IPEM topical report 1: guidance on implementing flattening filter free (FFF) radiotherapy

Budgell, Geoff J; Brown, K L; Cashmore, J.; Duane, S; Frame, J.W.; Hardy, Mark; Paynter, David; Thomas, Russell

doi:10.1088/0031-9155/61/23/8360

Cited by 49 publications

(68 citation statements)

References 79 publications

(106 reference statements)

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“…the effect of the scanning phantom would be expected to be negligible. As CC13 was used to collect the source data for the RBD, including small field and FFF beam data, we have to measure data by using it comparing with the RBD. Data measurement with other suitable devices, such as a smaller cavity chamber, diode, and diamond detector, might be needed for accurate commissioning of small field and FFF beam data; however, the RBD do not include these data.…”

Section: Discussionmentioning

confidence: 99%

Do the representative beam data for TrueBeam^™ linear accelerators represent average data?

Tanaka

Mizuno

Akino

et al. 2019

J Applied Clin Med Phys

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If the vendor's representative beam data (RBD) for TrueBeam linear accelerators are to be valid for use in clinical practice, the variations in the beam data used for beam modeling must be small. Although a few studies have reported the variation of the beam data of the TrueBeam machines, the numbers of machines analyzed in those studies were small. In this study, we investigated the variation in the beam data for 21 TrueBeam machines collected from 17 institutions with their agreement. In the exponential regions, the percent depth dose (PDD) values showed very small variation, <1% for all the photon energies analyzed. Similarly, the off‐center ratio (OCR) values also showed small variation for all energies. In the field regions, the standard deviations of the values of dose difference (DD) between the data for each machine and the study average were <1% for field sizes ≥100 × 100 mm2. The maximum distance‐to‐agreement from the average data was <0.5 mm in the penumbra regions. The output factor (OPF) values also showed very small variation (<1%) for all energies and field sizes. Both the PDD and OCR of the average study data showed good agreement with the vendor's RBD for field sizes ≥100 × 100 mm2. The OPF of the average study data also showed good agreement with the vendor's RBD for all field sizes. However, although all the institutions used ionization chambers with similar cavity volumes, the 30 × 30 mm2 field size showed large DD variations (≥2%) in OCR in the field regions. We conclude that the intermachine variability of TrueBeam linear accelerators was very small except for small field dosimetry, supporting the validity of the use of the RBD for clinical applications. The use of the vendor's RBD might greatly facilitate the quick installation of a new linear accelerator.

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Section: Discussionmentioning

confidence: 99%

Do the representative beam data for TrueBeam^™ linear accelerators represent average data?

Tanaka

Mizuno

Akino

et al. 2019

J Applied Clin Med Phys

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“…This gradient means that setup errors in both IC Profiler and EPID will have an exaggerated influence. Varian FFF beams utilize the same electron beam (including beam steering settings) as the equivalent energy flattened beam 16. Treatment centers whose beams are configured in this way could simply beam angle steer the flattened beam and then set the same steering settings for the corresponding FFF beam.…”

Section: Discussionmentioning

confidence: 99%

A proposed method for linear accelerator photon beam steering using EPID

Barnes

Menk

Lamichhane

et al. 2018

J Applied Clin Med Phys

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Beam steering is the process of calibrating the angle and translational position with which a linear accelerator's (linac's) electron beam strikes the x‐ray target with respect to the collimator rotation axis. The shape of the dose profile is highly dependent on accurate beam steering and is essential for ensuring correct delivery of the radiotherapy treatment plan. Traditional methods of beam steering utilize a scanning water tank phantom that makes the process user‐dependent. This study is the first to provide a methodology for both beam angle steering and beam translational position steering based on EPID imaging of the beam and does not require a phantom. Both the EPID‐based beam angle steering and beam translational steering methods described have been validated against IC Profiler measurement. Wide field symmetry agreement was found between the EPID and IC Profiler to within 0.06 ± 0.14% (1 SD) and 0.32 ± 0.11% (1 SD) for flattened and flattening‐filter‐free (FFF) beams, respectively. For a 1.1% change in symmetry measured by IC Profiler the EPID method agreed to within 0.23%. For beam translational position steering, the EPID method agreed with IC Profiler method to within 0.03 ± 0.05 mm (1 SD) at isocenter. The EPID‐based methods presented are quick to perform, simple, accurate and could easily be integrated with the linac, potentially via the MPC application. The methods have the potential to remove user variability and to standardize the process of beam steering throughout the radiotherapy community.

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“…[6][7][8] The use of flattening free (FFF) beams in VMAT SABR has proven to be advantageous in terms of shorter treatment times, conformity, and critical organ sparing. [9][10][11][12][13][14][15] Alternatively, dynamic conformal arc techniques are considered better to avoid interplay effects due to dose-rate modulation and multileaf collimator (MLC) movement encountered during VMAT delivery. However, extending the arc length (using two partial arcs) in VMAT is suggested to be safe with regard to interplay effects.…”

Section: Introductionmentioning

confidence: 99%

Improvement of off‐axis SABR plan verification results by using adapted dose reconstruction algorithms for the Octavius 4D system

et al. 2018

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The errors in QA phantom measurements due to dose reconstruction at off-axis target geometry have been demonstrated for conformal arcs and clinical VMAT SABR plans. A novel software solution implemented by the vendor to allow accurate pass rates has been tested. This solution enables high-resolution arrays with small active detection areas to be used for quality assurance of SABR treatment plans in the off-axis treatment position.

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IPEM topical report 1: guidance on implementing flattening filter free (FFF) radiotherapy

Cited by 49 publications

References 79 publications

Do the representative beam data for TrueBeam^™ linear accelerators represent average data?

Do the representative beam data for TrueBeam^™ linear accelerators represent average data?

A proposed method for linear accelerator photon beam steering using EPID

Improvement of off‐axis SABR plan verification results by using adapted dose reconstruction algorithms for the Octavius 4D system

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IPEM topical report 1: guidance on implementing flattening filter free (FFF) radiotherapy

Cited by 49 publications

References 79 publications

Do the representative beam data for TrueBeam™ linear accelerators represent average data?

Do the representative beam data for TrueBeam™ linear accelerators represent average data?

A proposed method for linear accelerator photon beam steering using EPID

Improvement of off‐axis SABR plan verification results by using adapted dose reconstruction algorithms for the Octavius 4D system

Contact Info

Product

Resources

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Do the representative beam data for TrueBeam^™ linear accelerators represent average data?

Do the representative beam data for TrueBeam^™ linear accelerators represent average data?