Geração de imagens por ultrassom utilizando as técnicas sparse arrays e plane wave

• Main Author: Schiefler Junior, Nivaldo Theodoro
• Publication Date: 2018
• Format: Doctoral thesis
• Language: por
• Source: Repositório Institucional da UTFPR (da Universidade Tecnológica Federal do Paraná (RIUT))
• Download full: http://repositorio.utfpr.edu.br/jspui/handle/1/3930
• topic: Ultrassom; Ultrassonografia; Diagnóstico por ultrassom; Processamento de imagens - Técnicas digitais; Transdutores; Ultrasonics; Ultrasonic imaging; Diagnostic ultrasonic imaging; Image processing - Digital techniques; Transducers; CNPQ::ENGENHARIAS::ENGENHARIA ELETRICA; Engenharia Elétrica

Nowadays, the major difficulties to improve the quality of the images using the ultrasonic techniques are related to the high number of shots used for transducer excitation, large quantities of storage data and the necessary computer processing for imaging. The purpose of this work is to evaluate the technique of image generation by ultrasound using the Stolt migration, based in plane wave and sparse arrays in the ultrasonic data reception. The plane wave technique was used to allow the increase of the frame rate by decreasing the number of shots of the ultrasound transducer elements. Simulations were made using a phantom developed in the Field II program in a Matlab environment and the actual data were acquired using the Verasonics Vantage 128 platform, with the 128-element L11-4v linear transducer. The simulated images were obtained by using a shooting sequence with angle variations for the 128 elements in the transmission and 128, 65, 44 and 23 elements for sparse arrays in the reception. The analysis of the results was accomplished by evaluating the axial and lateral resolutions using the FWHM criterion and the image quality with the criteria of contrast, MSE, SNR, PSNR and SSIM in the experimental and simulated images by using Stolt’s migration with plane wave and sparse arrays processing and the traditional DAS method. Qualitatively and quantitatively, the generated images by the proposed method showed similar results when compared in terms of the lateral and axial resolutions as well the quality image criteria. According to the results and the proposed processing method, the best sparse condition was obtained with 65 elements, indicating that the sparse reception suggested by the technique can be used for ultrasound image processing.