Electric signal diagnostics of plasma dynamics at an early stage of laser ablation

Abstract Background An institutional review board-approved, multicenter clinical trial was designed to determine the efficacy and outcome of percutaneous laser ablation (PLA) in the treatment of invasive ductal breast carcinoma (IDC). Post-ablation magnetic resonance imaging (MRI) was compared with surgical pathology in evaluation of residual post-ablation IDC and ductal carcinoma in situ. Methods Patients with a single focus of IDC 20 mm or smaller by pre-ablation MRI were treated with PLA. The patients underwent a 28-day post-ablation MRI, followed by surgical resection. Cell viability criteria were applied to pre- and post-ablation pathology specimens, which evaluated hematoxylin–eosin (H&E), cytokeratin (CK) 8/18, estrogen receptor, and Ki67 staining patterns. Results In this study, 61 patients were reported as the intention-to-treat cohort for determination of PLA efficacy. Of these 61 patients, 51 (84%) had complete tumor ablation confirmed by pathology analysis. One subject’s MRI imaging was not performed per protocol, which left 60 subjects evaluable for MRI pathology correlation. Five patients (8.3%) had residual IDC shown by both MRI and pathology. Post-ablation discordance was noted between MRI and pathology, with four patients (6.7%) false-positive and four patients (6.7%) false-negative. The negative predictive value (NPV) of MRI for all the patients was 92.2% (95% confidence interval [CI], 71.9–91.9%). Of the 47 patients (97.9%) with tumors 15 mm or smaller, 46 were completely ablated, with an MRI NPV of 97.7% (95% CI, 86.2–99.9%). Conclusions Percutaneous laser ablation is a potential alternative to surgery for treatment of early-stage IDC. Strong correlations exist between post-ablation MRI and pathologic alterations in CK8/18, ER, and Ki67 staining.

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Space- and time-resolved optical diagnosis for the study of laser ablation plasma dynamics

Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms ◽

10.1016/j.nimb.2008.10.057 ◽

2009 ◽

Vol 267 (2) ◽

pp. 446-450 ◽

Cited By ~ 28

Author(s):

C. Ursu ◽

S. Gurlui ◽

C. Focsa ◽

G. Popa

Keyword(s):

Laser Ablation ◽

Optical Diagnosis ◽

Plasma Dynamics ◽

Time Resolved ◽

Space And Time ◽

Ablation Plasma ◽

Laser Ablation Plasma

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Early-Stage Evolution of Electrons Emitted From Metal Target Surface During Ultrashort Laser Ablation in Vacuum

Volume 6: Fluids and Thermal Systems; Advances for Process Industries, Parts A and B ◽

10.1115/imece2011-63258 ◽

2011 ◽

Author(s):

Sha Tao ◽

Benxin Wu

Keyword(s):

Heat Transfer ◽

Laser Ablation ◽

Electric Field ◽

Early Stage ◽

Research Work ◽

Target Surface ◽

Electron Mass ◽

Metal Target ◽

Free Electron Density ◽

Ultrashort Laser

The early-stage evolution of electrons emitted from a metal target surface during ultrashort laser ablation in vacuum has been studied using a physics-based model. This kind of research work has been rarely reported in literature. In the model, the target heat transfer process is simulated by solving the two-temperature heat transfer equations, based on which the photoemission and thermionic emission of electrons from the target surface are calculated. The early-stage evolution of emitted electrons is described by solving the electron mass, momentum, and energy conservation equations, coupled with the Poisson’s equation that governs the developed electric field. The study shows that a relatively very high free electron density can be developed near the target surface, and the front of emitted electrons propagates very fast into the vacuum. The developed electric field strongly affects the evolution of emitted electrons. Using the physics-based model, the temporal variation and the spatial distribution of the emitted electron number density, and velocity will be studied and discussed. The early-stage evolution of the emitted electrons may affect the possible subsequent hydrodynamic motion in the target, and the resulted plasma formation and material removal (laser ablation) processes. Therefore, this study provides very useful information for the understanding of ultrashort laser-material interaction, laser-induced plasma, laser ablation (machining), and other relevant processes.

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Time-resolved EUV spectroscopy in the early stage of laser ablation of carbon

Applied Surface Science ◽

10.1016/s0169-4332(02)00319-7 ◽

2002 ◽

Vol 197-198 ◽

pp. 164-168 ◽

Cited By ~ 7

Author(s):

Pierre Loiseleur ◽

Tue N Hansen ◽

Jean Larour ◽

James G Lunney

Keyword(s):

Laser Ablation ◽

Early Stage ◽

Time Resolved

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Dynamics of picosecond laser ablation for surgical treatment of colorectal cancer

Scientific Reports ◽

10.1038/s41598-020-73349-w ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

R. J. Beck ◽

I. Bitharas ◽

D. P. Hand ◽

T. Maisey ◽

A. J. Moore ◽

...

Keyword(s):

Surgical Treatment ◽

Laser Ablation ◽

High Speed ◽

Thermal Damage ◽

Early Stage ◽

Colorectal Neoplasia ◽

Picosecond Laser ◽

Laser Pulses ◽

Surrounding Tissue ◽

Picosecond Laser Pulses

AbstractEndoluminal surgery for the treatment of colorectal neoplasia is typically carried out using electrocautery tools which imply limited precision and the risk of harm through collateral thermal damage to the adjacent healthy tissue. As a potential alternative, we present the successful colonic epithelial laser ablation by means of picosecond laser pulses. Laser ablation studies performed in ex-vivo colon tissue result in cavities with comparable thickness to early stage colorectal cancers. The corresponding histology sections exhibit only minimal collateral damage to the surrounding tissue and the depth of the ablation can be controlled precisely by means of the pulse energy. High-speed imaging has been used for the first time to visualize picosecond laser ablation of cancerous tissue in a clinically relevant model. This information was correlated with histopathology and optical surface profilometry revealing the dynamic nature of the laser tissue interaction and the need for temporal or spatial separation of pulses for optimum efficacy with regards to tissue removal. Overall, the application of picosecond laser pulses to ablate endoluminal bowel lesions demonstrates significantly improved precision and reduced thermal damage to the adjacent tissue in comparison to conventional procedures and hence will enable more precise surgical treatment of cancers.

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Sm1-xNdxNiO3 Thin Films Deposition by KrF Laser Ablation

Materials Science Forum ◽

10.4028/www.scientific.net/msf.609.27 ◽

2009 ◽

Vol 609 ◽

pp. 27-31

Author(s):

Slimane Lafane ◽

Tahar Kerdja ◽

Samira Abdelli-Messaci ◽

S. Malek ◽

M. Maaza

Keyword(s):

Rare Earth ◽

Transition Temperature ◽

Laser Ablation ◽

Perovskite Phase ◽

Thin Layers ◽

Silicon Substrates ◽

Plasma Dynamics ◽

Rutherford Back Scattering ◽

Thermal Range ◽

Krf Laser

The perovskites RNiO3 (R rare earth ≠ La) are classified as a phase transition metal-insulator. The transition temperature is modulated by the size of the rare earth. The use of compound R1-xR'xNiO3 can vary transition temperature on a wide thermal range depending on the concentration of the two rare earths. The Sm1-xNdxNiO3 (x = 0.45) thin layers have been carried out on (100) silicon substrates by KrF laser ablation (λ = 248 nm, 25ns) at two different fluences 2 and 3 Jcm-2. The oxygen pressure and the target-substrate distance have been maintained at 0.2 mbar and 4 cm respectively. The deposition temperature has been set at 500 ° C. The obtained layers were characterized by X-ray diffraction, atomic force microscopy and Rutherford back scattering diagnostics. The resistivity Measurements were carried out by the conventional four-probe method. The XRD spectra revealed the presence of an ideal cubic perovskite phase. The RBS analysis showed that the deposited layers are rich in oxygen. A correlation between the morphology properties of the deposited layers and the plasma dynamics studied by fast imaging has been found.

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