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The repeatability of the scanner EPSON 10000 XL in radiochromic film dosimetry was studied. Several patterns were observed and analyzed. The dispersion of the measures of the scanner as a function of the pixel position was calculated for resolutions 50, 72, 96 and 150 dpi. The distance between the position of the same pixel in different scanners, as well as the dependency of this distance with the position in the axis perpendicular to the scanner lamp, was examined. Inter-scan and intra-scan variability of the scanner response was studied. The scanner noise is not independent of the pixel position; its variance follows periodical patterns in both axes, which causes grid patterns. The initial positioning and the speed of the scanner lamp varies between scans. Consequently, average pixel values from different scans have more uncertainty at the end of the scanning reading than at the beginning. The scanner response varies not only inter-scan, but also intra-scan. This is caused by deviations of the individual CCD detectors from their reference state. Three new perturbations which affect radiochromic film dosimetry with flatbed scanners were discovered and analyzed: grid patterns, scanning reading repeatability and intra-scan variations. A novel correction method which reduces inter- and intra-scan variations was proposed. [ABSTRACT FROM AUTHOR]