Simulation of High Quality Ultrasound Imaging

This paper investigates if the influence on image quality using physical transducers can be simulated with an sufficient accuracy to reveal system performance. The influence is investigated in a comparative study between Synthetic Aperture Sequential Beamformation (SASB) and Dynamic Receive Focus (DRF). The study is performed as a series of simulations and validated by measurements. The influence from individual element impulse response, phase, and amplitude deviations are quantized by the lateral resolution (LR) at Full Width at Half Maximum (FWHM), Full Width at One-Tenth Maximum (FWOTM), and at Full Width at One-Hundredth Maximum (FWOHM) of 9 points spread functions resulting from evenly distributed point targets at depths ranging from 10 mm to 90 mm. The results are documented for a 64 channel system, using a 192 element linear array transducer model. A physical BK Medical 8804 transducer is modeled by incorporating measured element pulse echo responses into the simulation software. Validation is performed through measurements on a water phantom with three metal wires, each with a diameter of 0.07 mm. Results show that when comparing measurement and simulation, the lateral beam profile using SASB can be estimated with a correlation coefficient of 0.97. Further, it is shown that SASB successfully maintains a constant LR though depth at FWHM, and is a factor of 2.3 better than DRF at 80 mm. However, when using SASB the LR at FWOHM is affected by non-ideal element responses. Introducing amplitude and phase compensation, the LR at FWOHM improves from 6.3 mm to 4.7 mm and is a factor of 2.2 better than DRF. This study has shown that individual element impulse response, phase, and amplitude deviations are important to include in simulated system performance evaluations. Furthermore, it is shown that SASB provides a constant LR through depth and has improved resolution and contrast compared to DRF.