Reaction of three UV exposure to gafchromic EBT-2 and EBT-3

Gafchromic films (GAFs) are used for the Xray dose measurement in the diagnostic examination. It is begun to use for the three-dimensional X-rays dose measurement using the high-resolution characteristic in computed tomography. However, it is necessary to solve a problem of unevenness of active layer of GAFs. It is suggested that the ultraviolet (UV) is substitute as an X-ray. However, wavelength of appropriate UV are unidentified. This study is to decide a wavelength of the UV. Peak wavelength of 245 nm, 310 nm and 365 nm UV were irradiate to the EBT2 and EBT3. The UV rays were irradiated for 5, 15, 30 and 60 minutes, and irradiation was repeated afterwards until 360 minutes every 60 minutes. The images were split in RGB, and R images were used. ROI of the diameter 1/2 inch was set in the center of subtracted GAF images, and the graph of UV irradiation time and the mean pixel value were made. There was a reaction in front and back of GAF EBT3 and back of EBT2 in UV-A and B. However, UV-C had few reactions with both aspects of GAF EBT2 and EBT3. It should be used UV-A for a fact because a wavelength of UV-B may affect the human body.