Reducing non-uniformity error of radiochromic film in the diagnostic range by ultraviolet exposure: Preliminary study

Abstract

Thickness irregularity of active layer is made to express density irregularity. True data by the X-rays are extracted by exposing Ultraviolet (UV) rays that prohibited exposure are exposed for radiochromic film (RF). When UV is exposed, the density irregularity is corrected. In addition, RF is initialized, thereby improving of data acquisition. GAFCHROMIC EBT (GAF-EBT) film was exposed to UV light at 360 nm twice with a 2 hour interval. The distance from the UV tube to the GAF-EBT film was 165 cm. The GAF-EBT films were scanned after the first and second UV exposure, using a flat bed scanner. Analyses were performed by the density profile curve of the short and long axes of the GAFEBT. The density irregularity of the active layer of the film was corrected to 2.19 ± 0.49 (pixel value) by subtracting the density obtained with the first UV exposure from that with the second UV exposure of GAF-EBT on the short axis. On the long axis, the density irregularity of the active layer of GAFEBT was corrected to 2.67 ± 0.65 (pixel value). Uniform UV exposure data was identified. The measurement precision of the GAF-EBT film and its usefulness are improved by this method. © 2009 Springer-Verlag.