| Beam localization in HIFU temperature measurements using thermocouples, with application to cooling by large blood vessels. | |
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MedLine Citation:
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PMID: 20817250 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Experimental studies of thermal effects in high-intensity focused ultrasound (HIFU) procedures are often performed with the aid of fine wire thermocouples positioned within tissue phantoms. Thermocouple measurements are subject to several types of error which must be accounted for before reliable inferences can be made on the basis of the measurements. Thermocouple artifact due to viscous heating is one source of error. A second is the uncertainty regarding the position of the beam relative to the target location or the thermocouple junction, due to the error in positioning the beam at the junction. This paper presents a method for determining the location of the beam relative to a fixed pair of thermocouples. The localization technique reduces the uncertainty introduced by positioning errors associated with very narrow HIFU beams. The technique is presented in the context of an investigation into the effect of blood flow through large vessels on the efficacy of HIFU procedures targeted near the vessel. Application of the beam localization method allowed conclusions regarding the effects of blood flow to be drawn from previously inconclusive (because of localization uncertainties) data. Comparison of the position-adjusted transient temperature profiles for flow rates of 0 and 400ml/min showed that blood flow can reduce temperature elevations by more than 10%, when the HIFU focus is within a 2mm distance from the vessel wall. At acoustic power levels of 17.3 and 24.8W there is a 20- to 70-fold decrease in thermal dose due to the convective cooling effect of blood flow, implying a shrinkage in lesion size. The beam-localization technique also revealed the level of thermocouple artifact as a function of sonication time, providing investigators with an indication of the quality of thermocouple data for a given exposure time. The maximum artifact was found to be double the measured temperature rise, during initial few seconds of sonication. |
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Authors:
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Subhashish Dasgupta; Rupak K Banerjee; Prasanna Hariharan; Matthew R Myers |
Publication Detail:
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Type: Journal Article; Research Support, U.S. Gov't, Non-P.H.S. Date: 2010-08-13 |
Journal Detail:
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Title: Ultrasonics Volume: 51 ISSN: 1874-9968 ISO Abbreviation: Ultrasonics Publication Date: 2011 Feb |
Date Detail:
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Created Date: 2010-11-24 Completed Date: 2011-01-11 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0050452 Medline TA: Ultrasonics Country: Netherlands |
Other Details:
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Languages: eng Pagination: 171-80 Citation Subset: IM |
Copyright Information:
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Copyright © 2010 Elsevier B.V. All rights reserved. |
Affiliation:
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Mechanical Engineering Department, University of Cincinnati, Cincinnati, OH 45220, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Algorithms Equipment Design Gels Humans Models, Theoretical Phantoms, Imaging Regional Blood Flow Reproducibility of Results Temperature Transducers Ultrasonic Therapy / adverse effects, methods* |
| Chemical | |
Reg. No./Substance:
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0/Gels |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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