The use of GAFchromic film to determine the absolute activity of beta emitters

Ra, Fox; Barker, P; Smart, G

doi:10.1088/0031-9155/44/4/002

Cited by 11 publications

(4 citation statements)

References 9 publications

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“…The expected dose in table 1 has been corrected by the dose loss in various materials between the source and the sensitive film For the loss of β dose in the film substrate itself, the correction fraction was determined to be 20.0%. This value is higher than that obtained by Fox et al (1999) who calculated the correction fraction to be approximately 17% using the dose point kernel method. However, it does not appear that they have made an allowance for the greater density of ∼1.22 g cm −3 of the GAFchromic film.…”

Section: Comparison Between Measured and Expected Dosescontrasting

confidence: 69%

Dose measurement based on spectral chi-square minimization using GAFchromic MD-55 film

Chan

Prestwich

2000

Phys. Med. Biol.

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A new method of measuring dose using GAFchromic MD-55-2 type film is proposed. It involves 2D fitting of optical density, as a function of both wavelength and dose, to a set of measured calibration data. An unknown dose to a film can then be determined by minimizing the chi-square between the measured optical densities and the fitted calibration data. The methodology was tested, using 60Co calibration, by measuring the dose deposited in films irradiated by a 32p source in a semi-infinite geometry. The results are compared with the expected dose obtained From beta counting, taking into account the dose loss correction due to various attenuating materials, including the film substrate itself, which was determined to be 20%. It was found that the root mean relative deviation between the measured and expected doses was approximately 3%. The excellent agreement also demonstrated the possibility of calibration between gamma and beta particles.

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Section: Comparison Between Measured and Expected Dosescontrasting

confidence: 69%

Dose measurement based on spectral chi-square minimization using GAFchromic MD-55 film

Chan

Prestwich

2000

Phys. Med. Biol.

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“…25 In addition, radiochromic film has been employed for the measurement of the absolute activity for high-energy beta emitters. 26 The dosimetric approach of using radiochromic film may be suitable for our aim of measuring beta absorbed doses due to its inherently high spatial resolution, minimal absorbed dose rate and energy independence, and its near tissue equivalence from an atomic composition standpoint.…”

Section: Introductionmentioning

confidence: 99%

“…In the last few years, radiochromic film has been used for verification of external beam dosimetric accuracy, 22 for IMRT dose verification, 23 feasibility of alpha‐particle dosimetry, 24 and dose calibration for Ir‐192 brachytherapy 25 . In addition, radiochromic film has been employed for the measurement of the absolute activity for high‐energy beta emitters 26 . The dosimetric approach of using radiochromic film may be suitable for our aim of measuring beta absorbed doses due to its inherently high spatial resolution, minimal absorbed dose rate and energy independence, and its near tissue equivalence from an atomic composition standpoint.…”

Section: Introductionmentioning

confidence: 99%

Absorbed dose distributions from beta‐decaying radionuclides: Experimental validation of Monte Carlo tools for radiopharmaceutical dosimetry

et al. 2020

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Purpose This study aims to experimentally validate the Monte Carlo generated absorbed doses from the beta particles emitted by 90Y and 177Lu using radiochromic EBT3 film‐based dosimetry. Methods Line sources of 90Y and 177Lu were inserted longitudinally through blocks of low‐density polyethylene and tissue‐equivalent slabs of cortical bone and lung equivalent plastics. Radiochromic film (Gafchromic EBT3) was laser cut to accommodate orthogonal line sources of radioactivity, and the film was sandwiched intimately between the rectangular blocks to achieve charged particle equilibrium. Line sources consisted of plastic capillary tube of length (13 ± 0.1) cm, with 0.42‐mm inner diameter and a wall thickness of 0.21 mm. 90Y line sources were prepared from a solution of dissolved 90Y resin microspheres. 177Lu line sources were prepared from an aliquot of 177Lu‐DOTATATE. Film exposures were conducted for durations ranging from 10 min to 38 h. Radiochromic film calibration was performed by irradiation with 6‐MV‐bremsstrahlung x rays from a calibrated linear accelerator, in accordance with literature recommendations. Experimental geometries were precisely simulated within the GATE Monte Carlo toolkit, which has previously been used for the generation of dose point kernels. Results The mean percentage difference between measured and simulated absorbed doses were 5.04% and 7.21% for 90Y and 177Lu beta absorbed dose in the range of (0.1–10) Gy. Additionally, 1D gamma analysis using a local 10%/1 mm gamma criterion was performed to compare the absorbed dose distributions. The percentage of measurement points passing the gamma criterion, averaged over all tests, was 93.5%. Conclusions We report the experimental validation of Monte Carlo derived beta absorbed dose distributions for 90Y and 177Lu, solidifying the validity of using Monte Carlo‐based methods for estimating absorbed dose from beta emitters. Overall, excellent agreement was observed between the experimental beta absorbed doses in the linear region of the radiochromic film and the GATE Monte Carlo simulations demonstrating that radiochromic film dosimetry has sufficient sensitivity and spatial resolution to be used as a tool for measuring beta decay absorbed dose distributions.

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“…RCFs need to be read out before any quantitative analysis of the absorbed doses can be made. Existing readout methods include spectrophotometry (Saylor et al 1988, Klassen et al 1997, Fox et al 1999, Cheung et al 2001 and densitometry using analysing light sources such as a laser, fluorescent lamp and light-emitting diode (Niroomand-Rad et al 1998, Ertl et al 1999, Odero et al 2001, Cheung et al 2002. Commercial document and film scanners in monochrome or colour mode (Stevens et al 1996, Bazioglou and Kalef-Ezra 2001, Aydarous et al 2001, Alva et al 2002 have also been used as readout devices for RCFs.…”

Section: Introductionmentioning

confidence: 99%

Development and initial evaluation of a spectral microdensitometer for analysing radiochromic films

Lee¹,

Fung²,

Kwok³

2004

Phys. Med. Biol.

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Radiation dose deposited on a radiochromic film is considered as a dose image. A precise image extraction system with commensurate capabilities is required to measure the transmittance of the image and translate it to radiation dose. This paper describes the development of a spectral microdensitometer which has been designed to achieve this goal under the conditions of (a) the linearity and sensitivity of the dose response curve of the radiochromic film being highly dependent on the wavelength of the analysing light, and (b) the inherent high spatial resolution of the film. The microdensitometer consists of a monochromator which provides an analysing light of variable wavelength, a film tray on a high-precision scanning stage, a transmission microscope coupled to a thermoelectrically cooled CCD camera, a microcomputer and corresponding interfaces. The measurement of the transmittance of the radiochromic film is made at the two absorption peaks with maximum sensitivities. The high spatial resolution of the instrument, of the order of micrometres, is achieved through the use of the microscope combined with a measure-and-step technique to cover the whole film. The performance of the instrument in regard to the positional accuracy, system reproducibility and dual-peak film calibration was evaluated. The results show that the instrument fulfils the design objective of providing a precise image extraction system for radiochromic films with micrometre spatial resolution and sensitive dose response.

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The use of GAFchromic film to determine the absolute activity of beta emitters

Cited by 11 publications

References 9 publications

Dose measurement based on spectral chi-square minimization using GAFchromic MD-55 film

Dose measurement based on spectral chi-square minimization using GAFchromic MD-55 film

Absorbed dose distributions from beta‐decaying radionuclides: Experimental validation of Monte Carlo tools for radiopharmaceutical dosimetry

Development and initial evaluation of a spectral microdensitometer for analysing radiochromic films

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