Retrieval of 3D information in X-ray dark-field imaging with a large field of view

X-ray dark-field imaging is a widely researched imaging technique, with many studies on samples of very different dimensions and at very different resolutions. However, retrieval of three-dimensional (3D) information for human thorax sized objects has not yet been demonstrated. We present a method, similar to classic tomography and tomosynthesis, to obtain 3D information in X-ray dark-field imaging. Here, the sample is moved through the divergent beam of a Talbot–Lau interferometer. Projections of features at different distances from the source seemingly move with different velocities over the detector, due to the cone beam geometry. The reconstruction of different focal planes exploits this effect. We imaged a chest phantom and were able to locate different features in the sample (e.g. the ribs, and two sample vials filled with water and air and placed in the phantom) to corresponding focal planes. Furthermore, we found that image quality and detectability of features is sufficient for image reconstruction with a dose of 68 μSv at an effective pixel size of $$0.357 \times {0.357}\,\mathrm{mm}^{2}$$ 0.357 × 0.357 mm 2 . Therefore, we successfully demonstrated that the presented method is able to retrieve 3D information in X-ray dark-field imaging.

Comparison of Geometrical Lung Models to Calculate Tidal Volumes during Spontaneous Breathing

Demographic changes, increasing air pollution and the ongoing Covid-19 pandemic, causing virus-induced respiratory failures, monitoring of respiratory parameters is the focus of international interest. In this study, motioncapture- system data was used to get circumferences of the human thorax while executing different breathing patterns. Four geometric models were used to model tidal volumes of the tracked person while using spirometry data as a reference. The results show that all four introduced models can be used for tidal volume calculation based on changes in the thoracic circumference. In terms of accuracy, the use-case must be considered

A Feasibility Study of 2-D Microwave Thorax Imaging Based on the Supervised Descent Method

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.

UWB Transmission through Human Thorax: An Index of Cardiac Health

There are many applications which require remote and non-invasive measurement of heartbeat of a human being using an ultra-wideband (UWB) radar. Sophisticated models and their analysis need to be referred before the design of a practical radar prototype. In this paper, i) a UWB wave propagation model of human thorax and ii) the power transmission coefficients estimated from the simulations of the model in the range 1-10 GHz using MATLAB are presented. The study reveals that there is a periodic variation of the transmission coefficients in correlation with the instantaneous physical dimensions of an active heart.

Testing the Validity of the NIJ Clay Standard for Approving Body Armor With a Preliminary Insight Into Injury Correlation

Body armor is tested for efficacy using the NIJ’s clay standard. This standard is based on a 44 mm upper limit of back face deformation into the clay to prevent severe cases of behind armor blunt trauma (BABT). The NIJ clay standard has never been directly correlated with human injury, and it is previously unknown how 44 mm into clay translates to the response of a human torso. This study developed a method for reproducing BABT in a laboratory setting, and performed matched pair testing on the ballistics clay and a cadaveric specimen. Tests at a low, non-injurious speed and a high, injurious speed were performed at the NIJ specified clay temperature, along with two tests at a lower temperature representing exposure to a room temperature setting. It was found that for both speeds the displacement into the human thorax was greater than the displacement into the clay. The greatest displacement into the clay was only 5mm above the standard’s limit, and the same speed into the human model caused failure of the ribcage. Lowering the clay temperature by two degrees Celsius resulted in a passing clay displacement for the extremely injurious high speed test. This experimentation is sufficient in showing that the NIJ standard may not be valid for preventing serious BABT injuries in the wearers of body armor. Further testing is required to correlate clay displacements with human injury risk.