Ultrasonic tissue characterization

Reflected ultrasonic single from soft tissue are examined to determine the acoustic parameters which discriminate between healthy and diseased tissues, and their temperature and frequency dependence. The velocity, the attenuation coefficient, and the slope of the acoustic attenuation with frequency in plexiglass, bovine liver, normal breast and cancer breast specimens are measured over a frequency range from 0.8-4 MHz. Human female breast is examined both histologically and acoustically. It is found that the attenuation in soft tissues is strongly dependent on the temperature and transducer's frequency. It is also found that the acoustic velocity does not vary strongly with frequency for plexiglas, bovine liver and normal breast specimens, however, it varies significantly for cancer breast specimens. Also, the acoustic velocity is found to be temperature dependent. Pathological tissues are found to have higher attenuation and velocity compared to that for normal breast tissues

Investigation of a model for estimating the attenuation of ultrasonic signals

mathematical model is developed to simulate attenuation of soft tissues. A comparison is done between the results of linear model [zero phase and minimum phase] and nonlinear model. The nonlinear minimum phase model is verified to be the best model for simulating the attenuation of ultrasound in soft tissues, as compared to the zero phase and the minimum phase linear models