1. An X-ray CT apparatus comprising: an X-ray detector including a plurality of X-ray detection arrays, each X-ray detection array including a plurality of X-ray detection elements arranged in a matrix, the matrix having a plurality of columns of X-ray detection elements arranged in a channel direction, the channel direction being substantially orthogonal to a body axial direction, and a plurality of rows of X-ray detection elements arranged in a slice direction which is substantially parallel to the body axial direction; an amplifier unit having a plurality of amplifiers; a first connection unit connecting the plurality of X-ray detection elements and the amplifier unit; an AD converter unit having a plurality of AD converters; and a second connection unit connecting the amplifier unit and the AD converter unit, wherein each of the plurality of amplifiers is connected to a different group of X-ray detection elements from among the plurality of X-ray detection elements within one of the plurality of X-ray detection arrays, and none of the X-ray elements within any of the groups of X-ray detection elements connected to a single amplifier is directly adjacent to another X-ray detection element within the same group in either the channel direction or the slice direction in the matrix of the X-ray detection array.