Harmonization of proton treatment planning for head and neck cancer using pencil beam scanning: first report of the IPACS collaboration group.

A collaborative network between proton therapy (PT) centres in Trento in Italy, Poland, Austria, Czech Republic and Sweden (IPACS) was founded to implement trials and harmonize PT. This is the first report of IPACS with the aim to show the level of harmonization that can be achieved for proton therapy planning of head and neck (sino-nasal) cancer. CT-data sets of five patients were included.