In the last decades, cancer treatment modalities have been moved towards high technological developments that indicate in the external beam radiotherapy the primacy of delivering a highly conformal radiation dose to the target volume. In this scenario, proton therapy at Paul Scherrer Institute (PSI) occupies a relevant role because it represents the first clinic capable of applying proton radiotherapy with Spot-Scanning technique by means of dedicated beam delivery system mounted over a Gantry, worldwide. In this field, a study focused on determining how novel materials behave when traversed by protons has been carried out. The plastic candidates would be an extremely useful advancement in dosimetry for high energy proton beams, due to the lack of experimental or theoretical investigations on this aspect.The advantages of using plastic materials instead of water are better positioning accuracy, less time-consuming work flow in pre-treatment stages of the quality assurance and easier managing with respect to the reference material (water).