This work deals with the evaluation of interaction cross sections, effective atomic number, and effective electron density at gamma photon energies, not available from standard radioisotopes. The Compton scattering technique is used to obtain the required gamma energies within a specific range of energies from 241.8 to 401.8 keV to perform the radiation measurements. Radiation interaction parameters of some inorganic compounds (high-Z rare-earth nitrate hexahydrate), namely, Lanthanum(III) nitrate hexahydrate [La(NO3)3.6H2O] and Samarium(III) nitrate hexahydrate [Sm(NO3)3.6H2O], soluble in low-Z organic solvent (acetone) are evaluated. Six scattering angles are chosen to obtain six (not available from standard radioisotopes) Compton scattered energies to perform narrow-beam transmission experiments. An NaI(Tl) scintillation detector is used to detect the transmitted flux from the different solutions in various proportions. Photon interaction parameters useful in vast basic and applied fields are evaluated. The present measured results, obtained from the Compton scattered technique, are found to be in good agreement with the computed values of radiation interaction parameters obtained from the WinXCom program. The present data on rare-earth solutions have definite scientific importance in nuclear and radiation physics and fill in the gap of nonavailability of such data for radiation workers at these specific energies.