Design and implementation of a Python-based tool for advanced GafChromic EBT3 dosimetric analysis in a challenging radiotherapy setup

Radiochromic film dosimetry represents a valuable method for verifying dose distributions in radiotherapy, offering high spatial resolution and ease of use. However, its implementation faces challenges beyond standard protocols, particularly in specialized applications requiring measurements at high dose ranges. This thesis addresses these limitations through the development, validation, and application of a Python-based open-source library for radiochromic film dosimetry, with specific focus on measuring radiation dose distributions in dental tissues using high dose ranges in non-standard experimental setups. The methodology encompasses three primary components: development of a flexible Python library for calibrating and fitting radiochromic film response curves using multichannel approach, validation of calibration curve fits using non-standard experimental setups with simulated teeth in a 24-well cell plate configuration, and practical application of calibrated Gafchromic film to measure absorbed dose in complex heterogeneous media, specifically human extracted teeth exposed to 22 Gy radiation. Extensive validation through gamma analysis demonstrated that the multichannel approach, particularly the weighted sum technique integrating data from all three color channels, offers superior performance compared to commercial single-channel alternatives. The multichannel method consistently produced better gamma passing rates across all dose ranges, not just at doses above 10 Gy where single-channel approaches typically underperform. The open-source nature of the developed library offers significant advantages for clinical implementation, requiring minimal Python knowledge and no financial investment. Future work should include comparison with Monte Carlo simulations to overcome limitations of treatment planning systems in heterogeneous media, expansion of the library with additional fitting functions and gamma analysis capabilities.