The Monte Carlo transport codes LAHET and MCNP were used to calculate
energy fluence spectra at three neutron therapy facilities. The result
s compare very favourably with measured data. Kerma spectra and the ra
tio of ICRU muscle tissue kerma to A-150 kerma, along with the carbon
to oxygen kerma ratio, were determined. Absorbed dose rate calculation
s are in reasonable agreement with measured values. Use of these codes
to study modifications to existing therapy beams is briefly discussed
.