Wavelength-dependent threshold fluences for melanosome disruption to evaluate the treatment of pigmented lesions with 532-, 730-, 755-, 785-, and 1064-nm picosecond lasers

IF 2.2 3区医学 Q2 DERMATOLOGY Lasers in Surgery and Medicine Pub Date : 2024-03-04 DOI:10.1002/lsm.23773

Yu Shimojo PhD, Takahiro Nishimura PhD, Daisuke Tsuruta MD, PhD, Toshiyuki Ozawa MD, PhD, Henry Hin Lee Chan MD, PhD, FRCP, Taro Kono MD, PhD

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Abstract

Background and Objectives

A threshold fluence for melanosome disruption has the potential to provide a robust numerical indicator for establishing clinical endpoints for pigmented lesion treatment using a picosecond laser. Although the thresholds for a 755-nm picosecond laser were previously reported, the wavelength dependence has not been investigated. In this study, wavelength-dependent threshold fluences for melanosome disruption were determined. Using a mathematical model based on the thresholds, irradiation parameters for 532-, 730-, 755-, 785-, and 1064-nm picosecond laser treatments were evaluated quantitatively.

Study Design/Materials and Methods

A suspension of melanosomes extracted from porcine eyes was irradiated using picosecond lasers with varying fluence. The mean particle size of the irradiated melanosomes was measured by dynamic light scattering, and their disruption was observed by scanning electron microscopy to determine the disruption thresholds. A mathematical model was developed, combined with the threshold obtained and Monte Carlo light transport to calculate irradiation parameters required to disrupt melanosomes within the skin tissue.

Results

The threshold fluences were determined to be 0.95, 2.25, 2.75, and 6.50 J/cm² for 532-, 730-, 785-, and 1064-nm picosecond lasers, respectively. The numerical results quantitatively revealed the relationship between irradiation wavelength, incident fluence, and spot size required to disrupt melanosomes distributed at different depths in the skin tissue. The calculated irradiation parameters were consistent with clinical parameters that showed high efficacy with a low incidence of complications.

Conclusion

The wavelength-dependent thresholds for melanosome disruption were determined. The results of the evaluation of irradiation parameters from the threshold-based analysis provided numerical indicators for setting the clinical endpoints for 532-, 730-, 755-, 785-, and 1064-nm picosecond lasers.

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评估使用 532、730、755、785 和 1064 波长皮秒激光治疗色素性病变时黑色素体破坏的波长阈值流量。

背景和目的：黑色素体破坏的阈值流度有可能为使用皮秒激光治疗色素性病变提供一个可靠的数字指标，以确定临床终点。虽然以前曾报道过 755 纳米皮秒激光的阈值，但尚未研究其与波长的关系。本研究确定了黑色素体破坏的阈值流量与波长的关系。利用基于阈值的数学模型，对 532、730、755、785 和 1064 纳米皮秒激光治疗的辐照参数进行了定量评估：使用不同通量的皮秒激光照射从猪眼睛中提取的黑色素体悬浮液。用动态光散射法测量被照射黑色素体的平均粒径，并用扫描电子显微镜观察其破坏情况，以确定破坏阈值。结合获得的阈值和蒙特卡洛光传输建立了一个数学模型，以计算破坏皮肤组织内黑色素体所需的辐照参数：结果：532、730、785 和 1064 纳米皮秒激光的阈值流量分别为 0.95、2.25、2.75 和 6.50 J/cm²。数值结果定量揭示了破坏分布在皮肤组织不同深度的黑素体所需的辐照波长、入射通量和光斑大小之间的关系。计算出的辐照参数与临床参数一致，表明疗效高，并发症发生率低：结论：确定了黑素体破坏的波长阈值。基于阈值分析的辐照参数评估结果为设定 532、730、755、785 和 1064 纳米皮秒激光的临床终点提供了数字指标。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Lasers in Surgery and Medicine 医学-外科

CiteScore

5.40

自引率

12.50%

发文量

119

审稿时长

1 months

期刊介绍： Lasers in Surgery and Medicine publishes the highest quality research and clinical manuscripts in areas relating to the use of lasers in medicine and biology. The journal publishes basic and clinical studies on the therapeutic and diagnostic use of lasers in all the surgical and medical specialties. Contributions regarding clinical trials, new therapeutic techniques or instrumentation, laser biophysics and bioengineering, photobiology and photochemistry, outcomes research, cost-effectiveness, and other aspects of biomedicine are welcome. Using a process of rigorous yet rapid review of submitted manuscripts, findings of high scientific and medical interest are published with a minimum delay.