Phy-X/ZeXTRa: a software for robust calculation of effective atomic numbers for photon, electron, proton, alpha...

The purpose of the present work is robust calculation of effective atomic numbers ([Formula: see text]s) for photon, electron, proton, alpha particle and carbon ion interactions through the newly developed software, Phy-X/ZeXTRa (Z_eff of materials for X-Type Radiation attenuation). A pool of total mass attenuation and energy absorption coefficients (for photons) and total mass stopping powers (for charged particles) for elements was constructed first. Then, a matrix of interaction cross sections for elements Z = 1-92 was constructed. Finally, effective atomic numbers were calculated for any material by interpolating adjacent cross sections through a linear logarithmic interpolation formula. The results for [Formula: see text] for photon interaction were compared with those calculated through Mayneord's formula, which suggests a single-valued [Formula: see text] for any material for low-energy photons for which photoelectric absorption is the dominant interaction process. The single-valued [Formula: see text] was found to agree well with that obtained by other methods, in the low-energy region. In addition, [Formula: see text] values of various materials of biological interest were compared with those obtained experimentally at 59.54 keV. In general, the agreement between values calculated with Phy-X/ZeXTRa and Auto-Zeff and those measured were satisfactory. A comparison of [Formula: see text] values for photon energy absorption calculated with Phy-X/ZeXTRa and literature values for a nucleotide base, adenine, was made, and the relative difference (RD) in [Formula: see text] between Phy-X/ZeXTRa and literature values was found to be 2% < RD < 11%, at low photon energies (1-100 keV), while it was less than 1% at energies higher than 100 keV. Highest [Formula: see text] values were observed at low photon energies, where photoelectric absorption dominates photon interaction. For electrons, corresponding RD(%) values in [Formula: see text] were found to be in the range 0.4 ≤ RD(%) ≤ 1.7, while for heavy charged particle interactions it was 2.4 ≤ RD(%) ≤ 4.2 for total proton interaction and 0 ≤ RD(%) ≤ 8 for total alpha particle interaction. In view of the importance of [Formula: see text] for identifying and differentiating tissues in diagnostic imaging as well as for estimating accurate dose in radiotherapy and particle-beam therapy, Phy-X/ZeXTRa could be used for fast and accurate calculation of [Formula: see text] in a wide energy range for both photon and charged particle (electrons, protons, alpha particles and C ions) interactions.