Rapid calibration curve generation using single-sheet radiochromic film for proton-based stereotactic radiosurgery verification

Proton-based stereotactic radiosurgery (PSRS) holds promise for treating benign tumours, with patient-specific quality assurance (PSQA) playing a crucial role in ensuring high-quality clinical services. EBT3 films are a perfect tool for PSQA, particularly owing to their compatibility with small-field dosimetry. However, a successful absolute EBT3 dosimetry relies on detailed dose calibration, consuming much time and films. A novel approach has been developed in this study and tested to establish a calibration curve using a single sheet of EBT3 radiochromic films exposed to six multi-leaf collimator (MLC) fields. Notably, this method allows for the completion of a calibration curve in just 15 min, enabling the practical generation of new EBT3 calibrations daily. This single-sheet approach can generate a dose calibration curve with an error of less than 1.5% across the entire dose range and is well agreed to by traditional multi-film calibrations involving large fields, with a discrepancy of less than 0.8%.