Quantitative Analysis of the Reduction in Organ Doses in Diagnostic Radiology by Means of Entrance Exposure Guidelines

Abstract

One prudent objective in diagnostic radiology is to limit the absorbed dose to radiosensitive organs to that required to obtain the necessary clinical information. There is a proportionality between entrance exposure and organ dose for a radiographic procedure in which all other technique factors and the exposure geometry are held constant. Because of this proportional relationship and because entrance exposures are relatively easy to measure, the idea of setting limits on entrance exposures has appeared to be a reasonable method of reducing doses to internal organs. The Bureau of Radiological Health (BRH) is currently evaluating the concept of entrance exposure guidelines. The ultimate purpose of proposed guidelines for entrance exposures is to minimize organ doses and thereby minimize the risks of delayed somatic and genetic illnesses. Thus, the quantitative relationship between the reductions in organ dose afforded by entrance exposure guidelines is a critical piece of information in estimating the impact of this approach. The intent is to set exposure guidelines based on previous information on exposure distributions observed in actual practice. It is not intended that as more x-ray facilities reduce their entrance exposures, the exposure guidelines would be continually lowered to accommodate this shift. The exposure guidelines shoudlmore » be relatively constant, subject to periodic review.« less