Patent ID: 7317189

Claim:
An X-ray CT apparatus comprising: an X-ray generating unit configured to irradiate an X-ray to an object; and a radiation detector configured to detect the X-ray transmitted through the object; wherein the radiation detector includes: a plurality of detecting elements put in two-dimensional positions, and separated into a plurality of readout blocks; a readout circuit configured to read out electric signals from the detecting elements in the respective readout blocks; a switch circuit configured to switch the electric signals read out to the readout circuit from the detecting elements at the readout blocks; and a switch control circuit configured to control the switch circuit so as to read out electric signals with time-sharing from corresponding detecting elements in a common readout block of the readout blocks to the readout circuit and to read out corresponding electric signals in parallel from at least two of the detecting elements to the readout circuit, the at least two of the detecting elements being in different readout blocks from each other, the radiation detector being configured to make a readout order of the electric signals with time-sharing variable in the respective readout blocks by controlling the switch circuit.