A beam shaping assembly for neutron capture therapy includes a beam inlet, a target having nuclear reaction with an incident proton beam from the beam inlet to produce neutrons forming a neutron beam defining a main axis, a moderator adjoining to the target, a reflector surrounding the moderator, a thermal neutron absorber adjoining to the moderator, a radiation shield arranged inside the beam shaping assembly and a beam outlet. The neutrons are moderated to epithermal neutron energies. The target is received into the moderator. The reflector leads the neutrons deviated from the main axis back. The thermal neutron absorber is used for absorbing thermal neutrons so as to avoid overdosing in superficial normal tissue during therapy. The radiation shield is used for shielding leaking neutrons and photons so as to reduce dose of the normal tissue not exposed to irradiation.一種用於中子捕獲治療的射束整形體，包含：射束入口；靶材，其與自射束入口入射的質子束發生核反應以產生中子，該中子形成有一遷移主軸之中子射束；緩速體，其與靶材鄰接，該緩速體將自該靶材產生的中子減速至超熱中子能區，該靶材容納在該緩速體內；反射體，其包圍在緩速體外，該反射體將偏離主軸的中子導回，以提高超熱中子射束強度；熱中子吸收體，其與緩速體鄰接，該熱中子吸收體用於吸收熱中子，以減少治療時於淺層正常組織造成之劑量；輻射屏蔽，用於屏蔽滲漏的中子和光子；射束出口。
