An IGRT apparatus includes a medical imaging device integrated with a linear accelerator, the linear accelerator is configured for emitting a radiation beam, which is shaped by a beam shaper, and a gantry. The position of the beam shaper is adjustable between a first position and a second position; the first position is a treatment position and the second position is a non-treatment position and the first position is within the gantry and the second position is removed from the gantry.