In the interest of obtaining new polyester, heavy metal oxides PbCO3, Bi2O3, and CdO with numerous ratios have been added to the polyester resin. Five samples of labeled PR-1, PR-2, PR-3, PR-4, and PR-5 were prepared for this study. The values of linear attenuation coefficients (LAC) of the new polyester samples were measured using an HPGe detector. In the interest of ensuring the experimental setup, the value of LAC obtained from the HPGe detector as well as the value of LAC calculated using Phy-X software, have both been placed in one graph, which revealed a consistent result. The experimental value of those new polyester samples has been measured within the energy region 0.06–1.332 MeV, whereas the theoretical values have been calculated within the energy limit of 0.015–15 MeV. The results of all the new polyester samples showed an uplifting trend according to the rising energy at 0.06, 0.66, 1.17, and 1.33 MeV. At energy 0.06 MeV, sample PR-5 (ρ = 2.180 g/cm3) showed the lowest half value layer (HVL) among the polyester samples. This result is due to the addition of Bi2O3 and CdO into the samples' composition, increasing their density and enhancing the polyester's reduction ability. Considering the measured shielding parameters studied herein, it has been found that sample PR-5 (50 wt% Polymer resin, 25 wt% Bi2O3, 25 wt% CdO) had the highest shielding ability compared with the rest of the polyester samples. [ABSTRACT FROM AUTHOR]