Application of the Exradin W1 scintillator to determine Ediode 60017 and microDiamond 60019 correction factors for relative dosimetry within small MV and FFF fields

Underwood, Tracy; Rowland, Ben; Ferrand, R.; Vieillevigne, L.

doi:10.1088/0031-9155/60/17/6669

Cited by 94 publications

(100 citation statements)

References 34 publications

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“…To account for this effect, aČerenkov correction factor (CLR) has been measured following both the procedures suggested by the manufacturer for the different orientations of the scintillating fibre relative to the radiation beam axis. 22,30 Despite the difficulties of the four-step procedure recommended with the scintillator axis is orientated parallel to the beam axis (as mentioned by Underwood et al 24 ), by accurately controlling the positioning of the fibre, we found similar standard deviations, , 1%, which confirm data reported by Carrasco et al 28 , who performed the procedure with the detector perpendicular to the beam axis in plastic water. For convenience, we used the same approach for CLR calibration in the measurement sessions, with the detector perpendicular to the beam axis.…”

Section: Methodssupporting

confidence: 87%

“…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: 85%

“…Consequently, PSDs have just found large application in small-field dosimetry. [21][22][23][24] The main drawback of plastic scintillators is represented by the generation ofČerenkov light in the optical fibre guide when the scintillator is exposed to a radiation field. Two main approaches have been suggested to subtract thě Cerenkov light component: the method proposed by Beddar et al, 15,16 which uses a background optical fibre not coupled with a scintillating fibre, and the two-fibre or spectral method, proposed by Fontbonne et al 25 and reformulated by Guillot et al, 26 which is based on the dependence of the intensity of thě Cerenkov light on the length of the exposed fibre and measures the light signal by means of two different wavelength channels.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Methodssupporting

confidence: 87%

Section: Introductionmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

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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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“…Our measured data agree with results presented by Lechner et al (16) for Elekta linacs where there is minimal deviation in detector measured output factors between FFF and FF fields. Underwood et al (43) determined a similar deviation in small field correction factors for FFF and FF fields for a diode and the PTW microDiamond detector for a Varian linac.…”

Section: Discussionmentioning

confidence: 82%

Small field detector correction factors: effects of the flattening filter for Elekta and Varian linear accelerators

Tyler

Liu

Lee

et al. 2016

J Applied Clin Med Phys

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Flattening filter‐free (FFF) beams are becoming the preferred beam type for stereotactic radiosurgery (SRS) and stereotactic ablative radiation therapy (SABR), as they enable an increase in dose rate and a decrease in treatment time. This work assesses the effects of the flattening filter on small field output factors for 6 MV beams generated by both Elekta and Varian linear accelerators, and determines differences between detector response in flattened (FF) and FFF beams. Relative output factors were measured with a range of detectors (diodes, ionization chambers, radiochromic film, and microDiamond) and referenced to the relative output factors measured with an air core fiber optic dosimeter (FOD), a scintillation dosimeter developed at Chris O'Brien Lifehouse, Sydney. Small field correction factors were generated for both FF and FFF beams. Diode measured detector response was compared with a recently published mathematical relation to predict diode response corrections in small fields. The effect of flattening filter removal on detector response was quantified using a ratio of relative detector responses in FFF and FF fields for the same field size. The removal of the flattening filter was found to have a small but measurable effect on ionization chamber response with maximum deviations of less than ±0.9% across all field sizes measured. Solid‐state detectors showed an increased dependence on the flattening filter of up to ±1.6%. Measured diode response was within ±1.1% of the published mathematical relation for all fields up to 30 mm, independent of linac type and presence or absence of a flattening filter. For 6 MV beams, detector correction factors between FFF and FF beams are interchangeable for a linac between FF and FFF modes, providing that an additional uncertainty of up to ±1.6% is accepted.PACS number(s): 87.55.km, 87.56.bd, 87.56.Da

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“…The MC code was first validated against the square field measurements. There is currently no commercial scanning tank compatible with the PSD, (32) as a two‐channel output system is required to account for the Cerenkov light ratio correction with varying fiber lengths in the field. The Edge diode detector was thus utilized for PDD comparison against MC calculations, while EBT3 film measurements were used for the absolute dose profile comparisons.…”

Section: Resultsmentioning

confidence: 99%

Deriving detector‐specific correction factors for rectangular small fields using a scintillator detector

Qin

Zhong

Snyder

et al. 2016

J Applied Clin Med Phys

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The goal of this study was to investigate small field output factors (OFs) for flattening filter‐free (FFF) beams on a dedicated stereotactic linear accelerator‐based system. From this data, the collimator exchange effect was quantified, and detector‐specific correction factors were generated. Output factors for 16 jaw‐collimated small fields (from 0.5 to 2 cm) were measured using five different detectors including an ion chamber (CC01), a stereotactic field diode (SFD), a diode detector (Edge), Gafchromic film (EBT3), and a plastic scintillator detector (PSD, W1). Chamber, diodes, and PSD measurements were performed in a Wellhofer water tank, while films were irradiated in solid water at 100 cm source‐to‐surface distance and 10 cm depth. The collimator exchange effect was quantified for rectangular fields. Monte Carlo (MC) simulations of the measured configurations were also performed using the EGSnrc/DOSXYZnrc code. Output factors measured by the PSD and verified against film and MC calculations were chosen as the benchmark measurements. Compared with plastic scintillator detector (PSD), the small volume ion chamber (CC01) underestimated output factors by an average of ‐1.0%±4.9%(max.=‐11.7% for 0.5×0.5.2emcm2 square field). The stereotactic diode (SFD) overestimated output factors by 2.5%±0.4%(max.=3.3% for 0.5×1.2emcm2 rectangular field). The other diode detector (Edge) also overestimated the OFs by an average of 4.2%±0.9%(max.=6.0% for 1×1.2emcm2 square field). Gafchromic film (EBT3) measurements and MC calculations agreed with the scintillator detector measurements within 0.6%±1.8% and 1.2%±1.5%, respectively. Across all the X and Y jaw combinations, the average collimator exchange effect was computed: 1.4%±1.1% (CC01), 5.8%±5.4% (SFD), 5.1%±4.8% (Edge diode), 3.5%±5.0% (Monte Carlo), 3.8%±4.7% (film), and 5.5%±5.1% (PSD). Small field detectors should be used with caution with a clear understanding of their behaviors, especially for FFF beams and small, elongated fields. The scintillator detector exhibited good agreement against Gafchromic film measurements and MC simulations over the range of field sizes studied. The collimator exchange effect was found to be important at these small field sizes. Detector‐specific correction factors were computed using the scintillator measurements as the benchmark.PACS number(s): 87.56.Fc

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Application of the Exradin W1 scintillator to determine Ediode 60017 and microDiamond 60019 correction factors for relative dosimetry within small MV and FFF fields

Cited by 94 publications

References 34 publications

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

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

Small field detector correction factors: effects of the flattening filter for Elekta and Varian linear accelerators

Deriving detector‐specific correction factors for rectangular small fields using a scintillator detector

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