A framework for the simulation and validation of acoustic fields from medical ultrasound transducers

Abstract

The unified simulation framework for medical ultrasound, FieldSim, cur- rently supports linear and non-linear simulations by using Field II and Aber- sim, respectively. In this thesis the quasi-linear simulation tool, Propose, is incorporated in FieldSim and verified. The implementation uses Field II to generate the initial pressure propagated by Propose. It is shown to pro- duce satisfactory results when compared to standalone Propose, Field II and Abersim for both the fundamental and second harmonic. The results are also verified in the water tank. The running time is found to be slower than standalone Propose, but still substantially quicker than Abersim for non-linear simulations. By combining core features of the FieldSim frame- work and Propose new features are presented. It is now possible to easily simulate the second harmonic from a transducer with a measured impulse response and arbitrary excitation pulse using Propose in minutes, compared to hours with Abersim. By rotating the initial field steering can now be achieved in Propose in few lines of MATLAB code. A link between a research scanner and the FieldSim framework is pre- sented. When finalized a FieldSim simulation can be converted to a file read by PyTexo making it possible to use the exact same setup for both simu- lations and measurements in the water tank. The current implementation supports single ultrasound beams and B-mode with fixed focus.