骨骼对于高强度聚焦超声聚焦影响的实验研究

目的:测定HIFU经过羊肩胛或人体离体颅骨形成的声压场及焦域，研究骨骼对HIFU聚焦的影响。方法:单阵元换能器发射超声波，经羊肩胛骨或者人体颅骨聚焦，通过水听器测量形成声场，通过含蛋清仿组织体模测量不同辐照条件形成的焦域大小。结果:羊肩胛骨及人体颅骨均可对声压造成极大的衰减；经骨骼后在激励功率达80 W时焦点声压与纯水中激励功率2 W相近，羊肩胛骨激励条件250 W、辐照时间3 min下可使仿体组织产生焦域；颅骨则在最大强度300 W、5 min下无焦域产生。结论:HIFU经骨骼聚焦时，增大输入功率或辐照时间，焦域体积增大。在单阵元换能器辐照环境下，经骨骼聚焦困难，焦点声压较低，形成焦域较小或无焦域形成，增大时间骨骼易产生热损伤。?

Research on the influence of bone on high intensity focused ultrasound focusing

Objective: To measure the sound pressure field and focal regions of HIFU to determine the effect of bone on ultrasound focusing. Methods: A single-element transducer was used for emitting ultrasound, the sound pressure was measured by hydrophone，and the focal regions were measured by egg-white tissue-mimicking phantom after sound wave spread through scapula of sheep or human skull. Results: Scapula of sheep and human skull both resulted in severe attenuation of sound pressure; similar sound pressure was observed in hydrophone when driving power was set to 2 W in degassed water and 80 W after scapula of sheep was added, and a focal region was generated in egg-white tissue-mimicking phantom with 250 W, 3 min; at maximum intensity 300 at 5 min， no focal region was observed when sound wave went through human skull. Conclusion: The focal regions increase with driving power or irradiation time. The sound pressure is low and focal regions are small or absent in the condition of the single-element. Increasing the irradiation time may cause thermal damage in bones.