*Article* **A Single Simulation Platform for Hybrid Photoacoustic and RF-Acoustic Computed Tomography**

#### **Christopher Fadden 1 and Sri-Rajasekhar Kothapalli 2,3,***∗*


Received: 3 July 2018; Accepted: 29 August 2018; Published: 6 September 2018

**Abstract:** In recent years, multimodal thermoacoustic imaging has demonstrated superior imaging quality compared to other emerging modalities. It provides functional and molecular information, arising due to electromagnetic absorption contrast, at ultrasonic resolution using inexpensive and non-ionizing imaging methods. The development of optical- as well as radio frequency (RF)-induced thermoacoustic imaging systems would benefit from reliable numerical simulations. To date, most numerical models use a combination of different software in order to model the hybrid thermoacoustic phenomenon. Here, we demonstrate the use of a single open source finite element software platform (ONELAB) for photo- and RF-acoustic computed tomography. The solutions of the optical diffusion equation, frequency domain Maxwell's equations, and time-domain wave equation are used to solve the optical, electromagnetic, and acoustic propagation problems, respectively, in ONELAB. The results on a test homogeneous phantom and an approximate breast phantom confirm that ONELAB is a very effective software for both photo- and RF-acoustic simulations, and invaluable for developing new reconstruction algorithms and hardware systems.

**Keywords:** photoacoustic imaging; tomography; thermoacoustic; radio frequency
