Technical Note: Multicenter study of TrueBeam FFF beams with a new stereotactic diode: Can a common small field signal ratio curve be defined?

Cagni, E.; Russo, S.; Reggiori, G.; Bresciani, S.; Fedele, David A.; Iori, Mauro; Marino, C.; Nardiello, B.; Ruggieri, R.; Strigari, Lidia; Mancosu, P.

doi:10.1118/1.4961744

Cited by 15 publications

(10 citation statements)

References 44 publications

(43 reference statements)

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“…This exploratory phase resulted in better defined guidelines on how to design our subsequent studies. A multicentric [6] study on small-field dosimetry was then performed using the 10 FFF MV beam on 8 True-Beam linacs, with the awareness that EFS measurements were mandatory when comparing OF data over different centers. A strong relationship between OF det and the EFS was obtained and its suitability in evaluating uncorrect OF was assessed indicating the Razor as a good detector for small-beam OF evaluation.…”

Section: Discussionmentioning

confidence: 99%

“…This may lead to a possible increase of those dosimetric uncertainties that represent the major features of small beams in comparison to wide fields [1][2][3]. Sharing of the measured data in terms of output factors (OF) for small fields, with regard to many different combinations of machines and dosimeters [4][5][6][7][8], was promoted with a specific working group focused on SBRT. Other had similar experiences [9,10], all with the aim to quantify systematic inaccuracies of small fields dosimetry.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, in small beams the positioning accuracy of the collimating devices is also important, since e.g. 1 mm error in a 1 × 1 cm 2 field setting can result in a 2-4% error in the measured dose or OF [6].…”

Section: Introductionmentioning

confidence: 99%

“…Alfonso [13] correction factors k Qclin Qmsr fclin fmsr , , were not considered for any of the studied detectors. Details on Linac models involved in the studies have been previously specified [4][5][6].…”

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confidence: 99%

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A multi-center output factor intercomparison to uncover systematic inaccuracies in small field dosimetry

Clemente

Masi²,

Fiandra

et al. 2018

Physics and Imaging in Radiation Oncology

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A B S T R A C TLarge uncertainties in output factor (OF) small fields dosimetry motivated multicentric studies. The focus of the study was the determination of the OFs, for different linacs and radiosurgery units, using new-generation detectors. Intercomparison studies between radiotherapy centers improved quality dosimetry practices. Results confirmed the effectiveness of the studies to uncover large systematic inaccuracies in small field dosimetry.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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A multi-center output factor intercomparison to uncover systematic inaccuracies in small field dosimetry

Clemente

Masi²,

Fiandra

et al. 2018

Physics and Imaging in Radiation Oncology

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“…In detail, 15 full papers. [19][20][21][22][23][28][29][30][31][32][34][35][36]38,40 5 reviews, 18,27,33,37,41 1 editorial, 25 and 3 letters to the editor 24,26,39 were published. A total of more than 100 medical physicists were authors of at least one article, showing high level of members' engagement.…”

Section: B Engagement Metricsmentioning

confidence: 99%

Lean Thinking to manage a national working group on physics aspects of Stereotactic Body Radiation Therapy

Mancosu

Russo

Antonucci³

et al. 2021

Medical Physics

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To report how the adoption of a Lean Thinking mindset in the management of a national working group (WG) on the physics of stereotactic body radiation therapy (SBRT) contributed to achieve SBRT standardization objectives. Methods: Vision for the WG has been established as fragmentation reduction and process harmonization enhancement in SBRT for Italian centers. Two main research themes of the technical aspects of SBRT emerged as areas with major standardization improvement needs, small field dosimetry and SBRT planning comparisons, to be investigated through multi-institutional studies. The management of the WG leveraged on the Lean concept of fostering self-organization in a non-hierarchical environment. Four progressive involvement levels were defined for each study. No specific "scientific" preexperience was required to propose and coordinate a project, just requiring a voluntary commitment. People engagement was measured in terms of number of published articles. The standardization goals have been conducted through a simplified "5S" (Sort, Set in Order, Shine, Standardize, and Sustain) methodology, first considering a phase of awareness (the first three "S"), then identifying and implementing standardization actions (the last two "S"). Results: Since the beginning, 157 medical physicists joined the AIFM/SBRT-WG. Twenty-four papers/reviews/letters have been published in the period 2014-2019 on major radiation oncology journals, authored by >100 physicists (>50% working in small hospitals). Six over 12 first authors worked in peripheral/small hospitals, with no prior publication as first author. These studies contributed to the awareness and standardization phases for both small-field dosimetry and planning. In particular, errors in small-field measurements in 8% of centers were detected thanks to a generalized output factor curve in function of the effective field size created by averaging data available from different Linacs. Furthermore, planner's experience in SBRT was correlated with dosimetric parameters in the awareness phase; while sharing median dose volume histograms (DVHs) reduced variability among centers while keeping the same level of plan complexity. Finally, all the dosimetric parameters statistically significant to the planner experience during the awareness phase, were no longer significantly different in the standardization phase. Conclusions: The experience of our SBRT-WG has shown how a Lean Thinking mindset could foster the SBRT procedure standardization and spread the physics of SBRT knowledge, enhancing personal growth. Our expectation is to inspire other scientific societies that have to deal with fragmented contexts or pursue processes harmonization through Lean principles.

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Feasibility study of using Stereotactic Field Diode for field output factors measurement and evaluating three new detectors for small field relative dosimetry of 6 and 10 MV photon beams

Gul

Fukuda

Mizuno

et al. 2020

J Applied Clin Med Phys

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This study assesses the feasibility of using stereotactic field diode (SFD) as an alternate to gaf chromic films for field output factor (FF) measurement and further evaluating three new detectors for small field dosimetry. Varian 21EX linear accelerator was used to generate 6 and 10 MV beams of nominal square fields ranging from 0.5 × 0.5 cm2 to 10 × 10 cm2. One passive (EBT3 films) and five active detectors including IBA RAZOR diode(RD), SFD, RAZOR nanochamber (RNC), pinpoint chamber (PTW31023), and semiflex chamber (PTW31010) were employed. FFs were measured using films and SFD while beam profiles and percentage depth dose (PDD) distribution were acquired with active detectors. Polarity (kpol) and recombination (ks) effects of ion chambers were determined and corrected for output ratio measurement. Correction factors (CF) of RD, RNC, and PTW31023 in axial and radial orientation were also measured. Stereotactic field diode measured FFs have shown good agreement with films (with difference of <1%). RD and RNC measured beam profiles were within 3% deviation from the SFD values. Variation in kpol with field size for RNC and PTW31023 was up to 4% and 0.4% (for fields ≥ 1 × 1 cm2), respectively, while variation in ks of PTW31023 was <0.2 %. The maximum values of CF have been calculated to be 5.2%, 2.0%, 13.6%, and 25.5% for RD, RNC, PTW31023‐axial, and PTW31023‐radial respectively. This study concludes that SFD with appropriate CFs as given in TRS 483 may be used for measuring FFs as an alternate to EBT3 films. Whereas RD and RNC may be used for beam profile and PDD measurement in small fields. Considering the limit of usability of 2%, RNC may be used without CF for FF measurement in the smallfields investigated in this study.

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Technical Note: Multicenter study of TrueBeam FFF beams with a new stereotactic diode: Can a common small field signal ratio curve be defined?

Abstract: EFS measurements were confirmed to be mandatory when comparing SRs over different centers. An equation establishing a functional relation between SRs and the EFS was obtained and tested for the new Razor diode.

Cited by 15 publications

References 44 publications

A multi-center output factor intercomparison to uncover systematic inaccuracies in small field dosimetry

A multi-center output factor intercomparison to uncover systematic inaccuracies in small field dosimetry

Lean Thinking to manage a national working group on physics aspects of Stereotactic Body Radiation Therapy

Feasibility study of using Stereotactic Field Diode for field output factors measurement and evaluating three new detectors for small field relative dosimetry of 6 and 10 MV photon beams

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