Browsing by Subject "High intensity focused ultrasound"

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Frequency optimization in high intensity focused ultrasound
    (IEEE, 2014-09) Yetik, H.; Arıyurek, Cemre; Bozkurt, A.; Ergun, A. S.
    In high intensity focused ultrasound (HIFU) the choice of transducer frequency depends on the target depth and tissue type. At high frequencies attenuation does not permit enough acoustical power to be transmitted to the target whereas at low frequencies the transmitted power is not absorbed efficiently. Hence, there exists an optimum frequency at which the power deposited at the target is maximum. In this study, we verified this relation experimentally using MR compatible focused transducers, ex-vivo tissue samples and magnetic resonance (MR) thermometry. © 2014 IEEE.
  • Thumbnail Image
    ItemOpen Access
    Intelligent controlling microbubble radial oscillations by using Slave-Master Feedback control
    (Elsevier Inc., 2014) Behnia, S.; Yahyavi, M.; Mobadersani F.
    Dynamics of acoustically driven microbubbles in ultrasonic fields are known to be complex and uncontrollable phenomena indicative of a highly active nonlinear as well as chaotic behavior. In this paper, a method based on Slave-Master Feedback (SMF) to suppress unstable radial oscillations of contrast agents is presented. In the proposed control process, the encapsulated microbubbles as the slave system is coupled with a dynamical system as the master, so that the output of the coupled system is able to produce a stable oscillation. A great virtue of this control technique is its flexibility. In comparison with existing techniques, the present dynamical chaos control method does not need to know more than one variable. The numerical results show its strong impact on reducing the chaotic oscillations to regular ones. © 2014 Elsevier Inc. All rights reserved.