Assessment of Dose to the Gonads Outside Diagnostic X-ray Beams

The distribution of scatter outside the beam was investigated for 80 and 140 kV X rays. Scatter outside depends predominantly on geometry and self-absorption in the layer between the near edge of the beam and the point of reference. Correction for geometry is obtained by referring scatter to the angle subtended at the point of reference by the near edge. By correcting in this way absorption coefficients for scatter were determined. For a given object radiographs of the same contrast are shown to require the same surface dose. Since scatter per unit surface dose rises with kilovoltage, scatter per radiograph of the same contrast increases with higher kilovoltage. Only with reduced contrast may gonad dose be decreased. A method of calculating scatter doses outside the beam is described.