Beam shaping assembly for neutron capture therapy

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, the neutrons form a neutron beam, and the neutron beam defines an axis;
• a moderator adjoining to the target, wherein the neutrons are moderated by the moderator to epithermal neutron energies, the moderator comprises a main body and a supplement section surrounding the main body, the materials of the main body and the supplement section are different, the main body is prepared from at least one of D2O, AlF3, CaF2, Li2CO3, MgF2 and Al2O3, and the supplement section is prepared from any one of Zn, Mg, Al, Ti, La, Pb, Zr and Bi;
• a reflector surrounding the moderator, wherein the reflector leads deflected neutrons 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, 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.

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, the neutrons form a neutron beam, and the neutron beam defines an axis;
• a moderator adjoining to the target, wherein the neutrons are moderated by the moderator to epithermal neutron energies, the moderator comprises a main body and a supplement section, the main body comprises a first tapered section adjoining to the target and a cylindrical section adjoining to the first tapered section , the supplement section surrounds the main body, the supplement section includes a first end, a second end, and an inner wall extending from the first end to the second end;
• the cylindrical section includes a third end connecting with the first tapered section, an fourth end and an outer wall extending from the third end to the fourth end, the inner wall connects with the outer wall, the first end connects with the third end, the second end connects with the fourth end and the supplement section is arranged farther from the target than the main body;
• a reflector surrounding the moderator, wherein the reflector leads deflected neutrons 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, 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.