A reappraisal of existing expressions for estimating radiation output from diagnostic X-ray machines

Abstract

The considerable differences in radiation output from different X-ray machine with given kVp and mAs has led a number of expressions being proposed for skin does in diagnostic radiography each having a power dependence of the output with the peak tube voltage. The values of the exponent in the power expression and the proportionality constant have been the subject of debate for sometimes now. Investigations were therefore undertaken to reappraise these expressions in the light of recent measurements. The values of the power exponent n obtained in the investigation compared favourably with range of 2 to 4 reported in the literature. However, the actual values of n and k are machine specific. The results also show n increasing with decreasing total filtration T and that the age of the X-ray tube affects the radiation output through n. It is therefore suggested that for the optimization of radiation dose to patients in diagnostic radiography, a proper quality control programme should include the routine measurement of radiation output for each X-ray machine. This should be repeated regularly as the machine ages and should be carried out for each time the tube total filtration is changed. In each case a tissue equivalent phantom that simulates the scattering from the patient should be used.

Nigerian Journal of Physics Vol. 16(2) 2004: 30-34