Impact of level density models on the calculation of some theranostic radionuclides using EMPIRE code

Abstract

Radioisotopes such as ⁶⁷Cu, ¹³¹I, and ^99mTc are used in nuclear medicine for diagnostic and therapeutic (theranostic) applications. Cross-section data for the nuclear reactions that produce these radioisotopes are essential for efficient production; however, experimental cross-section data remain limited for these isotopes. The reaction cross sections of the radioisotopes ⁶⁷Cu, ¹³¹I, and ^99mTc were evaluated using the nuclear reaction model code EMPIRE 3.2.3. The influence of nuclear level density (NLD) models on energy-dependent cross-section calculations was investigated for the reactions ⁶⁸Zn(p,2p)⁶⁷Cu, ⁷⁰Zn(p,alpha)⁶⁷Cu, ¹³⁰Te(d,n)¹³¹I, ¹⁰⁰Mo(p,2n)^99mTc, and ¹⁰⁰Mo(n,2n)⁹⁹Mo within an energy range from threshold to 70 MeV. Calculated energy-dependent cross-section functions were benchmarked against experimental data from the EXFOR database and evaluated nuclear data from International Atomic Energy Agency (IAEA) libraries. The results show clear sensitivity of the predicted cross sections to the selected NLD model. The cross-sections predicted by the nuclear level density models that showed the best agreement with the experimental data were 32 MeV (6.80 mb) for ⁶⁸Zn(p,2p)⁶⁷Cu, 17 MeV (17.79 mb) for ⁷⁰Zn(p,alpha)⁶⁷Cu, 12 MeV (99.94 mb) for ¹³⁰Te(d,n)¹³¹I, and 18 MeV for both ¹⁰⁰Mo(p,2n)^99mTc (994.78 mb) and ¹⁰⁰Mo(n,2n)⁹⁹Mo (1500 mb). Radionuclidic purity indices ranged from 1.93% to 17.27%, depending on the reaction channel. These results demonstrate the reliability of EMPIRE 3.2.3 for predicting cross sections and provide useful nuclear data for radionuclide production.