Photon atomic parameters of nonessential amino acids for radiotherapy and diagnostics

Photon attenuation parameters of non-essential amino acids using EPICS2017 library interpolations

Mass attenuation coefficients, effective atomic numbers, electron densities and energy absorption and exposure buildup factors for the non-essential and conditionally non-essential amino acids including alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, and tyrosine have been acquired using the latest evaluated photoatomic library of EPICS2017. The library was used by constructing an interpolation script that calculates for all photon attenuation parameters. Comparisons were made using alternative Monte Carlo simulation results for 15 energy points from 59.5 to 1333 keV, and in contrast with experimental works in literature. Good agreements for the mass attenuation coefficients were observed between EPICS2017-based values compared with Monte Carlo code and experimental results. Similar trends for the effective atomic numbers and electron densities were observed from EPICS2017 interpolation and from results found in literature. Conversely, buildup factors acquired by Geometric-Progression fitting parameters were reported in this work preliminarily for most of these biomolecules at different penetration depths. Overall, cysteine showed the most significant deviation among the other non-essential amino acids due to the presence of sulfur in its molecular structure.