A new acoustic lens material for large area detectors in photoacoustic breast tomography

Acoustic lenses made of acrylic plastic (PMMA) have been used to enlarge the acceptance angle of sensitive large surface area detectors and improve lateral resolution. However, PMMA lenses introduce image artifacts due to ultrasound internal reflections within the lenses. In this work we investigated this issue proposing a new lens material Stycast 1090SI. We characterized the acoustic properties of the proposed material in comparison with PMMA. Detector performance using negative lenses with the two materials, was tested using finite element simulation and experiment. Further the image quality of a photoacoustic tomography system was studied using k-Wave simulation and experiment. Our acoustic characterization showed that Stycast 1090SI has tissue-like acoustic impedance, high speed of sound and low acoustic attenuation. Both acoustic lenses show significant enlargement of detector acceptance angle and lateral resolution improvement. However, image artifacts induced by acoustic lenses are reduced using the proposed lens compared to PMMA lens.