Abstract: An x-ray detector assembly includes a first substrate and a second substrate. An array of photodetectors, which have coplanar contacts, are disposed on the top surface of the first substrate. The x-ray detector assembly further includes a plurality of x-ray scintillator elements arranged in an array. The photodetectors are aligned so as to match the array of x-ray scintillator elements. The second substrate is fused to the bottom surface of the first substrate. The second substrate provides on its distal side a planar connectivity pattern matched to electronics of a signal acquisition system. One or more through-hole connections traverse both substrates, and are configured to couple the contacts of the photodetectors from the top surface of the first substrate to the connectivity pattern on the distal side of the second substrate.