The Reference Man in diagnostic radiology dosimetry

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Abstract
Following the legislation for radiation protection in Europe, increasing interest has been given to patient dosimetry indiagnostic radiology. Dose comparisons between groups of patients have demonstrated considerable discrepancies. Theequipment, as well as the procedures used, have been scrutinized in order to find the reasons for the variation and to reduce it. Inthis work, patient size and shape are considered in patient dose evaluations in diagnostic radiology. The size, shape and constitution of the patients are shown to relate exponentially to the energy imparted during examination of the trunk. Theequivalent cylindrical diameter of the patient body is used as the independent variable. Exponential functions are created by linearregression. The ICRP Reference Man with an equivalent diameter of 22.9 cm is used as a body-size standard. A method issuggested by which coordinate transformations reduce data to a base line defined by the Reference Man. It is shown that themethod reduces the range of energy imparted by between 30% and 60% for six common X-ray examinations of the trunk. Resulting data constitute a finer instrument for intercomparisons between hospitals for the same examination. Further, it issuggested that adipose tissues should not be included when detrimental effects of radiologic exposure are determined. TheReference Man, stripped of 10 kg subcutaneous adipose tissue, is used as the non-fat standard dimension corresponding to theequivalent cylindrical diameter 21.2 cm. The suggested method is used to estimate the fraction of energy imparted to vital organsonly. The results show that the energy imparted is reduced by between 30% and 60% according to this model. Consequently,predicted deaths are reduced by the same amount.