Tomi Huttunen

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In this paper, a method for the determination of spatially varying thermal conductivity and perfusion coefficients of tissue is proposed. The temperature evolution in tissue is modelled with the Pennes bioheat equation. The main motivation here is a model-based optimal control for ultrasound surgery, in which the tissue properties are needed when the(More)
In this paper the previously published optimization algorithm for thermal dose optimization is tested with numerical simulations. The simulations concern the thermal dose optimization in ultrasound surgery of the breast. The optimization algorithm is extended by setting the inequality constraint approximations to temperature in healthy tissue as well as in(More)
One of the problems in ultrasound surgery is the long treatment times when large tumour volumes are sonicated. Large tumours are usually treated by scanning the tumour volume using a sequence of individual focus points. During the scanning, it is possible that surrounding healthy tissue suffers from undesired temperature rise. The selection of the scanning(More)
We investigate the ultra weak variational formulation for simulating time-harmonic Maxwell problems. This study has two main goals. First, we introduce a novel derivation of the UWVF method which shows that the UWVF is an unusual version of the standard upwind discontinuous Galerkin (DG) method with a special choice of basis functions. Second, we discuss(More)
In this paper we investigate the feasibility of using the ultra weak variational formulation (UWVF) to solve the timeharmonic 3D elastic wave propagation problem. The UWVF is a non-polynomial volume based method that uses plane waves as basis functions which reduces the computational burden. More general, the UWVF is a special form of the discontinuous(More)
In this paper we extend the standard Ultra Weak Variational Formulation (UWVF) of Maxwell’s equations in an isotropic medium to the case of an anisotropic medium. We verify that the underlying theoretical framework carries over to anisotropic media (however error estimates are not yet available) and completely describe the new scheme. We then consider TM(More)
Needle and spot-poled membrane hydrophones using polyvinylidene fluoride (PVDF) sensors are widely used for characterization of biomedical ultrasound fields. It is known that, in measurements of continuous-wave (CW) fields, standing waves may be generated between the transducer and the hydrophone, distorting the field and possibly alternating the signal of(More)
In this paper, a model-based optimization method is derived to control the thermal dose in biological tissues for ultrasound surgery. The optimization method uses the bioheat equation as a system model and quadratic cost criteria for the desired thermal dose. Time-harmonic quasi-stationary ultrasound fields are used as the heat source. In this method the(More)