PRODUCTS:
Control Dosimeters

Use of Control Dosimeters.

Control dosimeters are used to measure exposure from non-occupational sources such as natural background radiation and irradiation that may occur during badge shipment. They are issued with all dosimeters for a specified wearing period.

A complementary control dosimeter is provided for each type of dosimeter in your account for a given wear period. If all your group dosimeters are stored in the same area when not in use, this is sufficient. If you have multiple locations where you store dosimeters when not in use, or you ship badges to remote locations, a minimum of 1 additional control dosimeter per location is recommended. If you do not request additional control dosimeters, the one control from the wear period will be used from your account if they are returned together. This may result in reporting higher or lower radiation dose on all the dosimeters maintained in other locations. CHP Dosimetry strongly recommends you purchase additional control dosimeters for additional storage areas.

Control dosimeters should be stored in a location away from radiation sources at your facility. Break rooms and reception areas are good examples of appropriate storage locations. Never store controls in a lead box or a safe. These locations may have higher or lower background radiation which will impact your reported doses. The idea is that they are stored in a location that has a natural background radiation representative of your physical location for the time period the dosimeter is issued. Proper use of the control dosimeter is crucial for the accurate analysis of your personnel dosimeters.

Never issue a control dosimeter to an individual or use it as an area monitor.

FAQ’s:

1. What does it mean that my control dosimeter records a dose?
   Control dosimeter measure background radiation. Background radiation is present everywhere on earth at differing levels. Control dosimeters typically measure a background between 5-20 mrem per month.
2. What is the role of the measurement recorded on the control dosimeter in calculating occupational exposure?
   The dose measured by a control dosimeter is subtracted from all associated dosimeters and is the sum of the dose measured in transit and storage of the dosimeter. We subtract the control dosimeter response from the occupational dosimeters to determine the occupational exposure.
3. What happens if I return a badge without a control dosimeter?
   Dosimeters returned without controls will result in reporting of background and transit radiation as occupational exposure. This will always result in a positive occupational exposure. For this reason we suggest you purchase at least one additional control dosimeter for each location and wear period to send back with any early or late return shipments.
4. What happens if I send badges to a different area or facility with no control dosimeter?
   If the background radiation is different, the difference will not be accounted for, and the resulting occupational exposure will be higher or lower depending on the background radiation at that facility.