Enriched 100Mo Research Articles

Determination of the experimental yield of 99mTc in (p,2n) nuclear reaction on enriched 100Mo sample with application of 11-MeV medical cyclotron

This paper presents the measured thick target yield of 99mTc from molybdenum sample with 92.2% enrichment in 100Mo isotope via the (p,2n) nuclear reaction channel. The yield was determined experimentally with application of the 11-MeV medical cyclotron Eclipse RD, equipped with a new target assembly developed for solid sample irradiations. The experimental physical yield was measured to be 30.9 ± 1.3 MBq/μAh. This result was compared with theoretical calculations and results of other authors. The features of irradiation conditions that may have an influence on produced activity were studied and analyzed.

GEANT4 based simulation study of converter and direct target design and optimization of target for 99Mo production using 30 MeV electron linear accelerator

A 30 MeV, 5–10 kW beam power electron linac is under development at SAMEER for radio-isotope production. An enriched 100Mo target will be irradiated to produce 99Mo which will be eluted to give 99mTc. Two approaches of 100Mo target irradiation -converter and direct are studied using GEANT4 simulations. The main aim of this study is to optimize the 100Mo target geometry for maximum yield. It is observed that direct target irradiation gives better activity as compared to converter target approach.

Status of AMoRE

AMoRE is to search for neutrinoless double beta decay using Mo-100 enriched crystal scintillators at an ultra-low temperature. We have understood the major background sources and how they can be reduced from a pilot stage run in the Yangyang underground laboratory. AMoRE-I is currently running with twelve 48deplCa100MoO4 and five Li2 100MoO4 crystals with a total mass of enriched 100Mo 2.8 kg. The detector design for the main stage of the experiment, AMoRE-II, has been finalized and the detector is under construction in YemiLab, a new underground laboratory located in an iron mine with an average depth 2500 meter of water equivalent.

Side-reaction products identified for photo-nuclear production of99Mo

Production of 99Mo by the 100Mo (γ, n)99Mo reaction through the bremsstrahlung process using an electron accelerator is one of the feasible options currently pursued by several countries. Here we report experimental results on identification of side-reaction products after the irradiation of natural and enriched 100Mo targets. Side-reaction products identified include various Mo, Nb and Zr isotopes. Comparison of experimentally determined reaction production rates with those determined based on theoretical cross-sections will be presented. Moreover, activation products formed due to presence of impurities introduced during the manufacturing of the Mo targets will also be discussed.

Demonstration of the MOEX Process Using Additive-Manufacturing-Fabricated Annular Centrifugal Contactors

ABSTRACTAdditive manufacturing/3D printing is a rapidly maturing field with potential advantages for the fabrication of chemical processing equipment. A demonstration of the molybdenum solvent-extraction process, developed to recover Mo for the production of 99Mo/99mTc from enriched 98Mo or 100Mo, was accomplished using a nine-stage bank of additive-manufacturing-fabricated 2-cm annular centrifugal contactor-separator devices. The results from the demonstration are presented along with the benefits and shortcomings of the 3D printed contactors. This paper also discusses recent developments in the design of 3D printed contactors in order to improve reliability and mitigate the effects of chemical degradation of additive-manufacturing media.

Influence of enriched 100Mo on Mo reaction yields

In accelerator-driven 99Mo/99mTc production, the 100Mo enrichment level should be chosen carefully as it greatly affects the yields of the involved Mo reactions. To facilitate selecting the 100Mo enrichment level, we defined a figure of merit called density change coefficient and developed its calculation program. Density change coefficients calculated for nine commercial enriched 100Mo products are presented and their use in selecting the 100Mo enrichment level is discussed.

Measurement of 99Mo production cross-section from the 100Mo(n,2n) reaction with quasi monoenergetic neutron based on the 9Be(p,n) reaction

The production cross-section of the medical isotope, 99Mo from the enriched 100Mo(n,2n) reaction with the average neutron energies of 21.9 and 26.5 MeV has been determined for the first time by using an off-line γ-ray spectrometric technique. The average neutron energies were generated by using the 9Be(p,n) reaction with the proton energies of 35 and 45 MeV from the MC50 cyclotron of the Korea Institute of Radiological and Medical Sciences (KIRAMS) at Seoul, South Korea. The 100Mo(n,2n) reaction cross-section as a function of neutron energy was also calculated theoretically by using the computer code TALYS-1.8 and EMPIRE-3.2 Malta. The experimental results are in close agreement with the theoretical values from TALYS-1.8. However, the present data at the neutron energy of 21.9 MeV is slightly lower and at 26.5 MeV is higher than the values from EMPIRE-3.2 Malta.

Impurities in Tc-99m radiopharmaceutical solution obtained from Mo-100 in cyclotron

The gamma emitting impurities in 99mTc solution obtained from enriched molybdenum 100Mo metallic target after its irradiation in a cyclotron were measured using a high-purity germanium (HPGe) detector. The radioactivity range of tested samples of 99mTc was rather low, in the range from 0.34 to 2.39 MBq, thus creating a challenge to investigate the standard measurement HPGe system for impurity detection and quantification. In the process of 99mTc separation from irradiated target the AnaLig® Tc-02 resin, Dionex H+ and Alumina A columns were used. Fractions of eluates from various steps of separation process were taken and measured for radionuclidic purity. The overall measurement sensitivity of gamma emitters in terms of minimum detectable activity (MDA) was found at the level of 14–70Bq with emission lines in range of 36 – 1836keV resulting in impurity content range of 6.7 × 10−4 to 3.4 × 10−3 % for 93Tc, 93mTc, 94Tc, 94mTc, 95Tc, 95mTc, 96Tc 96Nb, 97Nb, 99Mo contaminants and 9.4 × 10−3 % for 97mTc. The usefulness of the chosen measurement conditions and the method applied to testing the potential contaminators was proved by reaching satisfactory results of MDAs less than the criteria of impurity concentration of all nuclides specified in the European Pharmacopoeia.

Production of 99Mo/99mTc via photoneutron reaction using natural molybdenum and enriched 100Mo: part 1, theoretical analysis

A theoretical analysis was performed for the production of 99Mo via the 100Mo(γ,n)99Mo reaction using natural (natMo) and enriched (100Mo) molybdenum targets in a modified NIRTA® Targetry system. High energy electrons from a linear accelerator were simulated on a tungsten converter to produce bremsstrahlung incident on molybdenum targets using the TALYS computer code. All open channels and decay schemes were used to assess the production rates and final amounts of radioactive and stable components at end-of-bombardment (3-day irradiation), and after 2 h of cooling. Computations were performed at an accelerator energy of 40 MeV, correlating to a maximized photon fluence at 14 MeV. Impurities of Zr and Nb were found when utilizing enriched 100Mo (excluding Mo isotopes). Targets utilizing natMo added substantial stable and radioactive impurities of Mo, Nb, Zr, Y, and Sr; however, all but the Mo impurities can be readily separated. This study confirms the potential of producing 99Mo via 100Mo(γ,n)99Mo using natMo with manageable impurities.

Production efficiency and radioisotopic purity of 99mTc formed using the (p,2n) reaction on a highly enriched 100Mo target

The [Formula: see text]Tc isomer was produced using the [Formula: see text] reaction on highly enriched [Formula: see text]Mo samples. The Thick Target Yields were determined in the energy range from 16 MeV to 26 MeV and compared with the values calculated using the most recent cross-section recommendations from the literature. The generated impurities were also determined. It was shown that for 99.815 ± 0.010% enriched samples, only reactions induced on [Formula: see text]Mo are of importance. The ratio of the number of atoms of [Formula: see text]Tc to all produced Tc nuclei was studied as a function of irradiation time and bombarding energy.

MOEX: Solvent extraction approach for recycling enriched 98Mo/100Mo material

ABSTRACTSeveral promising pathways exist for the production of 99Mo/99mTc using enriched 98Mo or 100Mo. Use of Mo targets requires a major change in current generator technology, and the necessity for an efficient recycle pathway to recover valuable enriched Mo material. High recovery yields, purity, suitable chemical form and particle size are required. Results on the development of the MOEX – molybdenum solvent extraction – approach to recycle enriched Mo material are presented. The advantages of the MOEX process are very high decontamination factors from potassium and other elements, high throughput, easy scalability, automation and minimal waste generation.

Imaging study of using radiopharmaceuticals labeled with cyclotron-produced 99mTc

Cyclotron-produced 99mTc (CPTc) has been recognized as an attractive and practical substitution of reactor/generator based 99mTc. However, the small amount of 92-98Mo in the irradiation of enriched 100Mo could lead to the production of other radioactive technetium isotopes (Tc-impurities) which cannot be chemically separated. Thus, these impurities could contribute to patient dose and affect image quality. The potential radiation dose caused by these Tc-impurities produced using different targets, irradiation conditions, and corresponding to different injection times have been investigated, leading us to create dose-based limits of these parameters for producing clinically acceptable CPTc. However, image quality has been not considered.The aim of the present work is to provide a comprehensive and quantitative analysis of image quality for CPTc. The impact of Tc-impurities in CPTc on image resolution, background noise, and contrast is investigated by performing both Monte-Carlo simulations and phantom experiments. Various targets, irradiation, and acquisition conditions are employed for investigating the image-based limits of CPTc production parameters. Additionally, the relationship between patient dose and image quality of CPTc samples is studied. Only those samples which meet both dose- and image-based limits should be accepted in future clinical studies.

Separation of Mo from Nb, Zr and Y: applicability in the purification of the recovered enriched 100Mo used in the direct production of 99mTc in cyclotrons

The direct production of 99mTc in cyclotrons by the proton irradiation of highly enriched 100Mo requires recovery of the costly enriched 100Mo from the irradiated target to keep the cost of 99mTc within the affordable limit. Various isotopes (both radioactive and stable) of Mo, Nb, Zr, and Y may be concomitantly produced directly or indirectly by several nuclear reactions. As a result of this, the recovered 100Mo may be contaminated with those impurities. This paper describes a simple chemical separation method to near complete removal of Nb, Zr, and Y impurities in Mo. Even the chance of contamination of recovered 100Mo due to 97Mo, arising from 100Mo(p, α)97Nb → 97Mo, may be reduced by 56 % if the purification is completed in 1 h after the end of irradiation.

Scintillating bolometers based on ZnMoO4 and Zn100MoO4 crystals to search for 0ν2β decay of 100Mo (LUMINEU project): first tests at the Modane Underground Laboratory

The technology of scintillating bolometers based on zinc molybdate (ZnMoO4) crystals is under development within the LUMINEU project to search for 0ν2β decay of 100Mo with the goal to set the basis for large scale experiments capable to explore the inverted hierarchy region of the neutrino mass pattern. Advanced ZnMoO4 crystal scintillators with mass of ∼0.3 kg were developed and Zn100MoO4 crystal from enriched 100Mo was produced for the first time by using the low-thermal-gradient Czochralski technique. One ZnMoO4 scintillator and two samples (59 g and 63 g) cut from the enriched boule were tested aboveground at milli-Kelvin temperature as scintillating bolometers showing a high detection performance. The first results of the low background measurements with three ZnMoO4 and two enriched detectors installed in the EDELWEISS set-up at the Modane Underground Laboratory (France) are presented.

Production and separation of 99mTc from cyclotron irradiated 100/naturalMo targets: a new automated module for separation of 99mTc from molybdenum targets

The direct production of 99mTc through (p, 2n) reaction on natural molybdenum target and enriched 100Mo target was investigated. Separation of technetium radionuclide from the irradiated 100Mo target by a new method using Dowex-1 ion exchange resin as well as by the standard solvent extraction (methyl ethyl ketone) method was studied. An automated computer controlled module was developed based on the Dowex-1 separation methodology. The new chemical separation method recovered more than 80 % of 99mTc from the irradiated target. The recovered pertechnetate had requisite radionuclidic, radiochemical and chemical purity for the preparation of 99mTc-radiopharmaceuticals.

Assessment of the direct cyclotron production of 99mTc: An approach to crisis management of 99mTc shortage

Nowadays, the cyclotron production of technetium-99m (99mTc) has been increased, due to the worldwide 99mTc generator shortage. In the present work, an improved strategy for the production of 99mTc, using the proton irradiation of the enriched 100Mo was developed. The performance of this method in terms of the production yield, chemical purity, radiochemical purity, as well as radionuclide purity was evaluated. The average production yield was measured to be 356MBqμA−1h−1. A good agreement was found between the calculated production yield and the experimental one. The radiochemical separation and total recovery yields of 99mTc were 92% and 69%, respectively. The radiochemical and the radionuclide purities of the 99mTc were 99% and >99.99% at the end of purification, respectively. The results of quality control tests (QC) support the concept that cyclotron-produced 99mTc is suitable for preparation of USP-compliant.

Recycle of enriched Mo targets for economic production of 99Mo/99mTc medical isotope without use of enriched uranium

A new recycle process for recovery of enriched 98Mo or 100Mo used for production of 99Mo/99mTc medical isotope was developed. In this process, Mo is precipitated from spent NorthStar Mo/Tc generator solution containing ~200 g/L Mo as K2MoO4 in 5 M KOH using acetic acid and then washed with nitric acid. High purification factors from potassium were achieved, and typical Mo recovery yields were ~95 %. The recycle process was performed with up to 260 g of Mo per batch and can be easily implemented for processing of up to 400 g of Mo.

Radioisotopic Purity of Sodium Pertechnetate 99mTc Produced with a Medium-Energy Cyclotron: Implications for Internal Radiation Dose, Image Quality, and Release Specifications.

Cyclotron production of 99mTc is a promising route to supply 99mTc radiopharmaceuticals. Higher 99mTc yields can be obtained with medium-energy cyclotrons in comparison to those dedicated to PET isotope production. To take advantage of this capability, evaluation of the radioisotopic purity of 99mTc produced at medium energy (20-24 MeV) and its impact on image quality and dosimetry was required. Thick 100Mo (99.03% and 99.815%) targets were irradiated with incident energies of 20, 22, and 24 MeV for 2 or 6 h. The targets were processed to recover an effective thickness corresponding to approximately 5-MeV energy loss, and the resulting sodium pertechnetate 99mTc was assayed for chemical, radiochemical, and radionuclidic purity. Radioisotopic content in final formulation was quantified using γ-ray spectrometry. The internal radiation dose for 99mTc-pertechnetate was calculated on the basis of experimentally measured values and biokinetic data in humans. Planar and SPECT imaging were performed using thin capillary and water-filled Jaszczak phantoms. Extracted sodium pertechnetate 99mTc met all provisional quality standards. The formulated solution for injection had a pH of 5.0-5.5, contained greater than 98% of radioactivity in the form of pertechnetate ion, and was stable for at least 24 h after formulation. Radioisotopic purity of 99mTc produced with 99.03% enriched 100Mo was greater than 99.0% decay corrected to the end of bombardment (EOB). The radioisotopic purity of 99mTc produced with 99.815% enriched 100Mo was 99.98% or greater (decay corrected to the EOB). The estimated dose increase relative to 99mTc without any radionuclidic impurities was below 10% for sodium pertechnetate 99mTc produced from 99.03% 100Mo if injected up to 6 h after the EOB. For 99.815% 100Mo, the increase in effective dose was less than 2% at 6 h after the EOB and less than 4% at 15 h after the EOB when the target was irradiated at an incident energy of 24 MeV. Image spatial resolution and contrast with cyclotron-produced 99mTc were equivalent to those obtained with 99mTc eluted from a conventional generator. Clinical-grade sodium pertechnetate 99mTc was produced with a cyclotron at medium energies. Quality control procedures and release specifications were drafted as part of a clinical trial application that received approval from Health Canada. The results of this work are intended to contribute to establishing a regulatory framework for using cyclotron-produced 99mTc in routine clinical practice.

Quantitative analysis of relationships between irradiation parameters and the reproducibility of cyclotron-produced 99mTc yields

Cyclotron production of 99mTc through the 100Mo(p,2n) 99mTc reaction channel is actively being investigated as an alternative to reactor-based 99Mo generation by nuclear fission of 235U. An exciting aspect of this approach is that it can be implemented using currently-existing cyclotron infrastructure to supplement, or potentially replace, conventional 99mTc production methods that are based on aging and increasingly unreliable nuclear reactors. Successful implementation will require consistent production of large quantities of high-radionuclidic-purity 99mTc. However, variations in proton beam currents and the thickness and isotopic composition of enriched 100Mo targets, in addition to other irradiation parameters, may degrade reproducibility of both radionuclidic purity and absolute 99mTc yields. The purpose of this article is to present a method for quantifying relationships between random variations in production parameters, including 100Mo target thicknesses and proton beam currents, and reproducibility of absolute 99mTc yields (defined as the end of bombardment (EOB) 99mTc activity). Using the concepts of linear error propagation and the theory of stochastic point processes, we derive a mathematical expression that quantifies the influence of variations in various irradiation parameters on yield reproducibility, quantified in terms of the coefficient of variation of the EOB 99mTc activity. The utility of the developed formalism is demonstrated with an example. We show that achieving less than 20% variability in 99mTc yields will require highly-reproducible target thicknesses and proton currents. These results are related to the service rate which is defined as the percentage of 99mTc production runs that meet the minimum daily requirement of one (or many) nuclear medicine departments. For example, we show that achieving service rates of 84.0%, 97.5% and 99.9% with 20% variations in target thicknesses requires producing on average 1.2, 1.5 and 1.9 times the minimum daily activity requirement. The irradiation parameters that would be required to achieve these service rates are described. We believe the developed formalism will aid in the development of quality-control criteria required to ensure consistent supply of large quantities of high-radionuclidic-purity cyclotron-produced 99mTc.

Reexamination of cross sections of the 100Mo(p,2n)99mTc reaction

The nuclear medicine community has been expressing concerns world wide regarding shortages of 99mTc supply based on fission production of 99Mo from highly enriched uranium (HEU) to prepare 99Mo/99mTc generators. As an alternative to reactor produced 99Mo/99mTc generator technology, the direct production of 99mTc on accelerators is considered. There are a number of methods of using accelerators to produce 99mTc and/or 99Mo. Direct production of 99mTc on highly enriched 100Mo target using cyclotrons is interesting for energies up to 20MeV, so as to minimize the impurities from additional open reaction channels. To estimate the quality of the accelerator produced 99mTc all the possible reaction routes should be mapped which could be potentially involved in this technology. However, a well defined excitation function for the 100Mo(p,2n)99mTc primary reaction is needed, in order to achieve acceptable good results in assessing the quality of the accelerator-produced 99mTc by theoretical calculations. Most of the available experimental cross section data series for the 100Mo(p,2n)99mTc reaction have the same general shape while their amplitudes are different. A large difference more than a factor of two may, indeed, be observed between the lowest and the highest datasets values.The aim of this study was therefore to get a new evaluation for the 100Mo(p,2n)99mTc cross section, through three independent experiments, aiming at a more confident estimation about the amplitude of the excitation function.