Coded excitation using periodic and unipolar M-sequences for photoacoustic imaging and flow measurement.
Coded excitation using periodic and unipolar M-sequences for photoacoustic imaging and flow measurement.
复制标题
DOI：
10.1364/oe.24.000017
复制
发表时间：
2016-01
期刊：
影响因子：
3.8
通讯作者：
Haichong K. Zhang;K. Kondo;M. Yamakawa;T. Shiina
中科院分区：
文献类型：
--
作者：
Haichong K. Zhang;K. Kondo;M. Yamakawa;T. Shiina
光声成像是一种新兴的成像技术，结合了光学成像和超声成像。与超声相比，光学吸收系数和流量测量的成像提供了额外的功能信息。光声成像的问题是由于散射或衰减导致的低信噪比（SNR）;当使用高脉冲重复频率（PRF）激光器时，这尤其成问题。在以前的研究中，编码激励利用几个伪随机序列已被认为是一个解决问题的方案。然而，先前提出的使用Golay码或M序列的时间编码过程是如此复杂，以至于需要发送两次序列来实现双极序列。在这里，我们提出了一个周期和单极序列（PUM），这是一个周期序列从一个m序列。PUM可以增强信号，而不会导致单波长激发的编码伪影。此外，由于解码开始点可以被设置为周期性照射中的任何代码，而只有序列的第一代码可用于传统的非周期性照射，因此可以增加时间分辨率。通过成像评估和流量测量实验验证了SNR的改善和时间分辨率的增加。
Photoacoustic imaging is an emerging imaging technology combining optical imaging with ultrasound. Imaging of the optical absorption coefficient and flow measurement provides additional functional information compared to ultrasound. The issue with photoacoustic imaging is its low signal-to-noise ratio (SNR) due to scattering or attenuation; this is especially problematic when high pulse repetition frequency (PRF) lasers are used. In previous research, coded excitation utilizing several pseudorandom sequences has been considered as a solution for the problem. However, previously proposed temporal coding procedures using Golay codes or M-sequences are so complex that it was necessary to send a sequence twice to realize a bipolar sequence. Here, we propose a periodic and unipolar sequence (PUM), which is a periodic sequence derived from an m-sequence. The PUM can enhance signals without causing coding artifacts for single wavelength excitation. In addition, it is possible to increase the temporal resolution since the decoding start point can be set to any code in periodic irradiation, while only the first code of a sequence was available for conventional aperiodic irradiation. The SNR improvement and the increase in temporal resolution were experimentally validated through imaging evaluation and flow measurement.