Teixeira, C. A.Pereira, W. C. A.Ruano, AntonioRuano, M. Graça2013-02-072013-02-072007Teixeira, C. A.; Pereira, W. C. A.; Ruano, A. E.; Ruano, M. Graca. NARX structures for non-invasive temperature estimation in non-homogeneous media, Trabalho apresentado em 2007 IEEE International Symposium on Intelligent Signal Processing, In Proceedings of the 2007 IEEE International Symposium on Intelligent Signal Processing, Alcala de Henares, Spain, 2007.978-1-4244-0829-0AUT: ARU00698; MRU00118;http://hdl.handle.net/10400.1/2255The safe and effective application of thermal therapies are limited by the existence of precise non-invasive temperature es-timators. Such estimators would enable a correct power deposition on the region of interest by means of a correct instrumentation control. In multi-layered media, the temperature should be estimated at each layer and especially at the interfaces, where significant temperature changes should occur during therapy. In this work, a non-linear autoregressive structure with exogenous inputs (NARX) was applied to non-invasively estimate temperature in a multi-layered (non-homogeneous) medium, while submitted to physiotherapeutic ultrasound. The NARX structure is composed by a static feed-forward radial basis functions neural network (RBFNN), with external dynamics induced by its inputs. TheNARX structure parameters were optimized by means of a multi- objective genetic algorithm. The best attained models reached a maximum absolute error inferior to 0.5 °C (proposed threshold in hyperthermia/diathermia) at both the interface and inner layer points, at four radiation intensities. These models present also a small computational complexity as desired for real-time applications. To the best of ours knowledge this is the first non-invasive estimation approach in multi-layered media using ultrasound for both heating and estimation.engNARX structuresRadial basis functions neural networksMulti-objective genetic algorithmsNon-invasive temperature estimationTherapeutic ultrasoundconference object2013-01-26http://dx.doi.org/10.1109/WISP.2007.4447544