Evaluation of Using an Octavius 4D Measuring System for Patient-Specific VMAT Quality Assurance

Background: Quality assurance (QA) programs are designed to improve the quality and safety of radiation treatments, including patient-specific QA (PSQA). The objective of this study was to investigate the conditions in which pretreatment PSQA is performed, to evaluate the root cause of the implement...

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Main Authors: Yawo Atsu Constantino Fiagan, Kodjo Joël Fabrice N‘Guessan, Adama Diakité, Komlanvi Victor Adjenou, Thierry Gevaert, Dirk Verellen
Format: Article
Language:English
Published: MDPI AG 2025-02-01
Series:Radiation
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Online Access:https://www.mdpi.com/2673-592X/5/1/9
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author Yawo Atsu Constantino Fiagan
Kodjo Joël Fabrice N‘Guessan
Adama Diakité
Komlanvi Victor Adjenou
Thierry Gevaert
Dirk Verellen
author_facet Yawo Atsu Constantino Fiagan
Kodjo Joël Fabrice N‘Guessan
Adama Diakité
Komlanvi Victor Adjenou
Thierry Gevaert
Dirk Verellen
author_sort Yawo Atsu Constantino Fiagan
collection DOAJ
description Background: Quality assurance (QA) programs are designed to improve the quality and safety of radiation treatments, including patient-specific QA (PSQA). The objective of this study was to investigate the conditions in which pretreatment PSQA is performed, to evaluate the root cause of the implementation of more complex techniques, and to identify areas for potential improvement. Materials/Methods: The Octavius 4D (O4D) system accuracy was evaluated using an O4D homogeneous phantom for different field sizes. Tests of the system response to dose linearity, field sizes, and PDD differences were performed against calculated doses for a 6 MV photon beam. The pretreatment verification of 40 VMAT plans was performed using the PTW VeriSoft software (version 8.0.1) for local and global 3D gamma analysis. The reconstructed 3D dose was compared to the calculated dose using 2%/2 mm and 3%/3 mm, 20% of the low-dose threshold, and 95% of the gamma passing rate (%GP) tolerance level. The sensitivity of the O4D system in detecting VMAT delivery and setup errors has been investigated by measuring the variation in %GP values before and after the simulated errors. Results: The O4D system reported good agreement for linearity, field size, and PDD differences with TPS dose, being within ±2% tolerance. The output factors were consistent between the ionization chamber and the O4D detector down to a 4 × 4 cm<sup>2</sup> field size with a maximum deviation less than 1%. The introduction of deliberate errors caused a decrease in %GP values. In most scenarios, the %GP value of the simulated errors was detected with 2%/2 mm. Conclusion: The results indicate that the O4D system is sensitive enough to detect delivery and setup errors with the restrictive global criterion of 2%/2 mm for routine pretreatment verification.
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spelling doaj-art-9cba8e9f5e814fbd9a0f1d9daf76bb4f2025-08-20T03:44:04ZengMDPI AGRadiation2673-592X2025-02-0151910.3390/radiation5010009Evaluation of Using an Octavius 4D Measuring System for Patient-Specific VMAT Quality AssuranceYawo Atsu Constantino Fiagan0Kodjo Joël Fabrice N‘Guessan1Adama Diakité2Komlanvi Victor Adjenou3Thierry Gevaert4Dirk Verellen5Iridium Netwerk, Radiation Oncology, Oosterveldlaan 22, 2610 Antwerp, BelgiumDepartment of Radiation Oncology, International Cancer Centre of Lomé, Lomé 6176, TogoDepartment of Radiation Oncology, International Cancer Centre of Lomé, Lomé 6176, TogoDepartment of Radiation Oncology, International Cancer Centre of Lomé, Lomé 6176, TogoFaculty of Medicine and Pharmacy, Vrije Universiteit Brussel, 1090 Brussels, BelgiumIridium Netwerk, Radiation Oncology, Oosterveldlaan 22, 2610 Antwerp, BelgiumBackground: Quality assurance (QA) programs are designed to improve the quality and safety of radiation treatments, including patient-specific QA (PSQA). The objective of this study was to investigate the conditions in which pretreatment PSQA is performed, to evaluate the root cause of the implementation of more complex techniques, and to identify areas for potential improvement. Materials/Methods: The Octavius 4D (O4D) system accuracy was evaluated using an O4D homogeneous phantom for different field sizes. Tests of the system response to dose linearity, field sizes, and PDD differences were performed against calculated doses for a 6 MV photon beam. The pretreatment verification of 40 VMAT plans was performed using the PTW VeriSoft software (version 8.0.1) for local and global 3D gamma analysis. The reconstructed 3D dose was compared to the calculated dose using 2%/2 mm and 3%/3 mm, 20% of the low-dose threshold, and 95% of the gamma passing rate (%GP) tolerance level. The sensitivity of the O4D system in detecting VMAT delivery and setup errors has been investigated by measuring the variation in %GP values before and after the simulated errors. Results: The O4D system reported good agreement for linearity, field size, and PDD differences with TPS dose, being within ±2% tolerance. The output factors were consistent between the ionization chamber and the O4D detector down to a 4 × 4 cm<sup>2</sup> field size with a maximum deviation less than 1%. The introduction of deliberate errors caused a decrease in %GP values. In most scenarios, the %GP value of the simulated errors was detected with 2%/2 mm. Conclusion: The results indicate that the O4D system is sensitive enough to detect delivery and setup errors with the restrictive global criterion of 2%/2 mm for routine pretreatment verification.https://www.mdpi.com/2673-592X/5/1/9Octavius 4D systempatient-specific quality assurancegamma passing rate
spellingShingle Yawo Atsu Constantino Fiagan
Kodjo Joël Fabrice N‘Guessan
Adama Diakité
Komlanvi Victor Adjenou
Thierry Gevaert
Dirk Verellen
Evaluation of Using an Octavius 4D Measuring System for Patient-Specific VMAT Quality Assurance
Radiation
Octavius 4D system
patient-specific quality assurance
gamma passing rate
title Evaluation of Using an Octavius 4D Measuring System for Patient-Specific VMAT Quality Assurance
title_full Evaluation of Using an Octavius 4D Measuring System for Patient-Specific VMAT Quality Assurance
title_fullStr Evaluation of Using an Octavius 4D Measuring System for Patient-Specific VMAT Quality Assurance
title_full_unstemmed Evaluation of Using an Octavius 4D Measuring System for Patient-Specific VMAT Quality Assurance
title_short Evaluation of Using an Octavius 4D Measuring System for Patient-Specific VMAT Quality Assurance
title_sort evaluation of using an octavius 4d measuring system for patient specific vmat quality assurance
topic Octavius 4D system
patient-specific quality assurance
gamma passing rate
url https://www.mdpi.com/2673-592X/5/1/9
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