On the determination of reference levels for quality assurance of flattening filter free photon beams in radiation therapy

Clivio, Alessandro; Belosi, M.F.; Cozzi, Luca; Nicolini, G.; Vanetti, Eugenio; Bolard, G.; Fénoglietto, P.; Krauss, H.; Fogliata, Antonella

doi:10.1118/1.4861817

Cited by 8 publications

(6 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In similar measurement, Arnfield et al (48) reported a value of 1.34 ± 0.03% for the same MLC model. Profile symmetry was better than 103% for the commissioned field size ranges and the flatness values of 1.03-1.22 were comparable with values reported for a 6 MV FFF beam in literature (50). Penumbra values could be measured with films, offering high spatial resolution, only for a subset of fields required by IEC standard.…”

Section: Discussionsupporting

confidence: 80%

Dosimetric Optimization and Commissioning of a High Field Inline MRI-Linac

et al. 2020

View full text Add to dashboard Cite

Unique characteristics of MRI-linac systems and mutual interactions between their components pose specific challenges for their commissioning and quality assurance. The Australian MRI-linac is a prototype system which explores the inline orientation, with radiation beam parallel to the main magnetic field. The aim of this work was to commission the radiation-related aspects of this system for its application in clinical treatments. Methods: Physical alignment of the radiation beam to the magnetic field was fine-tuned and magnetic shielding of the radiation head was designed to achieve optimal beam characteristics. These steps were guided by investigative measurements of the beam properties. Subsequently, machine performance was benchmarked against the requirements of the IEC60976/77 standards. Finally, the geometric and dosimetric data was acquired, following the AAPM Task Group 106 recommendations, to characterize the beam for modeling in the treatment planning system and with Monte Carlo simulations. The magnetic field effects on the dose deposition and on the detector response have been taken into account and issues specific to the inline design have been highlighted. Results: Alignment of the radiation beam axis and the imaging isocentre within 2 mm tolerance was obtained. The system was commissioned at two source-to-isocentre distances (SIDs): 2.4 and 1.8 m. Reproducibility and proportionality of the dose monitoring system met IEC criteria at the larger SID but slightly exceeded it at the shorter SID. Profile symmetry remained under 103% for the fields up to ∼34 × 34 and 21 × 21 cm 2 at the larger and shorter SID, respectively. No penumbra asymmetry, characteristic for transverse systems, was observed. The electron focusing effect, which results in high entrance doses on central axis, was quantified and methods to minimize it have been investigated. Conclusion: Methods were developed and employed to investigate and quantify the dosimetric properties of an inline MRI-Linac system. The Australian MRI-linac system has been fine-tuned in terms of beam properties and commissioned, constituting a key step toward the application of inline MRI-linacs for patient treatments.

show abstract

Section: Discussionsupporting

confidence: 80%

Dosimetric Optimization and Commissioning of a High Field Inline MRI-Linac

et al. 2020

View full text Add to dashboard Cite

show abstract

“…based on the measurement at three different Varian LINACs and used the definition proposed by Fogliata et al . [ 9 , 16 ] while reference values proposed in the current study are based on the measurement at 13 Varian LINACs and used the definition suggested by Sahani et al . [ 10 ] Therefore, reference values determined in this work and reference values reported earlier cannot be compared owing to the difference in definitions except for the field size.…”

Section: Discussionmentioning

confidence: 99%

A simplified approach for determination of inflection points of flattening filter-free photon beam using in-house developed software and derivation of reference levels

Sharma,

Dixit,

Sharma

et al. 2023

J Med Phys

View full text Add to dashboard Cite

Aim: This article aimed to present the salient features of the in-house developed Java program for the determination of inflection point and dosimetric parameters of flattening filter-free (FFF) photon beam. Reference levels for the dosimetric parameters of the FFF photon beams were also presented. Materials and Methods: Beam profiles of 6 MV FFF and 10 MV FFF photon beams for a collimator setting of 20 cm × 20 cm measured at 10 cm depth in an isocentric setup acquired from various institutions were analyzed using an in-house developed Java program and manual method. The values of reference dose value (RDV), field size, penumbra, and degree of un-flatness (defined as the lateral separation between 90% [X 90% ], 75% [X 75% ], and 60% [X 60% ] dose points on the profile) were calculated and compared. The reference values of field size, penumbra, and degree of un-flatness were also determined for Varian and Elekta medical electron linear accelerators (LINACs). Results: The maximum differences for RDV determined using the Java method and manual method are 2.4% and 2.7% for 6 and 10 MV FFF photon beams, respectively. The maximum difference between the values of field size, penumbra, and degree of un-flatness determined using Java and manual methods is within 1.3 mm. The reference values of field size and penumbra for Varian LINACs are 19.94 ± 0.10 cm and 0.83 ± 0.08 cm (6 MV FFF) and 19.95 ± 0.10 cm and 0.83 ± 0.08 cm (10 MV FFF). Similarly, the reference values of field size and penumbra for Elekta LINACs are 20.02 ± 0.09 cm and 0.94 ± 0.12 cm (6 MV FFF) and 20.03 ± 0.11 cm and 0.97 ± 0.16 cm (10 MV FFF). Conclusions: A software program was developed in Java for analyzing the beam profiles of FFF photon beams. The results of Java-derived values of dosimetric parameters of FFF photon beams were found in good agreement with the values determined using the manual method. The reference values of these parameters were also derived and quoted using a large cohort of the data.

show abstract

“…In addition to these procedures, the use of the unflatness, slope and peak position has been proposed by Fogliata et al. [ 37 , 38 ]. In our survey, one institution responded that they used such procedures for FFF beam QA.…”

Section: Discussionmentioning

confidence: 99%

Survey on utilization of flattening filter-free photon beams in Japan

Kodama

Yasui

Nishioka³

et al. 2021

Journal of Radiation Research

View full text Add to dashboard Cite

To understand the current state of flattening filter-free (FFF) beam implementation in C-arm linear accelerators (LINAC) in Japan, the quality assurance (QA)/quality control (QC) 2018–2019 Committee of the Japan Society of Medical Physics (JSMP) conducted a 37-question survey, designed to investigate facility information and specifications regarding FFF beam adoption and usage. The survey comprised six sections: facility information, devices, clinical usage, standard calibration protocols, modeling for treatment planning (TPS) systems and commissioning and QA/QC. A web-based questionnaire was developed. Responses were collected between 18 June and 18 September 2019. Of the 846 institutions implementing external radiotherapy, 323 replied. Of these institutions, 92 had adopted FFF beams and 66 had treated patients using them. FFF beams were used in stereotactic radiation therapy (SRT) for almost all disease sites, especially for the lungs using 6 MV and liver using 10 MV in 51 and 32 institutions, respectively. The number of institutions using FFF beams for treatment increased yearly, from eight before 2015 to 60 in 2018. Farmer-type ionization chambers were used as the standard calibration protocol in 66 (72%) institutions. In 73 (80%) institutions, the beam-quality conversion factor for FFF beams was calculated from TPR20,10, via the same protocol used for beams with flattening filter (WFF). Commissioning, periodic QA and patient-specific QA for FFF beams also followed the procedures used for WFF beams. FFF beams were primarily used in high-volume centers for SRT. In most institutions, measurement and QA was conducted via the procedures used for WFF beams.

show abstract

On the determination of reference levels for quality assurance of flattening filter free photon beams in radiation therapy

Cited by 8 publications

References 22 publications

Dosimetric Optimization and Commissioning of a High Field Inline MRI-Linac

Dosimetric Optimization and Commissioning of a High Field Inline MRI-Linac

A simplified approach for determination of inflection points of flattening filter-free photon beam using in-house developed software and derivation of reference levels

Survey on utilization of flattening filter-free photon beams in Japan

Contact Info

Product

Resources

About