Commissioning, dosimetric characterization and machine performance assessment of the LIAC HWL mobile accelerator for Intraoperative Radiotherapy.
Commissioning
Dosimetry
Intra operative electron radiotherapy
Journal
Zeitschrift fur medizinische Physik
ISSN: 1876-4436
Titre abrégé: Z Med Phys
Pays: Germany
ID NLM: 100886455
Informations de publication
Date de publication:
Nov 2020
Nov 2020
Historique:
received:
02
03
2020
revised:
15
05
2020
accepted:
03
06
2020
pubmed:
20
7
2020
medline:
21
9
2021
entrez:
20
7
2020
Statut:
ppublish
Résumé
The LIAC HWL (Sordina IORT Technologies, Vicenza, Italy) is a recently designed mobile linear accelerator for intraoperative electron radiotherapy (IOeRT), producing high dose rate electron beams at four different energy levels. It features a software tool for the visualization of 2D dose distributions, which is based on Monte Carlo simulations. The aims of this work were to (i) assess the dosimetric characteristics of the accelerator, (ii) experimentally verify calculated data exported from the software and (iii) report on commissioning as well as performance of the system during the first year of operation. The electron energies of the LIAC HWL used in this study are 6, 8, 10 and 12 MeV. Diameters of the cylindrically shaped applicators range from 3 to 10cm. We studied two applicator sets with different length ratios of proximal and terminal applicator sections. Reference dosimetry, linearity as well as short- and long-term stability were measured with a PTW Advanced Markus chamber, relative depth dose and profiles were measured using an unshielded diode. Percentage-depth-dose (PDD) and transversal dose profile (TDP) data were exported from the simulation software LIACSim and compared with our measurements. The device reaches dose rates up to 40Gy/min (for 12 MeV). Surface doses for the 10cm applicators are higher than 90%, X-ray background is below 0.6% for all energies. Simulations and measurements of PDD agreed well, with a maximum difference in the depth of the 50% isodose of 0.7mm for the flat-ended applicators and 1mm for the beveled applicators. The simulations slightly underestimate the dose in the lateral parts of the field (difference < 1.8% for flat-ended applicators). The two different applicator sets were dosimetrically equivalent. Long-term stability measurements for the first year of operation ranged from -2.1% to 1.6% (mean: -0.1%). The system is dosimetrically well suited for IOeRT and performed stably and reliably. The software tool for visualization of dose distributions can be used to support treatment planning, following thorough validation.
Sections du résumé
BACKGROUND
BACKGROUND
The LIAC HWL (Sordina IORT Technologies, Vicenza, Italy) is a recently designed mobile linear accelerator for intraoperative electron radiotherapy (IOeRT), producing high dose rate electron beams at four different energy levels. It features a software tool for the visualization of 2D dose distributions, which is based on Monte Carlo simulations. The aims of this work were to (i) assess the dosimetric characteristics of the accelerator, (ii) experimentally verify calculated data exported from the software and (iii) report on commissioning as well as performance of the system during the first year of operation.
METHODS
METHODS
The electron energies of the LIAC HWL used in this study are 6, 8, 10 and 12 MeV. Diameters of the cylindrically shaped applicators range from 3 to 10cm. We studied two applicator sets with different length ratios of proximal and terminal applicator sections. Reference dosimetry, linearity as well as short- and long-term stability were measured with a PTW Advanced Markus chamber, relative depth dose and profiles were measured using an unshielded diode. Percentage-depth-dose (PDD) and transversal dose profile (TDP) data were exported from the simulation software LIACSim and compared with our measurements.
RESULTS
RESULTS
The device reaches dose rates up to 40Gy/min (for 12 MeV). Surface doses for the 10cm applicators are higher than 90%, X-ray background is below 0.6% for all energies. Simulations and measurements of PDD agreed well, with a maximum difference in the depth of the 50% isodose of 0.7mm for the flat-ended applicators and 1mm for the beveled applicators. The simulations slightly underestimate the dose in the lateral parts of the field (difference < 1.8% for flat-ended applicators). The two different applicator sets were dosimetrically equivalent. Long-term stability measurements for the first year of operation ranged from -2.1% to 1.6% (mean: -0.1%).
CONCLUSIONS
CONCLUSIONS
The system is dosimetrically well suited for IOeRT and performed stably and reliably. The software tool for visualization of dose distributions can be used to support treatment planning, following thorough validation.
Identifiants
pubmed: 32682654
pii: S0939-3889(20)30063-5
doi: 10.1016/j.zemedi.2020.06.004
pii:
doi:
Types de publication
Journal Article
Langues
eng
Sous-ensembles de citation
IM
Pagination
279-288Informations de copyright
Copyright © 2020. Published by Elsevier GmbH.