A system for performing an interventional medical procedure is disclosed. The system includes a treatment device having a treatment portion, a localization system, and a means for defining a boundary about the treatment portion relative to location data point. The system may further be configured to provide a response when a portion of the treatment device enter or leaves a defined boundary, region, or range. Methods for performing interventional medical procedures that, among other things, reduce or prevent collateral damage to non-target regions are also disclosed.