Ultrafast pulsed Bessel beams for enhanced laser ablation of bone tissue for applications in LASSOS
Ultrafast pulsed Bessel beams for enhanced laser ablation of bone tissue for applications in LASSOS
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超快脉冲贝塞尔光束，用于增强骨组织激光烧蚀，适用于 LASSOS
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发表时间：
2017
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通讯作者：
M. Simpson
中科院分区：
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作者：
Simon A. Ashforth;R. Oosterbeek;M. Simpson
采用飞秒脉冲激光系统（脉宽100 fs，重复频率500 Hz，波长800 nm），利用有效锥角为4.56°的LCOS空间光调制器（LCOS-SLM）产生了零级贝塞尔光束。使用最小损伤方法确定新鲜牛和绵羊承重皮质骨的消融阈值研究，发现在φth = 0.15 ± 0.03 J cm-2时相同，与靶种属无关。与牛和绵羊皮质骨中高斯光束确定的消融阈值相比，消融阈值显著降低（承重：φth = 0.91 ± 0.03 J cm-2，颅骨：φth = 1.19 ± 0.06 J cm-2）。对孵育效应进行了研究，孵育系数确定为Δ = 0.93 ± 0.06，表明不存在孵育效应。探讨了组织去除和施加脉冲的数量之间的关系。通过改变样品在入射激光的贝塞尔区域下的平移速率，改变施加在沿着线性烧蚀特征的每个点处的脉冲的数量。使用扫描电子显微镜（SEM）测量消融特征的横截面，并测量消融特征的最大深度。在注量为25.0 ~ 2.5Jcm ~（-2）范围内，牛和羊皮层的消融率分别为2.69 ~ 13.21 ± 0.05 μ mpulse ~（-1）和2.49 ~ 12.79 ± 0.03 μ mpulse ~（-1），明显高于高斯光束。使用SEM和光学显微镜对消融特征进行的结构分析显示，没有热影响区（HAZ）以热冲击波开裂、熔融碎屑沉积或组织炭化的形式出现的迹象。
Using a femtosecond pulsed laser system (pulse width = 100fs, repetition rate = 500 Hz, λ=800nm), a zero-order Bessel beam was generated using a LCOS-Spatial light modulator (LCOS-SLM) with an effective cone angle of 4.56°. Ablation threshold studies of fresh bovine and ovine load bearing cortical bone was identified using the method of least damage and found to be identical at φth = 0.15 ± 0.03 J cm-2, irrespective of the target species. The ablation threshold is significantly reduced compared to the ablation threshold determined for Gaussian beams in bovine and ovine cortical bone (Load Bearing: φth = 0.91 ± 0.03 J cm-2, Skull: φth = 1.19 ± 0.06 J cm-2). Incubation effects were investigated and the incubation coefficient was determined to be ζ = 0.93 ± 0.06, indicating no incubation effects are present. The relationship between tissue removal and the number of pulses applied was explored. By altering the translation rate of the sample under the Bessel region of the incident laser, the number of pulses applied at each point along the linear ablation features was varied. Cross sections of ablation features were measured using scanning electron microscopy (SEM) and maximum depths of the ablation features measured. The ablation rate of bovine and ovine cortical was found to be 2.69 – 13.21 ± 0.05 μm pulse-1 and 2.49 – 12.79 ± 0.03 μm pulse-1 respectively for fluence values ranging from 25.0 – 2.5 Jcm-2, significantly higher than those of Gaussian beams. Structural analysis of the ablation features using SEM and optical microscopy showed no signs of heat affected zone (HAZ) in the form of thermal shockwave cracking, molten debris deposition or charring of the tissue.