“Receive-only” reconstruction, for imaging one-way acoustic emissions

Verasonics provides example scripts that modify the beamformer to only consider the one-way travel time from every point in the medium to the array, as is the case in Photoacoustic imaging.

16-bit ADC and 125 MHz sampling rate

The Vantage NXT platform utilizes a 500 MHz master clock, which enables the system to handle a maximum ADC rate of 125 MHz. A sampling rate of 125 MHz enables reception of signals containing frequencies of up to 60 MHz on each channel across a maximum of 256 total channels. In addition, the Vantage NXT has a 16-bit ADC, which has finer quantization levels. These two features provide a much wider dynamic range suitable for recording weak PA signals.

Programmable hardware synchronization with laser sources

The Vantage NXT system provides 4 programmable input and output triggers that are accurate to within one sample interval (RF sampling period). They are software programmable to occur anywhere in the acquisition sequence, and thus, the system can be repeatedly triggered by the laser source. In Vantage NXT, the trigger OUT signal’s pulse duration can be set to 1 μs, 100 μs, 1 ms, or 10 ms with an active low or active high 3.3 V or 5 V amplitude signal. Further, the Trigger IN and Trigger OUT signals are configurable to one of the 4 connectors available on the front and back panel of the hardware unit. This feature simplifies synchronization with diverse laser sources.

Float16 datatype

On all Vantage NXT systems, a half datatype, also known as the float16 datatype, can be utilized for storing RF data in addition to the existing int16 datatype. The half datatype can represent the full 22 bits of output (after scaling) from the multi-rate filter. This feature allows for improved SNR and better detection of weak photoacoustic signals.

Digital control on TGC

Rcvprofile.digitalTGC is a programmable parameter in the Vantage NXT system that disables the analog TGC waveform control and replaces it with a fixed TGC setting that will remain constant throughout the receive data acquisition interval. This feature helps improve photoacoustic receive path sensitivity by eliminating the added signal noise injected by the analog TGC control signal.

Application scripts provided in the Verasonics Community portal

The system offers researchers the flexibility to modify their script according to the triggering needs of different lasers. As an example, we have provided two example scripts that demonstrate how to synchronize the Vantage/Vantage NXT with a solid-state laser that requires a trigger OUT pulse and a pulsed laser diode that does not require a trigger OUT pulse. These example scripts can be found in the Verasonics Community Portal.  

Fig 1. This figure shows the ultrasound (left) and the overlaid photoacoustic (right) images of the common femoral artery (CFA) of a healthy volunteer. This data was acquired at the Erasmus Medical Center, Rotterdam, Netherlands, in collaboration with Professor Gijs van Soest and Dr. Francis Joseph Kalloor.

(Published article: https://www.sciencedirect.com/science/article/pii/S0301562925001905)