23 February 2011 Fast optimization and planning of clinical interstitial ultrasound hyperthermia using superposition and surrogate models of temperature distributions
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Abstract
Conformable hyperthermia can be administered in the prostate, immediately following radiation, using multiple (2-6) directional ultrasound transducer arrays through previously implanted HDR brachytherapy catheters. These ultrasound devices provided controlled heating in angle and length. To plan a hyperthermia treatment, the patient anatomy and catheter geometry were reconstructed from CT images. Transducer powers were estimated to maximize the heated tumor volume, while sparing the surrounding organs. Fast computation of temperature elevations was performed by approximating the temperature rise induced at a point as the superposition of temperature increases resulting from individual transducers. Steady state temperature increases due to individual transducer elements (90 - 360° sector angles, 0 - 2 W) were precalculated and stored in a lookup table. Instead of using computationally expensive 3D finite element methods (FEM), temperature profiles were generated through interpolation and superposition of the precomputed data. These approximate models were included in a gradient search optimization, reducing the treatment planning time by a factor greater than 4.0 compared to the FE model. For 10 patient cases with dominant intraprostatic lesions, the optimized treatment plans were furnished in 10 - 35 minutes and yielded T90 > 40.0°C in most cases. The corresponding T90 values obtained through rigorous FE modeling were within 0.5 °C.
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Vasant A. Salgaonkar, Vasant A. Salgaonkar, Punit Prakash, Punit Prakash, Chris J. Diederich, Chris J. Diederich, } "Fast optimization and planning of clinical interstitial ultrasound hyperthermia using superposition and surrogate models of temperature distributions", Proc. SPIE 7901, Energy-based Treatment of Tissue and Assessment VI, 79010P (23 February 2011); doi: 10.1117/12.876410; https://doi.org/10.1117/12.876410
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