Development of a radiochromic film dosimetry readout system.

Radiochromic film is widely recognized for its high spatial resolution and ease of use in radiation dosimetry, but accurate and artifact-free readout remains a challenge. In this work, we evaluate and compare three different radiochromic film imaging systems: a conventional flatbed scanner, a diffuse light field and camera setup, and a custom-built scanning point source and detector system. We investigate each system's optical characteristics, imaging performance, and clinical utility, with a particular focus on small field dosimetry, where conventional systems often fall short. Our results highlight significant limitations in the diffuse light field system due to stray light contamination which leads to dose underestimation in small irradiated fields. The point source system demonstrated excellent accuracy and robustness across all field sizes with no measurable stray light or polarization effects. This work demonstrates that a purpose-built point source scanning system offers a reliable alternative to commercial flatbed scanners.