X-ray therapy EPI artifact reduction and control of imaging is provided. The support walls 9 are abutted at their lower ends against the uppermost wiring board 41, enabling the connector to be supported by both the support walls 9 and the fixing parts 8. Attachment of the folded foil to the brush base portion involves use of barrier tape andor adhesive on the folded side of the foil layers and soldering of one layer edge to the base portion which is received within a holder to position the folded foil in brushing contact along the other layer edges with a running surface under a spring bias pressure. Generic attack signatures describe relatively broad classes of intrusions.