Photoacoustic-based thermal imaging using LED illumination

• Grant number: 22/08495-8
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2022
• End date: July 31, 2023
• Field of knowledge: Engineering - Biomedical Engineering - Medical Engineering
• Principal Investigator: Theo Zeferino Pavan
• Grantee: Lara Zanello Pires
• Host Institution: Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil
• Associated research grant: 21/06728-2 - Photoacoustic and ultrasound imaging for theranostic purposes, AP.JP2

Abstract

Photoacoustic image is an imaging technique based on the photoacoustic effect, which refers to the generation of acoustic waves due to the absorption of electromagnetic energy. The photoacoustic signal magnitude depends on the absorption of light energy and, in addition to optical properties, is also dependent on the mechanical and thermal properties of tissue. The thermal coefficient of volume expansion and the speed of sound are directly related to the amplitude of the sound wave emitted by the photoacoustic effect and are a function of the material's temperature. Thus, the acquisition of photoacoustic images can be a non-invasive way of monitoring the temperature of biological tissue when submitted to hyperthermia treatment. In previous studies, our research group developed an algorithm to generate photoacoustic-based thermal images. This algorithm was evaluated with our custom-designed photoacoustic imaging system composed of a Nd:YAG laser system, which is capable of generating 10 frames per second. Additionally, with this system we are only capable of creating the photoacoustic images with offline processing; therefore, limiting the possibility of creating real-time photoacoustic-based thermal images. In the present research project, a commercial photoacoustic imaging system, where high-power LEDs are responsible for tissue illumination, will be used to obtain the photoacoustic-based thermal images. This system is capable of creating up to 4000 frames per second and displaying photoacoustic images in real-time. In this research project, we aim to adapt the photoacoustic-based thermal imaging methods previously created by our group to be used with a commercial LED-based system. Therefore, we will evaluate the feasibility of generating the thermal images using LED illumination. The proposed technique will be evaluated with phantoms immersed in a water bath at a controlled temperature and during the magnetic hyperthermia procedure.