Investigation of human teeth with respect to the photon interaction, energy absorption and buildup factor

The effective atomic numbers and electron densities of human teeth have been calculated for total photon interaction (ZPIeff,NePIeff) and photon energy absorption (ZPEAeff,ZRWeffNePEAeff) in the energy region 1 keV–20 MeV. Besides, the energy absorption (EABF)(EABF) and exposure (EBF)(EBF) buildup factors have been calculated for these samples by using the geometric progression fitting approximation in the energy region 0.015–15 MeV up to 40 mfp (mean free path). Wherever possible the results were compared with experiment. Effective atomic numbers (ZPIeffZPIeff) of human teeth were calculated using different methods. Discrepancies were noted in ZPIeffZPIeff between the direct and interpolation methods in the low and high energy regions where absorption processes dominate while good agreement was observed in intermediate energy region where Compton scattering dominates. Significant variations up to 22% were observed between ZPIeffZPIeff and ZPEAeffZPEAeff in the energy region 30–150 keV which is the used energy range in dental cone beam computed tomography (CBCT) X-ray machines. The ZeffZeff values of human teeth were found to relatively vary within 1% if different laser treatments are applied. In this variation, the Er:YAG laser treated samples were found to be less effected than Nd:YAG laser treated ones when compared with control group. Relative differences between EABFEABF and EBFEBF were found to be significantly high in the energy region 60 keV–1 MeV even though they have similar variations with respect to the different parameters viz. photon energy, penetration depth.