Monitoring Radiation Exposure

The Office of Radiation Safety is responsible for monitoring individuals who are occupationally exposed to radiation. State regulation requires that any individual who is likely to receive a dose of 10% or more of the annual limit must be monitored for radiation exposure.

Film or TLD badges (dosimeters) are the most common means of monitoring personnel for radiation exposure. Several types of dosimeters are available to accommodate the variety of individual needs. The most common types are:

• Monthly Film Badges - These badges are designed to monitor for whole body exposure and are worn for a period of one month before replacement. Monthly badges are used in areas where exposures could reasonably exceed 10% of the annual limit (0.5 rem/year or 500 mrem/year), and doses must be carefully watched.
• Quarterly Film Badges - These badges are designed to monitor whole body exposure and are worn for a period of three months before replacement. Quarterly badges are used in areas where exposures are not likely to exceed 10% of the annual limit, but where it is prudent to keep track of exposure.
• Finger Ring Badges - These badges are designed to monitor extremity exposure and are worn for one or three months, as appropriate. Finger badges are assigned to personnel who handle significant quantities of radioactive materials or whose hands are placed near the direct beam from an x-ray machine.

Individuals, who are monitored on a monthly basis, or for exposure to the embryo/fetus, are closely tracked to ensure that exposure does not exceed the limits. Any badge wearer whose whole body monthly exposure exceeds 100 mrem, or 25 mrem for pregnant employees, receives a high exposure memo. This memo informs the wearer of the exposure received and requires a written response from the wearer as to the circumstances under which the exposure may have occurred. Individuals who receive high exposures are monitored and every effort is made to reduce exposure where possible.

It is important that personnel who are assigned film badges wear them properly. Dosimeters designed to measure whole body exposure should be worn at the area that will receive the highest exposure. Most frequently, whole body badges are worn at the waist or at the collar. When protective aprons are worn, the badge must be worn at the collar, outside the apron. When not on duty, badges should be left at the workplace in a cool, dry location, away from any sources of radiation. If a dosimeter is exposed when not being worn, the record will indicate a higher exposure than the individual actually received. Storage of badges in the control room of an x-ray installation is not recommended. If a badge has been left inside an x-ray room, it must be reported immediately to the Office of Radiation Safety.

If a dosimeter badge is lost or damaged, please report this to the Office of Radiation Safety immediately. A replacement must be assigned as quickly as possible.

Dosimeters are distributed by the Office of Radiation Safety in groups called locations. Each location contains personnel from an individual department. The location leader is the person assigned to distribute and collect badges from the individual users. Reports of personnel monitoring must be posted where each individual user may keep track of exposure. Personal information (Social Security numbers, birthdates, etc) is not printed on posted reports. Contact the department location leader for the location of monitoring reports.

 Previous | TOC | Next