Methods and systems achieve tissue ablation, which is carried out by inserting a probe having an ablation electrode into a body of a living subject, and while the ablation electrode is in a non-contacting relationship to a target tissue, making a pre-contact determination of a phase of an electrical current passing between the ablation electrode and another electrode. The ablation electrode is placed in contact with the target tissue, and while the ablation electrode is in the contacting relationship, a dosage of energy is applied via the ablation electrode to the target tissue for ablation thereof. Iterative intra-operative determinations of the phase of the electrical current are made. When one of the intra-operative determinations satisfies a termination criterion, the energy application is terminated.
