A protocol for EBT3 radiochromic film dosimetry using reflection scanning

Area of Science:

• Medical Physics
• Radiation Dosimetry
• Image Analysis

Background:

• Radiochromic film dosimetry is crucial for accurate radiation dose measurement.
• Gafchromic EBT3 film is widely used, but optimizing its performance is essential.
• Reflection scanning offers potential advantages over traditional transmission scanning.

Purpose of the Study:

• To evaluate the performance of Gafchromic EBT3 film dosimetry using reflection measurements.
• To develop a precise and accurate calibration protocol for reflection film dosimetry.
• To compare reflection and transmission scanning modes for EBT3 film.

Main Methods:

• Irradiated EBT3 film pieces to doses from 0 to 8 Gy.
• Scanned films using both reflection and transmission modes at various resolutions.
• Analyzed red and green color channels for film response, sensitivity, uncertainty, and accuracy.
• Evaluated resolution using a microscope target and optimized calibration ranges.

Main Results:

• Reflection scanning with the red channel showed higher sensitivity than transmission, especially at low doses (<2 Gy).
• No resolution loss was observed in reflection mode.
• Higher uncertainties and reduced accuracy occurred in red channel reflection mode at doses >2 Gy due to saturation.
• Green channel reflection mode provided comparable results to red transmission mode for higher doses.

Conclusions:

• A two-color reflection scanning protocol is proposed for EBT3 film dosimetry.
• Utilize the red channel for doses <2 Gy and the green channel for doses >2 Gy.
• This protocol significantly improves precision and accuracy, particularly in the low-dose region.