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Measurement of secondary neutron proton in therapy facilities

The need

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.

The impact

The measurement of secondary neutrons produced in proton therapy facilities is particularly challenging due to the pulsed structure of the beam and the wide energy range covered by the particles.

We work on the development and the characterisation of neutron spectrometers capable to cope with such issues, using a wide variety of techniques, based on both active and passive detectors. We are involved in international collaborations with European universities and laboratories focused on the measurement of out-of-field radiation around medical accelerators. We work in close contact with both public and private UK proton therapy centres.

The techniques and instruments we develop will also be suitable for use in other types of medical accelerators, such as Laser Driven Accelerators and Very High Energy Electron facilities.