Incident Fluence Analysis for 755‐nm Picosecond Laser Treatment of Pigmented Skin Lesions Based on Threshold Fluences for Melanosome Disruption

Shimojo, Yu; Nishimura, Takahiro; Hazama, Hisanao; Ito, Nobuhisa; Awazu, Kunio

doi:10.1002/lsm.23391

Cited by 14 publications

(20 citation statements)

References 46 publications

(69 reference statements)

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“…Lately, Yu et al investigated the threshold fluences for the melanosomes using the 755‐nm alexandrite picosecond laser and demonstrated that the threshold fluence at a pulse width of 750 ps is 2.49 J/cm 2 . The incident fluence may differ according to the depth of the melanosomes distributed in the skin tissue, and to destroy more deeply located melanosomes, larger spot sizes are preferred 8 . In light of these research results, parameters including a pulse width of 750 ps, a frequency of 1 Hz, a spot size of 3.2 mm, and an energy density of 2.49 J/cm 2 were used for this case.…”

Section: Discussionmentioning

confidence: 99%

“…The incident fluence may differ according to the depth of the melanosomes distributed in the skin tissue, and to destroy more deeply located melanosomes, larger spot sizes are preferred. 8 In light of these research results, parameters including a pulse width of 750 ps, a frequency of 1 Hz, a spot size of 3.2 mm, and an energy density of 2.49 J/cm 2 were used for this case. Seven days after the initial treatment, the local lesions had scabbed, and the scab fell off without scar formation.…”

Section: Discussionmentioning

confidence: 99%

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A case report on the use of 755‐nm alexandrite picosecond laser in the treatment of post‐inflammatory hyperpigmentation in the nose

Ren

Zhao

2021

J of Cosmetic Dermatology

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Post‐inflammatory hyperpigmentation (PIH), a common sequela of acute or chronic cutaneous inflammation, is an acquired pigmentary disorder. The main treatments for PIH, such as topical agents, photoprotection, and chemical peeling, demonstrated different efficacies with inconsistent outcomes. Here, we reported a case of nasal PIH treated using a 755‐nm alexandrite picosecond laser. The patient (female, aged 36 years) presented with a brown macula on the left side of the nasal dorsum 2 years ago, received treatment, and was followed up in the Plastic Surgery Department of Beijing hospital.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

A case report on the use of 755‐nm alexandrite picosecond laser in the treatment of post‐inflammatory hyperpigmentation in the nose

Ren

Zhao

2021

J of Cosmetic Dermatology

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“…52 Our previous study also indicated that a lower fluence of a picosecond laser pulse could produce treatment effects. 7 These studies suggest that immediate whitening may not be always necessary. Validation of the numerical results will lead to an improved selection of laser irradiation parameters for the treatment of epidermal pigmented lesions.…”

Section: Studymentioning

confidence: 99%

Nonlinear absorption‐based analysis of energy deposition in melanosomes for 532‐nm short‐pulsed laser skin treatment

et al. 2023

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Background and Objectives: The clinical use of 532-nm short-pulsed lasers has provided effective treatment of epidermal pigmented lesions. However, the detection of significant differences in treatment effects between picosecond and nanosecond lasers has still varied among clinical studies. For robust evaluation of the differences based on the treatment mechanism, this study presents a nonlinear absorption-based analysis of energy deposition in melanosomes for 532-nm shortpulsed laser treatment. Study Design/Materials and Methods: Nonlinear absorption by melanin is modeled based on sequential two-photon absorption. Absorption cross-sections and nonradiative lifetimes of melanin, which are necessary for the nonlinear absorption-based analysis, are determined from transmittance measurement. Using the model and parameters, energy deposition in melanosomes was calculated with varying fluence and pulse width settings, including actual clinical parameters.Results: The energy deposition in melanosomes increased with shorter laser pulses, and subnanosecond laser pulses were found to be most efficient. The comparison of energy deposition calculated using clinical parameters demonstrated the differences in treatment effects between picosecond and nanosecond lasers reported in clinical studies. Conclusion:The nonlinear absorption-based analysis provides quantitative evidence for the safety and efficacy evaluation of short-pulsed laser treatments, which may lead to the establishment of numerical indices for determining treatment conditions. Future studies considering the effects of the surrounding tissue on energy deposition in melanosomes will be needed.

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“…Compared with laparotomy and laparoscopic access, endoscopic access minimizes the number of incisions and sutures 7 . Furthermore, laser treatment is contactless, has high selectivity and high resolution, and has the possibility of automation based on robotic techniques 8 and numerical simulations 9 – 11 . Thus, endoscopic laser treatment offers minimally invasive treatment, short surgery time, and optimal precision 7 .…”

Section: Introductionmentioning

confidence: 99%

Endoscopic image-guided laser treatment system based on fiber bundle laser steering

Miyoshi

Nishimura

Shimojo

et al. 2023

Sci Rep

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A miniaturized endoscopic laser system with laser steering has great potential to expand the application of minimally invasive laser treatment for micro-lesions inside narrow organs. The conventional systems require separate optical paths for endoscopic imaging and laser steering, which limits their application inside narrower organs. Herein, we present a novel endoscopic image-guided laser treatment system with a thin tip that can access inside narrow organs. The system uses a single fiber bundle to simultaneously acquire endoscopic images and modulate the laser-irradiated area. The insertion and operation of the system in a narrow space were demonstrated using an artificial vascular model. Repeated laser steering along set targets demonstrated accurate laser irradiation within a root-mean-square error of 28 $$\mu$$ μ m, and static repeatability such that the laser irradiation position was controlled within a 12 $$\mu$$ μ m radius of dispersion about the mean trajectory. Unexpected irradiation on the distal irradiated plane due to fiber bundle crosstalk was reduced by selecting the appropriate laser input diameter. The laser steering trajectory spatially controlled the photothermal effects, vaporization, and coagulation of chicken liver tissue. This novel system achieves minimally invasive endoscopic laser treatment with high lesion-selectivity in narrow organs, such as the peripheral lung and coronary arteries.

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Incident Fluence Analysis for 755‐nm Picosecond Laser Treatment of Pigmented Skin Lesions Based on Threshold Fluences for Melanosome Disruption

Cited by 14 publications

References 46 publications

A case report on the use of 755‐nm alexandrite picosecond laser in the treatment of post‐inflammatory hyperpigmentation in the nose

A case report on the use of 755‐nm alexandrite picosecond laser in the treatment of post‐inflammatory hyperpigmentation in the nose

Nonlinear absorption‐based analysis of energy deposition in melanosomes for 532‐nm short‐pulsed laser skin treatment

Endoscopic image-guided laser treatment system based on fiber bundle laser steering

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