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High-intensity focused ultrasound therapy: an overview for radiologists.

Kim YS, Rhim H, Choi MJ, Lim HK, Choi D - Korean J Radiol (2008 Jul-Aug)

Bottom Line: This completely non-invasive technology has great potential for tumor ablation as well as hemostasis, thrombolysis and targeted drug/gene delivery.However, the application of this technology still has many drawbacks.It is expected that current obstacles to implementation will be resolved in the near future.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.

ABSTRACT
High-intensity focused ultrasound therapy is a novel, emerging, therapeutic modality that uses ultrasound waves, propagated through tissue media, as carriers of energy. This completely non-invasive technology has great potential for tumor ablation as well as hemostasis, thrombolysis and targeted drug/gene delivery. However, the application of this technology still has many drawbacks. It is expected that current obstacles to implementation will be resolved in the near future. In this review, we provide an overview of high-intensity focused ultrasound therapy from the basic physics to recent clinical studies with an interventional radiologist's perspective for the purpose of improving the general understanding of this cutting-edge technology as well as speculating on future developments.

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Related in: MedlinePlus

Various methods of focusing US waves: A. Spherically-curved transducer, B. Flat transducer with interchangeable lens, C. Phased-array transducer causing only steering, and D. Phased-array transducer causing steering and focusing at same time.
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Figure 4: Various methods of focusing US waves: A. Spherically-curved transducer, B. Flat transducer with interchangeable lens, C. Phased-array transducer causing only steering, and D. Phased-array transducer causing steering and focusing at same time.

Mentions: The various methods of focusing US waves have been another important issue. The simplest and cheapest (often most accurate) method may be a shelf-focusing, for instance, a spherically curved US source (transducer). An US transducer constructed according to this method, has a beam focus fixed at the position determined from the geometrical specifications of the transducer. To compensate for its lack of versatility, a flat US transducer with an interchangeable acoustic lens system was devised. The acoustic lens enables variation of focusing properties such as focal length and focal geometry. However, a drawback of the lens system is that US waves undergo sonic attenuation due to absorption by the lens (14). Recently, a phased-array US transducer technique was adopted for HIFU therapy. By sending temporally different sets of electronic signals to each specific transducer component, this technique enables beam-steering and focusing, which can move a focal spot in virtually any direction within physically allowed ranges. This system is not only more versatile than other systems but also highly efficient without any sonic attenuation (15) (Fig. 4).


High-intensity focused ultrasound therapy: an overview for radiologists.

Kim YS, Rhim H, Choi MJ, Lim HK, Choi D - Korean J Radiol (2008 Jul-Aug)

Various methods of focusing US waves: A. Spherically-curved transducer, B. Flat transducer with interchangeable lens, C. Phased-array transducer causing only steering, and D. Phased-array transducer causing steering and focusing at same time.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2627265&req=5

Figure 4: Various methods of focusing US waves: A. Spherically-curved transducer, B. Flat transducer with interchangeable lens, C. Phased-array transducer causing only steering, and D. Phased-array transducer causing steering and focusing at same time.
Mentions: The various methods of focusing US waves have been another important issue. The simplest and cheapest (often most accurate) method may be a shelf-focusing, for instance, a spherically curved US source (transducer). An US transducer constructed according to this method, has a beam focus fixed at the position determined from the geometrical specifications of the transducer. To compensate for its lack of versatility, a flat US transducer with an interchangeable acoustic lens system was devised. The acoustic lens enables variation of focusing properties such as focal length and focal geometry. However, a drawback of the lens system is that US waves undergo sonic attenuation due to absorption by the lens (14). Recently, a phased-array US transducer technique was adopted for HIFU therapy. By sending temporally different sets of electronic signals to each specific transducer component, this technique enables beam-steering and focusing, which can move a focal spot in virtually any direction within physically allowed ranges. This system is not only more versatile than other systems but also highly efficient without any sonic attenuation (15) (Fig. 4).

Bottom Line: This completely non-invasive technology has great potential for tumor ablation as well as hemostasis, thrombolysis and targeted drug/gene delivery.However, the application of this technology still has many drawbacks.It is expected that current obstacles to implementation will be resolved in the near future.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.

ABSTRACT
High-intensity focused ultrasound therapy is a novel, emerging, therapeutic modality that uses ultrasound waves, propagated through tissue media, as carriers of energy. This completely non-invasive technology has great potential for tumor ablation as well as hemostasis, thrombolysis and targeted drug/gene delivery. However, the application of this technology still has many drawbacks. It is expected that current obstacles to implementation will be resolved in the near future. In this review, we provide an overview of high-intensity focused ultrasound therapy from the basic physics to recent clinical studies with an interventional radiologist's perspective for the purpose of improving the general understanding of this cutting-edge technology as well as speculating on future developments.

Show MeSH
Related in: MedlinePlus