Ct usually demonstrates a high attenuation region surrounded by a halo of abnormally low attenuation, consistent with acute hemorrhage and secondary edema, respectively.

Assuming a trilinear geometrical spreading model, we obtained the attenuation function in Guangdong region.

Objective the variations of the site and shape of focal region for a concave spherical ultrasound transducer in the case of high sound intensity and stronger attenuation were studied.