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SU‐E‐T‐224: An Assessment of EBT2 Gafchromic Film as a Potential Means for Depth Dose Measurement of Radiotherapy Beams
Author(s) -
Arjomandy B,
Tailor R,
Zhao L,
Devic S
Publication year - 2011
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3612174
Subject(s) - materials science , beam (structure) , dosimetry , optics , ionization chamber , dose profile , nuclear medicine , physics , ion , medicine , quantum mechanics , ionization
Purpose: The Gafchromic EBT2 film was investigated as a potential mean for depth dose (DD) measurement of broad range of radio‐therapy beam‐modalities and energies. Methods: Gafchromic EBT2 films were exposed to 6 Gy dose from various beams in water for DD measurements. The beams employed for this study comprised of KV x‐rays (75 kVp), 60Co, Mega‐voltage x‐rays (6 &18MV), electrons (7 & 20 MeV), and spot‐scanning proton beams (180 & 150 MeV). Film optical densities (OD) were measured using a flat bed scanner. For each beam, film response measured over the dose range 0.6–6.2 Gy, was employed for OD‐to—dose conversion. Results: for all mega‐voltage photon & electron beams, percentage depth‐doses measured with EBT2 showed an excellent agreement (<1.5%) with those measured with ion chambers. In case of 75 kVp (nominal), a small over‐response is observed at deep depths (d > 2 cm) due to beam hardening. In contrast, an under‐response in the Bragg‐peak region is observed for proton beams due to quenching effects similar to the results published for EBT1. However, the suggested empirical corrections enable good agreement with ion‐chamber data for these beams as well. Conclusion: The results indicate that EBT2 is able to serve as a reliable tool for measuring DDs for all radiotherapy beams in general with a high spatial resolution and reproducibility.