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’ ?

Diagrammatic representation of the American standard cephalometric arrangement. By convention, the distance from the X-ray source to the subject's 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.