Dosimetry

EH&S issues dosimeters to individuals who are required to be monitored for occupational exposure to radiation.

Employees working with radiation producing machines or radioactive materials are subject to annual dose limits, and the University must control the dose they receive. EH&S’s Radiation Safety team issues dosimeters to individuals so the occupational exposure they receive can be monitored by the Radiation Safety Committee and be kept as low as reasonably achievable. It is important that UW personnel who are monitored for exposure return their dosimetry in a timely manner.

What you need to know

Dosimeters monitor external radiation exposure and, after processing, provide a permanent, lifetime record of occupational dose. Federal and state regulations require the University to provide monitoring for anyone that could receive 10 percent of the maximum annual occupational dose.

Dosimeters available

Two main types of dosimeters are available, plus specific types for certain types of work.

Whole body dosimeter

Worn on the front portion of the trunk of the body between the waist and shoulders and in approximately the same location each wear period.
If you regularly wear a lead apron, you may be assigned two whole body dosimeters. One should be worn at your waist, under the lead. The other is worn at your collar, over the lead. Be sure to check the dosimeter so that you wear the appropriate dosimeter at the correct location.

Extremity dosimeter

A ring that should be worn on your dominant hand.
If you are assigned two rings, they are marked and should be worn on the correct hand for accurate exposure readings.
The ring should be worn under your gloves. Care should be taken to ensure the ring is not removed with the gloves and disposed.

Storage

When not in use, dosimeters should be kept in an area with low background radiation, such as a badge board (designated area for storage), desk drawer or locker.

Dosimetry series

Personnel are assigned to a dosimetry group, called a "series", based on the lab, clinic or group they belong to. Each series is assigned an Area Dosimetry Coordinator, who is responsible for issuing, collecting and returning dosimetry to EH&S at the end of a wear period. The coordinator must also keep Radiation Safety informed of changes to personnel assigned to the series.

Returning dosimeters for processing

To ensure timely notification of high exposures and compliance with regulations, please return your dosimeters(s) to your area dosimetry coordinator before the 15th day of the month following each wear period.

Unused dosimeters A picture of a dosimeter without the plastic tab broken

Dosimeters that are returned without the top plastic tab broken are considered unused and the dose measured on the dosimeter will not be assigned to the individual. Therefore, please break the plastic tab on top of the dosimeter, and place it in a dosimeter holder.

What you can do to stay safe

Wear your dosimeter in the appropriate location
Return your dosimeter to your area dosimetry coordinator promptly (within 15 days of the end of the wear period)