Jang Doyoung, Yoon Heechul, Kim Gi-Duck, Hee Song Jae, Song Tai-Kyong
IEEE Trans Ultrason Ferroelectr Freq Control. 2024 Oct;71(10):1255-1268. doi: 10.1109/TUFFC.2024.3460688. Epub 2024 Oct 10.
A sparse array offers a significant reduction in the complexity of ultrasonic imaging systems by decreasing the number of active elements and associated electrical circuits needed to form a focused beam. Consequently, for 1-D arrays, it has been adopted in the development of miniaturized systems such as portable, handheld, or smartphone-based systems. Previously, we developed an analytic method that can design a pair of 1-D periodic sparse arrays (PSAs) satisfying three specific constraints, which are the array size, desired grating lobe level, and sparseness factor (SF). In this study, we further developed our method by incorporating aperture weighting functions, which take the form of tapered rectangular functions to introduce null points on the beam pattern. These null points effectively suppress grating lobes generated by a matching pair of arrays. The design process commences with determining transmit and receive PSA patterns, followed by deriving corresponding aperture weighting functions. First, aperture functions of a base and weighting arrays are convolved, which is then upsampled to the targeted array size. Finally, the upsampled aperture is convolved to an aperture function of a subarray, resulting in weighted PSAs (wPSAs). Pulsed wave (PW) simulation confirmed improved grating lobe suppression with wPSAs compared to PSAs. Phantom imaging experiments using a 1-D phased array validated the enhanced contrast due to suppressed grating lobes but at the cost of small degradation in lateral resolution. The signal-to-noise ratio (SNR) also gradually declined with the greater SFs, but no significant difference in SNR was observed between wPSAs and PSAs. Finally, in vivo echocardiography imaging highlighted the clinical potential of wPSAs, particularly with high SFs. Overall, these results suggest that wPSAs can effectively enhance contrast compared to PSAs under the given SF or, alternatively, wPSA with greater SFs can achieve comparable image quality to PSAs with lower SFs. In conclusion, the wPSA approach holds promise for further reducing the complexity of ultrasound imaging systems.
稀疏阵列通过减少形成聚焦波束所需的有源元件数量和相关电路，显著降低了超声成像系统的复杂性。因此，对于一维阵列，它已被应用于小型化系统的开发，如便携式、手持式或基于智能手机的系统。此前，我们开发了一种解析方法，该方法可以设计出满足三个特定约束条件的一对一维周期性稀疏阵列（PSA），这三个约束条件是阵列尺寸、所需的旁瓣电平以及稀疏因子（SF）。在本研究中，我们通过纳入孔径加权函数进一步改进了我们的方法，这些函数采用渐缩矩形函数的形式，以便在波束图上引入零点。这些零点有效地抑制了由一对匹配阵列产生的旁瓣。设计过程首先确定发射和接收PSA模式，然后推导相应的孔径加权函数。首先，对基础阵列和加权阵列的孔径函数进行卷积，然后将其向上采样到目标阵列尺寸。最后，将上采样后的孔径与子阵列的孔径函数进行卷积，得到加权PSA（wPSA）。脉冲波（PW）模拟证实，与PSA相比，wPSA的旁瓣抑制效果有所改善。使用一维相控阵的体模成像实验验证了由于旁瓣抑制而增强的对比度，但代价是横向分辨率略有下降。信噪比（SNR）也随着SF的增大而逐渐下降，但在wPSA和PSA之间未观察到SNR的显著差异。最后，体内超声心动图成像突出了wPSA的临床潜力，特别是在高SF情况下。总体而言，这些结果表明，在给定的SF下，与PSA相比，wPSA可以有效地增强对比度，或者，具有更大SF的wPSA可以实现与具有较低SF的PSA相当的图像质量。总之，wPSA方法有望进一步降低超声成像系统的复杂性。
