通过频率自适应调整聚焦参数，显著提升超声成像横向分辨率并消除伪影。
Frequency-Dependent F-Numbers Suppress Grating Lobes and Improve the Lateral Resolution in Line-by-Line Scanning
- 引入频变F数，动态优化发射与接收聚焦
- 横向分辨率最高提升24%，伪影完全消除
- 适合临床超声成像系统优化与高精度成像需求
线阵扫描是临床超声成像的标准方法，通过动态发射和接收孔径实现逐行聚焦。传统固定F数虽能扩展深度场并抑制栅瓣，但限制了横向分辨率。本文提出一种频率依赖的发射与接收F数设计，使低频时孔径更宽，从而提升分辨率。该方法可闭式表达，在保证深度场与栅瓣抑制的前提下最大化横向分辨率。体模实验表明，所提F数可完全消除栅瓣伪影，图像均匀性与对比度分别较全孔径提升14.1%与8.3%；相较于固定F数，横向分辨率最高提升24%。
原文摘要 · Abstract (English)
Line-by-line scanning with linear arrays is a standard image formation method in clinical ultrasound. This method examines progressively a given region of interest by conducting focused pulse-echo measurements with dynamic transmit and receive apertures. Such apertures widen with the focal length as a function of a given F-number and improve the image quality by extending the depth of field (DOF) and suppressing grating lobes. Fixed F-numbers, however, limit the lateral resolution. Herein, frequency dependence of the F-number is incorporated into both the transmit and the receive focusing to widen the apertures for low frequencies and improve the lateral resolution. Frequency-dependent transmit and receive F-numbers are proposed. These F-numbers, which can be expressed in closed form, maximize the lateral resolution under constraints on the DOF and the grating lobes. A phantom experiment showed that the proposed F-numbers eliminate grating lobe artifacts and improve both image uniformity and contrast to a similar extent as fixed F-numbers. These metrics, compared to the usage of the full apertures, improved by up to 14.1 % and 8.3 %, respectively. The proposed F-numbers, however, improved the lateral resolution by up to 24 % compared to the fixed F-numbers.
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