Abstract: In accordance with an embodiment, an apparatus determines the location of landmarks inside a patient. The apparatus includes imaging units containing two-dimensional imaging arrays capable of emitting and receiving signals to obtain three-dimensional images. The imaging units are attached to the patient's body and their location is established with a tracking system and used to compute the position of landmarks from the images. The images are adjusted relative to the imaging units such that the landmarks remain inside the images during motion of landmarks or imaging unit. The apparatus also includes a control and computing device to process the image data and to adjust the imaging arrays accordingly. In accordance with one embodiment, sources of treatment are directed towards a target structure in the patient's body.