A preliminary system for microwave thorax imaging is designed and experiments are conducted. A compact low-profile symmetrical dipole antenna operating at 915 MHz is designed for the system. An acrylic rectangular box is fabricated as the experiment phantom to mimic an ordinary human thorax. Graduated cylinders with different diameters are used as imaging targets. During measurement, each antenna acts in turn as a transmitter and other antennas act as the receivers. One-step supervised descent method (SDM) is adopted as the imaging algorithm. Results under different scenarios indicate that structural information can be reconstructed with the one-step SDM. This study verifies the feasibility of microwave thorax imaging.

In this paper, the application of the supervised descent method (SDM) for 2-D microwave thorax imaging is studied. The forward modeling problem is solved by the finite element-boundary integral (FE-BI) method. According to the prior information of human thorax, a 3-ellipse training set is generated offline. Then, the average descent direction between an initial background model and the training models is calculated. Finally, the reconstruction of the testing thorax model is achieved based on the average descent directions online. The feasibility using One-Step SDM for thorax imaging is studied. Numerical results indicate that the structural information of thorax can be reconstructed. It has potential for real-time imaging in future clinical diagnosis.

The change of acoustic velocity in the human thorax reflects the functional status of the respiratory system. Imaging the thorax’s acoustic velocity distribution can be used to monitor the respiratory system. In this paper, the feasibility of imaging the human thorax using ultrasound traveltime tomography with a supervised descent method (SDM) is studied. The forward modeling is computed using the shortest path ray tracing (SPR) method. The training model is composed of homogeneous acoustic velocity background and a high-velocity rectangular block moving in the domain of interest (DoI). The average descent direction is learned from the training set. Numerical experiments are conducted to verify the method’s feasibility. Normal thorax model experiment proves that SDM traveltime tomography can efficiently reconstruct thorax acoustic velocity distribution. Numerical experiments based on synthetic thorax model of pleural effusion and pneumothorax show that SDM traveltime tomography has good generalization ability and can detect the change of acoustic velocity in human thorax. This method might be helpful for the diagnosis and evaluation of respiratory diseases.

A microwave thorax imaging system is designed for human respiration monitoring. A compact low-profile symmetrical dipole antenna is designed as sensing antenna. A 16-antenna array is fabricated and mounted on a wearable belt. The antenna array is controlled by a switch matrix and the data acquisition is completed with a vector network analyzer. During the measurement, each antenna acts as a transmitter alternately and the other antennas act as the receivers. Human respiration experiments are conducted and S-parameters are measured continuously during respiration. The Jacobian Weighted One-step Supervised Descent Method (SDM) is applied to the reconstruction of both synthetic and measured data. The distribution of dielectric properties in human thorax is reconstructed and the results verify the feasibility of monitoring human respiration with microwave.

In this work, we present a joint inversion framework that enables simultaneous reconstruction of electrical impedance tomography (EIT), microwave tomography (MWT), and ultra-sound tomography (UST). The structural and value features of the three modality images are decoupled and encoded into structure code and value code by the proposed disentangled variational autoencoder (DVAE). The inversion is then performed at the feature level, with the structure code and value code treated as unknown parameters to be inverted by the Gauss-Newton method. The interaction among the three modalities is achieved through structure code fusion, where the structure codes of the three modalities are averaged in the inversion as the fused structure code, thus ensuring the consistency of the structures in the three modalities. Two schemes are proposed to utilize the fused structure code. The initial code scheme (ICS) employs it as the initial structure code for the Gauss-Newton update of each modality. Meanwhile, the reference code scheme (RCS) designates it as the reference structure code. Numerical examples of human thorax imaging verify the effectiveness of the two schemes and demonstrate the advantages of the proposed joint inversion framework over separate inversions.