ABSTRACT
This chapter discusses the acoustic properties of the skull, and the challenges that are faced when seeking to image the brain, through the skull. Ultrasonics has found usage in all aspects of the medical field, including diagnostic, therapeutic, and surgical applications. Ultrasonic wave propagation in body tissues is, in large measure, controlled by working in combination with acoustic impedance contrast at boundaries and the various weaker scattering mechanisms that occur at the different size scales found within tissues velocity and attenuation factors. Focused high-intensity ultrasonic energy can produce permanent changes deep within tissue without adversely affecting intervening intact structures. The intensity of the ultrasonic energy used in medical applications can be measured calorimetrically, by absorption probes, or by radiation pressure gauges calibrated in watts. The use of ultrasonic therapy in the epiphyseal area of growing bone has been viewed with caution because high-intensity ultrasound was believed to cause damage to bone cortex and bone marrow.
