EBT3 and EDR2 film dosimetry for scanning carbon ion beams / 中华放射医学与防护杂志

ABSTRACT

Objective To investigate EBT3 and EDR2 film responses to different linear energy transfers ( LETs) and doses from carbon ion beams. Methods EBT3 and EDR2 films were calibrated by two methods. In the first method, films were placed at the same depth within a phantom and irradiated by beams with different parameters such as beam energy. In the second method, films were separately placed at different depths in a phantom and irradiated by the same beams. These methods were used to irradiate films with ions of different LETs. Results For EBT3 film, the dose calibration curves correlated with different LETs appeared to be typical hyperbolic curves with a maximum difference between the curves of ± 17％ (1σ). Meanwhile, the shape of the dose calibration curves for EDR2 film appeared to be linear. The values along all these curves were within ± 27.4％ (1σ) of the value for the average curve. The dose responses of both films were inversely proportional to LETs. The sensitivity of EBT3 film was inversely proportional to the dose, while the sensitivity of EDR2 film showed no relationship with the dose. Conclusions Influenced by the dual factor of LET and dose, the application of EBT3 film was limited in carbon ion. However, without no dose dependence, EDR2 film could be used to measure dose distributions created by single LET carbon ion beam.