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April 24, 1972

Medical News

JAMA. 1972;220(4):469-478. doi:10.1001/jama.1972.03200040005003

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'Mean genetic radiation' declines despite increased x-ray use  The mean annual genetically significant dose of radiation received from diagnostic x-rays in the United States dropped about 35% in the six years from 1964 to 1970.This occurred despite considerable increases in diagnostic x-ray use during that time, according to preliminary results of a federal survey.Reasons for the improvement are several: the main ones probably include improved colimation, a decrease in the use of mobile x-ray units, and a relatively stable x-ray examination rate for males under 65.There was a decline in the expected future number of children, due to a decrease in the US birth rate in recent years.This latter factor is one of several considerations that goes into the complex computation of a mean genetically significant dose (GSD) for the population at large. Other major factors in computing this are mean gonad dose and frequency