title: Effect of the secondary process on mass point vibration velocity propagation in magneto-acoustic tomography and magneto-acousto-electrical tomography.
abstract: BACKGROUND
  As two of the new biological electrical impedance tomography (EIT), magneto-acoustic tomography (MAT) and magneto-acousto-electrical tomography (MAET) achieve both the high contrast property of EIT and the high spatial resolution property of sonography through combining EIT and sonography. As both MAT and MAET contain a uniform magnetic field, vibration and electrical current density, there is a secondary process both in MAT and in MAET, which is MAET and MAT respectively.
  
  
  OBJECTIVE
  To analyze the effect of the secondary process on mass point vibration velocity (MPVV) propagation in MAT and MAET.
  
  
  METHODS
  By analyzing the total force to the sample, the wave equations of MPVV in MAT and MAET - when the secondary processes were considered - were derived. The expression of the attenuation constant in the wave number was derived in the case that the mass point vibration velocity propagates in the form of cylindrical wave and plane wave. Attenuations of propagation of the MPVV in several samples were quantified.
  
  
  RESULTS
  Attenuations of the MPVV after propagating for 1 mm in copper or aluminum foil, and for 5 cm in gel phantom or biological soft tissue were less than 1%.
  
  
  CONCLUSIONS
  Attenuations of the MPVV in MAT and MAET due to the secondary processes are relatively minor, and effects of the secondary processes on MPVV propagation in MAT and MAET can be ignored.
authors.affiliation: Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing, China.|University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Zhishen
authors.initials: Z
authors.lastname: Sun
authors.affiliation: Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing, China.
authors.forename: Guoqiang
authors.initials: G
authors.lastname: Liu
authors.affiliation: Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing, China.|University of Chinese Academy of Sciences, Beijing, China.|College of Control Theory and Engineering, China University of Petroleum, Qingdao, Shandong, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Guo
authors.affiliation: Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Xia
authors.affiliation: Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing, China.
authors.forename: Xinli
authors.initials: X
authors.lastname: Wang
mesh_terms: D000162:Acoustics; D000465:Algorithms; D017097:Electric Impedance; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D014054:Tomography / Q000379:methods*; D014463:Ultrasonography / Q000379:methods*; D014732:Vibration / Q000627:therapeutic use*
keywords: Magneto-acoustic tomography; linear damping; magneto-acousto-electrical tomography; wave equation of mass point vibration velocity