A depth of interaction detector with uniform pulse-height comprises a
multi-layer scintillator obtained by coupling at least two scintillator
cells on a plane and then stacking the planar coupled scintillator cells,
in layers, up to at least two stages and a light-receiving element
connected to the bottom face of each scintillator cell of this
multi-layer scintillator, wherein the detector is provided with a means
for discriminating the position of a scintillator cell, which receives
radiant rays and emits light rays and a means for making, uniform, the
quantity of the light emitted from each scintillator cell and received by
the light-receiving element. The detector can provide precise detection
information even when radiation is absorbed by and emitted from a
scintillator layer positioned above the scintillator layer optically
coupled to the light-receiving element, permits the production of a depth
of interaction detector having a three-dimensional depth of
interaction-detecting function and can provide the same total output
signal, which is independent of the position or a specific scintillator
cell practically emitting light if the radiation energy is identical.