Measurements of Radiochromic Films (EBT3 and EBT-XD) Using Three Portable Colorimeters

The authors recently proposed a method for on-site dosimetry by a combination of radiochromic film and portable colorimeter. To test and expand the applicability of this method, dosimetric properties of radiochromic reactions were examined for six combinations of two popular Gafchromic films (EBT3 and EBT-XD) and three commercially-available portable colorimeters (nix pro2, nix spectro2 and Spectro1 Pro; abbreviated to “NixP”, “NixS” and “SpoP”, respectively). EBT3 and EBT-XD were irradiated with 160 kV X-rays at 0.3 to 40Gy and 1 to 80 Gy, respectively, and the radiation-induced color levels of RGB and CMMK components were measured with the three colorimeters. Angle dependence was examined by reading at 15° intervals. As results, it was judged that all combinations would work effectively as tools for on-site dosimetry. NixP and NixS showed advantages that they were applicable to a wider dose range for both films, while Spo1 worked better in a lower dose range. On the other hand, Spo1 had an advantageous feature of no angular dependence in reading films, while NixP and NixS showed significant angle-dependent changes. These differences were presumed to attribute to the different geometries of LED light emission; it came from all directions (ring-shape source) in Spo1, 4 directions in NixP, and 8 directions in NixS. These findings would expand the applicability of the proposed on-site dosimetry method to various occasions.