טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentErez Yael
SubjectSpatially Varying Frequency Compounding of Ultrasound Images
DepartmentDepartment of Electrical Engineering
Supervisors Professor Yoav Schechner
Professor Emeritus Dan Adam


Abstract

Ultrasound images are very noisy. Along with system noise, a significant noise source is the speckle phenomenon, caused mostly by interference. To treat the noise, we first study the statistical and physical characteristics of the signal and noise as a function of depth, acoustic frequency and probe properties. We show how these characteristics significantly change with depth, as well as with acoustic frequency. Based on these properties and the understanding of physical effects which degrade ultrasound images, we suggest methods for image improvement. Our approach is based on frequency compounding, in which images of the same object are acquired in different acoustic frequencies, and then compounded. Existing frequency compounding has been based on simple methods such as averaging, which have not achieved significant results. In contrast, our methods are based on the characteristics mentioned above. These methods treat the various noise sources, as well as signal attenuation while maintaining high resolution. We examine the proposed methods in experiments.