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A new three-dimensional (3-D) acoustic image formation technique is proposed that is based on the transmission of wide bandwidth pulse signals and the application of the 3-D fast Fourier transform. A solution to the Helmholz wave equation has been obtained using the Born approximation. The solution contains analytical expressions for the spatial spectra of the transmit and receive radiation patterns for transducers of various geometries with lenses of fixed focal distances. It has been shown that the proposed algorithms allow for radiation patterns with constant widths at depths both behind and in front of the focal point, starting practically from the plane of the transducer. The theoretical and experimental investigations and computer simulation for both spherical and rectangular transducer shapes have been performed. The results were used to estimate the beamwidths and the side lobe levels. A variant of the linear array has been studied for cylindrical lens of a fixed focal distance moving in a lateral direction. It has been shown that, in this case, a high resolution (of the order of a few wavelengths) can be achieved along all three Cartesian coordinates at a very high scanning velocity. The influence of the moving scatterers' velocity in inhomogeneous medium on the spatial radiation pattern characteristics has been estimated.

BACKGROUND: The markup of medical image datasets is based on the subjective interpretation of the observed entities by radiologists. There is currently no widely accepted protocol for determining ground truth based on radiologists reports. AIM: To assess the accuracy of radiologist interpretations and their agreement for the publicly available dataset CTLungCa-500, as well as the relationship between these parameters and the number of independent readers of CT scans. MATERIALS AND METHODS: Thirty-four radiologists took part in the dataset markup. The dataset included 536 patients who were at high risk of developing lung cancer. For each scan, six radiologists worked independently to create a report. After that, an arbitrator reviewed the lesions discovered by them. The number of true-positive, false-positive, true-negative, and false-negative findings was calculated for each reader to assess diagnostic accuracy. Further, the inter-observer variability was analyzed using the percentage agreement metric. RESULTS: An increase in the number of independent readers providing CT scan interpretations leads to accuracy increase associated with a decrease in agreement. The majority of disagreements were associated with the presence of a lung nodule in a specific site of the CT scan. CONCLUSION: If arbitration is provided, an increase in the number of independent initial readers can improve their combined accuracy. The experience and diagnostic accuracy of individual readers have no bearing on the quality of a crowd-tagging annotation. At four independent readings per CT scan, the optimal balance of markup accuracy and cost was achieved.

Introduction. Medical imaging techniques can diagnose many diseases at the early stages of their development, improving the patient survival. Artificial intelligence (AI) systems, requiring the high-quality annotated and marked-up sets of medical images, are a suitable and promising means of improving the diagnostics’ quality. The purpose of the study was to develop a methodology and software for creating AIS training sets. Material and methods. We compared the main annotation methods’ performance and accuracy and based the information system on the most efficient method in both domains to develop an optimal approach. To markup objects of interest, we used the cluster model of lesions localization previously developed by the authors. We used C++ and Kotlin programming languages for software development. Results. A structured annotation template with delivered a glossary of terms became the basis of the information system. The latter consists of three interacting modules, two of which are executed on a remote server’s capacities and one on a personal computer or mobile device of the end-user. The first module is a web service responsible for the workflow logic. The second module, a web server, is responsible for interacting with client applications. Its role is to identify users and manage the database and Picture Archiving and Communication System (PACS) connections. The front-end module is a web application with a graphical interface that assists the end-user in images’ markup and annotation. Conclusions. An algorithmic basis and a software package have been created for annotation and markup of CT images. The resulting information system was used in a large-scale lung cancer screening project for the creation of medical imaging datasets.

The paper considers a 3D ultrasound imaging technique based upon usage of a probe that consists of 2 one-dimensional transmitting phased arrays and 3 receiving phased arrays. By controlling the transmit process on the elements of the transmitting array and simultaneous receiving the signals by all the elements of the receiving arrays, this method yields algorithmically synthesized signals of a 2D phased array, the so called virtual 2D phased array. This allows for achieving short volume scan time and high lateral and axial resolution. Lateral resolution is 2 times better than the Rayleigh limit of the original 1D phased arrays. The paper contains a mathematical simulation and experiment results.