Abstract：
OBJECTIVE: The influence of the intracranial pressure field must be discussed with the development of a single-element transducer for low-intensity transcranial focused ultrasound because the skull plays a significant role in blocking and dispersing ultrasound wave propagation. Ultrasound propagation is mainly affected by the structure and acoustic properties of the skull; thus, we aimed to investigate the impact of simplifying the acoustic properties of the skull on the simulation of the transcranial pressure field to present guidance for efficient skull modeling in full-wave simulations.
METHODS: We constructed a three-dimensional computational model for ultrasound transmission with the same structure but varying acoustic properties of the skull. The structural information and heterogeneous acoustic properties of the skull were acquired from computed tomography images, and we segmented the skull into three layers (3 L), including spongy and compact bones. We then assigned homogeneous acoustic properties to a single layer (1 L) or 3 L of the skull. In addition, we investigated the influence of different types of transducers and different ultrasound frequencies (1.1 MHz, 0.5 MHz, and 0.25 MHz) on the intracranial pressure field to provide a comparison of the heterogenous and homogeneous models.
RESULTS: We indicated the importance of numerical simulations in estimating the intracranial pressure field of the skull owing to beam distortions. When we simplified the skull model, both the 1 L and 3 L models showed contours of the acoustic focus comparable to those of the heterogeneous model. When we evaluated the peak pressure and volume of the acoustic focus, the 1 L model produced a better estimation of peak pressure with a difference <10%, and the 3 L model is suitable to obtain smaller errors in the volume of the acoustic focus.
CONCLUSIONS: In conclusion, we examined the possibility of simplification of skull models using 1 L and 3 L homogeneous properties in the numerical simulation for focused ultrasound. The results show that the layered homogeneous model can provide characteristics comparable to those of the acoustic focus in heterogeneous models.
METHODS: We constructed a three-dimensional computational model for ultrasound transmission with the same structure but varying acoustic properties of the skull. The structural information and heterogeneous acoustic properties of the skull were acquired from computed tomography images, and we segmented the skull into three layers (3 L), including spongy and compact bones. We then assigned homogeneous acoustic properties to a single layer (1 L) or 3 L of the skull. In addition, we investigated the influence of different types of transducers and different ultrasound frequencies (1.1 MHz, 0.5 MHz, and 0.25 MHz) on the intracranial pressure field to provide a comparison of the heterogenous and homogeneous models.
RESULTS: We indicated the importance of numerical simulations in estimating the intracranial pressure field of the skull owing to beam distortions. When we simplified the skull model, both the 1 L and 3 L models showed contours of the acoustic focus comparable to those of the heterogeneous model. When we evaluated the peak pressure and volume of the acoustic focus, the 1 L model produced a better estimation of peak pressure with a difference <10%, and the 3 L model is suitable to obtain smaller errors in the volume of the acoustic focus.
CONCLUSIONS: In conclusion, we examined the possibility of simplification of skull models using 1 L and 3 L homogeneous properties in the numerical simulation for focused ultrasound. The results show that the layered homogeneous model can provide characteristics comparable to those of the acoustic focus in heterogeneous models.
摘要：
目的：必须通过开发用于低强度经颅聚焦超声的单元件换能器来讨论颅内压场的影响，因为颅骨在阻断和分散超声波传播中起着重要作用。超声传播主要受颅骨的结构和声学特性的影响；因此，我们旨在研究简化颅骨的声学特性对经颅压力场模拟的影响,为全波模拟中的有效颅骨建模提供指导.
方法：我们构建了用于超声传输的三维计算模型，该模型具有相同的结构，但颅骨的声学特性不同。从计算机断层扫描图像中获取颅骨的结构信息和非均匀声学特性，我们把头骨分成三层(3升),包括海绵状和紧凑的骨头。然后，我们将均匀的声学特性分配给颅骨的单层（1L）或3L。此外,我们研究了不同类型的换能器和不同超声频率(1.1MHz，0.5MHz,和0.25MHz）在颅内压场上提供异质和同质模型的比较。
结果：我们指出了数值模拟在估计由于光束畸变引起的颅骨颅内压场中的重要性。当我们简化头骨模型时，1L和3L模型均显示出与异质模型相当的声学焦点轮廓。当我们评估声焦点的峰值压力和体积时，1L模型产生了更好的峰值压力估计，差异<10%，3L模型适用于获得较小的声学焦点体积误差。
结论：结论：我们研究了在聚焦超声的数值模拟中使用1L和3L均质特性简化颅骨模型的可能性。结果表明，分层均匀模型可以提供与异质模型中声学焦点相当的特性。
方法：我们构建了用于超声传输的三维计算模型，该模型具有相同的结构，但颅骨的声学特性不同。从计算机断层扫描图像中获取颅骨的结构信息和非均匀声学特性，我们把头骨分成三层(3升),包括海绵状和紧凑的骨头。然后，我们将均匀的声学特性分配给颅骨的单层（1L）或3L。此外,我们研究了不同类型的换能器和不同超声频率(1.1MHz，0.5MHz,和0.25MHz）在颅内压场上提供异质和同质模型的比较。
结果：我们指出了数值模拟在估计由于光束畸变引起的颅骨颅内压场中的重要性。当我们简化头骨模型时，1L和3L模型均显示出与异质模型相当的声学焦点轮廓。当我们评估声焦点的峰值压力和体积时，1L模型产生了更好的峰值压力估计，差异<10%，3L模型适用于获得较小的声学焦点体积误差。
结论：结论：我们研究了在聚焦超声的数值模拟中使用1L和3L均质特性简化颅骨模型的可能性。结果表明，分层均匀模型可以提供与异质模型中声学焦点相当的特性。
