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Journal articles on the topic 'Laser ablation'

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Published: 4 June 2021
Last updated: 8 June 2024

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1

Munier, Sean M., Eric L. Hargreaves, Nitesh V. Patel, and Shabbar F. Danish. "Ablation dynamics of subsequent thermal doses delivered to previously heat-damaged tissue during magnetic resonance–guided laser-induced thermal therapy." Journal of Neurosurgery 131, no. 6 (December 2019): 1958–65. http://dx.doi.org/10.3171/2018.7.jns18886.

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OBJECTIVEIntraoperative dynamics of magnetic resonance–guided laser-induced thermal therapy (MRgLITT) have been previously characterized for ablations of naive tissue. However, most treatment sessions require the delivery of multiple doses, and little is known about the ablation dynamics when additional doses are applied to heat-damaged tissue. This study investigated the differences in ablation dynamics between naive versus damaged tissue.METHODSThe authors examined 168 ablations from 60 patients across various surgical indications. All ablations were performed using the Visualase MRI-guided laser ablation system (Medtronic), which employs a 980-nm diffusing tip diode laser. Cases with multiple topographically overlapping doses with constant power were selected for this study. Single-dose intraoperative thermal damage was used to calculate ablation rate based on the thermal damage estimate (TDE) of the maximum area of ablation achieved (TDEmax) and the total duration of ablation (tmax). We compared ablation rates of naive undamaged tissue and damaged tissue exposed to subsequent thermal doses following an initial ablation.RESULTSTDEmax was significantly decreased in subsequent ablations compared to the preceding ablation (initial ablation 227.8 ± 17.7 mm2, second ablation 164.1 ± 21.5 mm2, third ablation 124.3 ± 11.2 mm2; p = < 0.001). The ablation rate of subsequent thermal doses delivered to previously damaged tissue was significantly decreased compared to the ablation rate of naive tissue (initial ablation 2.703 mm2/sec; second ablation 1.559 mm2/sec; third ablation 1.237 mm2/sec; fourth ablation 1.076 mm/sec; p = < 0.001). A negative correlation was found between TDEmax and percentage of overlap in a subsequent ablation with previously damaged tissue (r = −0.164; p < 0.02).CONCLUSIONSAblation of previously ablated tissue results in a reduced ablation rate and reduced TDEmax. Additionally, each successive thermal dose in a series of sequential ablations results in a decreased ablation rate relative to that of the preceding ablation. In the absence of a change in power, operators should anticipate a possible reduction in TDE when ablating partially damaged tissue for a similar amount of time compared to the preceding ablation.
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2

Munier, Sean M., Allison S. Liang, Akshay N. Desai, Jose K. James, and Shabbar F. Danish. "Characterization of Magnetic Resonance Thermal Imaging Signal Artifact During Magnetic Resonance Guided Laser-Induced Thermal Therapy." Operative Neurosurgery 19, no. 5 (July 31, 2020): 619–24. http://dx.doi.org/10.1093/ons/opaa229.

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Abstract BACKGROUND Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) is a minimally invasive procedure that utilizes intraoperative magnetic resonance thermal imaging (MRTI) to generate a thermal damage estimate (TDE) of the ablative area. In select cases, the MRTI contains a signal artifact or defect that distorts the ablative region. No study has attempted to characterize this artifact. OBJECTIVE To characterize MRTI signal the artifact in select cases to better understand its potential relevance and impact on the ablation procedure. METHODS All ablations were performed using the Visualase magnetic resonance imaging-guided laser ablation system (Medtronic). Patients were included if the MRTI contained signal artifact that distorted the ablative region during the first thermal dose delivered. Ablation artifact was quantified using MATLAB version R2018a (Mathworks Inc, Natick, Massachusetts). RESULTS A total of 116 patients undergoing MRgLITT for various surgical indications were examined. MRTI artifact was observed in 37.0% of cases overall. Incidence of artifact was greater at higher powers (P &lt; .001) and with longer ablation times (P = .024), though artifact size did not correlate with laser power or ablation duration. CONCLUSION MRTI signal artifact is common during LITT. Higher powers and longer ablation times result in greater incidence of ablation artifact, though artifact size is not correlated with power or duration. Future studies should aim to evaluate effects of artifact on postoperative imaging and, most notably, patient outcomes.
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3

SUGIOKA, Koji, Satoshi WADA, Hideo TASHIRO, and Koichi TOYODA. "Laser Ablation. Ablation Using Vacuum-Ultraviolet Lasers." Review of Laser Engineering 25, no. 4 (1997): 283–87. http://dx.doi.org/10.2184/lsj.25.283.

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4

Fan, Yujie, Kang Zhao, Mengjie Hao, Jing Xia, Xiaoyan Guan, and Fanghua Liu. "An Analysis of the Morphology Evolution of YG8 Cemented Carbide by Laser Ablation in the Liquid Phase." Coatings 13, no. 12 (December 9, 2023): 2061. http://dx.doi.org/10.3390/coatings13122061.

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To explore the influence of the number of laser ablations on the shape, geometry, and taper of the pitting structure by laser ablation in the liquid phase, three-dimensional confocal microscopy was used to quantitatively characterize the shape of the surface dotting texture of YG8 cemented carbide and analyze the evolution of the morphology based on the liquid-assisted laser ablation test. The results show that the surface pitting structure of YG8 cemented carbide evolves from a micro-convexity to a crater with the increase in the number of laser ablations, and the bottom of the crater produces a convexity after 7 ablations, the shape of the crater evolves to a trapezoidal shape after 13 ablations, and the shape is stable. The size of the dot texture increases with the number of laser ablations and reaches a maximum value of 396 μm in diameter and 149 μm in depth at the 10th and 12th ablations, respectively. The taper of the dot texture showed a trend of decreasing, increasing, and then decreasing with the increase in the number of laser ablations, and the taper was stable with more than seven ablations. This study lays a theoretical foundation for the control of the dot texture morphology on the surface of YG8 cemented carbide by laser ablation in a liquid-phase environment.
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5

SANZ, J., R. BETTI, and V. N. GONCHAROV. "Rayleigh–Taylor instability analysis of targets with a low-density ablation layer." Laser and Particle Beams 17, no. 2 (April 1999): 237–44. http://dx.doi.org/10.1017/s0263034699172094.

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Irregularities on the outer surface of Inertial Confinement Fusion (ICF) capsules accelerated by laser irradiation are amplified by the Rayleigh–Taylor instability (RTI), which occurs at the ablation front (ablative RTI), where density gradient and acceleration have the same direction. The analytic stability theory of subsonic ablation fronts, for Froude number larger than one, shows that the main stabilization mechanisms are blowoff convection (rocket effect equilibrating the gravity force) and ablation (Sanz 1994; Betti et al. 1996). Blowoff convection and ablation are enhanced if the ablator material is mixed with high-Z dopants. The latest enhances radiation emission setting the ablator on a higher adiabat, lowering its density, and increasing the ablation velocity. When such an ablator is used to push a solid deuterium-tritium (D–T) shell, the D–T-ablator interface becomes classically unstable. The aim of this paper is to investigate the stability of such a configuration, represented by a low-density ablator pushing a heavier shell, and study the interplay between the classical and ablative RTIs occurring simultaneously. The stability analysis is carried out using a sharp boundary model (Piriz et al. 1997), which contains all the basic physics of the RTI in ICF.
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6

Zajner, Chris, Jonathon Lau, Faical Isbaine, Nealen Laxpati, and Robert E. Gross. "1130 Anatomical Features Predicting Outcome From Stereotactic Laser Amygdalohippocampotomy." Neurosurgery 70, Supplement_1 (April 2024): 187. http://dx.doi.org/10.1227/neu.0000000000002809_1130.

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INTRODUCTION: Stereotactic laser amygdalohippocampotomy (SLAH) is a novel procedure which is effective and safe for the treatment of temporal lobe epilepsy. Optimal operative ablation location and extent, however, is uncertain, as are the neuroanatomical features guiding successful ablations. METHODS: Patients treated with SLAH for MTS at Emory University between 2011 and 2019 (n = 65) were considered in this retrospective study. Post-procedure T1 MRI scans of patients were used to create manual segmentations of the ablation region of each patient. Ablations were assessed in relation to 1) whether they crossed the coronal plane of the lateral mesencephalic sulcus (LMS), 2) the extent to which the ablation extended posterior to the LMS, and 3) extent of ablation of the uncus. Wilcoxon ranked-sign test was performed for each variable between groups of patients with Engel score 1 versus Engel score 2-4. RESULTS: Distance of ablation past the LMS was not different between Engel class 1 (mean 6.32 ± 4.16 mm), and Engel class 2-4 (7.93 ± 3.75 mm) (p = 0.099). Ratio of ablations extending posterior to the LMS was 0.82 (SD = 0.39) in Engel 1, and 0.90 (SD = 0.30) in Engel 2-4 (p = 0.370). Volume of ablation showed little correlation with outcome, with average ablation of Engel 1 = 6064 ± 2128 mm3, Engel 2-4 = 5828 ± 3031 mm3, and no significant difference with Wilcoxon ranked-sign test (p = 0.239). Ablation of the uncus showed a strong association with better surgical outcome, with ratio of uncus ablation for Engel 1 at 0.71(SD = 0.31), and Engel 2-4 at 0.37 (SD = 0.36); p < 0.001). CONCLUSIONS: Larger ablation alone was not associated with better surgical outcomes. Ablation of the uncus was shown to result in better outcomes. Contrary to current practice, extension of SLAH ablation posterior to the lateral mesencephalic sulcus did not demonstrate improved post-operative outcomes.
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Kansaku, Rei, Naoki Sakakibara, Atsushi Amano, Hisako Endo, Takashi Shimabukuro, and Michiaki Sueishi. "Histological difference between pulsed wave laser and continuous wave laser in endovenous laser ablation." Phlebology: The Journal of Venous Disease 30, no. 6 (May 30, 2014): 429–34. http://dx.doi.org/10.1177/0268355514538248.

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Background Endovenous laser ablation to saphenous veins has been popular as a minimally invasive treatment for chronic venous insufficiency. However, adverse effects after endovenous laser ablation using continuous wave laser still remain. Pulsed wave with enough short pulse duration and sufficiently long thermal relaxation time may avoid the excess energy delivery, which leads to the perforation of the vein wall. Method (1) Free radiation: Laser is radiated in blood for 10 s. (2) Endovenous laser ablation: Veins were filled with blood and placed in saline. Endovenous laser ablations were performed. Results (1) There were clots on the fiber tips with continuous wave laser while no clots with pulsed wave laser. (2) In 980-nm continuous wave, four of 15 specimens had ulcers and 11 of 15 had perforation. In 1470-nm continuous wave with 120 J/cm of linear endovenous energy density, two of three presented ulcers and one of three showed perforation. In 1470-nm continuous wave with 60 J/cm of linear endovenous energy density, two of four had ulcers and two of four had perforation. In 1320-nm pulsed wave, there were neither ulcers nor perforation in the specimens. Conclusions While endovenous laser ablation using continuous wave results in perforation in many cases, pulsed wave does not lead to perforation.
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John, Samuel, Yan Yan, Shirin Abbasi, and Mohammad Mehrmohammadi. "Ultrasound and Photoacoustic Imaging for the Guidance of Laser Ablation Procedures." Sensors 24, no. 11 (May 30, 2024): 3542. http://dx.doi.org/10.3390/s24113542.

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The accuracy and efficacy of laser ablation procedures depend on the accurate placement of the laser applicator within the diseased tissue, monitoring the real-time temperature during the ablation procedure, and mapping the extent of the ablated region. Ultrasound (US) imaging has been widely used to guide ablation procedures. While US imaging offers significant advantages for guiding ablation procedures, its limitations include low imaging contrast, angular dependency, and limited ability to monitor the temperature. Photoacoustic (PA) imaging is a relatively new imaging modality that inherits the advantages of US imaging and offers enhanced capabilities for laser-guided ablations, such as accurate, angle-independent tracking of ablation catheters, the potential for quantitative thermometry, and monitoring thermal lesion formation. This work provides an overview of ultrasound-guided procedures and how different US-related artifacts limit their utility, followed by introducing PA as complementary to US as a solution to address the existing limitations and improve ablation outcomes. Furthermore, we highlight the integration of PA-driven features into existing US-guided laser ablation systems, along with their limitations and future outlooks. Integrated US/PA-guided laser ablation procedures can lead to safer and more precise treatment outcomes.
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Liang, Allison, Sean Munier, and Shabbar Danish. "NIMG-68. MATHEMATICAL MODELING OF THERMAL DAMAGE ESTIMATE VOLUMES IN MAGNETIC RESONANCE-GUIDED LASER INTERSTITIAL THERMAL THERAPY." Neuro-Oncology 22, Supplement_2 (November 2020): ii163. http://dx.doi.org/10.1093/neuonc/noaa215.681.

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Abstract BACKGROUND Magnetic resonance-guided laser interstitial thermal therapy is a minimally invasive procedure that produces real-time thermal damage estimates of ablation (TDE). Orthogonal TDE-MRI slices provides an opportunity to mathematically estimate ablation volume. OBJECTIVE To mathematically model TDE volumes and validate with post-24 hours MRI ablation volumes. METHODS Ablations were performed with the Visualase Laser Ablation System (Medtronic). Using ellipsoidal parameters determined for dual-TDEs from orthogonal MRI planes, TDE volumes were calculated by two definite integral methods (A and B) implemented in Matlab (MathWorks). Post 24-hours MRI ablative volumes were measured in OsiriX (Pixmeo) by two-blinded raters and compared to TDE volumes via paired t-tests and Pearson’s correlations. RESULTS Twenty-two ablations for 20 patients with various intracranial pathologies were included. Average TDE volumes calculated with Method A was 3.44 ± 1.96 cm3 and with Method B was 4.83 ± 1.53 cm3. Method A TDE volumes were significantly different than post-24 hours volumes (P &lt; 0.001). Method B TDE volumes were not significantly different than post-24 hours volumes (P = 0.39) and strongly correlated with each other (r = 0.85, R2 = 0.72, P &lt; 0.0001). A total of 8/22 (36%) method A versus 17/22 (77%) method B TDE volumes were within 25% of the post 24-hours ablative volume. CONCLUSION We present the first iteration of a viable mathematical method that integrates dual-plane TDEs to calculate volumes resembling 24 hours post-operative volumes. Future iterations of our algorithm will need to determine additional calculated variables that improve the performance of volumetric calculations.
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10

Zajner, C., A. Taha, M. Abbass, F. Isbaine, N. Laxpati, R. Gross, and J. Lau. "P.079 Relationships between anatomical features and outcome after stereotactic laser amygdalohippocampotomy." Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques 51, s1 (May 24, 2024): S38. http://dx.doi.org/10.1017/cjn.2024.185.

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Background: Stereotactic laser amygdalohippocampotomy (SLAH) has recently been shown to be comparable to traditional temporal lobectomy procedures. The ideal extent and volume of laser ablations remains an area of investigation Methods: 65 patients treated with SLAH for MTS were considered in this retrospective study. Manual segmentations of ablations were created using post-procedure T1-MRI scans. Ablations were assessed in relation to whether they crossed the coronal plane of the superior lateral mesencephalic sulcus (LMS), the extent to which ablation crossed this landmark, and extent of ablation of the uncus. Analysis of was done with binary categorization of 12-month Engel classification score. Results: Distance of ablation posterior to the coronal plane of the LMS was not associated with better surgical outcome (Engel class 1: 6.32 ± 4.16 mm; Engel class 2-4: 7.93 ± 3.75mm; (p = 0.099)). Ratio of ablations extending posterior to the LMS was 0.82 (SD = .39) in Engel 1 patients, and 0.90 (SD = 0.3) in Engel 2-4 patients; (p = 0.370). Volume of ablation showed little correlation with outcome (Engel class 1: 6064 ± 2128 mm3; Engel class 2-4: 5828 ± 3031 mm3; (p=0.239)). Ablation of the uncus showed a strong association with better surgical outcome (Engel class 1: 0.71(SD = 0.31); Engel 2-4: 0.37 (SD = 0.36); p <0.001). Conclusions: Contrary to current practice, extension of ablation posterior to the LMS did not demonstrate improved outcome.
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11

Russo, Rchard E. "Laser Ablation." Applied Spectroscopy 49, no. 9 (September 1995): 14A—28A. http://dx.doi.org/10.1366/0003702953965399.

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12

Hwang, Lee, Gene Barnett, and Alireza Mohammadi. "SURG-07. STEREOTACTIC LASER ABLATION AS A THERAPEUTIC OPTION FOR RECURRENT GLIOBLASTOMA: A LARGE SINGLE INSTITUTIONAL EXPERIENCE." Neuro-Oncology 21, Supplement_6 (November 2019): vi241. http://dx.doi.org/10.1093/neuonc/noz175.1008.

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Abstract INTRODUCTION The prognosis of patients diagnosed with recurrent glioblastoma remains dismal, and therapeutic options are limited. The median survival is only 3 to 5 months. Stereotactic laser ablation is a minimally invasive neurosurgical technique used as an ablative treatment. We report outcomes of a large single institutional patient database of recurrent glioblastoma treated with laser ablation. METHODS Patients with recurrent glioblastoma, previously treated with biopsy or surgical resection plus standard radiation/temozolomide (and any other additional therapies), who underwent laser ablation with the NeuroBlate system at The Cleveland Clinic were retrospectively reviewed from 2011 through 2017. Primary endpoints were progression free survival (PFS) and overall survival (OS). RESULTS Between 2011 and 2017, 31 patients with recurrent glioblastoma were treated with laser ablation out of more than 250 laser ablation cases for brain tumors. This population included 17 males and 14 females. Age at the time of diagnosis ranged from 27 to 77. 84% underwent surgical resection as the initial treatment. 65% were treated with laser ablation after the first recurrence of previously treated glioblastoma. The average number of postoperative hospital days was 2.8, and most patients went home. 54% remained neurologically stable without new postoperative deficits, and 52% had no reported change in Karnofsky Performance Scale from before to after laser ablation. Median PFS was 5 months, and median OS was 13 months. CONCLUSIONS Laser ablation has been used to treat various intracranial lesions at The Cleveland Clinic, particularly recurrent glioblastoma. This treatment modality can be utilized at any point of recurrence in patients with appropriate clinical and radiographic characteristics. In addition, the minimally invasive nature and relatively short hospital stay in comparison to surgical tumor resection make laser ablation favorable. Laser ablation is becoming a valuable tool in a multidisciplinary approach to treat recurrent glioblastoma.
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Ross, Louis, Ahsan M. Naduvil, Juan C. Bulacio, Imad M. Najm, and Jorge A. Gonzalez-Martinez. "Stereoelectroencephalography-Guided Laser Ablations in Patients With Neocortical Pharmacoresistant Focal Epilepsy: Concept and Operative Technique." Operative Neurosurgery 15, no. 6 (March 14, 2018): 656–63. http://dx.doi.org/10.1093/ons/opy022.

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Abstract BACKGROUND Laser ablation surgery has had encouraging results in the treatment of multiple intracranial diseases including primary and metastatic brain tumors, radiation necrosis, and epilepsy. The use of the stereoelectroencephalography (SEEG) method in combination with laser thermocoagulation therapy with the goal of modulating epileptic networks in patients with neocortical nonlesional phamacoresistant epilepsy has not been previously described. OBJECTIVE To describe the novel methodological and conceptual aspects related to SEEG-guided laser ablations in patients with magnetic resonance imaging (MRI)-negative pharmacoresistant neocortical focal epilepsy. METHODS Guided by previous SEEG intracranial data, a laser ablation probe was inserted by using a robotic guidance device in a 17-yr-old medically refractory epilepsy patient with difficult to localize seizures and nonlesional MRI. The laser applicator position was confirmed by MRI, targeting the left mesial rostral superior frontal gyrus. The ablation was performed under multiplanar digital imaging views and real-time thermal imaging and treatment estimates in each plane. A postablation MRI (contrasted T1 sequence) confirmed the ablation's location and size. RESULTS The entire procedure was achieved in approximately 100 min. The actual ablation was performed in less than 3 min. Approximately, additional 30 min preoperatively were used for positioning and robot registration. Precise placement of laser application (in comparison with preplanned trajectories) was achieved using the robotic guidance and confirmed by the intraoperative magnetic resonance images. No complications were reported. The patient has been seizure-free since surgery. The follow-up period is 20 mo. Two additional patients, treated with similar methodology, are also described. CONCLUSION The preliminary experience with the described method shows the feasibility of a unique combination of the SEEG methodology with laser thermocoagulation in patients with neocortical MRI-negative pharmacoresistant focal epilepsy.
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Barnett, Gene H., Andrew E. Sloan, and Claudio E. Tatsui. "Introduction to Laser Ablation Video Supplement." Neurosurgical Focus 44, videosuppl2 (April 2018): Intro. http://dx.doi.org/10.3171/2018.4.focusvid.intro.

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Laser ablation (also known as laser interstitial thermal therapy [LITT]) has emerged as an important new technology for treating various disorders of the brain and spine. As with any new or emerging technology, there is a learning curve for its optimal use, and video tutorials can be important learning tools to help bridge gaps in knowledge for those who wish to become more familiar with laser ablation. In this special supplement to Neurosurgical Focus, videos illustrate laser ablation’s use in the treatment of epilepsy and failed radiosurgery, as well as technical aspects of performing these procedures in eloquent brain and in the spine. We hope that these videos will enable you to enhance your understanding of the evolving use of laser ablation for disorders of the brain or spine. It is the editors’ sincere hope that this will be helpful either in your own practice or in determining whether to refer to a neurosurgical colleague experienced in this field.
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Ahmed, Naveed, Saied Darwish, and Abdulrehman M. Alahmari. "Laser Ablation and Laser-Hybrid Ablation Processes: A Review." Materials and Manufacturing Processes 31, no. 9 (May 29, 2015): 1121–42. http://dx.doi.org/10.1080/10426914.2015.1048359.

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Chen, Bing, Ye Guo, Shunshun Li, and Guoyue Liu. "Experimental Study on Laser Ablation Texture-Assisted Grinding of Tungsten Alloy." Materials 15, no. 19 (October 10, 2022): 7028. http://dx.doi.org/10.3390/ma15197028.

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In order to machine the tungsten alloy with high efficiency, low damage and precision, laser ablation texture technology and precision grinding technology were combined to carry out grinding experiments of tungsten alloy and laser ablation texture-assisted grinding experiments. The advantages of laser ablation texture-assisted grinding tungsten alloy were investigated by comparing of the surface morphology, grinding force and surface roughness between ordinary grinding and laser ablative texture-assisted grinding. The results demonstrate that the surface morphology of ordinary grinding tungsten alloy was poor, the surface roughness was relatively high and the grinding force was relatively large. The surface morphology of the laser ablation texture-assisted grinding tungsten alloy processed by laser ablation texture was improved, the surface roughness decreased by 0.023 µm–0.204 µm, the normal force decreased by 49.91–59.46% and the tangent force decreased by 44.11–58.49%. Meantime, for the area ratio of texture A being the most, the grinding effect was related to the area ratio of texture, and the lowest grinding force and the best surface quality were observed on the tungsten alloy with the laser ablated texture A; the grinding forces and roughness of the other textures’ workpiece was similar and close because of their similar area ratios. The results demonstrate that laser ablation texture-assisted grinding of tungsten alloy could improve machining quality and reduce grinding force, which would provide guidance for realizing the high efficiency and precision machining of tungsten alloy.
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Junyu Mo, Junyu Mo, Yuqi Chen Yuqi Chen, Runhua Li Runhua Li, Qi Zhou Qi Zhou, and Yang Lou Yang Lou. "Microanalysis of silver jewellery by laser-ablation laser-induced breakdown spectroscopy with enhanced sensitivity and minimal sample ablation." Chinese Optics Letters 12, no. 8 (2014): 083001–83005. http://dx.doi.org/10.3788/col201412.083001.

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Sequeiros, Roberto Blanco, Juho Kariniemi, Risto Ojala, Li Chengli, Marianne Haapea, Andreas Blanco Sequeiros, and Osmo Tervonen. "Liver tumor laser ablation – increase in the subacute ablation lesion volume detected with post procedural MRI." Acta Radiologica 51, no. 5 (June 2010): 505–11. http://dx.doi.org/10.3109/02841851003694783.

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Background: The use of image-guided thermoablative methods in liver tumor treatment has expanded rapidly due to encouraging results and advanced imaging. However, little is known about the treatment-induced tissue response and effects on imaging findings during the subacute post procedural period. Purpose: To study the development of subacute ablation zone volume with magnetic resonance imaging (MRI) after laser-mediated liver tumor thermal therapy. Material and Methods: In all, 16 laser ablations were performed on 16 liver tumors resulting in 16 ablation zones in 11 consecutive patients. A low-field 0.23 T C-arm MRI scanner was used for imaging and procedural guidance. Repeated dynamic contrast-enhanced T1, contrast-enhanced T1 FSE, and T2 FSE studies of liver were performed at 0 and 72 h after the procedure. Ablation zone volumes were registered from the acquired image data. Results: MRI scans showed a significant increase of ablation volume in all imaging sequences obtained at 72 h after the initial therapy. Conclusion: After laser ablation, there is a progressive perfusion decrease in the ablation site leading to an increase in the ablation volume. Post procedural baseline MRI at 72 h from the treatment provides more precise information about the ablation result than can be obtained with immediate post procedural MRI.
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Jermakowicz, Walter J., Samir Sur, Iahn Cajigas, Pierre D’Haese, and Jonathan R. Jagid. "215 Laser Thermal Ablation for Mesiotemporal Epilepsy: Relation of Ablation Cavities to Seizure and Neurocognitive Outcomes." Neurosurgery 64, CN_suppl_1 (August 24, 2017): 258. http://dx.doi.org/10.1093/neuros/nyx417.215.

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Abstract INTRODUCTION Laser interstitial thermal therapy (LiTT) has dramatically changed the management of mesiotemporal epilepsy (mTLE) in recent years. The goal of this study was to identify features of ablations and trajectories that correlate with optimal seizure control and minimize the risk of neurocognitive deficits in patients undergoing LiTT for mTLE. METHODS Clinical and radiographic data were reviewed from a prospectively maintained database of patients undergoing LiTT for epilepsy at the University of Miami. Standard preoperative and postoperative evaluations, including contrast-enhanced MRI and neurocognitive testing, were performed in all patients. Laser trajectory and ablation volumes were computed both by manual tracing of mesiotemporal structures and by nonrigid registration of ablation cavities to a common reference system based on 7T MRI data. RESULTS >Of the 28 patients with at least 1-year follow-up, sparing of the mesial hippocampal head was significantly correlated with persistent disabling seizures (P = 0.01). Projecting all ablation cavities onto a common reference frame showed a clear tendency towards lateral placement of the laser with inadequate mesial hippocampal head ablation in these patients compared to those free of seizures. Patients that suffered deficits in memory, on the other hand, tended to have larger ablations with greater insult to entorrhinal and perirhinal cortex than those free of memory deficits. CONCLUSION Better understanding of the impact of ablation volume and location through the use of image normalization tools could potentially fine-tune this novel technique to improve seizure-freedom rates and associated neurocognitive deficits.
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Sierra-Trillo, Maria Isabel, Ralf Thomann, Ingo Krossing, Ralf Hanselmann, Rolf Mülhaupt, and Yi Thomann. "Laser Ablation on Isostatic Graphite—A New Way to Create Exfoliated Graphite." Materials 15, no. 16 (August 9, 2022): 5474. http://dx.doi.org/10.3390/ma15165474.

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In search of a new way to fabricate graphene-like materials, isostatic graphite targets were ablated using high peak power with a nanosecond-pulsed infrared laser. We conducted dry ablations in an argon atmosphere and liquid-phase ablations in the presence of a liquid medium (water or toluene). After the dry ablation, the SEM images of the target showed carbon in the form of a volcano-like grain structure, which seemed to be the result of liquid carbon ejected from the ablation center. No graphite exfoliation could be achieved using dry ablation. When using liquid phase ablation with water or toluene as a liquid medium, no traces of the formation of liquid carbon were found, but cleaner and deeper craters were observed. In particular, when using toluene as a liquid medium, typical graphite exfoliation was found. We believe that due to the extremely high pressure and high temperature induced by the laser pulses, toluene was able to intercalate into the graphite layers. Between the laser pulses, the intercalated toluene was able to flash evaporate and blow-up the graphite, which resulted in exfoliated graphite. Exfoliated graphite was found on the ablated graphite surface, as well as in the toluene medium. The ablation experiments with toluene undertaken in this study demonstrated an effective method of producing micrometer-sized graphene material. When using water as a liquid medium, no massive graphite exfoliation was observed. This meant that under the used laser conditions, toluene was a better intercalant for graphite exfoliation than water.
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Sasaki, Koichi, and Noriharu Takada. "Liquid-phase laser ablation." Pure and Applied Chemistry 82, no. 6 (May 2, 2010): 1317–27. http://dx.doi.org/10.1351/pac-con-09-10-23.

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The irradiation of an intense laser pulse onto a solid target immersed in liquid produces dense plasma. The plasma produced by liquid-phase laser ablation has unique features at high pressure and temperature, which are never realized by liquid-phase discharges. Another unique characteristic of liquid-phase laser ablation is the formation of a cavitation bubble. This article reports the fundamental aspects of liquid-phase laser-ablation plasmas, cavitation bubbles, and the formation processes of nanoparticles, together with some applications of liquid-phase laser ablation.
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Pacella, Claudio Maurizio, Giampiero Francica, and Giovanni Giuseppe Di Costanzo. "Laser Ablation for Small Hepatocellular Carcinoma." Radiology Research and Practice 2011 (2011): 1–8. http://dx.doi.org/10.1155/2011/595627.

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Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide and is increasingly detected at small size (<5 cm) owing to surveillance programmes in high-risk patients. For these cases, curative therapies such as resection, liver transplantation, or percutaneous ablation have been proposed. When surgical options are precluded, image-guided tumor ablation is recommended as the most appropriate therapeutic choice in terms of tumor local control, safety, and improvement in survival. Laser ablation (LA) represents one of currently available loco-ablative techniques: light is delivered via flexible quartz fibers of diameter from 300 to 600 μm inserted into tumor lesion through either fine needles (21g Chiba needles) or large-bore catheters. The thermal destruction of tissue is achieved through conversion of absorbed light (usually infrared) into heat. A range of different imaging modalities have been used to guide percutaneous laser ablation, but ultrasound and magnetic resonance imaging are most widely employed, according to local experience and resource availability. Available clinical data suggest that LA is highly effective in terms of tumoricidal capability with an excellent safety profile; the best results in terms of long-term survival are obtained in early HCC so that LA can be proposed not only in unresectable cases but, not differently from radiofrequency ablation, also as the first-line treatment.
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Duryea, Devyn, and Nirmala Kandadai. "Laser-induced galfenol embedded multi-layer graphene-oxide in solution." AIP Advances 12, no. 9 (September 1, 2022): 095011. http://dx.doi.org/10.1063/5.0106184.

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The proposed work demonstrates the direct synthesis of nanomaterial-embedded laser-induced few-layer graphene-oxide by directly ablating galfenol in a water-based solution for the first time. Laser-induced multilayer graphene-oxide (GO) embedded with galfenol (gallium–iron alloy) nanoparticles (NPs) is created through a method of direct laser inscription of bulk galfenol in deionized (DI) water with femtosecond laser ablation. The NP-embedded GO is achieved by irradiating a near-infrared (near-IR) femtosecond laser at 1040 nm on a bulk galfenol material submerged in a solution comprising DI water and a small concentration (5%/wt.) of polyvinylpyrrolidone followed by a second ablation in pure DI water. Results show nanoparticles with a mean diameter of ∼30 nm embedded in GO sheets with visible folds spaced at ∼0.63 nm. The composition of iron and gallium shifts by less than 2% during the laser ablation process, and the few-layer GO sheets exhibit similar Raman peaks to bulk graphite.
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MacDonell, Jacquelyn, Niravkumar Patel, Gregory Fischer, E. Clif Burdette, Jiang Qian, Vaibhav Chumbalkar, Goutam Ghoshal, et al. "Robotic Assisted MRI-Guided Interventional Interstitial MR-Guided Focused Ultrasound Ablation in a Swine Model." Neurosurgery 84, no. 5 (June 14, 2018): 1138–48. http://dx.doi.org/10.1093/neuros/nyy266.

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Abstract BACKGROUND Ablative lesions are current treatments for epilepsy and brain tumors. Interstitial magnetic resonance (MR) guided focused ultrasound (iMRgFUS) may be an alternate ablation technique which limits thermal tissue charring as compared to laser therapy (LITT) and can produce larger ablation patterns nearer the surface than transcranial MR guided focused ultrasound (tcMRgFUS). OBJECTIVE To describe our experience with interstitial focused ultrasound (iFUS) ablations in swine, using MR-guided robotically assisted (MRgRA) delivery. METHODS In an initial 3 animals, we optimized the workflow of the robot in the MR suite and made modifications to the robotic arm to allow range of motion. Then, 6 farm pigs (4 acute, 2 survival) underwent 7 iMRgFUS ablations using MRgRA. We altered dosing to explore differences between thermal dosing in brain as compared to other tissues. Imaging was compared to gross examination. RESULTS Our work culminated in adjustments to the MRgRA, iMRgFUS probes, and dosing, culminating in 2 survival surgeries; swine had ablations with no neurological sequelae at 2 wk postprocedure. Immediately following iMRgFUS therapy, diffusion-weighted imaging, and T1 weighted MR were accurate reflections of the ablation volume. T2 and fluid-attenuated inversion-recovery (FLAIR) images were accurate reflections of ablation volume 1-wk postprocedure. CONCLUSION We successfully performed MRgRA iFUS ablation in swine and found intraoperative and postoperative imaging to correlate with histological examination. These data are useful to validate our system and to guide imaging follow-up for thermal ablation lesions in brain tissue from our therapy, tcMRgFUS, and LITT.
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Gennaro, Nicolò, Giovanni Mauri, Gianluca Maria Varano, Lorenzo Monfardini, Vittorio Pedicini, Dario Poretti, and Luigi Alessandro Solbiati. "Thermal Ablations for Colorectal Liver Metastases." Digestive Disease Interventions 03, no. 02 (May 15, 2019): 117–25. http://dx.doi.org/10.1055/s-0039-1688724.

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AbstractApproximately 25% of colorectal cancers patients will develop hepatic metastases in the course of their disease. Surgical resection of hepatic metastases remains the first treatment choice for these patients, when feasible. However, only approximately 30% of metastatic lesions are resectable at the time of diagnosis. Thermal ablations have played an increasing role over the last few decades in the palliative and curative setting of colorectal liver metastases (CRLMs) in nonsurgical candidates with a liver-predominant disease. Several different techniques have been used to perform image-guided thermal ablations in the liver, including radiofrequency ablation, microwave ablation, cryoablation, and laser thermal ablation. We review the current ablation techniques, image-guidance modalities, indications, and debated topics of image-guided thermal ablation in CRLMs. Moreover, recent results from clinical trials are discussed along with future trends in liver thermal ablations.
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26

Mungmee, Amontep, and Sajee Sattayut. "An In Vitro Study of the Effect of CO2 Laser Power Output on Ablative Properties in Porcine Tongue." Life 13, no. 1 (January 5, 2023): 162. http://dx.doi.org/10.3390/life13010162.

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CO2 lasers have been generally used in oral soft-tissue surgery. Although an increase in power enhances the depth of ablation, the specific correlation between units of power and ablative depth has not been stated. This study aimed to explore ablative depth and width affected by a power unit of 10,600-nm CO2 laser continuous wave at 3 to 10 W in tissue blocks of the swine tongue. The 112 samples were randomly allocated into eight groups according to the power settings. The depth and width of the incision were measured by using the ImageJ program. The 3 W group showed the minimal depth of ablation [0.527 mm (0.474 and 0.817)] and width of ablation [0.147 mm (0.110 to 0.184)]. The maximal depth [3.750 mm (3.362 and 4.118)] and width [0.700 mm (0.541 to 0.860)] were in the 9 W group. The correlation between the ablative depth and power unit was 0.81 (p < 0.001). Based on the regression equation (p < 0.001), the ablative depth (mm) = (the power unit of laser in W x 0.491)-0.731. In conclusion, the ablative depth of the CO2 laser on soft tissue was strongly correlated to power units enabling the prediction equation.
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27

Welch, A. J., Massoud Motamedi, Sohi Rastegar, Gerald L. LeCarpentier, and Duco Jansen. "LASER THERMAL ABLATION." Photochemistry and Photobiology 53, no. 6 (June 1991): 815–23. http://dx.doi.org/10.1111/j.1751-1097.1991.tb09896.x.

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Ball, Kay A. "Laser Endometrial Ablation." AORN Journal 48, no. 6 (December 1988): 1153–64. http://dx.doi.org/10.1016/s0001-2092(07)69784-1.

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Khilnani, Neil M. "Endovenous Laser Ablation." Journal of Vascular and Interventional Radiology 16, no. 2 (February 2005): P148—P149. http://dx.doi.org/10.1016/s1051-0443(05)70134-2.

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Russo, Richard E., Xianglei Mao, and Oleg V. Borisov. "Laser ablation sampling." TrAC Trends in Analytical Chemistry 17, no. 8-9 (August 1998): 461–69. http://dx.doi.org/10.1016/s0165-9936(98)00047-8.

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Parrish, J. A. "Ultraviolet-laser ablation." Archives of Dermatology 121, no. 5 (May 1, 1985): 599–600. http://dx.doi.org/10.1001/archderm.121.5.599.

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Parrish, John A. "Ultraviolet-Laser Ablation." Archives of Dermatology 121, no. 5 (May 1, 1985): 599. http://dx.doi.org/10.1001/archderm.1985.01660050051012.

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Kochuev D. A., Chernikov A. S., Abramov D. V., Voznesenskaya A. A., Chkalov R. V., and Khorkov K. S. "Processes of ablation and structures growth under the action of femtosecond laser pulses on the gallium surface in an ammonia medium." Technical Physics 68, no. 4 (2023): 441. http://dx.doi.org/10.21883/tp.2023.04.55934.4-23.

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In this paper, we present the results of processing metallic gallium in an ammonia vapor medium at 2 bar pressure by femtosecond laser pulses. The influence of the ammonia concentration and the mode of laser beam scanning on the result of laser action is considered. It has been established that an increase in the concentration of ammonia vapor and a change in the scanning regime lead to a radical change in the laser ablation process. A decrease in the scanning speed leads to the cessation of the ablation process and the development of the nitridation process of the gallium surface, accompanied by the formation of columnar structures up to 12 mm long and about 100 μm in diameter. The synthesized nanoparticles and structures were studied using scanning electron microscopy, Raman spectroscopy, and X-ray analysis. Keywords: laser ablation, gallium nitride, gallium nitride nanoparticles manufacturing, ablative synthesis of gallium nitride nanoparticles.
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Semaltianos, Nikolaos G., Ona Balachninaitė, Remigijus Juškėnas, Audrius Drabavicius, Gediminas Niaura, and Euan Hendry. "Femtosecond Laser Ablation of a Bulk Graphite Target in Water for Polyyne and Nanomaterial Synthesis." Applied Sciences 13, no. 18 (September 17, 2023): 10388. http://dx.doi.org/10.3390/app131810388.

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Laser ablation of a bulk graphite target in water using femtosecond laser pulses (pulse width ≤ 190 fs) was performed to investigate the synthesis of polyynes and carbon-based nanomaterials and compare them with the well-studied cases of longer pulse (picosecond or nanosecond) ablations. The laser ablation products were characterized using UV-vis absorption spectroscopy, Raman spectroscopy, X-ray diffraction, and transmission electron microscopy, whereas the induced plasma plumes were characterized using laser-induced breakdown spectroscopy. Carbon-based nanomaterials and short-chain polyynes (C6H2 and C8H2) are formed in the solutions as proven by their characteristic absorption band at ~262 nm and peaks in the region of 190–240 nm as well as at around 2100 cm−1 in the Raman spectra, respectively. Polyynes (C8H2) are present in the solutions that are produced under an ablation that is carried out in two intervals with a short pause between them, which is contrary to a continuous ablation that is performed for the same total time duration. The ablation products have a hexagonal graphite crystal structure. The carbon-based nanomaterials consist of large non-spherical and small spherical nanoparticles as well as sheet-like structures. The results of the study were compared with previous studies and discussed based on those studies.
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35

Shin, Dong Ah. "Experimental Evaluation of Percutaneous Lumbar Laser Disc Decompression Using a 1414 nm Nd:YAG Laser." Pain Physician 6;18, no. 6;11 (November 14, 2015): E1091—E1099. http://dx.doi.org/10.36076/ppj.2015/18/e1091.

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Background: Laser ablation under an epiduroscopic view allows for the vaporization of a small amount of the nucleus pulposus, causing a reduction in intradiscal pressure and relief of radicular pain. Currently, Ho:YAG and Nd:YAG lasers are commonly used for spinal diseases. However, the use of the Nd:YAG laser for intra-spinal procedures can be limited because of thermal injury and low efficacy. Objective: To investigate the efficacy and safety of epiduroscopic laser ablation using a 1414 nm Nd:YAG laser, we examined that laser ablation was able to penetrate nucleus pulposus without heating surrounding tissues and without mechanical damage to surrounding tissue. Study Design: Our experiment involved live and cadaveric animal studies and a human cadaveric study. Setting: University in Korea. Methods: Two live pigs, 3 porcine cadavers, and 2 human cadavers were used. For the in vitro study, intradiscal and epidural pressure and temperature were compared in vertebral columns obtained from 3 porcine cadavers before and after laser ablation. For the in vivo study, 2 pigs were used to simulate percutaneous epiduroscopic laser ablation. They were observed for behavioral changes and neurological deficits for one month after the laser ablation procedure. Two human cadavers were used for placing the laser fiber and epiduroscope in the correct target site through the sacral hiatus. Histological analysis was also performed to observe any damage around the ablated lesion. Results: Both intradiscal and epidural pressure were markedly reduced immediately after laser ablation as compared with the pre-ablative state. The amount of the pressure decrease in the intradiscal space was significantly greater than that in the epidural space (45.8 ± 15.0 psi vs. 30.0 ± 9.6 psi, P = 0.000). The temperature beneath the ipsilateral spinal nerve, which was the nearest site to the laser probe, never exceeded 40º C. Histology revealed no evidence of thermal damage to surrounding structures, including the spinal nerves, end plates, and vertebrae, after laser ablation. All live pigs showed normal behavior without any sign of pain. In the human cadaveric study, there was no case of targeting failure or dural laceration. The mean time to reach the target region was less than 5 minutes. Limitations: The pressure measurements were performed on cadavers and not in vivo. Cadaver models cannot account for intradiscal pressure changes that occur during live muscle contraction and different positions, which may affect results. Moreover, although we controlled temperatures with heat baths, vascular and cerebrospinal fluid circulations were not simulated. Those circulations may change the temperature results in vivo. Conclusions: The 1414 nm Nd:YAG laser can be used effectively and safely under the guidance of a spinal epiduroscope in an in vivo porcine model and in a human cadaveric model. Study Approval: Approval for the current study was granted by the Institutional Review Board of our institute (approval number: 1-2014-0049). Key words: Intervertebral disc disease, laser-assisted spinal endoscopy, disc decompression, porcine spine, cadaver, animal model, intradiscal pressure, epidural pressure, Nd:YAG laser, laser ablation
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Hua, Yang, Zhenduo Zhang, Jiyu Du, Xiaoliang Liang, Wei Zhang, Yukui Cai, and Quanjing Wang. "Experimental and Simulation Research on Femtosecond Laser Induced Controllable Morphology of Monocrystalline SiC." Micromachines 15, no. 5 (April 26, 2024): 573. http://dx.doi.org/10.3390/mi15050573.

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Silicon carbide (SiC) is utilized in the automotive, semiconductor, and aerospace industries because of its desirable characteristics. Nevertheless, the traditional machining method induces surface microcracks, low geometrical precision, and severe tool wear due to the intrinsic high brittleness and hardness of SiC. Femtosecond laser processing as a high-precision machining method offers a new approach to SiC processing. However, during the process of femtosecond laser ablation, temperature redistribution and changes in geometrical morphology features are caused by alterations in carrier density. Therefore, the current study presented a multi-physics model that took carrier density alterations into account to more accurately predict the geometrical morphology for femtosecond laser ablating SiC. The transient nonlinear evolutions of the optical and physical characteristics of SiC irradiated by femtosecond laser were analyzed and the influence of laser parameters on the ablation morphology was studied. The femtosecond laser ablation experiments were performed, and the ablated surfaces were subsequently analyzed. The experimental results demonstrate that the proposed model can effectively predict the geometrical morphology. The predicted error of the ablation diameter is within the range from 0.15% to 7.44%. The predicted error of the ablation depth is within the range from 1.72% to 6.94%. This work can offer a new way to control the desired geometrical morphology of SiC in the automotive, semiconductor, and aerospace industries.
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Gornushkin, I. B., J. E. Kim, B. W. Smith, S. A. Baker, and J. D. Winefordner. "Determination of Cobalt in Soil, Steel, and Graphite Using Excited-State Laser Fluorescence Induced in a Laser Spark." Applied Spectroscopy 51, no. 7 (July 1997): 1055–59. http://dx.doi.org/10.1366/0003702971941485.

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An LIBS/LEAFS (laser-induced breakdown spectroscopy/laser-excited atomic Fluorescence spectrometry) combination with the use of simple open-air ultraviolet (UV) ablation has been investigated in terms of its analytical possibilities for the determination of cobalt in three solid sample matrices: graphite, soil, and steel. The fluorescence of cobalt was excited from a level which was already populated in the ablation plasma and was monitored at the Stokes-shifted wavelength. The optimal time delay between the ablating and exciting pulses was 16 μs. Detection limits in the ppb to ppm range and linearity over about four orders of magnitude were obtained. Excellent correlation of the LIBS/LEAFS with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and the certified value for Co in an SRM soil standard showed that both the precision and the accuracy of the LIBS/LEAFS method were satisfactory.
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38

SEMEROK, A., B. SALLÉ, J. F. WAGNER, and G. PETITE. "Femtosecond, picosecond, and nanosecond laser microablation: Laser plasma and crater investigation." Laser and Particle Beams 20, no. 1 (January 2002): 67–72. http://dx.doi.org/10.1017/s0263034602201093.

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Crater shapes and plasma plume expansion in the interaction of sharply focused laser beams (10 μm waist diameter, 60 fs–6 ns pulse duration) with metals in air at atmospheric pressure were studied. Laser ablation efficiencies and rates of plasma expansion were determined. The best ablation efficiency was observed with femtosecond laser pulses. It was found that for nanosecond pulses, the laser beam absorption, its scattering, and its reflection in plasma were the limiting factors for efficient laser ablation and precise material sampling with sharply focused laser beams. The experimental results obtained were analyzed with relation to different theoretical models of laser ablation.
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39

Flessenkämper, I., M. Hartmann, K. Hartmann, D. Stenger, and S. Roll. "Endovenous laser ablation with and without high ligation compared to high ligation and stripping for treatment of great saphenous varicose veins: Results of a multicentre randomised controlled trial with up to 6 years follow-up." Phlebology: The Journal of Venous Disease 31, no. 1 (October 22, 2014): 23–33. http://dx.doi.org/10.1177/0268355514555547.

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Objectives High ligation and stripping was compared to endovenous laser ablation for the therapy of great saphenous vein varicosity. Long-term efficacy was assessed in terms of avoidance of inguinal reflux and mechanisms of recurrence were investigated. Design Multicentre, randomised, three-arm, parallel trial. Materials and methods A total of 449 patients were randomised into three different treatment groups: high ligation and stripping group ( n = 159), endovenous laser ablation group ( n = 142; 980 nm, 30 W continuous mode, bare fibre) or a combination of laser ablation with high ligation (endovenous laser ablation group/ high ligation group, n = 148). Patients were examined clinically and by duplex ultrasound once a year. The primary end point of this study is inguinal reflux at the saphenofemoral junction after 2 years. This paper presents secondary data on sonographically determined inguinal reflux and clinical recurrences in the treated area after up to 6 years of follow-up. Results Median time to follow-up was 4.0 years; the mean time follow-up 3.6 years. Follow-up rates were: 2 years 74%, 3 years 47%, 4 years 39%, 5 years 36% and 6 years 31%. Most reflux into the great saphenous vein appeared in the endovenous laser ablation group (after 6 years: high ligation/stripping versus endovenous laser ablation p = 0.0102; high ligation/endovenous laser ablation vs. endovenous laser ablation p < 0.0002). Furthermore, more refluxive side branches were also observed in the endovenous laser ablation group (after 6 years high ligation/stripping vs. endovenous laser ablation p = 0.0569; high ligation/endovenous laser ablation vs. endovenous laser ablation p = 0.0111). In terms of clinical recurrence during the 6 years post therapy, no significant differences between the three treatment groups were observed ( p values from log-rank test: high ligation/stripping vs. endovenous laser ablation p = 0.5479; high ligation/stripping vs. high ligation/endovenous laser ablation p = 0.2324; high ligation/endovenous laser ablation vs. endovenous laser ablation p = 0.0848). The postoperative decline and later development in Class C (clinical etiological anatomical pathological) went parallel in all groups. Conclusions Clinical recurrence appears with the same frequency in all three treatment groups, but the responsible pathological mechanisms seem to differ. Most reflux into the great saphenous vein and side branches appears after endovenous laser ablation, whereas more saphenofemoral junction-independent recurrences are seen after high ligation/stripping.
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Attaar, Sakina J., Nitesh V. Patel, Eric Hargreaves, Irwin A. Keller, and Shabbar F. Danish. "Accuracy of Laser Placement With Frameless Stereotaxy in Magnetic Resonance-Guided Laser-Induced Thermal Therapy." Operative Neurosurgery 11, no. 4 (August 14, 2015): 554–63. http://dx.doi.org/10.1227/neu.0000000000000967.

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Abstract BACKGROUND As magnetic resonance-guided laser-induced thermal therapy (MRgLITT) becomes more accepted, there needs to be an evaluation of the techniques required to achieve accurate laser placement. OBJECTIVE To report our experience with frameless stereotaxy and the ability to achieve accurate laser placements. We also evaluate the variables associated with proper placement. METHODS We performed a retrospective analysis from 3 years of MRgLITT. Demographics and operational parameters, including trajectory length, target alignment error, registration error, and radial error were recorded and compared. Blinded review was used for completeness of ablation. RESULTS In the study, 90 laser placements were evaluated for 72 cases. Trajectory length and target alignment error was 95.3 ± 26.0 mm and 0.7 ± 0.3 mm, respectively. Significant differences existed in registration error between 4 (0.6 ± 0.3 mm) and 5 (0.5 ± 0.2 mm) skull pins (P = .04), but no significant decreases in registration error as additional skull pins were registered. Fifteen laser placements resulted in subtotal ablations. The overall radial error using frameless stereotaxy was 0.9 ± 1.6 mm. In the study, 65% of lasers were exactly on the planned trajectory. Of the 30 that were not, the radial error = 2.6 ± 1.9 mm. Radial error of subtotal laser ablations was 0.5 ± 0.9 (range, 0-2.8 mm) and was not significantly different from 0.8 ± 1.7 (range, 0-7.1 mm) radial error of lasers with total ablations (P = .52). Lasers with radial error &gt;0 mm resulted in an incomplete ablation in 26.7% of cases. CONCLUSION Skull pin-based frameless stereotaxy for MRgLITT results in consistent accuracy, with the majority of cases resulting in complete ablations. A significant proportion of lasers with RE &gt;0 mm still result in complete ablations.
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41

Dikovska, Anna Og, Daniela Karashanova, Genoveva Atanasova, Georgi Avdeev, Petar Atanasov, and Nikolay N. Nedyalkov. "Fabrication of Nanostructures Consisting of Composite Nanoparticles by Open-Air PLD." Coatings 14, no. 5 (April 24, 2024): 527. http://dx.doi.org/10.3390/coatings14050527.

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We present a two-step physical method for the fabrication of composite nanoparticle-based nanostructures. The proposed method is based on the pulsed laser deposition (PLD) technique performed sequentially in vacuum and in air. As a first step, thin-alloyed films of iron with noble metal were deposited by PLD in vacuum. The films were prepared by ablation of a mosaic target formed by equal iron and gold sectors. As a second step, the as-prepared alloyed films were ablated in air at atmospheric pressure as the laser beam scanned their surface. Two sets of experiments were performed in the second step, namely, by applying nanosecond (ns) and picosecond (ps) laser pulses for ablation. The structure, microstructure, morphology, and optical properties of the samples obtained were studied with respect to the laser ablation regime applied. The implementation of the ablation process in open air resulted in the formation of nanoparticle and/or nanoparticle aggregates in the plasma plume regardless of the ablation regime applied. These nanoparticles and/or nanoaggregates deposited on the substrate formed a complex porous structure. It was found that ablating FeAu films in air by ns pulses resulted in the fabrication of alloyed nanoparticles, while ablation by ps laser pulses results in separation of the metals in the alloy and further oxidation of Fe. In the latter case, the as-deposited structures also contain core–shell type nanoparticles, with the shell consisting of Fe-oxide phase. The obtained structures, regardless of the ablation regime applied, demonstrate a red-shifted plasmon resonance with respect to the plasmon resonance of pure Au nanoparticles.
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Xu, B., Y. Ma, X. Yang, W. Tang, S. Wang, Z. Ge, Y. Zhao, and Y. Ke. "Effect of high-Z dopant on the laser-driven ablative Richtmyer–Meshkov instability." Laser and Particle Beams 35, no. 2 (May 15, 2017): 366–72. http://dx.doi.org/10.1017/s0263034617000301.

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AbstractThe effects of high-Z dopant on the laser-driven ablative Richtmyer–Meshkov instability (RMI) are investigated by theoretical analysis and radiation hydrodynamics simulations. It is found that the oscillation amplitude of ablative RMI depends on the ablation velocity, the blow-off plasma velocity and the post-shock sound speed. Owing to enhancing the radiation at the plasma corona and increasing the radiation temperature at the ablation front, the high-Z dopant in plastic target can significantly increase the ablation velocity and the blow-off plasma velocity, leading to an increase in oscillation frequency and a reduction in oscillation amplitude of the ablative RMI. The high-Z dopant in plastic target is beneficial to reduce the seed of ablative Rayleigh–Taylor instability. These results are helpful for the design of direct drive inertial confinement fusion capsules.
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43

Xiong, Chang-Wei, Ching-Yen Ho, and Dong-Kai Qiao. "Analysis of Direct Optical Ablation and Sequent Thermal Ablation for the Ultrashort Pulsed Laser Photo-Thermal Micromachining." Coatings 10, no. 12 (November 25, 2020): 1151. http://dx.doi.org/10.3390/coatings10121151.

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An ultra-fast pulsed laser for materials processing can obtain submicrometer- to nanometer-sized parts or patterns (precision or accuracy) because the heat cannot diffuse in time for an ultra-fast pulsed duration, and this causes a threshold of ablation in multi-photoabsorption. The optical and thermal effects significantly affect the processing quality of an ultrashort pulsed laser for materials. This study utilizes a Laplace transform method to display the optical and thermal effects on the temperature field and the ablated depth of an ultrashort pulsed laser processing of materials. The results reveal that If an ultrafast pulsed laser-induced heat can keep the irradiated region above the evaporated temperature until the thermal diffusion occurs in the lattice of materials, thermal ablation occurs. The optical ablation can get a better processing quality due to less thermal diffusion. This study theoretically elucidates that the depth of optical ablation approximates the product of an optical absorption length and the logarithm of the ratio of laser fluence to laser fluence threshold. It has also been shown that the optical and thermal ablation, respectively, occur in low and high laser fluence because the optical ablation depends directly on the main source of the incident ultrashort pulsed laser. However, the thermal ablation is determined by the residual heat directly from the incident ultrashort pulsed laser after the optical ablation. The increase rate of the ablated depth per pulse with laser fluence is actually lower at high laser fluences than that at low laser fluences because the thermal ablation using the residual heat directly from the incident ultrashort pulsed laser is governed at high laser fluences. This study will provide the closed-form of a solution that elucidate the direct optical ablation and sequent thermal ablation for the ultra-fast pulsed laser photo-thermal processing.
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Sufian, S., S. Lakhanpal, and J. Marquez. "Superficial vein ablation for the treatment of primary chronic venous ulcers." Phlebology: The Journal of Venous Disease 26, no. 7 (June 24, 2011): 301–6. http://dx.doi.org/10.1258/phleb.2010.010058.

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Objective This retrospective study was undertaken to review our experience with ablation of superficial veins with significant reflux, using VNUS ClosureFAST RF (radiofrequency) or laser 980 nm, in patients with primary chronic venous ulcers, and also determine its effects in ulcer healing and ulcer recurrence. Method Included were 25 limbs (18 patients with chronic primary venous ulcers (clinical, aetiological, anatomical and pathological elements [CEAP] classification C6), who underwent endovenous ablation with RF for the axial veins or laser for the perforating veins during a two-year period. Results Of the 18 patients, there were eight men and 10 women. The median age of the group was 68 (range 37–89) years. The number of ablations done in each leg with an ulcer varied from one to eight, with a median of three. During a follow-up period of 6–12 months, one patient failed ulcer healing despite sequential ablations of refluxing veins. There was one case that developed recurrence of a small ulcer after six months and was successfully treated with a perforator ablation. Conclusion Endovenous ablation of incompetent superficial veins improves the healing of chronic primary venous ulcers and decreases the recurrence rates.
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TAKAHASHI, Tsutomu, Koji SUGIOKA, and Koichi TOYODA. "Laser Ablation. Fabrication of Micro-Magnetic Device by Excimer Laser Ablation." Review of Laser Engineering 25, no. 4 (1997): 301–5. http://dx.doi.org/10.2184/lsj.25.301.

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Masaharu Nishikino, Masaharu Nishikino, Noboru Hasegawa Noboru Hasegawa, Masahiko Ishino Masahiko Ishino, Yoshihiro Ochi Yoshihiro Ochi, Tetsuya Kawachi Tetsuya Kawachi, Mitsuru Yamagiwa Mitsuru Yamagiwa, and Yoshiaki Kato Yoshiaki Kato. "Soft X-ray laser observation of femtosecond-laser-driven ablation of tungsten." Chinese Optics Letters 13, no. 7 (2015): 070002–70004. http://dx.doi.org/10.3788/col201513.070002.

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Russo, R. E., X. L. Mao, C. Liu, and J. Gonzalez. "Laser assisted plasma spectrochemistry: laser ablation." Journal of Analytical Atomic Spectrometry 19, no. 9 (2004): 1084. http://dx.doi.org/10.1039/b403368j.

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Hein, Scott J., and Edward H. Piepmeier. "Laser ablation and the laser microprobe." TrAC Trends in Analytical Chemistry 7, no. 4 (April 1988): 137–42. http://dx.doi.org/10.1016/0165-9936(88)87011-0.

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Nakata, Y., T. Okada, and M. Maeda. "Lithographical laser ablation using femtosecond laser." Applied Physics A 79, no. 4-6 (September 2004): 1481–83. http://dx.doi.org/10.1007/s00339-004-2825-5.

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HIDAI, Hirofumi, Sho ITOH, and Hitoshi TOKURA. "3364 High-aspect-ratio Microdrilling with Laser Ablation." Proceedings of International Conference on Leading Edge Manufacturing in 21st century : LEM21 2011.6 (2011): _3364–1_—_3364–4_. http://dx.doi.org/10.1299/jsmelem.2011.6._3364-1_.

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