Non-Rayleigh statistics of ultrasonic backscattered signals.

The statistics of the envelope of the backscattered signal from tissues have been known to vary from the well-known Rayleigh model. The K-distribution is used to model this non-Rayleigh behavior, since the generalized K-distribution encompasses a wide range of distributions like Rayleigh, Lognormal, and Rician. Computer simulations were conducted using a simple one-dimensional discrete scattering model to investigate the properties of the echo envelope. Significant departures from Rayleigh statistics were seen as the scattering cross sections of the scatterers became random. The validity of this model was also tested using data from tissue mimicking phantoms. Results indicate that the density function of the envelope can be modeled by the K-distribution and the parameters of the K-distribution can provide information on the nature of the scattering region in terms of the number as well as the scattering cross sections of the scatterers.