Taudorf Elisabeth H, Haak Christina S, Erlendsson Andrés M, Philipsen Peter A, Anderson R Rox, Paasch Uwe, Haedersdal Merete
Department of Dermatology, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark.
Lasers Surg Med. 2014 Apr;46(4):281-9. doi: 10.1002/lsm.22228. Epub 2014 Feb 5.
Treatment of a variety of skin disorders with ablative fractional lasers (AFXL) is driving the development of portable AFXLs. This study measures micropore dimensions produced by a small 2,940 nm AFXL using a variety of stacked pulses, and determines a model correlating laser parameters with tissue effects.
Ex vivo pig skin was exposed to a miniaturized 2,940 nm AFXL, spot size 225 µm, density 5%, power levels 1.15-2.22 W, pulse durations 50-225 microseconds, pulse repetition rates 100-500 Hz, and 2, 20, or 50 stacked pulses, resulting in pulse energies of 2.3-12.8 mJ/microbeam and total energy levels of 4.6-640 mJ/microchannel. Histological endpoints were ablation depth (AD), coagulation zone (CZ) and ablation width (AW). Data were logarithmically transformed if required prior to linear regression analyses. Results for histological endpoints were combined in a mathematical model.
In 138 sections from 91 biopsies, AD ranged from 16 to a maximum of 1,348 µm and increased linearly with the logarithm of total energy delivered by stacked pulses, but also depended on variations in power, pulse duration, pulse repetition rate, and pulse energy (r(2) = 0.54-0.85, P < 0.0001). Microchannels deeper than 500 µm were created only by the highest pulse energy of 12.8 mJ/microbeam. Pulse stacking increased AD, and enlarged CZ and AW. CZ varied from 0 to 205 µm and increased linearly with total energy (r(2) = 0.56-0.75, P < 0.0001). AW ranged from 106 to 422 µm and increased linearly with the logarithm of number of stacked pulses (r(2) = 0.53-0.61, P < 0.001). The mathematical model estimated micropores of specific ADs with an associated range of CZs and AWs, for example, 300 µm ADs were associated with CZs from 27 to 73 µm and AWs from 190 to 347 µm.
Pulse stacking with a small, low power 2,940 nm AFXL created reproducible shallow to deep micropores, and influenced micropore configuration. Mathematical modeling established relations between laser settings and micropore dimensions, which assists in choosing laser settings for desired tissue effects.
用剥脱性分数激光（AFXL）治疗多种皮肤疾病推动了便携式AFXL的发展。本研究测量了一台小型2940nm AFXL使用多种堆叠脉冲产生的微孔尺寸，并确定了一个将激光参数与组织效应相关联的模型。
将离体猪皮暴露于一台小型化的2940nm AFXL下，光斑尺寸225μm，密度5%，功率水平1.15 - 2.22W，脉冲持续时间50 - 225微秒，脉冲重复频率100 - 500Hz，以及2、20或50个堆叠脉冲，产生的脉冲能量为2.3 - 12.8mJ/微束斑，总能量水平为4.6 - 640mJ/微通道。组织学终点为消融深度（AD）、凝固区（CZ）和消融宽度（AW）。在进行线性回归分析之前，如有需要对数据进行对数转换。将组织学终点的结果合并到一个数学模型中。
在来自91次活检的138个切片中，AD范围为16至最大1348μm，并随堆叠脉冲传递的总能量的对数呈线性增加，但也取决于功率、脉冲持续时间、脉冲重复频率和脉冲能量的变化（r² = 0.54 - 0.85，P < 0.0001）。仅通过12.8mJ/微束斑的最高脉冲能量产生了深度超过500μm的微通道。脉冲堆叠增加了AD，并扩大了CZ和AW。CZ范围为0至205μm，并随总能量呈线性增加（r² = 0.56 - 0.75，P < 0.0001）。AW范围为106至422μm，并随堆叠脉冲数的对数呈线性增加（r² = 0.53 - 0.61，P < 0.001）。该数学模型估计了具有相关CZ和AW范围的特定AD的微孔，例如，300μm的AD与27至73μm的CZ和190至347μm的AW相关。
使用小型、低功率的2940nm AFXL进行脉冲堆叠可产生可重复的浅至深微孔，并影响微孔形态。数学建模建立了激光设置与微孔尺寸之间的关系，这有助于为期望的组织效应选择激光设置。
