A BEAM SHAPING ASSEMBLY FOR NEUTRON CAPTURE THERAPY

In order to improve flux and quality of the neutron source, an aspect of the present disclosure provides a beam shaping assembly for neutron capture therapy comprising: a beam inlet; a target, wherein the target has nuclear reaction with an incident proton beam from the beam inlet to produce neutrons, and wherein the neutrons form a neutron beam defining a main axis; a moderator adjoining to the target, wherein the neutrons are moderated by the moderator to epithermal neutron energies, and wherein an outer surface of the moderator includes at least a first tapered section; a reflector surrounding the moderator, wherein the reflector leads the neutrons deviated from the main axis back to enhance epithermal neutron beam intensity; a thermal neutron absorber adjoining to the moderator, wherein the thermal neutron absorber is used for absorbing thermal neutrons so as to avoid overdosing in superficial normal tissue during therapy; a radiation shield arranged inside the beam shaping assembly, and wherein the radiation shield is used for shielding leaking neutrons and photons so as to reduce dose of the normal tissue not exposed to irradiation; and a beam outlet.