Production Of 123I Research Articles

Evaluation of excitation functions of 127I(p,xn) 121,122, 123, 125,127Xe reactions, with particular reference to the production of 127Xe and 123I for medical use

Cross section data for the formation of 121,122,123,125,127Xe via proton induced reactions on 127I were critically analyzed. Three nuclear model codes (TALYS 1.9, ALICE-IPPE, and EMPIRE 3.2) were used to ensure the consistency and reliability of the experimental data. Utilizing a well-developed evaluation methodology, a recommended fit for each excitation function was obtained, based on theoretical predictions of nuclear models and experimental cross sections. By using the recommended/reference results, thick target yields were calculated for each production route and its associated impurity reactions. The indirect production of the radionuclides 121,122,123,125I was explored. Special attention was paid to standardization of cross section data for the production of the medically important radionuclides 127Xe and 123I via the routes 127I(p,n)127Xe and 127I(p,5n)123Xe(EC, β+)123I, respectively.

A new 124Xe irradiation system for 123I production

Since 2001, Nuclear and Energy Research Institute IPEN-CNEN has produced weekly ultrapure iodine-123, using a manual irradiation system, fully developed in IPEN. Iodine-123 radiopharmaceuticals have been produced and distributed to hospitals and clinics of nuclear medicine, where several diagnostic imaging procedures for thyroid, brain and cardiovascular functions are performed. Due to the short half-life and emission of low-energy photons, this radioisotope becomes suitable for diagnosis in children. In the present work, the technical and constructive aspects of a new fully automated irradiation system, dedicated to 123I routine production, employing enriched xenon-124 gas as the target material is presented. This new system consists of a target, a water and helium cooling system, a cryogenic system, an electric power system, and a control and process monitoring unit, composed of supervisory software, connected to a programmable logic controller via personal computer. In this new concept, there is no need for human intervention during radioisotope production, reducing the possibility of eventual failures or incidents involving radioactive material. By using this new system, a specific yield of 2.70 mCi/μAh per irradiation was achieved in validation runs, and after three years of routine production of iodine-123, the system showed reliability and resilience.

Cross-Section Calculations for the Production of 123I and 124I Radioisotopes via (p,n) and (p,2n) Reactions Using Collective Nuclear Level Density Model

Some isotopes such as 123I and 124I are useful in medical science, and thus, the production of these isotopes has great importance. Iodine-123 is the gamma-emitting radioisotope of radioiodine, and 124I is the long-lived positron-emitting radioisotope of radioiodine, and they have applications in diagnosis via both Single Photon Emission Computed Tomography (SPECT)/Positron Emission Tomography (PET) and radiotherapy. Therefore, many theoretical and experimental studies are performed for these isotopes. In this study, the cross sections of the 123Te(p,n), 124Te(p,n), and 124Te(p,2n) reactions up to 31 MeV, where 123I and 124I can be produced, are calculated by importing the Collective Semi-Classical Fermi Gas Model (CSCFGM) to the Talys 1.96 computer code. The predictions are compared with the default theoretical calculations of Talys 1.96 and existing experimental data taken from the EXFOR library. The results are in good agreement with the experimental data, and therefore, CSCFGM looks to be a useful tool for predicting the production reactions of some therapeutic isotopes.

Efficiency of 124I radioisotope production from natural and enriched tellurium dioxide using 124Te(p,xn)124I reaction

Background124I Iodine (T_{1/2} = 4.18 d) is the only long-life positron emitter radioisotope of iodine that may be used for both imaging and therapy as well as for 131I dosimetry. Its physical characteristics permits taking advantages of the higher Positron Emission Tomography (PET) image quality, whereas the availability of new molecules to be targeted with 124I makes it a novel innovative radiotracer probe for a specific molecular targeting.ResultsIn this study Monte Carlo and SRIM/TRIM modelling was applied to predict the nuclear parameters of the 124I production process in a small medical cyclotron IBA 18/9 Cyclone. The simulation production yields for 124I and the polluting radioisotopes were calculated for the natural and enriched 124TeO2 + Al2O3 solid targets irradiated with 14.8 MeV protons. The proton beam was degraded energetically from 18 MeV with 0.2 mm Havar foil. The 124Te(p,xn)124I reactions were taken into account in the simulations. The optimal thickness of the target material was calculated using the SRIM/TRIM and Geant4 codes. The results of the simulations were compared with the experimental data obtained for the natural TeO2 +Al2O3 target. The dry distillation technique of the 124-iodine was applied.ConclusionsThe experimental efficiency for the natural Te target was better than 41% with an average thick target (>0.8 mm) yield of 1.32 MBq/μAh. Joining the Monte Carlo and experimental approaches makes it possible to optimize the methodology for the 124I production from the expensive Te enriched targets.

Possibility of Increasing Cyclotron Production of 123I at the NRC Kurchatov Institute

Possibility of Increasing Cyclotron Production of 123I at the NRC Kurchatov Institute

Synthesis, Radiolabeling, and Preliminary in vivo Evaluation of [68Ga] IPCAT-NOTA as an Imaging Agent for Dopamine Transporter.

IntroductionNovel radiotracer development for imaging dopamine transporters is a subject of interest because although [99mTc]TRODAT-1, [123I]β-CIT, and [123I]FP-CIT are commercially available; 99Mo/99mTc generator is in short supply and 123I production is highly dependent on compact cyclotron. Therefore, we designed a novel positron emission tomography (PET) tracer based on a tropane derivative through C-2 modification to conjugate NOTA for chelating 68Ga, a radioisotope derived from a 68Ge/68Ga generator.MethodsIPCAT-NOTA 22 was synthesized and labeled with [68Ga]GaCl4− at room temperature. Biological studies on serum stability, LogP, and in vitro autoradiography (binding assay and competitive assay) were performed. Furthermore, ex vivo autoradiography, biodistribution, and dynamic PET imaging studies were performed in Sprague Dawley rats.Results[68Ga]IPCAT-NOTA 24 obtained had a radiochemical yield of ≥90% and a specific activity of 4.25 MBq/nmol. [68Ga]IPCAT-NOTA 24 of 85% radiochemical purity (RCP%) was stable at 37°C for up to 60 minutes in serum with a lipophilicity of 0.88. The specific binding ratio (SBR%) reached 15.8 ± 6.7 at 60 minutes, and the 85% specific uptake could be blocked through co-injection at 100- and 1000-fold of the cold precursor in in vitro binding studies. Tissue regional distribution studies in rats with [68Ga]IPCAT-NOTA 24 showed striatal uptake (0.02% at 5 minutes and 0.007% at 60 minutes) with SBR% of 6%, 25%, and 62% at 5–15, 30–40, and 60–70 minutes, respectively, in NanoPET studies. The RCP% of [68Ga]IPCAT-NOTA 24 at 30 minutes in vivo remained 67.65%.ConclusionData described here provide new information on the design of PET probe of conjugate/pendent approach for DAT imaging. Another chelator or another direct method of intracranial injection must be used to prove the relation between [68Ga]IPCAT-NOTA 24 uptake and transporter localization.

124,125Te(p,xn)123,124I ve 123,124Te(d,xn)123,124I İçin Reaksiyon Tesir Kesitleri

The iodine isotopes of 123I and 124I with half lives of 13.2 hours and of 4.2 days respectively are commonly used in nuclear medicine and are becoming more widespread recently. The isotope of 123I is ideal for a gamma camera with the energy of 159 keV to the patient with a much less radiation dose whereas the radionuclide 124I is a positron emitter and is useful in some positron emission tomography (PET) for radiopharmaceuticals. The gamma ray will penetrate tissue very effectively without an excessive radiation dose. Iodine-123 decays by electron capture emitting gamma rays at 0.028 and 0.160 MeV that has high penetration power to tissue but no excessive radiation dose. The half-life of 4.2 d and the 23% positron decay allow localization with monoclonal antibodies, and the PET imaging which makes Iodine-124 radionuclide a good candidate for being a diagnostic and a therapeutic.This study aims on the calculation of the excitation functions for 123I and 124I various production mechanisms. TALYS 1.6 is used to calculate the reaction cross sections for 123,124,125Te bombarded with protons and deuteriums to produce 123,124I radioisotopes commonly used in medical applications. The calculated results were compared with available experimental results from EXFOR. The results are interpreted in terms of deciding which radoisotope is more appropriate to produce with which reaction and evaluating the effects in the reaction mechanisms. In addition, the relative reaction cross-sections of 123,124I radioisotopes obtained by bombarding 124Te target with protons were discussed, and the common reaction for the production of 123I was evaluated to be the 124Te(p, 2n)123I reaction on the highly enriched 124Te. Thus, it is considered that a very high level of enrichment on the target must be achieved in order to prevent contamination caused by competing reactions of (p, n) and (p,2n). It is concluded that 123I production is more suitable for small and mediumi-sized cyclotrons.

Cyclotron Production of Iodine-124

The current state of methods of production of radionuclide 124I for nuclear medicine is analyzed. The review is focused on finding methods for enhancement of cyclotron production of the 124I radionuclide. The influence of the chosen nuclear reactions, the irradiation conditions, the target material, and the methods of manufacturing and cooling of the irradiated targets on the radionuclide yield is considered.

Deuteron induced reactions on tellurium: An alternative for production of 123I?

New experimental cross sections in the 13–21.5 MeV domain of deuteron induced reactions on Te complementing the 35-year-old publication by Zaidi et al. [1] were determined. Excitation functions for the 121,123,124,125,126,128,130,131I-radioisotopes and 131gTe were obtained through stacked foil activation method. Values for 128,121I and 131Te are the first ever presented for natTe.A comparison of our new cross-section values is made to the values reported in the earlier study where relevant and with the theoretical excitation functions reconstructed from the reaction cross sections available in the TENDL-2017 (TALYS 1.6 calculations) on-line library.For discussion of the possibility as a production route the yields of 123,124,125,126,131I are calculated from fits to our measurements, complemented by theoretical values. Contributing reactions and contaminations in selected energy windows are discussed and compared to earlier conclusions.

Investigation of the thermal performance of natTe target for 124I production in the RARS cyclotron

Abstract Regarding the low thermal conductivity of natTe element, the provision of an effective cooling system is one of the critical issues in cyclotron targetry to prevent melting of target matter during the irradiation to 124I production via natTe(p,xn)124I reaction. Heat transfer on Te target and efficiency of cooling fluid in the solid target system have been simulated based on a Finite Element Analysis (FEA) code for the thermal behavior of the target during the irradiation and under different beam currents, coolant flow rates, substrate matters and target geometry. The results on the routinely used solid target in Radiation Application Research School (RARS) cyclotron showed that in a 3 m/s coolant flow rate, by using a fined-cooling system and a nickel substrate coated on copper backing plate, the irradiation beam current can be raised up to 180 μA without any risk of melting. The cooling flow rates greater than 3 m/s do not noticeably improve the heat dispersion of target layer. As expected, a linear increase was observed for the temperature and temperature gradient of plates in the beam currents of 100–300 μA.

Experimental and FLUKA study relevant to the production of 124I through natTe(p,xn) reaction at a medium-sized cyclotron

In this study, 124I PET positron emitter was produced by 29.5 MeV protons irradiation of natural tellurium electroplated on a nickel-coated copper substrate at a current of 150.3 μA h. The routinely separation method of ion-exchange chromatography was adopted and 93% efficiency was achieved for this process. The average yield of 124I at the End of Bombardment (EOB) was 3.9 MBq/μA h (0.105 mCi/μA h). Additionally, the production process was simulated by the FLUKA, and the yield of 4.3 MBq/μA h (0.116 mCi/μA h) was estimated at the EOB for produced 124I. A reasonable agreement was achieved between the simulation results and experimental data.

Investigation of 123I production using electron accelerator

The possibility of 123I isotope production with the help of the high-intensity bremsstrahlung photons produced by the electron beam of the LUE50 linear electron accelerator at the A.I. Alikhanyan National Science Laboratory (Yerevan Physics Institute [YerPhI]) is considered. The production method has been established and shown to be successful. The 124Xe(γ,n)123Xe→123I nuclear reaction has been investigated and the cross-section was calculated by nuclear codes TALYS 1.6 and EMPIRE 3.2. The optimum parameter of the thickness of the target was determined by GEANT4 code. For the normalized yield of 123I, the value of 143Bq/(mg·μA·h) has been achieved.

Determination of the 121Te gamma emission probabilities associated with the production process of radiopharmaceutical NaI[123I

The 123I is widely used in radiodiagnostic procedures in nuclear medicine. According to Pharmacopoeia care should be taken during its production process, since radionuclidic impurities may be generated. The 121Te is an impurity that arises during the 123I production and determining their gamma emission probabilities (Pγ) is important in order to obtain more information about its decay. Activities were also obtained by absolute standardization using the sum-peak method and these values were compared to the efficiency curve method.

An overview of 124I production at a medical cyclotron by ALICE/ASH, EMPIRE-3.2.2 and TALYS-1.6 codes

Excitation functions of proton, deuteron and alpha induced nuclear reactions on enriched tellurium and antimony isotopes and also natural antimony were calculated by ALICE/ASH, EMPIRE-3.2.2 and TALYS-1.6 nuclear codes. Therefrom, the production yield of 124I nuclide and its formed impurities were calculated by using the evaluation results. The calculated cross sections were compared with available experimental values in literatures. According to results, 124Te(p,n)124I reaction is the method of choice due to formation of higher amount of 124I nuclide and low levels of 125I as an major concern in 124I production.

Determination of impurities in 124I samples by high resolution gamma spectrometry

124I is a radionuclide used in the diagnosis of tumors. The National Health Agency requires identification and activity measurement of impurities. Using gamma spectrometry with an efficiency calibrated high-purity germanium detector, impurities 125I and 126I in an 124I production sample were identified. Activity ratios of 125I and 126I to 124I were approximately 0.5% and 98%, respectively.

Ion-exchange separation of radioiodine and its application to production of 124I by alpha particle induced reactions on antimony

Abstract The basic parameters related to radiochemical separation of iodine from tellurium and antimony by anion-exchange chromatography using the resin Amberlyst A26 were studied. The separation yield of 124I amounted to 96% and the decontamination factor from 121Te and 122Sb was > 104. The method was applied to the production of 124I via the 123Sb(α, 3n) reaction. In an irradiation of 110 mg of natSb2O3 (thickness ∼ 0.08 g/cm2) with 38 MeV α-particles at 1.2 μA beam current for 4 h, corresponding to the beam energy range of E α = 37 → 27 MeV, the batch yield of 124I obtained was 12.42 MBq and the 125I and 126I impurities amounted to 3.8% and 0.7%, respectively. The experimental batch yield of 124I amounted to 80% of the theoretically calculated value but the level of the radionuclidic impurities were in agreement with the theoretical values. About 96% of the radioiodine was in the form of iodide and the inactive impurities (Te, Sb, Sn) were below the permissible level. Due to the relatively high level of radionuclidic impurity the 124I produced would possibly be useful only for restricted local consumption or for animal experiments.

Development of an ion-exchange method for separation of radioiodine from tellurium and antimony and its application to the production of 124I via the 121Sb(α,n)-process

A novel anion-exchange chromatographic method for separation of radioiodine from an antimony target irradiated with 3He- or α-particles was developed, with separation yield of radioiodine amounting to 90 ± 5 % and its decontamination factor from the Te and Sb radionuclides to ~104. The optimized separation method developed was then applied to the production of 124I via the 121Sb(α,n)124I process using a highly enriched 121Sb target. Quality control tests showed that the separated 124I occurred >99 % as iodide and the longer lived impurities 126I and 125I amounted to 0.16 % and <0.05 %, respectively. The trace level of inactive Sb impurity was determined by ICP–OES.

Radiopharmaceutical Chemistry with Iodine-124: A Non-Standard Radiohalogen for Positron Emission Tomography

Positron emission tomography (PET) is a powerful molecular imaging technology with the ability to image and monitor molecular events in vivo and in real time. With the increased application of PET radiopharmaceuticals for imaging physiological and pathological processes in vivo, there is a demand for versatile positron emitters with longer physical and biological half-lives. Traditional PET radionuclides, such as carbon-11 ((11)C) and fluorine-18 ((18)F), have relatively short half-lives (20 min and 110 min, respectively). Among the currently available positron emitters, the non-standard radiohalogen iodine-124 ((124)I) has the longest physical half-life at 4.2 d. This, combined with the well characterized radiochemistry of radioiodine, is contributing to the increasing utility of (124)I in investigating slow and complex pharmacokinetic processes in clinical nuclear medicine and small animal PET imaging studies. This review will summarize the progress to date on the potential of (124)I as a positron emitting nuclide for molecular imaging purposes, beginning with the production of (124)I. Particular emphasis will be placed on the basic radiochemistry as it applies to the production of various (124)I-labeled compounds, from small molecules, to biomolecules such as peptides and proteins, and finally to macromolecules like nanoparticles. The review will conclude by highlighting promising future directions in using (124)I as a positron emitter in PET radiochemistry and molecular imaging.

Excitation functions of α-particle induced reactions on enriched 123Sb and natSb for production of 124I

Excitation functions of (α,xn) reactions on 98.28% enriched (123)Sb and on (nat)Sb were measured from 9 to 40 MeV. The data could be described well in terms of statistical and precompound models using the code TALYS. The discrepancies in the literature data for the formation of (125)I and (126)I were solved. The nuclear reaction (123)Sb(α,3n)(124)I on an enriched target appears to be interesting for the production of (124)I (T(1/2)=4.18 d) over the energy range E(α)=42→32 MeV, its yield being 11.7 MBq/μAh. The levels of the radionuclidic impurities (125)I and (126)I amount to 1.8% and 0.6%, respectively. The use of (nat)Sb as target material for (124)I production is unsuitable due to the high level of (123)I impurity.

Limitation of the long-lived 121Te contaminant in production of 123I through the 124Xe(p,x) route

The 13.2 h half-life radioisotope (123)I is widely used in clinical nuclear medicine diagnosis. At present it is mostly produced in nca form by proton irradiation of highly enriched (124)Xe in dedicated gas target set-ups and relying on the decay chain (123)Cs-(123)Xe-(123)I. Depending on the irradiation conditions contamination with long-lived (121)Te, a daughter product of the co-produced rather short lived (121)I, occurs and can limit the useful shelf life of the (123)I solution. Excitation function of the (124)Xe(p,α)(121)I, (124)Xe(p,2n)(123)Cs and (124)Xe(p,2p)(123)Xe reactions are measured up to 35 MeV using the stacked gas cell technique and high-resolution γ-ray spectrometry. The experimental data were compared with the earlier literature values, with new results of the ALICE-IPPE and EMPIRE-II codes and with the data taken from the TENDL-2009 database. Existing discrepancies in cross-section data are largely solved and new recommended values are proposed. From fits to the new excitation curves integral (123)I batch yields and (121)Te contaminations for realistic production conditions are derived. Optimization of irradiation and cooling times and energy degradation in the target can strongly influence the contamination level.