Absorption spectra variations of EBT radiochromic film from radiation exposure

Butson, Martin J; Cheung, Tsang; Yu, Peter K N

doi:10.1088/0031-9155/50/13/n02

Cited by 97 publications

(90 citation statements)

References 11 publications

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“…Its sensitivity is 10 times larger than its predecessors, such as GafChromic MD‐55–2 and HS. The useful dose range is from 1 to 800 cGy, and presents two absorption peaks at 636 and 585 nm, (12) its response is energy independent, (13) and according to the manufacturer specifications, it has a real time response.…”

Section: Methodsmentioning

confidence: 99%

Radiation transmission, leakage and beam penumbra measurements of a micro‐multileaf collimator using GafChromic EBT film

García‐Garduño

Celis

Lárraga‐Gutiérrez

et al. 2008

J Applied Clin Med Phys

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Micro‐multileaf collimator systems coupled to linear accelerators for radioneurosurgery treatments require a rigorous dosimetric characterization in order to be used in 3D conformal and intensity modulated stereotactic radiosurgery and radiotherapy applications. This characterization involves high precision measurements of leaf transmission, leakage and beam penumbra through the collimation system and requires the use of detectors with high spatial resolution, high sensitivity and practically no energy dependence. In this work the use of GafChromic EBT radiochromic film to measure the basic dosimetric properties of the m3‐mMLC (BrainLAB, Germany) micro‐multileaf collimator system integrated to a 6 MV linear accelerator, is reported. Results show that average values of transmission and leakage radiation are 0.93±0.05% and 1.08±0.08%, respectively. The 80–20% beam penumbra were found to be 2.26±0.11 mm along the leaf side (perpendicular to leaf motion) and 2.31±0.11 mm along the leaf end (parallel to leaf motion) using square field sizes ranging from 9.1 to 1.8 cm. These measurements are in agreement with values reported in the literature for the same type of mMLC using different radiation detectors.PACS number: 87.56.N‐

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Section: Methodsmentioning

confidence: 99%

Radiation transmission, leakage and beam penumbra measurements of a micro‐multileaf collimator using GafChromic EBT film

García‐Garduño

Celis

Lárraga‐Gutiérrez

et al. 2008

J Applied Clin Med Phys

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“…The films have been scanned both pre and post cutting to measure any deviations in the optical density of the film caused by the cutting. The Gafchromic film has been analysed using a PC desktop scanner and Image J software [13] as well as a Shimadzu UV-160 UV-visible recording spectrophotometer [14]. The film was left for at least 6 hours before analysis to minimize effects from post irradiation colouration [15].…”

Section: Methodsmentioning

confidence: 99%

Does mechanical pressure on radiochromic film affect optical absorption and dosimetry?

Butson

Cheung

2006

Australas. Phys. Eng. Sci. Med.

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EBT Gafchromic film, a new high sensitivity radiochromic film has been tested to evaluate if external pressure on the film can affect absorption spectra analysis and thus radiation dosimetry. This question arises from the fact that Gafchromic film is often cut into smaller pieces or to certain shapes for dosimetric analysis using scissors which can apply significant pressure to the sides of the film and small film pieces are placed within a solid phantom at depth which can produce significant pressure on the film if appropriate weight distribution procedures are not performed. As expected, results have shown that films cut by scissors can produce a large increase in OD near the film edge up to 5-10 mm away due to physical damage to the EBT film layers. Films placed within a solid phantom receiving up to 39.5 kg/cm2 pressure showed negligible differences in measured absorption spectra compared with control films subject to no external pressure. This equates to negligible external pressure effects for as much as 44 cm of 30 cm x 30 cm solid water placed on a 1 cm2 area film piece. As such, we recommend based on results herein, that film analysis should be performed with a boundary around every film edge, which can be defined visually based in the film. Also film dosimetry in a phantom can be performed with weights up to 39.5 kg/cm2 (or 44 cm of 30 cm x 30 cm solid water or equivalent) placed on the film without effecting the absorption spectra and thus dosimetry of radiation beams.

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“…Recently, a highsensitivity radiochromic film ͑Gafchromic EBT͒ was introduced that has OD sensitivity similar to the radiographic Kodak EDR-2 film. [104][105][106][107][108][109][110][111][112] The current fabrication process for EBT film places the radiation sensitive layer within the substrate in such a way that the measured OD can be a strong function of the film orientation. 113 Laser densitometers are not recommended for use with the film because the crystalline structure for this type of film has changed from that of previous films, causing polarization artifacts and lead to a steep orientation dependence of OD response.…”

Section: Iib1 Filmmentioning

confidence: 99%

Dosimetry tools and techniques for IMRT

et al. 2011

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Intensity modulated radiation therapy ͑IMRT͒ poses a number of challenges for properly measuring commissioning data and quality assurance ͑QA͒ radiation dose distributions. This report provides a comprehensive overview of how dosimeters, phantoms, and dose distribution analysis techniques should be used to support the commissioning and quality assurance requirements of an IMRT program. The proper applications of each dosimeter are described along with the limitations of each system. Point detectors, arrays, film, and electronic portal imagers are discussed with respect to their proper use, along with potential applications of 3D dosimetry. Regardless of the IMRT technique utilized, some situations require the use of multiple detectors for the acquisition of accurate commissioning data. The overall goal of this task group report is to provide a document that aids the physicist in the proper selection and use of the dosimetry tools available for IMRT QA and to provide a resource for physicists that describes dosimetry measurement techniques for purposes of IMRT commissioning and measurement-based characterization or verification of IMRT treatment plans. This report is not intended to provide a comprehensive review of commissioning and QA procedures for IMRT. Instead, this report focuses on the aspects of metrology, particularly the practical aspects of measurements that are unique to IMRT. The metrology of IMRT concerns the application of measurement instruments and their suitability, calibration, and quality control of measurements. Each of the dosimetry measurement tools has limitations that need to be considered when incorporating them into a commissioning process or a comprehensive QA program. For example, routine quality assurance procedures require the use of robust field dosimetry systems. These often exhibit limitations with respect to spatial resolution or energy response and need to themselves be commissioned against more established dosimeters. A chain of dosimeters, from secondary standards to field instruments, is established to assure the quantitative nature of the tests. This report is intended to describe the characteristics of the components of these systems; dosimeters, phantoms, and dose evaluation algorithms. This work is the report of AAPM Task Group 120.

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Absorption spectra variations of EBT radiochromic film from radiation exposure

Cited by 97 publications

References 11 publications

Radiation transmission, leakage and beam penumbra measurements of a micro‐multileaf collimator using GafChromic EBT film

Radiation transmission, leakage and beam penumbra measurements of a micro‐multileaf collimator using GafChromic EBT film

Does mechanical pressure on radiochromic film affect optical absorption and dosimetry?

Dosimetry tools and techniques for IMRT

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