67Ga Reaction Research Articles

Cross-section measurements for 68Zn(p,2p)67Cu and 68Zn(p,2n)67Ga reactions using a newly developed separation method for the superposed gamma-ray spectra

We have developed a new analytical peak separation analysis for superposed gamma-ray peaks on ^{67}Cu and ^{67}Ga to measure the ^{68}Zn(p,2p)^{67}Cu and ^{68}Zn(p,2n)^{67}Ga reactions, unlike in most previous works that were employing a radiochemical separation to measure them. Based on the nuclear data such as the gamma-ray intensity and the half-life for each nuclide, we may develop a new analytical method that enables us to estimate the respective counts arising from each nuclide, thereby obtaining the nuclear reactions. The newly developed analytical method can universally be applied to separate the superposed gamma-ray spectra of any two nuclides, especially superior in separating the nuclides with different half-lives. In comparison with the data in the literature, the two reactions in the present work are in good agreement with those of some previous works. In addition, we compared the present ^{68}Zn(p,2n)^{67}Ga reaction without the peak separation to the data in the literature without the chemical separation, and find that a good agreement is evident, enhancing the reliability of the ^{68}Zn(p,x)^{65}Zn and ^{68}Zn(p,3n)^{66}Ga reactions, which are further measured in the present work

First results from the 63Cu(α,γ)67Ga reaction study for nuclear astrophysics purposes

The 63Cu(α,γ)67Ga reaction cross-section was measured in the energy range between 5 and 9 MeV, which is relevant to p-process nucleosynthesis. The experiment was conducted at the Dynamitron Tandem Laboratory, of the Ruhr-University Bochum in Germany, by applying the 4π γ-summing method, using a 12"×12" NaI(Tl) single crystal scintillator. The preliminary results are compared with previous measurements and theoretical TALYS calculations as well.

Study of Reaction Mechanisms in α + 69Ga reaction at ≈10 – 50 MeV

The excitation functions of 69Ga(α, n)72As, 69Ga(α, 2n)71As, 69Ga(α, 3n)70As, 69Ga(α, x)69Ge, 69Ga(α, x)68Ga and 69Ga(α, x)67Ga reactions produced in the interaction of α-projectile with 69Ga-target were studied at ≈ 10-50 MeV. The produced nuclei were different isotopes of As, Ge, and Ga, some of which have important medical applications. The theoretical model predictions were based on the statistical code COMPLETE, and the predicted results were compared and discussed with existing experimental data. Good agreement between the theoretical predictions and experimental results were obtained. Pearson's relational statistics showed moderate to strong positive correlations between the theoretically predicted and experimentally measured reaction cross-sections. Furthermore, the present investigation revealed significant pre-compound contributions in the studied energy range. Therefore, it is important to consider the admixture of pre-equilibrium and equilibrium modes of reactions when predicting the reaction cross-sections.

Cyclotron-based production of 68Ga, [68Ga]GaCl3, and [68Ga]Ga-PSMA-11 from a liquid target

PurposeTo optimize the direct production of 68Ga on a cyclotron, via the 68Zn(p,n)68Ga reaction using a liquid cyclotron target. We Investigated the yield of cyclotron-produced 68Ga, extraction of [68Ga]GaCl3 and subsequent [68Ga]Ga-PSMA-11 labeling using an automated synthesis module.MethodsIrradiations of a 1.0 M solution of [68Zn]Zn(NO3)2 in dilute (0.2–0.3 M) HNO3 were conducted using GE PETtrace cyclotrons and GE 68Ga liquid targets. The proton beam energy was degraded to a nominal 14.3 MeV to minimize the co-production of 67Ga through the 68Zn(p,2n)67Ga reaction without unduly compromising 68Ga yields. We also evaluated the effects of varying beam times (50–75 min) and beam currents (27–40 μA). Crude 68Ga production was measured. The extraction of [68Ga]GaCl3 was performed using a 2 column solid phase method on the GE FASTlab Developer platform. Extracted [68Ga]GaCl3 was used to label [68Ga]Ga-PSMA-11 that was intended for clinical use.ResultsThe decay corrected yield of 68Ga at EOB was typically > 3.7 GBq (100 mCi) for a 60 min beam, with irradiations of [68Zn]Zn(NO3)2 at 0.3 M HNO3. Target/chemistry performance was more consistent when compared with 0.2 M HNO3. Radionuclidic purity of 68Ga was typically > 99.8% at EOB and met the requirements specified in the European Pharmacopoeia (< 2% combined 66/67Ga) for a practical clinical product shelf-life. The activity yield of [68Ga]GaCl3 was typically > 50% (~ 1.85 GBq, 50 mCi); yields improved as processes were optimized. Labeling yields for [68Ga]Ga-PSMA-11 were near quantitative (~ 1.67 GBq, 45 mCi) at EOS. Cyclotron produced [68Ga]Ga-PSMA-11 underwent full quality control, stability and sterility testing, and was implemented for human use at the University of Michigan as an Investigational New Drug through the US FDA and also at the Royal Prince Alfred Hospital (RPA).ConclusionDirect cyclotron irradiation of a liquid target provides clinically relevant quantities of [68Ga]Ga-PSMA-11 and is a viable alternative to traditional 68Ge/68Ga generators.

Excitation function calculations in proton-induced nuclear reactions on Zn and Cu upto 80 MeV

Nuclear reaction model codes like the EMPIRE-3.2, the ALICE-1991 and the TALYS-1.9 have been used to calculate the excitation functions of 63Cu(p,n)63Zn, 65Cu(p,n)65Zn, 66Zn(p,n)66Ga, 67Zn(p,n)67Ga, 67Zn(p,2n)66Ga, 68Zn(p,n)68Ga and 68Zn(p,2n)67Ga reactions for incident proton energy range of 1–80 MeV. These codes compute reaction cross section using the direct, the compound and the pre-equilibrium (PEQ) processes as major nuclear reaction mechanisms. The computed results have been analyzed and compared with the available experimentally measured data and with the evaluated nuclear data files. Good agreements have been found between theoretically calculated and measured data.

Measurement of cross sections for proton-induced reactions on natural Zn

We present the cross sections for the natZn(p,x)67Cu and natZn(p,x)67Ga reactions within a proton energy range of 47.5–99.2 MeV. We efficiently separated the overlapping gamma-ray spectra of the two isotopes 67Cu and 67Ga, using an analytical method without radiochemical separation. The present data were compared with previous data from the literature, typically obtained by radiochemical separation before measuring the gamma-ray spectra of the two isotopes. Our results for the two isotopes generally showed greater or smaller values than those reported in the literature, except for some data concerning partial energy ranges, which were in agreement with the literature data. The present data were also compared with the TENDL-2017 library based on the TALYS code.

311. Preliminary results of the production of Ga-68 with biomedical cyclotron by liquid target

Purpose The aim of this work was to evaluate the feasibility of production of 68Ga via the 68Zn(p,n)68Ga reaction by proton irradiation of enriched zinc nitrate solution using a biomedical cyclotron, an alternative method to the current production through the 68Ge/68Ga generators. Methods The target material was prepared by dissolving metallic 68Zn (enrichment of 99.26%) in HNO3 6 N and then diluting it with HNO3 0.2 N to obtain a 1.7 M solution of 68Zn(NO3)2 [1] . Using the cross-section data (EXFOR database) and the proton stopping power (SRIM software), the 68Ga saturation yield and its impurities were estimated. Irradiation tests were performed using the GE PETtrace cyclotron, located at our Institution. A liquid target was used, with a 25 μm foil of Havar® and a 250 μm foil of Niobium, employed to obtain proper selection of entrance beam energy, to degrade the energy of the beam to 12 MeV in order to minimize the production of 67Ga through the 68Zn(p,2n)67Ga reaction. The modification of the target also allowed us to improve resistance of the foil to acidity of the target material. Irradiations were carried out for 32 ± 1 min at 47 ± 2 μA. The product’s activity was measured using an activity meter calibrated with a standard of 68Ge traceable to NIST, while radionuclidic purity was evaluated by using gamma-ray spectrometry with an HPGe detector. Results The gamma-spectra of the irradiated samples showed the presence of different isotopes of Ga, Cu and Co, as predicted by the theoretical estimates. Radionuclidic purity is within the limits of EU Pharmacopeia up to 3 h after end of bombardment. Separation and recovery up to a yield of 90 ± 9% was obtained. Conclusions In summary, although optimizations and further advances are necessary, the results obtained are very promising and demonstrate the feasibility to produce sufficient activity of 68Ga in cyclotron as a competitive alternative to the 68Ge/68Ga generators.

Production of Ga-68 with a General Electric PETtrace cyclotron by liquid target

PurposeIn recent years the use of 68Ga (t1/2 = 67.84 min, β+: 88.88%) for the labelling of different PET radiopharmaceuticals has significantly increased. This work aims to evaluate the feasibility of the production of 68Ga via the 68Zn(p,n)68Ga reaction by proton irradiation of an enriched zinc solution, using a biomedical cyclotron, in order to satisfy its increasing demand. MethodsIrradiations of 1.7 Msolution of 68Zn(NO3)2 in 0.2 N HNO3 were conducted with a GE PETtrace cyclotron using a slightly modified version of the liquid target used for the production of fluorine-18. The proton beam energy was degraded to 12 MeV, in order to minimize the production of 67Ga through the68Zn(p,2n)67Ga reaction. The product’s activity was measured using a calibrated activity meter and a High Purity Germanium gamma-ray detector. ResultsThe saturation yield of68Ga amounts to (330 ± 20) MBq/µA, corresponding to a produced activity of68Ga at the EOB of (4.3 ± 0.3) GBq in a typical production run at 46 µA for 32 min. The radionuclidic purity of the68Ga in the final product, after the separation, is within the limits of the European Pharmacopoeia (>99.9%) up to 3 h after the EOB. Radiochemical separation up to a yield not lower than 75% was obtained using an automated purification module. The enriched material recovery efficiency resulted higher than 80–90%. ConclusionsIn summary, this approach provides clinically relevant amounts of68Ga by cyclotron irradiation of a liquid target, as a competitive alternative to the current production through the68Ge/68Ga generators.

Preliminary Dosimetry Study of 67Ga-AATS for Human Based on Biodistribution Data in Rats

Introduction Gallium-67 (67Ga) has been used as a radionuclide for imaging a variety of solid tumors since 1969. Since then use of various gallium-based radiotracers has been reported. Recently, 67Ga-labeled acetylacetate bis(thiosemicarbazones) (67Ga-AATS) complex with significant tumor accumulation and fast blood clearance has been employed. Materials and Methods In this study, the absorbed dose of 67Ga-AATS in each human organ was evaluated and compared with 67Ga-citrate as the most commonly used form of 67Ga in nuclear medicine. 67Ga was produced via 68Zn(p,2n)67Ga reaction at 30 MeV cyclotron. Moreover, 67Ga-AATS was produced by adding 50 µl of AATS to absolute ethanol (1 mg/ml) in a gallium-containing vial at 80-90 °C. The absorbed dose of each human organ was calculated, using RADAR method, based on biodistribution data in Wistar rats. Results According to the results, 67Ga-AATS was produced with radionuclidic and radiochemical purity higher than 99% and 93%, respectively. The highest absorbed dose was reported in the bone surface (0.401 mGy/MBq), whereas the whole-body absorbed dose was 0.092 mGy/MBq. Conclusion The absorbed dose of each human organ was comparable with the absorbed dose received by each organ after 67Ga-citrate injection. Considering this interesting finding and the significant tumor uptake, it seems that 67Ga-AATS can be used as an appropriate SPECT tracer.

Measurements of 67Ga production cross section induced by protons on natZn in the low energy range from 1.678 to 2.444 MeV

The experimental production cross section for the reaction natZn(p,x)67Ga has been measured in the energy range from 1.678 to 2.444MeV. The methodology used in this work is based on characteristic X-ray emitted after irradiation by the daughter nuclei that decays by electron capture (EC) and the use of a complementary PIXE experiment. By doing so, expressions needed to determine cross section values are simplified since experimental factors such as geometric setup and an detector efficiency are avoided. 67Ga is a radionuclide particularly suited for this method since it decays by electron capture in 100% and the subsequent characteristic X-ray emission is easily detected.Natural zinc targets were fabricated by PVD technique and afterwards their thicknesses were determined by Rutherford Backscattering Spectrometry. Cross sections measurements were carried out by using the Van de Graaff accelerator located at Faculty of Sciences, University of Chile. It was found that our data for the natZn(p,x)67Ga reaction are, in general, in good agreement when compared to existing experimental data and to those calculated ALICE/ASH nuclear code. On the other hand, values predicted by Talys-1.6 are showing systematically lower magnitudes than our measured data.

Production yields of NatZn(p,x)67Ga reaction in the energy range of 1.6 to 2.5 MeV

Production yield of the 67Ga (t½ = 78.3hr.)radionuclide was measured by the NatZn(p,x)67 Ga reaction in the energy range from 1.6 to 2.5 MeV. These results are the first reported at energies under 3 MeV. The overall uncertainty of these measurements are around 7%.

An improved internal Cu 3As-alloy cyclotron target for the production of 75Br and 77Br and separation of the by-product 67Ga from the matrix activity

The use of Cu 3As-alloy in high current irradiations in an internal target system for the production of 75Br via the 75As( 3He, 3n) 75Br reaction and 77Br via the 75A(α, 2n) 77Br process has been optimized. Radiobromine is separated from the irradiated alloy by thermochromatography and is of high chemical purity. The major radionuclidic impurity in 75Br is 76Br (5–8% at EOB). Batch yields amount to 200 mCi 75Br (EOB) and 48 mCi 77Br (EOB). A wet chemical method based on cation-exchange chromatography followed by solvent extraction was developed to separate 67Ga (formed via the 65Cu(α, 2n) 67Ga reaction) from the matrix activity. The final product is chemically pure but contains 2.3% 66Ga as radionuclidic impurity. The batch yield amounts to 9mCi 67Ga (at 100 h after EOB). The process is of interest only in combination with the production of 77Br where 67Ga is formed as a by-product.

Cyclotron production of 67Ga. Cross sections and thick-target yields for the 67Zn (p,n) and 68Zn (p,2n) reactions

Natural zinc foils were irradiated with ⩾35-MeV protons and cross sections were measured for the reactions 66Zn(p,n) 66Ga, 67Zn(p,n) 67Ga, 67Zn(p,2n) 66Ga, 68Zn(p,2n) 67Ga and 68Zn(p,3n) 66Ga. Thick-target yields as well as radiocontaminant ratios were calculated from the cross-section data. Targets were also irradiated under near production conditions and the yields were compared with calculated values. An alternative production method based upon the 67Zn(p,n) 67Ga reaction was found to provide equivalent yields to those obtained from the 68Zn(p,2n) 67Ga reaction. The possibility of using double targets is also discussed.