Estimation of dose received when dosemeter results are recorded below a threshold level

During the course of personal radiation monitoring, the results of dosemeter measurements may fall below a threshold level and the numerical value of the dose estimate is not retained in the record. A method of estimating such doses is presented based on the presumption of a log-normal distribution of received doses; the fraction of dosemeter results for a period recorded below the threshold level together with the population geometric standard deviation is used to provide individual total dose estimates. Sample data sets of dosemeter results from two establishments are shown to have similar distributions with the combined sample having a geometric standard deviation of 2.07 ± 0.44. Data are presented to show the population dose estimates are unbiased and the total dose estimate for any person is unlikely to deviate from the true value by more than about 20% due to individual variation in distribution of dose from that for the population. (author)