Differences in reported backscatter factors for low-energy X-rays: a literature study

For low energy X-rays (HVL<8 mm Al) large differences (up to 10%) in backscatter factors have been reported between new Monte Carlo calculations and old measurements. Minor differences (up to 3%) have been shown between recent measurements and these calculations. These differences have been said to be caused by errors mainly in the measurements. All investigations (old and new) have presented BSF as a function of HVL. By regarding the X-ray spectra used by the different investigators the differences are explainable. Even the old BSF-values may be correct if, as presumable, they are obtained with higher voltage, larger voltage ripple and lower filtration than used by the recent investigators.