The medical use of proton beams for precise treatments of complex tumours has become more widespread over the last few years. It offers significant advantages over radiotherapy based on electron and photon beams.
Nevertheless, the interaction of the energetic protons with the high-Z material along the beam line and with the patient leads to the production of secondary neutrons. This unavoidable side effect represents a serious issue for radiological protection since it is the major contributor to the patient’s peripheral, or whole-body, unwanted dose and could lead to secondary cancer later in life.
Moreover these secondary neutrons constitute the main radiation hazard for the workers in the laboratory and for members of the public. It is therefore essential to characterise the neutron field produced in proton therapy facilities in order to minimise the risks associated with the unwanted dose exposure, and to design and develop efficient shielding.