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External Monitoring

The NIH monitors external personnel​ exposures through the collection and analysis of personnel dosimeters or badges​​ on a minimum of a quarterly basis. ​Required dosimetry is based on the nature and frequency of radionuclide or radiation source usage and is not necessary for all uses of radioactive materials or radiation sources at the NIH. ​​

The Division of Radiation Safety performs minor and major exposure investigations and maintains records on the DRS database.​​​​​​

Dosimetry Requirements


​All radiation workers at the NIH must submit a new Dosimeter Evaluation Form to the Division of Radiation Safety  following registration in the DRS database. 

Completing this worksheet will ensure that the occupational worker’s need for dosimetry can be evaluated appropriately. If it is unknown what radionuclides and amounts will be used, the Individual User (IU)​ should ask the Authorized User (AU) for guidance. ​

Based on the activity and encapsulation or form of the radionuclide, dosimetry may be required for use of the following radionuclides*:​

*not a comprehensive list

Due to the very low energy of emission, dosimetry is NOT required for use of the following radionuclides*:​

 *not a comprehensive list

Other activities that may involve exposures to radiation or radioactive material and require a dosimetry evaluation by the DRS include*:

  • Patient care during radionuclide therapy 
  • Animal research involving radiation or radioactive material 
  • Positron emission tomography (PET) radionuclide production and compounding 
  • Nuclear Medicine / PET imaging 
  • X-ray and fluoroscopy machine procedures 
  • Cyclotron operation 
  • Linear accelerator therapy 

*not a comprehensive list

Before occupational radiation workers engage in these activities, they are required to submit​​ a Dosimetry Evaluation Form to ensure proper dosimetry evaluations are made and dosimetry is issued, if necessary.   ​


​Dosimetry Use, Storage, and Maintenance

Dosimetry is used to monitor occupational radiation exposure only and should not be worn outside of work, taken home, or otherwise exposed to radiation sources outside of NIH facilities. Dosimetry should not be left in closed cars due to exposure to sun or heat, and should not be subjected to chemicals that could damage the dosimeters. 

Dosimeters issued to individuals should be worn properly at all times when working with or around radioactive materials or sources of radiation. When not being worn, dosimetry should be stored away or shielded from sources of radiation.  

Dosimetry is not to be worn during medical procedures or following diagnostic imaging involving radioactive material. The area health physicist​ should be contacted if there are questions about any inadvertent exposures to the dosimeter.

Download the DRS Dosimetry Handling and Care Reference Guide​

Dosimetry Results

Personnel dosimetry results are obtained from the dosimetry contractor and reviewed by the DRS. DRS provides results to wearers annually and upon signed, written request to the address below. The request should include your full name, date of birth and/or NIH ID, and dates of employment at NIH. ​​

Personnel Dosimetry Program Manager 

National Institutes of Health 

Division of Radiation Safety 

21 Wilson Drive, MSC 6780 

Bethesda, MD 20982-6780 

Elevated Exposures​

The DRS may conduct an investigation of elevated exposures based on predetermined trigger or action levels​. Exposure investigations are not a cause for alarm, as they are most often conducted for exposures that are within regulatory limits. Investigations will determine the cause of an elevated exposure, identify corrective actions, and ensure that future radiation exposures are as low as reasonably achievable (ALARA)​. ​