Do you need a dosimeter? It's a question that many radiation workers have asked themselves. The answer is that it depends on the type of radiation you are exposed to and the amount of radiation you are likely to receive. Dosimeters are required to be issued if a person is likely to receive more than 10 percent of the maximum allowable dose. Ring dosimeters are emitted to monitor radiation exposure of the hands.
Who needs a dosimeter? Generally, radiation workers who operate x-ray machines, fluoroscopy units, certain unsealed and sealed radioisotopes, or who are exposed to other sources of high-energy gamma or beta radiation must use one or more dosimeters. Radiation safety regulations state that anyone with an 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 NIH researchers do not require a dosimeter to be assigned to them, because the quantities of radioactive material being handled are very low or the radiation energies of the radioactive material are very low. Handling beta emitters, such as H-3, S-35, C-14 and P-32, and low-energy gamma emitters such as the I-125, will almost never trigger the need for a personnel dosimeter, because the radiation worker will not receive more than 10% of the allowed dose limit.
Radiation dosimetry is the calculation of the dose absorbed into tissue that results from exposure to ionizing radiation. Without this technologist wearing a dosimeter, they cannot prove it or prove that there was never a malfunction in the equipment or some other oddity in which they were exposed to excess radiation. This also serves as a reminder that if you are issued a personnel dosimetry, it is because DRS believes you have a dose potential to receive 10% (or more) of the allowed radiation dose limit. All personnel dosimeters should be evaluated at least quarterly or immediately after replacement, whichever is most common.
If the personnel dosimeter required by regulations is lost or damaged, the worker must immediately cease work until a replacement personnel dosimeter is provided that meets the requirements of regulations and the exposure is calculated for the time period from issuance to loss or damage to the personnel dosimeter. For personnel dosimeters that do not require processing, the dosimeter evaluation should begin within 24 hours.