Gain deep access to raw imaging data for offline analysis
Digital RF-Mode allows users to acquire, digitize, and export the raw RF data from the ultra-high frequency ultrasound signal. Transducers convert electrical energy into a pressure wave which is transmitted into the tissue (transmitted pulse). Differences in the density and speed of sound within tissue scatter the transmitted pulses, such that a portion of the sound waves reflect back towards the transducer. When these reflected waves reach the transducer they are converted into an electrical signal which is amplified, digitized, and processed to generate the displayed image. The signal received by the transducer is composed of a number of reflections which combine together to form an interference pattern known as speckle. This received signal is commonly referred to as an RF (radio frequency) signal. After amplification, the received signal is sampled to convert it to a digital signal, and subsequently processed by the beamformer in order to display a final image on the screen.
Available Data Formats
Quadrature sampling is used to convert the RF signal into two digital quadrature signals - the I (in-phase) and the Q (quadrature) signals, referred to collectively as the IQ signal. The beamformer processes data which is in the IQ format.
If required, a digital representation of the RF signal can be reconstructed from the IQ data. This is accomplished through interpolation of the I and Q signals and multiplication by a complex exponential (e-jωt where ω=2πf; f= the quadrature sampling frequency and e-jωt= cos (2πf) + jsin (2πf)).
Raw Image Data
IQ data can be envelope-detected and log compressed, then be exported as a raw data file (*.RAW). The envelope format is a useful way of storing raw data that correlates exactly to what is seen in the B-Mode image and is readily available for image processing applications.