18.0 Personnel Monitoring

Personal monitoring is required for the persons who are likely to receive a dose in excess of the UNR's administrative limits or 10% of state occupational dose limits.

18.1 How to Obtain a Dosimeter

Anyone who received radiation safety training and who is likely to receive 10% of the state occupational dose limits may request personal monitoring. The requesting personnel must complete the dosimeter request form and send it to EH&S. The dosimeter request form is available from the EH&S web page and office. Dosimeter delivery may take one week to two weeks from receipt of dosimeter request form.

NOTE: Those persons wishing to provide dosimetry to their students for class or laboratory activities must make special arrangements with EH&S.

18.2 Personal Dosimeter Use Procedure

  1. Dosimeters will be worn ONLY by persons to whom they are issued. They must NOT be loaned to another person, nor used for area monitoring. (Area monitoring is available from EH&S).
  2. The whole body dosimeters should be worn in the central chest region.
  3. Ring or wrist dosimeters are issued to persons who use a high energy beta source. Ring dosimeters should be worn on the finger which is nearest the radiation source, usually the index finger, with the sensitive portion of the badge toward the radiation source.
  4. Wear the badge whenever working with or around radiation sources. Do not wear a dosimeter when undergoing medical or dental diagnosis or therapy, since your nonoccupational dose is not regulated by the State Radiation Control Program Office, and is not to be included as part of your dosimetry results.
  5. Use care when leaving the lab to place the dosimeter on the rack located in your lab so that dosimeters are not left in exposure areas such as an accelerator target room. If a dosimeter is exposed in this manner, the dosimeter must be changed without delay since the dose should not be ascribed to the wearer. Return the badge to the RSO with an explanatory note.
  6. The dosimeter must be placed on a designated dosimeter rack in the laboratory for periodic exchange. Delay in returning a dosimeter results in considerable extra work and correspondence during follow up. A dosimeter which is returned late cannot be processed with the control dosimeter supplied with the shipment.
  7. Do not remove the dosimeter from the facility.
  8. The user must notify the RSO before undergoing any nuclear medicine studies or treatments or before returning to work and wearing their dosimeter after such studies or treatment.
  9. If the dosimeter is lost or damaged, a record of the incident will be made in order to document the period of time for which the exposure data was lost.

NOTE: A dosimeter must be processed immediately whenever serious exposure is suspected. Call the RSO if such circumstances arise.

18.3 Records

18.3.1 Personnel Exposure Record

Personnel exposure data will be sent to each group or department to be available to dosimeter wearers when reports are received. Personnel exposure data shall be part of the permanent records of the EH&S Department. Upon written request by any wearer, EH&S will provide a copy of the individual's exposure history.

18.3.2 Records of Prior Exposure

Employees or students requiring personal dosimetry will be required to complete the appropriate form indicating all locations where previous radiation exposures may have occurred. With the signed consent of the employee, a letter will be sent to the indicated facility or facilities requesting prior exposure history. Falsified statements or refusal to provide this information will result in denial, or termination of Authorized User status.

18.4 Internal Dosimetry

Bioassays may be required at the discretion of the RSO. As a general principle, bioassays will be required after any incident (e.g., contamination of personnel or exposure of persons to airborne radioactivity) where the possibility of internal deposition of radioisotopes exists. Bioassays include such tests as radioanalysis of blood, urine, fecal samples, nose swabs or sputum. In addition the term bioassay includes whole body or thyroid counts. Bioassay service is available at any time upon the request of the User. Thyroid counts (which takes only a few minutes) or other bioassays may be arranged by calling the RSO at 784-4540.

18.4.1 Bioassay for Users of Radioiodine

Any person who works with forms of radioiodine where iodide ions or uncombined iodine might be present in quantities which equal or exceed the values in the table given below are required to have bioassays at intervals deemed appropriate by the RSO according to the Regulatory Guide 8.20 (Revision 2 dated September 2014).

Activity above which bioassay for I-125 or I-131 is necessary: activity handled in unsealed form
Type of operation Volatile or dispersible* Bound to non-volatile agent
Processes in open room or bench, with possible escape of iodine from process vessels. Not allowed 1 mCi**
Processes with possible escape of iodine carried out within a fume hood of adequate design, face velocity and performance reliability 1 mCi** 10 mCi**
Processes carried out within glove boxes, ordinarily closed, but with possible release of iodine from process and occasional exposure to contaminated box and box leakage. 10 mCi** 100 mCi**

*Volatile radioiodine will only be handled in fume hoods or other systems which have been inspected and approved by the RSO.

**Quantities in this table are cumulative amounts handled during a three month period.

  1. Anyone working with levels within the above limits will have a baseline bioassay performed within two weeks prior to beginning work with radioactive iodine.
  2. When an investigator is terminating his work with radioiodine, a bioassay will be performed within two weeks of the last possible exposure to I-125 or I-131.
  3. Whenever an individual is found to have a thyroid burden in excess of 0.12 uCi of I-125 or 0.04 uCi of I-131, the RSO may take the following action:
    1. Complete a thorough evaluation of all aspects of the iodination procedure.
    2. Restrict the worker from further exposure until the source of exposure is discovered and corrected.
    3. Repeat the bioassay periodically to obtain an individual effective half-life and to determine committed effective dose equivalent.
    4. Refer the individual to appropriate medical consultation for recommendations regarding therapeutic procedures that may be carried out to accelerate removal of radioiodine from the body.
    5. Make reports of notifications as required by the State of Nevada Regulations.

Personnel are required to call the RSO whenever they suspect that they might have been exposed to airborne radioiodine or if they believe that they might have ingested or otherwise allowed radioiodine to enter their bodies.

18.5 Medical Surveillance Policy

Personnel will be placed under medical surveillance when their potential exposure to ionizing radiation is such that somatic biological effects susceptible to detection by a medical evaluation could occur. Such appraisal will include an acute and chronic exposure evaluation and will consider many variables (duration, source, type of potential exposure, etc.). Personnel requiring medical surveillance will be referred to an examining physician by EH&S.


18.5.1 Medical Records and Examination

  1. It is the policy of the University of Nevada, Reno to qualitatively and quantitatively determine internally deposited radioisotopes.
  2. Examinations will be made of any student or employee who is suspected of, or known to have, ingested, inhaled, or absorbed radioisotopes. Urine radioanalysis, thyroid counting, and eye examinations may be included. Radiation workers shall be scheduled to appear at a prearranged time for the prescribed analysis.
  3. Medical records will consist of the following:
    1. Any measurement made to detect internally deposited radioisotopes.
    2. Information necessary to assess exposure.
    3. Personnel dosimetry records.
  4. Copies of medical examination records will be maintained in EH&S and coordinated with personnel dosimetry data.

18.6 Visitor Dosimetry

Visitors are not normally allowed in restricted areas. Prior arrangements have to be made between the RSO and the AU, if there is a need to have visitors in a restricted area. The RSO will arrange appropriate dosimetry as required.

19.0 Procedure when Exposure Limits are Exceeded