Spatial encoding using a code division technique for fast ultrasound imaging
Spatial encoding using a code division technique for fast ultrasound imaging
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DOI：
10.1109/tuffc.2008.613
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发表时间：
2008-02
期刊：
影响因子：
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通讯作者：
F. Gran;J. Jensen
中科院分区：
文献类型：
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作者：
F. Gran;J. Jensen
本文描述了一种合成发射孔径超声成像中的空间编码方法。这允许多个超声波源同时激活。该方法基于发送伪随机序列以对发送器进行空间编码。与其他空间编码技术（例如Hadamard 或Golay 编码）相反，可以仅在一次传输后使用所传输的代码序列的知识对数据进行解码。这使得该方法对运动不太敏感，并且可以使用更少的传输来获取数据。本文的目的是分析基础理论并测试物理系统的可行性。该方法已在使用 Field II 的模拟中进行了评估，其中针对 7 MHz 线性阵列换能器的不同深度模拟了点扩散函数。研究中还包括信噪比 (SNR) 模拟，与标准合成发射孔径 (STA) 发射方案相比，SNR 提高了约 1.5 dB。考虑到传输的能量量，该值较低。给出了合理的解释，并在模拟中得到验证。该方法还在实验超声扫描仪中进行了测试，并与使用正弦激励的合成发射孔径超声成像方案进行了比较。所提出的方法的性能在轴向和横向分辨率方面与参考方法相当，但与主瓣相比，其旁瓣水平在 ~ - 40 dB 处的对比度较差。
This paper describes a method for spatial encoding in synthetic transmit aperture ultrasound imaging. This allows several ultrasonic sources to be active simultaneously. The method is based on transmitting pseudorandom sequences to spatially encode the transmitters. The data can be decoded after only one transmission using the knowledge of the transmitted code sequences as opposed to other spatial encoding techniques, such as Hadamard or Golay encoding. This makes the method less sensitive to motion, and data can be acquired using fewer transmissions. The aim of this paper is to analyze the underlying theory and to test the feasibility in a physical system. The method has been evaluated in simulations using Field II in which the point-spread functions were simulated for different depths for a 7 MHz linear array transducer. A signal-to-noise ratio (SNR) simulation also was included in the study in which an improvement in SNR of ~1.5 dB was attained compared to the standard synthetic transmit aperture (STA) firing scheme. Considering the amount of energy transmitted, this value is low. A plausible explanation is given that is verified in simulation. The method also was tested in an experimental ultrasound scanner and compared to a synthetic transmit aperture ultrasound imaging scheme using a sinusoidal excitation. The performance of the proposed method was comparable to the reference with respect to axial and lateral resolution, but it displayed poorer contrast with sidelobe levels at ~ - 40 dB compared to the mainlobe.