A re-evaluation of the 'saturated scatter' method for estimating the energy imparted to patients during diagnostic radiology examinations.

Central-axis depth dose data for diagnostic qualities (1-4 mm Al HVL) have been used to calculate the total energy imparted to patients or phantoms during X-ray examinations. A 'saturated scatter' method has been used and allowance is made for the finite dimensions of the patient by using PDD data for large but finite field sizes. For the purpose of integration, PDD data have been represented as a function of depth by two exponential components. Data in the form of energy imparted per unit central-axis surface dose and per unit surface X-ray field are tabulated as functions of kVp, first HVL, phantom thickness and the field size of the original PDD data. Comparison with energy fluence calculations of total energy imparted made by other workers indicates good agreement under similar phantom and X-ray quality conditions, although it is noted that anatomical variations between patients will in practice lead to uncertainties in the total energy imparted.