Estimation of three-dimensional temperature fields from a limited number of transient temperature measurements during hyperthermia.

Persistent Link:
http://hdl.handle.net/10150/184424
Title:
Estimation of three-dimensional temperature fields from a limited number of transient temperature measurements during hyperthermia.
Author:
Clegg, Scott Tom.
Issue Date:
1988
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
In this dissertation, a new reconstruction algorithm to estimate the complete temperature field during hyperthermia is developed which relies upon a limited amount of transient measured temperature data. The predictive capabilities of this new algorithm are then systematically studied; first using one-dimensional simulated treatments, then using three-dimensional simulated treatments, and finally applying it to hyperthermia treatments of normal canine thighs. It was found that this new algorithm predicts the complete temperature fields more accurately and robustly than the steady-state approach. In particular, it can better predict the complete temperature fields in situations where the number of unknown blood perfusion parameters are greater than the number of available temperature sensors. It was also found that the steady-state temperature field could be estimated to within 1°C if there was no measurement noise, no model mismatch, and as few as three measurement locations for seven perfusion zones. The addition of measurement noise degraded the performance of this estimation algorithm especially when the number of measurement locations was small. It was found that use of Tikhonov regularization of order zero significantly improved the performance of the algorithm and that there was an optimal choice for the regularization parameter. For the animal experiments, normal canine thighs were instrumented with one-hundred twelve thermocouples and heated to steady-state using a 6 cm planar ultrasound transducer operating at 0.5 MHz: then the power was turned off and the transient cool down temperature data was stored for later use by the reconstruction algorithm. Only a subset of the one-hundred twelve measurements was used as input to the reconstruction algorithm. The remaining measurements were used to compare the results of the reconstruction algorithm with the true temperatures. The results showed that in general the predicted perfusion and reconstructed temperature field did not change significantly as sensors were removed. However, the error was quite large for some of the situations studied particularly when only twenty-seven piecewise constant regions of perfusion were used. Increasing the number of perfusion regions reduced this error suggesting that model mismatch had contributed significantly to the error.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Body temperature -- Measurement.; Thermotherapy -- Measurement.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Aerospace and Mechanical Engineering; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Roemer, R. B.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleEstimation of three-dimensional temperature fields from a limited number of transient temperature measurements during hyperthermia.en_US
dc.creatorClegg, Scott Tom.en_US
dc.contributor.authorClegg, Scott Tom.en_US
dc.date.issued1988en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractIn this dissertation, a new reconstruction algorithm to estimate the complete temperature field during hyperthermia is developed which relies upon a limited amount of transient measured temperature data. The predictive capabilities of this new algorithm are then systematically studied; first using one-dimensional simulated treatments, then using three-dimensional simulated treatments, and finally applying it to hyperthermia treatments of normal canine thighs. It was found that this new algorithm predicts the complete temperature fields more accurately and robustly than the steady-state approach. In particular, it can better predict the complete temperature fields in situations where the number of unknown blood perfusion parameters are greater than the number of available temperature sensors. It was also found that the steady-state temperature field could be estimated to within 1°C if there was no measurement noise, no model mismatch, and as few as three measurement locations for seven perfusion zones. The addition of measurement noise degraded the performance of this estimation algorithm especially when the number of measurement locations was small. It was found that use of Tikhonov regularization of order zero significantly improved the performance of the algorithm and that there was an optimal choice for the regularization parameter. For the animal experiments, normal canine thighs were instrumented with one-hundred twelve thermocouples and heated to steady-state using a 6 cm planar ultrasound transducer operating at 0.5 MHz: then the power was turned off and the transient cool down temperature data was stored for later use by the reconstruction algorithm. Only a subset of the one-hundred twelve measurements was used as input to the reconstruction algorithm. The remaining measurements were used to compare the results of the reconstruction algorithm with the true temperatures. The results showed that in general the predicted perfusion and reconstructed temperature field did not change significantly as sensors were removed. However, the error was quite large for some of the situations studied particularly when only twenty-seven piecewise constant regions of perfusion were used. Increasing the number of perfusion regions reduced this error suggesting that model mismatch had contributed significantly to the error.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectBody temperature -- Measurement.en_US
dc.subjectThermotherapy -- Measurement.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineAerospace and Mechanical Engineeringen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorRoemer, R. B.en_US
dc.contributor.committeememberVincent, T. J.en_US
dc.contributor.committeememberPearlstein, A. J.en_US
dc.identifier.proquest8816310en_US
dc.identifier.oclc701248581en_US
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