Guidance on the Use of Control Monitors
A Control monitor is issued with each batch of personal monitors. The Control monitor gives a measure of the background radiation level or transit dose to which the batch as a whole is exposed. Any reading from a personal monitor that is above that of the control is assumed to be due to occupational exposure. 
Monitors should be stored in a visible and easily accessible location away from radiation sources, preferably on a Badge Board. A Badge Board allows for storage of a control monitor with personal monitors when they are not in use, which allows for more accurate calculation of wearer dose.
A Badge Board would preferably be located close to the entrance of the work area. This helps to remind wearers to remove their badge before leaving for the day. The use of a Badge Board also makes it easier to change over monitors at the end of the wearing period. 
Control monitors for Thermoluminescent Dosemeters (TLD) should not be stored in a holder. Control monitors for Special TLDs, Neutron Monitors, and Extremity monitors should be stored in the holder in which they are provided.

monitors sent out

background radiation level

work environment radiation level

actual wearing periods

monitors returned

time

Dose Rate

Control Monitor