Design and in vitro results of a high intensity ultrasound interstitial applicator.
Interstitial technologies were proposed for the treatment of deep-seated and unresectable tumours. This study was designed to demonstrate the possibility of producing coagulation necrosis for a short exposure duration (20s) and a large volume with an interstitial ultrasonic applicator equipped with a plane transducer. The applicator was evaluated in terms of electroacoustic efficiency (58% at 10.7 MHz), temperature pattern and in vitro pig liver tissues destruction. The temperature elevation reached 52, 39, 22 and 15 degrees C at, respectively, 2.5, 7.5 and 10 mm from the applicator surface along the propagation axis. The evident cigar-shaped lesions spread on a depth of (8 +/- 2) mm from the surface applicator, (10 +/- 1) mm high and (3 +/- 1) mm high and (3 +/- 1) mm wide. The temperature measurements showed the limitations encountered with a 10 MHz transducer. The high increase in temperature of tissues close to the transducer can induce vaporisation and a gaseous barrier opaque to ultrasound. Owing to the shape and the operating frequency of the transducer, we hope to obtain the same satisfactory performances in vivo with weakly perfusion-dependent lesions. Axial and longitudinal applicator motions will enable us to treat more important volumes.
Lafon
C
C
INSERM, Unité 281, 151 Cours Albert Thomas, Lyon, France. lafon@lyon151.inserm.fr
Chapelon
J Y
JY
Prat
F
F
Gorry
F
F
Theillère
Y
Y
Cathignol
D
D
D000162:Acoustics; D000818:Animals; D004560:Electricity; D004867:Equipment Design; D005069:Evaluation Studies as Topic; D005740:Gases; D006358:Hot Temperature; D006979:Hyperthermia, Induced; D008099:Liver / Q000473:pathology; D009336:Necrosis; D009374:Neoplasms, Experimental / Q000628:therapy; D013552:Swine; D013997:Time Factors; D014159:Transducers; D014464:Ultrasonic Therapy / Q000295:instrumentation*; D014835:Volatilization
D005740:Gases