DocumentCode :
1251731
Title :
Ultrasound applicators for interstitial thermal coagulation
Author :
Diederich, Chris J. ; Nau, William H. ; Stauffer, Paul R.
Author_Institution :
Dept. of Radiat. Oncology, California Univ., San Francisco, CA, USA
Volume :
46
Issue :
5
fYear :
1999
Firstpage :
1218
Lastpage :
1228
Abstract :
Direct-coupled (DC) and catheter-cooled (CC) ultrasound applicator configurations were evaluated for high-temperature ultrasound interstitial thermal therapy (USITT) using computer simulations, acoustic beam measurements, and in vivo temperature measurements. The DC devices consist of 2.2-mm diameter tubular ultrasound transducers encapsulated within a thin biocompatible plastic coating, which can be inserted directly into the tissue. The CC devices incorporate 1.5-mm diameter tubular transducers, which are inserted within 2.2to 2.4-mm diameter plastic implant catheters and require an integrated water-cooling scheme. Simulated transient temperature profiles and cumulative thermal dose distributions indicate that each of these applicator configurations can produce target temperatures greater than 50/spl deg/C and corresponding thermal doses greater than 300 to 600 equivalent minutes at 43/spl deg/C (EM/sub 43/spl deg/C/) within 5 min at a radial depth of 1 to 1.5 cm in moderately perfused tissues. Theoretical investigations of air-cooling implemented within DC applicators demonstrated a significant enhancement of thermal penetration compared with non-cooled DC applicators, thus approaching performance attainable with CC devices. Temperature distributions achieved with DC and CC applicators in vivo were in agreement with theoretical calculations and further demonstrate that the devices are practical, sufficient power output levels can be obtained, and the angular heating profiles can be shaped or directed to protect non-targeted critical normal tissues. This preliminary study demonstrates that these interstitial ultrasound applicators have potential to provide controlled thermal coagulation and necrosis of small target regions and deserve further investigation and development for possible implementation in the treatment of benign and cancerous lesions in sites such as prostate, liver, and brain.
Keywords :
biomedical transducers; biomedical ultrasonics; hyperthermia; temperature distribution; tumours; 1.5 mm; 2.2 mm; 43 C; 5 min; 50 C; acoustic beam measurements; angular heating profiles; benign lesions; biocompatible plastic coating; brain; cancerous lesions; catheter-cooled configurations; computer simulations; controlled thermal coagulation; cumulative thermal dose distributions; direct-coupled configurations; in vivo temperature measurements; integrated water-cooling scheme; interstitial thermal coagulation; liver; miniature applicators; moderately perfused tissues; necrosis of small target regions; plastic implant catheters; prostate; transient temperature profiles; tubular ultrasound transducers; ultrasound applicators; Acoustic transducers; Applicators; Coagulation; Computer simulation; In vivo; Medical treatment; Plastics; Temperature distribution; Ultrasonic imaging; Ultrasonic transducers;
fLanguage :
English
Journal_Title :
Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on
Publisher :
ieee
ISSN :
0885-3010
Type :
jour
DOI :
10.1109/58.796127
Filename :
796127
Link To Document :
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