According to the invention there is provided a radiation source for use in endovascular radiation treatment which comprises one or more and preferably at least two treating elements or seeds comprising a radiation emitting element and means for containment of said radiation emitting element which radiation source is characterized in that said seeds comprised in an elongated container having at least one deflection site. There is further provided an apparatus for endovascular radiation treatment comprising an elongated catheter, optionally a guide wire and the radiation source as defined above. According to another aspect there is provided a method for endovascular radiation treatment comprising the steps of directing an elongated catheter to the selected site to be treated, introducing a radiation source as defined above into the catheter at its proximal end portion, moving said radiation source to the distal end portion of the catheter preferably by use of a transfer wire, maintaining said radiation source at that distal end portion for a predetermined period of time and retracting said radiation source to the proximal end portion of the catheter preferably by use of a transfer wire.