Simulated annealing based optimization of dual-ring arrays for forward-looking IVUS and ICE imaging

Forward-Looking (FL) catheter based imaging systems are highly desirable for guiding interventions in intravascular ultrasound (IVUS) and intracardiac echocardiography (ICE) applications. One of the main challenges in the array based FL-IVUS systems is the large channel count which results in increased system complexity. Synthetic phased array processing with reduced firing count simplifies the front-end and hence can enable 3-D real-time imaging. Recently, we have investigated dual-ring arrays suitable for IVUS and ICE imaging. In this study, we present two different optimized array designs based on dual circular and hexagonal rings that are suitable for synthetic phased array processing with reduced number of firings. To obtain optimal firing set that produces low side lobes in the wide-band response, we used simulated annealing algorithm. The simulated dual circular ring array has 64 Tx and 58 Rx elements, whereas the dual hexagonal ring array has 24 Tx and 126 Rx subarrays. For these two test cases, we obtained reduced sets of 512 and 256 coarray elements, and constructed 2-D PSFs at f/4 using 20-MHz, 50% FBW excitation. The simulation results show that the optimized dual circular and hexagonal ring arrays provide up to 10-dB and 5-dB improvements, respectively, in peak near side lobe level with no widening in main lobe width when compared with the full and uniformly sampled sparse coarrays.