Accuracy of GafChromic EBT Film as Dose Meter in Radiotherapy QA

Battum, L. van; Hoffmans, D.; Kwa, Stefan L.S.; Heukelom, S.

doi:10.1007/978-3-642-03474-9_30

Cited by 3 publications

(4 citation statements)

References 7 publications

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“…Because EBT2 film partially polarizes transmitted light, 22 the doses calculated using images from a CCD scanner may show substantial lateral distortions. 16,20,21,23 The multichannel technique is able to mitigate this lateral dependence. To demonstrate this, one of the EBT2 films exposed to a 10 m Â 10 cm field and used to generate the calibration curve shown in Table I was scanned in the center of an Epson 10000XL scanner and then moved to a new position displaced "4" laterally from the center of the scanner and rescanned a position close to the left edge of the scan window.…”

Section: Iiid Mitigation Of Lateral Displacement Effectmentioning

confidence: 99%

“…A multichannel scanner provides a choice of colors for scanning and this has been useful in offering the selection of the red color channel for greater sensitivity at lower doses, yet being able to extend the dynamic range of the film to much higher doses using the green of blue channels. [6][7][8][9]13 However, a number of investigators 11,12,14,15,21 have pointed to challenges in radiochromic film dosimetry, particularly those related to the scanning of the radiochromic film. To date, radiochromic film dosimetry has relied on the use of information from a single color channel of an red-bluegreen (RGB) scanner.…”

Section: Introductionmentioning

confidence: 99%

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Multichannel film dosimetry with nonuniformity correction

2011

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Section: Iiid Mitigation Of Lateral Displacement Effectmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Multichannel film dosimetry with nonuniformity correction

2011

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“…Our institution has vast experience in film dosimetry for dosimetric plan QA and end-to-end testing (van Battum et al 2008(van Battum et al , 2009(van Battum et al , 2016. EBT3 GafChromic film (Ashland Inc.) is a suitable tool for absolute 2D measurement of photon beams.…”

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confidence: 99%

Suitability of EBT3 GafChromic film for quality assurance in MR-guided radiotherapy at 0.35 T with and without real-time MR imaging

et al. 2018

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The 0.35 T Co MRIdian system (ViewRay Inc., Mountain View) has been in clinical use in our institution since May 2016. For quality assurance (QA) of dose delivery and end-to-end testing for this machine, a reliable dosimeter is required. However, it is possible that a magnetic field may cause perturbations to dosimetry measurements. For static magnetic fields, there is conflicting information in the literature concerning EBT film behaviour, while for real-time MR imaging such information is not available at all. The purpose of this study was to investigate the suitability of EBT3 GafChromic film for MRIdian QA, both with and without real-time MR imaging. EBT3 film sheets were irradiated in water using the MRIdian and a conventional linear accelerator (Linac) for reference. Dose calibration measurements were first performed up to 8 Gy for both machines. The MRIdian measurements were performed with and without real-time MR imaging. Second, film sheets were irradiated at seven different angles with respect to the B-field. Optical density and dose values were analysed for the three colour channels. In both the film dose-response and B-field orientation measurements, the mean dose values were within the 1% uncertainty range of prescribed dose values for the red and green channels, for both machines. There were no dose deviations detected between the MRIdian and Linac film measurements, nor for different B-field orientations. In addition, the film dose-response measurements during real-time imaging were within 1.5% of the reference Linac measurements. EBT3 GafChromic film can be used for absolute dosimetry during real-time MR imaging independent of its orientation in the B-field. This makes it a suitable dosimeter for patient-specific QA measurements and end-to-end testing of 0.35 T MRI-radiotherapy devices.

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“…Films were digitized using a transmission flatbed scanner (Epson Expression 1680 Pro). All films were scanned in portrait mode along the central axis of the scanner in order to avoid lateral scanner artifacts (Battum and Hoffmans 2009). Film transmission values were translated to absolute dose (DOSE FILM ) by means of a triple-color calibration method and generating a calibration curve with Matlab (R2015b, Mathworks) (Mayer et al 2012).…”

Section: Film Dosimetrymentioning

confidence: 99%

An end-to-end test for MR-guided online adaptive radiotherapy

et al. 2020

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In the evolving field of adaptive MR guided radiotherapy, the need for dedicated procedures for acceptance and quality assurance is increasing. Research has been devoted to MR compatible dosimeters and phantoms, but to date no end-to-end test has been presented that covers an MRgRT workflow. Such an end-to-end test should comprise each step of the workflow and include all associated uncertainties. The purpose of this study was to investigate the usability of an anthropomorphic deformable and multimodal pelvis (ADAM-pelvis) phantom in combination with film dosimetry for end-to-end testing of an MRgRT adaptive workflow. The ADAM-pelvis phantom included surrogates for muscle tissue, adipose and bone, as well as deformable silicone organs mimicking a prostate patient. At the interfaces of the critical structures (bladder and rectum), small pieces of GafChromic EBT3 films were placed to measure delivered dose. Pre-treatment MR imaging of the phantom was used to delineate the prostate, rectum and bladder and to generate a treatment plan to deliver 2 Gy to the prostate. Electron density (ED) map from CT imaging was used for dose calculation after deformable image registration (DIR) to the pre-treatment MR scan. At each fraction, bladder- and rectum filling was varied and a new adapted plan was generated. Dose calculation was performed using both a DIR-based ED map and a CT-based ED map after acquisition of a new CT scan of the phantom at each fraction. All dose calculations were performed taking into account the magnetic field. A good agreement between measured and calculated dose was found using both, the CT-derived and the DIR-based ED map (2.0% and 2.8% dose difference, respectively). The gamma index pass-rate (3%/2 mm) varied from 96.4% to 100%.The ADAM-pelvis phantom was suitable for end-to-end testing in MR-guided radiotherapy and a very good agreement with the calculated dose was achieved.

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Accuracy of GafChromic EBT Film as Dose Meter in Radiotherapy QA

Cited by 3 publications

References 7 publications

Multichannel film dosimetry with nonuniformity correction

Multichannel film dosimetry with nonuniformity correction

Suitability of EBT3 GafChromic film for quality assurance in MR-guided radiotherapy at 0.35 T with and without real-time MR imaging

An end-to-end test for MR-guided online adaptive radiotherapy

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