Determination of the beam quality index of high‐energy photon beams under nonstandard reference conditions

Palmans, Hugo

doi:10.1118/1.4745565

Cited by 23 publications

(29 citation statements)

References 16 publications

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“…It was demonstrated by Sauer that this methodology also works well for nonsquare (e.g., circular or rectangular) fields using the equivalent square fields method (BJR Supplement 25) and even for FFF beams after applying a correction for the scatter deficiency caused by their conical‐shape lateral beam profiles (yielding a virtually flattened equivalent square field size). Based on the same approach and the same BJR Supplement 25 data, Palmans derived self‐consistent formulas for the derivation of TPR 20,10 (10) from TPR 20,10 ( S ) for a narrower range of square field sizes ( S between 4 and 12 cm, the relevant range) as well as for the derivation of % dd (10,10) X from % dd (10, S ) X , the percentage depth dose at 10 cm depth in a water phantom due to photons only (i.e., excluding the contribution of electron contamination) for an equivalent square field size of S cm × S cm at a source‐to‐surface distance (SSD) of 100 cm.…”

Section: Physics Of Small‐field Dosimetrymentioning

confidence: 99%

“…For rectangular and circular fields, IAEA TRS‐483 provides tables to derive their equivalent square msr field sizes, including data for generic FFF beams that are also valid for TomoTherapy and CyberKnife machines . The beam quality specifier is then determined as:

{normalTPR}_{20, 10} false(10 false) = \frac{{normalTPR}_{20, 10} false(S false) + c \cdot false(10 - S false)}{1 + c \cdot (10 - S)},

where c = (16.15 ± 0.12) × 10 −3 , or

% d d false(10, 10 false) = \frac{% d d (10, S) + 80 c \cdot (10 - S)}{1 + c \cdot (10 - S)},

where c = (53.4 ± 1.1) × 10 −3 . It should be noted that if a field is smaller than 4 cm, it cannot be considered to be an msr field for accelerating potentials of 6 MV or higher.…”

Section: Formalism and Applicationmentioning

confidence: 99%

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Dosimetry of small static fields used in external photon beam radiotherapy: Summary of TRS‐483, the IAEA–AAPM international Code of Practice for reference and relative dose determination

Palmans

Andreo

Huq³

et al. 2018

Medical Physics

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Purpose A joint IAEA/AAPM international working group has developed a Code of Practice (CoP) for the dosimetry of small static fields used in external megavoltage photon beam radiotherapy, published by the IAEA as TRS‐483. This summary paper introduces and outlines the main aspects of the CoP. Methods IAEA TRS‐483 is a condensation of the wide range of different approaches that have been described in the literature for the reference dosimetry of radiotherapy machines with nominal accelerating potential up to 10 MV that cannot establish the conventional 10 cm × 10 cm reference field, and for the determination of field output factors for relative dosimetry in small static photon fields. The formalism used is based on that developed by Alfonso et al. [Med Phys. 2008;35:5179–5186] for this modality. Results Three introductory sections describe the rationale and context of the CoP, the clinical use of small photon fields, and the physics of small‐field dosimetry. In the fourth section, definitions of terms that are specific to the CoP (as compared to previous CoPs for broad‐beam reference dosimetry, such as IAEA TRS‐398 and AAPM TG‐51) are given; this section includes a list of the symbols and equivalences between IAEA and AAPM nomenclature to facilitate the practical implementation of the CoP by end users of IAEA TRS‐398 and AAPM TG‐51. The fifth section summarizes the equations and procedures that are recommended in the CoP and the sixth section provides an overview of the methods used to derive the data provided in IAEA TRS‐483. Conclusions This is the first time an international Code of Practice for the dosimetry of small photon fields based on comprehensive data and correction factors has been published. This joint IAEA/AAPM CoP will ensure consistent reference dosimetry traceable to the international System of Units and enable common and internationally harmonized procedures to be followed by radiotherapy centers worldwide for the dosimetry of small static megavoltage photon fields.

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Section: Physics Of Small‐field Dosimetrymentioning

confidence: 99%

{normalTPR}_{20, 10} false(10 false) = \frac{{normalTPR}_{20, 10} false(S false) + c \cdot false(10 - S false)}{1 + c \cdot (10 - S)},

where c = (16.15 ± 0.12) × 10 −3 , or

% d d false(10, 10 false) = \frac{% d d (10, S) + 80 c \cdot (10 - S)}{1 + c \cdot (10 - S)},

where c = (53.4 ± 1.1) × 10 −3 . It should be noted that if a field is smaller than 4 cm, it cannot be considered to be an msr field for accelerating potentials of 6 MV or higher.…”

Section: Formalism and Applicationmentioning

confidence: 99%

Dosimetry of small static fields used in external photon beam radiotherapy: Summary of TRS‐483, the IAEA–AAPM international Code of Practice for reference and relative dose determination

Palmans

Andreo

Huq³

et al. 2018

Medical Physics

Self Cite

242

445

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show abstract

“…TPR 20,10 (10) or % dd (10,10) are derived from the following equations, valid for 4 cm ≤ S ≤ 12 cm, with S being the equivalent square msr field size:

T P R_{20, 10} false(10 false) = \frac{T P R_{20, 10} false(S false) + c false(10 - S false)}{1 + c (10 - S)}

where c = (16.15 ± 0.12) × 10 −3 , or

% d d false(10, 10 false) = \frac{% d d (10, S) + 80 c (10 - S)}{1 + c (10 - S)}

where c = (53.4 ± 1.1) × 10 −3 . These expressions were derived by Palmans . It should be noted that Sauer first proposed a solution for the determination of TPR 20,10 (10) from measured values of TPR 20,10 ( S ) for different field sizes .…”

Section: Overview Of the Formalism For Reference And Relative Dosimetmentioning

confidence: 99%

A dosimetric evaluation of the IAEA‐AAPM TRS483 code of practice for dosimetry of small static fields used in conventional linac beams and comparison with IAEA TRS‐398, AAPM TG51, and TG51 Addendum protocols

et al. 2018

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“…Scott et al [16] have suggested that one set of correction factors could be calculated for a wide range of linacs, despite variations in beam quality with linac type and field size [18] aim of this study was to develop a mathematical relation from experimental data that predicts the magnitude of diode overresponse in a range of linacs. The mathematical relation was validated by comparison with the correction factors available in the literature [5][6][7][8]13,15,14,11].…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Can small field diode correction factors be applied universally?

Liu

Suchowerska

McKenzie

2014

Radiotherapy and Oncology

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Determination of the beam quality index of high‐energy photon beams under nonstandard reference conditions

Abstract: The models proposed here can be used in practical recommendations for the dosimetry of small and nonstandard fields.

Cited by 23 publications

References 16 publications

Dosimetry of small static fields used in external photon beam radiotherapy: Summary of TRS‐483, the IAEA–AAPM international Code of Practice for reference and relative dose determination

Dosimetry of small static fields used in external photon beam radiotherapy: Summary of TRS‐483, the IAEA–AAPM international Code of Practice for reference and relative dose determination

A dosimetric evaluation of the IAEA‐AAPM TRS483 code of practice for dosimetry of small static fields used in conventional linac beams and comparison with IAEA TRS‐398, AAPM TG51, and TG51 Addendum protocols

Can small field diode correction factors be applied universally?

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