Abstract
The concept of theranostics in nuclear medicine is based on the use of a pair of radioisotopes to label radiopharmaceuticals for both diagnosis and therapy and is essential for nuclear ...medicine developments. The production of novel medical radioisotopes using solid target stations is challenging and new instruments and methods are needed. A research program is ongoing at the 18 MeV Bern medical cyclotron, equipped with a Solid Target Station and a 6.5 m Beam Transfer Line ending in a separate bunker. To irradiate isotope-enriched materials in form of compressed powder pellets, a novel target coin was conceived and realized together with methods to assess the beam energy and the production cross sections. To optimize the irradiation procedure, a novel ultra-compact active irradiation system based on a specific magnetic lens and a two-dimensional beam detector was conceived, constructed and tested. The system allows to control on-line the size and position of the beam and to correct its characteristics by steering and focusing it in order to keep it on target. The first results on the production of several radionuclides (
43
Sc,
44
Sc,
47
Sc,
61
Cu,
64
Cu,
67
Cu,
68
Ga,
165
Er,
165
Tm,
167
Tm and
155
Tb) are presented.
Underground-produced 37Ar can be used for underground nuclear explosions (UNE) detection and for groundwater dating. The quantification of the emanation, that is the fraction of activity produced in ...the rock that escapes to the pore space, is essential for predicting the background activity expected in natural environments. We propose an experiment in which artificial CaCO3 powder and natural rock particles are irradiated with neutrons in a routinely operated medical cyclotron, whose energy spectrum is experimentally measured. The produced activity was quantified and compared with the emanated activity to determine the emanating fraction. The results showed consistent and reproducible patterns with a dominance of the recoil process at small scales (<2 mm). We observed emanation values ≤1% with a dependency on the grain size and the inner geometry of particles. Soil weathering and the presence of water increased the recoil emanation. The atoms produced that were instantaneously recoiled in the intra- or inter-granular pore space left macroscopic samples by diffusion on timescales of days to weeks (Deff = 10−12 – 10−16 m2 s−1). This diffusive transport determines the activity that prevails in the fluid-filled pore space accessible for groundwater or soil gas sampling.
•37Ar emanation was assessed in irradiated natural rocks using neutrons from a medical cyclotron.•The neutron spectrum was measured with an innovative neutron spectrometer named DIAMON.•Emanation in nature consists of instantaneous recoil followed by diffusive transport.•Soil weathering processes increase the emanation close to the surface.•Porous water increases recoil but impedes diffusion, resulting in a lower total emanation.
A novel fiber-optic beam monitor Usherovich, S.; Casolaro, P.; Gottstein, A. ...
Journal of physics. Conference series,
01/2024, Letnik:
2687, Številka:
7
Journal Article
Recenzirano
Odprti dostop
Abstract
A novel beam monitor based on Ce-doped silica optical fibers is being presented. Four fibers are mounted on the outside of a beam transport pipe, at the location of a beam stop at a proton ...cyclotron. The secondary radiation caused by the proton beam interaction with the beam stop is measured by the optical fibers via Radiation-Induced Emission (RIE). The light signal in the individual fibers is correlated to the proton flux closest to the fiber and can therefore be used as a detector to monitor the position of the proton beam in the beam stop. Initial testing shows that monitoring of a 150 nA beam of 18 MeV protons into a beam dump is possible. The monitor can measure relative beam current and beam displacement in X and Y as a function of magnetic steering.
During the operational life of a PET cyclotron, the concrete walls of the vault are activated by secondary neutrons. For the dismantling of such accelerator facilities, a considerable amount of low ...level solid radioactive waste has to be characterized and disposed. To decrease future dismantling costs and complexity, the amount of radioactive waste has to been prospectively evaluated in the design phase, then confirmed at the time of planning decommissioning. In this work, the Monte Carlo code Fluka was used for the assessment of the activation of the bunkers of two different facilities: the 16.5 MeV GE PETtrace at S. Orsola-Malpighi Hospital in Bologna and the 18 MeV IBA Cyclone 18/18 HC at the Bern University Hospital (Inselspital). The simulations were validated by means of experimental measurements performed in our previous works: non-destructive, in field measurements using a portable CZT detector were performed in Bologna; while core drilling samples were extracted from the bunker and measured in laboratory with an HPGe detector in Bern. The activity of the most important radionuclides in the concrete walls of the bunker, namely Eu-152, Mn-54, Co-60, Sc-46, Zn-65 and Cs-134 resulted within the range of 0.01 – 2 Bq/g. The consistency between Monte Carlo results and experimental measurements was within a factor 2 - 3 for most radionuclides, except for Eu-152, Sc-46, Zn-65. The activity concentrations estimated at each position considered exceeds the clearance levels of the new Directive 2013/59/Euratom.
The results of this work demonstrate that Monte Carlo simulations based on FLUKA are adequate to assess the residual activation levels, a fundamental information to foresee, plan and optimize the decommissioning of a cyclotron based PET centers.
•The activation in PET cyclotron bunkers was assessed via Monte Carlo simulations.•The Monte Carlo code used in this work was Fluka.•The model of a GE PETtrace and a IBA CYCLONE with their bunkers was implemented.•Monte Carlo simulation results were compared with experimental measurements.•The main long lived radionuclides produced were assessed.
Background
Terbium-155 T
1/2
= 5.32 d, Eγ = 87 keV (32%) 105 keV (25%) is an interesting radionuclide suitable for single photon emission computed tomography (SPECT) imaging with potential ...application in the diagnosis of oncological disease. It shows similar decay characteristics to the clinically established indium-111 and would be a useful substitute for the diagnosis and prospective dosimetry with biomolecules that are afterwards labeled with therapeutic radiolanthanides and pseudo-radiolanthanides, such as lutetium-177 and yttrium-90. Moreover, terbium-155 could form part of the perfect “matched pair” with the therapeutic radionuclide terbium-161, making the concept of true radiotheragnostics a reality. The aim of this study was the investigation of the production of terbium-155 via the
155
Gd(p,n)
155
Tb and
156
Gd(p,2n)
155
Tb nuclear reactions and its subsequent purification, in order to obtain a final product in quantity and quality sufficient for preclinical application. The
156
Gd(p,2n)
155
Tb nuclear reaction was performed with 72 MeV protons (degraded to ~ 23 MeV), while the
155
Gd(p,n)
155
Tb reaction was degraded further to ~ 10 MeV, as well as performed at an 18 MeV medical cyclotron, to demonstrate its feasibility of production.
Result
The
156
Gd(p,2n)
155
Tb nuclear reaction demonstrated higher production yields of up to 1.7 GBq, however, lower radionuclidic purity when compared to the final product (~ 200 MBq) of the
155
Gd(p,n)
155
Tb nuclear reaction. In particular, other radioisotopes of terbium were produced as side products. The radiochemical purification of terbium-155 from the target material was developed to provide up to 1.0 GBq product in a small volume (~ 1 mL 0.05 M HCl), suitable for radiolabeling purposes. The high chemical purity of terbium-155 was proven by radiolabeling experiments at molar activities up to 100 MBq/nmol. SPECT/CT experiments were performed in tumor-bearing mice using
155
TbTb-DOTATOC.
Conclusion
This study demonstrated two possible production routes for high activities of terbium-155 using a cyclotron, indicating that the radionuclide is more accessible than the exclusive mass-separated method previously demonstrated. The developed radiochemical purification of terbium-155 from the target material yielded
155
TbTbCl
3
in high chemical purity. As a result, initial cell uptake investigations, as well as SPECT/CT in vivo studies with
155
TbTb-DOTATOC, were successfully performed, indicating that the chemical separation produced a product with suitable quality for preclinical studies.
The future development of personalized nuclear medicine relies on the availability of novel medical radionuclides. In particular, radiometals are attracting considerable interest since they can be ...used to label both proteins and peptides. Among them, the β+-emitter 68Ga is widely used in nuclear medicine for positron emission tomography (PET). It is used in theranostics as the diagnostic partner of the therapeutic β−-emitters 177Lu and 90Y for the treatment of a wide range of diseases, including prostate cancer. Currently, 68Ga is usually obtained via 68Ge/68Ga generators. However, their availability, high price and limited produced radioactivity per elution are a major barrier for a wider use of the 68Ga-based diagnostic radiotracers. A promising solution is the production of 68Ga by means of proton irradiation of enriched 68Zn liquid or solid targets. Along this line, a research program is ongoing at the Bern medical cyclotron, equipped with a solid target station. In this paper, we report on the measurements of 68Ga, 67Ga and 66Ga production cross-sections using natural Zn and enriched 68Zn material, which served as the basis to perform optimized 68Ga production tests with enriched 68Zn solid targets.
•Measurement of Ga radioisotope cross-sections by irradiating natZn and enr−68Zn.•Measurements performed using a beam transfer line and an 18 MeV medical cyclotron.•The thick target production yields and purities were studied.•Production tests were performed using a solid target station.•An 18 MeV cyclotron is suitable to produce 68Ga for PET imaging in nuclear medicine.
Radioisotopes for theranostics are essential for nuclear medicine developments. Their production using solid target stations is challenging and new instruments and methods derived from particle ...physics are needed. A research program is ongoing at the 18 MeV Bern medical cyclotron, equipped with a solid target station and a 6 m long beam transfer line ending in a separate bunker. To irradiate 6 mm diameter compressed powder pellets, novel target “coins” were conceived and realized together with methods to assess the beam energy and the production cross sections. To measure the activity at End of Beam (EoB) a system based on a CdZnTe detector was installed. To accurately assess the properties of the beam, novel non-destructive one- and two-dimensional beam monitoring detectors were developed. An ultra-compact active irradiation system based on a novel magnetic lens and two-dimensional beam detectors was conceived and tested with the beamline and recently installed in an outport of the cyclotron.
Accelerators for hadrontherapy: From Lawrence cyclotrons to linacs Amaldi, U.; Bonomi, R.; Braccini, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2010, Letnik:
620, Številka:
2
Journal Article
Recenzirano
Hadrontherapy with protons and carbon ions is a fast developing methodology in radiation oncology. The accelerators used and planned for this purpose are reviewed starting from the cyclotrons used in ...the thirties. As discussed in the first part of this paper, normal and superconducting cyclotrons are still employed, together with synchrotrons, for proton therapy while for carbon ion therapy synchrotrons have been till now the only option. The latest developments concern a superconducting cyclotron for carbon ion therapy, fast-cycling high frequency linacs and ‘single room’ proton therapy facilities. These issues are discussed in the second part of the paper by underlining the present challenges, in particular the treatment of moving organs.
PDF
