Universiẗat, Diss., 2004--Düsseldorf.

Techn. Hochsch., Diss., 2006--Aachen.

Introduction The Los Alamos Isotope Production Program commonly irradiates target stacks consisting of high, medium and low-energy targets in the “A-”, “B-”, and “C-slots”, respectively, with a 100MeV proton beam. The Program has recently considered the production of 57Co (t1/2 = 271.74 d, 100% EC) from 58Ni using the low-energy posi-tion of the Isotope Production Facility, down-stream of two RbCl salt targets. Initial MCNPX/ CINDER’90 studies predicted 57Co radioisotopic purities >90% depending on time allotted for decay. But these studies do not account for broadening of the proton beam’s energy distribution caused by density changes in molten, potentially boiling RbCl targets upstream of the 58Ni (see e.g., [1]). During a typical production with 230 µA average proton intensity, the RbCl targets’ temperature is expected to produce beam energy changes of several MeV and commensurate effects on the yield and purity of any radioisotope irradiated in the low-energy posi-tion of the target stack. An experiment was designed to investigate both the potential for 57Co’s large-scale production and the 2-dimensional proton beam energy distribution. Material and Methods Two aluminum targets holders were fabricated to each contain 31 58Ni discs (99.48%, Isoflex, CA), 4.76 mm (Φ) x 0.127 mm (thickness). Each foil was indexed with a unique cut pattern by EDM with a 0.254 mm brass wire to allow their position in the target to be tracked through hot cell disassembly and assay (see FIG. 1). Brass residue from EDM was removed with HNO3/HCl solution. The holders’ front windows were 2.87 and 1.37 mm thick, corresponding to predicted average incident energies of 17.9 and 24.8 MeV on the Ni [2]. Each target was irradiated with protons for 1 h with an average beam current of 218 ± 3 µA to ensure an upstream RbCl target temperature and density that would mimic routine production. Following irradiation, targets were disassembled and each disc was assayed by HPGe γ-spectroscopy. Residuals 56Co (t1/2 = 77.2 d, 100% EC) and 57Co have inversely varying measured nuclear formation cross sections between approximately 15 and 40 MeV. Results and Conclusion Distributions of 56,57,58,60Co were tracked as described in both irradiated targets. The distribution of activities matched expectations, with radioisotopes produced by proton interactions with the 58Ni target (56Co and 57Co) concentrated in the area struck by IPF’s rastered, annulus-shaped proton beam, and the distribution of radioisotopes produced by neutron-induced reactions (58Co and 60Co) relatively uniform across all irradiated foils. The potential range of such temperature variations predicted by thermal modeling (approx. ± 200 °C) corre-sponds to a density variation of nearly 0.2 g.cm−3, and a change in the average energy of protons incident on the low-energy “C-slot” of approximately 5 MeV, well-matched to the indi-rectly measured energy variation plotted in FIG. 3. No energy distribution in the plane per-pendicular to the beam axis has previously been assumed in the design of IPF targets. The effective incident energy measured by yields of 57Co and 56Co is, however, almost 5 MeV higher than those predicted using Anderson and Ziegler’s well-known formalism [2]. This discrepancy is supported by previous reports [3] and likely exacerbated compared to these reports by the large magnitude of energy degradation (from 100 MeV down to 30 MeV) in the IPF target stack. For more detailed discussion, refer to Marus et al.’s abstract, also reported at this meeting. While the experiments reported do confirm the potential for many Ci-scale yields of 57Co from months-long irradiations at the IPF, the level radioisotopic impurities 56Co and 58Co are concerning. Commercial radioisotope producers using U-150 (23 MeV) and RIC-14 (14 MeV) cyclotrons in Obninsk, Russia specify 56/58Co activities at levels <0.2% of available 57Co

Strontium-82 (t1/2 = 25.5 d) is one of the medical isotopes produced on a large scale at the Isotope Production Facility (IPF) of the Los Alamos National Laboratory (LANL), employing a high intensity 100 MeV proton beam and RbCl targets. A constant increase in the 82Sr demand over the last decade combined with an established thermal limit of molten RbCl salt targets [1,2] has challenged the IPF’s world leading production capacity in recent years and necessitated the consideration of low-melting point (39.3 °C) Rb metal targets. Metal targets are used at other facilities [3–5] and offer obvious production rate advantages due to a higher relative density of Rb target atoms and a higher expected thermal performance of molten metal. One major disadvantage is the known violent reaction of molten Rb with cooling water and the potential for facility damage following a catastrophic target failure. This represents a significant risk, given the high beam intensities used routinely at IPF. In order to assess this risk, a target failure experiment was conducted at the LANL firing site using a mockup target station. Subsequent fabrication, irradiation and processing of two prototype targets showed a target thermal performance consistent with thermal modeling predictions and yields in agreement with predictions based on IAEA recommended cross sections [6]. Target failure test: The target failure test bed (FIG. 1) was constructed to represent a near replica of the IPF target station, incorporating its most important features. One of the most vulnerable components in the assembly is the Inconel beam window (FIG. 2) which forms the only barrier between the target cooling water and the beam line vacuum. The test bed also mimicked relevant IPF operational parameters seeking to simulate the target environment during irradiation, such as typical cooling water flow velocities around the target surfaces. While the aggressive thermal effects of the beam heating could not be simulated directly, heated cooling water (45 °C) ensured that the rubidium target material remained molten during the failure test. A worst case catastrophic target failure event was initiated by uncovering an oversized predrilled pinhole (1 mm Φ) to abruptly expose the molten target material to fast flowing cooling water. Prototype target irradiations: Two prototype Rb metal target containers were fabricated by machining Inconel 625 parts and by EB welding. The target containers were filled with molten Rb metal under an inert argon atmosphere. Follow-ing appropriate QA inspections, the prototype targets were irradiated in the medium energy slot of a standard IPF target stack using beam currents up to 230 µA. After irradiation the targets were transported to the LANL hot cell facili-ty for processing and for 82Sr yield verification. During the target failure test, cooling water conductivity and pressure excursions in the target chamber were continuously monitored and recorded at a rate of 1 kHz. Video footage taken of the beam window and the pinhole area combined with the recorded data indicated an aggressive reaction between the Rb metal and the cooling water, but did not reveal a violent explosion that could seriously damage the beam window. These observations, together with thermal model predictions, provided the necessary confidence to fabricate and fill prototype targets for irradiation at production-scale beam currents. X-ray imaging of filled targets (FIG. 3) shows a need for tighter control over the target fill level. One prototype target was first subjected to lower intensity (< 150 µA) beams before the second was irradiated at production level (230 µA) beams. During irradiation, monitoring of cooling water conductivity indicated no container breach or leak and, as anticipated given the model predictions, the post irradiation target inspection showed no sign of imminent thermal failure (see FIG. 4). Subsequent chemical processing of the targets followed an established procedure that was slightly modified to accommodate the larger target mass. TABLE 1 shows that post chemistry 82Sr yields agree to within 2 % of the in-target production rates expected on the basis of IAEA recommended cross sections. The table also compares 82Sr yields from the Rb metal targets against yields routinely obtained from RbCl targets, showing an increase in yield of almost 50 %.

Introduction Sr-82 is produced for PET cardiac imaging at the Isotope Production Facility (IPF) with 100-MeV proton beams. During irradiation, the target material (RbCl, Rb) and Inconel capsule are ex-posed for extended periods to intense radiation, thermally and mechanically induced stresses, and chemicals. The structural integrity of the Inconel capsules is of crucial importance to containing the target starting materials and produced Sr-82. Unexpected failure capsules severely affects the reliability of the isotope supply chain and increases in radioactive emission and wastes, maintenance cost, and personnel radia-tion exposure. Knowledge of the structural integrity of a target before irradiation plays an important role in that defects may be identified and rejected prior to irradiation. In the cases of where a breach occurs, the location of the breach can be correlated with the inspected data. Material and Methods RbCl target failure: IPF has a successful irradiation history of RbCl targets at 230 A proton beam current since the facility commissioning in 2004. In 2013 run cycle, three targets irradiated in the medium energy B slot (35–65 MeV) [1] failed unexpectedly. The failure mode was the formation and propagation of cracks at the cor-ner radius along the edge of the target (FIGS. 1a-b). The common failure location was in the rear window relative to the beam direction and at the top of the target. These targets failed relatively early in the course of irradiation and typically after several cycles of beam loss and recovery. Possible failure mechanisms: A calculated von-Mises stress analysis at room temperature of an Inconel capsule under a static pressure load at 4 MPa shows a stress concentration at the corner radius and deformation of the window (FIG. 2). Additionally, a beam loss and recovery process causes the capsule windows to fatique especially at the corner due to a thermal and pressure cyclic loading. Furthermore, there is a thermal stress within the window due a temperature gradient resulting from nonuniform heating by the donut-shaped IPF beam [2]. Finally, Cl vapor in the void region or Rb liquid at the top of the target where the highest temperature of target material (RbCl or Rb) is expected may have contribution to a stress-corrosion cracking. An individual or a combination of these mechanisms aggrevate target failure if defects (voids, cracks, or thinning) exist. When the applied stress exceeds the ultimate tensile strength of Inconel, the target is likely to fail at these locations. Non-destructive evaluation methods: Digital radiographic images were generated using a Philips 450 x-ray source set to 150–190 keV and a Varian panel detector. Ultrasonic (UT) amplitude and time-of-flight (TOF) images were generated with a spherically-focused transducer operated at 50 MHz. Results Inconel capsule halves: Radiographic images of the front and rear parts of 7 RbCl A targets (~65-95 MeV) and 7 RbCl B targets prior to target assembly (FIG. 3). For target A halves (left two columns), there is some variation in thickness between the front and rear parts. Other than thickness variation, no other defects (inclusions, voids, cracks) was detected. For target B halves (right two columns), all rear parts exhibit thinning around their edges, whereas the front parts appear more uniform. UT TOF images were performed on 4 target A halves (155, 156, 157, and 159) and 7 target B halves (154-160). The rear window of 155A appears to thin out (~12.5%) near the rim on the right half. The front of 159A shows a similar thinning (~ 15%) near the rim on the left half. Although there is a thinning along the edges, all parts except 159A front have an average thickness within the stated specification (TABLE 1). Similarly to radiographic data, UT TOF data con-firm a thinning towards the edges of the window on most of target B parts. Only images of 155B are illustrated in FIG. 4. Significant thinning (15%) is observed on 154B (front & rear), and the rear windows of 155B, 157B, 158B, and 159B. Although there is a thinning, all parts have an average thickness within the stated specification (0.0120” ± 0.0005”) except for the rear windows of 154B and 155B. No inclusions or voids are apparent in any of the parts. RbCl filled targets: For comparison purpose, three B (130, 135, 147) and two A (137, 147) filled targets were evaluated. Radiographic data show no defects in the Inconel capsules while the RbCl pucks have numerous features (cracks, voids). The images of targets 130B and 135B illustrate the basic conditions of the RbCl pucks (FIG. 5). UT TOF images of targets 130B and 135B rear and front windows are illustrated in FIG. 6. Average thicknesses of 0.011–0.014” for both rear and front windows of all 5 targets are within the stated specification. However, there is thinning around the edge of the target 135B front window. Rb empty capsule: Radiograph of an unfilled Inconel capsule with and the fill tube is shown in FIG. 7. The predrilled 1-mm OD pinhole on the front window can be easily detected with the instrument’s detection limits of 30-μm pinhole and 5-μm crack. There is no other visible defect or thickness variation. This target was filled with Rb to characterize the reaction released Rb through the pinhole with water and its effects on equipment. Rb metal filled targets: Radiographs of two Rb metal filled targets show the front and side views of Rb distribution and fill tube (FIG. 8). Voids are visible throughout the Rb and small amount of Rb remaining in the fill tube. TOF results indicate the average thicknesses of 0.0201–0.0214” for both rear and front windows of 2 targets. Except the 2B front window, all thicknesses are within stated specification (0.020” ± 0.0005). UT TOF images for the rear and front of each target capsule are shown in FIG. 9. Moiré pat-terns are likely caused by a combination of stress arising in the manufacturing/filling process and some degree of measurement artifact. Target 1B windows exhibit uniform thickness across the bulk of the diameter, with the front window being slightly thinner overall than the rear. There is slight thinning observed near the edges on both windows. Thinning is more pronounced on the left side of the rear window than the right side of the front window. Target 2B shows a more pronounced distortion particularly on the rear window. The rear window appears to have a slightly thinner concentric region approximately one-quarter of diameter in. The front window displays good uniformity, with slight thinning along the inner edge of the left. Both targets 1B and 2B were successfully irradiated up to 230 A for 2 hours. Higher beam current and longer irradiation of Rb targets is underway. Conclusion Radiographic and ultrasonic methods were used in non-destructive evaluation of pre-assembly Inconel parts and fully assembled RbCl and Rb targets. These studies show the potential to identify defective parts and/or targets prior to irradiation, to provide useful information for improving target manufacturing process, and to enable better decision-making in managing risks of target failure. The results also have target quality assurance potential, enable comparison of target features and document data for future interpretation of target failure. The benefits of non-destructive evaluation include improved target reliability, reduced target failure rate, reduced revenue loss and increased productivity of Sr-82.

Introduction Since 2005, we produce, at academic scale in Orleans, 211At for needs of chemistry and physicians teams of Nantes in research project of alpha immunotherapy. Between 2005 and 2014, several modifications were been made on preparation of target, targetry and radiation to protect personnel. Material and Methods The first target was a molten Bi metal onto a Cu support pre-treated with acid attack. The wished thickness (up to 100 µm) was obtained by mechanical treatment of target. The target is irradiated at 32MeV alpha particle beam for around 2 hours and then delivered by road transport to users. Only a measure of radiation dose was made to evaluate target activity. The second target we have used since 2010 is a electrodeposition of Bi (thickness of around 30 µm) onto AlN backing. We used a beam of 30.5 MeV for reaction 207Bi(α,n)211At (2 h with a current intensity of 2µA). Activity has measured with a detector Ge at 687 keV (γ-branching fraction = 0.26 %) before to be delivered. For all targets, beam energy on target was around 28.7 Mev in order not to produce too much 210At. Results and Conclusion 138 productions with the first target were delivered with an estimated activity of less than 100 MBq. Difficulties with wet extraction1, low yield of radiolabelling (metallic impurities and activation of copper resulting in 66Ga and 67Ga) made necessary to change process of extraction. With support of AlN, dry extraction was used with good yield (75–80 %) and without activation of support. Until today, 46 batchs were delivered with activity of 44 ± 12 MBq/µAh. Yield activity of 211At has been almost doubled compared to first target (25MBq/µAh). The dose burden to personnel was decreased with modification of targetry (outside of blockhouse of cyclotron, in a specific line beam to radionuclide production, cf. FIG. 1). In the case of 211At production, energy of reaction is of major impact. With our versatile accelerator (range of energy in alpha between 10 and 50 MeV) and a low thickness of metal, it’s easy to reach the right energy. This radionuclide production will be continued until ARRONAX, Nantes cyclotron, could take over from us for bigger activity of 211At.

Introduction The 80kD glycoprotein transferrin (TF) and its related receptor (TFR1) play a major role in the recruitment by cancer cells of factors for their multiplication, adhesion, invasion and metastatic potential. Though primarily designed to bind iron and then be internalised into cells with its receptor, TF can also bind most transition metals such as Co, Cr, Mn, Zr, Ni, Cu, V, In & Ga. Under certain conditions TF binds Ti (IV) even more tightly than it does Fe and that this occurs at the N-lobe (as distinct from C) of apoTF. Further, under physiological conditions the species Fe(C)Ti(N)-TF may provide the route for Ti entry into cells via TFR1 (1). Thus, the radiometal PET reporter isotope 45Ti with an ‘intermediate’ (~hrs) half-life suited to tracking cell-focused biological mechanisms is an attractive option for elucidating cellular mechanisms involving TF binding and internalisation, at least in (preclinical) animal models. 45Ti (T½ = 3.08 hr; + branching ratio = 85 %; mean β+ energy = 439keV, no significant dose-conferring non-511keV γ-emissions) was produced using the reaction 45Sc(p,n)45Ti by irradiating (monoisotopic) scandium discs with an energy-degraded proton beam produced by an 18MeV isochronous medical cyclotron. Separation and purification was achieved with an hydroxylamine hydrochloride functionalised resin. Comparative microPET imaging was performed in an immunodeficient mouse model, measuring biodistributions of the radiolabels 45Ti-oxalate and 45Ti-human-TF (45Ti-h-TF), out to 6hr post-injection. Materials and Methods High purity 15mm diameter scandium disc foils (99.5%, Goodfellow, UK) each thickness 0.100 ± 0.005 mm (55 mg) were loaded into an in-house constructed solid-targetry system mounted on a 300mm external beam line utilising helium-gas and chilled water to cool the target body (2). The proton beam was degraded to 11.7 MeV using a graphite disc integrated into the graphite collimator. This energy abolishes the competing ‘contaminant’ reactions 45Sc(p,n+p)44Sc and 45Sc(p,2n)44Ti. Beam current was measured using the well documented 65Cu(p,n)65Zn reaction. Calculations showed that the chosen energy is close to the optimal primary energy (~12 MeV) for maximising the (thin-target) yield from a 0.100 mm thick target. For separation of Ti from the Sc target two methods were examined; (i) ion exchange column separation using 2000 mg AG 50W-X8 resin conditioned with 10mL 9M HCl. Disc is dissolved in 1 mL of 9M HCl, which at completion of reaction is pipetted into column. Successive 1 mL volumes of 9M HCl are added, and subsequent elutions collected. (ii) Following Gagnon et al., (3) a method employing hydroxylamine hydro-chloride functionalised resin (’hydroxamate method’) was applied, similar to its use in our hands for purification and separation of 89Zr (2) following its original description for 89Zr by Holland et al., (4). Disc dissolved in 2mL 6M HCl, then diluted to 2M. Elute through column to waste fraction 1 (w1 – see FIG. 1). Then elute 6 mL of 2M HCl through column to w2, followed by 6 mL of traceSELECT H2O to w3. Finally, elute Ti into successive 1 mL product fractions (p1, 2 etc.) using 5 mL of 1M oxalic acid. This procedure takes approximate 1 hr. 45Ti in elution vials was measured using γ-spectroscopy. Sc in the same vials was determined later using ICP-MS. Results A typical production run using a beam current of 40 μA for 60min on a 0.100mm-thick disc produced an activity of 1.83 GBq. Radionuclidic analysis of an irradiated disc using calibrated cryo-HPGe γ-spectroscopy revealed T½ = 2.97–3.19 hr (95% CI) for 45Ti, and with contaminant 44Sc < 0.19 %, with no other isotopes detected. Despite systematic adjustments to column conditions satisfactory chemical separation was not achieved using the ion exchange column method (i), despite previous reports of its success (5). Typical results of separation using the successful hydroxamate method (ii) are shown on the FIGURE 1. It is seen that significant portion of 45Ti is lost in the initial washing steps leading to waste collection. N = 4 replicate experiments showed a variation (SD) of 10 % of the mean in each elu-tion fraction. Subsequent ICP-MS of the same elutions for (cold) Sc showed approximately 80 % by mass appeared in w1 and 20 % in w2, with negligible total mass (total fraction ~1/6000) of Sc in product (p1–4) vials. However, the FIG. 1 shows that a total of only 30% of the original activity of 45Ti (corrected to EOB) is available in the product vials, with the vial of highest specific activity (p1) containing 14 %. However, using a stack of 2×0.100mm thick Sc discs as a target yields isotope of adequate specific activity with-out need for concentration, for subsequent labelling and small-animal imaging purposes. In a ‘proof-of-principle’ experiment, two groups of healthy Balb/c-nu/nu female adult mice were administered with 45Ti radiotracers. The first group (N = 3) received approximately 20 MBq IP of 45Ti-oxalate buffered to pH = 7.0, and under-went microPET/CT imaging (Super Argus PET, Sedecal, Spain) out to 6hr post-injection, plus biodistribution analysis of radioactivity by dis-section at sacrifice (6hr). The second group (N = 3) received approximately 20 MBq IP of 45Ti-h-TF and were also studied to 6hr post-injection, followed by radioactive analysis after dissection at sacrifice. Organ and tissue biodistributions of the two groups at 6hr were similar but with 45Ti-oxalate showing slightly greater affinity for bone. Biodistribution by dissection results broadly confirmed the findings from PET images. However, TLC results suggested that similarity of radiolabel biodistributions of the two groups may be due to contamination of the TF radiolabel with non-conjugated Ti at time of injection. An alternative explanation is dechelation in vivo of 45Ti from 45Ti-h-TF. Conclusion Despite significant loss of 45Ti to the waste fractions of the separation process (total 53 %, corrected to EOB), 45Ti of acceptable specific activity and high radionuclidic purity has been produced from the reaction 45Sc(p,n)45Ti, with separation and purification of the product by hydroxamate column chemistry, confirming an earlier report. Though microPET in vivo imaging using 45Ti-based radiolabels was shown to be feasible, the similarity in the results for the label 45Ti-h-TF compared with ‘raw’ 45Ti-oxalate suggests further investigations. These may include a direct comparison of in vivo 45Ti-h-TF small-animal imaging plus post-dissection biodistribution with the same procedures using 89Zr labelled h-apotransferrin (6).

Introduction To explore new questions and techniques in nuclear medicine, new isotopes with novel chemical and nuclear properties must be developed. We are interested in the small cyclotron production of new radiometals for the development of new radiopharmaceuticals (RX). In an example of RX multifunctionality, Luminescence Cell Imaging (LCI) has been combined with radio-isotopes to allow compounds that can be imaged with both optical microscopy and nuclear techniques [1]. Within this field, iridium cy-clometalates have good potential with excellent photophysical properties [2]. As well, low specific activity iridium-192 has found use in brachy-therapy as a high-intensity beta emitter [3]. Despite this, iridium radioisotopes have yet to be applied to cyclometalation chemistry, or a radiochemical isolation method developed for carrier free production on a medical cyclotron. Our goal is to demonstrate the feasibility of the production and isolation of radio-iridium, and its application to cyclometalate chemistry as a potentially interesting tool for nuclear medicine research. Materials and Methods Following literature precedent [4], natural osmium was electroplated onto a silver disc from basic media containing osmium tetroxide and sulphamic acid. The thin deposits obtained (15–20 mg cm−2) were weighed and characterized with scanning electron microscopy. Targets were irradiated using the TRIUMF TR13 cyclotron, delivering 12.5 MeV protons to the target disc. Initial bombardments were per-formed at 5 μA; gamma spectra of the targets were collected 24 hours after end of bombardment. The irradiated material was oxidized, dissolved from the target backing, and separated via anion exchange. In parallel to the isotope production work, non-radioactive iridium was used to define a chemical procedure suitable for the synthesis of model iridium cyclometalate compounds given low concentrations of radioiridium. These experiments will be performed with radioactive iridium in the next step of the research project. Results and Conclusion Proton bombardment of natural osmium yielded a range of iridium isotopes, with characteristic spectral lines corresponding to 186-190Ir, and 192Ir; no other characteristic radiation was observed. The EOB activity of each isotope was then used in thin target calculations to approximate their (p,n) cross section. Preliminary cross section measurements of the 192Os(p,n)192Ir reaction (53 ± 13 mb @ 12.5 MeV) confirm published data (52.3 ± 5.7 mb @ 12.2 MeV) [6], and provide as-yet unpublished data on the lower mass number isotopes. The progress of radioactive iridium through the radiochemical separation was tracked with a dose calibrator; the osmium complex formed was brightly coloured and could be seen retained on the column. The overall efficiency of the process is estimated at 80 %. Radioactive cyclometallation chemistry is currently under-way. The production and isolation of a range of iridium isotopes in a chemically useful form was demonstrated, and is ready to be applied to a cyclometalate model compound. Future work will investigate the production of 192Ir from enriched 192Os.

Introduction 68Ge (t½ = 270.8 d, 100% EC) is an important radionuclide for two reasons: 1) once in equilib-rium with its daughter nuclide 68Ga (t½ = 68 min, 89 % β+, 3 % 1077 keV γ), it can be used as a positron source for attenuation correction and calibration of PET/MRI scanners; and 2) it can be employed as a generator of 68Ga for radiophar-maceutical preparation. Most isotope production facilities produce it using natural gallium (60.1% 69Ga, 39.9% 71Ga, melting point: 39 °C) as target material for proton bombardment at energies > 11.5 MeV, the threshold energy for 69Ga(p,2n)68Ge [1]. A maximum cross section of ~330 mb for natGa(p,x)68Ge occurs at ~20 MeV [1], hence proton energies in this neighborhood are mandatory for large scale production. Galli-um targetry is challenging due to its low melting point and corrosivity, hence compounds such as Ga2O3 (melting point: 1900 °C) or GaxNiy alloys (melting points > 800 °C) [2], have been used as target compounds [3,4,5]. The separation chem-istry technique employed by large-scale produc-tion facilities is liquid-liquid extraction using CCl4 [6,7]. In this work, two simple methods for GaxNiy alloy preparation are presented as well as a simple germanium separation procedure using a commercially available extraction resin. Material and Methods GaxNiy alloys were prepared by two methods (A,B). A) electrodeposition over 1.3 cm2 of a gold disk substrate. Ga2O3 and NiSO4.6H2O were dis-solved in a mixture of (27%) H2SO4 and NH4OH at pH 1.5 in a 3:2 mass ratio so that the Ga:Ni molar ratio was 4:1. The solution was then transferred to a 15 mL plating cell, in which a current of 29 mA/cm2 was applied with a platinum anode at 1 cm from the gold surface. B) Ga pellets were fused together with Ni powder at different Ga:Ni molar ratios using an induction furnace (EIA Power Cube 45/900). The resulting alloy pellets were then rolled to foils using a jeweler’s mill pressed between Nb foils to avoid contamination. Target irradiations were performed on a GE PETtrace at 16 MeV protons. The electroplated alloys were mounted on a custom-made solid target irradiation system with direct water-jet cooling applied to the backside of the gold disk. The alloy foils were placed on top of in a 1.2 cm diameter, 406 μm deep pocket made of Nb and sealed against a 51 μm Nb foil using a teflon O-ring. The alloys were in direct contact with the Nb foil to allow thermal conduction. At the rear of the Nb pocket is a water-cooling stream to transfer heat convectively during irradiation. Ge separation was achieved based on the difference in distribution coefficients between Ge, Ga, Zn, Cu, Ni and Co at different HNO3 molarities in DGA resin (Triskem International). Initial tests on the resin were performed after two pilot irradiations on natural gallium (a,b). a) 16 MeV protons were directed downward on an external beam-line (−30 °) onto 640 mg of molten elemental natGa pooled on a water-cooled niobium support. b) 330 mg natGa pellet was melted in the same Nb pocket well used with the alloys and was also sealed against a 51 μm Nb foil. The irradiated gallium was left to decay for 2 weeks and then was dissolved in 6 mL of concentrated HNO3. The solution was then passed through 200 mg of DGA resin packed in a 5 mm diameter column at a flow rate of 1.1 mL/min. A separation profile for Ge, Ga and Zn was obtained by collecting 0.2–1.0 mL fractions, which were analyzed by gamma ray spectroscopy on a HPGe detector. Two thick NiGa4 foils have been irradiated, one for 69Ge production and for radiocobalt, from 58Ni(p,α), separation quantification; and the other one for 68Ge production with the idea of preparing a mini-generator (< 13 MBq) of 68Ga for local use in phantom imaging work and animal studies. Results and Conclusion A) Each electroplating batch consisted of 66.5 ± 2.9 mg of Ga2O3 mixed with 44.9 ± 3.6 mg of NiSO4.6H2O (n = 9) in the 15 mL plating cell. Higher concentrations resulted in inefficient electroplating yields due to precipitation. 66 ± 6 % of the total Ga+Ni mass in solution, that is 39.5 ± 3.3 mg of Ga-Ni was deposited after 3 d. Three plating batches over one disk resulted in a maximum target thickness of 86.7 mg/cm2. A fourth batch did not add any significant amount of alloy and salt precipitation became a problem. The electroplated surface looked homogeneous at 10× magnification on a microscope and the targets were able to withstand up to 30 μA without presenting any dark spots. B) Alloys with Ga:Ni molar ratios of 1.0, 2.0, 2.9, 3.7 and 5.2 were fused by induction heating. TABLE 1 summarizes the results from manipulating these foils. These alloys were analyzed by X-ray fluorescence using a 109Cd excitation source quantifying the x-rays peaks: 9.26 keV for Ga and 7.48 keV for Ni. A linear relationship between the ratio of count rates of these two peaks to the alloy Ga:Ni molar ratio was found and employed for the characterization of the electroplated Ga-Ni layers. Results from the irradiations over natGa on Nb supports are presented in TABLE 2. TABLE 3 presents the results from irradiating two thick NiGa4 foils made by induction heating. Figure 1 contains the separation profile with DGA. 91% of the 68Ge is eluted in 2 mL of de-ionized water. We developed two simple methods for NiGa4 alloy manufacture. With a melting point > 800 °C and 80% presence of natGa, it is a more convenient target for 68Ge production compared to Ga encapsulated in Nb. The separation method based on the extraction resin DGA yields similar results as the liquid-liquid extraction method mentioned in [6,7], but we believe this is a more convenient method since it only requires a single trap-and-release step and not many extraction steps.

Introduction High starting radioactivity is usually advantageous for producing radiopharmaceuticals with high specific radioactivity. However, the [11C]CH4 yields from N2-H2 gas target fall short from theoretical amounts, as calculated from the cross section for the well-known 14N(p,α)11C nuclear reaction1. The beneficial effect of increased target chamber temperature on [11C]CH4 yields has recently been brought forward by us2 and others3. In addition to the temperature effect, our attention has also been on the hydrogen content factor. This study intends to examine the N2-H2 target performance in a substantially larger target chamber and at higher temperatures than our setup before and compare the results to the existing data. Materials and Methods Aluminium bodied custom design target chamber is used in fixed 17 MeV proton beam irradiations. Target chamber is equipped with heating elements and cooling circuit for temperature control. In addition to the target chamber body temperature, the target gas loading pressure and irradiation current can be varied. The irradiation product is collected into an ad-sorbent trap that was immersed in a liquid argon cooling bath within a dose calibrator. Results and Conclusion Pursued data will show [11C]CH4 saturation yields (Ysat [GBq/µA]) at different irradiation and target parameters.