Excitation functions of Se(d,xn)Br reactions: Comparative evaluation of possible routes for the production of Br at a small cyclotron

Excitation functions were measured for the first time for ⁷⁴Se(d,n)⁷⁵Br and ⁷⁴Se(d,2n)^74mBr reactions from threshold to 23 MeV. Use was made of the stacked-foil technique, and thin samples were prepared by electrolytic deposition of 31.4% enriched ⁷⁴Se on Al-backing. Differential and integral yields of ^74mBr and ⁷⁵Br were calculated from the measured excitation functions. The optimum energy range for the production of ⁷⁵Br via the ⁷⁴Se(d,n)-process was found to be E_d = 12 → 8 MeV, with ⁷⁵Br-yield amounting to 509 MBq (13.75 mCi)/μAh and the ^74mBr impurity to 78Kr(p,)⁷⁵Br and ⁷⁴Se(d,n)⁷⁵Br, suggested for the production of ⁷⁵Br at a small cyclotron is given. The (d,n) reaction gives higher yield than the (p,) process and is preferable at cyclotrons with E_d 10 MeV. In general, at a small cyclotron the achievable batch yields of ⁷⁵Br via both the processes are limited.     

Production of highly pure no-carrier added Zr for the labelling of antibodies with a positron emitter

⁸⁹Zr was produced in high amounts (130 mCi/h) via a (p,n) reaction on ⁸⁹Y. The ⁸⁹Zr-isotope was purified using a hydroxamate column. More than 95% of the Zr was eluted with 1 mL of 1 M oxalic acid. The radionuclidic purity was over 99.99%. The isolated ⁸⁹Zr quantitatively formed complexes with the chelating agent desferal at low concentrations (10–100 μM).     

Development of an automated system for the quick production of N-labeled compounds with high specific activity using anhydrous [N]NH3

An automated system was developed to synthesize ¹³N-labeled compounds with high specific activity using anhydrous [¹³N]NH₃ as a synthetic precursor. This system enabled (1) production of an aqueous solution of [¹³N]NH₃, (2) concentration and desiccation of the [¹³N]NH₃ solution, (3) reaction of anhydrous [¹³N]NH₃ with substrate, (4) purification and formulation.

By the use of this system, [¹³N]p-nitrophenyl carbamate ([¹³N]NPC) ready for i.v. injection could be obtained in 5.1±0.1 min at the yield of 3.5±0.4 GBq, specific activity 460±55 GBq/μmol, and radiochemical purity >99% (n=3) by irradiating a 10 mM ethanol solution with 18 MeV protons at 17 μA for 25 min. With special precautions, [¹³N]NPC could be obtained at the extremely high specific activity of 1800±200 GBq/μmol.     

Preparation of carrier-free yttrium-90 for medical applications by solvent extraction chromatography

The separation of carrier-free ⁹⁰Y from fission product ⁹⁰Sr by solid supported solvent extraction chromatography was investigated using Teflon grain as solid support and a di-(2-ethylhexyl) phosphoric acid (D2EHPA) extraction agent as liquid phase. The optimum separation conditions are: (1) solid support using Dupont TF800 Teflon grains, (2) using 5% D2EHPA extraction agent as liquid phase, (3) setting the flow rate at 1 cm³/min, and (4) using a column diameter of 0.5 cm which was packed with 1 g treated Teflon. After loading ⁹⁰Sr/⁹⁰Y equilibrium solution, the loaded column was washed with 0.3 N hydrochloric acid to remove ⁹⁰Sr species; subsequently, 8 N hydrochloric acid was used as an eluent to obtain a ⁹⁰Y solution. Chemical yield was about 90%; radionuclide impurity of ⁹⁰Sr in the final product was <10⁻⁶%. Consequently, the preparation of 1 mCi of ⁹⁰Y was satisfactory for radiolabeling in medical applications. A radiotracer method using ⁸⁵Sr and ⁸⁸Y was also developed to investigate separation efficiency.     

The Br(p,x)Se nuclear processes: a convenient route for the production of radioselenium tracers relevant to amino acid labelling

A possible route for the production of no-carrier-added (n.c.a.) ⁷³Se (T_1/2=7.1 h) and ⁷⁵Se (120 d) is introduced. -2-Amino-4-([⁷³Se]methyl-seleno) butanoic acid ( -[⁷³Se]selenomethionine) with an overall radiochemical yield of >40% could be prepared via a 3-step polymer-supported synthesis after successful separation of ⁷³Se from KBr targets. Excitation functions for the ^natBr(p,x) ^72,73,75Se processes were measured from threshold up to 100 MeV utilizing pellets of pressed KBr. Targets were irradiated at the NAC cyclotron with proton beams having primary energies of 40.4, 66.8 and 100.9 MeV. The calculated ⁷³Se yield (EOB) for 1 h irradiation in 1 μA of beam at the optimum proton energy range of 62→42 MeV is 81.4 MBq (2.2 mCi), and the calculated ⁷⁵Se yield (EOB) for the overall range 62 MeV→threshold for the same irradiation conditions is 0.97 MBq (0.026 mCi).     

Evaluation of novel cationic 99mTc(I)-tricarbonyl complexes as potential radiotracers for myocardial perfusion imaging

This report describes the evaluation of three cationic ^99mTc(I)–tricarbonyl complexes — [^99mTc(CO)₃(L)]⁺ (L=N-methoxyethyl-N,N-bis[2-(bis(3-ethoxypropyl)phosphino)ethyl]amine (ME-PNP), N-[15-crown-5)-2-yl]-N,N-bis[2-(bis(3-ethoxypropyl)phosphino)ethyl]amine (15C5-PNP) and N-[18-crown-6)-2-yl]-N,N-bis[2-(bis(3-ethoxypropyl)phosphino)ethyl]amine (18C6-PNP)) — as potential radiotracers for myocardial perfusion imaging. Biodistribution, imaging and metabolism studies were performed using Sprague–Dawley rats. It was found that bisphosphine ligands have a significant impact on the biodistribution characteristics and clearance kinetics of their cationic ^99mTc(I)–tricarbonyl complexes. Among the three radiotracers evaluated in this study, [^99mTc(CO)₃(15C5-PNP)]⁺ has a very high initial heart uptake and is retained in the rat myocardium for >2 h. It also shows rapid clearance from the liver and lungs. The heart/liver ratio of [^99mTc(CO)₃(15C5-PNP)]⁺ is 2.5 times better than that of ^99mTc-sestamibi at 30 min postinjection. [^99mTc(CO)₃(15C5-PNP)]⁺ is almost identical to ^99mTcN-DBODC5 with respect to heart uptake, heart/lung ratio and heart/liver ratio. Results from metabolism studies show that there is no significant metabolism for [^99mTc(CO)₃(15C5-PNP)]⁺ in the urine, but it does show a small metabolite peak (<10%) in the radio high-performance liquid chromatography chromatogram of the feces sample at 120 min postinjection. Results planar imaging studies demonstrate that [^99mTc(CO)₃(15C5-PNP)]⁺ has a much better liver clearance profile than ^99mTc-sestamibi and might give clinically useful images of the heart as early as 30 min postinjection. [^99mTc(CO)₃(15C5-PNP)]⁺ is a very promising candidate for more preclinical evaluations in various animal models.     

In Vivo localization of diglycylcysteine-bearing synthetic peptides by nuclear imaging of oxotechnetate transchelation

A phenomenon of in vivo transchelation of oxotechnetate from a complex with glucoheptonic acid to synthetic peptides bearing oxotechnetate-binding motifs and a technique for in vivo visualization of these peptides are described. Using two model peptides bearing two tandem diglycylcysteine (GGC) motifs (P1) or three GGC motifs (P2), we demonstrated that: (i) these peptides efficiently transchelated oxo-[^99mTc]technetate from a complex with glucoheptonic acid in vitro (a complex with peptides was stable at least 24 h; radiochemical purity exceeded 95% by high performance liquid chromatography); (ii) injection of peptides into the rectus femoris muscle (at 0.5-1 μmol of SH groups) followed by an intravenous injection of ^99mTc-glucoheptonate (0.25-0.5 mCi per animal) yielded visualization of the injected muscle by nuclear imaging within 1 h after injection; (iii) the experimental/control (contralateral) thigh muscle ratio was 1.80 ± 0.05 for peptide P1 and 3.0 ± 0.1 for P2; (iv) the injection of a control peptide P2 with SH groups covalently modified with N-ethylmaleimide resulted in a ratio of 1.4 ± 0.2. These findings argue for specific association of oxo-[^99mTc]technetate with free thiols within the binding motif of injected peptides in vivo. In vivo transchelation of oxo-[^99mTc]technetate may be useful for the purpose of noninvasive imaging of gene expression, i.e., when the expression product bears GGC motifs.     

An improved (99m)Tc-aprotinin kit formulation: quality control analysis of radiotracer stability and cold kit shelf life

^99mTc-aprotinin scintigraphy has been demonstrated to be a useful noninvasive imaging technique for amyloid deposits located in extraabdominal regions of patients. The aim of this study was to develop an improved aprotinin cold kit formulation, to validate the kit for long-term stability, as well as to assess the radiotracer stability by novel quality control methods. The aprotinin cold kit formulation of Trasylol, pyrophosphate (PYP)-chelated stannous reductant and an alkaline buffer, was dispensed into nitrogen-filled vials and aliquots frozen at −20°C. After 0, 1, 2, 3 and 6 months of storage, three samples were reconstituted with 750–850 MBq of ^99mTc-pertechnetate, followed by quality control analyses by paper chromatography methods at 25, 85 and 265 min postreconstitution (pr). Cation-exchange cartridge quality control methods were also investigated. The cold kits proved to be stable to long-term storage for up to 6 months, and the radiotracer was stable for at least 4 h pr. ^99mTc-aprotinin was formed at greater than 95% efficiency at all time points tested with ^99mTcO₂ present as the major impurity (1–4%) and ^99mTc-pertechnetate and ^99mTc-PYP present in trace amounts. An alternative, rapid, safe and reliable method was found in Oasis MCX–BSA-treated cartridges using saline as the eluting solution to assay for ^99mTc-aprotinin.     

Purification and activity standardisation of a Ho solution

As part of a project to use the long-lived (T_1/2=1200a) ^166mHo as reference source in its reference ionisation chamber, IRA standardised a commercially acquired solution of this nuclide using the 4πβ–γ coincidence and 4πγ (NaI) methods. The ^166mHo solution supplied by Isotope Product Laboratories was measured to have about 5% Europium impurities (3% ¹⁵⁴Eu, 0.94% ¹⁵²Eu and 0.9% ¹⁵⁵Eu). Holmium had therefore to be separated from europium, and this was carried out by means of ion-exchange chromatography. The holmium fractions were collected without europium contamination: 162 h long HPGe gamma measurements indicated no europium impurity (detection limits of 0.01% for ¹⁵²Eu and ¹⁵⁴Eu, and 0.03% for ¹⁵⁵Eu). The primary measurement of the purified ^166mHo solution with the 4π (PC) β–γ coincidence technique was carried out at three gamma energy settings: a window around the 184.4 keV peak and gamma thresholds at 121.8 and 637.3 keV. The results show very good self-consistency, and the activity concentration of the solution was evaluated to be 45.640±0.098 kBq/g (0.21% with k=1). The activity concentration of this solution was also measured by integral counting with a well-type 5″×5″ NaI(Tl) detector and efficiencies computed by Monte Carlo simulations using the GEANT code. These measurements were mutually consistent, while the resulting weighted average of the 4π NaI(Tl) method was found to agree within 0.15% with the result of the 4πβ–γ coincidence technique. An ampoule of this solution and the measured value of the concentration were submitted to the BIPM as a contribution to the Système International de Référence.     

A re-evaluation of k0 and related nuclear data for the 555.8 keV gamma-line emitted by the Rh-Rh mother–daughter pair for use in NAA

A re-evaluation is made of the k₀-factor and related nuclear data for the 555.8 keV gamma-ray of the ^104mRh-¹⁰⁴Rh mother–daughter pair that are important in neutron activation analysis (NAA). This study considers that the relevant level is also fed by the 4.34 min ^104mRh mother (with an absolute gamma-ray emission probability γ₂=0.13%) and not only, as assumed in former work, by the 42.3 s ¹⁰⁴Rh daughter isotope (with γ₃=2.0%). In view of this, generalised equations were developed for both the experimental determination and the analytical use of the k₀-factor and of the associated parameters k₀(m)/k₀(g), Q₀(m) and Q₀(g) [(m):^104mRh; (g): ¹⁰⁴Rh], requiring the introduction of the γ₂ and γ₃ data and also of the ^104mRh→¹⁰⁴Rh fractional decay factor F₂(=0.9987). The experimental determinations were based on irradiations performed in the BR1 reactor in Mol and the WWR-M reactor in Budapest. Furthermore, considering the special formation of the 555.8 keV gamma-ray, the procedure for true-coincidence correction was revised as well. All this led to the compilation and recommendation of a new set of ‘k₀-NAA’ data.     

Understanding the radiolabelling mechanism of Tc–antimony sulphide colloid

The chemistry of antimony trisulphide colloid (ATC) was examined to elucidate the radiolabelling mechanism with ^99mTcO₄⁻. Ion exchange chromatography and atomic absorption spectrophotometry techniques determined ATC to be resistant to hydrolysis in 0.1 M hydrochloric acid (HCl) at 25°C or 100°C (>97% recovery, Sb³⁺ absent). Hydrogen sulphide gas detected did not participate in the mechanism, where antimony trisulphide and ^99mTcO₄⁻ in HCl/100°C yielded 96% ^99mTc-product from a K₂S-free formulation (versus 98% when K₂S was present). ^99mTcO₄⁻ was reduced >90% by DMSA or dithiothreitol under the same conditions, identifying involvement of thiol groups. Infrared analysis of Re-ATC showed S=O bonds, indicating excess thiol groups at the colloid surface were oxidised at the expense of ^99mTcO₄⁻ reduction.     

Experimental studies and nuclear model calculations on proton-induced reactions on Se, Se and Se with particular reference to the production of the medically interesting radionuclides Br and Br

Excitation functions of the reactions ^natSe(p,x)^75,76,77,82Br, ⁷⁶Se(p,xn)^75,76Br, ⁷⁶Se(p,x)⁷⁵Se and ⁷⁷Se(p,xn)^76,77Br were measured from their respective thresholds up to 40 MeV, with particular emphasis on data for the production of the medically important radionuclides ⁷⁶Br and ⁷⁷Br. The conventional stacked-foil technique was used. The samples were prepared by a sedimentation process. Irradiations were performed using the compact cyclotron CV 28 and the injector of COSY, both at the Research Centre Jülich. In order to validate the data, nuclear model calculations were performed using the code ALICE-IPPE which is based on the preequilibrium-evaporation model. Good agreement was found between the experimental and theoretical data, except in the high-energy region where the calculated data were somewhat higher. All the measured excitation curves were compared with the data available in the literature. From the experimental data the theoretical yields of all the investigated radionuclides were calculated and plotted as a function of proton energy. The calculated yield of ⁷⁷Br from the ^natSe(p,x)⁷⁷Br process over the energy range E_p=25→15 is 72.7 MBq/μA h and from the ⁷⁷Se(p,n)⁷⁷Br reaction over E_p=15→6 MeV it is 86.2 MBq/μA h. The yield of ⁷⁶Br from the ⁷⁶Se(p,n)⁷⁶Br reaction for E_p=15→8 is 360.1 MBq/μA h and from the ⁷⁷Se(p,2n)⁷⁶Br reaction for E_p=28→18 MeV it is 879.2 MBq/μA h. The radionuclidic impurity levels are discussed.     

The effect of cyclosporine-a on labeling blood cells with radiopharmaceuticals

The effect of cyclosporine-A (CsA) on the labeling efficiencies of red blood cells with reduced ^99mTcO₄⁻; leukocytes and platelets with ¹¹¹In oxine was studied. Blood was used from rats treated with CsA (30 mg/kg body weight) for 28 consecutive days and from control rats. For ^99mTc labeling of RBCs, blood was obtained from individual rats and in vitro labeling technique was used. For leukocyte and platelet labeling, blood was pooled from 5 rats either treated with CsA or control. Leukocytes/platelets were labeled with ¹¹¹In oxine using routine techniques. The labeling efficiency for ^99mTc RBCs was 83.42 ± 0.83% (CsA treated) and 84.85 ± 0.62% (control); ¹¹¹In-oxine leukocytes was 38.5 ± 1.75% (CsA treated) and 42.5 ± 3.53% (control); and for ¹¹¹In-oxine platelets, it was 74.0 ± 2.5% (CsA treated) and 78.0 ± 1.41% (control). Comparison of the results indicate that there is no difference between the percent labeling efficiencies of ^99mTc RBCs, ¹¹¹In-oxine leukocytes, and ¹¹¹In-oxine platelets for CsA-treated and control rats. Hence, CsA does not interfere with the labeling process of blood cells with radiopharmaceuticals.     

Synthesis and evaluation of [11C]FR194921 as a nonxanthine-type PET tracer for adenosine A1 receptors in the brain

This report describes the synthesis of [¹¹C]2-(1-methyl-4-piperidinyl)-6-(2-phenylpyrazolo[1,5-a]pyridin-3-yl)-3(2H)-pyridazinone ([¹¹C]FR194921), a highly selective, nonxanthine-type adenosine A₁ receptor antagonist, used in brain imaging in rats and conscious monkeys as a potential novel PET tracer. [¹¹C]FR194921 was successfully synthesized in 19 min after [¹¹C]CH₃I formation. The radiochemical yield was 38±3%; and radioactivity was 4.1±0.4 GBq, calculated from end of synthesis; radiochemical purity was higher than 99%; and the specific radioactivity was 25.0±8.1 GBq μmol⁻¹ (n=5). In a rat experiment, the distribution of [¹¹C]FR194921 was higher in the hippocampus, striatum and cerebellum regions. This accumulation was significantly decreased by approximately 50% by pretreatment with 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), an adenosine A₁ receptor antagonist, which indicated specific binding of the radioligand to adenosine A₁ receptors. In conscious monkey PET experiments, [¹¹C]FR194921 accumulated in several regions of the brain, especially in the occipital cortex, thalamus and striatum. These results suggest that [¹¹C]FR194921 can be used as an agent for imaging adenosine A₁ receptors in vivo by positron emission tomography (PET).     

Tumor uptake of radioiodinated anti-human pulmonary surfactant-associated protein monoclonal antibody PE10 in nude mice bearing human pulmonary adenocarcinoma in combination with an unlabeled preload

This study assessed the potential use of radioimmunoscintigraphy of pulmonary alveolar Type II cells tumor with the radiolabeled anti-human surfactant-associated protein (SP) monoclonal antibody (MAb) PE 10 in combination with preloads of unlabeled MAb. The in vitro binding of iodine-125 (¹²⁵I)-labeled MAb PE 10 (1 μg), which had a specific radioactivity of 400 MBq/mg, on human pulmonary papillary adenocarcinoma NCI-H441 cells that produced SP was investigated. In NCI-H441 tumor-bearing nude mice, the tumor uptake of ¹²⁵I-MAb PE 10 (5 μg) was examined in combination with preloads of unlabeled MAb PE 10 (0, 5, 10, and 50 μg). An isotype-matched unassociated murine MAb was used as a control both in vitro and in vivo. ¹²⁵I-MAb PE 10 showed specific cell binding compared with ¹²⁵I-control MAb. Tumor uptake of ¹²⁵I-MAb PE 10 in vivo reached a peak of 4.97±0.33% injected dose per gram (%ID/g) at 48 h postinjection. Preloads of 5 and 10 μg unlabeled MAb PE 10 significantly enhanced tumor uptake at 48 h postinjection ( 5.94±0.29% ID/g and 5.72±0.29% ID/g, respectively), whereas preload of 50 μg unlabeled MAb PE 10 significantly decreased tumor uptake ( 2.75±0.32% ID/g) at 48 h. Preload of 5 μg unlabeled MAb PE 10 significantly increased the tumor-to-blood radioactivity ratio at 48 h ( 2.39±0.16). Preloads of unlabeled control MAb did not cause any significant change in tumor uptake. Immunohistochemistry showed the intracellular and pericellular patterns of SP expression in tumor cells. In conclusion, radioimmunoscintigraphy with MAb PE 10 labeled with a γ-emitting radioiodine such as ¹²³I might be a useful means of targeting pulmonary alveolar Type II tumor cells in combination with preloading with an optimal dose of the unlabeled MAb.     

[Dy]Dy/Ho hydroxide macroaggregates: an in vivo generator system for radiation synovectomy

Radiation synovectomy is an effective treatment in patients suffering from inflammatory-rheumatoid and degenerative joint diseases. The aim of this work was to examine the feasibility of preparing dysprosium-166 (¹⁶⁶Dy)/holmium-166(¹⁶⁶Ho) hydroxide macroaggregates ([¹⁶⁶Dy]Dy/¹⁶⁶Ho-HM) as an in vivo generator for radiation synovectomy evaluating whether the stability of ¹⁶⁶Dy-HM and ¹⁶⁶Ho-HM complexes is maintained when the daughter ¹⁶⁶Ho is formed. The Monte Carlo (MCNP4B) theoretical depth dose profile for the in vivo [¹⁶⁶Dy]Dy/¹⁶⁶Ho generator system in a joint model was calculated and compared with that produced by ⁹⁰Y, ¹⁵³Sm and ¹⁶⁶Ho. ¹⁶⁶Dy was obtained by neutron irradiation of enriched ¹⁶⁴Dy₂O₃ in a Triga Mark III reactor. Macroaggregates were prepared by reaction of [¹⁶⁶Dy]DyCl₃ with 0.5 M NaOH in an ultrasonic bath. [¹⁶⁶Dy]Dy/¹⁶⁶Ho-HM was obtained with radiochemical purity >99.5% and with the majority of particles in the 2–5 μm range. In vitro studies demonstrated that the radio-macroaggregates are stable in saline solution and human serum without a significant change in the particle size over 14 d, suggesting that no translocation of the daughter nucleus occurs subsequent to β⁻ decay of ¹⁶⁶Dy. Biological studies in normal rats demonstrated high retention in the knee joint even 7 d after [¹⁶⁶Dy]Dy/¹⁶⁶Ho-HM administration. The Monte Carlo (MCNP4B) theoretical depth dose profiles in a joint model, showed that the in vivo [¹⁶⁶Dy]Dy/¹⁶⁶Ho generator system would produce 25% and 50% less radiation dose to the articular cartilage and bone surface, respectively, than that produced by ⁹⁰Y or pure ¹⁶⁶Ho in a treatment with the same therapeutic dose to the synovium surface. Despite that ¹⁵³Sm showed the best depth dose profile sparing doses to healthy tissues, the use of ¹⁶⁶Dy could provide the advantage of being applied in patients that cannot be reached within a few hours from a nuclear reactor and to produce less radiation exposure to the medical personnel during the radiopharmaceutical administration.     

Processing of reactor-produced W for fabrication of clinical scale alumina-based W/Re generators

The traditional technique for processing of reactor-irradiated ¹⁸⁶W-enriched tungsten oxide (WO₃) targets involves formation of ¹⁸⁸W-sodium tungstate solutions by target dissolution in 0.1 M NaOH. Following long irradiations (> 21 days) in the ORNL High Flux Isotope Reactor (HFIR) the ¹⁸⁶WO₃ targets contain a NaOH-insoluble ¹⁸⁸W-labeled black solid (approx. 30–50% of total activity) which decreases the yield and specific activity of the processed ¹⁸⁸W (e.g. 5–6 mCi/mg ¹⁸⁶W for a 79-day irradiation). The black material is postulated to represent a “tungsten blue” insoluble polymeric form of tungsten oxide, which we have now found to dissolve in 0.1 M NaOH containing 5% sodium hypochlorite solution. Complete dissolution results in a significant increase in the yield and specific activity of sodium ¹⁸⁸W-tungstate. As an alternative approach, irradiated ¹⁸⁶W-enriched metal targets dissolve in sodium hydroxide solution by cautious addition of < 30% hydrogen peroxide. Sodium ¹⁸⁸W-tungstate solutions prepared from processing of such metal targets show no evidence of residual black insoluble material. Specific activity values for completely dissolved HFIR-irradiated ¹⁸⁶W targets have increased to 10 mCi/mg (43.5 days) and 12.9 mCi/mg (49.2 days). Large clinical scale (> 1 Ci) generators prepared from hypochlorite-processed ¹⁸⁶W oxide or peroxide-processed ¹⁸⁶W metal targets exhibit the expected ¹⁸⁸Re high yield and low ¹⁸⁸W breakthrough.     

Experimental studies on the proton-induced activation reactions of molybdenum in the energy range 22–67 MeV

The production cross-sections of ^99,93mMo, ^96,95,95m,94Tc, ^96,95,92m,90Nb, ^89,88,86Zr and ^88,87,86Y radionuclides for proton-induced reactions on molybdenum were measured with molybdenum targets of natural isotopic composition using a stacked-foil activation technique in the energy range 22–67 MeV. The thick target integral yields were also deduced for each reaction using the measured cross-sections from the respective threshold up to 67 MeV. The results have given new data for all of the investigated radionuclides. The results of the present experiment showed excellent agreement with the earlier reported data in the lower energy region.     

Remote processing, delivery and injection of H2[O] produced from a N2/H2 gas target using a simple and compact apparatus

We report here a simple apparatus for remote trapping and processing of H₂[¹⁵O] produced from the N₂/H₂ target. The system performs a three step operation for H₂[¹⁵O] delivery at the PET imaging facility which includes the following: (i) collecting the radiotracer in sterile water; (ii) adjusting preparation pH through removal of radiolytically produced ammonia, while at the same time adjusting solution isotonicity; and (iii) delivery of the radiotracer preparation to the injection syringe in a sterile and pyrogen-free form suitable for human studies. The processing apparatus is simple, can be remotely operated and fits inside a Capintec Dose Monitoring Chamber for direct measurement of accumulated radioactivity. Using this system, 300 mCi of H₂[¹⁵O] (15 μA of 8 MeV D⁺ on target) is transferred from target through 120 m × 3.18 mm o.d. Impolene tubing to yield 100 mCi of H₂[¹⁵O] which is isotonic, neutral and suitable for human studies.

A remote hydraulically driven system for i.v. injection of the H₂[¹⁵O] is also described. The device allows for direct measurement of syringe dose while filling, and for easy, as well as safe transport of the injection syringe assembly to the patient's bedside via a shielded delivery cart. This cart houses a hydraulic piston that allows the physician to “manually” inject the radiotracer without directly handling the syringe.     

Alternative quality control for technetium-99m IDA complexes

A quality control procedure for ^99mTc-IDA complexes based on the use of C₁₈ Sep-pak^TM cartridges is developed and the validation of the procedure presented. C₁₈ Sep-pak^TM cartridges are pretreated by washing with 95% ethanol followed by 10⁻³ N hydrochloric acid. A small amount of the ^99mTc-IDA complex is applied, washed with 10⁻³ N hydrochloric acid and eluted with 95% ethanol. The radiochemical purity values obtained for ^99mTc-mebrofenin and ^99mTc-disofenin using this Sep-pak^TM procedure are comparable to those obtained using the standard two strip (ITLC-SG/100% methanol, ITLC-SA/20% saline) procedure.