Colloquium - February 6 - Characterization of shear acoustic properties of human skull bone
Presenter: Dr. Samuel Picardo
Ph.D., Scientist, Thunder Bay Regional Research Institute
Adjunct Professor, Electrical Engineering, Physics, Lakehead University
In this talk I will present our last results on the characterization of the acoustic properties of human skull samples. A numerical method based on a staggered FDTD solution of the viscoelastic sound equation was used to carry out simulations of transcranial ultrasound transmission. This method was implemented using GPUs to facilitate its use in optimization studies. The numerical method was validated with hydrophone measurements of ultrasound transmission through plastic plates of different types mimicking dimensions of the skull bone. A genetic optimization method was executed to establish the functions of shear speed of sound and attenuation linked to apparent density information calculated from CT scans. To make converge the solution, the optimization method compared the prediction of transmitted acoustic fields to experimental measurements with hydrophone in the presence of skull samples and with incidence angle of 40 degrees. Ultrasound transmission was executed in narrow-band conditions at frequencies of 270 kHz and 836 kHz.
The results in this study shows the high degree of variability specimen to specimen in the transmitted acoustic fields and a strong dependency to the specific density information and ultrasound frequency. The numerical method and the optimal functions of shear speed sound and attenuation produced an accurate prediction of the transmitted acoustic fields. These results and numerical method will help to better understand sound transmission through the human skull and will have important implications in the optimal development of imaging and therapeutic applications of ultrasound in the brain.