  Radium-226 in the human body poses unique problems for whole body counters. People who have accumulated this nuclide only because of the minute amounts occurring naturally in food and water have counts of only two or three disintegrating atoms per second, and this amount cannot be distinguished from background radiation. Whole body counters are useful, however, in diagnosing effects in persons who have been overexposed to radium. These include Figure 10 A group of radium dial painters at work in a watch factory in 1922. Almost all these employees have been identified and the living ones recently have participated in a study at Argonne National Laboratory to determine the extent of radium accumulation in their bodies. Whole body counters aided in their examinations. Excerpts from case records of one research center show the high counts found in several patients and the source of the radium or thorium (a closely related element) that their bodies had taken up:
Scientists at the Argonne National Laboratory, Argonne, Illinois, have attempted to improve crystal whole body counters so that they will be more useful in determining the amount of radium-226 in humans. Rolf Sievert at the Swedish Atomic Energy Commission also has studied the radium-226 detection. He devised a highly accurate whole body counter with 10 ion chambers arranged around a curved aluminum bed on which the subject rested. The instrument was installed below ground to reduce the interference of background radiation. Figure 11 The spectrum of gamma radiation emitted by the body of a man three years after he accidentally inhaled radium-226. The solid line shows the normal radiation due to potassium-40, the dotted line the total from potassium-40 and radium-226. |
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