Spatial effect of conical angle on optical-thermal distribution for circumferential photocoagulation

Truong, Van Gia; Park, Suhyun; Tran, Vân Nam; Kang, Hyun Wook

doi:10.1364/boe.8.005663

Cited by 16 publications

(10 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, the instrument remains in a zone of a strong tissue heating. In case of bare silica fibers, unshaped or with complex tapered, rounded, or ball-like tips [54][55][56][57], it results in their possible damaging, which can even lead to surgical removal of fiber debris. Thus, along with the reduction of the delivered energy, overheating can be avoided by means of cooling or applying two or more fibers simultaneously [14,58], which complicates and enlarges the instrument.…”

Section: Discussionmentioning

confidence: 99%

Microfocusing sapphire capillary needle for laser surgery and therapy: Fabrication and characterization

Dolganova

Shikunova

Zotov

et al. 2020

Journal of Biophotonics

View full text Add to dashboard Cite

A sapphire shaped capillary needle designed for collimating and focusing of laser radiation was proposed and fabricated by the edge-defined film-fed growth technique. It features an as-grown surface quality, high transparency for visible and near-infrared radiation, high thermal and chemical resistance and the complex shape of the tip, which protects silica fibers. The needle's geometrical parameters can be adjusted for use in various situations, such as type of tissue, modality of therapy and treatment protocol. The focusing effect was demonstrated numerically and observed experimentally during coagulation of the ex vivo porcine liver samples. This needle in combination with 0.22NA optical fiber allows intensive and uniform coagulation of 150 mm 3 volume interstitially and 30 mm 3 superficially by laser exposure with 280 J without tissue carbonization and fiber damaging along with delicate treatment of small areas. The demonstrated results reveal the perspectives of the proposed sapphire microfocusing needle for laser surgery and therapy.

show abstract

Section: Discussionmentioning

confidence: 99%

Microfocusing sapphire capillary needle for laser surgery and therapy: Fabrication and characterization

Dolganova

Shikunova

Zotov

et al. 2020

Journal of Biophotonics

View full text Add to dashboard Cite

show abstract

“…This preliminary study investigates the feasibility of a cone‐shaped fiber probe that provides continuous‐wave IR laser radiation for SPLA in an ex vivo sheep esophageal model. A cone‐shaped fiber tip was obtained with the chemical etching technique previously examined for various fiber optic applications, including optical trapping and photocoagulation . In summary, we have designed, built, and tested a fiber probe that provides a tightly focused laser beam at close range for high‐efficiency photothermal ablation.…”

Section: Discussionmentioning

confidence: 99%

Superficial photothermal laser ablation of ex vivo sheep esophagus using a cone‐shaped optical fiber tip

Tozburun

2020

Journal of Biophotonics

View full text Add to dashboard Cite

Superficial photothermal laser ablation (SPLA) may be useful as a therapeutic approach producing a depth of injury that is sufficient to eliminate mucosal lesion but not deep enough to induce thermal effects in deeper tissue layers. The purpose of this preliminary study is twofold: (a) to describe design steps of a fiber probe capable of delivering a tightly focused laser beam, including Monte-Carlobased simulations, and (b) to complete the initial testing of the probe in a sheep esophagus model, ex vivo. The cone-shaped (tapered) fiber tip was obtained by chemical etching of the optical fiber. A 1505 nm diode laser providing power up to 500 mW was operated in continuous wave. The successful SPLA of the sheep mucosa layer was demonstrated for various speed-power combinations, including 300 mW laser power at a surface scanning rate of 0.5 mm/s and 450 mW laser power at a surface scanning rate of 2.0 mm/s. Upon further development, this probe may be useful for endoscopic photothermal laser ablation of the mucosa layer using relatively low laser power. K E Y W O R D S chemical etching, fiber probe, Monte Carlo, mucosa, photothermal ablation

show abstract

“…Particularly, the considered sapphire needles can be combined either with the conventional flat cleaved or diffusing optical fibers. 14,28,31,36,[38][39][40]58,59 The surface of diffusing fiber is partly matt at the end enabling both forward and lateral irradiation and ensuring a uniform irradiation of a large tissue volume. Additionally, a fiber can be moved along the channel inside a rigidly fixed needle during the tissue exposure.…”

Section: Discussionmentioning

confidence: 99%

Optimization of sapphire capillary needles for interstitial and percutaneous laser medicine

et al. 2019

View full text Add to dashboard Cite

Sapphire capillary needles fabricated by edge-defined film-fed growth (EFG) technique hold strong potential in laser thermotherapy and photodynamic therapy, thanks to the advanced physical properties of sapphire. These needles feature an as-grown optical quality, their length is tens of centimeters, and they contain internal capillary channels, with open or closed ends. They can serve as optically transparent bearing elements with optical fibers introduced into their capillary channels in order to deliver laser radiation to biological tissues for therapeutic and, in some cases, diagnostic purposes. A potential advantage of the EFG-grown sapphire needles is associated with an ability to form the tip of a needle with complex geometry, either as-grown or mechanically treated, aimed at controlling the output radiation pattern. In order to examine a potential of the radiation pattern shaping, we present a set of fabricated sapphire needles with different tips. We studied the radiation patterns formed at the output of these needles using a He-Ne laser as a light source, and used intralipid-based tissue phantoms to proof the concept experimentally and the Monte-Carlo modeling to proof it numerically. The observed results demonstrate a good agreement between the numerical and experimental data and reveal an ability to control within wide limits the direction of tissue exposure to light and the amount of exposed tissue by managing the sapphire needle tip geometry.

show abstract

Spatial effect of conical angle on optical-thermal distribution for circumferential photocoagulation

Cited by 16 publications

References 27 publications

Microfocusing sapphire capillary needle for laser surgery and therapy: Fabrication and characterization

Microfocusing sapphire capillary needle for laser surgery and therapy: Fabrication and characterization

Superficial photothermal laser ablation of ex vivo sheep esophagus using a cone‐shaped optical fiber tip

Optimization of sapphire capillary needles for interstitial and percutaneous laser medicine

Contact Info

Product

Resources

About