Model selection for radiochromic film dosimetry

Area of Science:

• Medical Physics
• Radiation Dosimetry
• Image Analysis

Background:

• Radiochromic film dosimetry is crucial for accurate radiation dose measurement.
• Model selection is key to improving the precision of film dosimetry.
• Perturbation models require careful evaluation for optimal performance.

Purpose of the Study:

• To identify the most accurate model for radiochromic film dosimetry.
• To compare different channel-independent perturbation models.
• To assess the impact of pre-irradiation scanning and lateral corrections on dosimetry accuracy.

Main Methods:

• A model selection approach based on information theory was employed.
• Gamma-index analysis was used for validation on benchmark test cases.
• Multiple perturbation models were evaluated, including single-channel vs. multichannel and different perturbation types (Truncated Normal, Micke-Mayer).

Main Results:

• Scanning films before irradiation and applying lateral corrections significantly improved dosimetry accuracy.
• Increasing color channels did not consistently enhance accuracy for all perturbation models.
• The triple-channel model with Truncated Normal perturbations, using net optical density and lateral corrections, proved most accurate.

Conclusions:

• Pre-irradiation scanning and lateral corrections are vital for accurate radiochromic film dosimetry.
• The choice of perturbation model (Truncated Normal superior to Micke-Mayer) and channel number impacts accuracy.
• The optimized triple-channel model offers enhanced precision for radiotherapy dose verification.