Safe radiation distance?

I shadowed a pedo clinic. The xray button on the wall seems to close the tube head and room….. it looks about 5 feet. I want to ask or measure myself but i dont look weired or offended the dentist.. i did see a xray certificate thing by the wall in the xray room. Idk if that confirms anything. How would you advise to go about it. Other than that, i liked the office.