THE DISTRIBUTION OF THE LOCAL ENTROPY IN ULTRASOUND IMAGES

In this article, a model for the amplitude statistics of the backscatt ered ultrasonic signal is presented, We propose to view a tissue as be ing composed of a large number of small units, each having slightly di fferent characteristics. This variability within the tissue is express ed by fluctuations in the parameters of the local probability distribu tion function (PDF), Based an analogous expressions derived for radio propagation and optical scintillations, the local PDF is modulated by a lognormal distribution of the local standard deviation, Integrating the local contributions yields the amplitude PDF for the entire tissue , We show that the local entropy is a normal variable, since for four different local PDFs it is linearly related to the logarithm of the lo cal standard deviation, When the local entropy histogram exhibits dist inct and multiple peaks, the local entropy distribution can be used fo r region segmentation, This fact is demonstrated for ultrasonic images of ovarian cysts.