טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentBeilin-Nissan Simona
SubjectStudy of Spatial and Frequency Compounding for Speckle
Reduction
DepartmentDepartment of Biomedical Engineering
Supervisor Professor Emeritus Dan Adam


Abstract

It is well known that a phenomenon termed ‘speckle’ which appears in incoherent ultrasound imaging systems, causes deterioration in quality of the ultrasound images. This issue has been the topic of many studies, which have produced a variety of approaches; the most popular approaches are compounding and filtering .


This work examines the issue of speckle reduction using a new array system. The new method of imaging utilizes three transducers for data acquisition.  The transducer placed at the center of the new transducer system is a phased array probe and acts as both transmitter and receiver. The other two transducers are unfocused pistons and act only as receivers. The suggested configuration allows acquisition of three images, and the individual images acquired by each transducer are combined to form a final improved image. Minimum correlation between individual images is necessary in order to maximize the advantages of compounding. Therefore, correlation is observed as a function of lateral translation between the transducers.


The advantages of this new array system and the combined compounding are:

  1. Expanding the bandwidth and utilizing the advantages of harmonic imaging - thus significantly improving the visibility and detectability of low contrast regions.
  1. Resolution is not deteriorated and even significantly improved.
  2. Compared to conventional compounding imaging, the new configuration does not cause a decrease in frame rate, as often happens, because only a single transducer is used in the transmit mode.

The technique which can be easily implemented, allows much better tissue classification in real time. The results of this study prove that the improvement in image quality is significant.