Radiation Doses in Diagnostic X-Ray Procedures

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Abstract
The health physics and medical personnel of the Oak Ridge National Laboratory have conducted a study designed to determine the skin dose from x-rays at the focal point of entry and to the gonads of adult patients during certain diagnostic x-ray procedures. A record system has been inaugurated which seeks to accumulate all previous x-ray data of a personal nature and will include any future data that may accrue for the Oak Ridge National Laboratory population. The procedure for obtaining preliminary data was made rather simple in order to minimize disturbance of the work of cooperating installations. The Oak Ridge National Laboratory Medical facility, two hospitals, and two radiological clinics were the sites for initial measurements. As a preliminary expedient, doses were determined with a Victoreen Condenser R-Meter at the table-top focal points and for points at the relative position of the adult male gonads. From these preliminary measurements a typical dose was assigned for each diagnostic procedure. In the Laboratory a more elaborate study was performed, with a tissueequivalent phantom fabricated from a display manikin which had the approximate dimensions of a human adult female. The manikin, when purchased, consisted of a thin shell of papier-mache over which was placed a thin layer of plaster. To approximate human ti ssue, most of the hollow interior was filled with paraffin of a specific gravity of 0.93. Two empty polyethylene bottles were inserted in the thoracic cavity to simulat e the lungs. Cavities were made in the region of the ovaries to accommodate Landsverk Model L-82 ion chambers. A paraffin-walled receptacle for ion chambers was mounted in the region of the scrotum (see Figs . 1 and 2). Phantom measurements were made at three of the medical facilities of the Union Carbide Nuclear Company. The skin dose at the focal point of entry and the male and female gonad doses were measured. On the basis of the measurements made at the Oak Ridge National Laboratory installation, factors were applied to the early data from the two hospitals and two clinics in order to estimate the dose which might have been obtained with the phantom. Gonad doses determined from these phantom measurements are probably exaggerated, as the phantom is somewhat smaller than the average adult. Variations in skin doses for similar technics are due primarily to tube types and/or kilovoltage and milliamperage calibration. Differences in skin dose attributable to differences in target-skin distance were quite small, as these distances were for the most part within an inch of one another. The study included equipment and technics which resulted in doses comparable to both the highest and lowest reported in the literature. Doses for some of the exposures are listed in Tables I-VI. The letters A through G refer to facilities studied, and the figures to the corresponding referencescited. Table II-A is analyzed as follows:

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