A radiation detector having a plurality of pixels is provided. A respective one of the plurality of pixels includes a base substrate; a thin film transistor on the base substrate; an insulating layer on a side of the thin film transistor away from the base substrate; a photosensor on a side of the insulating layer away from the base substrate; a passivation layer on a side of the photosensor away from the base substrate; a scintillation layer on a side of the passivation layer away from the base substrate; and a reflective layer on a side of the scintillation layer away from the base substrate. The photosensor includes a first polarity layer in direct contact with the passivation layer. All sides of the first polarity layer other than a side internal to the photosensor are entirely in direct contact with the passivation layer.