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The performance of a reduced-order adaptive controller when used in multi-antenna hyperthermia treatments with nonlinear temperature-dependent perfusion.

Publication ,  Journal Article
Cheng, K-S; Yuan, Y; Li, Z; Stauffer, PR; Maccarini, P; Joines, WT; Dewhirst, MW; Das, SK
Published in: Phys Med Biol
April 7, 2009

In large multi-antenna systems, adaptive controllers can aid in steering the heat focus toward the tumor. However, the large number of sources can greatly increase the steering time. Additionally, controller performance can be degraded due to changes in tissue perfusion which vary non-linearly with temperature, as well as with time and spatial position. The current work investigates whether a reduced-order controller with the assumption of piecewise constant perfusion is robust to temperature-dependent perfusion and achieves steering in a shorter time than required by a full-order controller. The reduced-order controller assumes that the optimal heating setting lies in a subspace spanned by the best heating vectors (virtual sources) of an initial, approximate, patient model. An initial, approximate, reduced-order model is iteratively updated by the controller, using feedback thermal images, until convergence of the heat focus to the tumor. Numerical tests were conducted in a patient model with a right lower leg sarcoma, heated in a 10-antenna cylindrical mini-annual phased array applicator operating at 150 MHz. A half-Gaussian model was used to simulate temperature-dependent perfusion. Simulated magnetic resonance temperature images were used as feedback at each iteration step. Robustness was validated for the controller, starting from four approximate initial models: (1) a 'standard' constant perfusion lower leg model ('standard' implies a model that exactly models the patient with the exception that perfusion is considered constant, i.e., not temperature dependent), (2) a model with electrical and thermal tissue properties varied from 50% higher to 50% lower than the standard model, (3) a simplified constant perfusion pure-muscle lower leg model with +/-50% deviated properties and (4) a standard model with the tumor position in the leg shifted by 1.5 cm. Convergence to the desired focus of heating in the tumor was achieved for all four simulated models. The controller accomplished satisfactory therapeutic outcomes: approximately 80% of the tumor was heated to temperatures 43 degrees C and approximately 93% was maintained at temperatures <41 degrees C. Compared to the controller without model reduction, a approximately 9-25 fold reduction in convergence time was accomplished using approximately 2-3 orthonormal virtual sources. In the situations tested, the controller was robust to the presence of temperature-dependent perfusion. The results of this work can help to lay the foundation for real-time thermal control of multi-antenna hyperthermia systems in clinical situations where perfusion can change rapidly with temperature.

Duke Scholars

Published In

Phys Med Biol

DOI

ISSN

0031-9155

Publication Date

April 7, 2009

Volume

54

Issue

7

Start / End Page

1979 / 1995

Location

England

Related Subject Headings

  • Uncertainty
  • Sarcoma
  • Nuclear Medicine & Medical Imaging
  • Nonlinear Dynamics
  • Neoplasms
  • Models, Biological
  • Leg
  • Hyperthermia, Induced
  • Humans
  • Hot Temperature
 

Citation

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Cheng, K.-S., Yuan, Y., Li, Z., Stauffer, P. R., Maccarini, P., Joines, W. T., … Das, S. K. (2009). The performance of a reduced-order adaptive controller when used in multi-antenna hyperthermia treatments with nonlinear temperature-dependent perfusion. Phys Med Biol, 54(7), 1979–1995. https://doi.org/10.1088/0031-9155/54/7/008
Cheng, Kung-Shan, Yu Yuan, Zhen Li, Paul R. Stauffer, Paolo Maccarini, William T. Joines, Mark W. Dewhirst, and Shiva K. Das. “The performance of a reduced-order adaptive controller when used in multi-antenna hyperthermia treatments with nonlinear temperature-dependent perfusion.Phys Med Biol 54, no. 7 (April 7, 2009): 1979–95. https://doi.org/10.1088/0031-9155/54/7/008.
Cheng K-S, Yuan Y, Li Z, Stauffer PR, Maccarini P, Joines WT, et al. The performance of a reduced-order adaptive controller when used in multi-antenna hyperthermia treatments with nonlinear temperature-dependent perfusion. Phys Med Biol. 2009 Apr 7;54(7):1979–95.
Cheng, Kung-Shan, et al. “The performance of a reduced-order adaptive controller when used in multi-antenna hyperthermia treatments with nonlinear temperature-dependent perfusion.Phys Med Biol, vol. 54, no. 7, Apr. 2009, pp. 1979–95. Pubmed, doi:10.1088/0031-9155/54/7/008.
Cheng K-S, Yuan Y, Li Z, Stauffer PR, Maccarini P, Joines WT, Dewhirst MW, Das SK. The performance of a reduced-order adaptive controller when used in multi-antenna hyperthermia treatments with nonlinear temperature-dependent perfusion. Phys Med Biol. 2009 Apr 7;54(7):1979–1995.
Journal cover image

Published In

Phys Med Biol

DOI

ISSN

0031-9155

Publication Date

April 7, 2009

Volume

54

Issue

7

Start / End Page

1979 / 1995

Location

England

Related Subject Headings

  • Uncertainty
  • Sarcoma
  • Nuclear Medicine & Medical Imaging
  • Nonlinear Dynamics
  • Neoplasms
  • Models, Biological
  • Leg
  • Hyperthermia, Induced
  • Humans
  • Hot Temperature