A method of detecting and/or analyzing a radioactive source emitting charged or neutral particles in a biological tissue, consisting essentially in using scintillating fibers having particular ratios of length or diameter to range of the particles emitted by the source scanning the surface of the material with the detection rod collecting by means of a SiPM, the scintillation light output generated by the particles having interacted with the scintillating fibers and emitted at the outlet end optionally selecting signals corresponding to the particles entering the scintillating fibers in a substantially axial direction, that eliminates the particles from certain angles between the axis of the scintillating fiber and the direction of the particles entering the scintillating fiber, correlating the scintillation light output and the selected signals to the presence of a source of radiation located in the material to be analyzed and optionally communicating these data to the user.
