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Pola A, Bortot D, Pasquato S, Mazzucconi D, Chiesa C, Zanellati F, Brusa A. Decommissioning of a Medical Cyclotron Vault: the Case Study of the National Cancer Institute of Milano. Health Phys 2024:00004032-990000000-00130. [PMID: 38394553 DOI: 10.1097/hp.0000000000001801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/25/2024]
Abstract
ABSTRACT In the widespread use of medical cyclotrons for isotope production, radiological and economic consequences related to the decommissioning of particle accelerators are often neglected. However, decommissioning regulation and its related procedures always demand efforts and costs that can unexpectedly impact on budgets. The magnitude of this impact depends strongly on the residual radioactivity of the accelerator and of the vault, and more specifically on the kind and activity concentration of residual radionuclides. This work reports and discusses a case study that analyzes in detail the characterization activities needed for optimized management of the decommissioning of a medical cyclotron vault. In particular, this paper presents the activities carried out for assessing the activity concentrations and for guiding the disposal of the cyclotron vault of the Italian National Cancer Institute of Milano (INT). An unshielded 17 MeV cyclotron vault was characterized by high resolution gamma-ray spectrometry both in-situ and in-laboratory on extracted samples. Monte Carlo simulations were also carried out to assess the overall distribution of activation in the vault. After a few months from the final shutdown of the accelerator, activity concentrations in the concrete walls due to neutron activation exceeded the clearance levels in many regions, especially close to the cyclotron target. Due to the relatively long half-lives of some radionuclides, a time interval of about 20 y after the end of bombardment is necessary for achieving clearance in some critical positions. Far from the target or in positions shielded by the cyclotron, activation levels were below the clearance level. The comparison between Monte Carlo simulations and experimental results shows a good agreement. The in-situ measurements, simpler and economically advantageous, cannot completely replace the destructive measurements, but they may limit the number of required samples and consequently the decommissioning costs. The methodology described and the results obtained demonstrated that it is possible to obtain accurate estimations of activity concentrations with cheap and quick in-situ measurements if the concentration profile in-depth inside the wall is well known. This profile can be obtained either experimentally or numerically through suitably validated Monte Carlo simulations.
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Affiliation(s)
- Andrea Pola
- Politecnico di Milano - Dipartimento di Energia, via La Masa 34, 20156, Milano, Italy
| | - Davide Bortot
- Politecnico di Milano - Dipartimento di Energia, via La Masa 34, 20156, Milano, Italy
| | - Stefano Pasquato
- Politecnico di Milano - Dipartimento di Energia, via La Masa 34, 20156, Milano, Italy
| | - Davide Mazzucconi
- Politecnico di Milano - Dipartimento di Energia, via La Masa 34, 20156, Milano, Italy
| | - Carlo Chiesa
- Nuclear Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori di Milano, Via Venezian 1, 20133, Milano, Italy
| | - Fabio Zanellati
- Radiation protection unit, Fondazione IRCCS Istituto Nazionale dei Tumori di Milano, Via Venezian 1, 20133, Milano, Italy
| | - Anna Brusa
- Radiation protection unit, Fondazione IRCCS Istituto Nazionale dei Tumori di Milano, Via Venezian 1, 20133, Milano, Italy
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Bonvin V, Bochud F, Theis C, Vincke H, Damet J, Geyer R. A combined approach for the calculation of activation yields and the characterization of materials for a medical cyclotron. Appl Radiat Isot 2024; 204:111116. [PMID: 38091906 DOI: 10.1016/j.apradiso.2023.111116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 10/31/2023] [Accepted: 11/18/2023] [Indexed: 12/31/2023]
Abstract
Cyclotrons for the production of radiopharmaceuticals have become important tools in modern nuclear medicine. At the end of their lifecycles, such installations have to be dismantled and any activated materials must be treated according to the local radiation protection legislation. Using a simulation model, we have developed a non-destructive approach for the radiological characterization of components inside and around an IBA Cyclone 18/9 cyclotron. The methodology is based on software tools developed at CERN (FLUKA Monte Carlo code, ActiWiz and RAW). The simulation results were compared to measurements made using reference samples placed around the cyclotron inside the bunker. Results show a reasonable agreement between simulation and measurements of about a factor of two for a set of 27 reference samples and 11 radionuclides of interest. The origin of this factor has been thoroughly evaluated and opened the door to further investigations leading to possible avenues for improvement.
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Affiliation(s)
- V Bonvin
- European Council for Nuclear Research (CERN), Esplanade des Particules, CH-1211, Meyrin, Switzerland; Institute of Radiation Physics, Lausanne University Hospital and University of Lausanne, Rue Du Grand-Pré 1, CH-1007, Lausanne, Switzerland.
| | - F Bochud
- Institute of Radiation Physics, Lausanne University Hospital and University of Lausanne, Rue Du Grand-Pré 1, CH-1007, Lausanne, Switzerland
| | - C Theis
- European Council for Nuclear Research (CERN), Esplanade des Particules, CH-1211, Meyrin, Switzerland
| | - H Vincke
- European Council for Nuclear Research (CERN), Esplanade des Particules, CH-1211, Meyrin, Switzerland; University of Technology, Rechbauerstraße 12, 8010, Graz, Austria
| | - J Damet
- Institute of Radiation Physics, Lausanne University Hospital and University of Lausanne, Rue Du Grand-Pré 1, CH-1007, Lausanne, Switzerland; University of Otago, 2 Riccarton Ave, Christchurch, New Zealand
| | - R Geyer
- European Council for Nuclear Research (CERN), Esplanade des Particules, CH-1211, Meyrin, Switzerland; Institute of Radiation Physics, Lausanne University Hospital and University of Lausanne, Rue Du Grand-Pré 1, CH-1007, Lausanne, Switzerland
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