Ultrasound Receive-Side Strategies for Image Quality Enhancement in Low-Energy Illumination Based Photoacoustic Imaging

PAT (Photoacoustic Tomography) is a hybrid noninvasive imaging modality that provides functional cum structural information about the underlying tissue medium. Conventional PAT employs bulky and expensive solid-state pulsed lasers as an illumination source, however, Light Emitting Diodes (LED) and Pulsed Laser Diodes (PLD) have been recently explored as a suitable alternative that are portable and inexpensive. However, its depth of penetration is relatively lower than that of solid-state lasers due to lower energy per pulse. Averaging of multiple frames is usually employed as a common practice in high PRF LED/PLD systems to improve the PAT image SNR. Recently an approach of sub-pitch translation of ultrasound linear array was demonstrated to contribute to improvement in SNR of PAT image, with just fewer number of frame averaging. In this chapter, the various methods proposed in literature for improving the achievable image SNR in low energy LED/PLD based PAT systems are described. Specifically, details of the simulation and experimental studies conducted using sub-pitch translation approach are provided. Overall, this chapter briefly summarizes the reports that demonstrate feasibility of achieving improvement in image quality by employing novel methods at receive-side (ultrasound data acquisition and beamforming) while using low energy sources of illumination in PAT.