A Focused Ultrasound System for Tissue Volume Ablation in Deep Seated Brain Sites

Abstract

A b s t r a c t : A new i n t e n s e focused u l t r a s o u n d system o p e r a ti n g i n t h e transcutaneous mode has been c o n s t r u c t e d f o r s t u d y o f i t s u t i l i t y i n t h e t r e a t m e n t o f deep seated b r a i n tumors i n t h e human. I n p r e p a r a t i o n f o r t r e a t m e n t t h e human w i l l have s u r g i c a l removal o f an a p p r o p r i a t e s k u l l s e c t i o n and t h e o v e r l y i n g t i s s u e s w i l l be l e f t t o heal b e f o r e s t a r t i n g t h e i r r a d i a t i o n process. t r e a t m e n t w i l l be done w i t h CT scanning i n v o l v i n g a r i g i d l i g h t w e i g h t s k u l l f i x a t i o n f i x t u r e which remains r i g i d l y a t t a c h e d t o t h e p a t i e n t ' s s k u l l f o r t h e CT scan as w e l l as f o r t h e i r r a d i a t i o n procedure. Once t h e l e s i o n volume c o o r d i n a t e s a r e determined and t h e p a t i e n t i s a t t a c h e d t o t h e i r r a d i a t i o n system t h e 1 MHz focused beam i s a u t o m a t i c a l l y b r o u g h t t o an a r r a y o f p o s i t i o n s w i t h i n t h eI. I n t r o d u c t i o n : Focused u l t r a s o u n d has been used t o produce b r a i n l e s i o n s i n experimental animals and i n humans d u r i n g c l i n i c a l s t u d i e s . These s t u d i e s have demonstrated t h e a b i l i t y o f u l t r a s o u n d t o focus e s s e n t i a l l y a t any p r e s e l e c t e d b r a i n s i t e and t o ab1 a t e t h e t i s s u e r e s t r i c t e d t o t h e se1 e c t e d f o c a l s i t e . Because o f s k u l l bone impediment t o u l t r asound t r a n s m i s s i o n s most o f t h e s t u d i e s have been performed w i t h s k u l l bone removed, and t h e i r r a di a t i o n p e r f o m e d t r a n s d u r a l l y o r t

Numerical study of a simple transcranial focused ultrasound system applied to blood-brain barrier opening

“…Phase aberrations caused by discrepancies in sound velocity as well as high absorption can rapidly yield poor focusing and higher energy loss, especially at higher ultrasound frequencies [19], [20]. …”

The potential of transskull ultrasound therapy and surgery using the maximum available skull surface area

“…One of the potential applications of focused ultrasound is for brain therapy and surgery. Since the early experiments of Fry et al, [6][7][8][9][10] it has been known that the human skull strongly attenuates and distorts ultrasoundbeam propagation, and that transskull ultrasound therapy and surgery may be possible but difficult. Smith et al introduced the phased-array technique to ultrasound diagnostic imaging in order to correct the beam degradation due to the presence of intervening bone.…”

Clinical applications of focused ultrasound—The brain

“…This series had a small number of patients and the results were inconclusive. A more advanced CT-guided system was developed later but was not clinically tested [21].…”