed before and three weeks after surgery showed significant subjective improvements. Conclusion: Compared with standard application of 940nm diode laser, 1470nm diode laser application provides an equivalent tissue reduction in shorter operation time using less total energy and a comparable relief of nasal obstruction postoperatively.

Nd:YAG laser-induced morphology change and photothermal conversion of gold nanorods with potential application in the treatment of port-wine stain.

PubMed

Xing, Linzhuang; Chen, Bin; Li, Dong; Ma, Jun; Wu, Wenjuan; Wang, Guoxiang

2017-04-01

Based on the principle of selective photothermolysis, 1064 nm Nd:YAG laser has great potential for the treatment of deeper and larger PWS. However, the clinical effectiveness is limited because of the weak absorption of blood to Nd:YAG laser. The aim of this study is to obtain the optimal irradiation conditions to effectively destroy vascular lesions with the assistance of PEG-modified gold NRs to enhance blood absorption of Nd:YAG laser. In our study, PEG-modified gold NRs were prepared by the seeded growth method. Gold NRs after exposure to Nd:YAG laser were characterized using absorption spectra and transmission electron microscope images. The tissue-like phantom containing a glass capillary with blood was prepared and exposed to Nd:YAG laser to investigate the laser energy density and pulse number required for blood coagulation before and after the addition of gold NRs in blood. The results show that the millisecond Nd:YAG laser irradiation does not result in the shape change of gold NRs. After injection of gold NRs into the bloodstream (4.60 mg/kg), the absorbance of blood at 1064 nm increased 3.9 times. The threshold energy density for the treatment of PWS decreased by 33% (from 30 to 20 J/cm 2 ). Our findings provide an experimental guide for choosing laser parameters and gold NRs concentration for the treatment of deeper and larger PWS with the assistance of PEG-modified gold NRs in vivo in the future.

The application of diode laser in the treatment of oral soft tissues lesions. A literature review.

PubMed

Ortega-Concepción, Daniel; Cano-Durán, Jorge A; Peña-Cardelles, Juan-Francisco; Paredes-Rodríguez, Víctor-Manuel; González-Serrano, José; López-Quiles, Juan

2017-07-01

Since its appearance in the dental area, the laser has become a treatment of choice in the removal of lesions in the oral soft tissues, due to the numerous advantages they offer, being one of the most used currently the diode laser. The aim of this review was to determine the efficacy and predictability of diode laser as a treatment of soft tissue injuries compared to other surgical methods. A literature review of articles published in PubMed/MEDLINE, Scopus and the Cochrane Library databases between 2007 and 2017 was performed. "Diode laser", "soft tissue", "oral cavity" and "oral surgery" were employed for the search strategy. Only articles published English or Spanish were selected. The diode laser is a minimally invasive technology that offers great advantages, superior to those of the conventional scalpel, such as reduction of bleeding, inflammation and the lower probability of scars. Its effectiveness is comparable to that of other types of lasers, in addition to being an option of lower cost and greater ease of use. Its application in the soft tissues has been evaluated, being a safe and effective method for the excision of lesions like fibromas, epulis fissuratum and the accomplishment of frenectomies. The diode laser can be used with very good results for the removal of lesions in soft tissues, being used in small exophytic lesions due to their easy application, adequate coagulation, no need to suture and the slightest inflammation and pain. Key words: Diode laser, soft tissues, oral cavity, oral surgery.

Arthroscopic contact Nd:YAG laser meniscectomy: basic science, surgical technique, and clinical follow up

NASA Astrophysics Data System (ADS)

O'Brien, Stephen J.; Fealy, Stephen V.; Gibney, Mary A.; Miller, Drew V.; Kelly, Anne M.

1990-06-01

Recent basic science studies (5) have provided a scientific foundation for the use of the Contact Nd:YAG Laser as an arthroscopic tool for xneniscal resection and acroxnioplasty of the shoulder in a saline medium. This study prospectively evaluates the results of a three stage laboratory investigation as well as the clinical results of arthroscopic xneniscal resection. Fifteen patients with meniscal tears underwent subtotal meniscectomies utilizing a Contact Nd:YAG Laser (Surgical Laser Technologies; Malvern, Pennsylvania) . This was done in a saline medium with an average laser wattage of 25 W, (range 20 W to 30 W). Patients were evaluated postoperatively with reference to subjective and objective parameters at one week and four weeks postoperatively. Patients were evaluated with regard to wound healing, intraarticular swelling and pain. Assessment of technical parameters such as ease of resection, time of resection and instrument access were compared to conventional instruments. All fifteen patients were rated as having clinically excellent results based on pain relief, wound healing and swelling. In addition, although there was increased time with setting up the laser and calibrating it, there was not an increase in time for meniscal resection. Little, or no, secondary "trimmuning" was necessary with the laser. Increased accessibility was noted due to the small size of the laser. Arthroscopic Contact Nd:YAG Laser surgery is a safe and effective tool for menisca]. resection and coagulation in arthroscopic acromioplasties. It provides significant advantages over conventional cutting instruments with regard to accessibility and reduced need for secondary instruments.

Automatic temperature controlled retinal photocoagulation

NASA Astrophysics Data System (ADS)

Schlott, Kerstin; Koinzer, Stefan; Ptaszynski, Lars; Bever, Marco; Baade, Alex; Roider, Johann; Birngruber, Reginald; Brinkmann, Ralf

2012-06-01

Laser coagulation is a treatment method for many retinal diseases. Due to variations in fundus pigmentation and light scattering inside the eye globe, different lesion strengths are often achieved. The aim of this work is to realize an automatic feedback algorithm to generate desired lesion strengths by controlling the retinal temperature increase with the irradiation time. Optoacoustics afford non-invasive retinal temperature monitoring during laser treatment. A 75 ns/523 nm Q-switched Nd:YLF laser was used to excite the temperature-dependent pressure amplitudes, which were detected at the cornea by an ultrasonic transducer embedded in a contact lens. A 532 nm continuous wave Nd:YAG laser served for photocoagulation. The ED50 temperatures, for which the probability of ophthalmoscopically visible lesions after one hour in vivo in rabbits was 50%, varied from 63°C for 20 ms to 49°C for 400 ms. Arrhenius parameters were extracted as ΔE=273 J mol-1 and A=3.1044 s-1. Control algorithms for mild and strong lesions were developed, which led to average lesion diameters of 162+/-34 μm and 189+/-34 μm, respectively. It could be demonstrated that the sizes of the automatically controlled lesions were widely independent of the treatment laser power and the retinal pigmentation.

Laser-assisted treatment of patients with hemorrhagic diathesis

NASA Astrophysics Data System (ADS)

Neckel, Claus P.

2000-03-01

Today more and more patients with bleeding disorder come to our office for treatment. The number of patients with therapeutic anticoagulation is growing steadily. Discontinuation of this therapy can often be crucial. On the other hand are oralsurgical procedures extremely sensitive to bleeding due to the constant presents of saliva with its high fibrinolytic activity. The aim of this study was to evaluate the use of a surgical diode (wavelength 810 nm) laser as accessory tool in the treatment of patients with hemorrhagic diathesis. Enclosed in the study were 123 patients with: (1) Coumarintherapy, a Quick test ratio of 15 - 25%; (2) More than 300 mg of ASS/die; (3) Hemophilia, a factor activity under 35%; (4) Morbus Werlhof with less than 30000 thrombocytes. 179 Surgical procedures: (1) Tooth extraction 86%; (2) Apexectomy 3%; (3) Tumorexcision 9%; (4) Curettage and flapsurgery 1%; (5) Gingivectomy 1%. All procedures were laser-assisted with a diode laser emitting 810 nm. The glass fibers used were depending on the procedures either 200, 400, or 600 micron. No coagulating agents or tissue adhesives were used in addition. The postoperative outcome and complication rates were compared to substitution therapy and tissue adhesives. Laser-assisted treatment of these patients shows a high predictability and success rate leaving out side effects of drugs and human cryoprecipitates. Postoperative impairment is diminished.

Extensive tissue damage of bovine ovaries after bipolar ovarian drilling compared to monopolar electrocoagulation or carbon dioxide laser.

PubMed

Hendriks, Marja-Liisa; van der Valk, Paul; Lambalk, Cornelis B; Broeckaert, Mark A M; Homburg, Roy; Hompes, Peter G A

2010-02-01

To evaluate the size of ovarian damage caused by ovarian drilling in polycystic ovary syndrome, the amount of inflicted damage was assessed for the most frequently used ovarian drilling techniques. Experimental prospective design. University clinic. Six fresh bovine ovaries per technique. Carbon dioxide (CO(2)) laser, monopolar electrocoagulation, and bipolar electrocoagulation were used for in vitro ovarian drilling. Amount of inflicted ovarian damage per procedure. Bipolar electrocoagulation resulted in significantly more destruction per burn than the CO(2) laser and monopolar electrocoagulation (287.6 versus 24.0 and 70.0 mm(3), respectively). The damage found per lesion was multiplied by the regularly applied number of punctures per procedure in daily practice (based on the literature). Again, the bipolar electrocoagulation resulted in significantly more tissue damage than the CO(2) laser and monopolar coagulation (2,876 versus 599 and 700 mm(3), respectively). Ovarian drilling, especially bipolar electrocoagulation, causes extensive destruction of the ovary. Given the same clinical effectiveness of the various procedures, it is essential to use the lowest possible dose that works; thus, the first choice should be CO(2) laser or monopolar electrocoagulation. Copyright 2010 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Pulsed and CW adjustable 1942 nm single-mode all-fiber Tm-doped fiber laser system for surgical laser soft tissue ablation applications.

PubMed

Huang, Yize; Jivraj, Jamil; Zhou, Jiaqi; Ramjist, Joel; Wong, Ronnie; Gu, Xijia; Yang, Victor X D

2016-07-25

A surgical laser soft tissue ablation system based on an adjustable 1942 nm single-mode all-fiber Tm-doped fiber laser operating in pulsed or CW mode with nitrogen assistance is demonstrated. Ex vivo ablation on soft tissue targets such as muscle (chicken breast) and spinal cord (porcine) with intact dura are performed at different ablation conditions to examine the relationship between the system parameters and ablation outcomes. The maximum laser average power is 14.4 W, and its maximum peak power is 133.1 W with 21.3 μJ pulse energy. The maximum CW power density is 2.33 × 10⁶ W/cm² and the maximum pulsed peak power density is 2.16 × 10⁷ W/cm². The system parameters examined include the average laser power in CW or pulsed operation mode, gain-switching frequency, total ablation exposure time, and the input gas flow rate. The ablation effects were measured by microscopy and optical coherence tomography (OCT) to evaluate the ablation depth, superficial heat-affected zone diameter (HAZD) and charring diameter (CD). Our results conclude that the system parameters can be tailored to meet different clinical requirements such as ablation for soft tissue cutting or thermal coagulation for future applications of hemostasis.

The mechanism of tissue welding using a green laser: revisited

NASA Astrophysics Data System (ADS)

Richter, C.-P.; Bellam, R.; Hezarkhani, E.; Fiebig, T.

2017-02-01

A "green" laser (e.g. Nd:YAG, λ = 532 nm) together with the red dye Rose Bengal (RB) have been used for photochemical tissue bonding (PTB). It has been reported that irradiation of RB with light at 532 nm produces free radicals. For tissue bonding with a Nd:YAG laser it has been proposed that the free radicals than crosslink the tissue collagen and lead to the closing of the surgical incisions. RB is also a red solution and it is possible that RB absorbs the photons delivered from the laser and converts them into heat with a measurable local temperature increase. It is possible that the mechanism for PTB is not only caused by free radical formation but also by a temperature increase in the tissue. In the present study we measured the local tissue temperature with a micro thermometer during irradiation with a Nd:YAG laser before and after RB was applied. For the present laser settings "tissue painting" with RB lead to a temperature increase resulting in tissue coagulation and charring. PTB was also studied for RB with a free radical scavenger, vitamin C. No significant difference in bonding strength was found for RB alone and for RB together with a free radical scavenger. In case no RB was applied no tissue bonding occurred. Bonding strength was quantified using the leakage seal test

Using the Freiburg Acuity and Contrast Test to measure visual performance in USAF personnel after PRK.

PubMed

Dennis, Richard J; Beer, Jeremy M A; Baldwin, J Bruce; Ivan, Douglas J; Lorusso, Frank J; Thompson, William T

2004-07-01

Photorefractive keratectomy (PRK) may be an alternative to spectacle and contact lens wear for United States Air Force (USAF) aircrew and may offer some distinct advantages in operational situations. However, any residual corneal haze or scar formation from PRK could exacerbate the disabling effects of a bright glare source on a complex visual task. The USAF recently completed a longitudinal clinical evaluation of the long-term effects of PRK on visual performance, including the experiment described herein. After baseline data were collected, 20 nonflying active duty USAF personnel underwent PRK. Visual performance was then measured at 6, 12, and 24 months after PRK. Visual acuity (VA) and contrast sensitivity (CS) data were collected by using the Freiburg Acuity and Contrast Test (FrACT), with the subject viewing half of the runs through a polycarbonate windscreen. Experimental runs were completed under 3 glare conditions: no glare source and with either a broadband or a green laser (532-nm) glare annulus (luminance approximately 6090 cd/m) surrounding the Landolt C stimulus. Systematic effects of PRK on VA relative to baseline were not identified. However, VA was almost 2 full Snellen lines worse with the laser glare source in place versus the broadband glare source. A significant drop-off was observed in CS performance after PRK under conditions of no glare and broadband glare; this was the case both with and without the windscreen. As with VA, laser glare disrupted CS performance significantly and more than broadband glare did. PRK does not appear to have affected VA, but the changes in CS might represent a true decline in visual performance. The greater disruptive effects from laser versus broadband glare may be a result of increased masking from coherent spatial noise (speckle) surrounding the laser stimulus.

A new approach using coagulation rate constant for evaluation of turbidity removal

NASA Astrophysics Data System (ADS)

Al-Sameraiy, Mukheled

2017-06-01

Coagulation-flocculation-sedimentation processes for treating three levels of bentonite synthetic turbid water using date seeds (DS) and alum (A) coagulants were investigated in the previous research work. In the current research, the same experimental results were used to adopt a new approach on a basis of using coagulation rate constant as an investigating parameter to identify optimum doses of these coagulants. Moreover, the performance of these coagulants to meet (WHO) turbidity standard was assessed by introducing a new evaluating criterion in terms of critical coagulation rate constant (kc). Coagulation rate constants (k2) were mathematically calculated in second order form of coagulation process for each coagulant. The maximum (k2) values corresponded to doses, which were obviously to be considered as optimum doses. The proposed criterion to assess the performance of coagulation process of these coagulants was based on the mathematical representation of (WHO) turbidity guidelines in second order form of coagulation process stated that (k2) for each coagulant should be ≥ (kc) for each level of synthetic turbid water. For all tested turbid water, DS coagulant could not satisfy it. While, A coagulant could satisfy it. The results obtained in the present research are exactly in agreement with the previous published results in terms of finding optimum doses for each coagulant and assessing their performances. On the whole, it is recommended considering coagulation rate constant to be a new approach as an indicator for investigating optimum doses and critical coagulation rate constant to be a new evaluating criterion to assess coagulants' performance.

1064-/1319-nm Nd:YAG laser in maxillofacial surgery

NASA Astrophysics Data System (ADS)

Smucler, Roman; Mazanek, Jiri

1998-01-01

Patients feel face destruction as the main problem of oncological treatment in maxillofacial area. Finding a compromise between radicality and esthetic point of view is always problematic. Original Czech 1064/1319 nm Nd:YAG laser--U.S. patient pending--is new precise tool which can give new possibilities. Two wavelengths--with different water absorption--give unique chance to control collateral tissue damage. We can combine vaporization, coagulation and hyperthermic therapy special for every part of face and for every tissue. Thanks to that we use this machine in primary treatment and in palliative therapy independently or in combination with classical knife excision. Thanks to the use of fiber we are able to bit not only superficial lesions but we have opportunity of deep hyperthermic therapy with different collateral penetration. After 20 months we can show interesting results.

Shear-induced integrin signaling in platelet phosphatidylserine exposure, microvesicle release and coagulation.

PubMed

Pang, Aiming; Cui, Yujie; Chen, Yunfeng; Cheng, Ni; Delaney, M Keegan; Gu, Minyi; Stojanovic-Terpo, Aleksandra; Zhu, Cheng; Du, Xiaoping

2018-05-31

It is currently unclear why agonist-stimulated platelets require shear force to efficiently externalize the procoagulant phospholipid phosphatidylserine (PS) and release PS-exposed microvesicles (MVs). We reveal that integrin outside-in signaling is an important mechanism for this requirement. PS exposure and MV release were inhibited in β 3 -/- platelets or by integrin antagonists. The impaired MV release and PS exposure in β 3 -/- platelets were rescued by expressing wild type β 3 but not a Gα 13 binding-deficient β 3 mutant (E 733 EE to AAA), which blocks outside-in signaling but not ligand binding. Inhibition of Gα 13 or Src also diminished agonist/shear-dependent PS exposure and MV release, further indicating a role for integrin outside-in signaling. PS exposure in activated platelets was induced by application of pulling force via an integrin ligand, which was abolished by inhibiting Gα 13 -integrin interaction, suggesting that GGα 13 -dependent transmission of mechanical signals by integrins induces PS exposure. Inhibition of Gα 13 delayed coagulation in vitro. Furthermore, inhibition or platelet-specific knockout of Gα 13 diminished laser-induced intravascular fibrin formation in arterioles in vivo. Thus, β 3 integrins serve as a shear sensor activating the Gα 13 -dependent outside-in signaling pathway to facilitate platelet procoagulant function. Pharmacological targeting of Gα 13 -integrin interaction prevents occlusive thrombosis in vivo by inhibiting both coagulation and platelet thrombus formation. Copyright © 2018 American Society of Hematology.

Treatment of deep underlying reticular veins by Nd:Yag laser and IPL source.

PubMed

Colaiuda, S; Colaiuda, F; Gasparotti, M

2000-10-01

The purpose of this paper is to estimate the efficacy of Nd:Yag laser and IPL combined action for the treatment of deep (up to 5 mm) and large (up to 3 mm in diameter) reticular varicosity of the lower extremity. A group of 38 subjects (2 male and 36 female) aged from 34 to 65 years were treated for deep reticular varicosity of the legs. All patients underwent various clinical analyses in order to evaluate and exclude pre-existing cardiovascular pathology, coagulation disorders as well as pathology due to saphena incontinence. Also, for the first three months they underwent ambulatory specialistic treatments at 21-days intertreatment interval. A reduction of venous network of 80-90% after 2 treatment sessions with Nd:Yag laser was obtained in 84% of subjects. Successive 3 treatment sessions with IPL have achieved complete vanishing of the treated venous network in 36 patients (95%). A combined action of Nd:Yag laser and IPL has demonstrated its particular efficacy in non-invasive treatment of deep and extensive reticolar varicosity of the lower extremity, considering also that it is well tolerated by patients and applicable in each single case on out patient basis.

Comparative study of two intraoral laser techniques for soft tissue surgery

NASA Astrophysics Data System (ADS)

Swick, Michael D.; Richter, Alexander

2003-06-01

Historically, 810nm has been the predominant wavelength used for intraoral surgery, when diode lasers have been discussed, due to their large numbers in the market place. The techniques used intraorally with the 810nm diode have been relatively similar in most cases. Low powers, 1 or 2 watts, using continuous wave, are employed. The purpose of this study is to compare the thermal damage of the technique of using continuous wave at low powers, to using higher powers with a pulse mode and water for coolant, with the 980nm diode wavelength. During the study the laser fiber was held immobile eliminating surgical manipulation as an error. The resultant histology proves, while the volume of vaporization dramatically increases, thus giving the clinician the ability to reduce the time for destructive conduction of excess heat for a given procedure, the amount of coagulation actually decreases in width and depth. As an added benefit charring, which has been implicated in delayed healing is virtually eliminated. This evidence, coupled with excellent clinical results, lends validity to the use of pulsed higher powers and water coolant for the 980nm diode laser.

The clinical study of percutaneous disc decompression of treating herniation of cervical disc with Nd:YAG laser

NASA Astrophysics Data System (ADS)

Zhang, Dianxue; Cheng, Hefu; Wang, Jindong

2005-07-01

Objective: The possibility of PLDD (percutaneous laser disc decompression) and an ideal non-operative method which is long everlasting effect for PLDD was investigated. Methods: 159 patients of Cervical Disc Herniation with PLDD were studied. All the herniated discs were irradiated with 10­15J/S Nd:YAG laser quantum through optical-fiber under the supervision of C-arm X-ray. Results: All the patients were followed and reexamined CT or MRI after one to six months of PLDD. The result of cured (67.92%), excellent (24.53%), moderation (5.66%), non-effect (1.88%) was got. The excellent rate was 88.24%. The effective rate was 97.65%. Non-effective rate was 2.35%. Conclusion: When irradiated with Nd:YAG laser, the nucleus pulposus was vapouring, charring and coagulating. The volume and inner-pressure of the disc decreased. So the symptoms and signs improved. The main value of this methods were micro-damage, non-operation, no bleeding, no bone injury, good therapy effect, quick recovery, lesser pain, safety and excellent long everlasting effect. It is an ideal non-operative method of treating PLDD.

Beam shaping for cosmetic hair removal

NASA Astrophysics Data System (ADS)

Lizotte, Todd E.; Tuttle, Tracie

2007-09-01

Beam shaping has the potential to provide comfort to people who require or seek laser based cosmetic skin procedures. Of immediate interest is the procedure of aesthetic hair removal. Hair removal is performed using a variety of wavelengths from 480 to 1200 nm by means of filtered Xenon flash lamps (pulsed light) or 810 nm diode lasers. These wavelengths are considered the most efficient means available for hair removal applications, but current systems use simple reflector designs and plane filter windows to direct the light to the surface being exposed. Laser hair removal is achieved when these wavelengths at sufficient energy levels are applied to the epidermis. The laser energy is absorbed by the melanin (pigment) in the hair and hair follicle which in turn is transformed into heat. This heat creates the coagulation process, which causes the removal of the hair and prevents growth of new hair [1]. This paper outlines a technique of beam shaping that can be applied to a non-contact based hair removal system. Several features of the beam shaping technique including beam uniformity and heat dispersion across its operational treatment area will be analyzed. A beam shaper design and its fundamental testing will be discussed in detail.

Laser-ultrasonic inspection of hybrid laser-arc welded HSLA-65 steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lévesque, D.; Rousseau, G.; Monchalin, J.-P.

2014-02-18

The hybrid laser-arc welding (HLAW) process is a relatively low heat input joining technology that combines the synergistic qualities of both the high energy density laser beam for deep penetration and the arc for wide fit-up gap tolerance. This process is especially suitable for the shipbuilding industry where thick-gauge section, long steel plates have been widely used in a butt joint configuration. In this study, preliminary exploration was carried out to detect and visualize the welding defects using laser ultrasonics combined with the synthetic aperture focusing technique (SAFT). Results obtained on 9.3 mm thick butt-welded HSLA-65 steel plates indicated thatmore » the laser-ultrasonic SAFT inspection technique can successfully detect and visualize the presence of porosity, lack of fusion and internal crack defects. This was further confirmed by X-ray digital radiography and metallography. The results obtained clearly show the potential of using the laser-ultrasonic technology for the automated inspection of hybrid laser-arc welds.« less

Laser-ultrasonic inspection of hybrid laser-arc welded HSLA-65 steel

NASA Astrophysics Data System (ADS)

Lévesque, D.; Rousseau, G.; Wanjara, P.; Cao, X.; Monchalin, J.-P.

2014-02-01

The hybrid laser-arc welding (HLAW) process is a relatively low heat input joining technology that combines the synergistic qualities of both the high energy density laser beam for deep penetration and the arc for wide fit-up gap tolerance. This process is especially suitable for the shipbuilding industry where thick-gauge section, long steel plates have been widely used in a butt joint configuration. In this study, preliminary exploration was carried out to detect and visualize the welding defects using laser ultrasonics combined with the synthetic aperture focusing technique (SAFT). Results obtained on 9.3 mm thick butt-welded HSLA-65 steel plates indicated that the laser-ultrasonic SAFT inspection technique can successfully detect and visualize the presence of porosity, lack of fusion and internal crack defects. This was further confirmed by X-ray digital radiography and metallography. The results obtained clearly show the potential of using the laser-ultrasonic technology for the automated inspection of hybrid laser-arc welds.

Visual outcome of laser treatment in diabetic macular edema: Study from an Urban Diabetes Care Center.

PubMed

Alvi, Rashid; Memon, Muhammad Saleh; Shera, Samad; Mumtaz, Seema N; Shaikh, Sikander Ali; Fahim, Muhammad Faisal

2016-01-01

To determine the visual outcome of laser treatment in clinically significant macular edema. This interventional and qausi experimental study was carried out at Diabetic Association of Pakistan (DAP) during January 2011 and December 2012. Approval was taken from Research Ethical Committee of Isra Postgraduate Institute of Ophthalmology. Records of 925 eyes of 464 patients with "Clinical Significant macular edema" (CSME), treated with laser photocoagulation were analyzed. Best-corrected visual acuity (BCVA) at the time of presentation and at the last follow up, minimum of one year and maximum of 45 months was recorded and compared. SPSS version 20.0 was used to analyze the data. Diabetic retinopathy was found in 20.3% (1777) of 8742 diabetic attending DAP Hospital" amongst whom 39.6% (705) had Sight threatening diabetic retinopathy. Laser was advised in 96.4% (680) individuals, accepted by 70.5% (480) individuals. Amongst 960 eyes of 480 patients who accepted laser, 925 eyes had clinically significant macular edema and 35 eyes had PDR who are not included in this study. Amongst 925 eyes with CSME, Grid laser was done in 913 eyes (99%) and focal laser was done in 12 eyes (1%). After a follow up of 12 to 45 months, it was found that best corrected visual acuity had declined in 2.4% (22) eyes, stabilized in 67% (619) eyes and improved in 30.7% (284) eyes. One line improvement on Snellen's chart was fond in 21.3% (197) eyes, 2 lines in 8% (74) eyes, 3 lines in 1.2% (12) eyes and 4 lines in one (0.1%) eye with p-value of 0.000. Laser therapy is an effective treatment in stabilizing/improving the vision in diabetic macular edema particularly at those centers where only Argon Laser is available and OCF, FFA facilities do not exist.

Visual outcome of laser treatment in diabetic macular edema: Study from an Urban Diabetes Care Center

PubMed Central

Alvi, Rashid; Memon, Muhammad Saleh; Shera, Samad; Mumtaz, Seema N.; Shaikh, Sikander Ali; Fahim, Muhammad Faisal

2016-01-01

Objective: To determine the visual outcome of laser treatment in clinically significant macular edema. Methods: This interventional and qausi experimental study was carried out at Diabetic Association of Pakistan (DAP) during January 2011 and December 2012. Approval was taken from Research Ethical Committee of Isra Postgraduate Institute of Ophthalmology. Records of 925 eyes of 464 patients with “Clinical Significant macular edema” (CSME), treated with laser photocoagulation were analyzed. Best-corrected visual acuity (BCVA) at the time of presentation and at the last follow up, minimum of one year and maximum of 45 months was recorded and compared. SPSS version 20.0 was used to analyze the data. Results: Diabetic retinopathy was found in 20.3% (1777) of 8742 diabetic attending DAP Hospital” amongst whom 39.6% (705) had Sight threatening diabetic retinopathy. Laser was advised in 96.4% (680) individuals, accepted by 70.5% (480) individuals. Amongst 960 eyes of 480 patients who accepted laser, 925 eyes had clinically significant macular edema and 35 eyes had PDR who are not included in this study. Amongst 925 eyes with CSME, Grid laser was done in 913 eyes (99%) and focal laser was done in 12 eyes (1%). After a follow up of 12 to 45 months, it was found that best corrected visual acuity had declined in 2.4% (22) eyes, stabilized in 67% (619) eyes and improved in 30.7% (284) eyes. One line improvement on Snellen’s chart was fond in 21.3% (197) eyes, 2 lines in 8% (74) eyes, 3 lines in 1.2% (12) eyes and 4 lines in one (0.1%) eye with p-value of 0.000. Conclusion: Laser therapy is an effective treatment in stabilizing/improving the vision in diabetic macular edema particularly at those centers where only Argon Laser is available and OCF, FFA facilities do not exist. PMID:27882027

Infrared laser sealing of porcine vascular tissues using a 1,470 nm diode laser: Preliminary in vivo studies.

PubMed

Cilip, Christopher M; Kerr, Duane; Latimer, Cassandra A; Rosenbury, Sarah B; Giglio, Nicholas C; Hutchens, Thomas C; Nau, William H; Fried, Nathaniel M

2017-04-01

Infrared (IR) lasers are being explored as an alternative to radiofrequency (RF) and ultrasonic (US) devices for rapid hemostasis with minimal collateral zones of thermal damage and tissue necrosis. Previously, a 1,470 nm IR laser sealed and cut ex vivo porcine renal arteries of 1-8 mm diameter in 2 seconds, yielding burst pressures greater than 1,200 mmHg and thermal coagulation zones less than 3 mm. This preliminary study describes in vivo testing of a handheld laser probe in a porcine model. A handheld prototype with vessel/tissue clasping mechanism was tested on 73 blood vessels less than 6 mm diameter using 1,470 nm laser power of 35 W for 1-5 seconds. Device power settings, irradiation time, tissue type, vessel diameter, and histology sample number were recorded for each procedure. The probe was evaluated for hemostasis after sealing isolated and bundled arteriole/venous (A/V) vasculature of porcine abdomen and hind leg. Sealed vessel samples were collected for histological analysis of lateral thermal damage. Hemostasis was achieved in 57 of 73 seals (78%). The probe consistently sealed vasculature in small bowel mesentery, mesometrium, and gastrosplenic and epiploic regions. Seal performance was less consistent on hind leg vasculature including saphenous arteries/bundles and femoral and iliac arteries. Collagen denaturation averaged 1.6 ± 0.9 mm in eight samples excised for histologic examination. A handheld laser probe sealed porcine vessels, in vivo. Further probe development and laser parameter optimization is necessary before infrared lasers may be evaluated as an alternative to RF and US vessel sealing devices. Lasers Surg. Med. 49:366-371, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Efficacy of Punch Elevation Combined with Fractional Carbon Dioxide Laser Resurfacing in Facial Atrophic Acne Scarring: A Randomized Split-face Clinical Study

PubMed Central

Faghihi, Gita; Nouraei, Saeid; Asilian, Ali; Keyvan, Shima; Abtahi-Naeini, Bahareh; Rakhshanpour, Mehrdad; Nilforoushzadeh, Mohammad Ali; Hosseini, Sayed Mohsen

2015-01-01

Background: A number of treatments for reducing the appearance of acne scars are available, but general guidelines for optimizing acne scar treatment do not exist. The aim of this study was to compare the clinical effectiveness and side effects of fractional carbon dioxide (CO2) laser resurfacing combined with punch elevation with fractional CO2 laser resurfacing alone in the treatment of atrophic acne scars. Materials and Methods: Forty-two Iranian subjects (age range 18–55) with Fitzpatrick skin types III to IV and moderate to severe atrophic acne scars on both cheeks received randomized split-face treatments: One side received fractional CO2 laser treatment and the other received one session of punch elevation combined with two sessions of laser fractional CO2 laser treatment, separated by an interval of 1 month. Two dermatologists independently evaluated improvement in acne scars 4 and 16 weeks after the last treatment. Side effects were also recorded after each treatment. Results: The mean ± SD age of patients was 23.4 ± 2.6 years. Clinical improvement of facial acne scarring was assessed by two dermatologists blinded to treatment conditions. No significant difference in evaluation was observed 1 month after treatment (P = 0.56). Their evaluation found that fractional CO2 laser treatment combined with punch elevation had greater efficacy than that with fractional CO2 laser treatment alone, assessed 4 months after treatment (P = 0.02). Among all side effects, coagulated crust formation and pruritus at day 3 after fractional CO2 laser treatment was significant on both treatment sides (P < 0.05). Conclusion: Concurrent use of fractional laser skin resurfacing with punch elevation offers a safe and effective approach for the treatment of acne scarring. PMID:26538695

Laser robotically assisted nerve-sparing radical prostatectomy: a pilot study of technical feasibility in the canine model.

PubMed

Gianduzzo, Troy; Colombo, Jose R; Haber, Georges-Pascal; Hafron, Jason; Magi-Galluzzi, Cristina; Aron, Monish; Gill, Inderbir S; Kaouk, Jihad H

2008-08-05

To examine the feasibility of using laser energy during nerve-sparing robotically assisted radical prostatectomy (RARP), as the energy sources currently used for haemostasis in RARP adversely affect cavernous nerve function, while clips require application by a skilled assistant, but laser energy potentially allows precise dissection with minimal collateral tissue injury. We used laser-based RARP in 10 dogs, using the da Vinci S system (Intuitive Surgical, Sunnyvale, CA, USA) and a prototype robotic laser instrument. The potassium-titanyl-phosphate laser was used for dissection at 2-6 W, with intermittent use of the neodymium-doped yttrium-aluminium-garnet laser at 5 W for coagulating larger vessels. The peak intracavernosal pressure response to nerve stimulation was recorded as a percentage of mean arterial pressure (ICP%MAP) before and after RARP. Five dogs were killed immediately after RARP and five were maintained alive for 72 h; the haemoglobin and haematocrit levels were measured before and after RARP in the latter five dogs. All 10 procedures were performed solely using laser energy and no additional haemostatic manoeuvres. The median prostate excision time was 65 min. The ICP%MAP before and after RARP (median 98.5% and 77.0%, P = 0.12) were not significantly different; similarly, the respective haemoglobin (median 14.4 vs 12.6 g/dL, P = 0.06) and haematocrit levels (45.1% vs 40.2%, P = 0.06) were not significantly different. Two dogs had catheter-related complications and one had an anastomotic leak. There were no laser-related complications or postoperative haemorrhage. Laser RARP is feasible in dogs and further assessment is warranted.

Feasibility of MRI-guided Focused Ultrasound as Organ-Sparing Treatment for Testicular Cancer

NASA Astrophysics Data System (ADS)

Staruch, Robert; Curiel, Laura; Chopra, Rajiv; Hynynen, Kullervo

2009-04-01

High cure rates for testicular cancer have prompted interest in organ-sparing surgery for patients with bilateral disease or single testis. Focused ultrasound (FUS) ablation could offer a noninvasive approach to organ-sparing surgery. The objective of this study was to determine the feasibility of using MR thermometry to guide organ-sparing focused ultrasound surgery in the testis. The testes of anesthetized rabbits were sonicated in several discrete locations using a single-element focused transducer operating at 2.787MHz. Focal heating was visualized with MR thermometry, using a measured PRF thermal coefficient of -0.0089±0.0003 ppm/° C. Sonications at 3.5-14 acoustic watts applied for 30 seconds produced maximum temperature elevations of 10-80° C, with coagulation verified by histology. Coagulation of precise volumes in the testicle is feasible with MRI-guided focused ultrasound. Variability in peak temperature for given sonication parameters suggests the need for online temperature feedback control.

A novel fibrinogen variant--Praha I: hypofibrinogenemia associated with gamma Gly351Ser substitution.

PubMed

Kotlín, Roman; Chytilová, Martina; Suttnar, Jirí; Salaj, Peter; Riedel, Tomás; Santrůcek, Jirí; Klener, Pavel; Dyr, Jan Evangelista

2007-05-01

A 25-yr-old man from Prague had abnormal bleeding after several surgical operations with low fibrinogen level and hypofibrinogenemia was suspected. The patient, 25 yr-old male had a low fibrinogen concentration as determined by the thrombin time and immunoturbidimetrical method. His 48-yr-old mother presented with normal coagulation tests, normal fibrinogen level and reported no history of bleeding. To identify the genetic mutation responsible for this hypofibrinogen, genomic DNA extracted from the blood was analyzed. Fibrin polymerization measurement, kinetics of fibrinopeptide release, fibrinogen clottability measurement, mass spectroscopy, and scanning electron microscopy were performed. DNA sequencing showed heterogeneous fibrinogen gammaG351S mutation in the propositus. The mutant chain was found not to be expressed to the circulation by matrix-assisted laser desorption/ionization time of flight mass spectrometry. Scanning electron micrographs of the patient's fibrin clot as well as kinetics of fibrinopeptide release and fibrin polymerization were found to be normal. A case of hypofibrinogenemia gammaG351S was found by routine coagulation testing and was genetically identified.

Laser surgery and medicine including photodynamic therapy in China today

NASA Astrophysics Data System (ADS)

Li, Junheng

2000-10-01

The development of laser medicine in China is correlated with the development of laser science in China. After the first Chinese laser, ruby laser came into being in 1961, Chinese medical scientists began to do the studies about laser medicine in the middle 1960s. For example, ruby laser was adopted for the retina coagulation experiment in 1965. Since 1970s, through the free choice of utilizing Co2, He-Ne, Nd:YAG argon, ruby lasers, laser surgery and medicine has been widely applied to the treatment for diseases of the eyes, ENT, dermatology, surgery, gynecology, tumors and diseases suitable to physical therapy or acupuncture with satisfactory effects. In June 1977, a nation-wide laser medicine symposium was held at Wuhan, Hubei Province with 200 participants including medical doctors and laser technologies from 23 provinces and municipal towns. Till the end of seventies, utilization of lasers has been extended to Nd glass laser, N laser and tunable dye lasers. The scope covered most of the clinical sections. After Dr. Thomas J. Dougherty developed the PDT for cancers in Roswell Park Memorial Institute in Buffalo in late 1970s and Professor Yoshihiro Hayata successfully applied the PDT in clinical treatment for lung cancer in 1980, Chinese pharmacists successfully produced the Chinese HpD and the first case of PDT, a lower eyelid basal cell carcinoma patient was treated with the Chinese laser equipment in 1981 in Beijing. Its success brought attention establishing a research group supported by the government in 1982. The members of the group consisted the experts on preclinical and clinical research, pharmaceutical chemistry, laser physicists and technologists. A systemic research on PDT was then carried out and obvious result was achieved. The step taken for PDT also accelerated the researchers on other kinds of laser medicine and surgery because the medical doctors had begun to master the knowledge about laser science. The prosperous situation of rapid development of laser science, bio-medical lasers, laser medicine and surgery as well as PDT was prolonged in the whole nineteen eighties.

Rennet-induced coagulation properties of yak casein micelles: A comparison with cow casein micelles.

PubMed

Zhang, Yan; Li, Yuan; Wang, Pengjie; Tian, Yanbao; Liang, Qi; Ren, Fazheng

2017-12-01

It is essential for yak cheese processing to understand the rennet-induced coagulation properties of gel formation from casein micelles. We have previously discovered that yak milk requires a longer incubation time but forms stronger gels compared with cow milk. In this study, we are aiming to understand the rennet-induced coagulation properties of yak casein micelles comparing with cow casein micelles. Rheological analyses revealed that the gelling times of yak and cow casein micelles were 11.6±0.5 and 8.7±0.4min (P<0.05) respectively, but yak casein gel had a higher elastic modulus G' (6.5±0.2Pa) than cow casein gel (2.5±0.2Pa; P<0.05). This is consistent with the results obtained by micro-rheology. Confocal laser scanning microscopic images (CLSM) and cryo-scanning electron microscopic images (cryo-SEM) showed that yak casein gel was more homogeneous and had smaller pore size than cow casein gels. Yak casein micelles had higher calcium (26.00mM), phosphate (19.90mM) and β-casein (relative 32%) concentrations. In addition, yak casein micelles were larger (Z-average 218.6nm) than cow casein micelles, and contained lower κ-casein (relative 13%). By comparison with cow casein micelles, yak casein micelle composition corresponding to their micellar calcium phosphate and κ-casein content may greatly contribute to the longer coagulation time and denser gel structure. An initial slower caseinomacropeptide (CMP) release rate and the slower rate of aggregation between para-casein micelles contributed to a more homogeneous yak gel network. Higher colloidal calcium phosphate is crucial for yak casein micelle aggregation and gel firmness because sufficient colloidal calcium phosphates can firmly glue sub-micelles and links casein micelles. This study provides valuable information for yak cheese production. Copyright © 2017. Published by Elsevier Ltd.

Efficacy and perioperative timing of bromfenac in the management of ocular discomfort after femtosecond laser-assisted laser in situ keratomileusis.

PubMed

Cleaveland, Nathan A; De Mann, Derek W; Carlson, Neil E; Keil, Michael L

2017-02-01

To evaluate the safety, efficacy, and appropriate perioperative timing of the use of topical bromfenac ophthalmic solution 0.07% after femtosecond laser-assisted laser in situ keratomileusis (LASIK). Keil LASIK Vision Center, Grand Rapids, Michigan, USA. Prospective case series. Ocular discomfort was assessed 1, 2, and 5 hours postoperatively and the following morning using the Ocular Comfort Grading Assessment in patients treated with topical bromfenac 0.07% or artificial tears just before, just after, or before and after femtosecond laser-assisted LASIK. Visual outcomes and complications were noted up to 24 hours. The study enrolled 64 patients (120 eyes). Patients who were treated with bromfenac 0.07% just before or before and after femtosecond laser-assisted LASIK showed the greatest statistically significant decrease in several discomfort scores within the first few hours in comparison with the control group. Two hours after surgery, the majority of patients who were treated before and after LASIK were sleeping comfortably. There were no significant differences in visual acuity; 1 day postoperatively, the uncorrected distance visual acuity was 20/20 in 106 eyes (89%) and 20/25 or better in 116 eyes (97%). At 3 months, all patients had binocular distance visual acuity of 20/20 or better and 86% of patients had 20/15 or better. Ocular discomfort after femtosecond laser-assisted LASIK was reduced with a single dose of topical bromfenac 0.07% given immediately before surgery or given just before and after surgery and was typically minimal in all groups the morning after surgery. Copyright © 2017 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Photolasertherapy for the treatment of infections in neurosurgery: experimental and clinical study

NASA Astrophysics Data System (ADS)

Lombard, Gian F.

1996-12-01

At the first time, the CO2 laser was utilised in infective neurosurgical pathology as a surgical cutting instrument to remove inflammatory pseudomembranes in chronic osteomyelitis, and as a vaporising instmment on the dura mater surface. Successively, the instrument, defocused and at a low power, was used for prolonged and diffuse photo coagulation ofthe surgical cavity, particularly, ofthe dural surface and ofthe osteomyelitic bone edges, with the aim to sterilise tissues. So, we saw a shortening of the average time of wound healing and a lack of recurrence of the septic pathology. Then, we have treated, with CO2 laser, intracranial infective pathology: i.e. primary abscesses, capsulated or not, circumscribed purulent encephalitis, secondary abscesses in surgical cavities (patients operated for intracranial hematomas and tumors). In these cases we have obtained a lack of septic recurrences and an improvement ofneurological post-operative course. Thank to these results, we have continued to use laser in infective pathology; for giving an experimental support to these results we have carried on researches in vivo (on the experimental animal) to see the interaction between the laser and inflammatory tissue, and in vitro (on bacterial culture: in solid and liquid media) to see the laser effect on the bacterial cell. The bacterial cell has been also sensibiized to the photo dynamic effect of the laser (Argon, He-Ne), with hematoporphyrin. The goal of these experiments is to understand the role of thermal, photochemical, and mechanic resonance laser effects in the interaction between laser radiation and bacterial cell.

Initial clinical results of laser prostatectomy procedure for symptomatic BPH using a new 50-watt diode laser (wavelength 1000 nm)

NASA Astrophysics Data System (ADS)

Bhatta, Krishna M.

1995-05-01

Lasers have been used for symptomatic Benign Prostatic Hyperplasia (BPH) in both contact and non-contact modes with reported success rates equivalent to that of Transurethral Resection of Prostate (TURP). A new high power diode laser (Phototome), capable of delivering up to 50 watts of 1000 nm wavelength laser power via a 1 mm quartz fiber, was used to treat 15 patients with symptomatic BPH. Five patients had acute retention, 3 had long term catheter (7 - 48 months), and 8 had severe prostatism. Spinal anesthesia was used in 11 patients, and 4 patients had local anesthesia and intravenous sedation. Four quadrant coagulation with an angle firing probe delivering 50 watts of laser power for 60 seconds in one quadrant was used as the core of the treatment in 11 patients, contact vaporization of BPH tissue was performed in one patient using a 4.5 mm ball tip was used in one patient and three patients with bladder neck stenosis had bladder neck incision performed using a 1 mm quartz fiber delivering 30 watts of laser power. A foley catheter was left indwelling and removed after 5 - 7 days. All patients except one were catheter free after a mean of 8 days. One patient continued to have severe prostatism and had a TURP performed with good results after 3 months of his laser prostatectomy procedure. AUA symptom scores available in 11 patients was found to be 4 after 1 - 3 months of the initial procedure.

Long-pulsed 1064-nm neodymium:yttrium-aluminum-garnet laser treatment for refractory warts on hands and feet.

PubMed

Kimura, Utako; Takeuchi, Kaori; Kinoshita, Ayako; Takamori, Kenji; Suga, Yasushi

2014-03-01

Common warts (verruca vulgaris) are the most commonly seen benign cutaneous tumors. However, warts in the hands and feet regions often respond poorly to treatment, some are resistant to more than 6 months of treatment with currently available modalities, including cryotherapy, being defined as refractory warts. We investigated the usefulness of long-pulsed neodymium:yttrium-aluminum-garnet (LP-Nd:YAG) treatment for refractory warts. The clinical trial was conducted on 20 subjects (11 male, nine female) with a total of 34 lesions (periungual/subungual areas, plantar areas, fingers and/or toes). All the subjects suffered from refractory warts despite conventional treatments for more than 6 months. The patients were administrated up to six sessions of treatment, at intervals of 4 weeks between sessions, with an LP-Nd:YAG at a spot size of 5 mm, pulse duration of 15 msec and fluence of 150-185 J/cm(2) . Evaluation of the treatment results at 24 weeks after the initial treatment showed complete clearance of the refractory warts in 56% of the patients. Histological evaluation showed separation of the dermis and epidermis at the basement membrane with coagulated necrosis of the wart tissue in the lower epidermis, as well as coagulation and destruction of the blood vessels in the papillary dermis following the laser irradiation. No scarring, post-hyperpigmentary changes or serious adverse events were documented. Our preliminary results show that LP-Nd:YAG treatments are safe and effective for refractory warts of hands and feet, causing minimal discomfort, and is a viable treatment alternative. © 2014 Japanese Dermatological Association.

Noninvasive laser coagulation of the canine vas deferens, in vivo

NASA Astrophysics Data System (ADS)

Cilip, Christopher M.; Ross, Ashley E.; Jarow, Jonathan P.; Fried, Nathaniel M.

2010-02-01

Development of a noninvasive vasectomy technique may eliminate male fear of complications (incision, bleeding, infection, and scrotal pain) and result in a more popular procedure. This study builds upon previously reported ex vivo tissue studies by exploring acute and short-term chronic in vivo canine studies. Isolation of the canine vas was achieved using a conventional vas ring clamp method. No perforation of the scrotal skin was necessary to occlude the vas. Laser radiation with a wavelength of 1075 nm, average power of 11.2 W, 500-ms pulse duration, 0.5 Hz pulse rate, and 3-mm-diameter spot was synchronized with cryogen spray cooling of the scrotal skin surface in a total of 8 dogs (n = 16 vasa) for a treatment time of 60 s. Burst pressure measurements were conducted at Days 0 and 21 (n = 8 vasa each day) to quantify the strength of vas closure. The vas was successfully thermally occluded in 15/16 (94%) procedures with 14/15 (93%) vas recording burst pressures above ejaculation pressure. One vas was not present, and another vas recorded a bursting pressure below ejaculation pressure. The coagulated vas bursting pressure averaged 283 +/- 34 mm Hg at Day 0 and 260 +/- 77 mm Hg at Day 21, significantly higher than reported vas ejaculation pressures of 136 +/- 29 mm Hg. Minor scrotal skin burns were observed during the recovery period. Noninvasive thermal occlusion of the vas is feasible in an in vivo canine model. Elimination of minor skin burns and longer term chronic in vivo canine studies are needed to confirm azospermia after vas occlusion without recanalization.

Evaluation of diffuse-illumination holographic cinematography in a flutter cascade

NASA Technical Reports Server (NTRS)

Decker, A. J.

1986-01-01

Since 1979, the Lewis Research Center has examined holographic cinematography for three-dimensional flow visualization. The Nd:YAG lasers used were Q-switched, double-pulsed, and frequency-doubled, operating at 20 pulses per second. The primary subjects for flow visualization were the shock waves produced in two flutter cascades. Flow visualization was by diffuse-illumination, double-exposure, and holographic interferometry. The performances of the lasers, holography, and diffuse-illumination interferometry are evaluated in single-window wind tunnels. The fringe-contrast factor is used to evaluate the results. The effects of turbulence on shock-wave visualization in a transonic flow are discussed. The depth of field for visualization of a turbulent structure is demonstrated to be a measure of the relative density and scale of that structure. Other items discussed are the holographic emulsion, tests of coherence and polarization, effects of windows and diffusers, hologram bleaching, laser configurations, influence and handling of specular reflections, modes of fringe localization, noise sources, and coherence requirements as a function of the pulse energy. Holography and diffuse illumination interferometry are also reviewed.

Wireless ultrasonic wavefield imaging via laser for hidden damage detection inside a steel box girder bridge

NASA Astrophysics Data System (ADS)

An, Yun-Kyu; Song, Homin; Sohn, Hoon

2014-09-01

This paper presents a wireless ultrasonic wavefield imaging (WUWI) technique for detecting hidden damage inside a steel box girder bridge. The proposed technique allows (1) complete wireless excitation of piezoelectric transducers and noncontact sensing of the corresponding responses using laser beams, (2) autonomous damage visualization without comparing against baseline data previously accumulated from the pristine condition of a target structure and (3) robust damage diagnosis even for real structures with complex structural geometries. First, a new WUWI hardware system was developed by integrating optoelectronic-based signal transmitting and receiving devices and a scanning laser Doppler vibrometer. Next, a damage visualization algorithm, self-referencing f-k filter (SRF), was introduced to isolate and visualize only crack-induced ultrasonic modes from measured ultrasonic wavefield images. Finally, the performance of the proposed technique was validated through hidden crack visualization at a decommissioned Ramp-G Bridge in South Korea. The experimental results reveal that the proposed technique instantaneously detects and successfully visualizes hidden cracks even in the complex structure of a real bridge.

The Laser Level as an Optics Laboratory Tool

ERIC Educational Resources Information Center

Kutzner, Mickey

2013-01-01

For decades now, the laser has been used as a handy device for performing ray traces in geometrical optics demonstrations and laboratories. For many ray- trace applications, I have found the laser level 3 to be even more visually compelling and easy for student use than the laser pointer.

A Visualization Method for Corrosion Damage on Aluminum Plates Using an Nd:YAG Pulsed Laser Scanning System

PubMed Central

Lee, Inbok; Zhang, Aoqi; Lee, Changgil; Park, Seunghee

2016-01-01

This paper proposes a non-contact nondestructive evaluation (NDE) technique that uses laser-induced ultrasonic waves to visualize corrosion damage in aluminum alloy plate structures. The non-contact, pulsed-laser ultrasonic measurement system generates ultrasonic waves using a galvanometer-based Q-switched Nd:YAG laser and measures the ultrasonic waves using a piezoelectric (PZT) sensor. During scanning, a wavefield can be acquired by changing the excitation location of the laser point and measuring waves using the PZT sensor. The corrosion damage can be detected in the wavefield snapshots using the scattering characteristics of the waves that encounter corrosion. The structural damage is visualized by calculating the logarithmic values of the root mean square (RMS), with a weighting parameter to compensate for the attenuation caused by geometrical spreading and dispersion of the waves. An intact specimen is used to conduct a comparison with corrosion at different depths and sizes in other specimens. Both sides of the plate are scanned with the same scanning area to observe the effect of the location where corrosion has formed. The results show that the damage can be successfully visualized for almost all cases using the RMS-based functions, whether it formed on the front or back side. Also, the system is confirmed to have distinguished corroded areas at different depths. PMID:27999252

A Visualization Method for Corrosion Damage on Aluminum Plates Using an Nd:YAG Pulsed Laser Scanning System.

PubMed

Lee, Inbok; Zhang, Aoqi; Lee, Changgil; Park, Seunghee

2016-12-16

This paper proposes a non-contact nondestructive evaluation (NDE) technique that uses laser-induced ultrasonic waves to visualize corrosion damage in aluminum alloy plate structures. The non-contact, pulsed-laser ultrasonic measurement system generates ultrasonic waves using a galvanometer-based Q-switched Nd:YAG laser and measures the ultrasonic waves using a piezoelectric (PZT) sensor. During scanning, a wavefield can be acquired by changing the excitation location of the laser point and measuring waves using the PZT sensor. The corrosion damage can be detected in the wavefield snapshots using the scattering characteristics of the waves that encounter corrosion. The structural damage is visualized by calculating the logarithmic values of the root mean square (RMS), with a weighting parameter to compensate for the attenuation caused by geometrical spreading and dispersion of the waves. An intact specimen is used to conduct a comparison with corrosion at different depths and sizes in other specimens. Both sides of the plate are scanned with the same scanning area to observe the effect of the location where corrosion has formed. The results show that the damage can be successfully visualized for almost all cases using the RMS-based functions, whether it formed on the front or back side. Also, the system is confirmed to have distinguished corroded areas at different depths.

Linking pain and the body: neural correlates of visually induced analgesia.

PubMed

Longo, Matthew R; Iannetti, Gian Domenico; Mancini, Flavia; Driver, Jon; Haggard, Patrick

2012-02-22

The visual context of seeing the body can reduce the experience of acute pain, producing a multisensory analgesia. Here we investigated the neural correlates of this "visually induced analgesia" using fMRI. We induced acute pain with an infrared laser while human participants looked either at their stimulated right hand or at another object. Behavioral results confirmed the expected analgesic effect of seeing the body, while fMRI results revealed an associated reduction of laser-induced activity in ipsilateral primary somatosensory cortex (SI) and contralateral operculoinsular cortex during the visual context of seeing the body. We further identified two known cortical networks activated by sensory stimulation: (1) a set of brain areas consistently activated by painful stimuli (the so-called "pain matrix"), and (2) an extensive set of posterior brain areas activated by the visual perception of the body ("visual body network"). Connectivity analyses via psychophysiological interactions revealed that the visual context of seeing the body increased effective connectivity (i.e., functional coupling) between posterior parietal nodes of the visual body network and the purported pain matrix. Increased connectivity with these posterior parietal nodes was seen for several pain-related regions, including somatosensory area SII, anterior and posterior insula, and anterior cingulate cortex. These findings suggest that visually induced analgesia does not involve an overall reduction of the cortical response elicited by laser stimulation, but is consequent to the interplay between the brain's pain network and a posterior network for body perception, resulting in modulation of the experience of pain.

Utility and safety of a novel surgical microscope laser light source

PubMed Central

Bakhit, Mudathir S.; Suzuki, Kyouichi; Sakuma, Jun; Fujii, Masazumi; Murakami, Yuta; Ito, Yuhei; Sugano, Tetsuo; Saito, Kiyoshi

2018-01-01

Objective Tissue injuries caused by the thermal effects of xenon light microscopes have previously been reported. Due to this, the development of a safe microscope light source became a necessity. A newly developed laser light source is evaluated regarding its effectiveness and safety as an alternative to conventional xenon light source. Methods We developed and tested a new laser light source for surgical microscopes. Four experiments were conducted to compare xenon and laser lights: 1) visual luminance comparison, 2) luminous and light chromaticity measurements, 3) examination and analysis of visual fatigue, and 4) comparison of focal temperature elevation due to light source illumination using porcine muscle samples. Results Results revealed that the laser light could be used at a lower illumination value than the xenon light (p < 0.01). There was no significant difference in visual fatigue status between the laser light and the xenon light. The laser light was superior to the xenon light regarding luminous intensity and color chromaticity. The focal temperature elevation of the muscle samples was significantly higher when irradiated with xenon light in vitro than with laser light (p < 0.01). Conclusion The newly developed laser light source is more efficient and safer than a conventional xenon light source. It lacks harmful ultraviolet waves, has a longer lifespan, a lower focal temperature than that of other light sources, a wide range of brightness and color production, and improved safety for the user’s vision. Further clinical trials are necessary to validate the impact of this new light source on the patient’s outcome and prognosis. PMID:29390016

Enhancing the reproducibility of ocular vestibular evoked myogenic potentials by use of a visual target originating from a head-mounted laser.

PubMed

Jerin, Claudia; Bartl, Klaus; Schneider, Erich; Gürkov, Robert

2015-10-01

Ocular vestibular evoked myogenic potentials (oVEMPs) represent extraocular muscle activity in response to vestibular stimulation. oVEMP amplitudes are known to increase with increasing upward gaze angle, while the patient fixates a visual target. We investigated two different methods of presenting a visual target during oVEMP recordings. 57 healthy subjects were enrolled in this study. oVEMPs were elicited by 500 Hz air-conducted tone bursts while the subjects were looking upward at a marking which was either fixed on the wall or originated from a head-mounted laser attached to a headband, in either case corresponding to a 35° upward gaze angle. oVEMP amplitudes and latencies did not differ between the subjects looking at the fixed marking and the ones looking at the laser marking. The intra-individual standard deviation of amplitudes obtained by two separate measurements for each subject, however, as a measure of test-retest reliability, was significantly smaller for the laser headband group (0.60) in comparison to the group looking at the fixed marking (0.96; p = 0.007). The intraclass correlation coefficient revealed better test-retest reliability for oVEMP amplitudes when using the laser headband (0.957) than using the fixed marking (0.908). Hence, the use of a visual target originating from a headband enhances the reproducibility of oVEMPs. This might be due to the fact that the laser headband ensures a constant gaze angle and rules out the influence of small involuntary head movements on the gaze angle.

Visual outcome and refractive status in first 3 years of age in preterm infants suffered from laser-treated Type 1 retinopathy of prematurity (ROP): a 6-year retrospective review in a tertiary centre in Hong Kong.

PubMed

Lok, Julie Y C; Yip, Wilson W K; Luk, Abbie S W; Chin, Joyce K Y; Lau, Henry H W; Young, Alvin L

2018-02-01

To report the visual outcome and refractive status in first 3 years of age in preterm infants suffered from laser-treated Type 1 retinopathy of prematurity (ROP): a 6-year review in Hong Kong DESIGN: Retrospective case series METHODOLOGY: Clinical records of all infants suffered from Type 1 ROP who had undergone laser therapy between 2007 and 2012 were retrospectively reviewed. Basic demographic data, serial changes of refractive error, visual acuity, severity of ROP and laser were analyzed. Correlation with myopia and astigmatism progression, body weight, height, growth and gestational age were also analyzed. Among 494 babies screened, 14 Chinese babies (26 eyes) recruited with 1:1 male-to-female ratio in this study. All eyes showed gradual progression of myopia in first 3 years of age but no significant change of astigmatism. Further correlation analysis showed no correlation with laser energy consumed, birth weight (p = 0.14), head circumference growth (p = 0.57) and body weight growth (p = 0.71). However, severity of myopia was related to the post-conceptual age when receiving laser therapy (p < 0.005), gestation age (p = 0.02) and possibly body height growth with age (p = 0.05). Myopia in early life is one of the most common ocular sequelae in Type 1 ROP survivors. Early detection of refractive error is important for prompt correction and visual rehabilitation to prevent amblyopia.

Histological evaluation of vertical laser channels from ablative fractional resurfacing: an ex vivo pig skin model.

PubMed

Skovbølling Haak, Christina; Illes, Monica; Paasch, Uwe; Hædersdal, Merete

2011-07-01

Ablative fractional resurfacing (AFR) represents a new treatment potential for various skin conditions and new laser devices are being introduced. It is important to gain information about the impact of laser settings on the dimensions of the created laser channels for obtaining a safe and efficient treatment outcome. The aim of this study was to establish a standard model to document the histological tissue damage profiles after AFR and to test a new laser device at diverse settings. Ex vivo abdominal pig skin was treated with a MedArt 620, prototype fractional carbon dioxide (CO(2)) laser (Medart, Hvidovre, Denmark) delivering single microbeams (MB) with a spot size of 165 μm. By using a constant pulse duration of 2 ms, intensities of 1-18 W, single and 2-4 stacked pulses, energies were delivered in a range from 2-144 mJ/MB. Histological evaluations included 3-4 high-quality histological measurements for each laser setting (n = 28). AFR created cone-shaped laser channels. Ablation depths varied from reaching the superficial dermis (2 mJ, median 41 μm) to approaching the subcutaneous fat (144 mJ, median 1,943 μm) and correlated to the applied energy levels in an approximate linear relation (r(2) = 0.84, p < 0.001). The dermal ablation width increased slightly within the energy range of 4-144 mJ (median 163 μm). The thickness of the coagulation zone reached a plateau around 65 μm at energies levels above 16 mJ. The calculated volumes of ablated tissue increased with increasing energies. We suggest this ex vivo pig skin model to characterize AFR laser channels histologically.

Histological changes induced by CO2 laser microprobe specially designed for root canal sterilization: in vivo study.

PubMed

Kesler, G; Koren, R; Kesler, A; Hay, N; Gal, R

1998-10-01

Until now, no suitable delivery fiber has existed for CO2 laser endodontic radiation in the apical region, where it is most difficult to eliminate the pulp tissue using conventional methods. To overcome this problem, we have designed a microprobe that reaches closer to the apex, distributing the energy density to a smaller area of the root canal and thus favorably increasing the thermal effects. A CO2 laser microprobe coupled onto a special hand piece was attached to the delivery fiber of a Sharplan 15-F CO2 laser. The study was conducted on 30 vital maxillary or mandibulary, central, lateral, or premolar teeth destined for extraction due to periodontal problems. Twenty were experimentally treated with pulsed CO2 laser delivered by this newly developed fiber after conventional root canal preparation. Temperature measured at three points on the root surface during laser treatment did not exceed 38 degrees C. Ten teeth represented the control group, in which only root canal preparation was performed in the conventional method. Histological examination of the laser-treated teeth showed coagulation necrosis and vacuolization of the remaining pulp tissue in the root canal periphery. Primary and secondary dentin appeared normal in all cases treated with 15-F CO2 laser. Gram stain and bacteriologic examination revealed complete sterilization. These results demonstrate the unique capabilities of this special microprobe in sterilization of the root canal, with no thermal damage to the surrounding tissue. The combination of classical root canal preparation with CO2 laser irradiation using this special microprobe before closing the canal can drastically change the quality of root canal fillings.

Comparison of gingival depigmentation with Er,Cr:YSGG laser and surgical stripping, a 12-month follow-up.

PubMed

Gholami, Leila; Moghaddam, Somayeh Ansari; Rigi Ladiz, Mohammad Ayoub; Molai Manesh, Zohreh; Hashemzehi, Hadi; Fallah, Alireza; Gutknecht, Norbert

2018-04-13

Gingival melanin hyperpigmentation is an esthetic concern for many individuals. In this study, we compared the standard surgical removal method with two different Er,Cr:YSGG laser settings in order to find the best treatment method. In 33 dental arches, the following three treatment groups were comparatively evaluated: (1) surgical stripping, (2) removal with laser setting 1 (4.5 W, 50 Hz, 100% water, 80% air, 60 μs, 800 μm Tip; MZ8), and (3) laser setting 2 (2.5 W, 50 Hz, 20% water, 40% air, 700 μs, 800 μm Tip; MZ8). We comparatively evaluated pain, patient satisfaction and wound healing, treatment time, and the amount of bleeding. Re-pigmentation was evaluated after 1 and 12 months by Hedin and Dummet pigmentation scores. Laser setting 1 had the best results regarding pain and patient satisfaction, although not statistically significant (P > 0.05). Wound healing results were better using lasers compared to surgical stripping (P < 0.05). Laser setting 1 was a faster procedure with mild amounts of bleeding. The least amount of bleeding was seen with laser setting 2. After 1 month, only two cases of the laser setting 2-treated areas showed an isolated pigmented area in the papilla; at 12 months, the mean Hedin indexes were still less than 2 and mean Dummett index less than 1 in all treatment techniques, with the lowest scores seen in the laser setting 1 sites. Based on our results, Er,Cr:YSGG laser can be more convenient for gingival depigmentation compared to surgical blade. Although not statistically significant, laser setting 1 with shorter pulse duration and higher water spray showed better overall results. However, laser setting 2, with longer pulse duration and less water spray, resulted in better coagulative effects and can be used to control bleeding wherever necessary in clinical practice.

Investigation of multiple scattering effects in aerosols

NASA Technical Reports Server (NTRS)

Deepak, A.

1980-01-01

The results are presented of investigations on the various aspects of multiple scattering effects on visible and infrared laser beams transversing dense fog oil aerosols contained in a chamber (4' x 4' x 9'). The report briefly describes: (1) the experimental details and measurements; (2) analytical representation of the aerosol size distribution data by two analytical models (the regularized power law distribution and the inverse modified gamma distribution); (3) retrieval of aerosol size distributions from multispectral optical depth measurements by two methods (the two and three parameter fast table search methods and the nonlinear least squares method); (4) modeling of the effects of aerosol microphysical (coagulation and evaporation) and dynamical processes (gravitational settling) on the temporal behavior of aerosol size distribution, and hence on the extinction of four laser beams with wavelengths 0.44, 0.6328, 1.15, and 3.39 micrometers; and (5) the exact and approximate formulations for four methods for computing the effects of multiple scattering on the transmittance of laser beams in dense aerosols, all of which are based on the solution of the radiative transfer equation under the small angle approximation.

Lower energy and pulse stacking. A safer alternative for skin tightening using fractional CO2 laser.

PubMed

Motta, Marcos Matias; Stelini, Rafael Fantelli; Calderoni, Davi Reis; Gilioli, Rovilson; Kharmandayan, Paulo

2016-01-01

To evaluate the effect of different energies and stacking in skin shrinkage. Three decreasing settings of a fractional CO2 laser were applied to the abdomen of Twenty five Wistar rats divided into three groups. Group I (n=5) was histologically evaluated for microthermal zones dimensions. Groups II and III (n=10 each) were macroscopic evaluated with freeware ImageJ for area contraction immediately and after 30 and 60 days. No statistical significance was found within microthermal zone histological dimensions (Group I) in all settings studied. (Ablation depth: 76.90 to 97.18µm; Coagulation depth: 186.01 to 219.84 µm). In Group II, macroscopic evaluation showed that all settings cause significant immediate skin contraction. The highest setting cause significant more intense tightening effect initially, contracting skin area from 258.65 to 179.09 mm2. The same pattern was observed in Group III. At 30 and 60 days, the lowest setting significantly sustained contraction. Lower fractional CO2 laser energies associated to pulse stacking could cause consistent and long lasting tissue contraction in rats.

Investigation of multiple scattering effects in aerosols

NASA Astrophysics Data System (ADS)

Deepak, A.

1980-05-01

The results are presented of investigations on the various aspects of multiple scattering effects on visible and infrared laser beams transversing dense fog oil aerosols contained in a chamber (4' x 4' x 9'). The report briefly describes: (1) the experimental details and measurements; (2) analytical representation of the aerosol size distribution data by two analytical models (the regularized power law distribution and the inverse modified gamma distribution); (3) retrieval of aerosol size distributions from multispectral optical depth measurements by two methods (the two and three parameter fast table search methods and the nonlinear least squares method); (4) modeling of the effects of aerosol microphysical (coagulation and evaporation) and dynamical processes (gravitational settling) on the temporal behavior of aerosol size distribution, and hence on the extinction of four laser beams with wavelengths 0.44, 0.6328, 1.15, and 3.39 micrometers; and (5) the exact and approximate formulations for four methods for computing the effects of multiple scattering on the transmittance of laser beams in dense aerosols, all of which are based on the solution of the radiative transfer equation under the small angle approximation.

Improvement of Hungarian Joint Terminal Attack Program

DTIC Science & Technology

2013-06-13

LST Laser Spot Tracker NVG Night Vision Goggle ROMAD Radio Operator Maintainer and Driver ROVER Remotely Operated Video Enhanced Receiver TACP...visual target designation. The other component consists of a laser spot tracker (LST), which identifies targets by tracking laser energy reflecting...capability for every type of night time missions, laser spot tracker for laser spot search missions, remotely operated video enhanced receiver

Application of alum and chickpea (cicer arietinum) in removing color from leachate

NASA Astrophysics Data System (ADS)

Zin, N. S. M.; Awang, N. H.; Akbar, N. A.

2018-04-01

Dual coagulant has the potential to improve the coagulation process. In leachate treatment coagulation/flocculation can be used as a main treatment method or as a polishing/tertiary treatment step. Application of natural coagulant as coagulant aids able to increase the formation of floc and the removal ability of the coagulation process. This study was focusing on the ability of dual coagulants made from chemical coagulant (Alum) and natural coagulant (Cicer Arietinum (CA)) in removing colour from leachate. Jar test was carried out to investigate the effect of dose and pH on the removal ability of the dual coagulant. The optimum pH and dose for dual coagulant were obtained at pH 6.0 with dose of Alum at 4 g/L and dose of CA at 0.6 g/L with 94% removal of colour. While the optimum removal of colour for single Alum (4 g/L) and single CA (1.4 g/L) were recorded as 88% and 22%, respectively. The removals obtained using single natural and chemical coagulants were not as good as those obtained by dual coagulant. Thus, addition of CA as a coagulant aid for alum, able to increase the removal of color from leachate and has the potential to be applied as a treatment method for leachate.

Biomarkers of human cardiopulmonary response after short-term exposures to medical laser generated particulate matter from simulated procedures: a pilot study

PubMed Central

Lopez, Ramon; Farber, Mark O.; Wong, Vincent; Lacey, Steven E.

2016-01-01

Objective We conducted an exposure chamber study in humans using a simulated clinical procedure lasing porcine tissue to demonstrate evidence of effects of exposure to laser generated particulate matter (LGPM). Methods We measured pre- and post-exposure changes in exhaled nitric oxide (eNO), spirometry, heart rate variability (HRV), and blood markers of inflammation in five volunteers. Results Change in pre- and post-exposure measurements of eNO and spirometry were unremarkable. Neutrophil and lymphocyte counts increased and fibrinogen levels decreased in four of the five subjects. Measures of HRV showed decreases in the standard deviation of normal between beat intervals and sequential five-minute intervals. Conclusion These data represent the first evidence of human physiologic response to LGPM exposure. Further exploration of coagulation effects and HRV are warranted. PMID:27465102

Velocity visualization in gaseous flows

NASA Technical Reports Server (NTRS)

Hanson, R. K.

1985-01-01

Techniques are established for visualizing velocity in gaseous flows. Two approaches are considered, both of which are capable of yielding velocity simultaneously at a large number of flowfield locations, thereby providing images of velocity. The first technique employs a laser to mark specific fluid elements and a camera to track their subsequent motion. Marking is done by laser-induced phosphorescence of biacetyl, added as a tracer species in a flow of N2, or by laser-induced formation of sulfur particulates in SF6-H2-N2 mixtures. The second technique is based on the Doppler effect, and uses an intensified photodiode array camera and a planar form of laser-induced fluorescence to detect 2-d velocities of I2 (in I2-N2 mixtures) via Doppler-shifted absorption of narrow-linewidth laser radiation at 514.5 nm.

Indoor space 3D visual reconstruction using mobile cart with laser scanner and cameras

NASA Astrophysics Data System (ADS)

Gashongore, Prince Dukundane; Kawasue, Kikuhito; Yoshida, Kumiko; Aoki, Ryota

2017-02-01

Indoor space 3D visual reconstruction has many applications and, once done accurately, it enables people to conduct different indoor activities in an efficient manner. For example, an effective and efficient emergency rescue response can be accomplished in a fire disaster situation by using 3D visual information of a destroyed building. Therefore, an accurate Indoor Space 3D visual reconstruction system which can be operated in any given environment without GPS has been developed using a Human-Operated mobile cart equipped with a laser scanner, CCD camera, omnidirectional camera and a computer. By using the system, accurate indoor 3D Visual Data is reconstructed automatically. The obtained 3D data can be used for rescue operations, guiding blind or partially sighted persons and so forth.

An Investigation of Laser Lighting Systems to Assist Aircraft

DOT National Transportation Integrated Search

1979-01-01

A model for the visual detectability of narrow light beams was developed and used to evaluate the system performance of two laser lighting system configurations: (1) a laser VASI and (2) a crossed beam glide path indicator. Laboratory experiments con...

Moringa oleifera-mediated coagulation of textile wastewater and its biodegradation using novel consortium-BBA grown on agricultural waste substratum.

PubMed

Bedekar, Priyanka A; Bhalkar, Bhumika N; Patil, Swapnil M; Govindwar, Sanjay P

2016-10-01

Generation of secondary sludge is a major concern of textile dye removal by coagulation process. Combinatorial coagulation-biodegradation treatment system has been found efficient in degradation of coagulated textile dye sludge. Moringa oleifera seed powder (700 mg L -1 ) was able to coagulate textile dyestuff from real textile wastewater with 98 % color removal. Novel consortium-BBA was found to decolorize coagulated dye sludge. Parameters that significantly affect coagulation process were optimized using response surface methodology. The bench-scale stirred tank reactor (50-L capacity) designed with optimized parameters for coagulation process could efficiently remove 98, 89, 78, and 67 % of American Dye Manufacturer's Institute (ADMI) in four repetitive cycles, respectively. Solid-state fermentation composting reactor designed to treat coagulated dye sludge showed 96 % removal of dye within 10 days. Coagulation of dyes from textile wastewater and degradation of coagulated dye sludge were confirmed by Fourier transform infrared spectroscopy (FTIR) analysis. Cell morphology assay, comet assay, and phytotoxicity confirmed the formation of less toxic products after coagulation and degradation mechanism.

Histologic evaluation of laser lipolysis comparing continuous wave vs pulsed lasers in an in vivo pig model.

PubMed

Levi, Jessica R; Veerappan, Anna; Chen, Bo; Mirkov, Mirko; Sierra, Ray; Spiegel, Jeffrey H

2011-01-01

To evaluate acute and delayed laser effects of subdermal lipolysis and collagen deposition using an in vivo pig model and to compare histologic findings in fatty tissue after continuous wave diode (CW) vs pulsed laser treatment. Three CW lasers (980, 1370, and 1470 nm) and 3 pulsed lasers (1064, 1320, and 1440 nm) were used to treat 4 Göttingen minipigs. Following administration of Klein tumescent solution, a laser cannula was inserted at the top of a 10 × 2.5-cm rectangle and was passed subdermally to create separate laser "tunnels." Temperatures at the surface and at intervals of 4-mm to 20-mm depths were recorded immediately after exposure and were correlated with skin injury. Full-thickness cutaneous biopsy specimens were obtained at 1 day, 1 week, and 1 month after exposure and were stained with hematoxylin-eosin and trichrome stain. Qualitative and semiquantitative histopathologic evaluations were performed with attention to vascular damage, lipolysis, and collagen deposition. Skin surface damage occurred at temperatures exceeding 46°C. Histologic examination at 1 day after exposure showed hemorrhage, fibrous collagen fiber coagulation, and adipocyte damage. Adipocytes surrounded by histiocytes, a marker of lipolysis, were present at 1 week and 1 month after exposure. Collagen deposition in subdermal fatty tissue and in reticular dermis of some specimens was noted at 1 week and had increased at 1 month. Tissue treated with CW laser at 1470 nm demonstrated greater hemorrhage and more histiocytes at damage sites than tissue treated with pulsed laser at 1440 nm. There was a trend toward more collagen deposition with pulsed lasers than with CW lasers, but this was not statistically significant. Histopathologic comparison between results of CW laser at 980 nm vs pulsed laser at 1064 nm showed the same trend. Hemorrhage differences may result from pulse duration variations. A theoretical calculation estimating temperature rise in vessels supported this hypothesis. Pulsed lasers with higher peak powers provided better hemostatic effects than CW lasers. The degree of lipolysis depended on wavelength, laser power, and energy density. Subdermal laser irradiation can stimulate collagen deposition in subdermal tissue and reticular dermis.

Optoacoustic monitoring of cutting efficiency and thermal damage during laser ablation.

PubMed

Bay, Erwin; Douplik, Alexandre; Razansky, Daniel

2014-05-01

Successful laser surgery is characterized by a precise cut and effective hemostasis with minimal collateral thermal damage to the adjacent tissues. Consequently, the surgeon needs to control several parameters, such as power, pulse repetition rate, and velocity of movements. In this study we propose utilizing optoacoustics for providing the necessary real-time feedback of cutting efficiency and collateral thermal damage. Laser ablation was performed on a bovine meat slab using a Q-switched Nd-YAG laser (532 nm, 4 kHz, 18 W). Due to the short pulse duration of 7.6 ns, the same laser has also been used for generation of optoacoustic signals. Both the shockwaves, generated due to tissue removal, as well as the normal optoacoustic responses from the surrounding tissue were detected using a single broadband piezoelectric transducer. It has been observed that the rapid reduction in the shockwave amplitude occurs as more material is being removed, indicating decrease in cutting efficiency, whereas gradual decrease in the optoacoustic signal likely corresponds to coagulation around the ablation crater. Further heating of the surrounding tissue leads to carbonization accompanied by a significant shift in the optoacoustic spectra. Our results hold promise for real-time monitoring of cutting efficiency and collateral thermal damage during laser surgery. In practice, this could eventually facilitate development of automatic cut-off mechanisms that will guarantee an optimal tradeoff between cutting and heating while avoiding severe thermal damage to the surrounding tissues.

Palliative treatment of malignant stenoses of the lower airways with the FIBERTOM Nd:YAG laser

NASA Astrophysics Data System (ADS)

Pirozynski, Michal; Polubiec-Kownacka, Malgorzata; Strojecki, Krzysztof; Blachnio, Antoni; Pawlak, Wieslaw; Krusiewicz, Jan

1996-03-01

Neodymium yttrium aluminum garnet (Nd:YAG) laser, with its infrared wavelength of 1064 nm, is at present the most useful modality in treatment of lower airways obstruction of the lower airways by malignant and benign lesions. In fact that was the first indication for a successful restoration of a narrowed airway by Toty et al. The therapeutical effects of this laser are based on thermal action. The exposed tissue undergoes a progressive transformation by a localized increase in the temperature from warming, protein coagulation, to evaporation of water and vaporization of the tissue. This study represents the initial experience with the use of the FIBERTOMTM Nd:YAG laser in removal of obstructing malignant and non- malignant lesions of the lower airways. Twenty-six patients (mean age 55.7 plus or minus 17.4 years) were included in the study. The main indications for laser therapy were in 16 patients exophytic cancerous lesions of the trachea and main bronchi, benign tumors of the major airways in 6, and in 4 cancerous lesions of the lobar bronchi. Squamous cell lung cancer and adenocarcinoma were diagnosed most often. The degree of obstruction ranged from 70% to 99%. Complete recanalization was achieved in 19 of the 26 patients, in only one patient recanalization was not achieved. The major complication was fever -- seen in 17 (65.4%) patients and cough (19.2%). Long term observation identified 18 patients alive after 52 weeks following laser therapy.

Intravitreal Aflibercept Injection in Eyes With Substantial Vision Loss After Laser Photocoagulation for Diabetic Macular Edema: Subanalysis of the VISTA and VIVID Randomized Clinical Trials.

PubMed

Wykoff, Charles C; Marcus, Dennis M; Midena, Edoardo; Korobelnik, Jean-François; Saroj, Namrata; Gibson, Andrea; Vitti, Robert; Berliner, Alyson J; Williams Liu, Zinaria; Zeitz, Oliver; Metzig, Carola; Schmelter, Thomas; Heier, Jeffrey S

2016-12-22

Information on the effect of anti-vascular endothelial growth factor therapy in eyes with diabetic macular edema (DME) with vision loss after macular laser photocoagulation is clinically valuable. To evaluate visual and anatomic outcomes in a subgroup of macular laser photocoagulation treatment control (hereafter laser control) eyes with substantial vision loss receiving treatment with intravitreal aflibercept injection. This investigation was a post hoc analysis of a subgroup of laser control eyes in 2 phase 3 trials-VISTA (Study of Intravitreal Aflibercept Injection in Patients With Diabetic Macular Edema) and VIVID (Intravitreal Aflibercept Injection in Vision Impairment Due to DME)-in a multicenter setting. One hundred nine laser control eyes with center-involving DME were included. Treatment with intravitreal aflibercept injection (2 mg) every 8 weeks after 5 monthly doses with sham injections on nontreatment visits starting at week 24 was initiated on meeting prespecified criteria of at least a 10-letter visual acuity loss at 2 consecutive visits or at least a 15-letter visual acuity loss from the best previous measurement at 1 visit and vision not better than at baseline. Visual and anatomic outcomes in a subgroup of laser control eyes receiving treatment with intravitreal aflibercept injection. Through week 100, a total of 63 of 154 eyes (40.9%) in VISTA and 46 of 133 eyes (34.6%) in VIVID initially randomized to laser control received treatment with intravitreal aflibercept injection. The median time from week 24 to the first intravitreal aflibercept injection treatment was 34.0 (VISTA) and 83.5 (VIVID) days. In this subgroup, the mean (SD) visual gain from baseline to week 100 was 2.2 (12.5) (VISTA) and 3.8 (10.1) (VIVID) letters. At the time of intravitreal aflibercept injection initiation, these eyes had a mean (SD) loss of 11.0 (10.1) (VISTA) and 10.0 (6.5) (VIVID) letters from baseline, and they subsequently gained a mean (SD) of 17.4 (9.7) (VISTA) and 13.6 (8.6) (VIVID) letters from the initiation of treatment with intravitreal aflibercept injection through week 100. There was a minimal mean change in central subfield thickness from baseline in these eyes at the time of intravitreal aflibercept injection initiation (an increase of 3.9 μm in VISTA and a decrease of 3.0 μm in VIVID), after which further mean (SD) reductions of 285.6 (202.6) μm (VISTA) and 313.4 (181.9) μm (VIVID) occurred through week 100. Intravitreal aflibercept injection improves visual and anatomic outcomes in eyes experiencing substantial vision loss after macular laser photocoagulation treatment for DME. clinicaltrials.gov Identifiers: NCT01363440 and NCT01331681.

Prospects of the development of the laser medical machinery for ensuring of progress of medical technologies

NASA Astrophysics Data System (ADS)

Litvin, Grigory D.; Vibornov, S. I.; Jakimenko, A. P.

1990-09-01

Medicine, arid surry in prticu1r, ha'vE rather visib1e and fixed objects and tasks On the hc1e they incILId diagnosis of thE? patological process, division of the tissues, control of tissue mtabo1ism. Each component of mdica1 practice contains in different aspects these general basic Itments EvEn now Iasr technology gives physicians thee opportunity to gain some benefit, in recognizing and measuring living obJects, modulation of metabol ism coagulation and vapor-ation of tissue water

Sialolith removal in the submandibular region using surgical diode laser: report of two cases and literature review.

PubMed

Haas, Orion Luiz; Scolari, Neimar; da Silva Meirelles, Lucas; Favoretto, André Xavier; de Oliveira, Rogério Belle

2018-03-01

Sialolithiasis is defined as the presence of one or more calcified structures within the duct of a major or minor salivary gland. It occurs as a result of deposition of calcium salts around an accumulation of organic debris in the duct lumen. The main signs and symptoms are edema and bacterial infection with abscess formation. This study aimed to report two cases of submandibular sialolithiasis treated surgically with diode laser and conduct a review of the literature by means of a systematic search. In the two cases, the calculi were located in the distal part of the submandibular duct and could be palpated intraorally. Surgery was performed in an outpatient setting under local anesthesia. A linear incision was made in the floor of the mouth, in the region of the opening of Wharton's duct, to expose and remove the calculi. Laser cutting was performed using a diode laser module coupled to a 400-μm optical fiber emitting at a wavelength of 980 nm (infrared), 2.5 W output power, and in continuous pulse mode. The use of diode laser is a safe and minimally invasive option for this type of procedure. Offering advantages such as enhanced coagulation properties and high-quality incision, absence of bleeding, low risk of nerve damage, and few comorbidities.

Histologic effects of different technologies for dissection in endoscopic surgery: Nd:YAG laser, high frequency and water-jet.

PubMed

Schurr, M O; Wehrmann, M; Kunert, W; Melzer, A; Lirici, M M; Trapp, R; Kanehira, E; Buess, G

1994-01-01

Precise cutting combined with reliable coagulation of the margins of the lesion is an important requirement for dissection techniques in endoscopic surgery. These requirements are met by the two most common ancillary energy sources applied for endoscopic dissection today, electrosurgery and "thermal lasers", mostly the Nd:YAG. For the comparison of the histological effects of monopolar and bipolar high frequency with the Nd:YAG laser an experimental in vitro and in vivo study has been performed. In order to evaluate the advantages of non thermal dissection for endoscopic procedures, a water jet cutting system was included in the in vitro study. In parenchymatous tissue the water jet was found to be the least traumatic technique, followed by bipolar high frequency, laser and monopolar high frequency. The water jet was not applicable for intestinal dissection since uncontrolled bloating of the rectal wall with uncontrolled disruption of the tissue layers occurred. A general disadvantage is that secure haemostasis in the line of incision is hard to achieve. In the microscopic comparison of the shape of the incision, the Nd:YAG laser produced the smoothest lesions with well-defined margins. The monopolar technique was more often associated with irregular and sometimes fissured margins. These results were confirmed in the in vivo part of the study (Transanal Endoscopic Microsurgery).

An updated concept of coagulation with clinical implications.

PubMed

Romney, Gregory; Glick, Michael

2009-05-01

Over the past century, a series of models have been put forth to explain the coagulation mechanism. The coagulation cascade/waterfall model has gained the most widespread acceptance. This model, however, has problems when it is used in different clinical scenarios. A more recently proposed cell-based model better describes the coagulation process in vivo and provides oral health care professionals (OHCPs) with a better understanding of the clinical implications of providing dental care to patients with potentially increased bleeding tendencies. The authors conducted a literature search using the PubMed database. They searched for key words including "coagulation," "hemostasis," "bleeding," "coagulation factors," "models," "prothrombin time," "activated partial thromboplastin time," "international normalized ratio," "anticoagulation therapy" and "hemophilia" separately and in combination. The coagulation cascade/waterfall model is insufficient to explain coagulation in vivo, predict a patient's bleeding tendency, or correlate clinical outcomes with specific laboratory screening tests such as prothrombin time, activated partial thromboplastin time and international normalized ratio. However, the cell-based model of coagulation that reflects the in vivo process of coagulation provides insight into the clinical ramifications of treating dental patients with specific coagulation factor deficiencies. Understanding the in vivo coagulation process will help OHCPs better predict a patient's bleeding tendency. In addition, applying the theoretical concept of the cell-based model of coagulation to commonly used laboratory screening tests for coagulation and bleeding will result in safer and more appropriate dental care.

Optimization of neural retinal visual motor strategies in recovery of visual acuity following acute laser-induced macula injury

NASA Astrophysics Data System (ADS)

Zwick, Harry; Ness, James W.; Loveday, J.; Molchany, Jerome W.; Stuck, Bruce E.

1997-05-01

Laser induced damage to the retina may produce immediate and serious loss in visual acuity as well as subsequent recovery of visual acuity over a 1 to 6 month post exposure period. While acuity may recover, full utilization of the foveal region may not return. In one patient, a superior/temporal preferred retinal location (PRL) was apparent, while a second patient demonstrated significant foveal involvement and contrast sensitivity more reflective of foveal than parafoveal involvement. These conditions of injury wee simulated by using an artificial scotoma technique which optically stabilized a 5 degree opacity in the center of the visual field. The transmission of spatially degraded target information in the scotoma was 0 percent, 5 percent and 95 percent. Contrast sensitivity for the 0 percent and 5 percent transmission scotoma showed broad spatial frequency suppression as opposed to a bipartite contrast sensitivity function with a narrow sensitivity loss at 3 cycles/degree for the 95 percent transmission scotoma. A PRL shift to superior temporal retina with a concomitant change in accommodation was noted as target resolution became more demanding. These findings suggest that restoration of visual acuity in human laser accidents may depend upon the functionality of complex retinal and cortical adaptive mechanisms.

Fabrication of novel bundled fiber and performance assessment for clinical applications.

PubMed

Kim, Changhwan; Jeon, Myung Jin; Jung, Jin Hyang; Yang, Jung Dug; Park, Hoyong; Kang, Hyun Wook; Lee, Ho

2014-11-01

During laser vaporization of benign prostate hyperplasia (BPH), high precision of optical fiber handling is pivotal to minimize any post-operative complications. The aim of the study was to evaluate the feasible applications of a bundled fiber to treat BPH by directionally and selectively manipulating laser light onto the targeted tissue. A bundled optical fiber, consisting of four side-firing fibers, was fabricated to selectively emit laser beams in from one to four directions. Both transmission efficiency and light distribution were qualitatively and quantitatively characterized on the bundled fiber. In terms of interstitial application of the proposed fiber with 1064 nm on porcine liver tissue, the extent of thermal denaturation was estimated and compared at various laser parameterizations and for different directions of light. From the laser source to the fiber tip, the fabricated fiber device demonstrated a total light transmission of 52%. Due to internal light reflection, a secondary beam was emitted backward from the fiber tip and was responsible for 25% of the transmission loss. According to tissue testing, the extent of tissue denaturation generally increased with laser power, irradiation time, and number of light directions. The geometrical shape of thermal coagulation correlated well with the direction of light emission. Thermal damage to the glass tube occurred during excessive heat accumulation generated by continuous irradiation. The proposed fiber can be beneficial for laser vaporization of BPH by providing a selective light direction irradiation along with minimal thermal damage. Further studies will extend the applicability of the bundled fiber to treat tubular tissue structure. © 2014 Wiley Periodicals, Inc.

Aerodynamic measurement techniques. [laser based diagnostic techniques

NASA Technical Reports Server (NTRS)

Hunter, W. W., Jr.

1976-01-01

Laser characteristics of intensity, monochromatic, spatial coherence, and temporal coherence were developed to advance laser based diagnostic techniques for aerodynamic related research. Two broad categories of visualization and optical measurements were considered, and three techniques received significant attention. These are holography, laser velocimetry, and Raman scattering. Examples of the quantitative laser velocimeter and Raman scattering measurements of velocity, temperature, and density indicated the potential of these nonintrusive techniques.

The fractional laser-induced coagulation zone characterized over time by laser scanning confocal microscopy-A proof of concept study.

PubMed

Banzhaf, Christina A; Lin, Lynlee L; Dang, Nhung; Freeman, Michael; Haedersdal, Merete; Prow, Tarl W

2018-01-01

Ablative fractional laser (AFXL) is an acknowledged technique to increase uptake of topical agents in skin. Micro thermal ablation zones (MAZs) consist of ablated vertical channels surrounded by a coagulation zone (CZ). Laser scanning confocal microscopy (LSCM) images individual MAZs at 733 nm (reflectance confocal microscopy (RCM)). Further, LSCM can image sodium fluorescein (NaF) fluorescence with 488 nm excitation (fluorescence confocal microcopy (FCM)), a small hydrophilic test molecule (370 MW, log P -1.52), which may simulate uptake, bio-distribution and kinetics of small hydrophilic drugs. To explore LSCM for combined investigations of CZ thickness and uptake, bio-distribution and kinetics of NaF in AFXL-exposed skin. Excised human abdominal skin samples were exposed to AFXL (15 mJ/microbeam, 2% density) and NaF gel (1000 μg/ml, 10 μl/cm2) in six repetitions, including untreated control samples. CZ thickness and spatiotemporal fluorescence intensities (FI) were quantified up to four hours after NaF application by RCM and FCM. Test sites were scanned to a depth of 200 μm, quantifying thickness of skin compartments (stratum corneum, epidermis, upper dermis), individual CZ thicknesses and FI in CZ and surrounding skin. RCM images established skin morphology to a depth of 200 μm. The CZ thickness measurements were feasible to a depth of 50 μm, and remained unchanged over time at 50 μm (P > 0.5). FI were detected to a depth of 160 μm and remained constant in CZ up to four hours after NaF application (15 minutes: 79 AU (73-92 AU), 60 minutes: 72 AU (58-82 AU), four hours: 78 AU (71-90 AU), P > 0.1). In surrounding skin, FI increased significantly over time, but remained lower than FI in CZ (15 minutes: 21 AU (17-22 AU), 60 minutes: 21 AU (19-26 AU), four hours: 42 (31- 48 AU), P = 0.03). AFXL-processed skin generated higher FI compared to non-laser processed skin in epidermis and upper dermis at 60 minutes and four hours (P = 0.03). By LSCM, assessment of the AFXL-induced CZ thickness was feasible to a depth of 50 μm, and assessment of FI from a small hydrophilic test molecule, NaF in CZ and surrounding skin feasible to a depth of 160 μm. Lasers Surg. Med. 50:70-77, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

A laser-sheet flow visualization technique for the large wind tunnels of the National Full-Scale Aerodynamics Complex

NASA Technical Reports Server (NTRS)

Reinath, M. S.; Ross, J. C.

1990-01-01

A flow visualization technique for the large wind tunnels of the National Full Scale Aerodynamics Complex (NFAC) is described. The technique uses a laser sheet generated by the NFAC Long Range Laser Velocimeter (LRLV) to illuminate a smoke-like tracer in the flow. The LRLV optical system is modified slightly, and a scanned mirror is added to generate the sheet. These modifications are described, in addition to the results of an initial performance test conducted in the 80- by 120-Foot Wind Tunnel. During this test, flow visualization was performed in the wake region behind a truck as part of a vehicle drag reduction study. The problems encountered during the test are discussed, in addition to the recommended improvements needed to enhance the performance of the technique for future applications.

A synchronous strobed laser light sheet for helicopter model rotor flow visualization

NASA Technical Reports Server (NTRS)

Leighty, Bradley D.; Rhodes, David B.; Jones, Stephen B.; Franke, John M.

1990-01-01

A synchronous, strobed laser light sheet has been developed for use in flow visualization of a helicopter rotor model. The light sheet strobe circuit included selectable blade position, strobe duration, and multiple pulses per revolution for rotors having 2 to 9 blades. The flow was seeded with propylene glycol. Between runs, a calibration grid board was placed in the plane of the laser sheet and recorded with the video camera at the position used to record the flow field. A slip-sync mode permitted slow motion visualization of the flow field over complete rotations of the rotor. The system was used to make two-dimensional flow field cuts of a four-bladed rotor operating at advance ratio of 0.37 at wind tunnel speeds up to 79.25 meters per second (260 feet per second).

Simple and rapid methods for purification and characterization of active coagulants from the seeds of Vigna unguiculata and Parkinsonia aculeata.

PubMed

Marobhe, N J; Dalhammar, G; Gunaratna, K R

2007-06-01

The coagulating properties of aqueous crude extracts and purified proteins of Vigna unguiculata and Parkinsonia aculeata seeds, which are traditional water coagulants in rural areas of Tanzania, were studied. The coagulation activity assays were done using one millilitre (ml) of kaolin water samples. Coagulating proteins were purified in two-step ion exchange chromatography. The properties of coagulant protein were compared with Moringa oleifera. Coagulating components eluted by 0.6 M NaCl in both coagulants are cationic proteins that have the molecular mass of about 6 kDa, which is very similar to that of M. oleifera. The proteins of V. unguiculata and P. aculeata eluted by 0.3 M NaCl also harbour coagulation activity but proteins eluted with 0.6 M NaCl have higher activity. The dosage for coagulation using purified proteins of both coagulants is about 5 to 10 times lower than that of crude seed extracts. The optimum floc settling time of water treated by crude seed extracts and purified proteins ranged between two and two and half hours. Coagulating proteins of both coagulants eluted by 0.6 M NaCl are thermoresistant and retained coagulation activity of 87% to 92% after boiling for two hours at 80 degrees C and one hour at 95 degrees C. Thermotolerant proteins of V. unguiculata eluted by 0.6 M NaCl and P. aculeata have wider pH range of 5.5 to 8.5 for coagulation activity than those of M. oleifera proteins. The present investigation reveals the possibility of using purified natural coagulants for water treatment to produce safe drinking water.

Visualization of irrigant flow and cavitation induced by Er:YAG laser within a root canal model.

PubMed

Matsumoto, Himeka; Yoshimine, Yoshito; Akamine, Akifumi

2011-06-01

Laser-activated irrigation (LAI) has recently been introduced as an innovative method for root canal irrigation. However, there is limited information about the cleaning mechanism of an Er:YAG laser. In this study, we visualized the action of laser-induced bubbles and fluid flow in vitro to better understand the physical mechanisms underlying LAI. An Er:YAG laser was equipped with a novel cone-shaped tip with a lateral emission rate of approximately 80%. Laser light was emitted at a pulse energy of 30, 50, or 70 mJ (output energy: 11, 18, or 26 mJ) and a repetition rate of 1 or 20 pulses per second, without air or water spray. Fluid flow dynamics in a root canal model were observed by using glass-bead tracers under a high-speed camera. Moreover, laser-induced bubble patterns were visualized in both free water and the root canal model. Tracers revealed high-speed motion of the fluid. A full cycle of expansion and implosion of vapor and secondary cavitation bubbles were clearly observed. In free water, the vapor bubble expanded for 220 microseconds, and its shape resembled that of an apple. In the root canal model, the vapor bubble expanded in a vertical direction along the canal wall, and bubble expansion continued for ≥700 microseconds. Furthermore, cavitation bubbles were created much more frequently in the canal model than in free water. These results suggest that the cleaning mechanism of an Er:YAG laser within the root canal might depend on rapid fluid motion caused by expansion and implosion of laser-induced bubbles. Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Visual evoked potential measurement of contrast sensitivity in a case of retinal laser injury reveals visual function loss despite normal acuity

NASA Astrophysics Data System (ADS)

Glickman, Randolph D.; Harrison, Joseph M.; Zwick, Harry; Longbotham, Harold G.; Ballentine, Charles S.; Pierce, Bennie

1996-04-01

Although visual function following retinal laser injuries has traditionally been assessed by measuring visual acuity, this measure only indicates the highest spatial frequency resolvable under high-contrast viewing conditions. Another visual psychophysical parameter is contrast sensitivity (CS), which measures the minimum contrast required for detection of targets over a range of spatial frequencies, and may evaluate visual mechanisms that do not directly subserve acuity. We used the visual evoked potential (VEP) to measure CS in a population of normal subjects and in patients with ophthalmic conditions affecting retinal function, including one patient with a laser injury in the macula. In this patient, the acuity had recovered from

Laser Refractive Surgery

NASA Astrophysics Data System (ADS)

Wynne, James

Refractive surgery has its roots in corneal transplant surgery, first performed in 1905, where the damaged or diseased cornea of a living individual is replaced by donated corneal tissue taken from a recently deceased individual. Since the cornea has no blood supply, there is no danger of organ rejection. Recognizing the exceptional healing power of corneal tissue, ophthalmologists began to explore methods of reshaping the cornea to improve the visual acuity of patients suffering from myopia, hyperopia, and astigmatism. In 1964, a procedure known as keratomileusis was introduced. In 1974, radial keratotomy (RK) was introduced. In 1981, excimer laser surgery was discovered by the speaker and his IBM Research colleagues. In 1983, the excimer laser was used to create clean, precise incisions in the cornea of enucleated calf eyes, derived from slaughter, launching the era of laser refractive surgery, with more precise and safer techniques to correct myopia, hyperopia, and stigmatism. This talk will describe the widely practiced surgical procedures known as photorefractive keratectomy (PRK) and laser-assisted in situ keratomileusis (LASIK), which have improved the visual acuity of more than 35 million people. Most patients undergoing PRK or LASIK end up with uncorrected vision better than 20/20. In 2007, development commenced on a new procedure known as small incision lenticule extraction (SMILE), employing a femtosecond laser and no excimer laser. SMILE is promoted as minimally invasive and combining the advantages of PRK and LASIK. However, long term stability of visual acuity following SMILE surgery is yet to be determined.

Pseudo colour visualization of fused multispectral laser scattering images for optical diagnosis of rheumatoid arthritis

NASA Astrophysics Data System (ADS)

Zabarylo, U.; Minet, O.

2010-01-01

Investigations on the application of optical procedures for the diagnosis of rheumatism using scattered light images are only at the beginning both in terms of new image-processing methods and subsequent clinical application. For semi-automatic diagnosis using laser light, the multispectral scattered light images are registered and overlapped to pseudo-coloured images, which depict diagnostically essential contents by visually highlighting pathological changes.

Laser-induced thermal coagulation enhances skin uptake of topically applied compounds.

PubMed

Haak, C S; Hannibal, J; Paasch, U; Anderson, R R; Haedersdal, M

2017-08-01

Ablative fractional laser (AFL) generates microchannels in skin surrounded by a zone of thermally altered tissue, termed the coagulation zone (CZ). The thickness of CZ varies according to applied wavelength and laser settings. It is well-known that AFL channels facilitate uptake of topically applied compounds, but the importance of CZ is unknown. Franz Cells were used to investigate skin uptake and permeation of fluorescent labeled polyethylene glycols (PEGs) with mean molecular weights (MW) of 350, 1,000, and 5,000 Da. Microchannels with CZ thicknesses ranging from 0 to 80 μm were generated from micro-needles (0 μm, CZ-0), and AFL (10,600 nm) applied to -80°C deep frozen skin (20 μm, CZ-20) and skin equilibrated to room temperature (80 μm, CZ-80). Channels penetrated into similar mid-dermal skin depths of 600-700 μm, and number of channels per skin area was similar. At 4 hours incubation, skin uptake of PEGs into CZ and dermis was evaluated by fluorescence microscopy at specific skin depths of 150, 400, and 1,000 μm and the transcutaneous permeation was quantified by fluorescence of receptor fluids. Overall, the highest uptake of PEGs was reached through microchannels surrounded by CZ compared to channels with no CZ (CZ-20 and CZ-80>CZ-0).The thickness of CZ affected PEG distribution in skin. A thin CZ-20 favored significantly higher mean fluorescence intensities inside CZ areas compared to CZ-80 (PEG 350, 1,000, and 5,000; P < 0.001). In dermis, the uptake through CZ-20 channels was significantly higher than through CZ-80 and CZ-0 at all skin depths (PEG 350, 1,000 and 5,000, 150-1,000 μm; P < 0.001). Correspondingly, transcutaneous permeation of PEG 350 was highest in CZ-20 compared to CZ-80 and CZ-0 samples (P < 0.001). Permeation of larger molecules (PEG 1,000 and PEG 5,000) was generally low. Uptake of topical compounds is higher through microchannels surrounded by a CZ than without a CZ. Moreover, CZ thickness influences PEG distribution, with highest PEG uptake achieved from microchannels surrounded by a thin CZ. Lasers Surg. Med. 49:582-591, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

[Coagulation and adsorption on treating the Yellow River and the impact on chlorine decay during chlorination process].

PubMed

Zhan, Xiao; Gao, Bao-yu; Liu, Bin; Xu, Chun-hua; Yue, Qin-yan

2010-05-01

Two types of inorganic polymer coagulants, polyferric chloride (PFC) and polyaluminum chloride (PAC), were chosen to treat the Yellow River water. Different dosages were investigated in order to investigate the turbidity, UV24, DOC and permanganate index removal efficiency and their coagulation mechanisms based on the Zeta potentials. The natural organic matter removal by the combination of coagulation and adsorption with powder activated carbon were analyzed based on different coagulant and adsorbent dosages and dosing orders. The effects of combination of coagulation and adsorption on the residual chlorine decay were analyzed. The results showed that the two coagulants had high turbidity removal efficiency ( > 90%). The UV254, DOC, permanganate index removal efficiency were 29.2%, 26.1% and 27.9% respectively for PAC coagulation and were 32.3%, 23.3% and 32.9% respectively for PFC. Electric neutralization played an important role in the PAC coagulation process while both adsorption bridging and electric neutralization performed when PFC was used. The removal percentage of organic matter increased with the increase coagulant and adsorbent. The adsorption after coagulation process gave the better UV254 and DOC removal efficiency than the coagulation after adsorption. The UV254 and DOC removal efficiency were 95.2% and 99.9% for PAC coagulation after adsorption and were 90.1% and 99.9% for PFC coagulation first. But adding powder activated carbon can improve floc settlement performance and maintained persistent disinfection effect.

Human infrared vision is triggered by two-photon chromophore isomerization

PubMed Central

Palczewska, Grazyna; Vinberg, Frans; Stremplewski, Patrycjusz; Bircher, Martin P.; Salom, David; Komar, Katarzyna; Zhang, Jianye; Cascella, Michele; Wojtkowski, Maciej; Kefalov, Vladimir J.; Palczewski, Krzysztof

2014-01-01

Vision relies on photoactivation of visual pigments in rod and cone photoreceptor cells of the retina. The human eye structure and the absorption spectra of pigments limit our visual perception of light. Our visual perception is most responsive to stimulating light in the 400- to 720-nm (visible) range. First, we demonstrate by psychophysical experiments that humans can perceive infrared laser emission as visible light. Moreover, we show that mammalian photoreceptors can be directly activated by near infrared light with a sensitivity that paradoxically increases at wavelengths above 900 nm, and display quadratic dependence on laser power, indicating a nonlinear optical process. Biochemical experiments with rhodopsin, cone visual pigments, and a chromophore model compound 11-cis-retinyl-propylamine Schiff base demonstrate the direct isomerization of visual chromophore by a two-photon chromophore isomerization. Indeed, quantum mechanics modeling indicates the feasibility of this mechanism. Together, these findings clearly show that human visual perception of near infrared light occurs by two-photon isomerization of visual pigments. PMID:25453064

The use of Intravenous Laser Blood Irradiation (ILBI) at 630–640 nm to prevent vascular diseases and to increase life expectancy

PubMed Central

2015-01-01

Background and Aims: The mortality rate from vascular diseases is one of the highest. The use of Intravenous Laser Blood Irradiation (ILBI) within the last 30 years has demonstrated high efficacy in the treatment of vascular, cardiac and other systemic diseases. Rationale: Laser energy at 630-640 nanometers is arguably the most effective for irradiation of blood and the vascular wall. Photons at this wavelength are absorbed by oxygen, improve microcirculation, can change the viscosity of the blood and affect vascular endothelium. Conclusions: In summary, more than 25 years of experience of using laser energy at 630-640 nm has shown that this waveband directly influences the parameters of all cells in the blood, blood plasma, the coagulation process and all the structural components of the vascular wall. Additionally, ILBI directly or indirectly affects the cells of the immune system, hormones, and exchange processes in an organism, thereby not only improving the function of the vascular system, but also the other systems of an organism. It can finally lead to lower the incidence and number of vascular diseases, and indirectly to the reduction of the number of diseases in other organs and even systemically, thus helping to prolong the lifespan. PMID:25941421

Instantaneous three-dimensional visualization of concentration distributions in turbulent flows with crossed-plane laser-induced fluorescence imaging

NASA Astrophysics Data System (ADS)

Hoffmann, A.; Zimmermann, F.; Scharr, H.; Krömker, S.; Schulz, C.

2005-01-01

A laser-based technique for measuring instantaneous three-dimensional species concentration distributions in turbulent flows is presented. The laser beam from a single laser is formed into two crossed light sheets that illuminate the area of interest. The laser-induced fluorescence (LIF) signal emitted from excited species within both planes is detected with a single camera via a mirror arrangement. Image processing enables the reconstruction of the three-dimensional data set in close proximity to the cutting line of the two light sheets. Three-dimensional intensity gradients are computed and compared to the two-dimensional projections obtained from the two directly observed planes. Volume visualization by digital image processing gives unique insight into the three-dimensional structures within the turbulent processes. We apply this technique to measurements of toluene-LIF in a turbulent, non-reactive mixing process of toluene and air and to hydroxyl (OH) LIF in a turbulent methane-air flame upon excitation at 248 nm with a tunable KrF excimer laser.

New combat laser and ballistic eye protection goggles

NASA Astrophysics Data System (ADS)

Belkin, Michael

1996-04-01

Up to 10% of all combat casualties involve eye injuries which are becoming more severe, bilateral and likely to lead to a retained intraocular foreign body. The modern battlefield is permeated with laser radiation from range finders, target designators and perhaps laser weapons aimed at producing visual incapacitation. In future wars, therefore, the likelihood of eye injuries is very high. We sought to devise means to protect the eye from military relevant injurious agents. Almost all ballistic injuries can be prevented by using polycarbonate goggles. They must not, however, interfere with the soldier's functions such as the use of binoculars or limit his visual fields. These problems are not insurmountable and we shall demonstrate new goggles design which we believe will be acceptable to the troops. The solution to laser protection is more difficult. For that purpose the goggles include outserts filters for various groups of laser wavelengths. The soldier will use the appropriate filter according to a reading from a laser detector which will indicate which filter is protective against the wavelength detected.

Probe-based confocal laser endomicroscopy (pCLE) - a new imaging technique for in situ localization of spermatozoa.

PubMed

Trottmann, Matthias; Stepp, Herbert; Sroka, Ronald; Heide, Michael; Liedl, Bernhard; Reese, Sven; Becker, Armin J; Stief, Christian G; Kölle, Sabine

2015-05-01

In azoospermic patients, spermatozoa are routinely obtained by testicular sperm extraction (TESE). However, success rates of this technique are moderate, because the site of excision of testicular tissue is determined arbitrarily. Therefore the aim of this study was to establish probe-based laser endomicroscopy (pCLE) a noval biomedical imaging technique, which provides the opportunity of non-invasive, real-time visualisation of tissue at histological resolution. Using pCLE we clearly visualized longitudinal and horizontal views of the tubuli seminiferi contorti and localized vital spermatozoa. Obtained images and real-time videos were subsequently compared with confocal laser scanning microscopy (CLSM) of spermatozoa and tissues, respectively. Comparative visualization of single native Confocal laser scanning microscopy (CLSM, left) and probe-based laser endomicroscopy (pCLE, right) using Pro Flex(TM) UltraMini O after staining with acriflavine. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Overview of the coagulation system.

PubMed

Palta, Sanjeev; Saroa, Richa; Palta, Anshu

2014-09-01

Coagulation is a dynamic process and the understanding of the blood coagulation system has evolved over the recent years in anaesthetic practice. Although the traditional classification of the coagulation system into extrinsic and intrinsic pathway is still valid, the newer insights into coagulation provide more authentic description of the same. Normal coagulation pathway represents a balance between the pro coagulant pathway that is responsible for clot formation and the mechanisms that inhibit the same beyond the injury site. Imbalance of the coagulation system may occur in the perioperative period or during critical illness, which may be secondary to numerous factors leading to a tendency of either thrombosis or bleeding. A systematic search of literature on PubMed with MeSH terms 'coagulation system, haemostasis and anaesthesia revealed twenty eight related clinical trials and review articles in last 10 years. Since the balance of the coagulation system may tilt towards bleeding and thrombosis in many situations, it is mandatory for the clinicians to understand physiologic basis of haemostasis in order to diagnose and manage the abnormalities of the coagulation process and to interpret the diagnostic tests done for the same.

Overview of the coagulation system

PubMed Central

Palta, Sanjeev; Saroa, Richa; Palta, Anshu

2014-01-01

Coagulation is a dynamic process and the understanding of the blood coagulation system has evolved over the recent years in anaesthetic practice. Although the traditional classification of the coagulation system into extrinsic and intrinsic pathway is still valid, the newer insights into coagulation provide more authentic description of the same. Normal coagulation pathway represents a balance between the pro coagulant pathway that is responsible for clot formation and the mechanisms that inhibit the same beyond the injury site. Imbalance of the coagulation system may occur in the perioperative period or during critical illness, which may be secondary to numerous factors leading to a tendency of either thrombosis or bleeding. A systematic search of literature on PubMed with MeSH terms ‘coagulation system, haemostasis and anaesthesia revealed twenty eight related clinical trials and review articles in last 10 years. Since the balance of the coagulation system may tilt towards bleeding and thrombosis in many situations, it is mandatory for the clinicians to understand physiologic basis of haemostasis in order to diagnose and manage the abnormalities of the coagulation process and to interpret the diagnostic tests done for the same. PMID:25535411

Coagulation behavior and floc characteristics of a novel composite poly-ferric aluminum chloride-polydimethyl diallylammonium chloride coagulant with different OH/(Fe3+ + Al3+) molar ratios.

PubMed

Sun, Cuizhen; Qiu, Jinwei; Zhang, Zhibin; Marhaba, Taha F; Zhang, Yanhao

2016-10-01

In this paper, flocculating performance and mechanisms of a new composite coagulant, poly-ferric aluminum chloride-polydimethyl diallylammonium chloride (PFAC-PD) with different OH - /(Fe 3+ + Al 3+ ) molar ratios, were investigated for humic acid (HA)-kaolin synthetic wastewater treatment. The impact of OH - /(Fe 3+ + Al 3+ ) molar ratios on the removal efficiencies of turbidity and dissolved organic carbon, specific UV absorbance, coagulation mechanisms and dynamics was explored during the coagulation process using composite coagulants. The coagulation experimental results revealed that the composite coagulants with lower OH - /(Fe 3+ + Al 3+ ) molar ratio exhibited better coagulation efficiency. When OH - /(Fe 3+ + Al 3+ ) molar ratio of the composite coagulant was 1.5, adsorption-bridging played a dominant role in coagulating HA-kaolin synthetic wastewater. The floc growth rate and floc size, increased with increasing OH - /(Fe 3+ + Al 3+ ) molar ratio and the highest peak height of the size distribution was obtained by PFAC-PD with OH - /(Fe 3+ + Al 3+ ) = 1.5. Also, the composite coagulants with higher OH - /(Fe 3+ + Al 3+ ) molar ratio formed more compact flocs, as reflected by the higher fractal dimension value. The flocs coagulated by PFAC-PD with basicity value of 1.0 gave strong strength and good recoverability.

Effects of 532 nm pulsed-KTP laser parameters on vessel ablation in the avian chorioallantoic membrane: implications for vocal fold mucosa.

PubMed

Broadhurst, Matthew S; Akst, Lee M; Burns, James A; Kobler, James B; Heaton, James T; Anderson, R Rox; Zeitels, Steven M

2007-02-01

Selective vascular ablation (photoangiolysis) using pulsed lasers that target hemoglobin is an effective treatment strategy for many vocal fold lesions. However, vessel rupture with extravasation of blood reduces selectivity for vessels, which is frequently observed with the 0.45-ms, 585-nm pulsed dye laser. Previous studies have shown that vessel rupture is the result of vaporization of blood, an event that varies with laser pulse width and pulse fluence (energy per unit area). Clinical observations using a 532-nm wavelength pulsed potassium-titanyl-phosphate (KTP) laser revealed less laser-induced hemorrhage than the pulsed dye laser. This study investigated settings for the pulsed KTP laser to achieve selective vessel destruction without rupture using the avian chorioallantoic membrane under conditions similar to flexible laryngoscopic delivery of the laser in clinical practice. The chick chorioallantoic membrane offers convenient access to many small blood vessels similar in size to those targeted in human vocal fold. Using a 532-nm pulsed KTP laser, pulse width, pulse energy, and working distance from the optical delivery fiber were varied to assess influence on the ability to achieve vessel coagulation without vessel wall rupture. Third-order vessels (n = 135) were irradiated: Energy (471-550 mJ), pulse width (10, 15, 30 ms), and fiber-to-tissue distance (1 mm, 3 mm) were varied systematically. Selective vessel destruction without vessel wall rupture was more often achieved by increasing pulse width, increasing the fiber-to-tissue distance, and decreasing energy. Vessel destruction without rupture was consistently achieved using 15- or 30-ms pulses with a fiber-to-tissue distance of 3 mm (pulse fluence of 13-16 J/cm). This study substantiates our clinical observation that a 532-nm pulsed KTP laser was effective for ablating microcirculation while minimizing vessel wall rupture and hemorrhage.

Femtosecond Laser Flap Creation for Laser In Situ Keratomileusis in the Setting of Previous Radial Keratotomy.

PubMed

Rush, Sloan W; Rush, Ryan B

2015-01-01

The aim of the study was to report the outcomes of laser in situ keratomileusis (LASIK) in subjects with previous radial keratotomy (RK) using a novel femtosecond laser setting on a proprietary femtosecond laser platform. This was a retrospective, consecutive chart review of patients at a single private practice institution. The medical records of 16 eyes of 8 subjects who underwent femtosecond-assisted LASIK for consecutive hyperopia after RK were retrospectively reviewed. The preoperative characteristics, intraoperative details, and postoperative outcomes were analyzed. All 16 eyes had successful femtosecond laser flap creation without significant intraoperative or postoperative complications. Uncorrected visual acuity significantly improved postoperatively (P = 0.0142) and remained stable through the final follow-up interval at 9 to 12 months postoperatively. None of the subjects lost any lines of best spectacle-corrected visual acuity in the postoperative period. The novel femtosecond laser technique described in this study can provide a safe and effective method for patients undergoing LASIK after previous RK. Future investigations are required to further validate the findings reported in this study.

Administration of tissue plasminogen activator without coagulation results in a Chinese population.

PubMed

Qin, Xiaoming; Zhao, Songyao; Yin, Liujie; Dou, Hailing; Chen, Jie; Wang, Yifan; Li, Mingzhe; Chen, Ruifang; Fu, Jing; Liu, Wei; Liu, Xin; Yang, Gaiqing; Wang, Runqing; Jia, Xinzhou; Bu, Shufang; Ma, Dongpu; Wang, Baoyu; Li, Shize

2018-03-01

Routine coagulation test before intravenous tissue plasminogen activator (tPA) use increases the door to needle time (DNT). We sought to evaluate the safety of tPA use without coagulation results and its impact on prognosis. In our stroke registry, tPA was delivered with coagulation results from December 2015 to April 2016 and without coagulation results from May 2016 to December 2016. Differences of demographics, clinical characteristic, and prognosis between these two groups were analyzed. In addition, logistic regression analysis was conducted to identify predictors for DNT of over 60 min. A total of 201 stroke patients were included in the final analysis. Of these, 81 patients received tPA with coagulation results and 120 patients without coagulation results. Only one (0.8%) patient with abnormal coagulation results met the exclusion criteria of tPA use in patients without coagulation results. The difference of DNT between groups with (mean, 61.7 min) and without (mean, 41.9 min) coagulation results was significant (P = 0.00). The group without coagulation results had a higher rate of favorable 90-day outcome (74.2 vs 70.4%) and lower rates of symptomatic intracranial hemorrhage/nonintracranial hemorrhage (4.9 and 22.2% vs 1.7 and 19.2%) than the group with coagulation results did; these differences were not statistically significant. In multivariate analysis, only tPA use with coagulation results was the predictor for DNT of over 60 min (P = 0.0030, OR = 2.44, 95% CI 1.28-4.65). The present study suggests that tPA could be delivered safely without coagulation results in patients without suspected coagulopathy, and avoiding coagulation tests reduces significantly the DNT interval.

Comparison of single-step and two-step purified coagulants from Moringa oleifera seed for turbidity and DOC removal.

PubMed

Sánchez-Martín, J; Ghebremichael, K; Beltrán-Heredia, J

2010-08-01

The coagulant proteins from Moringa oleifera purified with single-step and two-step ion-exchange processes were used for the coagulation of surface water from Meuse river in The Netherlands. The performances of the two purified coagulants and the crude extract were assessed in terms of turbidity and DOC removal. The results indicated that the optimum dosage of the single-step purified coagulant was more than two times higher compared to the two-step purified coagulant in terms of turbidity removal. And the residual DOC in the two-step purified coagulant was lower than in single-step purified coagulant or crude extract. (c) 2010 Elsevier Ltd. All rights reserved.

Recurrence of cervical intraepithelial lesions after thermo-coagulation in HIV-positive and HIV-negative Nigerian women.

PubMed

Oga, Emmanuel A; Brown, Jessica P; Brown, Clayton; Dareng, Eileen; Adekanmbi, Victor; Odutola, Michael; Olaniyan, Olayinka; Offiong, Richard; Obende, Kayode; Adewole, Ayodele Stephen; Peter, Achara; Dakum, Patrick; Adebamowo, Clement

2016-05-11

The burden of cervical cancer remains huge globally, more so in sub-Saharan Africa. Effectiveness of screening, rates of recurrence following treatment and factors driving these in Africans have not been sufficiently studied. The purpose of this study therefore was to investigate factors associated with recurrence of cervical intraepithelial lesions following thermo-coagulation in HIV-positive and HIV-negative Nigerian women using Visual Inspection with Acetic Acid (VIA) or Lugol's Iodine (VILI) for diagnosis. A retrospective cohort study was conducted, recruiting participants from the cervical cancer "see and treat" program of IHVN. Data from 6 sites collected over a 4-year period was used. Inclusion criteria were: age ≥18 years, baseline HIV status known, VIA or VILI positive and thermo-coagulation done. Logistic regression was performed to examine the proportion of women with recurrence and to examine factors associated with recurrence. Out of 177 women included in study, 67.8 % (120/177) were HIV-positive and 32.2 % (57/177) were HIV-negative. Recurrence occurred in 16.4 % (29/177) of participants; this was 18.3 % (22/120) in HIV-positive women compared to 12.3 % (7/57) in HIV-negative women but this difference was not statistically significant (p-value 0.31). Women aged ≥30 years were much less likely to develop recurrence, adjusted OR = 0.34 (95 % CI = 0.13, 0.92). Among HIV-positive women, CD4 count <200cells/mm(3) was associated with recurrence, adjusted OR = 5.47 (95 % CI = 1.24, 24.18). Recurrence of VIA or VILI positive lesions after thermo-coagulation occurs in a significant proportion of women. HIV-positive women with low CD4 counts are at increased risk of recurrent lesions and may be related to immunosuppression.

Intraoperative Changes in Blood Coagulation and Thrombelastographic Monitoring in Liver Transplantation

PubMed Central

Kang, Yoo Goo; Martin, Douglas J.; Marquez, Jose; Lewis, Jessica H.; Bontempo, Franklin A.; Shaw, Byers W.; Starzl, Thomas E.; Winter, Peter M.

2010-01-01

The blood coagulation system of 66 consecutive patients undergoing consecutive liver transplantations was monitored by thrombelastograph and analytic coagulation profile. A poor preoperative coagulation state, decrease in levels of coagulation factors, progressive fibrinolysis, and whole blood clot lysis were observed during the preanhepatic and anhepatic stages of surgery. A further general decrease in coagulation factors and platelets, activation of fibrinolysis, and abrupt decrease in levels of factors V and VIII occurred before and with reperfusion of the homograft. Recovery of blood coagulability began 30–60 min after reperfusion of the graft liver, and coagulability had returned toward baseline values 2 hr after reperfusion. A positive correlation was shown between the variables of thrombelastography and those of the coagulation profile. Thrombelastography was shown to be a reliable and rapid monitoring system. Its use was associated with a 33% reduction of blood and fluid infusion volume, whereas blood coagulability was maintained without an increase in the number of blood product donors. PMID:3896028

Modifying the visual appearance of metal nanoparticle composites by infrared laser annealing

NASA Astrophysics Data System (ADS)

Halabica, Andrej; Indrobo, J. C.; Magruder, R. H., III; Haglund, R. F., Jr.; Epp, J. M.; Rashkeev, S.; Boatner, L. A.; Pennycook, S. J.; Pantelides, S. T.

2007-03-01

It has long been known that noble-metal nanoparticles in insulators can alter their visual appearance. Many metal nanoparticle composites can be created by ion implantation and subsequent annealing to initiate phase separation, nucleation and growth of nanoparticles. The size and size distribution of the nanoparticles - and therefore the color of the composite - are determined by the chemistry and thermodynamics of the annealing process. In this paper we report that we can also alter the color of gold- and silver-implanted silica and alumina by tunable infrared laser irradiation. Essentially a variant of rapid thermal annealing, this laser treatment can shift the plasmon band of the nanoparticles by tens of nm, resulting in significantly altered visual appearance. The amount of energy delivered to the implanted layer, and the subsequent color variation, can be adjusted by changing the wavelength and fluence of the laser. This makes it possible, as we will show, to write or pattern the composite material with 200 μm linewidths. This work is partially supported by DOE (DE-AC05-00OR22725), NSF (DMR-0513048), and by Alcoa Inc.

Imaging of endodontic biofilms by combined microscopy (FISH/cLSM - SEM).

PubMed

Schaudinn, C; Carr, G; Gorur, A; Jaramillo, D; Costerton, J W; Webster, P

2009-08-01

Scanning electron microscopy is a useful imaging approach for the visualization of bacterial biofilms in their natural environments including their medical and dental habitats, because it allows for the exploration of large surfaces with excellent resolution of topographic features. Most biofilms in nature, however, are embedded in a thick layer of extracellular matrix that prevents a clear identification of individual bacteria by scanning electron microscopy. The use of confocal laser scanning microscopy on the other hand in combination with fluorescence in situ hybridization enables the visualization of matrix embedded bacteria in multi-layered biofilms. In our study, fluorescence in situ hybridization/confocal laser scanning microscopy and scanning electron microscopy were applied to visualize bacterial biofilm in endodontic root canals. The resulting fluorescence in situ hybridization /confocal laser scanning microscopy and scanning electron microscopy and pictures were subsequently combined into one single image to provide high-resolution information on the location of hidden bacteria. The combined use of scanning electron microscopy and fluorescence in situ hybridization / confocal laser scanning microscopy has the potential to overcome the limits of each single technique.

Enhanced Monocular Visual Odometry Integrated with Laser Distance Meter for Astronaut Navigation

PubMed Central

Wu, Kai; Di, Kaichang; Sun, Xun; Wan, Wenhui; Liu, Zhaoqin

2014-01-01

Visual odometry provides astronauts with accurate knowledge of their position and orientation. Wearable astronaut navigation systems should be simple and compact. Therefore, monocular vision methods are preferred over stereo vision systems, commonly used in mobile robots. However, the projective nature of monocular visual odometry causes a scale ambiguity problem. In this paper, we focus on the integration of a monocular camera with a laser distance meter to solve this problem. The most remarkable advantage of the system is its ability to recover a global trajectory for monocular image sequences by incorporating direct distance measurements. First, we propose a robust and easy-to-use extrinsic calibration method between camera and laser distance meter. Second, we present a navigation scheme that fuses distance measurements with monocular sequences to correct the scale drift. In particular, we explain in detail how to match the projection of the invisible laser pointer on other frames. Our proposed integration architecture is examined using a live dataset collected in a simulated lunar surface environment. The experimental results demonstrate the feasibility and effectiveness of the proposed method. PMID:24618780

Femtosecond laser-assisted cataract surgeries reported to the European Registry of Quality Outcomes for Cataract and Refractive Surgery: Baseline characteristics, surgical procedure, and outcomes.

PubMed

Lundström, Mats; Dickman, Mor; Henry, Ype; Manning, Sonia; Rosen, Paul; Tassignon, Marie-José; Young, David; Stenevi, Ulf

2017-12-01

To describe a large cohort of femtosecond laser-assisted cataract surgeries in terms of baseline characteristics and the related outcomes. Eighteen cataract surgery clinics in 9 European countries and Australia. Prospective multicenter case series. Data on consecutive eyes having femtosecond laser-assisted cataract surgery in the participating clinics were entered in the European Registry of Quality Outcomes for Cataract and Refractive Surgery (EUREQUO). A trained registry manager in each clinic was responsible for valid reporting to the EUREQUO. Demographics, preoperative corrected distance visual acuity (CDVA), risk factors, type of surgery, type of intraocular lens, visual outcomes, refractive outcomes, and complications were reported. Complete data were available for 3379 cases. The mean age was 64.4 years ± 10.9 (SD) and 57.8% (95% confidence interval [CI], 56.1-59.5) of the patients were women. A surgical complication was reported in 2.9% of all cases (95% CI, 2.4-3.5). The mean postoperative CDVA was 0.04 ± 0.15. logarithm of the minimum angle of resolution. A biometry prediction error (spherical equivalent) was within ±0.5 diopter in 71.8% (95% CI, 70.3-73.3) of all surgeries. Postoperative complications were reported in 3.3% (95% CI, 2.7-4.0). Patients with good preoperative CDVA had the best visual and refractive outcomes; patients with poor preoperative visual acuity had poorer outcomes. The visual and refractive outcomes of femtosecond laser-assisted cataract surgery were favorable compared with manual phacoemulsification. The outcomes were highly influenced by the preoperative visual acuity, but all preoperative CDVA groups had acceptable outcomes. Copyright © 2017 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Blood coagulation status of small-for-dates and postmature infants.

PubMed Central

Perlman, M; Dvilansky, A

1975-01-01

In a prospective study of blood coagulation status in small-for-dates and postmature infants there was often evidence of intravascular coagulation. Abnormal coagulation findings correlated with the degree of growth retardation and with the degree of postmaturity. Macroscopical placental infarction and neonatal polycythaemia were associated with coagulation abnormalities; asphyxia, however, was not. Intravascular coagulation may be an additional hazard to small-for-dates and postmature infants. PMID:1170815

Preparation and Evaluation of Titanium-Based Xerogel as a Promising Coagulant for Water/Wastewater Treatment.

PubMed

Wang, Xiaomeng; Li, Minghui; Song, Xiaojie; Chen, Zhihao; Wu, Bingdang; Zhang, Shujuan

2016-09-06

The nontoxicity of titanium (Ti) and the potential to produce valuable photocatalysts from the final coagulated sludge constitute the main advantages of Ti-based coagulants over conventional ones. However, the low effluent pH and the too-fast hydrolysis limit the wide application of Ti-salt coagulants. Prehydrolysis, to some extent, is helpful to improve the coagulation performance of Ti-salt coagulants. However, the prehydrolyzed polytitanium chloride (PTC) still suffers from narrow applicable dose/pH range. A novel and efficient Ti-based coagulant, denoted as titanium xerogel coagulant (TXC), was successfully prepared by the sol-gel method with TiCl4 as the precursor and acetylacetone as a modifying agent. Compared with TiCl4, a PTC, and a commercial polyferric sulfate, the resulting TXC possessed a larger floc size, better settling property, and wider applicable coagulant dose/pH range. Moreover, the effluent pH after TXC coagulation was not significantly reduced, avoiding the corrosion problem sometimes caused by the low effluent pH. TXC exhibited good coagulation performance for several real wastewaters, especially for the wastewaters of low turbidity. These results demonstrate that gelation was a more effective strategy than prehydrolysis to overcome the inherent weaknesses of Ti salts as a type of promising coagulants.

Visualization of the 3-dimensional flow around a model with the aid of a laser knife

NASA Technical Reports Server (NTRS)

Borovoy, V. Y.; Ivanov, V. V.; Orlov, A. A.; Kharchenko, V. N.

1984-01-01

A method for visualizing the three-dimensional flow around models of various shapes in a wind tunnel at a Mach number of 5 is described. A laser provides a planar light flux such that any plane through the model can be selectively illuminated. The shape of shock waves and separation regions is then determined by the intensity of light scattered by soot particles in the flow.

Laser optical method of visualizing cutaneous blood vessels and its applications in biometry and photomedicine

NASA Astrophysics Data System (ADS)

Asimov, M. M.; Asimov, R. M.; Rubinov, A. N.

2011-05-01

We propose and examine a new approach to visualizing a local network of cutaneous blood vessels using laser optical methods for applications in biometry and photomedicine. Various optical schemes of the formation of biometrical information on the architecture of blood vessels of skin tissue are analyzed. We developed an optical model of the interaction of the laser radiation with the biological tissue and a mathematical algorithm of processing of measurement results. We show that, in medicine, the visualization of blood vessels makes it possible to calculate and determine regions of disturbance of blood microcirculation and to control tissue hypoxia, as well as to maintain the local concentration of oxygen at a level necessary for the normal cellular metabolism. We propose noninvasive optical methods for modern photomedicine and biometry for diagnostics and elimination of tissue hypoxia and for personality identification and verification via the pattern of cutaneous blood vessels.

Visually augmented targeted combination light therapy for acne vulgaris: a case report.

PubMed

Yazdi, Alireza; Lyons, Colin-William; Roberts, Niamh

2017-10-31

Acne vulgaris is a common skin disease. Pharmacological modalities for treatment are proven to be efficacious but have limitations. Light therapy for acne vulgaris has shown promise in previous studies. This case report and its accompanying images show how a novel approach of visually augmented high fluence light therapy has been used to good effect. A 26-year-old Caucasian woman with acne vulgaris resistant to treatment with topical therapy underwent three sessions of combination potassium titanyl phosphate laser (532 nm)/neodymium-doped: yttrium aluminum garnet laser (1064 nm) light therapy with visually augmented narrow spot size and high fluence. A 73% reduction in total inflammatory lesions was evident 6 months after the initial treatment. This case report illustrates that there may be utility in this novel approach of narrow spot size, magnification-assisted, high fluence targeted combination laser therapy for inflammatory acne.

Rapid heating of matter using high power lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bang, Woosuk

2016-04-08

This slide presentation describes motivation (uniform and rapid heating of a target, opportunity to study warm dense matter, study of nuclear fusion reactions), rapid heating of matter with intense laser-driven ion beams, visualization of the expanding warm dense gold and diamond, and nuclear fusion experiments using high power lasers (direct heating of deuterium spheres (radius ~ 10nm) with an intense laser pulse.

Aspects of CO2 laser engraving of printing cylinders.

PubMed

Atanasov, P A; Maeno, K; Manolov, V P

1999-03-20

Results of the experimental and theoretical investigations of CO(2) laser-engraved cylinders are presented. The processed surfaces of test samples are examined by a phase-stepping laser interferometer, digital microscope, and computer-controlled profilometer. Fourier analysis is made on the patterns parallel to the axis of the laser-scribed test ceramic cylinders. The problem of the visually observed banding is discussed.

Real-Time Electrical Impedimetric Monitoring of Blood Coagulation Process under Temperature and Hematocrit Variations Conducted in a Microfluidic Chip

PubMed Central

Lei, Kin Fong; Chen, Kuan-Hao; Tsui, Po-Hsiang; Tsang, Ngan-Ming

2013-01-01

Blood coagulation is an extremely complicated and dynamic physiological process. Monitoring of blood coagulation is essential to predict the risk of hemorrhage and thrombosis during cardiac surgical procedures. In this study, a high throughput microfluidic chip has been developed for the investigation of the blood coagulation process under temperature and hematocrit variations. Electrical impedance of the whole blood was continuously recorded by on-chip electrodes in contact with the blood sample during coagulation. Analysis of the impedance change of the blood was conducted to investigate the characteristics of blood coagulation process and the starting time of blood coagulation was defined. The study of blood coagulation time under temperature and hematocrit variations was shown a good agreement with results in the previous clinical reports. The electrical impedance measurement for the definition of blood coagulation process provides a fast and easy measurement technique. The microfluidic chip was shown to be a sensitive and promising device for monitoring blood coagulation process even in a variety of conditions. It is found valuable for the development of point-of-care coagulation testing devices that utilizes whole blood sample in microliter quantity. PMID:24116099

Applying the cell-based coagulation model in the management of critical bleeding.

PubMed

Ho, K M; Pavey, W

2017-03-01

The cell-based coagulation model was proposed 15 years ago, yet has not been applied commonly in the management of critical bleeding. Nevertheless, this alternative model may better explain the physiological basis of current coagulation management during critical bleeding. In this article we describe the limitations of the traditional coagulation protein cascade and standard coagulation tests, and explain the potential advantages of applying the cell-based model in current coagulation management strategies. The cell-based coagulation model builds on the traditional coagulation model and explains many recent clinical observations and research findings related to critical bleeding unexplained by the traditional model, including the encouraging results of using empirical 1:1:1 fresh frozen plasma:platelets:red blood cells transfusion strategy, and the use of viscoelastic and platelet function tests in patients with critical bleeding. From a practical perspective, applying the cell-based coagulation model also explains why new direct oral anticoagulants are effective systemic anticoagulants even without affecting activated partial thromboplastin time or the International Normalized Ratio in a dose-related fashion. The cell-based coagulation model represents the most cohesive scientific framework on which we can understand and manage coagulation during critical bleeding.

Comparison of Moringa stenopetala seed extract as a clean coagulant with Alum and Moringa stenopetala-Alum hybrid coagulant to remove direct dye from Textile Wastewater.

PubMed

Dalvand, Arash; Gholibegloo, Elham; Ganjali, Mohammad Reza; Golchinpoor, Najmeh; Khazaei, Mohammad; Kamani, Hossein; Hosseini, Sara Sadat; Mahvi, Amir Hossein

2016-08-01

In this study, the efficiency of Moringa stenopetala seed extract was compared with alum and M. stenopetala-alum hybrid coagulant to remove Direct Red 23 azo dye from textile wastewater. The effects of parameters such as pH, coagulant dose, type of salt used for the extraction of coagulant and initial dye concentration on dye removal efficiency were investigated. Moreover, the existing functional groups on the structure of M. stenopetala coagulant (MSC) were determined by Fourier transform infrared spectroscopy, and the morphology of sludge produced by MSC, alum, and hybrid coagulant was characterized by scanning electron microscopy. Ninhydrin test was also used to determine the quantity of primary amines in the MSC and Moringa oleifera coagulant (MOC). According to the results, with increasing the coagulant dose and decreasing the initial dye concentration, dye removal efficiency has increased. The maximum dye removal of 98.5, 98.2, and 98.3 % were obtained by using 240, 120, and 80 mg/L MSC, alum and hybrid coagulant at pH 7, respectively. The results also showed MSC was much more effective than MOC for dye removal. The volume of sludge produced by MSC was one fourth and half of those produced by alum and hybrid coagulant, respectively. Based on the results, hybrid coagulant was the most efficient coagulant for direct dye removal from colored wastewater.

Accelerated defect visualization of microelectronic systems using binary search with fixed pitch-catch distance laser ultrasonic scanning

NASA Astrophysics Data System (ADS)

Park, Byeongjin; Sohn, Hoon

2018-04-01

The practicality of laser ultrasonic scanning is limited because scanning at a high spatial resolution demands a prohibitively long scanning time. Inspired by binary search, an accelerated defect visualization technique is developed to visualize defect with a reduced scanning time. The pitch-catch distance between the excitation point and the sensing point is also fixed during scanning to maintain a high signal-to-noise ratio of measured ultrasonic responses. The approximate defect boundary is identified by examining the interactions between ultrasonic waves and defect observed at the scanning points that are sparsely selected by a binary search algorithm. Here, a time-domain laser ultrasonic response is transformed into a spatial ultrasonic domain response using a basis pursuit approach so that the interactions between ultrasonic waves and defect can be better identified in the spatial ultrasonic domain. Then, the area inside the identified defect boundary is visualized as defect. The performance of the proposed defect visualization technique is validated through an experiment on a semiconductor chip. The proposed defect visualization technique accelerates the defect visualization process in three aspects: (1) The number of measurements that is necessary for defect visualization is dramatically reduced by a binary search algorithm; (2) The number of averaging that is necessary to achieve a high signal-to-noise ratio is reduced by maintaining the wave propagation distance short; and (3) With the proposed technique, defect can be identified with a lower spatial resolution than the spatial resolution required by full-field wave propagation imaging.

Effects of filtration temperature, humic acid level and alum dose on cryptosporidium sized particle breakthrough.

PubMed

Xu, G R; Fitzpatrick, C S B; Deng, L Y

2006-01-01

Recent Cryptosporidium outbreaks have highlighted concerns about filter efficiency and especially particle breakthrough. Understanding the causes of breakthrough is essential, as the parasite cannot be destroyed by conventional disinfection with chlorine. Particle breakthrough depends on many factors. This research aims to investigate the influence of temperature, humic acid (HA) level and chemical dosing on particle breakthrough in filtration. A series of temperatures were set at 5 degrees C, 15 degrees C and 25 degrees C; humic acid level was 5 mg L(-1). Each was combined with a series of Al doses. A laser particle counter was used to assess the particle breakthrough online. Turbidity, zeta potential, and UV254 absorption were measured before and after filtration. The results showed that particle breakthrough was influenced significantly by temperature, humic acid and dosing. Particle breakthrough occurred earlier at lower temperature, while at higher temperature it was reduced at the same coagulant dose. With coagulants, even at low dose, particle breakthrough was significantly reduced. With HA 5 mg L(-1), particle breakthrough was earlier and the amount was much larger than without HA even at high temperature. There was an optimal dose in filtration and it was well correlated with zeta potential.

A Modern and Interactive Approach to Learning Laser and Optical Communications.

ERIC Educational Resources Information Center

Minasian, Robert; Alameh, Kamal

2002-01-01

Discusses challenges in teaching lasers and optical communications to engineers, including the prohibitive cost of laboratory experiments, and describes the development of a computer-based photonics simulation experiment module which provides students with an understanding and visualization of how lasers can be modulated in telecommunications.…

One can achieve anything with a laser: an educational initiative

NASA Astrophysics Data System (ADS)

Davies, Ray K.

2005-06-01

Laser Photonics has been highlighted by many as THE Technology of the 21st Century. However, there are few obvious opportunities for students to see a Laser in operation in circumstances beyond some simple low power Laser Interferometry demonstrations, or the use of Laser Pointer Pens. As part of an educational initiative, PION LASER SENSORS within the University of Salford has developed a series of laboratory design and construction Projects that involve both the opportunities for, and the innovative creation of, visually attractive operative applications of low power Laser Photonics. These highly functional Laser Photonics Projects range from the transmission of audio signals to a written alphabetical letter recognition and Braille converter sensor for a visually impaired person; from a Laser speckle eye-sight testing system to a prototype mobile robotic guide for a blind person.; from a novel type of Laser seismograph to an equally novel set of Laser measurement callipers; from a Laser activated pair of walking feet to an optical feedback system to maintain a horizontal surface within a vehicle traversing rough terrain. This type of low power Laser Photonics design and construction Project not only provides the opportunity for students to become involved with some highly creative and innovative laboratory opportunities, but the experience clearly enthuses the students towards many aspects of Physics, Medicine, and Engineering through a sense of personal achievement resulting from a realization of their imaginative thinking sills, combined with their acquired manual skills.

Laser-assisted in situ keratomileusis with optimized, fast-repetition, and cyclotorsion control excimer laser to treat hyperopic astigmatism with high cylinder.

PubMed

Alió Del Barrio, Jorge L; Tiveron, Mauro; Plaza-Puche, Ana B; Amesty, María A; Casanova, Laura; García, María J; Alió, Jorge L

2017-10-18

To evaluate the visual outcomes after femtosecond laser-assisted laser in situ keratomileusis (LASIK) surgery to correct primary compound hyperopic astigmatism with high cylinder using a fast repetition rate excimer laser platform with optimized aspheric profiles and cyclotorsion control. Eyes with primary simple or compound hyperopic astigmatism and a cylinder power ≥3.00 D had uneventful femtosecond laser-assisted LASIK with a fast repetition rate excimer laser ablation, aspheric profiles, and cyclotorsion control. Visual, refractive, and aberrometric results were evaluated at the 3- and 6-month follow-up. The astigmatic outcome was evaluated using the Alpins method and ASSORT software. This study enrolled 80 eyes at 3 months and 50 eyes at 6 months. The significant reduction in refractive sphere and cylinder 3 and 6 months postoperatively (p<0.01) was associated with an improved uncorrected distance visual acuity (p<0.01). A total of 23.75% required retreatment 3 months after surgery. Efficacy and safety indices at 6 months were 0.90 and 1.00, respectively. At 6 months, 80% of eyes had an SE within ±0.50 D and 96% within ±1.00 D. No significant differences were detected between the third and the sixth postoperative months in refractive parameters. A significant increase in the spherical aberration was detected, but not in coma. The correction index was 0.94 at 3 months. Laser in situ keratomileusis for primary compound hyperopic astigmatism with high cylinder (>3.00 D) using the latest excimer platforms with cyclotorsion control, fast repetition rate, and optimized aspheric profiles is safe, moderately effective, and predictable.

Laser-assisted subepithelial keratectomy versus epipolis laser in situ keratomileusis for myopia: a meta-analysis of clinical outcomes.

PubMed

Wen, Daizong; Huang, Jinhai; Li, Xuexi; Savini, Giacomo; Feng, Yifan; Lin, Qiaoya; Wang, Qinmei

2014-01-01

To identify possible differences between laser-assisted subepithelial keratectomy and epipolis laser in situ keratomileusis for myopia. Meta-analysis. Patients from previously reported comparative studies treated by laser-assisted subepithelial keratectomy versus epipolis laser in situ keratomileusis. A systematic literature retrieval was conducted in the MEDLINE, EMBASE and Cochrane Library, up to January 2013. The included studies were subject to a meta-analysis using a RevMan 5.1 version software. The differences in efficacy, predictability, safety, epithelial healing time, pain perception and corneal haze formation. A total of six studies involving 517 eyes were included. There were no statistically significant differences in the final proportion of eyes with uncorrected visual acuity of 6/6 or better (P = 0.43), mean postoperative uncorrected visual acuity (P = 0.53), final proportion of eyes with refraction within ± 0.50 D (P = 0.62) and ± 1.00 D (P = 0.16) of target, final proportion of eyes losing two or more lines of best spectacle-corrected visual acuity (P = 1.00), healing time of corneal epithelium (P = 0.58), final proportion of eyes with corneal haze grade 0.5 or higher (P = 0.26), and corneal haze levels (P = 0.36). There were no significant differences in efficacy, predictability, safety, epithelial healing time and corneal haze formation between laser-assisted subepithelial keratectomy and epipolis laser in situ keratomileusis, but the result was limited. Future more data are required to detect the potential differences between the two procedures. © 2013 Royal Australian and New Zealand College of Ophthalmologists.

A retrospective comparison of efficacy and safety of 680 consecutive lasik treatments for high myopia performed with two generations of flying-spot excimer lasers.

PubMed

Gazieva, Lola; Beer, Mette Hjuler; Nielsen, Kim; Hjortdal, Jesper

2011-12-01

To compare the visual refractive outcome and complication of laser in situ keratomileusis (LASIK) carried out with a Carl Zeiss-Meditec MEL-70 Excimer laser and a MEL-80 laser for treatment of high myopia. Journal records of 680 consecutive eyes that underwent LASIK with a Schwind Supratome microkeratome and a MEL-70 Excimer laser (Group A), or a Moria M2 microkeratome and a MEL-80 Excimer laser (Group B) were reviewed. Manifest refraction, uncorrected and best spectacle-corrected visual acuity (BSCVA), corneal topography and central corneal thickness (CCT) were recorded before and 3 months after treatment. Pre- and postoperative complications, visual and refractive outcome and frequency of retreatments were registered. Mean preoperative spherical equivalent refraction was -8.52 dioptres (-5.50- -18 dioptres), and the mean attempted laser correction was -8.02 dioptres (-5.50- -11 dioptres). Three months after LASIK, the average treatment error (difference between achieved and attempted correction) was 1.20 (SD=1.19) dioptres of under correction in Group A and 0.52 (SD=1.00) dioptres in Group B. Four eyes lost more than two lines of BSCVA (0.6%). In 110 eyes (16%), a re-LASIK procedure was performed to reduce remaining myopia after the primary procedure. Laser in situ keratomileusis treatment for high myopia can effectively reduce high degrees of myopia. Under correction was observed in both treatment groups but Group B has a slightly better predictability. Significant loss of BSCVA occurs infrequently after LASIK for even considerable grades of myopia (0.6% in each group). © 2010 The Authors. Journal compilation © 2010 Acta Ophthalmol.

Cost-effectiveness of ranibizumab in the treatment of visual impairment due to diabetic macular edema.

PubMed

Haig, Jennifer; Barbeau, Martin; Ferreira, Alberto

2016-07-01

Objective Ranibizumab, an anti-vascular endothelial growth factor designed for ocular use, has been deemed cost-effective in multiple indications by several Health Technology Assessment bodies. This study assessed the cost-effectiveness of ranibizumab monotherapy or combination therapy (ranibizumab plus laser photocoagulation) compared with laser monotherapy for the treatment of visual impairment due to diabetic macular edema (DME). Methods A Markov model was developed in which patients moved between health states defined by best-corrected visual acuity (BCVA) intervals and an absorbing 'death' state. The population of interest was patients with DME due to type 1 or type 2 diabetes mellitus. Baseline characteristics were based on those of participants in the RESTORE study. Main outputs were costs (in 2013 CA$) and health outcomes (in quality-adjusted life-years [QALYs]) and the incremental cost-effectiveness ratio (ICER) was calculated. This cost-utility analysis was conducted from healthcare system and societal perspectives in Quebec. Results From a healthcare system perspective, the ICERs for ranibizumab monotherapy and combination therapy vs laser monotherapy were CA$24 494 and CA$36 414 per QALY gained, respectively. The incremental costs per year without legal blindness for ranibizumab monotherapy and combination therapy vs laser monotherapy were CA$15 822 and CA$20 616, respectively. Based on the generally accepted Canadian ICER threshold of CA$50 000 per QALY gained, ranibizumab monotherapy and combination therapy were found to be cost-effective compared with laser monotherapy. From a societal perspective, ranibizumab monotherapy and combination therapy provided greater benefits at lower costs than laser monotherapy (ranibizumab therapy dominated laser therapy). Conclusions Ranibizumab monotherapy and combination therapy resulted in increased quality-adjusted survival and time without legal blindness and lower costs from a societal perspective compared with laser monotherapy.

Can thermal lasers promote skin wound healing?

PubMed

Capon, Alexandre; Mordon, Serge

2003-01-01

Lasers are now widely used for treating numerous cutaneous lesions, for scar revision (hypertrophic and keloid scars), for tissue welding, and for skin resurfacing and remodeling (wrinkle removal). In these procedures lasers are used to generate heat. The modulation of the effect (volatilization, coagulation, hyperthermia) of the laser is obtained by using different wavelengths and laser parameters. The heat source obtained by conversion of light into heat can be very superficial, yet intense, if the laser light is well absorbed (far-infrared:CO(2) or Erbium:Yttrium Aluminum Garnet [Er:YAG] lasers), or it can be much deeper and less intense if the laser light is less absorbed by the skin (visible or near-infrared). Lasers transfer energy, in the form of heat, to surrounding tissues and, regardless of the laser used, a 45-50 degrees C temperature gradient will be obtained in the surrounding skin. If a wound healing process exists, it is a result of live cells reacting to this low temperature increase. The generated supraphysiologic level of heat is able to induce a heat shock response (HSR), which can be defined as the temporary changes in cellular metabolism. These changes are rapid and transient, and are characterized by the production of a small family of proteins termed the heat shock proteins (HSP). Recent experimental studies have clearly demonstrated that HSP 70, which is over-expressed following laser irradiation, could play a role with a coordinated expression of other growth factors such as transforming growth factor (TGF)-beta. TGF-beta is known to be a key element in the inflammatory response and the fibrogenic process. In this process, the fibroblasts are the key cells since they produce collagen and extracellular matrix. In conclusion, the analysis of the literature, and the fundamental considerations concerning the healing process when using thermal lasers, are in favor of a modification of the growth factors synthesis after laser irradiation, induced by an HSR. An extensive review of the different techniques and several clinical studies confirm that thermal lasers could effectively promote skin wound healing, if they are used in a controlled manner.

[Astigmatic keratotomy with the femtosecond laser: correction of high astigmatisms after keratoplasty].

PubMed

Kook, D; Bühren, J; Klaproth, O K; Bauch, A S; Derhartunian, V; Kohnen, T

2011-02-01

The purpose of this study was to evaluate a novel technique for the correction of postoperative astigmatism after penetrating keratoplasty with the use of the femtosecond laser creating astigmatic keratotomies (femto-AK) in the scope of a retrospective case series. Clinical data of ten eyes of nine patients with high residual astigmatism after penetrating keratoplasty undergoing paired femto-AK using a 60-kHz femtosecond laser (IntraLase™, AMO) were analyzed. A new software algorithm was used to create paired arcuate cuts deep into the donor corneal button with different cut angles. Target values were refraction, uncorrected visual acuity, best corrected visual acuity, topographic data (Orbscan®, Bausch & Lomb, Rochester, NY, USA), and corneal wavefront analysis using Visual Optics Lab (VOL)-Pro 7.14 Software (Sarver and Associates). Vector analysis was performed using the Holladay, Cravy and Koch formula. Statistical analysis was performed to detect significances between visits using Student's t test. All procedures were performed without any major complications. The mean follow-up was 13 months. The mean patient age was 48.7 years. The preoperative mean uncorrected visual acuity (logMAR) was 1.27, best corrected visual acuity 0.55, mean subjective cylinder -7.4 D, and mean topometric astigmatism 9.3 D. The postoperative mean uncorrected visual acuity (logMAR) was 1.12, best corrected visual acuity 0.47, mean subjective cylinder -4.1 D, and mean topometric astigmatism 6.5 D. Differences between corneal higher order aberrations showed a high standard deviation and were therefore not statistically significant. Astigmatic keratotomy using the femtosecond laser seems to be a safe and effective tool for the correction of higher corneal astigmatisms. Due to the biomechanical properties of the cornea and missing empirical data for the novel femto-AK technology, higher numbers of patients are necessary to develop optimal treatment nomograms.

Interface Fluid Syndrome After Laser In Situ Keratomileusis (LASIK) Because of Fuchs Endothelial Dystrophy Reversed by Descemet Membrane Endothelial Keratoplasty (DMEK).

PubMed

Luceri, Salvatore; Baksoellah, Zainab; Ilyas, Abbas; Baydoun, Lamis; Melles, Gerrit R J

2016-12-01

To describe a case that developed "interface fluid syndrome" after previous laser in situ keratomileusis (LASIK) because of Fuchs endothelial dystrophy (FED), which was reversed by Descemet membrane endothelial keratoplasty (DMEK). A 58-year-old male patient presented with bilateral visual impairment owing to FED and visually significant cataract. Cataract surgery was carried out in both eyes followed by DMEK in his left eye. After cataract surgery, visual acuity did not improve sufficiently because corneal thickness increased and a fine cleft with interface fluid developed between the LASIK-flap and the residual stromal bed. After uneventful DMEK in his left eye, the fluid resolved within a week and visual acuity improved rapidly. This case demonstrates that "interface fluid syndrome" after LASIK caused by concomitant endothelial dysfunction may be reversed by DMEK allowing fast visual recovery.

Coagulation mechanism of salt solution-extracted active component in Moringa oleifera seeds.

PubMed

Okuda, T; Baes, A U; Nishijima, W; Okada, M

2001-03-01

This study focuses on the coagulation mechanism by the purified coagulant solution (MOC-SC-PC) with the coagulation active component extracted from M. oleifera seeds using salt solution. The addition of MOC-SC-PC tap water formed insoluble matters. This formation was responsible for kaolin coagulation. On the other hand, insoluble matters were not formed when the MOC-SC-PC was added into distilled water. The formation was affected by Ca2+ or other bivalent cations which may connect each molecule of the active coagulation component in MOC-SC-PC and form a net-like structure. The coagulation mechanism of MOC-SC-PC seemed to be an enmeshment of Kaolin by the insoluble matters with the net-like structure. In case of Ca2+ ion (bivalent cations), at least 0.2 mM was necessary for coagulation at 0.3 mgC l-1 dose of MOC-SC-PC. Other coagulation mechanisms like compression of double layer, interparticle bridging or charge neutralization were not responsible for the coagulation by MOC-SC-PC.

Magnetic Resonance Mediated Radio Frequency Coagulation for Vascular Repair

NASA Astrophysics Data System (ADS)

Zhao, Ming

Purpose. Magnetic Resonance Mediated Radiofrequency Coagulation employs the RF heating effect of MRI scanning to coagulate biomaterials for repair of vascular defects. Coagulation of a protein biomaterial by MR-induced RF heating is a novel means to effect repair of defects such as aneurysms or arteriovenous malformations. Our novel method is to coagulate a thermosetting material (such as egg white, which can be used for investigating heat coagulation behavior and MR relaxation properties) delivered endovascularly by catheter and coagulated by RF-induced heating of an intracatheter resonant wire antenna in the scanner. Methods. Experiments were performed on a Siemens 1.5 T MRI scanner and a Bruker 14T NMR spectrometer. Egg white was brought to equilibrium at seven temperatures (20, 30, 40, 50, 60, 70 and 37 °C) in sequence. Measurement of the water spin-lattice relaxation time Ti, spin-spin relaxation time T2, spin-lattice relaxation time in the rotating frame T1p, or full width at half maximum of the MT spectrum were performed at each temperature. Relaxation parameters of raw egg white and egg white after coagulation at 70 °C were measured in the scanner at 20 °C to determine optimum inversion time, echo time and offset frequency for good image contrast between coagulated and uncoagulated protein. Finally, coagulation of egg white within a glass aneurysm phantom by RF heating in the scanner was performed to demonstrate the MR coagulation methodology and the ability to achieve image contrast between coagulated and uncoagulated biomaterial. Results. Water T2, T1p and MT gave the most definitive indication of the change from uncoagulated at low temperature to fully coagulated at 60 °C, while water T1 showed only the expected gradual increase with temperature, and no response to coagulation. MT weighted imaging is expected to be the optimum method to establish the coagulation condition of the biomaterial.

Coagulation monitoring based on blood elastic measurement using optical coherence tomography

NASA Astrophysics Data System (ADS)

Xu, Xiangqun; Zhu, Jiang; Chen, Zhongping

2017-02-01

Blood coagulation monitoring is important to diagnose hematological diseases and cardiovascular diseases and to predict the risk of bleeding and excessive clotting. In this study, we developed a system to dynamically monitor blood coagulation and quantitatively determine the coagulation function by blood elastic measurement. When blood forms a clot from a liquid, ultrasonic force induces a shear wave, which is detected by optical coherence tomography (OCT). The coagulation of porcine whole blood recalcified by calcium chloride is assessed using the metrics of reaction time, clot formation kinetics and maximum shear modulus. The OCE system can noninvasively monitor the blood coagulation and quantitatively determine the coagulation function.

Laser-Assisted Subepithelial Keratectomy versus Laser In Situ Keratomileusis in Myopia: A Systematic Review and Meta-Analysis

PubMed Central

Zhao, Li-Quan; Zhu, Huang; Li, Liang-Mao

2014-01-01

This systematic review was to compare the clinical outcomes between laser-assisted subepithelial keratectomy (LASEK) and laser in situ keratomileusis (LASIK) for myopia. Primary parameters included mean manifest refraction spherical equivalent (MRSE), MRSE within ±0.50 diopters, uncorrected visual acuity (UCVA) ≥20/20, and loss of ≥1 line of best-corrected visual acuity (BCVA). Secondary parameters included flap complications and corneal haze. Twelve clinical controlled trials were identified and used for comparing LASEK (780 eyes) to LASIK (915 eyes). There were no significant differences in visual and refractive outcomes between the two surgeries for low to moderate myopia. The incidence of loss of ≥1 line of BCVA was significantly higher in moderate to high myopia treated by LASEK than LASIK in the mid-term and long-term followup. The efficacy (MRSE and UCVA) of LASEK appeared to be a significant worsening trend in the long-term followup. Corneal haze was more severe in moderate to high myopia treated by LASEK than LASIK in the mid-term and long-term followup. The flap-related complications still occurred in LASIK, but the incidence was not significantly higher than that in LASEK. LASEK and LASIK were safe and effective for low to moderate myopia. The advantage of LASEK was the absence of flap-related complications, and such procedure complication may occur in LASIK and affect the visual results. The increased incidence of stromal haze and regression in LASEK significantly affected the visual and refractive results for high myopia. PMID:24977054

Ex vivo evaluation of super pulse diode laser system with smart temperature feedback for contact soft-tissue surgery

NASA Astrophysics Data System (ADS)

Yaroslavsky, Ilya; Boutoussov, Dmitri; Vybornov, Alexander; Perchuk, Igor; Meleshkevich, Val; Altshuler, Gregory

2018-02-01

Until recently, Laser Diodes (LD) have been limited in their ability to deliver high peak power levels, which, in turn, limited their clinical capabilities. New technological developments made possible advent of "super pulse" LD (SPLD). Moreover, advanced means of smart thermal feedback enable precise control of laser power, thus ensuring safe and optimally efficacious application. In this work, we have evaluated a prototype SPLD system ex vivo. The device provided up to 25 W average and up to 150 W pulse power at 940 nm wavelength. The laser was operated in the thermal feedback-controlled mode, where power of the laser was varied automatically as a function of real-time thermal feedback to maintain constant tip temperature. The system was also equipped with a fiber tip initiated with advanced TiO2 /tungsten technique. Evaluation methods were designed to assess: 1) Speed and depth of cutting; 2) Dimensions of coagulative margin. The SPLD system was compared with industry-leading conventional diode and CO2 devices. The results indicate that the SPLD system provides increase in speed of controlled cutting by a factor of >2 in comparison with the conventional diode laser and approaching that of CO2 device. The produced ratio of the depth of cut to the thermal damage margin was significantly higher than conventional diodes and close to that of the CO2 system, suggesting optimal hemostasis conditions. SPLD technology with real-time temperature control has a potential for creating a new standard of care in the field of precision soft tissue surgery.

Evaluating the speed of visual recovery following thin-flap LASIK with a femtosecond laser.

PubMed

Durrie, Daniel S; Brinton, Jason P; Avila, Michele R; Stahl, Erin D

2012-09-01

To investigate the speed of visual recovery following myopic thin-flap LASIK with a femtosecond laser. This pilot study prospectively evaluated 20 eyes from 10 patients who underwent bilateral simultaneous LASIK with the Femto LDV Crystal Line femtosecond laser (Ziemer Ophthalmic Systems AG) used to create a circular flap of 9.0-mm diameter and 110-μm thickness followed by photoablation with the Allegretto Wave Eye-Q (WaveLight AG) excimer laser. Binocular and monocular uncorrected distance visual acuity (UDVA), monocular contrast sensitivity, and a patient questionnaire were evaluated during the first hours, 1 day, and 1 month postoperatively. For monocular UDVA, 100% of eyes were 20/40 at 1 hour and 100% were 20/25 at 4 hours. For binocular UDVA, all patients achieved 20/32 by 30 minutes and 20/20 by 4 hours. Low frequency contrast sensitivity returned to preoperative baseline by 1 hour (P=.73), and showed a statistically significant improvement over baseline by 4 hours (P=.01). High frequency monocular contrast sensitivity returned to preoperative baseline by 4 hours (P=.48), and showed a statistically significant improvement by 1 month (P=.04). At 2 and 4 hours, 50% and 100% of patients, respectively, indicated that they would feel comfortable driving. Visual recovery after thin-flap femtosecond LASIK is rapid, occurring within the first few hours after surgery. Copyright 2012, SLACK Incorporated.

Fiber-optic-based laser vapor screen flow visualization system for aerodynamic research in larger scale subsonic and transonic wind tunnels

NASA Technical Reports Server (NTRS)

Erickson, Gary E.; Inenaga, Andrew S.

1994-01-01

Laser vapor screen (LVS) flow visualization systems that are fiber-optic based were developed and installed for aerodynamic research in the Langley 8-Foot Transonic Pressure Tunnel and the Langley 7- by 10-Foot High Speed Tunnel. Fiber optics are used to deliver the laser beam through the plenum shell that surrounds the test section of each facility and to the light-sheet-generating optics positioned in the ceiling window of the test section. Water is injected into the wind tunnel diffuser section to increase the relative humidity and promote condensation of the water vapor in the flow field about the model. The condensed water vapor is then illuminated with an intense sheet of laser light to reveal features of the flow field. The plenum shells are optically sealed; therefore, video-based systems are used to observe and document the flow field. Operational experience shows that the fiber-optic-based systems provide safe, reliable, and high-quality off-surface flow visualization in smaller and larger scale subsonic and transonic wind tunnels. The design, the installation, and the application of the Langley Research Center (LaRC) LVS flow visualization systems in larger scale wind tunnels are highlighted. The efficiency of the fiber optic LVS systems and their insensitivity to wind tunnel vibration, the tunnel operating temperature and pressure variations, and the airborne contaminants are discussed.

Schlieren with a laser diode source

NASA Technical Reports Server (NTRS)

Burner, A. W.; Franke, J. M.

1981-01-01

The use of a laser diode as a light source for a schlieren system designed to study phase objects such as a wind-tunnel flow is explored. A laser diode schlieren photograph and a white light schlieren photograph (zirconium arc source) are presented for comparison. The laser diode has increased sensitivity, compared with light schlieren, without appreciable image degradiation, and is an acceptable source for schlieren flow visualization.

Experimental investigation on the vascular thermal response to near-infrared laser pulses.

PubMed

Li, Dong; Chen, Bin; Wu, Wenjuan; Ying, Zhaoxia

2017-12-01

Port wine stains (PWS) are congenital vascular malformations that progressively darken and thicken with age. To improve the effect of laser therapy in clinical practice, thermal response of blood vessel to a 1064 nm Nd:YAG laser with controlled energy doses and pulse durations was evaluated using the dorsal skin chamber model. A total of 137 vessels with 30-300 μm diameters were selected from the dorsal skin of the mouse to match those capillaries in port wine stains. Experimental results showed that the thermal response of blood vessels to 1064 nm laser irradiation can be classified as follows: vessel dilation, coagulation, constriction with decreased diameter, complete constriction, hemorrhage, and collagen damage with increasing laser radiant exposure. In most cases, that is, 83 of 137 blood vessels (60.6%), Nd:YAG laser irradiation was characterized by complete constriction (immediate blood vessel disappearance). To reveal the possible damage mechanisms and evaluate blood vessel photocoagulation patterns, theoretical investigation using bioheat transfer equation was conducted in mouse skin with a depth of 1000 μm. Complete constriction as the dominant thermal response as evidenced by uniform blood heating within the vessel lumen was noted in both experimental observation and theoretical investigation. To achieve the ideal clinical effect using the Nd:YAG laser treatment, the radiant exposure should not only be high enough to induce complete constriction of the blood vessels but also controlled carefully to avoid surrounding collagen damage. The short pulse duration of 1-3 ms is better than long pulse durations because hemorrhaging of small capillaries is occasionally observed postirradiation with pulse durations longer than 10 ms.

Photothermal and photochemical effects of laser light absorption by indocyanine green (ICG)

NASA Astrophysics Data System (ADS)

Yaseen, Mohammad A.; Diagaradjane, Parmeswaran; Pikkula, Brian M.; Yu, Jie; Wong, Michael S.; Anvari, Bahman

2005-04-01

Indocyanine Green (ICG) is clinically used as a fluorescent dye for imaging purposes. Its rapid circulation kinetics and minimal toxicity has prompted investigation into ICG's utility as a photosentitizer for therapeutic applications. Traditionally, optically mediated tumor therapy has focused on photodynamic therapy, which employs a photochemical mechanism resulting from the absorption of low intensity CW laser light by localized photosensitizers such as Photofrin II, Benzoporphyrin Derivative (BPD), ICG. Treatment of cutaneous vascular malformations such as port-wine stains, on the other hand, is based on a photothermal mechanism resulting from the absorption of high intensity pulsed laser light by hemoglobin. In this study, we compared the effectiveness of combining photochemical and photothermal mechanisms during application of ICG in conjunction with laser irradiation with the intention that the combined approach may lead to a reduction in the threshold dose of pulsed laser light required to treat hypervascular malformations. The blood vessels in rabbit ears were used as an in vivo model for targeted vasculature. Irradiation of the ears with IR light (λ=785 nm, Δτ = 3 min, Io = 120 mW) was used to elicit photochemical damage, while photothermal damage was brought about using pulses from a ruby laser (λ=694 nm, τ = 3 ms) with different fluences. For the combined modality, photochemical damage was induced first and followed by photothermal irradiation. This modality was compared with photothermal irradiation alone. The effectiveness of each irradiation scheme was assessed using histopathological analysis. We present preliminary data that suggests that pretreatment with photodynamic therapy before photothermal coagulation results in more severe vascular damage with lower photothermal fluence levels. The results of this study provide the foundation work for further exploration of the therapeutic potentials of photochemical and photothermal effects during application of ICG in conjunction with laser irradiation.

Laser Capture Microdissection for Protein and NanoString RNA analysis

PubMed Central

Golubeva, Yelena; Salcedo, Rosalba; Mueller, Claudius; Liotta, Lance A.; Espina, Virginia

2013-01-01

Laser capture microdissection (LCM) allows the precise procurement of enriched cell populations from a heterogeneous tissue, or live cell culture, under direct microscopic visualization. Histologically enriched cell populations can be procured by harvesting cells of interest directly, or isolating specific cells by ablating unwanted cells. The basic components of laser microdissection technology are a) visualization of cells via light microscopy, b) transfer of laser energy to a thermolabile polymer with either the formation of a polymer-cell composite (capture method) or transfer of laser energy via an ultraviolet laser to photovolatize a region of tissue (cutting method), and c) removal of cells of interest from the heterogeneous tissue section. The capture and cutting methods (instruments) for laser microdissection differ in the manner by which cells of interest are removed from the heterogeneous sample. Laser energy in the capture method is infrared (810nm), while in the cutting mode the laser is ultraviolet (355nm). Infrared lasers melt a thermolabile polymer that adheres to the cells of interest, whereas ultraviolet lasers ablate cells for either removal of unwanted cells or excision of a defined area of cells. LCM technology is applicable to an array of applications including mass spectrometry, DNA genotyping and loss-of-heterozygosity analysis, RNA transcript profiling, cDNA library generation, proteomics discovery, and signal kinase pathway profiling. This chapter describes laser capture microdissection using an ArcturusXT instrument for protein LCM sample analysis, and using a mmi CellCut Plus® instrument for RNA analysis via NanoString technology. PMID:23027006

Visualization of removal of trapped air from the apical region in simulated root canals by laser-activated irrigation using an Er,Cr:YSGG laser.

PubMed

Peeters, Harry Huiz; De Moor, Roeland J G; Suharto, Djoko

2015-08-01

The aim of this visualization study was to obtain a better understanding of the mechanism by which trapped air is removed from the apical region of simulated root canals by activation of an irrigant using an erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser during endodontic procedures. A high-speed imaging system with high temporal and spatial resolution was used to visualize laser-induced shock waves in a resin block model with a curved root canal (inner diameter at the apex 0.08 mm, taper 4 %, crown height 10 mm, overall length 40 mm) and a glass cylinder model with a straight root canal (inner diameter 1 mm, crown height 10 mm, overall length 40 mm). The study utilized MZ3 and RFT3 tips in each model, without water or air spray, and with an average power of 1 W at 35 Hz. Laser-activated irrigation overcame the airlock effect by releasing air trapped in the air column. The mechanism underlying the removal of trapped air from the apical region using an Er,Cr:YSGG laser in a dry root canal is via the disruption of the surface tension at the solution-air interface. This disruption, caused by bubble implosion (cavitation), displaces air in the form of bubbles from the apical region toward the solution, which allows the solution to travel apically.

Lasers' spectral and temporal profile can affect visual glare disability.

PubMed

Beer, Jeremy M A; Freeman, David A

2012-12-01

Experiments measured the effects of laser glare on visual orientation and motion perception. Laser stimuli were varied according to spectral composition and temporal presentation as subjects identified targets' tilt (Experiment 1) and movement (Experiment 2). The objective was to determine whether the glare parameters would alter visual disruption. Three spectral profiles (monochromatic Green vs. polychromatic White vs. alternating Red-Green) were used to produce a ring of laser glare surrounding a target. Two experiments were performed to measure the minimum contrast required to report target orientation or motion direction. The temporal glare profile was also varied: the ring was illuminated either continuously or discontinuously. Time-averaged luminance of the glare stimuli was matched across all conditions. In both experiments, threshold (deltaL) values were approximately 0.15 log units higher in monochromatic Green than in polychromatic White conditions. In Experiment 2 (motion identification), thresholds were approximately 0.17 log units higher in rapidly flashing (6, 10, or 14 Hz) than in continuous exposure conditions. Monochromatic extended-source laser glare disrupted orientation and motion identification more than polychromatic glare. In the motion task, pulse trains faster than 6 Hz (but below flicker fusion) elevated thresholds more than continuous glare with the same time-averaged luminance. Under these conditions, alternating the wavelength of monochromatic glare over time did not aggravate disability relative to green-only glare. Repetitively flashing monochromatic laser glare induced occasional episodes of impaired motion identification, perhaps resulting from cognitive interference. Interference speckle might play a role in aggravating monochromatic glare effects.

Particle counter as a tool to control pre-hydrolyzed coagulant dosing and rapid filtration efficiency in a conventional treatment system.

PubMed

Gumińska, Jolanta; Kłos, Marcin

2015-01-01

Filtration efficiency in a conventional water treatment system was analyzed in the context of pre-hydrolyzed coagulant overdosing. Two commercial coagulants of different aluminum speciation were tested. A study was carried out at a water treatment plant supplied with raw water of variable quality. The lack of stability of water quality caused many problems with maintaining the optimal coagulant dose. The achieved results show that the type of coagulant had a very strong influence on the effectiveness of filtration resulting from the application of an improper coagulant dose. The overdosing of high basicity coagulant (PAC85) caused a significant increase of fine particles in the outflow from the sedimentation tanks, which could not be retained in the filter bed due to high surface charge and the small size of hydrolysis products. When using a coagulant of lower basicity (PAC70), it was much easier to control the dose of coagulant and to adjust it to the changing water quality.

Chemical coagulation of combined sewer overflow: heavy metal removal and treatment optimization.

PubMed

El Samrani, A G; Lartiges, B S; Villiéras, F

2008-02-01

The coagulation of combined sewer overflow (CSO) was investigated by jar-testing with two commercial coagulants, a ferric chloride solution (CLARFER) and a polyaluminium chloride (WAC HB). CSO samples were collected as a function of time during various wet-weather events from the inlet of Boudonville retention basin, Nancy, France. Jar-tests showed that an efficient turbidity removal can be achieved with both coagulants, though lower optimum dosages and higher re-stabilization concentrations were obtained with the aluminum-based coagulant. Optimum turbidity removal also yielded effective heavy metal elimination. However, the evolution with coagulant dosage of Cu, Zn, Pb, Cr, soluble and suspended solids contents followed various patterns. The removal behaviors can be explained by a selective aggregation of heavy metal carriers present in CSO and a specific interaction between hydrolyzed coagulant species and soluble metals. Stoichiometric relationships were established between optimal coagulant concentration, range of optimal dosing, and CSO conductivity, thus providing useful guidelines to adjust the coagulant demand during the course of CSO events.

Optoacoustic online temperature determination during retinal laser photocoagulation

NASA Astrophysics Data System (ADS)

Schlott, Kerstin; Stalljohann, Jens; Weber, Benjamin; Kandulla, Jochen; Herrmann, Katharina; Birngruber, Reginald; Brinkmann, Ralf

2007-07-01

Retinal photocoagulation is an established treatment of different retinal diseases. The treatment relies on a short, local heating of the tissue which induces a denaturation. The resulting scar formation may for example prevent the further detachment of the retina. The extent of the coagulation is besides other parameters mostly dependent on the induced temperature increase. However, until today a temperature based dosimetry for photocoagulation does not exist. The dosage is rather based on the experience of the treating physicians to achieve visible whitish lesions on the retina. In this work a technique is presented, which allows an online temperature monitoring during photocoagulation. If an absorbing material is irradiated with short laser pulses, a thermoelastic expansion of the absorber induces an acoustic wave. Its amplitude is dependent on the temperature of the absorber. For analyzing the applicability of the optoacoustic temperature determination for dosimetry, measurements were performed on enucleated porcine eye globes. The pressure transients are detected by an ultrasonic transducer, which is embedded in an ophthalmologic contact lens. As long as no strong lesions occur, the determined temperatures are almost proportional to the power of the treatment laser. Using a spot diameter of 200 μm and different laser powers, the temperature rise at the end of the 400 ms irradiation was found to be approximately 0.16 °C/mW. The onset of the denaturation was observed around 50°C. The far aim of this project is an automatic regulation of the treatment laser onto a desired temperature course.

Selective nanoparticle-directed photothermal ablation of the canine prostate

NASA Astrophysics Data System (ADS)

Schwartz, Jon A.; Price, Roger E.; Gill-Sharp, Kelly L.; Sang, Krystina L.; Khorchani, Jennifer D.; Payne, J. Donald; Goodwin, Bradford S.

2011-03-01

This study adapted AuroLase® Therapy, previously reported for the treatment of brain tumors, to the treatment of prostate disease by 1) using normal canine prostate in vivo, directly injected with a solution of nanoparticles as a proxy for prostate tumor and, 2) developing an appropriate laser dosimetry for prostate which is which is subablative in native prostate while simultaneously producing photothermal coagulation in prostate tissue containing therapeutic nanoshells. Healthy, mixed-breed hound dogs were given surgical laparotomies during which nanoshells were injected directly into one or both prostate hemispheres. Laser energy was delivered percutaneously to the parenchyma of the prostate along 1-5 longitudinal tracts via a liquid-cooled optical fiber catheter terminated with a 1-cm isotropic diffuser after which the incision was closed and sutured using standard surgical techniques. The photothermal lesions were permitted to resolve for up to 8 days, after which each animal was euthanized, necropsied, and the prostate taken for histopathological analysis. We developed a laser dosimetry which is sub- to marginally ablative in native prostate and simultaneously ablative of prostate tissue containing nanoshells which would indicate a viable means of treating tumors of the prostate which are known from other studies to accumulate nanoshells. Secondly, we determined that multiple laser treatments of nanoshell-containing prostate tissue could be accomplished while sparing the urethra and prostate capsule thermal damage. Finally, we determined that the extent of damage zone radii correlate positively with nanoshell concentration, and negatively to the length of time between nanoshell injection and laser treatment.

Low-power interstitial photocoagulation of uterine leiomyomas by KTP/YAG laser: a review of 50 consecutive cases

NASA Astrophysics Data System (ADS)

Chapman, Roxana

1994-12-01

Interstitial laser photocoagulation (ILP), which is a new method of low power laser destruction of tumors, has been used to treat laparoscopically 50 consecutive patients with symptomatic uterine leiomyomas which were difficult or impossible to remove via laparoscopy. The KTP/YAG laser, with wavelengths of 532 and 1064 nm respectively, was employed. Holes 2 cm apart were drilled with a 600 micrometers quartz laser fiber employing the KTP component at 8 W and subsequent coagulation of the surrounding myoma tissue was accomplished during the withdrawal of the fiber over the course of 10 - 30 s but using the YAG component at 8 W until the whole myoma had been treated. Thirty seven became symptom free and have remained so. Six were lost to follow up. Of 10 complaining of subfertility 4, in whom uterine myomas were the only etiological factor, have become pregnant. Seven patients required further treatment: Two were retreated because their myomas were excessively large and did not completely disappear with the initial ILP, 2 received further ILP because of the development of new myomas and 3 were subjected to laparoscopically assisted vaginal hysterectomy at patients' request (2 because of the development of new myomas and 1 because of the development of further endometriosis). Finally, in 7 cases, residual tumor or scar tissue was biopsied and examined for the presence of oestrogen and progesterone receptors. None was discovered and in 2 subsequent pregnancy did not cause further growth of residual myoma tissue.

Ways of Noninvasive Facial Skin Tightening and Fat Reduction.

PubMed

Fritz, Klaus; Salavastru, Carmen

2016-06-01

For skin tightening, ablative and nonablative lasers have been used with various parameters full or fractionated. Currently, other energy-based technologies have been developed such as radiofrequency (RF) from mono- to multipolar, microneedling RF, and high-intensity focused ultrasound. They heat up the tissue to a clinical endpoint. Temperatures above 42°C stimulate fibroblasts to produce more collagen and some technologies produce small coagulation points that allow to shrink and to tighten the tissue with less downtime or side effects. Alternative treatments not based on heat can be chemical peels from light to deep and microneedling without RF. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Laser capture microdissection: Arcturus(XT) infrared capture and UV cutting methods.

PubMed

Gallagher, Rosa I; Blakely, Steven R; Liotta, Lance A; Espina, Virginia

2012-01-01

Laser capture microdissection (LCM) is a technique that allows the precise procurement of enriched cell populations from a heterogeneous tissue under direct microscopic visualization. LCM can be used to harvest the cells of interest directly or can be used to isolate specific cells by ablating the unwanted cells, resulting in histologically enriched cell populations. The fundamental components of laser microdissection technology are (a) visualization of the cells of interest via microscopy, (b) transfer of laser energy to a thermolabile polymer with either the formation of a polymer-cell composite (capture method) or transfer of laser energy via an ultraviolet laser to photovolatize a region of tissue (cutting method), and (c) removal of cells of interest from the heterogeneous tissue section. Laser energy supplied by LCM instruments can be infrared (810 nm) or ultraviolet (355 nm). Infrared lasers melt thermolabile polymers for cell capture, whereas ultraviolet lasers ablate cells for either removal of unwanted cells or excision of a defined area of cells. LCM technology is applicable to an array of applications including mass spectrometry, DNA genotyping and loss-of-heterozygosity analysis, RNA transcript profiling, cDNA library generation, proteomics discovery, and signal kinase pathway profiling. This chapter describes the unique features of the Arcturus(XT) laser capture microdissection instrument, which incorporates both infrared capture and ultraviolet cutting technology in one instrument, using a proteomic downstream assay as a model.

Prenatal Therapy of Large Placental Chorioangiomas: Case Report and Review of the Literature

PubMed Central

Hosseinzadeh, Pardis; Shamshirsaz, Alireza A.; Javadian, Pouya; Espinoza, Jimmy; Gandhi, Manisha; Ruano, Rodrigo; Cass, Darrell L.; Olutoye, Oluyinka A.; Belfort, Michael A.

2015-01-01

Objective To review techniques and outcomes of different prenatal treatments for large placental chorioangiomas. Study Design Presentation of a case of laparoscopic-assisted laser coagulation and a systematic review of the literature for articles related to intervention for placental chorioangioma. Results A total of 37 cases of definitive (n = 23) and supportive therapy (n = 14) were evaluated, including one case treated in our center. Approximately 35% of the patients had a spontaneous preterm delivery in definitive treatment group versus 36% in the supportive group. The infant survival rates were 65 and 71% in the two groups, respectively. We further compared the two types of laser ablation (fetoscopic [n = 10] and interstitial [n = 4]). Approximately 30% of the patients in the fetoscopic and 25% in interstitial group, had a spontaneous preterm delivery. Survival rates were 60 and 100% in fetoscopic and interstitial groups, respectively. Conclusion Laser ablation and embolization of chorioangiomas via minimally invasive approach may prevent or reverse fetal hydrops due to high cardiac states. However, further studies are needed to refine the appropriate selection criteria that will justify the risk of this invasive in utero therapy for chorioangiomas. PMID:26495184

Microperimetry and fundus autofluorescence in diabetic macular edema: subthreshold micropulse diode laser versus modified early treatment diabetic retinopathy study laser photocoagulation.

PubMed

Vujosevic, Stela; Bottega, Elisa; Casciano, Margherita; Pilotto, Elisabetta; Convento, Enrica; Midena, Edoardo

2010-06-01

The purpose of this study was to evaluate and compare microperimetry and fundus autofluorescence (FAF) after subthreshold micropulse diode laser versus modified Early Treatment Diabetic Retinopathy Study photocoagulation for clinically significant diabetic macular edema. A prospective randomized clinical trial including 62 eyes (50 patients) with untreated, center-involving, clinically significant diabetic macular edema was performed. All patients underwent best-corrected visual acuity determination (logarithm of the minimum angle of resolution), slit-lamp biomicroscopy, FAF, optical coherence tomography, microperimetry (macular sensitivity), and fluorescein angiography before and after treatment. Best-corrected visual acuity, optical coherence tomography, microperimetry, and FAF were repeated at 1-, 3-, 6-, 9-, and 12-month follow-up examinations. Fluorescein angiography was performed at baseline and at 6 and 12 months. Before treatment, demographic and macular parameters were not different between the two treatment groups. At 12 months, best-corrected visual acuity remained stable in both groups (P = 0.41 and P = 0.82), mean central retinal thickness decreased in both groups (P = 0.0002 and P < 0.0001), and mean central 4 degrees and 12 degrees retinal sensitivity increased in the micropulse diode laser group (P = 0.02 and P = 0.0075) and decreased in the Early Treatment Diabetic Retinopathy Study group (P = 0.2 and P = 0.0026). There was no significant difference in either best-corrected visual acuity or central retinal thickness between the 2 treatment groups (P = 0.48 and P = 0.29), whereas there was a significant difference in 4 degrees and 12 degrees retinal sensitivity (P = 0.04 and P < 0.0001). Fundus autofluorescence never changed in the micropulse diode laser group even after retreatment. In the Early Treatment Diabetic Retinopathy Study group, FAF increased up to 9 months and decreased in 6 eyes (20%) at 12 months. Micropulse diode laser seems to be as effective as modified Early Treatment Diabetic Retinopathy Study laser photocoagulation in the treatment of clinically significant diabetic macular edema. Micropulse diode laser treatment does not determine any change on FAF showing (at least) nonclinically visible damage of the retinal pigment epithelium. Microperimetry data encourage the use of a new, less aggressive laser therapeutic approach in the treatment of clinically significant diabetic macular edema.

[Water-cooled laser sealing of lung tissue in an ex-vivo ventilated porcine lung model].

PubMed

Tonoyan, T; Prisadov, G; Menges, P; Herrmann, K; Bobrov, P; Linder, A

2014-06-01

Laser resections of lung metastases are followed by air leaks from the parenchymal defect. Large surfaces after metastasectomy are closed by sutures or sealants while smaller areas are frequently sealed thermally by cautery or laser. In this study two different techniques of thermal sealing of lung tissue with laser light are investigated. Carbonisation of lung tissue during thermal sealing appears at temperatures higher than 180 °C. Hypothetically this is contraproductive to haemo- as well as to pneumostasis. In this experimental study thermal laser sealing with and without carbonisation is investigated. In one series tissue temperatures higher than 100 °C are avoided by water dropping from the tip of the light guide onto the parenchymal leak. In the other series carbonisation appeared because the laser light was applied in the non-contact mode without tissue cooling. The characteristics of the laser were 40 W, 1350 nm continuous mode. Air leaks (Vt) were measured with a simple and fast technique with high precision. The sealing effect of either series was defined as S = (1-Vt/V0) and the difference of S was statistically examined. The basic values V0 before sealing were about the same in both series. The air leaks Vt after 15, 30 and 45 s of sealing varied significantly in both series (p = 0.03). During simultaneous cooling the sealing effect was increasing with the duration of laser application, while it became worse in the series without cooling. Histological examination of the sealing zone showed only coagulation of the tissue, while ruptured alveolae could be seen more often in the non-cooled sealing area. It could be shown in the ex-vivo lung model that laser sealing of parenchymal leaks is improved by simultaneous cooling during laser application. Non cooled laser sealing seems to heat up the tissue abruptly and create carbonisation followed by multiple ruptures of alveola and small airways. In accordance with our clinical experience this experimental study confirms that laser sealing for pneumostasis after metastasectomy can be improved by simultaneously cooling the resection area when treated with the laser. Georg Thieme Verlag KG Stuttgart · New York.

Physics of light and lasers.

PubMed

Absten, G T

1991-09-01

Because most laser procedures use the heating effect of the light and given the number of parameters that may be varied--such as power density, power, pulsing, and heating of fiber tips and probes--significant overlap in applications of the various lasers can result. This is readily apparent in the conflicting claims of laser manufacturers seen in promotional materials. Despite this, each type has its strengths. The CO2 laser is a specialty instrument, particularly for microscopic applications in neurosurgery, otolaryngology, and gynecology. Its hemostasis and vaporizing abilities allow its use in dermatology and in general surgery for tumor resection and hemostasis. In gynecology it seems best for colposcopy (cervical and vaginal) and, through a micromanipulator, for laparotomy. The beam is focused and delivered by handpieces and micromanipulators on microscopes. Through the laparoscope, it requires the use of a special laser coupler on a special laser laparoscope to allow for line-of-sight delivery of the beam through the operating channel. Waveguide delivery systems have been introduced for CO2 laser laparoscopy using standard laparoscopes. These function as hollow, slender tubes through which the beam is transmitted by means of hundreds of glancing internal reflections in the tube, which emits the beam at its tip. This eliminates many of the alignment problems of coupler cube-type systems and allows the beam to be delivered close to the target. The Nd:YAG laser is the primary endoscopic instrument in pulmonology, gastroenterology, and urology. The use of contact tips, though not a panacea, increases its applications, particularly in general surgery. Its primary use in gynecology is for endometrial ablation with bare fibers for deep coagulation. Its use for laparoscopy with contact probes or sculpted fibers is quickly growing. Green light lasers (argon and KTP) are color-selective photocoagulators and may be used to cut tissue. They are fiberoptically delivered like the Nd:YAG laser. Their best use in gynecology appears to be a versatile instruments for operative laparoscopy and the simple treatment of endometriosis. A standard quartz fiber with these lasers is usually more versatile than a contact tip with an Nd:YAG laser when used for cutting.

Optical thromboelastography (OTEG) for diagnosis of hyperfibrinolysis in patients (Conference Presentation)

NASA Astrophysics Data System (ADS)

Tripathi, Markandey M.; Tshikudi, Diane M.; Nadkarni, Seemantini K.

2016-03-01

Fibrinolysis is a process that regulates the breakdown of a blood clot to enable wound healing and is an essential component of hemostasis. Abnormalities in the fibrinolysis pathway may cause hyperfibrinolysis, associated with the increased risk of life-threatening bleeding particularly following acute trauma or major surgery. Assessing fibrinolytic activity in bleeding patients at the bedside can enable the timely administration of fibrinolysis inhibitors to improve prognosis. Optical thromboelastography (OTEG), a novel technique to assess blood coagulation status, has the potential to quantify fibrinolysis in real-time at PoC. The goal of the current study is to test the accuracy of OTEG in quantifying fibrinolytic status of human blood. Fibrinolysis is activated by adding varying concentrations of tissue plasminogen activator (tPA), a known fibrinolysis activator. The blood sample is illuminated by laser light and the resultant speckle intensity autocorrelation curve is used to derive changes in clot viscoelastic modulus during coagulation. From the OTEG trace, the coagulation parameters, clotting time (R), clot progression time (K), maximum clot strength (MA), and clot lysis (LY%) are derived. Our results indicate that increased tPA (0-0.5μM/ml) activation causes dose-dependent increase in LY% measured with OTEG: For instance, the addition of 0.5μM/ml of tPA increased LY% from 14.0 % to 81.5%. OTEG measurements also show a strong correlation with standard-reference mechanical Thromboelastography (TEG) measurements (N = 15, R=0.87, p<0.05). These results demonstrate that OTEG can accurately evaluate fibrinolysis and may provide the capability for identifying hyperfibrinolytic patients at an increased risk of life-threatening hemorrhage.

Optical profiling of anticoagulation status (Conference Presentation)

NASA Astrophysics Data System (ADS)

Tshikudi, Diane M.; Tripathi, Markandey M.; Hajjarian, Zeinab; Nadkarni, Seemantini K.

2016-02-01

Defective blood coagulation resulting from excessive procoagulant activity often leads to thrombotic disorders such as stroke and myocardial infarction. A variety of oral and injectable anticoagulant drugs are prescribed to prevent or treat life-threatening thrombosis. However, due to bleeding complications often associated with anticoagulant treatment, routine monitoring and accurate dosing of anticoagulant therapy is imperative. We have developed Optical thromboelastography (OTEG), a non-contact approach that utilizes a drop of whole blood to measure blood coagulation status in patients. Here, we demonstrate the capability of OTEG for rapidly monitoring anticoagulation in whole blood samples. OTEG monitors coagulation status by assessing changes in blood viscosity from temporal intensity fluctuations of laser speckle patterns during clotting. In OTEG a blood drop is illuminated with coherent light and the blood viscosity is measured from the speckle intensity autocorrelation curve, g2 (t). The metrics, clotting time (R+k), clot progression (angle) and maximum clot stiffness (MA) are then extracted. The aim of the current study was to evaluate the accuracy of OTEG in assessing anticoagulation status of common anticoagulants including heparin, argatroban and rivaroxaban status. A dose-dependent prolongation of R+k was observed in anticoagulated blood, which closely corresponded with standard-reference Thromboelastography (TEG) (r 0.87-0.99, P>0.01 for all cases). OTEG angle was unaltered by anticoagulation whereas TEG angle presented a dose-dependent diminution probably linked to clot rupture. In both OTEG and TEG, MA was unaffected by heparin, argatroban or rivaroxaban. We conclude that OTEG can accurately monitor anticoagulation status following treatment, potentially providing a powerful tool for routine monitoring of patients in the doctor's office or in the home setting.

Diode laser for abdominal tissue cauterization

NASA Astrophysics Data System (ADS)

Durville, Frederic M.; Rediker, Robert H.; Connolly, Raymond J.; Schwaitzberg, Steven D.; Lantis, John

1999-06-01

We have developed a new device to effectively and quickly stop bleeding. The new device uses a small, 5 W diode laser to heat-up the tip of a modified medical forceps. The laser beam is totally contained within a protective enclosure, satisfying the requirements for a Class I laser system, which eliminates the need to protective eyewear. The new device is used in a manner similar to that of a bipolar electrocautery device. After visual location, the bleeding site or local vessel(s) is grabbed and clamped with the tips of the forceps-like instrument. The laser is then activated for a duration of typically 5 sec or until traditional visual or auditory clues such as local blubbling and popping indicate that the targeted site is effectively cauterized. When the laser is activated, the tip of the instrument, thus providing hemostasis. The new device was evaluated in animal models and compared with the monopolar and bipolar electrocautery, and also with the recently developed ultrasound technology. It has new been in clinical trials for abdominal surgery since September 1997.

Solid colloidal optical wavelength filter

DOEpatents

Alvarez, Joseph L.

1992-01-01

A solid colloidal optical wavelength filter includes a suspension of spheal particles dispersed in a coagulable medium such as a setting plastic. The filter is formed by suspending spherical particles in a coagulable medium; agitating the particles and coagulable medium to produce an emulsion of particles suspended in the coagulable medium; and allowing the coagulable medium and suspended emulsion of particles to cool.

Application of Cox model in coagulation function in patients with primary liver cancer.

PubMed

Guo, Xuan; Chen, Mingwei; Ding, Li; Zhao, Shan; Wang, Yuefei; Kang, Qinjiong; Liu, Yi

2011-01-01

To analyze the distribution of coagulation parameters in patients with primary liver cancer; explore the relationship between clinical staging, survival, and coagulation parameters by using Coxproportional hazard model; and provide a parameter for clinical management and prognosis. Coagulation parameters were evaluated in 228 patients with primary liver cancer, 52 patients with common liver disease, and 52 normal healthy controls. The relationship between primary livercancer staging and coagulation parameters wasanalyzed. Follow-up examinations were performed. The Cox proportional hazard model was used to analyze the relationship between coagulationparameters and survival. The changes in the coagulation parameters in patients with primary liver cancer were significantly different from those in normal controls. The effect of the disease on coagulation function became more obvious as the severity of liver cancer increased (p<0.05). The levels of D-dimer, fibrinogen degradation products (FDP), fibrinogen (FIB), and platelets (PLT) were negatively correlated with the long-term survival of patients with advanced liver cancer. The stages of primary liver cancer are associated with coagulation parameters. Coagulation parameters are related to survival and risk factors. Monitoring of coagulation parameters may help ensure better surveillance and treatment for liver cancer patients.

Monopolar soft-mode coagulation using hemostatic forceps for peptic ulcer bleeding.

PubMed

Yamasaki, Yasushi; Takenaka, Ryuta; Nunoue, Tomokazu; Kono, Yoshiyasu; Takemoto, Koji; Taira, Akihiko; Tsugeno, Hirofumi; Fujiki, Shigeatsu

2014-01-01

Upper gastrointestinal hemorrhage from bleeding peptic ulcer is sometimes difficult to treat by conventional endoscopic methods. Recently, monopolar electrocoagulation using a soft-coagulation system and hemostatic forceps (soft coagulation) has been used to prevent bleeding during endoscopic submucosal dissection. The aim of this study was to assess the safety and efficacy of soft coagulation in the treatment of bleeding peptic ulcer. A total of 39 patients with peptic ulcers were treated using soft coagulation at our hospital between January 2005 and March 2010. Emergency treatment employed an ERBE soft-mode coagulation system using hemostatic forceps. Second-look endoscopy was performed to evaluate the efficacy of prior therapy. Initial hemostasis was defined as accomplished by soft coagulation, with or without other endoscopic therapy prior to soft coagulation. The rate of initial hemostasis, rebleeding, and ultimate hemostasis were retrospectively analyzed. The study subjects were 31 men and 8 women with a mean age of 68.3±13.7 years, with 29 gastric ulcers and 10 duodenal ulcers. Initial hemostasis was achieved in 37 patients (95%). During follow-up, bleeding recurred in two patients, who were retreated with soft coagulation. The monopolar soft coagulation is feasible and safe for treating bleeding peptic ulcers.

Direct observation on the Brownian coagulation of PSL particles through optical microscope in the regime near critical coagulation concentration (CCC).

PubMed

Fukasawa, Tomonori; Adachi, Yasuhisa

2010-04-15

Microscopic monitoring of floc structure, floc size distribution and the rate of coagulation was carried out for Brownian coagulation of PSL particles. Experiments were designed for the condition of salt concentration that is slightly below critical coagulation concentration (CCC). The density of the solvent was controlled by using deuterium oxide (D(2)O) to avoid sedimentation. Results are summarized as follows: (i) Near CCC, floc restructuring from the beginning stage of coagulation was evidenced, i.e., the ratio of linear triplet is found to be remarkably reduced as compared with the result obtained for the case of rapid coagulation which was implemented under sufficiently high salt concentration. (ii) The increase of fractal dimension from 1.8 in the case of rapid coagulation to 2.2 was confirmed by the analysis of mass balance using size distribution of flocs. This increment resulted in the decrease of effective excluded volume of flocs. (iii) The rate of coagulation was constant until later stage. This result contrasts to the result of rapid coagulation [T. Fukasawa, Y. Adachi, J. Colloid Interface Sci. 304 (2006) 115]. 2010 Elsevier Inc. All rights reserved.

Protective effect of basic fibroblast growth factor on retinal injury induced by argon laser photocoagulation

NASA Astrophysics Data System (ADS)

Chen, P.; Zhang, C. P.; San, Q.; Wang, C. Z.; Yang, Z. F.; Kang, H. X.; Qian, H. W.

2010-12-01

Laser photocoagulation treatment is often complicated by a side effect of visual impairment, which is caused by the unavoidable laser-induced retinal destruction. At present no specific is found to cure this retinopathy. The aim of this study was to observe the neuroprotective effect of bFGF on laser-induced retinal injury. Chinchilla rabbits were divided into three groups and argon laser lesions were created in the retinas. Then bFGF or dexamethasone, a widely used ophthalmic preparation, or saline was given severally by retrobulbar injection. The retinal lesions were evaluated histologically and morphometrically, and visual function was examined by ERG. The results showed that bFGF administration better preserved morphology of retinal photoreceptors and significantly diminished the area of the lesions. Furthermore, bFGF promoted the restoration of the ERG b-wave amplitude. In rabbits treated with dexamethasone, however, the lesions showed almost no ameliorative changes. This is the first study to investigate the potential role of bFGF as a remedial agent in laser photocoagulation treatment. These findings suggest that bFGF has significant neuroprotective properties in the retina and this type of neuroprotection may be of clinical significance in reducing iatrogenic laser-induced retinal injuries in humans.