A new calculation method for the free electron fraction of an ionization chamber in the ultra-high-dose-per-pulse regimen.

Electrons Radiometry / methods Particle Accelerators
Free electron fraction K(sat) Parallel plate ionization chamber Ultra-high-dose-per-pulse

Journal

Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB)
ISSN: 1724-191X
Titre abrégé: Phys Med
Pays: Italy
ID NLM: 9302888

Informations de publication

Date de publication:
Nov 2022
Historique:
received: 02 05 2022
revised: 27 10 2022
accepted: 01 11 2022
pubmed: 13 11 2022
medline: 30 11 2022
entrez: 12 11 2022
Statut: ppublish

Résumé

The free electron fraction is the fraction of electrons, produced inside the cavity of an ionization chamber after irradiation, which does not bind to gas molecules and thereby reaches the electrode as free electrons. It is a fundamental quantity to describe the recombination processes of an ionization chamber, as it generates a gap of positive charges compared to negative ones, which certainly will not undergo recombination. The free electron fraction depends on the specific chamber geometry, the polarizing applied voltage and the gas thermodynamic properties. Therefore, it is necessary to evaluate such fraction in an accurate and easy way for any measurement condition. In this paper, a simple and direct method for evaluating the free electron fraction of ionization chambers is proposed. We first model the capture process of the electrons produced inside an ionization chamber after the beam pulse; then we present a method to evaluate the free electron fraction based on simple measurements of collected charge, by varying the applied voltage. Finally, the results obtained using an Advanced Markus chamber irradiated with a Flash Radiotherapy dedicated research Linac (ElectronFlash) to estimate the free electron fraction are presented. The proposed method allows the use of a conventional ionization chamber for measurements in ultra-high-dose-per-pulse (UHDP) conditions, up to values of dose-per-pulse at which the perturbation of the electric field due to the generated charge can be considered negligible.

Identifiants

DOI: 10.1016/j.ejmp.2022.11.001 PMID: 36370686
pubmed: 36370686
pii: S1120-1797(22)02091-9
doi: 10.1016/j.ejmp.2022.11.001
pii:
doi:

Types de publication

Journal Article

Langues

eng

Sous-ensembles de citation

IM

Pagination

175-180

Informations de copyright

Copyright © 2022 Associazione Italiana di Fisica Medica e Sanitaria. Published by Elsevier Ltd. All rights reserved.

Déclaration de conflit d'intérêts

Declaration of Competing Interest F. Galante, G. Mariani, M. Pacitti and G. Felici are SIT employees; G. Felici is a SIT shareholder; A. Gasparini received a grant for a post doc position funded by SIT S.p.A. The remaining authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Auteurs

Fabio Di Martino (F)

Fisica Sanitaria, Azienda Ospedaliero Universitaria Pisa AOUP, ed.18 via Roma 67, Pisa, Italy; Centro Pisano ricerca e implementazione clinica Flash Radiotherapy (CPFR@CISUP), Presidio S. Chiara, ed. 18 via Roma 67, Pisa, Italy; INFN, Sezione di Pisa, Largo B. Pontecorvo 3, I-57127 Pisa, Italy. Electronic address: f.dimartino@ao-pisa.toscana.it.

Damiano Del Sarto (D)

Centro Pisano ricerca e implementazione clinica Flash Radiotherapy (CPFR@CISUP), Presidio S. Chiara, ed. 18 via Roma 67, Pisa, Italy.

Salvatore Barone (S)

SIT S.p.A., Aprilia 04011, Latina, Italy.

Maria Giuseppina Bisogni (M)

Centro Pisano ricerca e implementazione clinica Flash Radiotherapy (CPFR@CISUP), Presidio S. Chiara, ed. 18 via Roma 67, Pisa, Italy; Department of Physics, University of Pisa, Largo B. Pontecorvo 3, I-57127 Pisa, Italy; INFN, Sezione di Pisa, Largo B. Pontecorvo 3, I-57127 Pisa, Italy.

Simone Capaccioli (S)

Centro Pisano ricerca e implementazione clinica Flash Radiotherapy (CPFR@CISUP), Presidio S. Chiara, ed. 18 via Roma 67, Pisa, Italy; Department of Physics, University of Pisa, Largo B. Pontecorvo 3, I-57127 Pisa, Italy.

Federica Galante (F)

SIT S.p.A., Aprilia 04011, Latina, Italy.

Alessia Gasparini (A)

Iridium Kankernetwerk, 2610 Antwerp, Belgium; Antwerp University, Faculty of Medicine and Health Sciences, 2610 Antwerp, Belgium.

Giulia Mariani (G)

SIT S.p.A., Aprilia 04011, Latina, Italy.

Luigi Masturzo (L)

Department of Physics, University of Pisa, Largo B. Pontecorvo 3, I-57127 Pisa, Italy; INFN, Sezione di Pisa, Largo B. Pontecorvo 3, I-57127 Pisa, Italy.

Marco Montefiori (M)

Department of Physics, University of Pisa, Largo B. Pontecorvo 3, I-57127 Pisa, Italy; INFN, Sezione di Pisa, Largo B. Pontecorvo 3, I-57127 Pisa, Italy.

Matteo Pacitti (M)

SIT S.p.A., Aprilia 04011, Latina, Italy.

Fabiola Paiar (F)

Centro Pisano ricerca e implementazione clinica Flash Radiotherapy (CPFR@CISUP), Presidio S. Chiara, ed. 18 via Roma 67, Pisa, Italy; INFN, Sezione di Pisa, Largo B. Pontecorvo 3, I-57127 Pisa, Italy; Radiation Oncology Unit, Department of Translational Research, University of Pisa, Pisa, Italy.

Jake Harold Pensavalle (J)

Department of Physics, University of Pisa, Largo B. Pontecorvo 3, I-57127 Pisa, Italy; INFN, Sezione di Pisa, Largo B. Pontecorvo 3, I-57127 Pisa, Italy.

Francesco Romano (F)

INFN, Sezione di Catania, Catania, Italy.

Stefano Ursino (S)

Centro Pisano ricerca e implementazione clinica Flash Radiotherapy (CPFR@CISUP), Presidio S. Chiara, ed. 18 via Roma 67, Pisa, Italy; INFN, Sezione di Pisa, Largo B. Pontecorvo 3, I-57127 Pisa, Italy; Radiation Oncology Unit, Department of Translational Research, University of Pisa, Pisa, Italy.

Verdi Vanreusel (V)

Iridium Kankernetwerk, 2610 Antwerp, Belgium; Antwerp University, Faculty of Medicine and Health Sciences, 2610 Antwerp, Belgium.

Dirk Verellen (D)

Iridium Kankernetwerk, 2610 Antwerp, Belgium; Antwerp University, Faculty of Medicine and Health Sciences, 2610 Antwerp, Belgium.

Giuseppe Felici (G)

SIT S.p.A., Aprilia 04011, Latina, Italy.

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Classifications MeSH

questionsmedicales.fr › Phénomènes physiques › Phénomènes magnétiques › Phénomènes électromagnétiques › Électrons › A new calculation method for the free electron...
questionsmedicales.fr › Techniques d'investigation › Radiométrie › A new calculation method for the free electron...
questionsmedicales.fr › Équipement et fournitures › Équipement et fournitures pour les applications des radiations › Accélérateurs de particules › A new calculation method for the free electron...