ACCURATE USE OF CT. SCANNER, STEREOTAXIS AND PHOTOGRAMMETRY
FOR DIAGNOSIS AND TREATMENT OF CEREBRAL LESIONS (TUMOURS )
* * *
B. GIBAUD, J-M SCARABIN*, B. LORIG, C.CRUETTE
(Service de Neurochirurgie, Prof. PECKER, CHU Rennes
1l, rue H. Le Guillou 35000 - RENNES)
Summary :
The authors explain the present state of their research on an
accurate system for analysis and combination of three-dimensional informa-
tion from C.T.Scanner, stereotaxis and stereoscopy.
The basic problem is the transfer of co-ordinates between these
different investigation techniques. The theoritically simple geometrical
problem has proven quite difficult in practice. A careful study of a refe-
rence device is needed. A second important point is the organization of the
system which must not ignore the technical, medical and economical con-
texts. This system consists in the computing unit of an analytical stereo-
plotter, connected to peripheral units that shall be further detailed.
Index terms : Computed tomography, stereotaxis, photogrammetry, head fixa-
tion system.
I - INTRODUCTION
A)
= The diagnostic and therapeutic approach to cerebral lesions (es-
pecially tumours) requires their perfect localization and a good knowledge
of their vascular environment.
Roughly speaking the problem may be exposed as follows : where is
the target in 3-D space ? How is it possible to reach it safely ? (espe-
cially regarding vessels).
To solve this problem we need a 3-D analysis of radiological in-
formation from the brain. At the present time we can get this information
in three different ways : CT slices, stereotactic radiograms, pairs of ste-
reoscopic angiograms.
] - CT Scanner
It allows to reconstruct and visualize images of the densities of
the cerebral tissues in successive planes of axial cross-sections (or fron-
tal or lateral slices after reconstruction). Yet, in spite of the qualities
and the informative value of these images, the localization of the lesions
in 3-D space is not accurate as a result of the lack of a reliable head fi-
xation system.
Furthermore, this kind of examination cannot detect small intra-
cranial vessels and leaves great uncertainty about the histological nature
of the tumours.
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