Huygens on speed: Interactive simulation of ultrasound pressure fields

The introduction of graphics processing unit (GPU) computing has made it possible to speed up computationally demanding algorithms. One of these algorithms is the calculation of pressure fields from acoustic transducers. Here, the execution time often limits the number of elements and field points we can select in order to get results back in finite time. In this paper we present a simple GPU-based simulator capable of simulating high resolution pressure fields at interactive frame rates. The simulator is based on the same principle as the Ultrasim toolbox, where responses from several point sources are accumulated in a set of observation points, hence solving the Rayleigh-Sommerfeld integral. The cumulative sum for each observation point is independent of all other observation points, making the problem perfect for GPU processing. For the simulator we provide both a Paint-like interface for interactive drawing of uniform linear arrays and free-hand shapes, and a Matlab interface for precise scripting of element positions and observation points. The presented GPU simulator was compared both with a multi threaded C-version, Ultrasim, and Field II. Compared with Ultrasim we report a 400 times speedup when simulating a varying number of source points on a 150 K points observation grid. The test system consisted of a low-end GPU (Nvidia Quadro 600) and an Intel i7-870 2.93 GHz quad-core CPU.