Cyclotron Facility Research Articles

Measurement of production cross sections of 66,67Ga, 65Zn and 57,58Co from alpha induced reactions of natural copper for energy up to 50 MeV utilizing cyclotron facility at VECC

Excitation functions of 66,67Ga and 65Zn, generally used for beam intensity monitoring and/or beam energy determination; 57Co and 58Co produced by natCu(α,x) reactions were measured from their respective thresholds up to 50 MeV using standard stacked foil activation technique followed by high resolution gamma ray spectrometric method. Thick target yields were calculated for these radionuclides using the experimentally determined cross sections and stopping power of natural Cu. Experimentally obtained results were compared with the recently published data, IAEA recommended data and TENDL-2019 data based on the TALYS-1.95 code. The present data are found to be in good agreement with the literature data within experimental uncertainties.

Cyclotron-produced neutrons measurements using chlorine activation

Certain proton reactions emit fast neutrons, and this study examines the feasibility of measuring the neutrons emitted from a typical medical 18 MeV proton cyclotron using prompt gamma neutron activation on chlorine. This neutron detection method, employed by previous studies, has been deemed successful and highly promising. The measurement system includes a gamma radiation scintillator, for example NaI(Tl), with a spectrometry setup facing a convertor that contains a chlorine solution or compounds thereof.In its natural state, elemental chlorine is a chemically unstable gas, making its use as a convertor challenging. Therefore, chlorine is usually dissolved in solutions. Such solutions are diluted with water and contain hydrogen atoms that interact intensively with the neutrons and may interrupt their detection.Accordingly, in this study, a 25.5 L container of KCl powder was placed in front of a NaI(Tl) (7.62 cm diameter by 7.62 cm length) spectrometer near a cyclotron facility. The gamma radiation spectroscopy allowed the identification of the chlorine INS gamma line at 788 keV, alongside the K-40 gamma peak. In addition, it was possible to detect the fast neutrons using a total-counting mode, when the INS counts appear above the K-40 counting level.The chlorine INS peak in the KCl convertor was detected simultaneously during the cyclotron operations and provided a direct indication of neutron exposure around the cyclotron. We conclude that using KCl as a converter, with a NaI(Tl) gamma rays counter, is successful in detecting cyclotron-produced neutron emissions.

Assessment of the Second-Ionization Potential of Lawrencium: Investigating the End of the Actinide Series with a One-Atom-at-a-Time Gas-Phase Ion Chemistry Technique.

Experiments were performed at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron facility to investigate the electron-transfer reduction reaction of dipositive Lr (Z = 103) with O2 gas. Ions of 255Lr were produced in the fusion-evaporation reaction 209Bi(48Ca,2n) 255Lr and were studied with a novel gas-phase ion chemistry technique. The produced 255Lr2+ ions were trapped and O2 gas was introduced, such that the charge-exchange reaction to reduce 255Lr2+ to 255Lr1+ was observed and the reaction rate constant was determined to be k = 1.5(7) × 10-10 cm3/mol/s. The observation that this reaction proceeds establishes the lower limit on the second ionization potential of Lr to be 13.3(3) eV. This gives further support that the actinide series terminates with Lr. Additionally, this result can be used to better interpret the situation concerning the placement of Lu and Lr on the periodic table within the current framework of the actinide hypothesis. The success of this experimental approach now identifies unique opportunities for future gas-phase reaction studies on actinide and super heavy elements.

ESTIMATION OF THERMAL & EPITHERMAL NEUTRON FLUX AND GAMMA DOSE DISTRIBUTION IN A MEDICAL CYCLOTRON FACILITY FOR RADIATION PROTECTION PURPOSES USING GOLD FOILS AND GATE 9.

The aim of this study is to characterise the neutron flux generated directly behind targets used in medical cyclotrons. The characterisation process aims at determining the feasibility of using the generated neutrons for research purposes in neutron activation analysis. The study was performed by activating gold foils placed directly behind the cyclotron targets. The thermal and epithermal neutron flux were found to be 4.5E+05±8.78E+04neutronscm-2s-1 and 2.13E+06±8.59E+04neutronscm-2s-1, respectively. The flux value is the same order of magnitude listed in the manual produced by the cyclotron manufacturer. The results are encouraging and show high potential for using the cyclotron facility as a thermal neutron source for research purposes. However, it is important radiation protection procedures be followed to ensure the safety of researchers due to the high gamma dose rate measured directly behind the target at 2.46Sv/h using an OSL chip during the beam on time.

Measurement of 59Co(n, x) reaction cross sections with the fast neutrons based on the 9Be(p, n) reaction * *Partly supported by the National Research Foundation of Korea (NRF) through a grant provided by the Ministry of Science and ICT (NRF-2017R1D1A1B03030484, NRF-2013M7A1A1075764, NRF-2018R1A6A1A06024970)

The cross sections of the 59Co(n, x) reaction in the average energy range of 15.2-37.2 MeV were measured using activation and an off-line γ-ray spectrometric technique. The neutrons were generated from the 9Be(p, n) reaction with proton beam energies of 25-45 MeV at the MC-50 Cyclotron facility of the Korean Institute of Radiological and Medical Sciences (KIRAMS). Theoretical calculations of neutron–induced reactions on 59Co were performed using the nuclear model code TALYS-1.9. The results for the 59Co(n, x) reactions were compared with the theoretical values obtained using TALYS-1.9 and the literature data provided in EXFOR and the TENDL 2019 nuclear data library. The theoretical values obtained using TALYS-1.9 with adjusted parameters are comparable to the experimental data. The measured reaction cross sections of a few radionuclides are new, and the others are comparable to the literature data, and thus, they can strengthen the database. The present study on cross sections leads to useful insight into the mechanisms of 59Co(n, x) reactions.

Experience and Challenges during Establishment of a Cyclotron and PET-CT facility at National Institute of Nuclear Medicine & Allied Sciences (NINMAS)

Abstract not available
 Bangladesh J. Nuclear Med. 22(2): 137-140, Jul 2019

Cyclotron for PET: System Upgrade after 13 Years of Service

Compact cyclotrons aimed at producing radioisotopes in the hospital environment play a crucial role in the progress of nuclear medicine. Obtaining beams with the current higher than 150 μA and kinetic energy of approximately 20 MeV requires design efforts in terms of stability, radiofrequency (RF), and field shape. The optimization procedure along with the commissioning phase is vital, as well as regular precautionary maintenance in order to guarantee high performance. Since the request of radionuclide users on the beam intensity has increased, we have decided to improve the cyclotron facility (e.g., dual proton source, helium cooling system, RF system, new 11C target and 18F target installation, etc.) at Cannizzaro Hospital. The progress of the cyclotron facility upgrade is presented in this paper.

Radiological analysis for radioactivity depth distribution in activated concrete using gamma-ray spectrometry

In this research, in-situ measurement methods to analyze the radioactivity depth distribution were developed by measuring 152Eu emitted from activated concrete used the Peak to Compton (PTC) method using a high-purity germanium (HPGe) detector. The experimental results of various radioactivity depth distributions agree within 3% relative error with the results of an MCNP simulation. The correlation between the values obtained with the PTC method and the radioactivity depth distribution was derived. In order to use the PTC method in the field, the impact of the material composition, surface area, and density change of the measurement target was evaluated by an MCNP simulation. The developed method was applied to activated concrete in cyclotron facilities and the results were compared with the sample analysis, revealing a relative error of less than 20%. The results of this research will be useful in quickly and accurately evaluating the radioactivity depth distribution of activated concrete. Further study should be carried out in order to enable analysis of various forms of radioactivity depth distributions of activated structures in nuclear facilities.

Assessment of personnel absorbed dose at an 18-MeV dual beam cyclotron facility

This study aimed to investigate occupational radiation exposure in cyclotron workers in Saudi Arabia and compare the doses received with the International Commission of Radiological Protection dose limits. We conducted a retrospective study of Hp (10) and Hp (0.07) in 144 workers in an 18-MeV dual beam (proton and deuteron) cyclotron facility in Saudi Arabia from 2015 to 2019. The workers included physicists, engineers, chemists, radiochemists, technicians, operators, and quality control chemists. Individual dosimetry was assessed using thermoluminescent dosimeters (TLDs) comprised of Harshaw detector crystals with LiF:Mg, Ti elements. The mean Hp (10) and Hp (0.07) doses averaged over the 5-year study period for all workers were 1.47 ± 0.15 and 1.54 ± 0.16 mSv, respectively. No worker received doses exceeding the annual dose limits. We recommend that workers wear ring dosimeters to estimate the dose to the extremities and dosimeters use an advanced type of absorber to discriminate between different types of radiation.

Pairing of thorium with selected primary target materials in tandem configurations: Co-production of 225Ac/213Bi and 230U/226Th generators with a 70 MeV H[formula omitted] cyclotron

Several radionuclide production facilities based on a new generation of high-current, 70 MeV H− cyclotrons have been established in recent years and a number of new facilities are either under construction or being planned. In this study, the feasibility to produce 225Ac/213Bi and 230U/226Th generators via Th + p reactions at such a facility has been investigated. From the perspective of production yields, it has been found useful to compare the relevant reactions on thorium with those on other targets regularly employed in this energy region, in particular the natMg(p,x)22Na, natGa(p,x)68Ge, and natRb(p,x)82Sr reactions that have been exploited with 66 MeV proton beams at iThemba LABS for many years. Therefore, various tandem configurations of thorium with magnesium, gallium and rubidium are discussed based on the relevant nuclear data. In a few cases, the available data were judged to be insufficient in this energy region. New experimental cross sections are presented for 225Ac, 225Ra, and 230Pa in Th + p reactions as well as 22,24Na in natMg + p reactions. Integral yields have been derived for those radionuclides of main interest. Production yields expected from extended 70 MeV proton bombardments, on selected tandem-target configurations, are presented for 22Na, 68Ge, 82Sr, 225Ac, and 230Pa. It is concluded that 225Ac/213Bi generators can, in principle, be added to a production programme based at a 70 MeV H− cyclotron facility as the production rate is of similar magnitude to those of other well-established radionuclides in this energy region. Also, radio-contaminant levels for 225Ac are similar to those found in higher proton-energy windows. The scope for 230U/226Th generators, via bulk production of the precursor 230Pa, seems to be more limited due to a lower yield but can nevertheless be produced in clinically relevant quantities.

Reactor produced [64Cu]CuCl2 as a PET radiopharmaceutical for cancer imaging: from radiochemistry laboratory to nuclear medicine clinic

Copper-64 is a useful theranostic radioisotope that is attracting renewed interest from the nuclear medicine community in the recent times. This study aims to demonstrate the utility of research reactors to produce clinical-grade 64Cu via 63Cu(n,γ)64Cu reaction and use it in the form of [64Cu]CuCl2 as a radiopharmaceutical for PET imaging of cancer in human patients. Copper-64 was produced by irradiation of natural CuO target in a medium flux research reactor. The irradiated target was radiochemically processed and detailed quality control analyses were carried out. Sub-acute toxicity studies were carried out with different doses of Cu in Wistar rats. The biological efficacy of the radiopharmaceutical was established in preclinical setting by biodistribution studies in melanoma tumor bearing mice. After getting regulatory approvals, [64Cu]CuCl2 formulation was clinically used for PET imaging of prostate cancer and glioblastoma patients. Large-scale (~ 30GBq) production of 64Cu could be achieved in a typical batch and it was adequate for formulation of clinical doses for multiple patients. The radiopharmaceutical met all the purity requirements for administration in human subjects. Studies carried out in animal model showed that the toxicity due to "cold" Cu in clinical dose of [64Cu]CuCl2 for PET scans would be negligible. Clinical PET scans showed satisfactory uptake of the radiopharmaceutical in the primary cancer and its metastatic sites. To the best of our knowledge, this is the first study on use of reactor produced [64Cu]CuCl2 for PET imaging of cancer in human patients. It is envisaged that this route of production of 64Cu would aid towards affordable availability of this radioisotope for widespread clinical use in countries with limited cyclotron facilities.

Large-scale production of 88Y and 88Zr/88Y generators: A proof of concept study for a 70 MeV H[formula omitted] cyclotron

The large-scale production of 88Y with proton-induced reactions has been investigated from the perspective of new generation 70 MeV H− cyclotrons. Tandem target configurations are presented for both the direct production of 88Y as well as for producing 88Zr/88Y generators. Based on the relevant excitation functions, physical yields have been derived for 88Y production with Y2O3/SrCO3 tandem targets and 88Zr production with Zr/Y2O3 tandem targets. Yields are presented for optimized targets (i.e. optimum yield) as well as for balanced thermal loads on the individual targets. Liquid 88Zr/88Y generators have been produced using both natural Zr and Nb target materials, the former for dedicated productions and the latter as a byproduct by processing spent irradiated Nb capsules which normally would constitute radioactive waste. These stock solutions, which contain both the target material and 88Zr precursor, are retained virtually unchanged after processing except for the removal of 88Y on AG MP-50 macroporous cation-exchange resin. Methods are presented for the preparation of Nb stock solutions in hydrofluoric acid and Zr stock solutions in sulphuric acid. It is shown that multi-Ci productions of 88Y are feasible at a 70 MeV cyclotron facility, suitable for the needs of fracking applications. In addition, 88Zr/88Y generators can provide 88Y with very high specific activity, suitable for labelling of biomolecules. LA-UR-20-24305.

Assessment of radionuclide impurities in [18F]fluoromethylcholine ([18F]FMCH).

[18F]Fluoromethylcholine ([18F]FMCH) is a radiopharmaceutical used in positron emission tomography (PET) imaging for the study of prostate, breast, and brain tumors. It is usually synthesized in cyclotron facilities where 18F is produced by proton irradiation of [18O]H2O through 18O(p,n)18F reaction. Due to the activation of target materials, the bombardment causes unwanted radionuclidic impurities in [18O]H2O, that need to be removed during the radiopharmaceutical synthesis. Thus, the aim of this study is to quantify the radionuclide impurities in the 18F production process and in the synthesized [18F]FMCH, demonstrating the radionuclidic purity of this radiopharmaceutical. Long-lived radionuclide impurities were experimentally assessed using high-resolution gamma and liquid scintillation spectrometries, while short-lived impurities were monitored analyzing the decay curve of the irradiated [18O]H2O with an activity calibrator. As spectrometric radionuclide library, a Geant4 Monte Carlo simulation of the 18F-target assembly was previously performed. 3H, 52,54Mn, 56,57,58Co, 95m,96Tc, 109Cd, and 184Re were found in the irradiated [18O]H2O, but no radionuclide was found in the non-irradiated [18O]H2O neither in the final [18F]FMCH solution with an activity concentration greater than the minimum detectable activity concentration. A total impurity activity<6.2kBq was measured in the irradiated [18O]H2O, whereas a [18F]FMCH radionuclide purity>99.9999998% was estimated. Finally, the decay curve of the irradiated [18O]H2O revealed a very low maximum of 13N activity (<0.03% of 18F) even immediately after the end of bombardment. This study demonstrated the radionuclidic purity of [18F]FMCH according to the EU Pharmacopeia.

Beamline characterization of a dielectric-filled reentrant cavity resonator as beam current monitor for a medical cyclotron facility.

At PSI (Paul Scherrer Institute), Switzerland, a superconducting cyclotron called "COMET" delivers proton beam of 250MeV pulsed at 72.85MHz for proton radiation therapy. Measuring proton beam currents (0.1-10nA) is of crucial importance for the treatment safety and is usually performed with invasive monitors such as ionisation chambers (ICs) which degrade the beam quality. A new non-invasive beam current monitor working on the principle of electromagnetic resonance is built to replace ICs in order to preserve the beam quality delivered. The fundamental resonance frequency of the resonator is tuned to 145.7MHz, which is the second harmonic of the pulse rate, so it provides signals proportional to beam current. The cavity resonator installed in the beamline of the COMET is designed to measure beam currents for the energy range 238-70MeV. Good agreement is reached between expected and measured resonator response over the energy range of interest. The resonator can deliver beam current information down to 0.15nA for a measurement integration time of 1s. The cavity resonator might be applied serving as a safety monitor to trigger interlocks within the existing domain of proton radiation therapy. Low beam currents limit the abilities to detect sufficiently, however, with the potential implementation of FLASH proton therapy, the application of cavity resonator as an online beam-monitoring device is feasible.

A Cyclotron Decommissioning Radiological Assessment Exercise Performed by Student Mentees Underrepresented in the Radiation Safety Profession.

Cyclotrons used in nuclear medicine imaging accelerate protons, deuterons, and helium ions to bombard a target, which produces nuclear reactions that generate positron-emitting radionuclides. Secondary neutrons are nonuniformly emitted in these reactions and induce heterogeneous activation of the cyclotron components and concrete vault enclosure. This poses radioactive waste management complications when decommissioning a cyclotron facility, since the objective is to ensure that exposures are within regulatory limits and as low as reasonably achievable (ALARA). The McGovern Medical School in The University of Texas Health Science Center in Houston housed a Scanditronix MC40 cyclotron that produced short-lived radioisotopes for Positron Emission Tomography (PET) imaging from 1984 to 2001 until Tropical Storm Allison rendered it inoperable. The purpose of this study was to provide underrepresented Science, Technology, Engineering and Mathematics (STEM) students an ALARA experience with a practical problem encountered in the radiation safety profession. Gamma dose rate measurements were performed with both a Mirion InSpector 1000 spectrometer and Fluke 451P survey meter in the vault at locations identified as hotspots based on preliminary scoping surveys with the Ludlum model 44-9 detector. However, gamma spectra were measured with the spectrometer exclusively at hotspots along the west wall. Results indicated the maximum gamma dose rate of 129 ± 31 nSv h was about 2 times background near the central beam transport line of the now inoperable cyclotron. Furthermore, gamma emission peaks were identified in the spectra from trace amounts of Co and Eu in the vault's concrete walls.

Gamma-ray measurements of the activated target components in a cyclotron used for positron emission tomography

The proton irradiation in a PET cyclotron produces radioactive by-products with high levels of activity in the target components, which are strongly dependent on the specific parameters used in the cyclotron facility. Because the target assembly parts must be replaced periodically, external exposure to operators must be assessed. In this work, high-resolution gamma-ray spectrometry was used to determine the activity levels for the specific radionuclides induced in the target components of a medical 9.6 MeV MINItrace cyclotron. The focus was on three target components, which are periodically replaced: Havar foil, Titanium foil and the Helicoflex seal located on the path of the proton beam just in front of the silver vessel containing the enriched water. Eight radionuclides were identified in the Havar foil: 54Mn, 56Co, 57Co, 58Co, 60Co, 95Tc, 109Cd and 183Re. In the titanium foil, the nuclides 46Sc, 48V, 51Cr, 56Co, 57Co, and 75Se were identified, while only 51Cr, 58Co, and 60Co were detected in the Helicoflex seal. The total effective dose rates to which staff are exposed at the moment of replacing the target were calculated. The waste management for these target components was also considered, using the half-lives of the detected radionuclides in order to determine the time necessary for the activity levels in the target components to be below the exemption levels recommended by the IAEA.

NEW TARGET ASSEMBLY FOR SOLID SAMPLES IRRADIATION IN 11-MeV MEDICAL CYCLOTRON

In this work we present the new target assembly developed for solid samples irradiation by protons with different energies at maximum of 11 MeV and 40 μA for current. The new target was designed and manufactured for conventional target changer (carousel) of 11 MeV Eclipse RD medical cyclotron. The MCNP simulation of the beam profile after degradation was performed and testing irradiation of the target assembly was successfully carried out showing the target suitability for such type of cyclotron facilities.

Realizing Clinical Trials with Astatine-211: The Chemistry Infrastructure.

Despite the consensus around the clinical potential of the α-emitting radionuclide astatine-211 (211At), there are only a limited number of research facilities that work with this nuclide. There are three main reasons for this: (1) Scarce availability of the nuclide. Despite a relatively large number of globally existing cyclotrons capable of producing 211At, few cyclotron facilities produce the nuclide on a regular basis. (2) Lack of a chemical infrastructure, that is, isolation of 211At from irradiated targets and the subsequent synthesis of an astatinated product. At present, the research groups that work with 211At depend on custom systems for recovering 211At from the irradiated targets. Setting up and implementing such custom units require long lead times to provide a proper working system. (3) The chemistry of 211At. Compared with radiometals there are no well-established and generally accepted synthesis methods for forming sufficiently stable bonds between 211At and the tumor-specific vector to allow for systemic applications. Herein we present an overview of the infrastructure of producing 211At radiopharmaceuticals, from target to radiolabeled product including chemical strategies to overcome hurdles for advancement into clinical trials with 211At.

Preparation of a radiobiology beam line at the 18 MeV proton cyclotron facility at CNA

Proton therapy has gained interest in recent years due to its excellent clinical outcomes. However, the lack of accurate biological data, especially in the Bragg peak region of clinical beams, makes it difficult to implement biophysically optimized treatment plans in clinical practice. In this context, low energy proton accelerator facilities provide the perfect environment to collect good radiobiological data, as they can produce high LET beams with narrow energy distributions. This study presents the radiobiology beam line that has been designed at the 18 MeV proton cyclotron facility at the National Centre of Accelerators (CNA, Seville, Spain), to perform irradiations of mono-layer cell cultures. To ensure that all the cells receive the same dose with a suitable dose rate, low beam intensities and broad and homogeneous beam profiles are necessary. To do so, at the CNA an unfocused beam has been used, broadened with a 500 μm thick aluminium scattering foil. Homogeneous dose profiles, with deviations lower than 10% have been obtained over a circular surface of 35 mm diameter for an incident average energy of 12.8 MeV. Further, a Monte Carlo simulation of the beam line has been developed with Geant4, and benchmarked towards experimental measurements, with differences generally below 1%. Once validated, the code has been used, together with an ionization chamber, for dosimetry studies, to characterize the beam and monitor the dose. Finally, cultures of Human Bone Osteosarcoma cells (U2OS) have been successfully irradiated at the radiobiology beam line, investigating the effects of radiation in terms of DNA damage induction.

Study of the magnet for 1 MeV cyclotron

The cyclotron is a circular particle accelerator. It was invented by Lawrence and Livingston in 1932. Currently, at least 4 cyclotrons are operating in Malaysia with the energy range of 8.5 MeV to 18 MeV. Typically, those cyclotron facilities are used for the medical radioisotope production. The potential of cyclotron with its applications has embarked us to the conceptual design of 1 MeV Cyclotron. Magnet as an essential component of Cyclotron to guide the beam into the circular desired orbit. Therefore, this paper will discuss the design of this magnet for 1 MeV Cyclotron by using different structure of magnet yoke with the aim to achieve a uniform fringe magnetic field of 1.7 Tesla. As the result, the profile at the median plane of the air gap and the characteristic of edge focusing is simulated by using the 2D Finite Element Method Magnetics (FEMM 4.2) software.