The objective of this study is to evaluate the suitability of recently introduced radiochromic film EBT3 for clinical dosimetry in the kilovoltage (kV) range. For this purpose, a kV X‐ray irradiator, X RAD 320ix in the range 70 to 300 kVp, a clinical source, a 6 MV and an 18 MV X‐ray clinical beam from a Varian linear accelerator were calibrated following AAPM dosimetry protocols. EBT3 films from two different EBT3 batches were placed side‐by‐side on the surface of a water phantom; doses from 0.5 to 4 Gy were delivered. Similarly, irradiations were performed for and 6 and 18 MV beams in a water‐equivalent phantom. Films were reproducibly placed at the center of a flatbed scanner and 48‐bit RGB scans were obtained both pre‐ and postirradiations. Net optical density (netOD) and response for a given radiation quality relative to was determined for each EBT3 film. The netOD of the red color showed reproducible response (within 1%) for both batches when irradiated using the source. For a given dose of 1 Gy of kVp X‐ray, the response relative to using the three color channels (red, green, and blue) decreases with decrease in kVp, reaching a maximum underresponse of for the 70 kVp. A significant underresponse of was observed at 300 kVp. Responses of MV X‐ray beams with respect to at the 1 Gy dose level showed no statistically significant difference. A relatively small difference in the response was observed between the two EBT3 batches used in this study in the kV X‐ray range.
PACS numbers: 87.56.B, 87.57.uq