Real-time photoacoustic data acquisition with Philips iU22 ultrasound scanner

Abstract

A one of a kind photoacoustic system has been built around a Philips iU22 ultrasound scanner. The modified channel board architecture allows access to the raw per-channel photoacoustic data, while keeping all of the imaging capabilities of an actual commercial ultrasound scanner. A captured photoacoustic data frame is Fourier beamformed to generate a single laser shot photoacoustic image. In addition to the photoacoustic data, the system supplies the beamformed ultrasound data, providing a truly dual-modality imaging capability. A tunable OPO laser system (700-900nm), pumped by an Nd:YAG solid state laser, is used as an illumination source with 5ns long pulses. An FPGA-based electronic board synchronizes the iU22 start of frame with the laser firing, currently permitting photoacoustic imaging at a rate of 10 Hz (laser repetition rate limit). At that imaging frame rate the photoacoustic system, consisting of a PC modified with 32 Gbytes of acquisition memory and an FPGA array, is able to store several minutes of continuously captured data, enabling monitoring and off-line analysis of dynamic photoacoustic events and/or fast scanning for performing pseudo-3D imaging. The system can use all of the standard iU22 array transducers both for photoacoustic imaging, and in all of the ultrasound imaging modes.