The analog positioner plays an important role in the design of the entire radiation therapy plan:

　　1) Target area and location of important organs

　　2) Determine the range of motion of the target area (or endangered organ)

　　3) Confirmation of treatment plan

　　4) Sketch the field and position, position reference mark

　　5) Shooting field positioning film and confirmation film

　　6) Check the shape and position of the field stop