I don’t know anythink else technically. The orthopaedic doctor prescribed (asked) the Rx services only a full ,view ("two" or "3 views", or "panoramic" I don’t remember) of legs and at the end I could see the measures in millimeters both marked by horizontal lines in the Rx itself and in that very brief report about it (which included a table left/right leg for lower and upper segments separately). It was a relatively cheap exam. I didn't use  neither insurance nor NHS.
I don’t know the medical criteria to mark the lines that define the measurements made. I only remember I had to be both in ventral and dorsal positions.