The treatment intervention by Gamma Knife consists of 4 consecutive stages:

Installation of the stereotaxic frame  
Stereotaxic neurosurgery procedures are used to analyse lesions of the brain once they have been located with high precision.  To arrive at such a high precision, Gamma Knife radiosurgery requires the installation of a reference frame known as “stereotaxic frame” from which the lesion is located in 3 dimensions.
Brain imaging  
Brain imaging locates with precision the lesion to be treated in relation to the stereotaxic frame, so as to obtain the data needed to plan the treatment, i.e. send rays to the target determined by these coordinates.  Several types of imaging can be used during radiosurgical treatment by Gamma Knife, including magnetic resonance imaging (MRI), scanner, position emission tomography (PET scan) and/or angiography.  The choice of types of imagery is specific to each indication and each patient in particular.
Dosimetric planning  
This stage of the radiosurgery intervention is carried out on a computer using a specific programme for Gamma Knife (GammaPlan®). It consists of determining the optimal parameters of the treatment based on the stereotaxic images obtained previously.  Different simulations of the treatment are carried out and calculations of irradiation doses are made.  Different quality control checks are then carried out.
Radiosurgical irradiation  
The Gamma Knife machine is programmed with the data obtained from the dosimetric planning.  The patient lies on the Gamma Knife bed, and the stereotaxic frame is attached to the machine.  Once the position of the frame is verified, the treatment can proceed.  The duration of the irradiation depends on the different parameters of the dosimetric planning (e.g. number of lesions, complexity of the shape of the lesion(s), etc.).


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