Correction factor measurements for multiple detectors used in small field dosimetry on the Varian Edge radiosurgery system

Tanny, S; Sperling, N; Parsai, E

doi:10.1118/1.4928602

Cited by 43 publications

(46 citation statements)

References 48 publications

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“…In addition the differences between accelerator manufacturers, as well as different models produced by the same vendor, can contribute to different energy spectra, even if mechanical components are the same. Tanny et al (25) reported a

k_{Q_{italicclin}, Q_{italicmsr}}^{f_{italicclin}, f_{italicmsr}}

correction factor study using multiple detectors, including the Edge diode detector, for Varian TrueBeam with flattening filter‐free energies of 6 MV (6 MV‐FFF) and 10 MV (10 MV‐FFF). Measurements of square field sizes from

6 \times 6 {mm}^{2}

5 \times 5 {cm}^{2}

with the Edge detector were compared to measurements from Exradin W1 scintillating fiber optic dosimeter manufactured by Standard Imaging.…”

Section: Discussionmentioning

confidence: 99%

“…However, for 10 MV, the Edge output factors are significantly lower than MC results for cone diameters of 7.5 mm and less. One possible source of error which may explain this is that the correction factors for 4 mm and 5 mm were extrapolated from data by Tanny et al (25) and not actually measured. Another possible source of error is the different measurement conditions utilized by our study, relative to the one by Tanny and colleagues.…”

Section: Discussionmentioning

confidence: 99%

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Output factor comparison of Monte Carlo and measurement for Varian TrueBeam 6 MV and 10 MV flattening filter‐free stereotactic radiosurgery system

Cheng

Ning

Arora

et al. 2016

J Applied Clin Med Phys

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The dose measurements of the small field sizes, such as conical collimators used in stereotactic radiosurgery (SRS), are a significant challenge due to many factors including source occlusion, detector size limitation, and lack of lateral electronic equilibrium. One useful tool in dealing with the small field effect is Monte Carlo (MC) simulation. In this study, we report a comparison of Monte Carlo simulations and measurements of output factors for the Varian SRS system with conical collimators for energies of 6 MV flattening filter‐free (6 MV) and 10 MV flattening filter‐free (10 MV) on the TrueBeam accelerator. Monte Carlo simulations of Varian's SRS system for 6 MV and 10 MV photon energies with cones sizes of 17.5 mm, 15.0 mm, 12.5 mm, 10.0 mm, 7.5 mm, 5.0 mm, and 4.0 mm were performed using EGSnrc (release V4 2.4.0) codes. Varian's version‐2 phase‐space files for 6 MV and 10 MV of TrueBeam accelerator were utilized in the Monte Carlo simulations. Two small diode detectors Edge (Sun Nuclear) and Small Field Detector (SFD) (IBA Dosimetry) were applied to measure the output factors. Significant errors may result if detector correction factors are not applied to small field dosimetric measurements. Although it lacked the machine‐specific kQitalicclin,Qitalicmsrfitalicclin,fitalicmsr correction factors for diode detectors in this study, correction factors were applied utilizing published studies conducted under similar conditions. For cone diameters greater than or equal to 12.5 mm, the differences between output factors for the Edge detector, SFD detector, and MC simulations are within 3.0% for both energies. For cone diameters below 12.5 mm, output factors differences exhibit greater variations.PACS number(s): 87.55.k, 87.55.Qr

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k_{Q_{italicclin}, Q_{italicmsr}}^{f_{italicclin}, f_{italicmsr}}

6 \times 6 {mm}^{2}

5 \times 5 {cm}^{2}

with the Edge detector were compared to measurements from Exradin W1 scintillating fiber optic dosimeter manufactured by Standard Imaging.…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Output factor comparison of Monte Carlo and measurement for Varian TrueBeam 6 MV and 10 MV flattening filter‐free stereotactic radiosurgery system

Cheng

Ning

Arora

et al. 2016

J Applied Clin Med Phys

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“…The results are compared with those obtained with other detectors we already use for small photon beam dosimetry, contributing to complement data that can be found in the literature, 24,[27][28][29] in particular regarding the behaviour of these detectors in smallfield beam dosimetry required for TPS commissioning (PDD, dose profile and OF measurements).…”

Section: Introductionmentioning

confidence: 90%

Dosimetric characterization and behaviour in small X-ray fields of a microchamber and a plastic scintillator detector

Pasquino

Cutaia

Radici

et al. 2017

BJR

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Objective: The aim of this work was to investigate the main dosimetric characteristics and the performance of an A26 Exradin ionization microchamber (A26 IC) and a W1 Exradin plastic scintillation detector (W1 PSD) in small photon beam dosimetry for treatment planning system commissioning and quality assurance programme. Methods: Detector characterization measurements (short-term stability, dose linearity, angular dependence and energy dependence) were performed in water for field sizes up to 10 3 10 cm 2 . Polarity effect (P pol ) was examined for the A26 IC. The behaviour of the detectors in small field relative dosimetry [percentage depth dose, dose profiles often called the off-axis ratio and output factors (OFs)] was investigated for field sizes ranging from 1 3 1 to 3 3 3 cm 2 . Results: Results were compared with those obtained with other detectors we already use for small photon beam dosimetry. A26 IC and W1 PSD showed a linear dose response. While the A26 IC showed no energy dependence, the W1 PSD showed energy dependence within 2%; no angular dependence was registered. P pol values for A26 IC were below 0.9% (0.5% for field size .2 3 2 cm 2 ). A26 IC and W1 PSD depth-dose curves and lateral profiles agreed with those obtained with an EDGE diode. No differences were observed among the detectors in OF measurement for field sizes larger than 1 3 1 cm 2 , with average differences ,1%. For field sizes ,1 3 1 cm 2 , the effective volume of ionization chamber and non-water equivalence of EDGE diode become significant. A26 IC OF values were significantly lower than EDGE diode and W1 PSD values, with percentage differences of about 223 and 213% for the smallest field, respectively. W1 PSD OF values lay between ion chambers and diode values, with a maximum percentage difference of about 210% with respect to the EDGE diode, for a 6 3 6-mm 2 field size. Conclusion: The results of our investigation confirm that A26 IC and W1 PSD could play an important role in small field relative dosimetry. Advances in knowledge: Dosimetric characteristics of Exradin A26 ionization microchamber and W1 plastic scintillation detector for small field dosimetry.

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“…The output correction factor takes into account all the small‐field effects that have an impact on the output factor, such as partial volume averaging, atomic number, density and detector shielding. The new formalism was followed by a series of scientific papers providing numerical values of the correction factors for several beam quality, field size and detector combinations . Correction factors for most available radiotherapy and radiosurgery techniques (e.g., linear accelerators, CyberKnifes and Gamma Knifes) and modern radiation detectors (e.g., ionization chambers and solid‐state detectors) can be found in the cited papers.…”

Section: Introductionmentioning

confidence: 99%

Spectral distribution of particle fluence in small field detectors and its implication on small field dosimetry

Benmakhlouf

Andreo

2017

Medical Physics

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The present work improves the understanding of small-field effects by relating output correction factors to spectral fluence perturbations in small field detectors. It is shown that the main reasons for the well-known small-field effects in silicon diodes are the high-Z and density of the "extracameral" detector components and the high I-value of silicon relative to that of water and diamond. Compared to these parameters, the density and atomic number of the radiation sensitive volume material play a less significant role.

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Correction factor measurements for multiple detectors used in small field dosimetry on the Varian Edge radiosurgery system

Cited by 43 publications

References 48 publications

Output factor comparison of Monte Carlo and measurement for Varian TrueBeam 6 MV and 10 MV flattening filter‐free stereotactic radiosurgery system

Output factor comparison of Monte Carlo and measurement for Varian TrueBeam 6 MV and 10 MV flattening filter‐free stereotactic radiosurgery system

Dosimetric characterization and behaviour in small X-ray fields of a microchamber and a plastic scintillator detector

Spectral distribution of particle fluence in small field detectors and its implication on small field dosimetry

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