High dose-per-pulse electron beam dosimetry : Usability and dose-rate independence of EBT3 Gafchromic films: Usability
(2017) In Medical Physics 44(2). p.725-735- Abstract
Purpose: The aim of this study was to assess the suitability of Gafchromic EBT3 films for reference dose measurements in the beam of a prototype high dose-per-pulse linear accelerator (linac), capable of delivering electron beams with a mean dose-rate (Dm) ranging from 0.07 to 3000 Gy/s and a dose-rate in pulse (Dp) of up to 8 × 106 Gy/s. To do this, we evaluated the overall uncertainties in EBT3 film dosimetry as well as the energy and dose-rate dependence of their response. Material and methods: Our dosimetric system was composed of EBT3 Gafchromic films in combination with a flatbed scanner and was calibrated against an ionization chamber traceable to primary standard. All sources of uncertainties in... (More)
Purpose: The aim of this study was to assess the suitability of Gafchromic EBT3 films for reference dose measurements in the beam of a prototype high dose-per-pulse linear accelerator (linac), capable of delivering electron beams with a mean dose-rate (Dm) ranging from 0.07 to 3000 Gy/s and a dose-rate in pulse (Dp) of up to 8 × 106 Gy/s. To do this, we evaluated the overall uncertainties in EBT3 film dosimetry as well as the energy and dose-rate dependence of their response. Material and methods: Our dosimetric system was composed of EBT3 Gafchromic films in combination with a flatbed scanner and was calibrated against an ionization chamber traceable to primary standard. All sources of uncertainties in EBT3 dosimetry were carefully analyzed using irradiations at a clinical radiotherapy linac. Energy dependence was investigated with the same machine by acquiring and comparing calibration curves for three different beam energies (4, 8 and 12 MeV), for doses between 0.25 and 30 Gy. Dm dependence was studied at the clinical linac by changing the pulse repetition frequency (f) of the beam in order to vary Dm between 0.55 and 4.40 Gy/min, while Dp dependence was probed at the prototype machine for Dp ranging from 7 × 103 to 8 × 106 Gy/s. Dp dependence was first determined by studying the correlation between the dose measured by films and the charge of electrons measured at the exit of the machine by an induction torus. Furthermore, we compared doses from the films to independently calibrated thermo-luminescent dosimeters (TLD) that have been reported as being dose-rate independent up to such high dose-rates. Results: We report that uncertainty below 4% (k = 2) can be achieved in the dose range between 3 and 17 Gy. Results also demonstrated that EBT3 films did not display any detectable energy dependence for electron beam energies between 4 and 12 MeV. No Dm dependence was found either. In addition, we obtained excellent consistency between films and TLDs over the entire Dp range attainable at the prototype linac confirming the absence of any dose-rate dependence within the investigated range (7 × 103 to 8 × 106 Gy/s). This aspect was further corroborated by the linear relationship between the dose-per-pulse (Dp) measured by films and the charge per pulse (Cp) measured at the prototype linac exit. Conclusion: Our study shows that the use of EBT3 Gafchromic films can be extended to reference dosimetry in pulsed electron beams with a very high dose rate. The measurement results are associated with an overall uncertainty below 4% (k = 2) and are dose-rate and energy independent.
(Less)
- author
- Jaccard, Maud ; Petersson, Kristoffer LU ; Buchillier, Thierry ; Germond, Jean François ; Durán, Maria Teresa ; Vozenin, Marie Catherine ; Bourhis, Jean ; Bochud, François O. and Bailat, Claude
- publishing date
- 2017
- type
- Contribution to journal
- publication status
- published
- keywords
- dose-rate dependence, EBT3 Gafchromic films, energy dependence, high dose-per-pulse, high dose-rate
- in
- Medical Physics
- volume
- 44
- issue
- 2
- pages
- 725 - 735
- publisher
- American Association of Physicists in Medicine
- external identifiers
-
- scopus:85015606155
- pmid:28019660
- ISSN
- 0094-2405
- DOI
- 10.1002/mp.12066
- language
- English
- LU publication?
- no
- additional info
- Publisher Copyright: © 2016 American Association of Physicists in Medicine.
- id
- 3b1187c1-1b0d-4fbe-a27a-1de6fb762ace
- date added to LUP
- 2021-11-03 18:13:57
- date last changed
- 2024-06-16 22:40:31
@article{3b1187c1-1b0d-4fbe-a27a-1de6fb762ace,
abstract = {{<p>Purpose: The aim of this study was to assess the suitability of Gafchromic EBT3 films for reference dose measurements in the beam of a prototype high dose-per-pulse linear accelerator (linac), capable of delivering electron beams with a mean dose-rate (D<sub>m</sub>) ranging from 0.07 to 3000 Gy/s and a dose-rate in pulse (D<sub>p</sub>) of up to 8 × 10<sup>6</sup> Gy/s. To do this, we evaluated the overall uncertainties in EBT3 film dosimetry as well as the energy and dose-rate dependence of their response. Material and methods: Our dosimetric system was composed of EBT3 Gafchromic films in combination with a flatbed scanner and was calibrated against an ionization chamber traceable to primary standard. All sources of uncertainties in EBT3 dosimetry were carefully analyzed using irradiations at a clinical radiotherapy linac. Energy dependence was investigated with the same machine by acquiring and comparing calibration curves for three different beam energies (4, 8 and 12 MeV), for doses between 0.25 and 30 Gy. D<sub>m</sub> dependence was studied at the clinical linac by changing the pulse repetition frequency (f) of the beam in order to vary D<sub>m</sub> between 0.55 and 4.40 Gy/min, while D<sub>p</sub> dependence was probed at the prototype machine for D<sub>p</sub> ranging from 7 × 10<sup>3</sup> to 8 × 10<sup>6</sup> Gy/s. D<sub>p</sub> dependence was first determined by studying the correlation between the dose measured by films and the charge of electrons measured at the exit of the machine by an induction torus. Furthermore, we compared doses from the films to independently calibrated thermo-luminescent dosimeters (TLD) that have been reported as being dose-rate independent up to such high dose-rates. Results: We report that uncertainty below 4% (k = 2) can be achieved in the dose range between 3 and 17 Gy. Results also demonstrated that EBT3 films did not display any detectable energy dependence for electron beam energies between 4 and 12 MeV. No D<sub>m</sub> dependence was found either. In addition, we obtained excellent consistency between films and TLDs over the entire D<sub>p</sub> range attainable at the prototype linac confirming the absence of any dose-rate dependence within the investigated range (7 × 10<sup>3</sup> to 8 × 10<sup>6</sup> Gy/s). This aspect was further corroborated by the linear relationship between the dose-per-pulse (D<sub>p</sub>) measured by films and the charge per pulse (C<sub>p</sub>) measured at the prototype linac exit. Conclusion: Our study shows that the use of EBT3 Gafchromic films can be extended to reference dosimetry in pulsed electron beams with a very high dose rate. The measurement results are associated with an overall uncertainty below 4% (k = 2) and are dose-rate and energy independent.</p>}},
author = {{Jaccard, Maud and Petersson, Kristoffer and Buchillier, Thierry and Germond, Jean François and Durán, Maria Teresa and Vozenin, Marie Catherine and Bourhis, Jean and Bochud, François O. and Bailat, Claude}},
issn = {{0094-2405}},
keywords = {{dose-rate dependence; EBT3 Gafchromic films; energy dependence; high dose-per-pulse; high dose-rate}},
language = {{eng}},
number = {{2}},
pages = {{725--735}},
publisher = {{American Association of Physicists in Medicine}},
series = {{Medical Physics}},
title = {{High dose-per-pulse electron beam dosimetry : Usability and dose-rate independence of EBT3 Gafchromic films: Usability}},
url = {{http://dx.doi.org/10.1002/mp.12066}},
doi = {{10.1002/mp.12066}},
volume = {{44}},
year = {{2017}},
}