 Most radiation therapy is planned using the results of a 3D CT scan.A 3D scan largely presents a snapshot of the body at a particular point in time, however due to the time of the acquisition, in which the patient is likely to have moved in some way (even if only breathing), there will be an element of blurring or averaging in the 3D scan.When it comes to treatment planning, this motion can mean there is less accuracy in the positioning of treatment beams, and reduce the likelihood of a repeatable set-up on the linear accelerator when it comes to treatment.