The invention relates to a temperature distribution determination apparatus for determining a temperature distribution within an object (20), while an energy application element (2) applies energy to the object, especially while an ablation procedure for ablating a tumor within an organ is performed. A time-dependent first ultrasound signal is generated for an ultrasound measurement region within the object and a temperature distribution within the object is determined based on the generated time-dependent first ultrasound signal and based on a position of the energy application element (2) relative to the ultrasound measurement region tracked over time. This can ensure that always the correct position of the energy application element, which may be regarded as being a heat source, is considered, even if the energy application element moves, for instance, due to a movement of the object. This can lead to a more accurate determination of the temperature distribution.
