Abstract: A radiation therapy system is disclosed. The radiation therapy system includes a gantry, a first radiation source, and a second radiation source. The gantry is configured to have a cavity extending in a direction along a rotation axis, and the cavity is configured to house a target object. The first radiation source is mounted on the gantry, and configured to emit a treatment beam to a treatment area of the target object. The second radiation source is mounted on the gantry, and configured to emit an imaging beam to an imaging area of the target object. The treatment area partially overlaps the imaging area. A rotation plane of the first radiation source and a rotation plane of the second radiation source are distributed in a direction along the rotation axis.