If your intent is to use the XRF to determine the presence or the concentration of lead and to report your findings based on the XRF results, then you must be licensed as a lead inspector or risk assessor. If the XRF is an x-ray tube based model it should be registered with the Missouri Department of Health and Senior Services Office of Radiation Control. You are required to have received training from the XRF manufacturer on safe and proper operation of the instrument.