This collection contains 156 cases of MAASTRO Head and Neck images and RTStruct contours. Where PET exists, the frame of reference UID of the CT has been transferred to the PET. This collection may not be used for commercial purposes. This collection is freely available to browse, download, and use for scientific and educational purposes as outlined in the Attribution-NonCommercial 3.0 Unported (CC BY-NC 3.0) https://creativecommons.org/licenses/by-nc/3.0/. Please be sure to include the following citation if you make use of this data set : "Aerts, H. J. W. L., Velazquez, E. R., Leijenaar, R. T. H., Parmar, C., Grossmann, P., Carvalho, S., … Lambin, P. (2014, June 3). Decoding tumour phenotype by noninvasive imaging using a quantitative radiomics approach. Nature Communications. Nature Publishing Group. http://doi.org/10.1038/ncomms5006."