title: Reply to the comments on "comparative study with new accuracy metrics for target volume contouring in PET image guided radiation therapy".
abstract: This communication is submitted in response to the letter of van den Hoff and Hofheinz (2013). Based on findings in their earlier study (Hofheinz , 2010) the letter criticizes the use of a physical positron emission tomography (PET) phantom with "cold wall" volumes of interest, in part of the evaluation of PET segmentation tools in our experiment reported in this issue (Shepherd , 2012). In addition, the letter raises concerns about the low number of independent expert (manual) delineations used in Shepherd , (2012) to assess accuracy of tumor segmentation in patient images, and disambiguates the details of one of the segmentation methods involved in Shepherd , (2012).
authors.forename: Tony
authors.initials: T
authors.lastname: Shepherd
mesh_terms: D006801:Humans; D049268:Positron-Emission Tomography; D061089:Radiotherapy, Image-Guided