Ionising radiation can be observed and quantified by specific instruments, but not by sense organs of humans. The most commonly used methods for radiation monitoring and detection are outlined in brief in the following, -dosimeters are used for monitoring the total radiation dose of a person in a certain working period. The radiation measurement is based on specially prepared films that accumulate the radiation. -Radiation meters are used for on-line radiation measurements. The measurement technique is usually based on Geiger-Muller gas tubes. These tubes have certain minimum radiation window thickness that prevents low energy radiation detection. -Beta counters used in biological laboratories are based on light emitting liquid scintillators. The scintillation liquid is mixed with the radioactive labelled sample liquid. The generated light is collected and detected by photo multiplier tubes. -Gamma counters are usually based on scintillation crystals. The measured sample is put close to the crystal, which emits light when radiated by the gamma rays & the light is collected.