Abstract: Systems and methods for providing access to a target site. Example systems can include a needle and a grid to guide the needle. One system includes a plate with an aperture, a member coupled to the plate and including a semispherical surface, and a hub slideably coupled to the plate by a guide. The system can also include a lock mechanism configured to lock the hub relative to the plate on the guide, and a needle coupled to the hub, the needle including a magnetically trackable sensor positioned in a tip of the needle. The semispherical surface of the member can be positioned against skin of a body and the hub slid relative to the plate along the guide to insert the needle through the aperture in the plate into the body until the tip reaches a target site. The hub can be locked by the lock mechanism when the tip of the needle reaches the target site, and an ablation agent is delivered to the target site through the needle, or a tissue sample is obtained.