A radiation system may include a treatment assembly including a first radiation source, a second radiation source, and a first radiation detector. The first radiation source may be configured to deliver a treatment beam covering a treatment region of the radiation system, and the treatment region may be located in a bore of the radiation system. The second radiation source may be configured to deliver a first imaging beam covering a first imaging region of the radiation system, and may be mounted rotatably on a first side of the treatment assembly. The first radiation detector may be configured to detect at least a portion of the first imaging beam, and may be mounted rotatably on a second side of the treatment assembly. The treatment assembly, the second radiation source, and the first radiation detector may be positioned such that the treatment region is addressable for the radiation system.