Abstract
In BNCT for head and neck tumors delivered with a horizontal beam, the presence of missing tissue near the beam path can cause reduction in neutron fluence rate in adjacent tissue regions due to the loss of scattered neutrons. These regions are referred to as neutron depleted areas. By placing a tissue equivalent compensator in these missing tissue regions, the lateral scatter equilibrium is partially restored, increasing the local neutron fluence rate and, consequently, the dose to the target volume while maintaining normal tissue exposure within tolerance limits.