Optical Coherence Tomography Guided Laser Cochleostomy: Towards the Accuracy on Tens of Micrometer Scale
Optical Coherence Tomography Guided Laser Cochleostomy: Towards the Accuracy on Tens of Micrometer Scale
复制标题
DOI：
10.1155/2014/251814
复制
发表时间：
2014-01-01
影响因子：
--
通讯作者：
Klenzner, Thomas
中科院分区：
文献类型：
--
作者：
Zhang, Yaokun;Pfeiffer, Tom;Klenzner, Thomas
激光已被证明是骨消融的精确工具。由于不会对患者施加机械应力，它们可能非常适合内耳等脆弱结构的显微手术。然而，在不损伤埋藏软组织的情况下控制激光-骨消融仍然具有挑战性。在这项工作中，我们演示了在光学相干层析成像(OCT)系统的监控下，对短脉冲CO2激光器进行闭环控制以执行激光耳蜗造口术。在暴露之前对骨-内骨-外淋巴边界进行几百微米的前瞻性探测已经实现。激光脉冲的位置和持续时间根据剩余骨厚度分布进行规划。OCT本身也被用作目标区域和光学系统之间的运动补偿的高精度跟踪系统。在新鲜猪耳蜗体外实验评估中，当残留组织层厚度均匀达到预定值时，消融过程自动终止。由此形成的沟底的形状会聚到骨内膜层的自然曲率，而不会损伤关键结构。OCT扫描的初步测量表明，形状近似的平均绝对精度仅为20微米左右。
Lasers have been proven to be precise tools for bone ablation. Applying no mechanical stress to the patient, they are potentially very suitable for microsurgery on fragile structures such as the inner ear. However, it remains challenging to control the laser-bone ablation without injuring embedded soft tissue. In this work, we demonstrate a closed-loop control of a short-pulsed CO2 laser to perform laser cochleostomy under the monitoring of an optical coherence tomography (OCT) system. A foresighted detection of the bone-endosteum-perilymph boundary several hundred micrometers before its exposure has been realized. Position and duration of the laser pulses are planned based on the residual bone thickness distribution. OCT itself is also used as a highly accurate tracking system for motion compensation between the target area and the optics. During ex vivo experimental evaluation on fresh porcine cochleae, the ablation process terminated automatically when the thickness of the residual tissue layer uniformly reached a predefined value. The shape of the resulting channel bottom converged to the natural curvature of the endosteal layer without injuring the critical structure. Preliminary measurements in OCT scans indicated that the mean absolute accuracy of the shape approximation was only around 20 mu m.