Radiation residue will be there for a longer period of time after the last use,
but as long as the amount of radiation is small it is not a big deal.
The human body will not get radiation sickness in less than 10 hours in a 50-radiant area, and in less than 2 hours in a 200-radiant area!
The old X-ray machine residue is very large, 74 years my father (three defense force instructor) by a hospital commissioned to test the hospital's radiation contamination. Since it was a military instrument the maximum measurement was at 50 Lun. Once the building was gathered