Proton therapy uses proton beams with energies typically between 50 and 230
MeV to treat cancerous tumors very efficiently, while protecting as much as
possible surrounding healthy tissues from radiation damage. Protons
interacting with matter inevitably induce secondary radiation from which all
people inside the proton therapy center have to be protected. The ambient dose equivalent H*(10) in such a facility is mainly due to neutrons, which can have energies up to 230 MeV. Although various dose monitoring systems
sensitive to high energy neutrons have already been developed, the response
function of these detectors is often insufficiently characterized, and so are
the calibration factors appropriate for the specific neutron spectra
encountered inside a proton therapy facility. In this work, the Monte Carlo
code MCNPX 2.5.0 has been used to study the response function of the
extended-range rem-meter WENDI-2 from thermal energies up to 5 GeV. A good
match has been obtained with equivalent simulation results found in
literature. As a first step towards the characterization of the WENDI-2
response in continuous neutron fields, MCNPX simulations have also been
carried out for the case-study of a bunker around an 18 MeV H-cyclotron,
which involves neutron fields from thermal energies up to 18 MeV.
MCNPX simulations of the response of the extended-range rem meter WENDI-2