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3 - Graphic display terminal 
It will be used to visualize the information from C.T. Scan- 
ner. At the present time we only display the skull and tumours outlines and 
the reference points allowing to replace each cross-sectional plane relati- 
vely to the stereotactic frame. 
A cursor is driven by the computer insuring real time chec- 
king in the C.T. slice being displayed. 
We hope to be able to use it for 3-D graphic display later 
on. : 
4 - Automatically-controlled tool-holder 
Connected to the computer, it will be placed on the stereo- 
tactic frame during the surgical intervention. It will allow to position the 
instruments of the surgeon in an half-automatic way (puncture needles, ther- 
mocouple needles, electrodes) according to previously defined trajectories 
in order to reach the target without causing any damage to surrounding ves- 
sels (which could be catastrophic). 
IV - CONCLUSION 
  
Carried out as described, the C.T. Scanner, stereotactic and 
stereoscopic information analysis system answers our purpose : how to define 
a target in cerebral 3-D space, how to define a trajectory leading to it 
without injuring dense vessels. The real time possibilities of our system, 
its great accuracy should make it very helpful for the surgeon (the system 
should be set up in our department at the end of 1982). 
ACKNOWLEDGEMENTS 
  
This work was supported by D.C.R.S.T (contract n? 81M1052) and ANVAR (con- 
tract n° A801004 3E/0460)