A radiation tomography system is provided. The radiation tomography system includes a radiation source configured to rotate around a subject and apply radiation to the subject, a plurality of radiation detecting elements disposed opposite the radiation source, a plurality of collimator plates partitioning the radiation detecting elements in a channel direction, the collimator plates erected such that plate surfaces of each of the plurality of collimator plates extend along a direction of radiation from the radiation source, and an aperture-width changing unit configured to change a width of each aperture formed by the plurality of collimator plates by moving a plurality of radiation absorbing members along respective end sides of the collimator plates close to the radiation source, the plurality of radiation absorbing members moveable between a first position at which the end sides are covered and a second position at which the end sides are exposed.
