Excitation functions of (alpha,xn) reactions on (nat)Rb and (nat)Sr from threshold up to 26 MeV: possibility of production of (87)Y, (88)Y and (89)Zr.

Excitation functions were measured by the stacked-foil technique for (nat)Rb(alpha,xn)(87m,87m+g,88)Y and (nat)Sr(alpha,xn)(86,88,89)Zr reactions from their respective thresholds up to 26 MeV. The samples for irradiation were prepared by sedimentation and pellet pressing techniques. The measured data were compared with those available in the literature. From the excitation functions, integral yields of the products were calculated. The suitable energy ranges for the production of (87)Y and (88)Y via (nat)Rb(alpha,xn) processes and of (89)Zr via the (nat)Sr(alpha,xn) process are E(alpha)=26-->20 MeV, E(alpha)=26-->5 MeV and E(alpha)=20-->8.5 MeV, respectively. The respective yields amount to 8.2, 0.08 and 0.9 MBq/microA h. Production of (88)Y is feasible if a waiting time of about 2 months is allowed to let the impurities decay out. Also, (87)Y can be produced with a relatively low impurity of (88)Y. The yields of both (88)Y and (87)Y via the present routes are, however, appreciably lower than those via the (nat)Sr(p,xn) processes. There is a possibility to produce (89)Zr via the alpha-particle irradiation of (nat)Sr. The yield is rather low but would be considerably increased if enriched (86)Sr would be used as target material. The radionuclidic impurity levels in all the three products are discussed.     

Experimental studies of the deuteron-induced activation cross-sections on natAg.

Excitation functions were measured for the (nat)Ag(d,x)(105,106m,110m)Ag, (nat)Ag(d,x)(107,109)Cd and (27)Al(d,x)(24)Na reactions by the stacked-foil activation technique and high-resolution gamma-spectroscopy over the energy range 0.44-40 MeV. The thick target integral yields were deduced using the measured cross-sections. No experimental data on the (nat)Ag+d process are available in the literature above 27 MeV. The nuclides (105)Ag, (106m)Ag and (109)Cd produced with deuteron induced activation of natural silver have suitable yields and decay characteristics important for thin layer activation (TLA) analysis. The cross-section for the production of (107)Cd and (109)Cd is significantly large. Therefore, the Ag+d process can be an efficient route for the production of isotope with a medium energy accelerator. The results of the model calculation using the TALYS code are not consistent with the present data. A large shift in the incident energy is found in TALYS calculations.     

Comments on the feasibility of 61Cu production by proton irradiation of (nat)Zn on a medical cyclotron.

Feasibility of 61Cu production in high radionuclidic purity form via (nat)Zn(p,x) 61Cu nuclear process is discussed. Based on the experimentally available cross-sections of the (nat)Zn(p,x) 61Cu, (nat)Zn(p,x) 60Cu and (nat)Zn(p,x) 64Cu nuclear processes the usefulness of the (nat)Zn(p,x) 61Cu process for high-scale production is questionable in the 22 --> 12 MeV energy range.     

Cross sections of (n,p), (n,alpha) and (n,2n) reactions on some isotopes of zirconium in the neutron energy range of 10-12 MeV and integral tests of differential cross section data using a 14 MeV d(Be) neutron spectrum.

Cross sections were measured for the 90Zr(n,alpha)87mSr, 90Zr(n,2n)89m,gZr, 91Zr(n,p)91mY, 92Zr(n,p)92Y, 94Zr(n,alpha)91Sr and 96Zr(n,2n)95Zr reactions over the neutron energy range of 11.4 to 12.4 MeV and for the 94Zr(n,p)94Y reaction from 9.2 to 12.4 MeV. Nuclear model calculations were performed up to 16MeV. The statistical model incorporating precompound effects reproduces excitation functions of the three major threshold reactions, namely (n,p), (n,alpha) and (n,2n), quite well. Spectrum averaged cross sections were measured using a thick target Be(d,n) neutron field at Ed = 14 MeV. For the same neutron field averaged reaction cross sections were deduced using the excitation functions measured in this work as well as those given in the ENDF/B-VI, JEF-2, JENDL-3.2, BROND and ADL-3 data files. A comparison of the experimental and deduced integral data helped validating the differential data.     

Excitation function for 7Be production in carbon by deuteron irradiations up to 50 MeV

In order to check and complement available experimental data for production of (7)Be in deuteron irradiation of (nat)C, new measurements with incident particle energy up to 50 MeV were performed. The (7)Be content, measured with HPGe spectroscopy, allows determination of the excitation function of the (nat)C(d,x)(7)Be reactions. A comparison with experimental literature values and results from updated theoretical codes (ALICE-D, EMPIRE-D, EAF2007 and TENDL2010 on-line libraries) is discussed. Thick target yields were derived from fits to our cross-sections and integrated personnel dose was calculated for different irradiation cycles and exposure scenarios around the IFMIF facility.     

Production and separation of non-carrier-added 86Y from enriched 86Sr targets.

The metallic radionuclide (86)Y was produced by irradiation of enriched (86)SrCO(3) on a low-energy proton-only cyclotron. Irradiations up to 20 microA for 2h were performed with 11 MeV protons using a water-cooled target mounting with circulating chilled helium. Experimental thick target yields of 26.7 mCi/microA yielded 24 mCi of (86)Y in 2h of bombardment at 10 microA. The difference in solubility products between Y(OH)(3) and Sr(OH)(2) allows the separation of (86)Y from an alkaline strontium solution by using filter paper with an overall yield of 88 +/- 3%. The concentration of Sr in the final product was found to be on the order of 15 ppm when using 200mg of target material as determined by ICP-MS analysis. The reactivity of (86)Y was determined to be on the order of 1.5 +/- 0.8 Ci/micromol of DOTA. The enriched target material was recovered and converted to its original chemical form with an overall efficiency >90%.     

Cross sections for (n, 2n), (n, p) and (n, alpha) reactions on osmium isotopes in the neutron energy range of 13.5-14.8MeV.

Cross sections for (n, 2n), (n, p) and (n, alpha) reactions on the osmium isotopes were measured in the neutron energies 13.5-14.8MeV by the activation technique with the monitor reaction (93)Nb(n, 2n)(92m)Nb. Our measurements were carried out by gamma-detection using a coaxial high-purity germanium (HPGe) detector. Natural high-purity osmium powder (99.9%) was fabricated as the samples. The neutron energies were determined by the cross-section ratios for (93)Nb(n, 2n)(92m)Nb and (90)Zr(n, 2n)(89m+g)Zr reactions. The fast neutrons were produced by the T(d, n)(4)He reaction. The results obtained were compared with previous data.     

Production of no-carrier-added zirconium-89 for positron emission tomography

The production and radiochemical separation of ⁸⁹Zr from deuteron irradiation of natural yttrium targets is described. The production is optimized in order to minimize the level of the long lived ⁸⁸Zr. The yield of ⁸⁹Zr at 16 MeV incident deuteron energy is 18 ± 1.5 GBq/C (1.8 ± 0.15 mCi/μ Ah) for a target thickness of 240 mg/cm² and the contamination of ⁸⁸Zr is only 0.008% at EOB. The radiochemical separation of ⁸⁹Zr from the irradiated Y targets is by anion exchange chromatography with an overall yield of 80%. The intended use of ⁸⁹Zr is to label monoclonal antibodies (MoAbs) for tumour imaging using PET.     

Alpha-particle induced reactions on natSb and 121Sb with particular reference to the production of the medically interesting radionuclide 124I.

Excitation functions of the reactions (nat)Sb(alpha,xn)(123,124,125,126)I and (121)Sb(alpha,xn)(123,124)I were measured from their respective thresholds up to 26 MeV, with particular emphasis on data for the production of the medically important radionuclide (124)I. The conventional stacked-foil technique was used, and the samples for irradiation were prepared by a sedimentation process. The measured excitation curves were compared with the data available in the literature. From the experimental data the theoretical yields of the investigated radionuclides were calculated as a function of the alpha-particle energy. The calculated yield of (124)I from the (nat)Sb(alpha,xn)(124)I process over the energy range E(alpha) = 22-->13 MeV amounts to 1.02 MBq/microA x h and from the (121)Sb(alpha,n)(124)I reaction over the same energy range to 2.11 MBq/microA x h. The radionuclidic impurity levels are discussed. Use of (nat)Sb as target material would not lead to high-purity (124)I. Using highly enriched (121)Sb as target, production of (124)I of high radionuclidic purity is possible; the batch yield, however, is low.     

Cross section measurements for (n, 3n) reactions induced by 14.8 MeV neutrons.

The cross sections for 209Bi(n, 3n)207Bi, 191Ir(n, 3n)189Ir, 151Eu(n, 3n)149Eu and 185Re(n, 3n)183Re reactions were measured by the activation method. The experimental results were 12.1+/-1.1, 64.6+/-6.5, 2.7+/-0.4 and 66.0+/-5.6 mb at the neutron energy of 14.8+/-0.2 MeV, respectively. The neutron flux was determined by the cross section of the 27Al(n, alpha)24Na reaction. The neutron energy in these measurements was determined by the method of cross section ratios for 90Zr(n, 2n)(89m + g)Zr and 93Nb(n, 2n)92mNb reactions.     

Monte carlo simulations and experimental studies of yttrium-90 production using a 33 MeV linac.

The purpose of this research is the investigation of the 90Zr(n,p)90Y reaction as an alternative method to the traditional fission product based on the 90Sr/90Y generator. The fast neutrons necessary to activate 90Zr are generated through (p,xn) reactions during 33 MeV proton irradiation of natural tungsten or other targets. Since 90Y is a pure beta emitter, the gamma-rays from the 90Zr(n,2n)59Zr reaction were used to quantify the neutron flux incident on the 90Zr sample. Using the simulation code MCNPX (Monte Carlo N-Particle System), the angular and energy distributions of neutrons incident on the Zr target were calculated. Based on the MCNPX neutron flux predictions, the 90Y activity was determined.     

Excitation functions of 85Rb(p,xn)(85m,g,83,82,81)Sr reactions up to 100 MeV: integral tests of cross section data, comparison of production routes of 83Sr and thick target yield of 82Sr.

The beta+ emitter 83Sr (T(1/2) = 32.4 h, Ebeta+ = 1.23 MeV, Ibeta+ = 24%) is a potentially useful radionuclide for therapy planning prior to the use of the beta+ emitter 89Sr (T(1/2) = 50.5 d). In order to investigate its production possibility, cross section measurements on the 85Rb(p,xn)-reactions, leading to the formation of the isotopes (85m,g)Sr, 83Sr, 82Sr and 81Sr, were carried out using the stacked-foil technique. In a few cases, the products were separated via high-performance liquid chromatography. For 82Sr, both gamma-ray and X-ray spectrometry were applied; in other cases only gamma-ray spectrometry was used. From the measured excitation functions, the expected yields were calculated. For the energy range Ep = 37 --> 30 MeV the 83Sr yield amounts to 160 MBq/microA h and the level of the 85gSr (T(1,2) = 64.9 d) and 82Sr (T(1/2) = 25.5 d) impurities to <0.25%. In integral tests involving yield measurements radiostrontium was chemically separated and its radioactivity determined. The experimental production data agreed within 10% with those deduced from the excitation functions. The results of the 85Rb(p,3n)83Sr reaction were compared with the data on the production of 83Sr via the 82Kr(3He,2n)-process. In the energy range E3Hc = 18 --> 10 MeV the theoretical yield of 83Sr amounts to 5 MBq/microA h and the 82Sr impurity to about 0.2%. The method of choice for the production of 83Sr is thus the 85Rb(p,3n)-process, provided a 40 MeV cyclotron is available. During this study some supplementary information on the yield and purity of 82Sr was also obtained.     

Nuclear data for production of the therapeutic radionuclides 32P, 64Cu, 67Cu, 89Sr, 90Y and 153Sm via the (n,p) reaction: evaluation of excitation function and its validation via integral cross-section measurement using a 14 MeV d(Be) neutron source.

Nuclear data for production of the therapeutic radionuclides 32P, 64Cu, 67Cu, 89Sr, 90Y and 153Sm via (n,p) reactions on the target nuclei 32S, 64Zn, 67Zn, 89Y, (90)Zr and 153Eu, respectively, are discussed. The available information on each excitation function was analysed. From the recommended data set for each reaction the average integrated cross section for a standard 14 MeV d(Be) neutron field was deduced. The spectrum-averaged cross section was also measured experimentally. A comparison of the integrated value with the integral measurement served to validate the excitation function within about 15%. A fast neutron source appears to be much more effective than a fission reactor for production of the above-mentioned radionuclides in a no-carrier-added form via the (n,p) process. In particular, the possibility of production of high specific activity 153Sm is discussed.     

Yield and purity of 82Sr produced via the natRb(p,xn)82Sr process

The recently reported cross-section data for the production of ⁸²Sr via the ^natRb(p,xn)⁸²Sr process were evaluated. For the ^natRb(p,xn)⁸⁵Sr process, cross-sections were measured experimentally over the proton energy range of 25–45 MeV, a region where very few data existed. An evaluation of the recently published data on the formation of ⁸⁵Sr was then also performed. From the recommended data curves, the integral yields of the desired radionuclide ⁸²Sr and the impurity ⁸⁵Sr were calculated. Yields were also determined experimentally over several energy ranges using thick ^natRbCl targets. The experimental and calculated yields were found to be in agreement within 15%. These integral tests add confidence to the evaluated cross-section data. For the production of ⁸²Sr, an incident proton energy of 60 MeV or above is recommended; the ⁸⁵Sr impurity then corresponds to <20%.     

Measurement of excitation functions of helion-induced reactions on enriched Ru targets for production of medically important 103Pd and 101mRh and some other radionuclides.

Excitation functions were determined by the stacked-foil and induced radioactivity measurement technique for the reactions (100)Ru(alpha,n)(103)Pd, (101)Ru(alpha,2n)(103)Pd, (101)Ru((3)He,n)(103)Pd, and (102)Ru((3)He,2n)(103)Pd, producing the therapeutic radionuclide (103)Pd, and for the reactions (101)Ru((3)He,x)(101 m)Rh(Cum) and (102)Ru((3)He,x)(101 m)Rh(Cum), producing the medically interesting radionuclide (101 m)Rh. Data were also measured for the reactions (101)Ru((3)He,pn+d)(102 m,g)Rh, (102)Ru((3)He,p2n+dn+t)(102 m,g)Rh, (101)Ru((3)He,x)(101 g)Rh(Cum), (102)Ru((3)He,x)(101 g)Rh(Cum), (101)Ru((3)He,3n)(101)Pd, (102)Ru((3)He,4n)(101)Pd, (101)Ru((3)He,4n)(100)Pd, and (101)Ru((3)He,p3n+d2n+tn)(100)Rh, producing other palladium and rhodium isotopes/isomers. The energy ranges covered were up to 25 MeV for alpha-particles and up to 34 MeV for (3)He ions. The radioactivity of the radionuclide (103)Pd induced in thin metallic foils of the enriched ruthenium isotopes was measured by high-resolution X-ray spectrometry and the radioactivities of other radionuclides by gamma-ray spectrometry. The integral thick target yields of the radionuclide (103)Pd calculated from the excitation functions of the first four of the above-named reactions amount to 960, 1050, 50, and 725 kBq/microAh, respectively, at the maximum investigated energies of the incident particles. The integral thick target yields of the radionuclide (101 m)Rh amount to 16.1 and 2.9 MBq/microAh for (101)Ru and (102)Ru targets, respectively, at 34 MeV energy of incident (3)He ions. The integral yields of the other observed radionuclides were also deduced from the excitation functions of the above-mentioned respective nuclear reactions. The excitation functions and integral yields of some rare reaction products were also determined. The experimental excitation functions of some reactions are compared with the predictions of nuclear model calculations. In general, good agreement was obtained.     

Activation cross sections of the 169Tm(d,2n) reaction for production of the therapeutic radionuclide 169Yb.

Activation cross sections of deuteron induced nuclear reactions on (169)Tm were measured up to 20 MeV by using the stacked-foil technique. Special emphasis was on production of the internal radiotherapy related radionuclide (169)Yb. No earlier experimental cross-section data on deuteron induced reactions on (169)Tm were found in the literature. The experimental data were compared with the results of the nuclear model codes ALICE-IPPE and EMPIRE-II. The integral yield of the (169)Tm(d,2n)(169)Yb reaction was deduced over the optimum energy range Ed = 20-->9 MeV. At 3.8 MBq/microA.h the yield is lower than that available from the commonly used (168)Yb(n,gamma) (169)Yb reactor method but on the other hand, it is higher than the yields from the earlier investigated (169)Tm(p,n)(169)Yb and (nat)Er(alpha,x) (169)Yb reactions.     

The production of radionuclides for nuclear medicine from a compact,low-energy accelerator system

IntroductionThe field of nuclear medicine is reliant on radionuclides for medical imaging procedures and radioimmunotherapy (RIT). The recent shut-downs of key radionuclide producers have highlighted the fragility of the current radionuclide supply network, however. To ensure that nuclear medicine can continue to grow, adding new diagnostic and therapy options to healthcare, novel and reliable production methods are required. Siemens are developing a low-energy, high-current – up to 10 MeV and 1 mA respectively – accelerator. The capability of this low-cost, compact system for radionuclide production, for use in nuclear medicine procedures, has been considered.MethodologyThe production of three medically important radionuclides – ⁸⁹Zr, ⁶⁴Cu, and ¹⁰³Pd – has been considered, via the ⁸⁹Y(p,n), ⁶⁴Ni(p,n) and ¹⁰³Rh(p,n) reactions, respectively. Theoretical cross-sections were generated using TALYS and compared to experimental data available from EXFOR. Stopping power values generated by SRIM have been used, with the TALYS-generated excitation functions, to calculate potential yields and isotopic purity in different irradiation regimes.ResultsThe TALYS excitation functions were found to have a good agreement with the experimental data available from the EXFOR database. It was found that both ⁸⁹Zr and ⁶⁴Cu could be produced with high isotopic purity (over 99%), with activity yields suitable for medical diagnostics and therapy, at a proton energy of 10 MeV. At 10 MeV, the irradiation of ¹⁰³Rh produced appreciable quantities of ¹⁰²Pd, reducing the isotopic purity. A reduction in beam energy to 9.5 MeV increased the radioisotopic purity to 99% with only a small reduction in activity yield.ConclusionThis work demonstrates that the low-energy, compact accelerator system under development by Siemens would be capable of providing sufficient quantities of ⁸⁹Zr, ⁶⁴Cu, and ¹⁰³Pd for use in medical diagnostics and therapy. It is suggested that the system could be used to produce many other isotopes currently useful to nuclear medicine.     

Proton-induced activation cross-sections of the short-lived radionuclides formation on molybdenum.

Excitation functions of the natMo(p,xn)93m,93m+g,94mTc, natMo(p,pxn)90Mo and natMo(p,alphaxn)89g,89m,97Nb reactions were measured using the stacked foil activation technique up to 70 MeV. These data have been measured for the first time. The measured results were compared with the ALICE-IPPE precompound-hybrid model calculations. The calculations are in partial agreement with the measured values. Maximum production of 94mTc was found in the energy range 10-37 MeV, wherein the radionuclidic impurities for 93mTc and 93gTc are about 17% and 30%, respectively.     

Production and purification of 89Zr,a potential PET antibody label

The production of ⁸⁹Zr via the (p, n) reaction on ⁸⁹Y using 11 MeV protons was studied. Thick target yields at saturation were measured to be 100 ± 10 mCi/μA while thin target (57 mg/cm²; 11 MeV > E_p > 10 MeV) yields were found to be 43 ± 4 mCi/μA. ⁸⁹Zr was separated from the Y target by extraction into 0.03 M dibutyl phosphate in dibutyl ether. Back-extraction into 4 M HF followed by anion exchange column chromatographic purification results in high purity no carrier added ⁸⁹Zr with radiochemical yield of 84% ± 4%. Yttrium contamination is estimated to be less than the picogram level. ⁸⁹Zr-linked to proteins via DTPA may be useful as a PET antibody label.     

Half-life determination of 88Y and 89Sr.

Half-life measurements have been carried out at LNHB for 88Y using a 4pi gamma-ionisation chamber and for 89Sr using a proportional counter. The determined half-life values and associated standard uncertainties are 106.63 +/- 0.05 d for 88Y and 50.65 +/- 0.05 d for 89Sr, being consistent with relevant values reported in literature. Based on the present results and relevant literature values revised recommended half-life values and associated standard uncertainties are proposed, viz. 106.626 +/- 0.021 d for 88Y and 50.57 +/- 0.03 d for 89Sr.