Dose response characteristics of new models of GAFCHROMIC films: Dependence on densitometer light source and radiation energy

Chiu‐Tsao, Sou‐Tung; Duckworth, T.; Zhang, Chuanfang; Patel, Neil; Hsiung, Chih-Yun; Wang, Lin; Shih, J. Allen; Harrison, Louis B.

doi:10.1118/1.1767103

Cited by 37 publications

(42 citation statements)

References 49 publications

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“…Post irradiation coloration, also depicted as post exposure growth, is the increase of the optical density of the GafChromic film with time after exposure. Due to post exposure growth it is recommended to scan the films at least 6 h 11,13,25,[32][33][34][35][36] after irradiation. In our study, to avoid different influences of post exposure growth during experiments, film calibration sheets have been scanned simultaneously with the experimental film sheets.…”

Section: Iia Ebt Filmmentioning

confidence: 99%

Accurate dosimetry with GafChromic™ EBT film of a 6MV photon beam in water: What level is achievable?

et al. 2008

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This paper focuses on the accuracy, in absolute dose measurements, with GafChromicTM EBT film achievable in water for a 6 MV photon beam up to a dose of 2.3 Gy. Motivation is to get an absolute dose detection system to measure up dose distributions in a (water) phantom, to check dose calculations. An Epson 1680 color (red green blue) transmission flatbed scanner has been used as film scanning system, where the response in the red color channel has been extracted and used for the analyses. The influence of the flatbed film scanner on the film based dose detection process was investigated. The scan procedure has been optimized; i.e. for instance a lateral correction curve was derived to correct the scan value, up to 10%, as a function of optical density and lateral position. Sensitometric curves of different film batches were evaluated in portrait and landscape scan mode. Between various batches important variations in sensitometric curve were observed. Energy dependence of the film is negligible, while a slight variation in dose response is observed for very large angles between film surface and incident photon beam. Improved accuracy in absolute dose detection can be obtained by repetition of a film measurement to tackle at least the inherent presence of film inhomogeneous construction. We state that the overall uncertainty is random in absolute EBT film dose detection and of the order of 1.3% (1 SD) under the condition that the film is scanned in a limited centered area on the scanner and at least two films have been applied. At last we advise to check a new film batch on its characteristics compared to available information, before using that batch for absolute dose measurements.

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Section: Iia Ebt Filmmentioning

confidence: 99%

Accurate dosimetry with GafChromic™ EBT film of a 6MV photon beam in water: What level is achievable?

et al. 2008

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“…In this film model, the active layer has a thickness of 40 μm and is sandwiched between two clear polyester layers each of 100 μm thickness. The effective atomic number of this film model is 6.5 and the useful dose range of the film is 1-50 Gy (1)(2)(3)(4)(5)(6)(7)(8).…”

Section: Materials and Methods Radiochromic Filmsmentioning

confidence: 99%

Calculation and comparison of MD-55-2 and HS radiochromic films’ responses to the 60Co gamma rays

Abadi¹,

Mowlavi²,

Izadi³

et al. 2012

Arch Oncol

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INTRODUCTIONRadiochromic film was firstly used by McLaughlin for measurement of radiation dose. The active layer in this type of film is composed of microcrystalline monomers which are sensitive to radiation and the film turns progressively blue following exposure to ionizing radiation. Nowadays Gafchromic MD-55-2 and HS film models are widely used in medical applications of dose measurements. Because of its relatively medium sensitivity, the use of Gafchromic MD-55-2 radiochromic film is restricted only to low dose range dosimetry. The HS film was designed for dosimetry of photon beams in high energy range and electron beams with energy higher than 1 MeV (1-8). Pourbeigi, et al. has experimentally evaluated the sensitivity and optical density per dose of a multilayer MD-55-2 film to gamma rays in a Perspex phantom. This study was based on a multilayer technique and by adoption of Task Group No. 55 (TG-55) protocol in the experiments. The results have indicated that the sensitivity of this film type increases with an increase of the number of the film layers (3). In a report by International Specialty Products (ISP) company, the response of the HS radiochromic film to high energy photon beams was compared with that of the two-layer MD-55-2 radiochromic film and it was evident that the response of the HS film was about two-folds higher than that of the MD-55-2 film (5). However, to the best of our knowledge, there are limited reports on sensitivity of the MD-55-2 film to 60 Co gamma photons based on multilayer technique as well as on comparing the response of this type of radiochromic film with the HS film through Monte Carlo simulation of these films. This fact has been a motivation for us to perform the current study. The aim of this study is to evaluate the sensitivity of a multilayer Gafchromic MD-55-2 film and to compare its response to 60 Co gamma photons with that of the HS radiochromic film through Monte Carlo simulation of the films. Furthermore, the effect of type of MCNPX scoring tally on the response of the films was evaluated as well. MATERIALS AND METHODS Radiochromic filmsGafchromic MD-55-2 radiochromic film is composed of two active layers of 13 μm thickness. The active layers are coated on a 25.4 μm polyester base. Each active layer has a protective polyester coating with 67 μm of thickness. Effective atomic number of the film is 6.5 and the film is suitable for measurements in dose range of 3-100 Gy. Gafchromic HS film was presented as a higher sensitivity and uniformity option by development of the MD-55 radiochromic film. In this film model, the active layer has a thickness of 40 μm and is sandwiched between two clear polyester layers each of 100 μm thickness. The effective atomic number of this film model is 6.5 and the useful dose range of the film is 1-50 Gy (1-8).A summary on characteristics of the MD-55-2 and the HS radiochromic films including mass density, thickness of the active layer, thickness of the polyester layer and chemical composition of the films are listed in Table 1. More det...

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“…The EBT appears to be a reasonable candidate for use as an optical media for radiation therapy dosimetry. Several types of densitometers have been used for RCFs [1,2].…”

Section: Introductionmentioning

confidence: 99%

The single emission spectrum densitometry for radiochromic films by flat-bed document scanner with transparency unit employing light emitting diode

Azuma

Aoyama

Goto

2008

2008 IEEE Instrumentation and Measurement Technology Conference

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We developed an infrared flat-bed scanner with a transparency unit iMeasure, Inc.) in order to increase the sensitivity of the measuring density of Radiochromic film, Gafchromic film EBT model. Radiochromic film has been usedfor many years as a two-dimensional radiation detectorfor dosimetry in radiotherapy. One of the commercially available Radiochromic films today is the Gafchromic film EBT model (EBT) manufactured by ISP (International Speciality Products, Wayne, NJ). EBT has the absorption spectrum with a maximum absorption band centered at 636 nm. Consequently the response of EBT will be enhanced by measuring with a red light. The transparency unit of IR-4000 for EBT has a light emitting diode (LED) with apeak wavelength of630 nm, and was produced by replacing a white light in the transparency unit for the flat-bed scanner (ES-2200, Seiko Epson Corp) with the LEDs. IR-4000 could improve the sensitivityfor EBT in all dose ranges. However, we had to consider the methods for decreasing noise. We examinedfor IR-4000 how to keep the high sensitivity and reduce noise. Multiple scans and the reduction ofthe image resolution by pixel averaging, which was effective in noise reduction, were employed. IR-4000 is a useful densitometry device to GAFs since optional transparency units which have various single emission spectra are prepared

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Dose response characteristics of new models of GAFCHROMIC films: Dependence on densitometer light source and radiation energy

Cited by 37 publications

References 49 publications

Accurate dosimetry with GafChromic™ EBT film of a 6MV photon beam in water: What level is achievable?

Accurate dosimetry with GafChromic™ EBT film of a 6MV photon beam in water: What level is achievable?

Calculation and comparison of MD-55-2 and HS radiochromic films’ responses to the 60Co gamma rays

The single emission spectrum densitometry for radiochromic films by flat-bed document scanner with transparency unit employing light emitting diode

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