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D J Strom

Publications and source records attributed to D J Strom.

6 recordsLinked to original sources
PubMed1992

Minimum detectable activity when background is counted longer than the sample.

This note discusses the use of blank or background counting data that are measured for times that differ from times used for the sample counts. The correct formula for the minimum detectable activity, under this condition, is given as follows: MDA = [3 + 3.29 square root of Rbtg(1 + tg/tb)]/epsilon tg, where Rb denotes background count rate, tb and tg denote background and gross count times, and epsilon denotes counting efficiency. Counting backgrounds for a long time reduces decision levels, uncertainties, and minimum detectable activities. These benefits are fully available only when there is no other source of variability than random fluctuations in count rates.

Background Radiation↗
PubMed1986

Estimating individual and collective doses to groups with 'less than detectable' doses: a method for use in epidemiologic studies.

Distributions of annual external doses to worker populations are often found to be distributed lognormally below 15 mGy (1.5 rad). Using the properties of the lognormal distribution, and starting from individual dosimeter results, a method is presented whereby estimates can be made of collective and individual doses "missed" due to the fact that dosimeters have a threshold of detection or minimum detectable dose (MDD). For the case where only annual dose totals are available for a population, if MDD results were recorded as zero and if monitoring was done on a quarterly basis, the method developed is shown to yield reasonably good estimates of "missed" collective dose. For the other cases of only annual totals being available (i.e. monitoring was done more frequently than quarterly, or MDD results were recorded as equal to the MDD), it is shown that the method does not yield useful results. The estimates developed here may be useful in radiation epidemiology, employee relations, and in probability-of-causation calculations.

Mathematics↗