The main objective of this paper is to calculate semi-theoretical values for the L-shell X-ray intensity ratios I L i / I L α (i = β and γ) across a broad range of elements in the atomic number range 36 ≤ Z ≤ 92 and photon excitation energies spanning from 1.916 keV to 200 keV. These values are derived from theoretical calculations and subsequently refined using an advanced interpolation approach based on a three-dimensional function incorporating atomic number Z and excitation energy E. The dependence of the L-shell intensity ratios on the incident photon energy is analyzed, highlighting variations across different elements. A comparison was carried out for selected excitation energies of 22.6 keV and 59.54 keV, integrating weighted average values, theoretical calculation, and experimental data from the literature to evaluate their reliability and accuracy.