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Evaluation of GafChromic EBT prototype B for external beam dose verification
M Todorovic1, M Fischer, F Cremers
1Department of Radiotherapy and Radio-Oncology, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany. todorovic@uke.uni-hamburg.de
Medical Physics
|June 7, 2006
Summary
The new GafChromic EBT prototype B film offers a ten-fold increase in sensitivity for external beam dose verification compared to previous GafChromic films. This advancement, combined with a flat-bed scanner and MatLab analysis, enables accurate verification of radiation therapy doses.
Area of Science:
- Medical Physics
- Radiation Oncology
- Radiological Imaging
Background:
- Accurate dose verification is critical in external beam radiation therapy.
- GafChromic films are widely used for dosimetry, but sensitivity and stability can be limiting factors.
Purpose of the Study:
- To investigate the performance of the new GafChromic EBT prototype B film for external beam dose verification.
- To compare its characteristics with existing dosimetry films and methods.
Main Methods:
- Characterization of GafChromic EBT prototype B film properties (dose response, post-irradiation coloration, field size influence) using a flat-bed scanner.
- Quantitative analysis of two-dimensional dose distributions using a custom MatLab program.
- Verification of Stereotactic Radiotherapy (SRT) and Intensity-Modulated Radiation Therapy (IMRT) plans.
Main Results:
- GafChromic EBT prototype B exhibits ten times higher sensitivity than GafChromic HS and three times higher response than Kodak EDR2 film in the 0.1–8 Gy range.
- The film shows minimal temporal optical density growth and no dependence on calibration field size.
- Verification using the EBT prototype B and MatLab analysis revealed minimal discrepancies between planned and delivered doses in SRT and IMRT.
Conclusions:
- GafChromic EBT prototype B film is a highly sensitive and stable dosimeter for external beam dose verification.
- The combination of GafChromic EBT prototype B, a flat-bed scanner, and MatLab software provides a robust and advantageous method for radiation therapy verification.