It is Breast cancer screening with ultrasound. Ultrasound imaging is based on Acoustic impedance ( a product of the density of the observed tissue and the ultrasound velocity along that tissue). It looks for shape, texture. It detects whether a lump is maligant mass or a benign cyst. It can also be used for screening & diagnosis. This is a safer procedure with very low power and very short exposition mechanical waves. It is the best for dense breast.