<prompt> A 12 year old male patient wants to undergo orthodontic treatment as he feels his upper incisors are too prominent. He is advised a pre-treatment lateral cephalogram. What is the value of distance A ?4 feet50 inches6 feet60 inches  <response>: Diagrammatic representation of the American standard cephalometric arrangement. By convention, the distance from the X-ray source to the subjects midsagittal plane is 5 feet 60 inches. The distance from the midsagittal plane to the cassette can vary in many machines, but must be the same for each patient every time. 