This study was to optically visualize the cavitation bubbles produced by a clinical shock wave and to look into their geometric features of the resulting cavitation bubbles in relation to the driving shock wave field. A clinical shock wave therapeutic system was taken for shock wave production. The shock wave induced cavitation bubbles were captured by a professional camera under the illumination of a micro-pulse LED light. The light exposure was set to last for the whole life time of bubbles from formation to subsequent collapses. It was shown that the cavitation bubbles appeared mostly in the vicinity of the focus. The bubbles became more and larger as approaching to the focus. The cavitation bubbles formed jet streams which became enlarged (stronger) as the shock wave device output setting increased. The bubble cloud boundary was reasonably fitted to an elongated ellipsoid characteristically similar to the acoustic focal area. The bubble clouds were enlarged as the output setting increased. The geometric features of the cavitation bubbles characteristically similar to those of the focusing acoustic field have potential to provide the therapeutic focal information without time consuming hydrophone measurements of the shock wave field causing damages of the expensive sensor. The present study is limited to the static afterimages of the cavitation bubbles and investigation including the bubble dynamics is suggested to deliver the more realistic therapeutic area of the shock wave therapy.
Acoustics ; Afterimage ; Lighting ; Rivers ; Shock*

Palinopsia means a visual image persisting for minutes to hours or reappearing episodically after the exciting stimulus has been removed. The anatomic correlation of palinopsia is not clear, whereas occipito-parietal and occipito-temporal lesions have been implicated. We describe a patient presenting palinopsia prior to motor seizures which was related to left posterior temporal lesion. A 36-year-old man had a generalized tonic clonic seizure after palinoptic positive visual afterimages. Brain MRI and Transfemoral cerebral angiography (TFCA) revealed an arteriovenous malformation of 1x1.5x2 cm3. We used oxcarbazepine for preventing recurrent seizures and planned gamma knife radiosurgery. Palinopsia is a very rare clinical manifestation as an aura of seizures. Palinopsia preceding clinical seizure as a localizing value, so that neuroimaging is mandatory in this clinical situation. This is the first reported case of palinopsia in Korea.
Afterimage ; Arteriovenous Malformations ; Brain ; Carbamazepine ; Cerebral Angiography ; Epilepsy ; Humans ; Korea ; Neuroimaging ; Radiosurgery ; Seizures ; Visual Perception