Credentialing of radiotherapy centres in Australasia for TROG 09.02 (Chisel), a Phase III clinical trial on stereotactic ablative body radiotherapy of early stage lung cancer

Kron, Tomas; Chesson, Brent; Hardcastle, Nicholas; Crain, Melissa; Clements, Natalie; Burns, Mark W.; Ball, David

doi:10.1259/bjr.20170737

Cited by 20 publications

(15 citation statements)

References 36 publications

(36 reference statements)

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“…41,42,46 Measurements in lung phantoms, particularly of small fields, are becoming increasingly important as more departments attempt to commission or validate treatment planning system calculations for stereotactic ablative radiotherapy treatments of small lung lesions. 21,26,27 Film measurements in lung phantoms should be corrected using values in Tables I--III, as shown in Eq. (1).…”

Section: Discussionmentioning

confidence: 99%

“…22 Lung tumor sizes being treated can be as small as 3 mm in diameter, 23 and advancing imaging techniques and motion management strategies are allowing margins to be reduced, sparing more healthy lung tissue. 24,25 It is therefore clear that accurate experimental dose verification of very small fields in lung phantoms is imperative (see, e.g., 26,27 ).…”

Section: Introductionmentioning

confidence: 99%

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Technical Note: Small field dose correction factors for radiochromic film in lung phantoms

Charles¹,

Crowe

Kairn

2021

Medical Physics

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Purpose: Radiochromic film has been established as a detector that can be used without the need for perturbation correction factors for small field dosimetry in water. However, perturbation factors in low density media such as lung have yet to be published. This study calculated the factors required to account for the perturbation of radiochromic film when used for small field dosimetry in lung equivalent material. Method: Monte Carlo simulations were used to calculate dose to Gafchromic EBT3 film when placed inside a lung phantom. The beam simulated had a nominal energy of 6 MV and the field sizes simulated ranged from 10 × 10 mm 2 to 30 × 30 mm 2 . The lung density simulated was varied between 0.2 and 0.3 g/cm 3 . Each simulation was repeated with the film replaced by lung material (the same as the surrounding medium), and the required correction factors for film dosimetry in lung ( D Med,Q D Det,Q ) were calculated by dividing the dose in lung by the dose in film. Results: For field sizes 30 × 30 mm 2 and larger, no correction factors were required. At a 20 × 20 mm 2 field size, small corrections were required, but were within the approximate accuracy of film dosimetry (~2%). For a 10 × 10 mm 2 field size, significant correction factors need to be applied (0.935 for lung density of 0.20 g/cm 3 to 0.963 for lung density of 0.30 g/cm 3 ). The values lower than one mean that the film is over-responding. At the "upstream" lung-water interface the correction factors were close to unity; while at the downstream interface the corrections required were marginally smaller to those at the center of lung. One centimeter or more away from the interfaces, the correction factor did not vary as a function distance from the interface (in the beam direction). Away from the central axis (perpendicular to the beam direction), the correction factors increased slightly (away from unity) as a function of off-axis distance, before abruptly changing direction at the penumbra, with the film actually under-responding by~10% outside the field edges. Conclusion: Accurate dosimetry of very small fields (15 × 15 mm 2 or smaller) using radiochromic film requires correction factors for the perturbation of the film on the surrounding lung material. This correction factor was as high as 6.5% for a 10 × 10 mm 2 field size and a density of 0.2 g/cm 3 . This will increase if either the density or the field size decrease further. This correction factor does not vary as a function of depth in lung once charged particle equilibrium is established.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Technical Note: Small field dose correction factors for radiochromic film in lung phantoms

Charles¹,

Crowe

Kairn

2021

Medical Physics

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“…Review guidelines for 4DCT image sets were developed based on commissioning work 16 and experiences from quality assurance for several clinical trials. 17,18 An in-house training programme was developed for medical physicists to establish a minimum skillset for performing 4DCT reviews in the context of SABR. A patient-specific review checklist was designed to aid in the review process and facilitate data collection, which has been provided as supplementary material.…”

Section: Methodsmentioning

confidence: 99%

“…Review guidelines for 4DCT image sets were developed based on commissioning work and experiences from quality assurance for several clinical trials . An in‐house training programme was developed for medical physicists to establish a minimum skillset for performing 4DCT reviews in the context of SABR.…”

Section: Methodsmentioning

confidence: 99%

Independent review of 4DCT scans used for SABR treatment planning

Antony

Lonski

Ungureanu

et al. 2020

J Applied Clin Med Phys

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Four‐dimensional computerized tomography (4DCT) is required for stereotactic ablative body radiotherapy (SABR) of mobile targets to account for tumor motion during treatment planning and delivery. In this study, we report on the impact of an image review quality assurance process performed prior to treatment planning by medical physicists for 4DCT scans used for SABR treatment. Reviews were performed of 211 4DCT scans (193 patients) over a 3‐yr period (October 2014 to October 2017). Treatment sites included lung (n = 168), kidney/adrenal/adrenal gland (n = 12), rib (n = 4), mediastinum (n = 10), liver (n = 2), T‐spine (n = 1), and other abdominal sites (n = 14). It was found that in 23% (n = 49) of cases patient management was altered due to the review process. The most frequent intervention involved patient‐specific contouring advice (n = 35 cases, 17%) including adjustment of internal target volume (ITV) margins. In 13 cases (6%) a rescan was requested due to extensive motion artifact rendering the scan inadequate for SABR treatment planning. 4DCT review by medical physicists was found to be an effective method to improve plan quality for SABR.

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“…When looking at non-continuous volumetric imaging alone (i.e., CBCT), there are a number of reports of endto-end tests exceeding the limits of 1 mm [3,[198][199][200][201], even though the recent COMP report on CBCT advised achieving a geometric accuracy of <1 mm [201]. Hence, the accuracy of CBCT alone may not necessarily be sufficient for SRS, especially when further considering patient motion during treatment (see the "Patient positioning and target volume localization" and "Motion management" sections above).…”

Section: However For Fsrt and Sbrt Close To Radiation-sensitive Critmentioning

confidence: 99%

Technological quality requirements for stereotactic radiotherapy

et al. 2020

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This review details and discusses the technological quality requirements to ensure the desired quality for stereotactic radiotherapy using photon external beam radiotherapy as defined by the DEGRO Working Group Radiosurgery and Stereotactic Radiotherapy and the DGMP Working Group for Physics and Technology in Stereotactic Radiotherapy. The covered aspects of this review are 1) imaging for target volume definition, 2) patient positioning and target volume localization, 3) motion management, 4) collimation of the irradiation and beam directions, 5) dose calculation, 6) treatment unit accuracy, and 7) dedicated quality assurance measures. For each part, an expert review for current state-of-the-art techniques and their particular technological quality requirement to reach the necessary accuracy for stereotactic radiotherapy divided into intracranial stereotactic radiosurgery in one single fraction (SRS), intracranial fractionated stereotactic radiotherapy (FSRT), and extracranial stereotactic body radiotherapy (SBRT) is presented. All recommendations and suggestions for all mentioned aspects of stereotactic radiotherapy are formulated and related uncertainties and potential sources of error discussed. Additionally, further research and development needs in terms of insufficient data and unsolved problems for stereotactic radiotherapy are identified, which will serve as The authors D. Schmitt and O. Blanck contributed equally to the manuscript.

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Credentialing of radiotherapy centres in Australasia for TROG 09.02 (Chisel), a Phase III clinical trial on stereotactic ablative body radiotherapy of early stage lung cancer

Cited by 20 publications

References 36 publications

Technical Note: Small field dose correction factors for radiochromic film in lung phantoms

Technical Note: Small field dose correction factors for radiochromic film in lung phantoms

Independent review of 4DCT scans used for SABR treatment planning

Technological quality requirements for stereotactic radiotherapy

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