Abstract: A neutron capture therapy system includes a neutron ray generating unit, an irradiated body placing unit on which a patient (irradiated body) is placed, and a gamma ray detecting unit that detects gamma rays emitted from the patient (irradiated body). The gamma ray detecting unit includes an emission part that emits light or electrons as the gamma rays are incident thereon, an amplification part that amplifies and outputs the light or the electrons emitted from the emission part, a first neutron ray shielding part formed of a substance containing 6-lithium, and a second neutron ray shielding part formed of a light element. The first neutron ray shielding part is provided so as to cover at least a surface opposite to an adjacent surface adjacent to the amplification part, among surfaces of the emission part.

Abstract: A neutron capture therapy system includes a neutron ray generating unit, an irradiated body placing unit on which a patient (irradiated body) is placed, and a gamma ray detecting unit that detects gamma rays emitted from the patient (irradiated body). The gamma ray detecting unit includes an emission part that emits light or electrons as the gamma rays are incident thereon, an amplification part that amplifies and outputs the light or the electrons emitted from the emission part, a first neutron ray shielding part formed of a substance containing 6-lithium, and a second neutron ray shielding part formed of a light element. The first neutron ray shielding part is provided so as to cover at least a surface opposite to an adjacent surface adjacent to the amplification part, among surfaces of the emission part.

Abstract: By acquiring the neutron ray wave height distribution of the neutron rays and the gamma ray wave height distribution of only the gamma rays included in the radiant rays, how much gamma rays are detected as noise can be ascertained in a case where a certain determination threshold value Qth is set. That is, a relationship between the determination threshold value Qth and detection accuracy can be ascertained. Since the distributions are acquired on the basis of two measurements in a case where a filter that cuts the neutron rays N is used and in a case where the filter is not used, the relationship between the determination threshold value Qth and the detection accuracy can be accurately ascertained. Therefore, a determination threshold value adjusting unit can adjust a suitable determination threshold value Qth in conformity with demanded detection accuracy on the basis of the distributions.

Abstract: By acquiring the neutron ray wave height distribution of the neutron rays and the gamma ray wave height distribution of only the gamma rays included in the radiant rays, how much gamma rays are detected as noise can be ascertained in a case where a certain determination threshold value Qth is set. That is, a relationship between the determination threshold value Qth and detection accuracy can be ascertained. Since the distributions are acquired on the basis of two measurements in a case where a filter that cuts the neutron rays N is used and in a case where the filter is not used, the relationship between the determination threshold value Qth and the detection accuracy can be accurately ascertained. Therefore, a determination threshold value adjusting unit can adjust a suitable determination threshold value Qth in conformity with demanded detection accuracy on the basis of the distributions.