With recent advancements of technology, radiofrequency ablation has become one of the most used techniques to treat liver tumors. But radiologists still have to face the difficulty of planning their treatment while only relying on 2D slices acquired from CT-scan. We present a tool called RF-Sim, being part of a complete 3D reconstruction and visualization project, and including both a realistic radiofrequency ablation simulator for training and rehearsal, and an automatic treatment planner taking into account tumor's environment. They help radiologists to have a better visualization of patients' anatomic structures and pathologies, and allow them to easily find an adequate treatment. They run on a common laptop and can be used in the operating room.