A radiation imaging system (S, Fig. 1) comprises radiation imaging apparatuses (imagers) D1,D2 each comprising a radiation detecting panel (detector) 2, including detector pixels arrayed in a two-dimensional matrix, and an enclosure 1,6 enveloping the detector. The imagers D1,D2 are arrayed so that a part of each of the imagers spatially overlaps another. At least one of the imagers has an enclosure with a higher transmittance, i.e. lower attenuation, in the overlapping region than in a different region, e.g. due to different thicknesses of the enclosure in different regions. The enclosure may comprise two members one of which 6 having a higher rigidity and lower transmittance than the other 1. Carbon fibre reinforced polymers (CFRP), aluminium, or magnesium may be used for the enclosure. The enclosure may comprise a slanted and/or rounded face (see e.g. Fig. 3A) due to which the enclosure itself may become thinner towards an outer edge.
