Thermo-Acoustic Imaging with the Current Injection

In the medical field, the electrical impedance tomography has the advantage of early diagnosis, in order to solve the problem of the low resolution the coupling imaging technologies with multi-physical fields are proposed. Thermo-acoustic imaging with the current injection (TAI-CI) is predicted theoretically and demonstrated using the phantom studies in this letter. By injecting current to phantom through a pair of electrodes, the joule heating is produced inside the objects and an acoustic signal is excited due to heat expansion. The electromagnetic field and acoustic field problems for TAI-CI basing electrical and thermal-acoustic coupling were solved in this paper, the equations and boundary conditions of target were derived under a quasi static electrical field approximation condition. The simulation and experiments were carried out aiming at low conductivity phantom (1 S/m and 5 S/m), an experimental set for TAI-CI was established to detect and collect the acoustic signals from the gel phantom, the conductivity variation of the gel phantom was reflected through image reconstruction, and B-scan image of the low conductivity (1 S/m) phantom with millimeter was produced.