Illustration of the OAR skin and the position of the in vivo Gafchromic dosimetry films using the image of a 7 F-IMRT plan in the isocenter plane. The OAR skin was defined as a 3 mm strip from the surface of the skin to the PTV. PTV for the IMRT plans included the same PTV used for the 3D-CRT plans plus an extension into the air anteriorly of the skin of 1.5 cm to ensure appropriate opening of the 160 MLC Multileaf Collimator. The numbers denote the position of the in vivo Gafchromic dosimetry films (1 = lateral position, 2 = central position, 3 = medial position).