An image sensor having a two-dimensional array of CMOS pixel sensors, a row decoder and a column decoder is disclosed. The two-dimensional array of CMOS pixel sensors is organized as a plurality of rows and columns that are addressed with the aid of row and column decoders. At least one of the column decoder or the row decoder is located between two of the rows or two of the columns, respectively. X-rays are converted to light that is detected by the image sensor by a layer of scintillation material that overlies the two-dimensional array. The internally located decoder or decoders facilitate sensors in which the two-dimensional array includes a rectangular array having a chamfered corner such that rows or columns that extend into the chamfered corner have lengths that are less than rows or columns, respectively, that do not extend into the corners.