Introduction: In a medical cyclotron facility, Argon-41 (t½ = 109.34m) is produced by the activation of air due to neutron flux during the production of PET radionuclides, according to the 40Ar(n,γ)41Ar reaction. While theoretical estimations of the Argon-41 production have been published, no data were given on experimental measurements. In this work we describe a sampling methodology and report the results of an extensive measurements campaign . Materials and Methods: In order to measure Argon-41 activity, air samples were taken inside the cyclotron bunker and at the stack of the cyclotron bunker in a modified Marinelli-beaker during the routine production of 18F and 11C. The 1000 cm3 Marinelli-beaker was provided with two valves, in order to allow air flow and connection to a pump. Samples analysis was performed in gamma-ray spectrometry system equipped with HPGe detector. The spectrometer was calibrated with a certified water solution and correction factors for sample density were evaluated using the Labsocs software. Routine production of the PET radionuclides were performed with a 16.5 MeV GE-PETtrace cyclotron; the ventilation rate inside the bunker was varied between 0 and about 15 air changes per hour. Results and Conclusions: The saturation yield of 41Ar production in the air of the bunker with no ventilation resulted to be 3.4 ± 0.3 (Bq/l)/μA. The amount of radioactivity released in the environment depends on many parameters, such as the irradiation duration, the integrated current, the ventilation rates etc. The peak activity concentration of Argon-41 in the exhaust during routine 18F production was 1.4 ± 0.5 Bq/l in dual beam irradiations with a beam current of 80 μA, while for 11C production peak activity concentration resulted to be 0.8 ± 0.2 Bq/l in single beam irradiations at 70 μA. These results confirm that the average activity concentration in the air released in external environment by a PET cyclotron centre can be maintained under the limit of radiological relevance. References: 1. C. Birattari, M. Bonardi, A. Ferrari, M. Silari. Radiation Protection Dosimetry. Vol. 14, No. 4, pp. 311-319, 1985. 2. C. Birattari, A. Ferrari, C.J. Parnell, M. Silari. Radiation Protection Dosimetry. Vol. 19, No.3, pp. 183-186, 1987.
A. Infantino, L. Valtieri, G. Cicoria, D. PancaldI, M. Marengo, D. Mostacci (2012). Measurement of Argon-41 in a PET medical facility. EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING, 39(2 Supplement), S379-S379 [10.1007/s00259-012-2223-8].
Measurement of Argon-41 in a PET medical facility
INFANTINO, ANGELO;MOSTACCI, DOMIZIANO
2012
Abstract
Introduction: In a medical cyclotron facility, Argon-41 (t½ = 109.34m) is produced by the activation of air due to neutron flux during the production of PET radionuclides, according to the 40Ar(n,γ)41Ar reaction. While theoretical estimations of the Argon-41 production have been published, no data were given on experimental measurements. In this work we describe a sampling methodology and report the results of an extensive measurements campaign . Materials and Methods: In order to measure Argon-41 activity, air samples were taken inside the cyclotron bunker and at the stack of the cyclotron bunker in a modified Marinelli-beaker during the routine production of 18F and 11C. The 1000 cm3 Marinelli-beaker was provided with two valves, in order to allow air flow and connection to a pump. Samples analysis was performed in gamma-ray spectrometry system equipped with HPGe detector. The spectrometer was calibrated with a certified water solution and correction factors for sample density were evaluated using the Labsocs software. Routine production of the PET radionuclides were performed with a 16.5 MeV GE-PETtrace cyclotron; the ventilation rate inside the bunker was varied between 0 and about 15 air changes per hour. Results and Conclusions: The saturation yield of 41Ar production in the air of the bunker with no ventilation resulted to be 3.4 ± 0.3 (Bq/l)/μA. The amount of radioactivity released in the environment depends on many parameters, such as the irradiation duration, the integrated current, the ventilation rates etc. The peak activity concentration of Argon-41 in the exhaust during routine 18F production was 1.4 ± 0.5 Bq/l in dual beam irradiations with a beam current of 80 μA, while for 11C production peak activity concentration resulted to be 0.8 ± 0.2 Bq/l in single beam irradiations at 70 μA. These results confirm that the average activity concentration in the air released in external environment by a PET cyclotron centre can be maintained under the limit of radiological relevance. References: 1. C. Birattari, M. Bonardi, A. Ferrari, M. Silari. Radiation Protection Dosimetry. Vol. 14, No. 4, pp. 311-319, 1985. 2. C. Birattari, A. Ferrari, C.J. Parnell, M. Silari. Radiation Protection Dosimetry. Vol. 19, No.3, pp. 183-186, 1987.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
