open access

Vol 25, No 1 (2020)
Published online: 2020-01-01
Submitted: 2019-03-13
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Energy and dose dependence of GafChromic EBT3-V3 film across a wide energy range

Sarah Bassi, Donal Cummins, Patrick McCavana
DOI: 10.1016/j.rpor.2019.12.007
·
Rep Pract Oncol Radiother 2020;25(1):60-63.

open access

Vol 25, No 1 (2020)
Published online: 2020-01-01
Submitted: 2019-03-13

Abstract

Aim

To determine the energy and dose dependence of GafChromic EBT3-V3 film over an energy range 0.2 mm Al HVL to 6 MV.

Background

The decay scheme of a brachytherapy source may be complex and the spectrum of energy can be wide. LiF TLDs are the golden standard recommended for dosimetric measures in brachytherapy, for their energy independence, but TLDs could be not available in some centres. An alternative way to perform dose measurements is to use GafChromic films, but they show energy dependence.

Methods and materials

Films have been irradiated at increasing dose with three different beams: 6 MV beam, TPR20, 10 = (0.684 ± 0.01), HVL = (2.00 ± 0.01)mmAl and HVL = (0.20 ± 0.01)mmAl. Calibration curves were generated using the same dose range (0cGy to 850cGy) for the three energies. Using the 6 MV calibration curve as reference, the film response in terms of net optical density (OD) was evaluated.

Results

The difference in the calibration curve obtained by irradiating the film with 6 MV and 2 mm Al HVL energy beams is less than 3 %, within the calibration uncertainty, in the dose range 500-850cGy. The OD of EBT3-V3 film is significantly lower at 0.2 mmAl HVL compared to 6 MV, showing differences up to 25 %.

Conclusion

Within the range 6 MV-2 mm Al HVL and dose higher than 500cGy, GafChromic EBT3-V3 films are energy independent. In this dose range, films can be calibrated in a simple geometry, using a 6 MV Linac beam, and can be used for brachytherapy sources dose measures. The use of EBT3 films can be extended to reference dosimetry in Ir-192 clinical brachytherapy.

Abstract

Aim

To determine the energy and dose dependence of GafChromic EBT3-V3 film over an energy range 0.2 mm Al HVL to 6 MV.

Background

The decay scheme of a brachytherapy source may be complex and the spectrum of energy can be wide. LiF TLDs are the golden standard recommended for dosimetric measures in brachytherapy, for their energy independence, but TLDs could be not available in some centres. An alternative way to perform dose measurements is to use GafChromic films, but they show energy dependence.

Methods and materials

Films have been irradiated at increasing dose with three different beams: 6 MV beam, TPR20, 10 = (0.684 ± 0.01), HVL = (2.00 ± 0.01)mmAl and HVL = (0.20 ± 0.01)mmAl. Calibration curves were generated using the same dose range (0cGy to 850cGy) for the three energies. Using the 6 MV calibration curve as reference, the film response in terms of net optical density (OD) was evaluated.

Results

The difference in the calibration curve obtained by irradiating the film with 6 MV and 2 mm Al HVL energy beams is less than 3 %, within the calibration uncertainty, in the dose range 500-850cGy. The OD of EBT3-V3 film is significantly lower at 0.2 mmAl HVL compared to 6 MV, showing differences up to 25 %.

Conclusion

Within the range 6 MV-2 mm Al HVL and dose higher than 500cGy, GafChromic EBT3-V3 films are energy independent. In this dose range, films can be calibrated in a simple geometry, using a 6 MV Linac beam, and can be used for brachytherapy sources dose measures. The use of EBT3 films can be extended to reference dosimetry in Ir-192 clinical brachytherapy.

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Keywords

GafChromic EBT3-V3; Dosimetry; Energy dependence; Dose dependence; IPEM standard; DIN6809-4 standard

About this article
Title

Energy and dose dependence of GafChromic EBT3-V3 film across a wide energy range

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 25, No 1 (2020)

Pages

60-63

Published online

2020-01-01

DOI

10.1016/j.rpor.2019.12.007

Bibliographic record

Rep Pract Oncol Radiother 2020;25(1):60-63.

Keywords

GafChromic EBT3-V3
Dosimetry
Energy dependence
Dose dependence
IPEM standard
DIN6809-4 standard

Authors

Sarah Bassi
Donal Cummins
Patrick McCavana

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