Abstract: An interactive system for a local intervention inside a region of a non-homogeneous structure, such as the skull of a patient, which is related to the frame of reference (R.sub.2) of an operation table, and which is connected to a reference structure comprising a plurality of base points. The system creates on a screen a representation of the non-homogeneous structure and of the reference structure connected thereto, provides the coordinates of the images of the base points in the first frame of reference (R.sub.1), allows the marking of the coordinates of the base points in R.sub.2, and allows the carrying out of the local intervention with an active member such as a trephining tool, a needle, or a radioactive or chemical implant. The systems also optimizes the transfer of reference frames between R.sub.1 and R.sub.2, from the coordinates of the base points in R.sub.2 and the images in R.sub.1 by reducing down to a minimum the deviations between the coordinates of images in R.sub.1 and the base points in R.

Abstract: An interactive system for a local intervention inside a region of a non-homogeneous structure, such as the skull of a patient, which is related to the frame of reference (R2) of an operation table, and which is connected to a reference structure comprising a plurality of base points. The system creates on a screen a representation of the non-homogeneous structure and of the reference structure connected thereto, provides the coordinates of the images of the base points in the first frame of reference (R1), allows the marking of the coordinates of the base points in R2, and allows the carrying out of the local intervention with an active member such as a trephining tool, a needle, or a radioactive or chemical implant. The systems also optimizes the transfer of reference frames between R1 and R2, from the coordinates of the base points in R2 and the images in R1 by reducing down to a minimum the deviations between the coordinates of images in R1 and the base points in R1 after transfer.