Heat diffusion and debris screening in Er:YAG laser ablation of hard biological tissues

Majaron, Boris; Sustercic, Dusan; Lukač, Matjaž; Skalerić, U; Funduk, Nenad

doi:10.1007/s003400050423

Cited by 81 publications

(79 citation statements)

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“…Such a trend was predicted from theoretical considerations of thermo-mechanical laser ablation [36±38], and results from increased ablation ef®ciency at higher¯uences which diminishes the residual thermal damage. With repetitive irradiation, the heat deposition at lower pulse¯uences is likely enhanced due to skin desiccation between subsequent laser pulses, which removes the main absorber of the Er:YAG laser radiation [38,39]. Consequently, the optical penetration depth increases, resulting in further diminished ablation ef®-ciency, enhanced deposition of heat, and increased thermal injury.…”

Section: Discussionmentioning

confidence: 99%

Er:YAG laser skin resurfacing using repetitive long‐pulse exposure and cryogen spray cooling: I. Histological study*

et al. 2001

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Background and Objective: To evaluate histologically the characteristics of repetitive Er:YAG laser exposure of skin in combination with cryogen spray cooling (CSC), and its potential as a method of laser skin resurfacing. Study Design/Materials and Methods: Rat skin was irradiated in vivo with sequences of 10 Er:YAG laser pulses (repetition rate 20 Hz, pulse duration 150 or 550 ms, single-pulse¯uence 1.3±5.2 J/cm 2 ). In some examples, CSC was applied to reduce epidermal injury. Histologic evaluation was performed 1 hour, 1 day, 5 days, and 4 weeks post-irradiation. Results: A sequence of ten 550-ms pulses with¯uences around 2 J/cm 2 resulted in acute dermal collagen coagulation to a depth of approximately 250 mm, without complete epidermal ablation. CSC improved epidermal preservation, but also diminished the coagulation depth. Four weeks after irradiation, neo-collagen formation was observed to depths in excess of 100 mm. Conclusion: Dermal collagen coagulation and neo-collagen formation to depths similar to those observed after CO 2 laser resurfacing can be achieved without complete ablation of the epidermis by rapidly stacking long Er:YAG laser pulses. Application of CSC does not offer signi®cant epidermal protection for a given dermal coagulation depth.

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Section: Discussionmentioning

confidence: 99%

Er:YAG laser skin resurfacing using repetitive long‐pulse exposure and cryogen spray cooling: I. Histological study*

et al. 2001

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“…As the beam travels beyond the focal plane of the focusing Since the multiple Er:YAG pulse produces deep craters, it is expected that the ablation efficiency drops as a result of decreased radiant exposure. The debris shielding is another phenomenon that can explain the reduced efficiency of Er:YAG laser beam [29][30][31]. Once the debris is generated during the laser-tissue interaction, the remaining part of the laser pulse will be partially absorbed and scattered by the debris (termed ''debris shielding''), reducing the pulse energy that reaches the target and diminishing the ablation efficiency.…”

Section: Ablation Volumementioning

confidence: 99%

Urinary calculus fragmentation during Ho: YAG and Er:YAG lithotripsy

et al. 2005

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Background and Objectives: We tested Ho:YAG and Er:YAG laser ablation of human urinary calculi to determine if Er:YAG is a more efficient lithotripsy device. Study Design/Materials and Methods: Ablation efficiency of Ho:YAG and Er:YAG lasers was tested at varying energy settings, ranging from the damage threshold to clinical energy setting associated with Ho:YAG laser. Stones of known composition (calcium oxalate monohydrate (COM), cystine, and uric acid (UA)) were irradiated. Crater width, depth, and ablation volumes were determined using an optical coherence tomography (OCT). Results: For all stones and energy settings, the Er:YAG laser produced deeper craters and larger ablation volumes than Ho:YAG laser. The Ho:YAG laser created wider craters during the multiple pulse process and the shape of craters was irregular. Conclusions: The Er:YAG laser is more efficient than the Ho:YAG laser for lithotripsy. The deeper craters produced by the Er:YAG laser is attributed to the high absorption of energy at its wavelength.

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“…In addition, the laser radiation should not be absorbed or scattered by the ablation debris, which is called debris screening [2][3][4]. This is discussed in more detail at the end of the article, after an analysis of some specifics of ablation with repetitively pulsed laser irradiation.…”

Section: Introductionmentioning

confidence: 97%