title: Improving beamforming performance by phased synthetic aperture imaging in medical ultrasound.
abstract: OBJECTIVE
  Ultrasound image quality is related to the receive beamformer's ability. Delay and sum (DAS), a conventional beamformer, is combined with the coherence factor (CF) technique to suppress side lobe levels. The purpose of this study is to improve these beamformer's abilities.
  
  
  METHODS
  It has been shown that extension of the receive aperture can improve the receive beamformer's ability in radar studies. This paper shows that the focusing quality of CF and CF+DAS in medical ultrasound can be increased by extension of the receive aperture's length in phased synthetic aperture (PSA) imaging.
  
  
  RESULTS
  The 3-dB width of the main lobe in the receive beam related to CF focusing decreased to 0.55 mm using the proposed PSA compared to the conventional phased array (PHA) imaging, whose FWHM is about 0.9 mm. The clutter-to-total-energy ratio (CTR) represented by R20 dB showed an improvement of 50 and 33% for CF and CF+DAS beamformers, respectively, with PSA as compared to PHA. In addition, simulation results validated the effectiveness of PSA versus PHA.
  
  
  CONCLUSIONS
  In applications where there are no important limitations on the SNR, PSA imaging is recommended as it increases the ability of the receive beamformer for better focusing.
authors: Department of Biomedical Engineering, Tarbiat Modares University, Ale-Ahmad Avenue, P.o. Box: 14115-194, Tehran, Islamic Republic of Iran.
authors: Masume
authors: M
authors: Sadeghi
authors: Department of Biomedical Engineering, Tarbiat Modares University, Ale-Ahmad Avenue, P.o. Box: 14115-194, Tehran, Islamic Republic of Iran. mahlooji@modares.ac.ir.
authors: Ali
authors: A
authors: Mahloojifar
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D003560:Cysts / Q000000981:diagnostic imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008962:Models, Theoretical; D014463:Ultrasonography / Q000379:methods*
keywords: Coherence factor; Delay and sum; Effective aperture; Phased synthetic aperture imaging