Excitation functions for production of medically relevant radioisotopes in deuteron irradiations of Pr and Tm targets
Section snippets
Rationale
Radionuclides of rare earth elements are gaining importance as emerging therapeutic agents in nuclear medicine. They often are nearly pure Auger electron emitters that can deposit high local doses and their strikingly similar chemical properties as lanthanides make that they can be conjugated to biomolecules using a single class of chelates like DOTA [1]. Some (177Lu, 169Yb) have been included in an ongoing IAEA-CRP on “Production of Therapeutic Radioisotopes” [2] and 169Yb also attracted
Experimental
The well-known activation formula together with a standard stacked foil technique was used to determine the excitation functions of deuteron induced reactions on thin targets containing oxides of Tm and Pr. Irradiations were performed at the external beam lines of the Tohoku University (Sendai) and Vrije Universiteit Brussels (VUB) cyclotrons. The Tm2O3 (25–35 μm thick in Tm equivalent for Sendai experiments; 15–60 μm thick for VUB experiments, purity 99.9%) and Pr6O11 (250–60 μm thick in Pr
Data processing
Incident beam energy and number of particles on target were initially derived from accelerator settings and from the charge collected on the Faraday cup like target holders.
Adaptations to these values are made based on remeasurement of the cross sections of the monitor reactions natTi(d,x)48V and natAl(d,x)22,24Na over the whole energy range and comparison with recommended data. This results in a determination of incident energy and number of bombarding particles with reduced uncertainty and
Model calculations
In our previous works the codes ALICE-IPPE [18] and EMPIRE [19] have been used widely to describe lots of reaction cross sections induced by light charged particles. However, during the recent analyses of the (d,p) reactions on the isotopes 114Cd [20], 165Ho [21], 192Os [13] and some others we were confronted with large underestimations of the measured cross sections. We came to the conclusion that the experimentally observed cross sections can be described only by means of a simulation of
Results and discussion
As Pr and Tm are monoisotopic elements the derived values are physical reaction cross sections obtained by irradiation of natural targets.
Results are discussed for each activation product separately and details on the way of calculation or need for correction are given were necessary.
For the Pr targets a good correspondence between the experiments at the different accelerators is found and the results are presented as a single series for these activation products where overlap exits. Data are
Production of 141m+gNd
This radionuclide has a short lived metastate (T1/2 = 62 s, Iπ = 11/2−) that shows a nearly 100% isomeric transition to the long-lived ground state (T1/2 = 2.49 h, Iπ = 3/2+). At time of measurement all the short lived metastable nuclei have decayed and contributed to the cumulative cross section for 141gNd that is presented here. The characteristic shape of a (d,2n) reaction with a high maximum of more than 1300 mb at 16.5 MeV is found. The longer waiting time for the Sendai high energy experiments did
Production of 169Yb
Our new results up to 38 MeV are a good extension of the values for the 169Tm(d,2n) reaction measured earlier up to 21 MeV and discussed in detail in [10]. All experimental data are compared with calculations in Fig. 5. The new data show a slowly decreasing cross section above 20 MeV with a value around 100 mb. The EMPIRE-D results reproduce the high energy data quite reasonably, but they give a too high value for the near-maximum cross section. On the other hand, the ALICE-D results agree better
Thick target yields and comparison of production routes
From a fit to our experimental excitation function, integral yields were calculated for 140Nd, 139mNd and 169Yb in function of incident energies up to 40 MeV (Fig. 8).
It is clear that to benefit fully from the high cross sections over a rather wide energy range for 140Nd production (Fig. 2) dedicated “high” energy deuteron beams have to be developed. If incident energy of at least 40 MeV would be available, physical yields of 217 MBq/μAh are attainable with a thick target degrading the beam to 16
Conclusion
By correlating the measured excitation functions to assessment of monitor reactions over the whole energy region we can present here for the first time reliable values for the cross sections of Nd, Pr and Ce radioisotopes produced directly or in cumulative processes by deuterons induced reactions on monoisotopic Pr. The high cross sections values (above 1000 mb) of the (d,3n) and (d,4n) reactions allow efficient production of medically relevant radioisotopes 140Nd and 139Pr (indirect route from
References (29)
- et al.
Appl. Radiat. Isotopes
(2002) - et al.
Appl. Radiat. Isotopes
(2005) - et al.
Appl. Radiat. Isotopes
(2007) - et al.
Nucl. Instr. and Meth. B
(2006) - et al.
Appl. Radiat. Isotopes
(2007) - et al.
Nucl. Instr. and Meth. B
(2001) - et al.
Nucl. Instr. and Meth. B
(2008) - et al.
Nucl. Instr. and Meth. B
(2008) - et al.
Cancer Biother. Radiopharm.
(2000) - IAEA-Vienna, CRP Nuclear Data for the Production of Therapeutic Radioisotopes,...
Med. Phys.
Acta Oncol.
Radiochim. Acta
Cited by (63)
Evaluated and recommended cross section data for production of radionuclides with emerging interest in nuclear medicine imaging. Part 2: Single photon emission computed tomography (SPECT)
2023, Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and AtomsInvestigation of (d, 3n) reaction cross section using theoretical nuclear codes calculations on some nuclear materials
2022, Applied Radiation and IsotopesActivation cross sections of deuteron-induced reactions on praseodymium up to 24 MeV
2021, Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and AtomsAdditional excitation functions for radionuclides obtained by deuteron irradiation of Ta up to 50 MeV
2020, Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and AtomsThe empirical cross section behavior of (d, 3n) reaction for 20±1.5 MeV energy
2020, Applied Radiation and IsotopesDeuteron induced reactions on tellurium: An alternative for production of <sup>123</sup>I?
2020, Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and AtomsCitation Excerpt :As we discussed in detail for the first time in [9] the classical model codes have large difficulties in predicting accurately the values, and even energy, of the maximal cross section for deuteron induced reactions. To see what are the performances of the recent versions of ALICE-D and Empire-D specifically developed to better describe deuteron induced reactions in Obninsk (see [9]) new calculations were performed and are compared to the experimental results in this study. In recent years most advances in generally available codes have been made through the TALYS system.