Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/34802
Title: Repeatability and Reproducibility of Microdosimetry With a Mini-TEPC
Authors: BIANCHI, Anna 
Selva, A
Colautti, P
Petringa, G
Cirrone, P
RENIERS, Brigitte 
Parisi, A
Vanhavere, F
Conte, V
Issue Date: 2021
Publisher: 
Source: Frontiers of Physics, 9 (Art N° 727816)
Abstract: Experimental microdosimetry measures the energy deposited in a microscopic sensitive volume (SV) by single ionizing particles traversing the SV or passing by. The fundamental advantage of experimental microdosimetry over the computational approach is that the first allows to determine distributions of energy deposition when information on the energy and nature of the charged particles at the point of interest is incomplete or fragmentary. This is almost always the case in radiation protection applications, but discrepancies between the modelled and the actual scenarios should be considered also in radiation therapy. Models for physical reality are always imperfect and rely both on basic input data and on assumptions and simplifications that are necessarily implemented. Furthermore, unintended events due to human errors or machine/system failures can be minimized but cannot be completely avoided. Though in proton radiation therapy (PRT) a constant relative biological effectiveness (RBE) of 1.1 is assumed, there is evidence of an increasing RBE towards the end of the proton penetration depth. Treatment Planning Systems (TPS) that take into account a variable linear energy transfer (LET) or RBE are already available and could be implemented in PRT in the near future. However, while the calculated dose distributions produced by the TPS are routinely verified with ionization chambers as part of the quality assurance program of every radiotherapy center, there is no commercial detector currently available to perform routine verification of the radiation quality, calculated by the TPS through LET or RBE distributions. Verification of calculated LET is required to make sure that a complex robustly optimized plan will be delivered as planned. The scientific community is coming to conclusion that a new domain of Quality Assurance additionally to the physical dose verification is required, and microdosimetry can be the right approach to address that. A first important prerequisite is the repeatability and reproducibility of microdosimetric measurements. This work aims at studying experimentally the repeatability and reproducibility of microdosimetric measurements performed with a miniaturized Tissue Equivalent Proportional Counter (mini-TEPC) in a 62 MeV proton beam. Experiments were carried out within 1 year and without propane gas recharging and by different operators. RBE was also calculated by applying the Loncol's weighting function r(y) to microdosimetric distributions. Demonstration of reproducibility of measured microdosimetric quantities y F , y D and RBE 10 in 62 MeV proton beam makes this TEPC
Keywords: microdosimetry;microdosimeters;proton theraphy;RBE = relative biological effectiveness;hadron therapy;reproducibility;repeatibility;radiation quality assessment
Document URI: http://hdl.handle.net/1942/34802
ISSN: 2095-0462
e-ISSN: 2095-0470
DOI: 10.3389/fphy.2021.727816
ISI #: 000698466900001
Rights: Copyright © 2021 Bianchi, Selva, Colautti, Petringa, Cirrone, Reniers, Parisi, Vanhavere and Conte. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Category: A1
Type: Journal Contribution
Appears in Collections:Research publications

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