Wound healing of 6.45-μm free electron laser skin incisions with heat-conducting templates

Robbins, Jason B.; Reinisch, Lou; Ellis, Darrel L.

doi:10.1117/1.1609452

Cited by 10 publications

(13 citation statements)

References 22 publications

(27 reference statements)

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“…There was no significant difference observed between the 1 and 200 ps micropulse duration at either 6.1 or 6.45 µm. The extent of thermal damage is consistent with that observed by previous authors at the same wavelength with the FEL, with 6.1 µm having significantly less damage than 6.45 µm [5,7]. There was no effect due to the micropulse duration on the type or extent of thermal damage on mouse dermis observed.…”

Section: Ablationsupporting

confidence: 94%

“…This difference, however, is small given the 200 fold reduction in the peak intensity, and is therefore negligible. Mouse dermis was selected as a tissue for comparing the resultant thermal damage between the two micropulse durations because it is easy to obtain and has been used by previous researchers as a marker for laser thermal damage with the FEL [5,7]. While mouse dermis is easy to obtain, the analysis of thermal damage is complicated due to the varying microstructure of the skin involving different cell types in the dermis, epidermis, and hair follicles, which leads to a great deal of variation [4].…”

Section: Ablationmentioning

confidence: 99%

“…Once embedded in paraffin, the skin was sectioned in 10 µm thick slices and mounted on slides. The slides were stained using Gomori's trichrome stain for light microscopic evaluation [5]. The zone of thermal damage was indicated by tincture changes in the trichrome-stained tissue.…”

Section: Histological Analysismentioning

confidence: 99%

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Analysis of soft tissue ablation using the pulse stretched free electron laser

et al. 2005

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The Mark-III Free Electron Laser (FEL), tuned to 6.45 microns in wavelength has been demonstrated to provide for efficient ablation in ocular, neural, and dermal tissues with minimal collateral damage. To date, the role of the unique pulse structure of the FEL on the ablation mechanism has not been determined. In this study, the native pulse structure of the FEL, a 2.85 gigahertz repetition of picosecond pulses within a five microsecond macropulse envelope, was changed using a pulse stretcher. This device changes the duration of the micropulse from its native one picosecond to 30-200 picoseconds in length, thus reducing the peak intensity of the micropulse down to 1/200 th of the original intensity, while the macropulse energy remains unchanged.Two basic metrics were studied: the ablation threshold on water and mouse dermis and the ablation crater depth on gelatin and mouse dermis. These metrics were employed at 6.45 and 6.1 microns in wavelength for 1, 100, and 200 picoseconds in micropulse duration. In addition, bright-field imaging was used to compare the ablation dynamic between 1 ps and 200 ps micropulses on water at 6.1 and 6.45 microns. The effect of changing the micropulse duration was also studied on the ablation of mouse dermis for histological analysis. Craters (500 micron diameter) were created with 25 pulses at three times the ablation threshold as determined for mouse dermis within 8 hours of removal. Three rows of twenty craters were created on each piece of mouse dermis for a given parameter set. The native one picosecond micropulse and 200 picosecond stretched micropulse were compared at 6.1 and 6.45 microns in wavelength. There was no difference seen between the native 1 ps micropulse and the stretched micropulse durations with respect to the ablation threshold, efficiency, dynamics, and thermal damage.

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Section: Ablationsupporting

confidence: 94%

Section: Ablationmentioning

confidence: 99%

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Analysis of soft tissue ablation using the pulse stretched free electron laser

et al. 2005

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“…Longer penetration depth will increase the number of damaged cells, while shorter penetration would result in less material removed per pulse. Whatever the underlying causes, biophysical investigations with a Mark-III free electron laser, tuned to 6.45 mm in wavelength have demonstrated minimal collateral damage and high ablation yield in ocular and neural tissues [13][14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Mid infrared optical parametric oscillator (OPO) as a viable alternative to tissue ablation with the free electron laser (FEL)

et al. 2007

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“…The Mark-III free electron laser (FEL), tuned to λ=6.45 µm has demonstrated the efficient ablation of soft tissue with minimal collateral damage [7][8][9][10][11][12]. While the Mark-III FEL has been used successfully in human neurosurgery and ophthalmic surgery based on these findings [7,9,10,[13][14][15][16] and has shown much promise for surgical applications, further advances are limited due to the expense and overhead related to the FEL.…”

Section: Introductionmentioning

confidence: 99%

Comparison of OPO and Mark-III FEL for mid-infrared soft tissue ablation

et al. 2005

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The goal of this study was to investigate a Q-switched Er:YAG pumped ZGP crystal Optical Parametric Oscillator (OPO) as a potential alternative source to the Mark-III Free Electron Laser (FEL) for delivering 6.45 micron light for clinical applications. In addition, this research increased the understanding of the role of the unique pulse structure of the FEL with respect to the ablation of soft tissue at 6.45 microns, which has been shown to ablate with very minimal collateral damage (<40 microns).The OPO operates from 6-8 microns in wavelength with a 100 ns pulse. Up to 250 micro-joules per pulse can be obtained with this laser. This provides up to three times the threshold energy for ablation given a diffraction limited spot of ~60 microns in diameter. The ablation threshold was determined using PROBIT analysis of 100 pulses on water at 6.1 and 6.45 microns in wavelength. The ablated crater depth was also measured on 90% w/w gelatin at both wavelengths for craters made with between 5 and 500 pulses.The results obtained with the OPO were then compared with a Mark-III FEL with a similar spotsize (~90 microns) to determine if there were any differences due to the unique pulse structure of the FEL, which consists of a 2.85 GHz train of picosecond pulses within a five microsecond envelope. The results showed no difference with respect to the ablation threshold; while the ablated crater depth was reduced for the FEL pulse for equivalent parameters. In addition, bright-field imaging was performed at three times the ablation threshold for both lasers and will be presented.

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Wound healing of 6.45-μm free electron laser skin incisions with heat-conducting templates

Cited by 10 publications

References 22 publications

Analysis of soft tissue ablation using the pulse stretched free electron laser

Analysis of soft tissue ablation using the pulse stretched free electron laser

Mid infrared optical parametric oscillator (OPO) as a viable alternative to tissue ablation with the free electron laser (FEL)

Comparison of OPO and Mark-III FEL for mid-infrared soft tissue ablation

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