GAFChromic film dosimetry with a flatbed color scanner for Leksell Gamma Knife therapy

GAFChromic films MD-55-2 have recently been established widely in industrial, scientific, and medical applications as radiation dosimeters. We applied these films to the dosimetry for Leksell Gamma Knife therapy. We used a flatbed image scanner to take digital images of irradiated MD-55-2, and the data were converted to Red, Green and Blue pixel values. The absorbed dose, as derived from the response curve of the Red pixel value, was consistent with the Leksell Gamma Plan dose planning system, for exposures using collimator sizes, 4 mm, 8 mm, and 14 mm. However, the maximum dose in the exposure of the 18 rum collimator was measured to be about 5% smaller than Gamma Plan due to the density effect of the compound material in the head phantom. (C) 2004 American Association of Physicists in Medicine.