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.     

Experimental study and nuclear model calculations on the 192Os(p,n)192Ir reaction: Comparison of reactor and cyclotron production of the therapeutic radionuclide 192Ir.

In a search for an alternative route of production of the important therapeutic radionuclide (192)Ir (T(1/2)=78.83 d), the excitation function of the reaction (192)Os(p,n)(192)Ir was investigated from its threshold up to 20 MeV. Thin samples of enriched (192)Os were obtained by electrodeposition on Ni, and the conventional stacked-foil technique was used for cross section measurements. The experimental data were compared with the results of theoretical calculations using the codes EMPIRE-II and ALICE-IPPE. Good agreement was found with EMPIRE-II, but slightly less with the ALICE-IPPE calculations. The theoretical thick target yield of (192)Ir over the energy range E(p)=16-->8 MeV amounts to only 0.16MBq/muA.h. A comparison of the reactor and cyclotron production methods is given. In terms of yield and radionuclidic purity of (192)Ir the reactor method appears to be superior; the only advantage of the cyclotron method could be the higher specific activity of the product.     

Radiochemical determination of cross sections of α-particle induced reactions on 192Os for the production of the therapeutic radionuclide 193mPt

For determination of cross sections of α-particle induced reactions on 99.65% enriched ¹⁹²Os, the methods for electrolytic preparation of thin samples and radiochemical separation of radioplatinum were optimized. The excitation functions of the ¹⁹²Os(α,n)^195mPt and ¹⁹²Os(α,3n) ^193mPt reactions were measured from 20 to 39 MeV. The cross section of the latter reaction reaches a maximum value of about 1.5 b at an energy around 36 MeV. The results of nuclear model calculations using the codes TALYS and STAPRE agreed well with the measured data. The optimum energy range for the production of no-carrier-added ^193mPt (T_1/2=4.33 d) was found to be E_α=40→30 MeV. The thick target yield amounts to 10 MBq/μA h and a possible batch yield of 2 GBq should be sufficient for Auger electron therapy on a wide scale.     

Study of the 192Os(d,2n) reaction for production of the therapeutic radionuclide 192Ir in no-carrier added form.

In the frame of an IAEA coordinated research project (CRP) on nuclear data for production of therapeutic radionuclides, the production of 192Ir via deuteron-induced reactions on enriched 192Os was investigated up to 21 MeV deuteron energy. Cross sections were measured using the conventional stacked-foil irradiation technique and high-resolution gamma-ray spectroscopy of the activation products. No earlier experimental data were found in the literature. The excitation functions of the 192Os(d,2n)192m1+gIr and 192Os(d,p)193Os reactions were compared with the results of nuclear model calculations using the standard and presently upgraded versions (D-version) of ALICE-IPPE, EMPIRE-II and GNASH codes, while for the (d,2n) channel the GNASH and EMPIRE-II codes reproduced the data in an acceptable way; in both cases for the (d,p) reaction the very large discrepancy observed between the experimental data and standard codes results is vanishing when the upgraded versions of ALICE and EMPIRE-II are used. A comparison of the reactor and cyclotron production routes of 192Ir is given.     

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.     

(3)He-particle-induced reactions on (nat)Sb for production of (124)I.

Excitation functions of the reactions (nat)Sb((3)He,xn)(124,123,121)I were measured from their respective thresholds up to 35 MeV, with particular emphasis on data for the production of the medically important radionuclide (124)I. The conventional stacked-foil technique was used. From the experimental data the theoretical yields of the three investigated radionuclides were calculated. The yield of (124)I over the energy range E9(30He) = 35 --> 13 MeV amounts to 0.95 MBq/microA h. The radionuclidic impurities are discussed. A comparison of (3)He- and alpha-particle-induced reactions on antimony for production of (124)I is given. The alpha-particle-induced reaction on enriched (121)Sb and the (3)He-particle-induced reaction on enriched (123)Sb would lead to comparable (124)I yields, but the level of impurities in the latter case would be somewhat higher.     

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.     

Remote control production of an aqueous solution of no-carrier-added 34mCl- via the 32S(alpha,pn) nuclear reaction.

A remote system was established for the production of a biologically important radionuclide, chlorine-34m (32.0min, beta(+) 53%, IT 47%). The (32)S(alpha,pn)(34m)Cl reaction on elemental sulfur of natural isotopic composition was adopted for the production method. The target sulfur was melted by heating in the target chamber and then irradiated with 65MeV alpha particles (58.2MeV on target) at 3 microA for 30min. Generated (34m)Cl was extracted remotely with hot water from the molten sulfur in the target chamber. Within 20min, [(34m)Cl]chloride was obtained as a 10+/-3mL aqueous solution at a yield of 450 +/- 90 MBq, which corresponds to a recovery efficiency of 79 +/- 17% (n = 5). Both radionuclidic and radiochemical purities were more than 99% with a specific activity of 1.1GBq/ micromol. Non-radioactive impurities in the solution were identified as F(-), Cl(-), NO(3)(-), SO(4)(2-); other unknown ions were also present.     

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.     

A new,semi-automated system for the micro-scale synthesis of [195mPt]cisplatin suitable for clinical studies

A new, semi-automated system for the microscale synthesis of [^195mPt]cisplatin has been developed. Radiochemical yields of up to 70% of pure [^195mPt]cisplatin can be obtained routinely e.g. 555–629 MBq (15–17 mCi) from 925 MBq (25 mCi) of [^195mPt]Pt metal. Chemical losses during synthesis, and radiation exposure of personnel, have been minimized. These increased yields are the consequence of the elimination of most transfers, and enhanced yields at most steps: ammination losses decreased from 27 to 7%, and at the diiodo- to di-acquo- conversion, from 34 to 11%. The versatility of such a system is discussed.     

Cross-section measurements of the nuclear reactions Zn(d,x)Cu, Zn(d,α)Cu and Zn(p,αn)Cu for production of Cu and technical developments for small-scale production of Cu via the Zn(p,α)Cu process

The radionuclides 64Cu (T1/2=12.7h) and 67Cu (T1/2=61.9h) are useful in internal therapy. In connection with production of 64Cu, excitation functions of the reactions natZn(d,x)64Cu, 66Zn(d,alpha)64Cu and 68Zn(p,alphan)64Cu were measured radiochemically using the stacked-foil technique. From the measured data, the thick target yields of 64Cu were calculated and compared with experimental data available in the literature. The three investigated processes are discussed in comparison to the commonly used 64Ni(p,n)64Cu reaction for the production of 64Cu. As regards 67Cu production, the technical feasibility of the 70Zn(p,alpha)67Cu process was investigated. An electroplated isotopically enriched 70Zn target was developed which can withstand slanting beams of 20MeV protons of currents up to 20 microA. Methods for chemical separation of 67Cu and efficient recovery of the enriched target material were worked out. The method is suitable only for small-scale production of 67Cu.     

Decay of tungsten-189.

We studied the decay of 189W as produced via the 192Os[n,alpha]189W reaction on a 99.9% isotopically enriched 192Os target. The irradiations were performed at the intense neutron beam facility at Cyclotron Research Center, Université Catholique Louvain-la-Neuve (CRC-UCL) (Belgium), where fast neutrons [En approximately 20 MeV, phi(n) = (4.8 +/- 0.3)10(11) ns(-1) cm(-2)] were generated by stopping 50 MeV deuterons on a thick Be target. The half-life of 189W was determined to be 9.3 +/- 0.3min, compared to 10.8 +/- 0.2min obtained from the 188W[n,gamma]189W reaction. The energies of the two predominant gamma-rays of 189W, 260.4 +/- 1.3 and 421.7 +/- 1.4 keV were in good agreement with that from the [n,gamma] reaction, however, the relative intensities of the two gamma-rays were not consistent. From the [n,gamma] reaction, the relative intensities of the 260 and 421 keV gamma-rays were 97 to 100, whereas from the [n,alpha] reaction the relative intensities were 100 to 77, respectively. Assuming a cross-section ratio of 20 +/- 5 for [n,p3n] to [n,alpha] reactions, a cross-section of 0.5 +/- 0.2 mb was suggested for the 192Os[n,alpha]189W reaction, and the absolute intensity of the 260 keV gamma-ray was estimated to be approximately 50%.     

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.     

Excitation functions of 125Te(p, xn)-reactions from their respective thresholds up to 100 MeV with special reference to the production of 124I.

Excitation functions of the nuclear reactions 125Te(p, xn) (119,120m, 120g, 121,122,123,124,125)I were measured for the first time from their respective thresholds up to 100 MeV using the stacked-foil technique. Thin samples were prepared by electrolytic deposition of 98.3% enriched 125Te on Ti-backing. In addition to experimental studies, excitation functions were calculated by the modified hybrid model code ALICE-IPPE. The experimental and theoretical data generally showed good agreement. From the measured cross section data, integral yields of (123,124,125)I were calculated. The energy range Ep 21 --> 15 MeV appears to be very suitable for the production of the medically interesting radionuclide 124I (T(1/2) = 4.18 d; I(beta)+ = 25%). The thick target yield of 124I amounts to 81 MBq/microA h and the level of 125I-impurity to 0.9%. The 125Te(p,2n)124I reaction gives 124I yield about four times higher than the commonly used 124Te(p,n)124I and 124Te(d,2n)124I reactions. The proposed production energy range is too high for small cyclotrons but large quantities of 124I can be produced with medium-sized commercial machines.     

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-section measurement of the 169 Tm p,n reaction for the production of the therapeutic radionuclide 169 Yb and comparison with its reactor-based generation.

The radionuclide (169)Yb (T(1/2)=32.0 d) is potentially important for internal radiotherapy. It is generally produced using a nuclear reactor. In this work the possibility of its production at a cyclotron was investigated. A detailed determination of the excitation function of the (169)Tm(p,n)(169)Yb reaction was done over the proton energy range up to 45 MeV using the stacked-foil technique and high-resolution gamma-ray spectrometry. The integral yield of (169)Yb was calculated. Over the optimum energy range E(P)=16-->7 MeV the yield amounts to 1.5 MBq/micro Ah and is thus rather low. A comparison of this production route with the established (168)Yb(n,gamma)(169)Yb reaction at a nuclear reactor is given. The (169)Yb yield via the reactor route is by several orders of magnitude higher than by the cyclotron method. The latter procedure, however, leads to "no-carrier-added" product.     

Excitation functions of 124Te(d,xn)124,125I reactions from threshold up to 14 MeV: comparative evaluation of nuclear routes for the production of 124I.

Excitation functions of the nuclear reactions 124Te(d,xn)124-125I were measured from their respective thresholds up to 14.0 MeV via the stacked-foil technique. Thin samples were prepared by electrolytic deposition of 99.8% enriched 124Te on Ti-backing. The excitation function of the 124Te(d,n)125I reaction was measured for the first time. The present data for the 124Te(d,2n)124I reaction are by an order of magnitude higher than the literature experimental data but are in good agreement with the results of a hybrid model calculation. From the measured cross sections, integral yields of 124,125I were calculated. The energy range Ed = 14 --> 10 MeV appears to be the best compromise between 124I-yield and 1251-impurity. The calculated 124I-yield amounts to 17.5 MBq/microA h and the 125I-impurity to 1.7%. A critical evaluation of the three nuclear routes for the production of 124I, viz. 124Te(d,2n)-, 124Te(p,n)- and 125Te(p,2n)-processes, is given. The reaction studied in this work proved to be least suitable. The 124Te(p,n)-reaction gives 124I of the highest radionuclidic purity, and a small-sized cyclotron is adequate for production purposes. The 125Te(p,2n)-reaction is more suitable at a medium-sized cyclotron: the yield of 124I is four times higher than in the other two reactions but the level of 0.9% 125I-impurity is relatively high.     

Some optimisation studies relevant to the production of high-purity 124I and 120gI at a small-sized cyclotron.

Optimisation experiments on the production of the positron emitting radionuclides 124I(T(1/2) = 4.18d) and (120g)I (T(1/2) = 1.35 h) were carried out. The TeO(2)-target technology and dry distillation method of radioiodine separation were used. The removal of radioiodine was studied as a function of time and the loss of TeO(2) from the target as a function of oven temperature and time of distillation. A distillation time of 15 min at 750 degrees C was found to be ideal. Using a very pure source and comparing the intensities of the annihilation and X-ray radiation, a value of 22.0 +/- 0.5% for the beta(+) branching in 124I was obtained. Production of 124I was done using 200 mg/cm(2) targets of 99.8% enriched 124TeO(2) on Pt-backing, 16 MeV proton beam intensities of 10 microA, and irradiation times of about 8 h. The average yield of 124I at EOB was 470 MBq(12.7 mCi). At the time of application (about 70 h after EOB) the radionuclidic impurity 123I (T(1/2) = 13.2 h) was <1%. The levels of other impurities were negligible (126I < 0.0001%;125I = 0.01%). Special care was taken to determine the 125I impurity. For the production of (120g)I only a thin 30 mg target (on 0.5 cm(2) area) of 99.9% enriched 120TeO(2) was available. Irradiations were done with 16 MeV protons for 80 min at beam currents of 7 microA. The 120gI yield achieved at EOB was 700 MBq(19 mCi), and the only impurity detected was the isomeric state 120 mI(T(1/2) = 53 min) at a level of 4.0%. The radiochemical purity of both 124I and 120gI was checked via HPLC and TLC. The radioiodine collected in 0.02 M NaOH solution existed >98% as iodide. The amount of inactive Te found in radioiodine was <1 microg. High purity 124I and 120gI can thus be advantageously produced on a medium scale using the low-energy (p,n) reaction at a small-sized cyclotron.     

Production of [17F]CH3F (t1/2=65 s), an improved PET tracer for rCBF measurement.

Production of 17F (t1/2=65 s) in the form of [17F] F2 has been achieved using both the 20Ne(p,alpha)17F and 16O(d,n)17F reactions with 11 MeV protons and 6 MeV deuterons, respectively. Yields have proven suitable for subsequent radiosynthesis of the blood flow tracer, [17F]CH3F (>60 mCi in saline), currently in use for fast repetition human studies of regional cerebral blood flow with positron emission tomography. Thick target yields of 15 mCi /microA for protons and 44 mCi/microA for deuterons have been measured for [17F]F2.     

Experimental studies on excitation functions of the proton-induced activation reactions on yttrium.

Proton-induced activation cross-sections were measured for the (89)Y(p,x)(89,88,86)Zr, (89)Y(p,x)(88,87,87 m,86)Y, (89)Y(p,x)(85,83,82)Sr and (89)Y(p,x)(84,83)Rb reactions by a stacked foil technique in the energy range 15-80 MeV which was covered by two separate measurements for 15-50 and 32-80 MeV energy range with 50 and 80 MeV incident protons. The differences between the results of two irradiations were found within 6% in the overlapping energy regions. The production yields for the long-lived products like (88)Zr, and (88)Y are significantly larger than that of (nat)Mo+p, (nat)Nb+p and (nat)Zr+p processes. The productions of the medical isotopes, (85)Sr and (83)Sr are also effective by Y+p process using an 80 MeV beam. Thick target integral yields were also deduced using the measured cross-sections. The (87)Y, (88)Y, (88)Zr and (89)Zr radionuclides have suitable yields and decay characteristics important for thin-layer activation (TLA) analysis.