Technical Note: Compact thermoacoustic imaging system based on a low-cost and miniaturized microwave generator for in vivo biomedical imaging.

PURPOSE Most of existing thermoacoustic imaging (TAI) studies generally utilized a linear modulator-based high peak power magnetron generator (MG) for efficient TA signal excitation. However, a linear modulator-based MG is bulky and expensive. Here we present a low-cost and compact thermoacoustic imaging (TAI) system based on a miniaturized MG. METHODS The MG is based on solid state modulator and operates at 3.05±0.025 GHz, with a peak power of up to 60 kW and adjustable pulse duration from 70 to 600 ns. The dimensions and weight of this MG are 350×210×70 mm3 (Width × Length × Height) and 7.5 kg, respectively. RESULTS The spatial resolution of the miniaturized MG based TAI system is determined to be from 0.3 to 1.4 mm using controlled phantom experiments. The system is further evaluated using in vivo experiments where the finger joints and vasculature in the forearm and opisthenar of human participants are successfully imaged. CONCLUSIONS This study suggests that the miniaturized MG based TAI systems can be used for in vivo joint and vascular imaging with multiscale resolutions (0.3-1.4 mm).