The purpose of personnel monitoring is to provide early notice if your exposure is not below the limits and ALARA. The monitoring program also provides a permanent record of your exposure.
Types of dosimeters
There are two primary types of dosimeters worn by persons who work with or near sources of radiation. The film badge is film wrapped in light‐tight paper and is mounted in plastic. Badges are checked periodically, and the degree of exposure of the film indicates the cumulative amount of radiation to which the wearer has been exposed. Thermoluminescent dosimeters (TLDs) are crystalline solids that trap electrons when exposed to ionizing radiation and can be calibrated to give a reading of radiation level. Film badges are most often worn by hospital staff potentially exposed to x‐rays or researchers working with higher energy beta emitters. TLDs are most often worn by persons exposed to a variety of isotopes such as found in nuclear medicine or the cyclotron facility. All dosimeters are processed by a contractor. They are collected the first week of every wear period. Most monitors can read as low as 10 millirem.
Monitoring required
The regulations require monitoring for any worker who might exceed 10 percent of the applicable limit, and any worker entering a high or very high radiation area. Monitors are usually recommended for projects authorized to 5 millicuries of photon‐ or high energy beta‐emitters, and XRD operators. Dosimetry will be issued when evaluation establishes a need for the use of this monitoring technique. Requirements will be stated in the Hazards Evaluation. See Table 2.1 for the dose limits.
Records of Prior Exposure
Each individual having a previous or on‐going radiation exposure history with another institution is required to submit an “Authorization to Obtain Radiation Exposure History” form.
Use
Body badges and finger rings are worn where the highest exposure is expected; rings are worn underneath gloves to avoid contamination. If you are supplied both types, wear both whenever you are working with radiation. Health Physics can provide alternative guidance in unusual situations.
Precautions
Do not wear for non‐work exposures such as a dentist’s office.
Store badges in a safe location when not in use, away from sun, heat, sources of radiation or potential damage. Protect badges from impact, puncture, or compression.
Do not store Extremity (finger) rings in lab coat pockets. Storing rings in the lab coat pocket may expose the rings to radiation measured by the whole body badge. Rings are to measure hand exposures only.
A missing or invalid dosimeter reading creates a gap in your radiation dose record and affects the monitoring program’s ability to provide accurate exposure readings. For a missing dosimeter a “Lost/Damaged Dosimeter Report” is required.
ALARA Limits
Level I will be reported to the individual. Level II requires an investigation and will be reported to the appropriate committee. (Refer to HPM 7.5)
Bioassays
Individuals who handle large amounts of volatile radionuclides may be required to participate in a bioassay monitoring program.
If you routinely handle one millicurie or more of radioactive iodine, you are required to come to Health Physics to have your thyroid monitored for uptake. The thyroid measurement should be within 72 hours following exposure and every 2 weeks if routine work continues. The bioassay should not be sooner than 6 hours.
The bioassay requirement for each project is described in the Hazards Evaluation. Note that thyroid blocking agents will not be permitted.
If you handle more than 100 millicuries of tritium, you are required to submit a urine sample to Health Physics seven to fourteen days after the experiment. The sample will be measured for tritium content. Please make arrangements with health physics prior to beginning work.
Bioassays may also be ordered by the RSO after a spill, an unusual event, or a procedure that might result in an uptake.
