Percutaneous radiofrequency ablation is one of the most promising alternatives to open surgery for the treatment of liver
cancer. This operation is a minimally invasive procedure that consists in inserting a needle in targeted tissues that are
destroyed by heat. The success of such an operation mainly depends on the accuracy of the needle insertion, making it
possible to destroy the whole tumor, while avoiding damages on other organs and minimizing risks of a local recurrence.
We are developing a software that applies planning rules on patient-specific 3D reconstructions, in order to suggest relevant
options for the choice of a path to the tumor, and that displays various information allowing to adjust the final choice. In this
context we propose a method to compute automatically, quickly, and accurately, the possible insertion areas on the skin.
Within these areas, an insertion of the probe targeting the tumor respects the numerous strong (boolean) constraints required
for a radiofrequency ablation. Besides, these insertion zones define the research domain of the optimization process, taking
into account soft constraints to refine the solutions. They are also displayed on the skin of the virtual patient to inform the
physician about the different possibilities specific to each case, allowing him at the end of the automatic process, to modify
interactively the proposed strategy, with a real-time update of the related information. We discuss in this paper about the
importance of a precise delineation of these areas.