There are few long-lived radionuclides yielding high intensity gamma-rays emission with energies ranging from 100 keV to 500 keV that can be applied as radioactive gamma standard to calibrate HPGe detectors. Furthermore, this energy range represents the main emitted energies of the majority of radionuclides used in nuclear medicine. The Brazilian National Laboratory for Ionizing Radiation Metrology (LNMRI/IRD/CNEN) has attempted to identify radionuclides that have the potential to be used as a calibration source due to their long half-life as well as their emission spectrum. Hence, LNMRI promotes standardization studies of gamma-emitting radionuclides that meet these criteria on order to disseminate them. Thorium-229, with its well-defined energies and relatively high intensities, is one such candidate radionuclide for the energy and full-energy peak efficiency calibration of high-purity gamma spectrometers. Thorium-229 was standardized by the method of 4παβ(LS)-γ(NaI(Tl)) live timed anticoincidence counting. The emission intensities of gamma-rays associated with the decay of ²²⁹Th have been determined by HPGe gamma ray spectrometry with accuracy and precision. The results are in agreement with current literature data.

很少有能产生100 keV至500 keV能量的高强度伽马射线发射的长寿命放射性核素，可以用作放射性伽马标准品来校准HPGe检测器。此外，该能量范围代表了核医学中使用的大多数放射性核素的主要发射能量。巴西国家电离辐射计量学国家实验室（LNMRI / IRD / CNEN）试图鉴定由于其半衰期长和发射光谱而有潜力用作校准源的放射性核素。因此，LNMRI促进了满足这些标准的伽马发射放射性核素的标准化研究，以便进行传播。ium 229具有明确的能量和相对较高的强度，是用于高纯度伽马能谱仪的能量和全能量峰值效率校准的一种此类候选放射性核素。ium 229用4παβ（LS）-γ（NaI（Tl））实时反符合计数法标准化。与γ衰变有关的γ射线的发射强度²²⁹ Th已通过HPGeγ射线光谱法准确而精确地确定。结果与当前文献数据一致。