Can cell phones be used as radiation detectors?

Obviously, in order to take photographs, a cell phone has to be sensitive to light, photons, or gamma rays. However, I've read in a number of scientific articles that cell phones are also sensitive to beta rays -- electrons and positrons -- and to alpha rays -- neutrons and protons. Why is this the case, exactly? Can cell phones distinguish between the different kinds of radiation? Can cell phones determine when radiation has reached dangerous levels.