An apparatus and a method for performing a medical procedure is disclosed. In an embodiment for an apparatus of the present invention, the apparatus includes a positioning system and a resection device disposed within the positioning system. The positioning system includes an imaging device, a video processor coupled to the imaging device, a computer coupled to the video processor, and a video display coupled to the computer. In an embodiment for a method of practicing the present invention, the method includes the steps of creating an image of a lesion within a patient's body on an imaging device. Data representative of the lesion image is processed by a video processor. Tissue margins around the lesion are defined by a processor based on the processed data representative of the lesion image and a resection device is operated during a resection procedure within the patient's body based upon the defined tissue margins.