Cloud cavitation control for lithotripsy using high intensity focused ultrasound.

Cloud cavitation is potentially the most destructive form of cavitation. When the cloud cavitation is acoustically forced into a collapse, it has the potential to concentrate a very high pressure, more than 100 times the acoustic pressure, at its center. We experimentally investigate a method to control the collapse of high intensity focused ultrasound (HIFU)-induced cloud cavitation to fragment kidney stones.

Tissue distribution of Thorotrast and role of internal irradiation in carcinogenesis.

Carcinogenesis in Thorotrastosis has been assumed due to direct bombardment by alpha-particle with high linear energy transfer during decay of 232Th. To revisit the mechanism of carcinogenesis by Thorotrast (THR), we examined the tissue distribution of THR granules and two-dimensional distribution of radioactivity in the organs of Thorotrastosis patients and studied their spatial relationship to histopathological changes. The high radioactivity in the patients' organ was predominantly derived from decay of Thorium series and showed unique distribution, while the far lower natural radioactivity was mainly from Uranium series decay and fairly evenly distributed.