title: Energy response of EBT3 radiochromic films: implications for dosimetry in kilovoltage range.
abstract: 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 60Co 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 60Co 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 60Co was determined for each EBT3 film. The netOD of the red color showed reproducible response (within 1%) for both batches when irradiated using the 60Co source. For a given dose of 1 Gy of kVp X-ray, the response relative to 60Co using the three color channels (red, green, and blue) decreases with decrease in kVp, reaching a maximum underresponse of ~ 20% for the 70 kVp. A significant underresponse of ~ 5% was observed at 300kVp. Responses of MV X-ray beams with respect to 60Co 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.
authors.affiliation: University of Calgary. edviba@gmail.com.
authors.forename: J Eduardo
authors.initials: JE
authors.lastname: Villarreal-Barajas
authors.forename: Rao F H
authors.initials: RF
authors.lastname: Khan
mesh_terms: D002138:Calibration; D003037:Cobalt Radioisotopes; D004307:Dose-Response Relationship, Radiation; D005373:Film Dosimetry / Q000295:instrumentation*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D019047:Phantoms, Imaging; D012867:Skin / Q000528:radiation effects*; D014867:Water / Q000737:chemistry; D014965:X-Rays
chemical_list: D003037:Cobalt Radioisotopes; D014867:Water