Threshold dosages for damage to mammalian liver by high intensity focused ultrasound

The threshold dosages for high-intensity focal lesion production were determined at 3 MHz in the cat liver for exposure durations covering the range 0.003-35 s. The liver threshold was found to parallel that for the brain over the range of exposure durations 0.1 to 10 s, but to be more than twice the intensity level, approximately following the relation IT(0.5)=460 W-cm(2)/s(2), where I is the peak intensity and T is the exposure duration. At shorter exposure durations the threshold curve deviates from this relation, probably due to a change to a transient cavitation mechanism of damage.