Experimental small field 6MV output ratio analysis for various diode detector and accelerator combinations

Cranmer-Sargison, Gavin; Weston, S.; Sidhu, Narinder; Thwaites, David

doi:10.1016/j.radonc.2011.09.002

Cited by 53 publications

(45 citation statements)

References 24 publications

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“…Diode E value is 1.8% larger than recommended and is practically same as value measured by Mack et al [13]. Several authors reported over-response of shielded and unshielded silicon detectors in small photon fields [20,21,23]. It was proposed that formalism for reference dosimetry of small and nonstandard fields should be applied for correction of output factors in that case [19,24e26].…”

Section: Corrected Output Factorssupporting

confidence: 52%

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Correction of measured Gamma-Knife output factors for angular dependence of diode detectors and PinPoint ionization chamber

et al. 2014

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Section: Corrected Output Factorssupporting

confidence: 52%

“…A silicon detector will over-respond to low-energy scattered photons due to photoelectric effect in silicon sensitive volume [20]. To reduce this effect in the Diode P a disk-shaped silicon chip is surrounded by metal shielding.…”

Section: Detectorsmentioning

confidence: 99%

Correction of measured Gamma-Knife output factors for angular dependence of diode detectors and PinPoint ionization chamber

et al. 2014

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“…3,6,11,12 Silicon detectors have a very high resolution; typically, unshielded p-type silicon diodes with very small active volume are used to perform small-field dosimetric characterization and output factor (OF) measurements. 13 However, the mass density of the sensitive volume and surrounding medium strongly influences the small-field measurements with ionization microchambers and diodes. 9,14 Owing to their water equivalence and good spatial resolution, plastic scintillation detectors (PSDs) could play an important role in small-field dosimetry.…”

Section: Introductionmentioning

confidence: 99%

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 factor of a radiation field is defined as the ratio of the absorbed dose in water at a point located at the isocentre for the given field, relative to that at the same point in the reference field. In small fields, the measurement of the output factor is subject to large uncertainties [2].Silicon diode detectors are commonly used in small field dosimetry due to their relatively small sensitive volumes and their high radiosensitivity. However in the measurement of output factors, diodes have been reported to over-respond in small fields.…”

mentioning

confidence: 99%

Can small field diode correction factors be applied universally?

Liu

Suchowerska

McKenzie

2014

Radiotherapy and Oncology

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Experimental small field 6MV output ratio analysis for various diode detector and accelerator combinations

Cited by 53 publications

References 24 publications

Correction of measured Gamma-Knife output factors for angular dependence of diode detectors and PinPoint ionization chamber

Correction of measured Gamma-Knife output factors for angular dependence of diode detectors and PinPoint ionization chamber

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

Can small field diode correction factors be applied universally?

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