Interventional Neuroradiology replaces surgery. This technology requires various exposition to X rays : number of X rays photographs, radioscopy, distance between patient and detector, speed of acquisition of X-rays photographs, high tension and intensity.

The manipulator must find the right balance between quality of photographs and dose delivered to the patient (optimization).

Children are particularly exposed to these risks of irradiation (sensitivity to X-rays and long life expectancy with risks. So, it is fundamental to optimize the dose delivered during the procedures.

The investigators propose to analyse a study comparing two protocols of optimization of doses. The investigators' hypothesis is that the protocol experimented in this trial allows less radiation of the children, compared to the usual protocol.

Inclusion Criteria:

• malformation or occlusion of a cerebral vessel requiring interventional Neuroradiology

Exclusion Criteria:

• opposition ot the parent(s) to the participation of their child in the trial and/or no social security.