Simulated superficial and deep tissue doses using niobium filtration for cephalometric radiography

The effect of added niobum filtration 30 μm and 50μm on constant potential and conventional full-wave rectified cephalometric units was explored in terms of radiation dose. Water was used to simulate soft tissues to attenuate the X-ray beam. The addition of niobium 30μm and 50μm for each unit caused a reduction in the surface dose, but resulted in an increase in the dose deep to 8 cm of water. The more heavily filtered beam reduced the surface dose most for each operating potential, while, providing the highest deep dose through 8cm of water in each case. There was a comparatively strong linear association between half-value layer (HVL) and relative dose at both the zero and the 8cm thicknesses of water. The coefficients of determination (r²) and the significant probabilities of correlation coefficient (p) were 0.82 (p<0.0001) at the surface and 0.89 (p<0.0001) with 8cm of water.