In an arrangement for connecting a dental X-ray imaging sensor to a holder; the sensor (9) is a flat piece (11) having a planar radiation sensitive area, and at least one communication line (12) connected to said radiation sensitive area for data transfer; and the holder (8) is an elongated body having a first end provided with means for detachable connection of said sensor. The sensor has a peg (3) projecting from said flat piece. The peg is provided with a widened outer end and a neck between said outer end and said flat piece. Further, the neck has a configuration with a plurality of alternate larger diameters and smaller diameters. The holder has at its first end a fork (4) with a gap, which is adapted to fit onto said neck at least in two different positions. The interaction between the fork and the larger and smaller diameters of the neck prohibits unintended pivot of said sensor in respect to the holder.