1. A method for determining a target point within a human body by means of tomographic cut images from a tomographic scanner comprising the steps of: (a) placing a localizer in a fixed position relative to the body and with at least a portion of said localizer being adjacent to the skin of the body such that a tomographic scan cut through said localizer will give a first image point location on the scan image which determines a first physical point on the patient's skin adjacent to said localizer; (b) taking a first tomographic cut through the body and through said localizer from which said first physical point on the skin can be determined and from which a second image point on the skin can be determined on the image of said first tomographic cut, whereby the coordinate differences between said first image point and said second image point enable the unique position of the associated second physical point on the patient's skin to be determined; (c) taking a second tomographic cut through the body with a known displacement distance from said first tomographic cut from which a target image point can be identified and from which the coordinate position of the associated physical target point in the body can be determined relative to said second physical point seen in said first tomographic cut; and, (d) calculating a trajectory in space relative to the planes of the tomographic cuts which passes through said second physical point on the skin and through said physical target point and calculating the distance along said trajectory between said physical point and said physical target point.