A Modified Synthetic Aperture Focusing Technique Utilizing Beam Characteristics of Transducer for Ultrasound Image Improvement

  • 何 嘉哲

Student thesis: Master's Thesis

Abstract

Synthetic aperture focusing technique (SAFT) has been proposed to improve the lateral resolution of ultrasound image outside the focal region of the transducer However SAFT would result an unexpected artifact image at the region near the focal point of transducer; which is due to the use of a virtue source concept associated with limited numbers of scan lines The artifact image could be eliminated by using an appropriate time gain compensation (TGC) However TGC is subjective to users’ settings To further improve this issue the present study incorporated the transducer’s depth-dependency beam characteristics into SAFT imaging procedure Ultrasound images were acquired using different frequency of single element transducers Initially the beam widths of transducer were estimated from B-mode wire images using from -3 to -20dB width Due to the erroneous time delay in accompanying with geometric calculation the time delay was also estimated from those B-mode wire images The -20dB beam width of transducer as a function of axial depth were measured for better estimating the time delay of each scanning point The modified SAFT were verified by means of self-made phantoms with wire targets and contrast targets and in-vivo images With the experiments the modified SAFT images with the correction of beam width of the transducer may not only retain the advantages of original SAFT but also improve the artifact image near the focal region The beam widths of transducer estimated from B-mode wire images using from -6 to -20dB width could be incorporated into SAFT imaging procedure and the modified SAFT was adaptive to different frequency of single element transducers These results show that current modified SAFT-based imaging may greatly enhance ultrasound image quality for further clinical applications
Date of Award2014 Sep 2
Original languageEnglish
SupervisorShyh-Hau Wang (Supervisor)

Cite this

A Modified Synthetic Aperture Focusing Technique Utilizing Beam Characteristics of Transducer for Ultrasound Image Improvement
嘉哲, 何. (Author). 2014 Sep 2

Student thesis: Master's Thesis