Abstract: The invention presents tools to improve a 3-D image aided biopsy or treatment procedure for prostate gland by providing additional functionality and additional visual cues on an output image of the prostate, which may be generated substantially in real-time. The tools include i) the identification of various parts of prostate to classify as per regular classification in pathological reports, ii) Computing and displaying the insertion depth of needle with respect to a selected target point during the procedure, iii) Computing and displaying the distance from needle tip to prostate surface following a procedure and, iv) Calibration for misalignment of a 2-D imaging transducer when used under tracked motion for a procedure.