[Paper Review] SIMUS: an open-source simulator for ultrasound imaging. Part I: theory & examples

Damien Garcia|arXiv (Cornell University)|Feb 4, 2021

Ultrasound Imaging and Elastography34 references4 citations

TL;DR

SIMUS is an open-source, Matlab-based ultrasound simulator designed for rapid, pedagogical, and research-oriented simulation of ultrasound imaging using far-field and paraxial approximations. It enables efficient computation of acoustic pressure fields and RF signals for linear and convex probes, offering a user-friendly, frequency-domain tool with comprehensive theoretical foundations and open-source code under the LGPL license.

ABSTRACT

Computational ultrasound imaging has become a well-established methodology in the ultrasound community. Simulations of ultrasound sequences and images allow the study of innovative techniques in terms of emission strategy, beamforming and probe design. There is a wide spectrum of software dedicated to ultrasound imaging, each having its specificities in its applications and in the numerical method. I describe in this two-part paper a new ultrasound simulator (SIMUS) for Matlab, which belongs to the Matlab UltraSound Toolbox (MUST). The SIMUS software is based on far-field and paraxial approximations. It simulates acoustic pressure fields and radiofrequency RF signals for uniform linear or convex probes. SIMUS is an open-source software whose features are 1) rapidity, 2) ease of use, 3) frequency domain, 4) pedagogy. The main goal was to offer a comprehensive turnkey tool, along with a detailed theory for pedagogical and research purposes. This first part of the paper describes in detail the underlying linear theory of SIMUS and provides examples of simulated acoustic fields and ultrasound images. The second part is devoted to the comparison of SIMUS with popular software: Field II, k-Wave, and the Verasonics simulator. The Matlab open codes for the simulator SIMUS are distributed under the terms of the GNU Lesser General Public License, and can be downloaded from this https URL.

Motivation & Objective

• To develop a fast, easy-to-use, and pedagogically oriented ultrasound simulator for research and education.
• To provide a comprehensive, open-source tool based on linear acoustic theory for simulating ultrasound imaging sequences.
• To enable rapid prototyping of new emission strategies, beamforming techniques, and probe designs through accurate simulation.
• To offer a turnkey solution with detailed theoretical background and accessible code for researchers and students.
• To facilitate comparison with established simulators like Field II, k-Wave, and Verasonics through standardized benchmarks.

Proposed method

• The simulator uses far-field and paraxial approximations to model the propagation of ultrasound waves from transducer elements.
• It computes acoustic pressure fields in the frequency domain using analytical solutions based on the Rayleigh integral and Huygens' principle.
• Radiofrequency (RF) signals are synthesized by back-projecting the pressure field to simulate received signals at the transducer.
• The framework supports both uniform linear and convex array probes with customizable element geometry and excitation parameters.
• The implementation is optimized for speed and integrates seamlessly within the Matlab environment using vectorized operations.
• The code is released under the GNU Lesser General Public License, enabling reuse, modification, and distribution with full transparency.

Experimental results

Research questions

• RQ1 How accurately can SIMUS simulate acoustic pressure fields and RF signals for different probe configurations using paraxial approximations?
• RQ2 What is the performance gain of SIMUS in terms of simulation speed compared to established ultrasound simulators like Field II, k-Wave, and Verasonics?
• RQ3 To what extent does SIMUS support pedagogical understanding of ultrasound beamforming and emission strategies?
• RQ4 How does the open-source nature of SIMUS enhance reproducibility and extensibility in ultrasound research?
• RQ5 Can SIMUS effectively simulate complex imaging sequences while maintaining computational efficiency and theoretical fidelity?

Key findings

• SIMUS enables fast and accurate simulation of ultrasound pressure fields and RF signals using analytical models based on far-field and paraxial approximations.
• The simulator is optimized for speed and ease of use, making it suitable for real-time prototyping and educational applications.
• The open-source release under the LGPL license ensures full transparency, reproducibility, and extensibility for the research community.
• SIMUS provides a comprehensive theoretical foundation that supports pedagogical use and in-depth understanding of ultrasound imaging physics.
• The software is designed as a turnkey solution with integrated documentation and example scripts for immediate use in research and teaching.
• The second part of the paper demonstrates that SIMUS performs comparably to established simulators such as Field II, k-Wave, and Verasonics in key simulation tasks.