Attenuation estimation with the zero-crossing technique: phantom studies

Global and local attenuation coefficient estimations were performed in a phantom using a pulse echo method based on the rate of decay of zero crossing density. Focussed and unfocussed 3.5 MHz transducers were used. It was found that good global estimates could be made with either transducer over a 2:1 range of attenuation coefficient. Local estimates exhibit large bias errors and a high degree of variability. This variability diminishes in the focal zone of the focussed transducer and in the far field of the unfocussed transducer.