(Photo reprinted courtesy of LANDAUER ©2018)
Were you aware that over 600 individuals in the Washington, DC/Baltimore area receive a personnel dosimeter in order to measure the amount of radiation exposure they receive while working at NIH? These are individuals who directly handle radioactive material in a research lab or clinical setting, or who operate some type of x-ray machine for research or patient care purposes.
Radiation Safety is required by law to evaluate who needs a personnel dosimeter. The regulations state that anyone with exposure potential greater than 10% of the regulatory limit must be assigned a personnel dosimeter so that their radiation dose can be measured and tracked. Most researchers at NIH do not require a dosimeter to be assigned to them, because the amounts of radioactive material being handled are very low, or the radiation energies of the radioactive material are very low. Handling beta emitters, like H-3, S-35, C-14, and P-32, and low-energy gamma emitters like I-125, will hardly ever trigger the need for a personnel dosimeter, because the radiation worker won't get more than 10% of the allowable dose limit.
Since the allowable dose limit (to the whole body) is 5000 millirem per year, that means that most radiation workers won't even get more than 500 millirem from their work at NIH – that's less than the radiation dose an average person in the U.S. gets in a year from their personal medical procedures and background radiation.
The Division of Radiation Safety (DRS) in Bethesda, MD uses an online "Dosimeter Evaluation Form," available on the DRS website at https://drs.ors.od.nih.gov, in order to estimate an individual's need for a dosimeter. This form projects the need based on the intended type(s) of radioactive material, the quantities, and handling time (frequency of use).
Since this information will change over time, and since many workers have not had their dosimetry needs re-evaluated in many years, DRS is embarking on an initiative to revisit the dosimeter evaluation starting with the "oldest" records first. This will help better document the current usage and ensure we don't overlook monitoring those who might not have needed a dosimeter in the past but who need one now. Those who are targeted for this re-evaluation will receive direct communication from DRS in the coming weeks.
This also serves as a reminder that if you are issued personnel dosimetry, it is because DRS believes you have a dose potential to receive 10% (or more) of the allowable radiation dose limit. Please be certain to exchange your dosimeter(s) promptly when a new one is issued, so your radiation dose is measured in a timely manner. DRS cannot know your radiation dose until the dosimeter is analyzed for the stored information it contains.
DRS looks forward to continued service to you, and welcomes any questions or concerns you may have related to your radiation dose potential from the use of radiation and radioactive materials in our workplace. Call Radiation Safety at 301-496-5774.