Investigating the Spatial Resolution and Contrast of Peeled-Off Gafchromic EBT2 Film Exposed to 5 MeV Alpha Particles Analyzed via Color Channels

Abstract

The relationship between spatial resolution and contrast of peeled-off EBT2 Radiochromic film irradiated with monoenergetic alpha particles across various color channels has been investigated. Gafchromic EBT2 films, after removing their protective layer, were checked for homogeneity, and then they were exposed to 5 MeV alpha particles from 241Am source with various doses. A razor blade was used to create two distinct edges. The relation between the pixel values and contrast for different doses was studied. The edge spread function (ESF) data was fitted using the error function and then differentiated to derive the line spread function (LSF). All the channels except the blue one consistently exhibit a step transition between exposed and unexposed regions. In contrast, the blue channel displayed an irregular response, where the exposed area appeared unexpectedly brighter than the unexposed area, indicating limited sensitivity to alpha particle exposure. The average spatial resolution, expressed as the full width at half maximum (FWHM), was calculated to be (31 ± 6.7) µm, (25.6 ± 3.4) µm, (26.7 ± 3.1) µm, and (23.8 ± 3.3) µm for the red and green channels, as well as the weighted and unweighted gray images, respectively, indicating that the unweighted gray image and the green channel provide the highest spatial resolution.